Chronological correlations between the Pilbara and Kaapvaal cratons

Abstract

The early geological development of the Pilbara and Kaapvaal cratons has many features in common. Attempts have been made to correlate geologically similar features of the two cratons, and it has been postulated that they originated as contiguous components of a single continent, ‘Vaalbara’, during this time. The early geological histories of the Pilbara and Kaapvaal cratons are here compared in detail and the evidence that they were initially contiguous is assessed. These comparisons indicate significant differences in the chronologies of magmatic events within the granite–greenstone crusts of the Pilbara and Kaapvaal cratons. In addition, igneous correlatives emplaced during ca 2985 and 2782 Ma magmatic events on the Kaapvaal Craton have not been identified on the Pilbara Craton, and a well-defined 2760 Ma magmatic event, manifest as widespread emplacement of granitic rocks into the Pilbara granite–greenstone basement and eruption of flood basalts of the lower part of the Fortescue Group, is absent from the Kaapvaal Craton. Furthermore, similarities in first- and second-order transgression–regression cycles within the sedimentary supracrustal sequences may be attributable to global sea-level fluctuations, and thus may be irrevelant to the question of former contiguity. However, similarities in some aspects of the geological development of the Pilbara and Kaapvaal cratons imply that there were periods, extending for between 60 and 200 Ma, of the Archaean era during which the style of crust formation, intensity of volcanism and subaerial erosion, and magnitude of sea-level fluctuations may have varied on a global scale. Such similarities include the overall duration of formation of the granite–greenstone crusts from ca 3650 to 3100 Ma, the onset of craton-wide erosion in the interval ca 3125 to 3000 Ma, the major episodes of flood basaltic volcanism between 2760 and 2680 Ma, the predominance of chemical (carbonate and banded iron-formation) sedimentation between ca 2630 and 2440 Ma and the transition to widespread clastic sedimentation within the interval 2440 to 2200 Ma.

Full text

Precambrian Research 97 (1999) 165 –189
www.elsevier.com/locate/precamres
Chronological correlations between the Pilbara
and Kaapvaal cratons
D.R. Nelson a, b, *, A.F. Trendall b, W. Altermann c
aGeological Survey of Western Australia, Mineral House, 100 Plain Street, East Perth WA 6004, Australia
bWestern Australian Isotope Studies Research Group, Department of Applied Physics, Curtin University of Technology,
GPO Box U1987, Perth WA 6001, Australia
cInstitut fu
¨r Allgemeine und Angewandte Geologie, Luisenstrasse 37, Ludwig Maximilians Universita
¨tMu
¨nchen,
80333Mu
¨nchen, Germany
Accepted 21 April 1999
Abstract
The early geological development of the Pilbara and Kaapvaal cratons has many features in common. Attempts
have been made to correlate geologically similar features of the two cratons, and it has been postulated that they
originated as contiguous components of a single continent, ‘Vaalbara’, during this time. The early geological histories
of the Pilbara and Kaapvaal cratons are here compared in detail and the evidence that they were initially contiguous
is assessed. These comparisons indicate significant differences in the chronologies of magmatic events within the
granite–greenstone crusts of the Pilbara and Kaapvaal cratons. In addition, igneous correlatives emplaced during ca
2985 and 2782 Ma magmatic events on the Kaapvaal Craton have not been identified on the Pilbara Craton, and a
well-defined 2760 Ma magmatic event, manifest as widespread emplacement of granitic rocks into the Pilbara granite–
greenstone basement and eruption of flood basalts of the lower part of the Fortescue Group, is absent from the
Kaapvaal Craton. Furthermore, similarities in first- and second-order transgression–regression cycles within the
sedimentary supracrustal sequences may be attributable to global sea-level fluctuations, and thus may be irrevelant to
the question of former contiguity. However, similarities in some aspects of the geological development of the Pilbara
and Kaapvaal cratons imply that there were periods, extending for between 60 and 200 Ma, of the Archaean era
during which the style of crust formation, intensity of volcanism and subaerial erosion, and magnitude of sea-level
fluctuations may have varied on a global scale. Such similarities include the overall duration of formation of the
granite–greenstone crusts from ca 3650 to 3100 Ma, the onset of craton-wide erosion in the interval ca 3125 to
3000 Ma, the major episodes of flood basaltic volcanism between 2760 and 2680 Ma, the predominance of chemical
(carbonate and banded iron-formation) sedimentation between ca 2630 and 2440 Ma and the transition to widespread
clastic sedimentation within the interval 2440 to 2200 Ma. © 1999 Elsevier Science B.V. All rights reserved.
Keywords: Archaean; Craton; Granite–greenstone; Kaapvaal; Pilbara
* Corresponding author. Tel.: +61-89266-3736; fax: +61-89266-2377.
E-mail address: d.nelson@info.curtin.edu.au ( D.R. Nelson)
0301-9268/99/$ – see front matter © 1999 Elsevier Science B.V. All rights reserved.
PII: S0301-9268( 99) 00031-5

166 D.R. Nelson et al. /Precambrian Research 97 ( 1999) 165–189
1. Introduction comparable to these groups. Over much of its
outcrop area, the Ventersdorp Supergroup lies
unconformably upon the clastic sedimentarySome Archaean granite–greenstone cratons
exhibit remarkably similar lithological associa- sequences of the Witwatersrand Supergroup, which
in turn rests unconformably on the granite–green-tions, structural features and chronological histor-
ies. The best-known examples include the stone basement of the Kaapvaal Craton (Fig. 2).
The lithostratigraphy of the Ventersdorp succes-predominantly Late Archaean Yilgarn and
Superior cratons of Western Australia and Canada, sion is remarkably similar to that of the Fortescue
Group — so much so that attempts have beenand the Early Archaean to Early Proterozoic
Pilbara and Kaapvaal cratons of Western Australia made to correlate subdivisions of the two succes-
sions (e.g. Cheney et al., 1988; Grobler andand southern Africa, respectively. With the wide
acceptance of plate tectonic processes and the Meakins, 1988; Grobler et al., 1989 ). More
recently, Cheney (1996), adopting a comparativelikelihood that the Earth’s early continents may
have undergone extended histories of fragmenta- sequence stratigraphic and lithofacies approach,
compared general lithological characteristics oftion and amalgamation during many rifting and
collision cycles, these geological similarities have 2700 to 1400 Ma supracrustal sequences of the
Pilbara and Kaapvaal cratons, concluding thatbeen interpreted to indicate that the similar cratons
represent separated parts of a once-united lithostratigraphic similarities, particularly in the
2700 to 2100 Ma sequences on both cratons, indi-continent.
Alternative explanations to such ‘super-craton’ cated that they were united to form part of a single
continent, ‘Vaalbara’, during this time. Thehypotheses have also been proposed. Nelson
(1998a) argued that, due to subtle differences in Zimbabwe Craton was also considered to have
been amalgamated with Vaalbara during thethe timing of structural and magmatic events in
the granite–greenstone terranes of the Yilgarn and Limpopo Orogeny at ca 2470 Ma. Rifting of the
Pilbara Craton from the southern edge of theSuperior cratons, these cratons could not represent
fragments of a single Late Archaean ‘super- western part of the Kaapvaal Craton was inferred
to have occurred at ca 1300 Ma (Cheney, 1996 ).craton’. Similarities in the lithologies, stratigraphic
associations and structural and metamorphic his- In this contribution, the Archaean and Early
Proterozoic geological histories of the Pilbara andtories of the granite–greenstone terranes of the
southern part of the Superior Craton and the Kaapvaal cratons are summarised in detail, and
the available evidence that these cratons onceeastern part of the Yilgarn Craton were instead
attributed to the operation of abrupt, global-scale formed part of a single united craton is assessed.
The approach adopted here makes use of compari-magmatic episodes that were superimposed on
plate tectonic processes during the Late Archaean. sons of detailed chronologies, determined mainly
using precise U–Pb zircon analysis, of similarThe early geological development of the Pilbara
and Kaapvaal cratons extended over a period of geological events on the two cratons. This
approach is based on the reasoning that, if dis->1 Ga, and has many features in common. Both
are broadly divisible into an older granite–green- persed cratons are random fragments of a once-
united craton, then short-lived tectonic events, andstone terrane, formed between 3.5 and 3.0 Ga, and
a younger volcano-sedimentary cover. Within the particularly magmatic and deformation events,
should be recognisable on both continentalPilbara Craton the cover sequence includes the
volcanic and clastic sedimentary rocks of the fragments.
For convenience, the Pilbara and KaapvaalFortescue Group, extensive shales and banded
iron-formations of the overlying Hamersley Group cratons have been subdivided into granite–green-
stone basement and supracrustal cover compo-and the clastic sedimentary rocks of the Turee
Creek Group (see Fig. 1). The equivalent nents, which are separated on both cratons by
widespread erosion surfaces. However, it is hereVentersdorp and Transvaal Supergroups of the
Kaapvaal Craton are lithostratigraphically closely acknowledged that distinguishing between these

167D.R. Nelson et al. /Precambrian Research 97 ( 1999) 165–189
Fig. 1. Simplified regional geological map of the Pilbara Craton. Numbered geochronology sampling localities refer to entries in
Table 1 and reference numbers in Figs. 3 and 4.
two components is not simple in practice, due to ties, are shown in Fig. 1. A compilation of high-
quality geochronology (mostly U–Pb zircon) datathe existence of sequences (e.g. the Whim Creek
Group of the Pilbara Craton) that have transi- is given in Table 1. A substantial amount of new
U–Pb zircon geochronological data has recentlytional characteristics.
become available for the Pilbara Craton. In sup-
port of a detailed mapping program, >70 new
SHRIMP U–Pb zircon dates have recently been2. Pilbara Craton
obtained for a wide range of lithologies from sites
dispersed throughout the craton (Nelson, 1997,The simplified geology of the Pilbara Craton,
and U–Pb zircon geochronology sampling locali- 1998b, 1999). Although this work is currently still

168 D.R. Nelson et al. /Precambrian Research 97 ( 1999) 165–189
Fig. 2. Simplified regional geology of the Kaapvaal Craton. Numbered geochronology sampling localities refer to entries in Table 1
and reference numbers in Figs. 3 and 4.
in progress, these new data have delineated a 2.1. Chronology of granite–greenstone crust
number of major magmatic events in both granite– formation in the Pilbara Craton
greenstone and supracrustal components, and indi-
The chronology of (mainly magmatic) events
cate that important geological differences exist
within the granite–greenstone component of the
between the eastern and western parts of the
Pilbara Craton. Pilbara Craton is summarised in Fig. 3. That

169D.R. Nelson et al. /Precambrian Research 97 ( 1999) 165–189
Table 1
Compilation of (mainly U–Pb zircon) geochronology data for the Pilbara and Kaapvaal cratons; the entries for each craton are listed
in order of descending age and the reference numbers cited refer to localities shown in Figs. 1 and 2 and reference numbers shown
in Figs. 3 and 4
Reference Sample Sample Age ±Reference
No. No. details
A. Pilbara Craton
1 142870 Banded gneiss, 6 mile Well 3655 6 Nelson (1999 )
2 70601 Brecciated hyaloclastic rhyolite, Coonterunah 3515 3 Buick et al. (1995 )
3 Grey tonalitic gneiss, Tamborah 3485 30 Williams et al. (1983 )
4 153188 Monzogranite, Wilson Well 3484 4 Nelson (1999)
5 Grey tonalitic gneiss, Tamborah 3470 25 Williams et al. (1983 )
6 142828 Heterogeneous granodiorite gneiss, Fred Well 3470 4 Nelson ( 1998b )
7 148500 Lapilli tuff, Scotty Well 3469 3 Nelson (1999)
8 153190 Monzogranite, Shilliman Well 3469 2 Nelson (1999)
9 T94/227 Mylonitized granite, Split Rock Shear Zone 3469 3 Zegers (1996 )
10 T94/193 Granodiorite, Split Rock Shear Zone 3468 3 Zegers (1996 )
11 94058 Porphyritic microgranite, Carlindi 3468 4 Buick et al. (1995)
12 uwa98076 Intermediate pyroclastic rock, Duffer Formation 3466 4 McNaughton et al. (1993 )
13 142865 Alkali granite, Marble Bar Road 3466 2 Nelson (1998b)
14 100515 Felsic schist, Yandicoogina, Duffer Formation 3465 3 Thorpe et al. ( 1992)
15 T94/222 Diorite, central part of Shaw Granitoid Complex 3463 2 Zegers (1996 )
16 100510 Monzogranite, North Pole 3459 18 Thorpe et al. ( 1992 )
17 100507 Felsic volcanic rock, Panorama Formation 3457 3 Thorpe et al. (1992 )
18 anu76324 Dacite, Duffer Formation, Glen Herring 3452 16 Pidgeon ( 1978a)
19 94770 Felsic schist, Salgash Subgroup, West Bamboo 3452 3 Thorpe et al. ( 1992 )
20 T94/221 Grey gneiss, central part of Shaw Granitoid Complex 3451 1 Zegers (1996)
21 103283 Miralga Creek porphyry, North Pole 3449 2 Thorpe et al. ( 1992)
22 94750 Felsic schist, Mount Ada Basalt, Pyramid Well 3449 3 Thorpe et al. (1992 )
23 ltu6419 Mafic trondhjemitic gneiss, Chinaman Creek 3448 8 Williams and Collins ( 1990)
24 142878 Foliated biotite monzogranite, Hillside Track 3445 3 Nelson ( 1998b )
25 ltu6417 Felsic trondhjemitic gneiss, Chinaman Creek 3443 10 Williams and Collins ( 1990)
26 124755 Biotite granodiorite, Sunrise Hill West 4 pit 3443 6 Nelson ( 1997 )
27 143807 Tonalite, Kennedy Gap 3438 4 Nelson (1998b )
28 uwa98053 Granodiorite, South Daltons Pluton 3431 4 McNaughton et al. ( 1993)
29 MP1 Dacite, McPhee Dome 3430 3 Barley et al. ( 1998)
30 ltu5416 Banded tonalitic gneiss, Mount Edgar Granitoid Complex 3429 13 Williams and Collins ( 1990)
31 142836 Volcaniclastic sediment, Gorge Creek 3426 10 Nelson (1998b )
32 142170 Foliated biotite monzogranite, Kangan Homestead 3421 2 Nelson ( 1999)
33 K1 Rhyodacite, Spinaway Creek, Kelly Belt 3417 9 Barley et al. ( 1998 )
34 Gneissic migmatite, Shaw Granitoid Complex 3417 40 Pidgeon ( 1978b)
35 143995 Quartzite, Friendly Stranger Mine 3403 10 Nelson (1998b )
36 143996 Quartzite, Shay Gap 3398 15 Nelson ( 1998b)
37 143994 Quartzite, Kittys Gap 3362 13 Nelson ( 1998b)
38 uwa98074 Porphyritic rhyolite, Wyman Formation, Badjan Creek 3325 4 McNaughton et al. ( 1993)
39 94754 Rhyolite,Wyman Formation, Emu Creek 3325 3 Thorpe et al. ( 1992)
40 ltu5577 Granodiorite, Coppin Gap 3314 13 Williams and Collins ( 1990 )
41 143803 Biotite granodiorite, Don Well 3313 3 Nelson (1998b)
42 143809 Biotite monzogranite, Ngarrin Creek 3313 6 Nelson ( 1998b)
43 77713 Boobina porphyry 3307 19 Pidgeon ( 1984)
44 ltu5472 Tonalite, Boodalla Suite 3304 10 Williams and Collins ( 1990)
45 142871 Porphyritic biotite granodiorite, Granite Well 3303 5 Nelson (1999 )
46 143806 Biotite monzogranite, Yundinna Creek 3303 2 Nelson (1998b)
47 Foliated granodiorite, Mount Edgar Granitoid Complex 3280 20 Pidgeon ( 1978b)
48 142433 Tonalite, Mount Regal 3270 2 Nelson (1998b)
49 136819 Quartz-mica schist, Lydia Mine 3269 2 Nelson (1998b)
50 N4438 Granite, Karratha Industrial Area 3267 4 Smith (1999 )
51 JS43 Granodiorite, Harding Complex, Water Authority Road 3265 4 Smithies et al. ( 1999)
52 JS17 Karratha Granite, southern margin of Complex 3261 4 Smithies et al. ( 1999 )
53 N3214 Granodiorite, South Ruth Well 3258 12 Smith ( 1999)
54 143805 Biotite monzogranite, Near Home Well 3252 3 Nelson (1998b)
55 118975 Porphyritic rhyolite, Mount Regal 3251 6 Nelson (1997)

170 D.R. Nelson et al. /Precambrian Research 97 ( 1999) 165–189
Table 1
(continued)
Reference Sample Sample Age ±Reference
No. No. details
56 142869 Porphyritic biotite granodiorite, 6 mile Well 3244 3 Nelson ( 1999)
57 143810 Foliated porphyritic biotite monzogranite, Wolline Well 3244 3 Nelson (1998b)
58 142874 Granodiorite, Ninety Mile 3242 4 Nelson (1999)
59 142535 Foliated hornblende–biotite tonalite, Tarlwa Pool 3236 3 Nelson ( 1998b )
60 N4325 Rhyolite, Tozers Track 3128 6 Smith (1999 )
61 114350 Metadacite, Mount Sholl 3125 4 Nelson (1997)
62 N4357 Rhyolite, Whundo 3124 4 Smith ( 1999 )
63 114358 Porphyritic rhyolite, south of Mount Sholl 3122 7 Nelson (1997)
64 N4413 Rhyolite dyke, Horsehoe Valley 3121 2 Smith (1999)
65 144256 Rhyolite tuff, De Witt Hill 3118 2 Nelson (1998b )
66 114356 Rhyolite, south of Mount Sholl 3118 3 Nelson ( 1997)
67 127378 Welded tuff, Woodbrook Homestead 3117 3 Nelson (1998b)
68 144210 Rhyodacite, Mount Fisher 3116 3 Nelson ( 1998b)
69 114305 Bedded felsic tuff, east of Mount Sholl 3115 5 Nelson (1997 )
70 JS33 Granodiorite, Chiratta Granitoid Complex, Whundo south 3114 5 Smithies et al. ( 1999 )
71 JS20 Granite, north of Sholl belt 3114 5 Smithies et al. (1999 )
72 W197 Felsic tuff, Sholl belt 3112 6 Horwitz and Pidgeon (1993 )
73 142835 Tonalitic gneiss, Whundo 3107 9 Nelson (1999)
74 118965 Biotite monzogranite gneiss, old hwy-Sherlock River 3093 4 Nelson ( 1997)
75 142661 Foliated biotite tonalite, Zebra Hill 3068 4 Nelson (1998b)
76 127330 Volcaniclastic sediment, Cleaverville 3058 7 Nelson ( 1998b)
77 142867 Porphyritic trachytic tuff, Cattle Well 3048 19 Nelson (1999 )
78 JS25 Mylonitized granite, Sholl Shear Zone 3024 4 Smithies et al. (1999)
79 118976 Porphyritic dacite, Chiratta Road–Nickol River crossing 3023 9 Nelson (1997 )
80 144244 Dacite porphyry, Mount Wangee 3021 3 Nelson (1999)
81 N4097 Granodiorite, 11 Mile Well 3018 5 Smith (1999 )
82 127327 Dacite porphyry, Rocky Creek 3018 2 Nelson (1998b )
83 142830 Volcanigenic sediment, Mount Ada 3018 3 Nelson (1998b)
84 N3188 Porphyry, Copper Pit -Agip 3016 3 Smith ( 1999)
85 N4028 Porphyry, Copper Pit 3016 5 Smith ( 1999)
86 142842 Volcaniclastic sediment, Nunyerry Gap 3016 13 Nelson ( 1998b)
87 136899 Volcanigenic sediment, Wickham 3015 5 Nelson ( 1998b )
88 127320 Quartz granophyre, Mount Ada 3014 6 Nelson ( 1997)
89 118979 Quartz–feldspar porphyry, No. 6 Well 3014 2 Nelson (1997 )
90 118966 Porphyritic granodioritic gneiss, Forrestier Bay 3014 3 Nelson (1997)
91 JS35 Granite, Sholl belt 3013 4 Smithies et al. ( 1999)
92 N4128 Granodiorite, Ruth Well Costean 3010 3 Smith (1999)
93 141936 Welded tuff, Red Hill 3009 4 Nelson (1998b )
94 136844 Granite, Dampier Salt Ponds 2997 3 Nelson (1998b)
95 118969 Fine-grained greywacke sandstone, May Bore 2996 9 Nelson ( 1997 )
96 118974 Porphyritic hornblende granodiorite, Baynton Hill 2994 2 Nelson (1997 )
97 142438 Granodiorite, Elizabeth Hill 2988 4 Nelson ( 1999 )
98 N3132 Granodiorite, Chiratta Granitoid Complex 2986 6 Smith ( 1999)
99 144261 Rhyolite, Bradley Well 2975 4 Nelson ( 1998b )
100 142430 Monzogranite, Andover Complex, Black Hill Well 2970 5 Nelson ( 1999 )
101 142657 Granodiorite, Cadgerina Pool 2966 9 Nelson (1999)
102 142893 Pegmatite-veined monzogranite, Marda Well 2952 6 Nelson ( 1999)
103 118967 Equigranular hornblende–biotite tonalite, Ten Foot Well 2948 5 Nelson ( 1997 )
104 142889 Foliated alkali granite, Roberts Hill 2946 6 Nelson (1999)
105 136826 Biotite–hornblende tonalite gneiss, Toorare Pool 2944 5 Nelson (1997)
106 142892 Quartz–feldspar porphyry, 2 mile Well 2941 4 Nelson ( 1999)
107 142188 Subarkose, Egina Well 2941 9 Nelson ( 1999 )
108 142176 Biotite monzogranite, Yandeyarra Homestead 2938 3 Nelson (1999)
109 141973 Biotite monzogranite, Wakeman Well 2938 4 Nelson ( 1998b )
110 T94/31 Granite, Mulgandinnah Shear Zone 2934 2 Zegers (1996 )
111 142884 Schleric biotite syenogranite, Mount Webber 2933 3 Nelson ( 1998b)
112 141977 Granite, Manyon Well 2931 5 Nelson ( 1998b )
113 N3162 Granite, North Whundo 2929 5 Smith (1999)
114 N4450 Granite, south of Radio Hill 2929 7 Smith ( 1999)

171D.R. Nelson et al. /Precambrian Research 97 ( 1999) 165–189
Table 1
(continued)
Reference Sample Sample Age ±Reference
No. No. details
115 142882 Biotite monzogranite, west of Mulgandinna Hill 2928 2 Nelson (1998b)
116 142885 Biotite monzogranite, Mundine Well 2927 3 Nelson (1998b )
117 103227 Magnetite ferrogabbro pegmatite, Munni Munni Complex 2925 16 Arndt et al. (1991 )
118 118964 Foliated granite, Caines Well 2925 4 Nelson (1997)
119 142436 Micromonzonite dyke, Munni Munni Complex 2924 5 Nelson (1998b)
120 142883 Porphyritic syenogranite dyke, south of Mulgandinna Hill 2919 3 Nelson (1998b )
121 142879 Biotite monzogranite, Cooglegong Creek 2851 2 Nelson (1998b)
122 86738 Felsic volcanic rock, near base of Mount Roe Basalt 2775 10 Arndt et al. (1991 )
123 77712 Spinaway porphyry 2768 16 Pidgeon ( 1984)
124 118972 Porphyritic biotite monzogranite, Opaline Well 2765 5 Nelson (1997 )
125 94759 Rhyolite, Koongaling Volcanic Member 2764 8 Arndt et al. ( 1991)
126 94792 Lapilli tuff, base of Mount Roe Basalt 2763 13 Arndt et al. ( 1991 )
127 118923 Granophyre, Nifty Access Road 2763 8 Nelson (1997)
128 118920 Alkali granite, Walla Rock 2762 4 Nelson (1997 )
129 118925 Monzogranite, Lookout Rocks 2761 2 Nelson ( 1999)
130 94760 Rhyolite porphyry sill, Warri Warri Creek 2760 10 Arndt et al. (1991)
131 142875 Porphyritic monzogranite dyke, Simpson Well 2758 4 Nelson ( 1999)
132 142825 Coarse-grained syenite, No. 3 Well 2757 7 Nelson (1998b )
133 118924 Hornblende–biotite granite augen gneiss, Esso Track 2757 5 Nelson (1997 )
134 94761 Porphyry, Bamboo Creek 2756 8 Arndt et al. (1991)
135 144993 Dacite, Booloomba Pool 2717 2 Nelson (1998b )
136 94775 Tuffaceous sandstone, Pillingini Tuff, Tumbiana Formation 2715 6 Arndt et al. ( 1991)
137 103225 Tuffaceous sandstone, Jeerinah Formation, Parabadoo 2690 16 Arndt et al. (1991)
138 94776 Tuffaceous sandstone, Jeerinah Formation, Nallanaring 2684 6 Arndt et al. ( 1991 )
139 120048 Andesitic ignimbrite, top of Jeerinah Formation 2629 5 A.F. Trendall (unpublished data)
140 120046 NS3, Mt Newman Member, Marra Mamba 2597 5 Trendall et al. (1998 )
141 120044 Crystal-rich tuff, Wittenoom Formation 2561 8 Trendall et al. (1998 )
142 120051 S9, Dales Gorge Member 2479 3 A.F. Trendall (unpublished data)
143 120058 Whaleback Shale Member 2463 5 A.F. Trendall (unpublished data)
144 W17 Woongarra Rhyolite, Woongarra Gorge 2449 3 Barley et al. ( 1998 )
145 W12 Weeli Wolli Formation, Cathedral Gorge 2449 3 Barley et al. ( 1998 )
B. Kaapvaal Craton
151 AGC 150 Tonalitic gneiss, Ancient Gneiss Complex 3644 4 Kro
¨ner and Compston (1988)
152 MD 6 Granite pebble in Moodies Conglomerate 3570 6 Kro
¨ner and Compston (1988)
153 BA 49 Shistose tuff, Theespruit Formation 3548 3 Kro
¨ner et al. (1996 )
154 SA 414-2 Shistose tuff, Theespruit Formation 3548 1 Kro
¨ner et al. (1996 )
155 BA 39 Tuff, Theespruit Formation 3547 2 Kro
¨ner et al. (1996 )
156 BA 40 Shistose tuff, Theespruit Formation 3547 2 Kro
¨ner et al. (1996 )
157 BB 03/86 Tonalitic gneiss, Theespruit Formation 3538 6 Armstrong et al. (1990 )
158 A Tonalite gneiss, Theespruit Formation 3538 4 Kamo and Davis (1994 )
159 MD 251 Granite pebble in Moodies Conglomerate 3531 4 Kro
¨ner and Compston (1988)
160 C 48 Granite pebble in Moodies Conglomerate 3518 11 Kro
¨ner and Compston (1988)
161 BA 48 Trondhjemite, Steynsdorp Pluton 3510 4 Kro
¨ner et al. (1996 )
162 B Steynsdorp Pluton 3509 8 Kamo and Davis ( 1994)
163 BA-26 Trondhjemite 3505 5 Kro
¨ner et al. (1996 )
164 AGC 150 Component in tonalitic gneiss 3504 6 Compston and Kro
¨ner (1988 )
165 BA 41 Steynsdorp Pluton granodiorite 3502 2 Kro
¨ner et al. (1996 )
166 B-Gab 08/86 Metagabbro, Komati Formation 3482 5 Armstrong et al. ( 1990)
167 Samples 8 and 9 Volcaniclastic sediment 3472 5 Armstrong et al. ( 1990)
168 C Quartz–feldspar porphyry dyke 3470 39 Kamo and Davis ( 1994)
169 SWA 53 Greywacke, Fig Tree Group 3461 16 Kro
¨ner and Compston (1988)
170 D Stolzburg Pluton 3460 5 Kamo and Davis ( 1994)
171 BBC 04/86 Volcaniclastic sediment, Theespruit Formation 3453 6 Armstrong et al. ( 1990)
172 SA351-2 Hooggenoeg Formation 3452 3 Byerly et al. (1996 )
173 BA 46 Vlakplaats granodiorite 3450 3 Kro
¨ner et al. (1996 )
174 E Doornhoek Pluton 3448 4 Kamo and Davis ( 1994)
175 BSV 30/86 Felsic volcanic rock, Hooggenoeg Formation 3445 8 Armstrong et al. ( 1990 )
176 SA351-2 Hooggenoeg Formation 3445 3 Kro
¨ner et al. (1991 )
177 F Theespruit Pluton 3443 4 Kamo and Davis (1994 )

172 D.R. Nelson et al. /Precambrian Research 97 ( 1999) 165–189
Table 1
(continued)
Reference Sample Sample Age ±Reference
No. No. details
178 BG 04/86 Trondhjemite, Theespruit Pluton 3437 6 Armstrong et al. ( 1990)
179 MW64 Kromberg Formation 3416 5 Kro
¨ner et al. (1991 )
180 G Gabbro, Komati Formation 3352 6 Kamo and Davis (1994 )
181 MW19 Kromberg Formation 3334 6 Byerly et al. ( 1996)
182 P Xenolith, Nelspruit Pluton 3304 6 Kamo and Davis ( 1994)
183 SA167 Mendon Formation 3298 6 Byerly et al. ( 1996)
184 SA310-1 Fig Tree Group 3258 3 Byerly et al. ( 1996)
185 SA224-1 Fig Tree Group 3256 4 Kro
¨ner et al. (1991 )
186 SA201-1 Fig Tree Group 3253 3 Byerly et al. ( 1996)
187 AGC-26 Stentor Tonalitic Pluton 3250 30 Tegtmeyer and Kro
¨ner (1987 )
188 SA326 Fig Tree Group 3243 3 Byerly et al. ( 1996)
189 SA413-1 Fig Tree Group 3237 3 Byerly et al. ( 1996)
190 L Deformed quartz–feldspar porphyry 3229 4 Kamo and Davis (1994)
191 I Kaap Valley Pluton 3228 2 Kamo and Davis ( 1994)
192 94-5 French Bob’s Granite 3228 12 Poujol et al. ( 1997)
193 H Kaap Valley Pluton 3227 1 Kamo and Davis ( 1994 )
194 LH842 Fig Tree Group 3227 5 Kro
¨ner et al. (1991 )
195 Z262 Tonalite, Kaap Valley Pluton 3226 14 Armstrong et al. ( 1990 )
196 J Ignimbrite 3226 1 Kamo and Davis ( 1994)
197 K Feldspar porphyry 3222 10 Kamo and Davis ( 1994)
198 M Dalmein Pluton 3216 2 Kamo and Davis ( 1994)
199 95-16 Weigel Formation volcanics 3196 28 Poujol et al. (1997)
200 Nelshoogte Pluton 3180 75 Barton et al. ( 1983)
201 94-9 Mac Kop conglomerate 3168 11 Poujol et al. (1997 )
202 DRL-7 Granite, basement to Witwatersrand Group 3120 5 Armstrong et al. (1991 )
203 U Salisbury Kop Pluton 3109 10 Kamo and Davis ( 1994)
204 R Stentor Pluton 3107 5 Kamo and Davis ( 1994)
205 S Mpuluzi Pluton 3107 4 Kamo and Davis ( 1994 )
206 T Boesmanskop Pluton 3107 2 Kamo and Davis ( 1994)
207 O Nelspruit Pluton 3106 3 Kamo and Davis ( 1994)
208 Detrital zircons in Dominion Group 3105 3 Robb et al. (1990)
209 Q Hebron Pluton 3104 3 Kamo and Davis ( 1994)
210 DRL-13/B Quartz–feldspar porphyry 3074 6 Armstrong et al. (1991 )
211 Detrital zircons in West Rand Group 3060 2 Robb et al. (1990 )
212 Coligny-Ottosdal granite 3031 11 Robb et al. ( 1992 )
213 Pongola Supergroup 2985 1 Hegner et al. (1994)
214 94-3 Rubbervale Formation rhyolite 2971 10 Poujol et al. ( 1997)
215 Murch 94-11 Malati Pump mine granodiorite 2970 15 Poujol et al. ( 1997)
216 Rubbervale Formation rhyolite 2967 2 Brandl et al. ( 1996)
217 Murch 94-13 Discovery Mine granite 2960 43 Poujol et al. (1997)
218 PO 87 Rhyolite, Pongola Supergroup 2940 22 Hegner et al. ( 1984)
219 Turffontein, Central Rand Group 2909 3 Robb et al. (1990 )
220 94-12 Maranda granite 2901 20 Poujol et al. (1997)
221 Schweizer–Reneke granites 2882 2 Robb et al. ( 1992 )
222 UP 11 Pyroxenite, Usushawana Intrusive Complex 2871 30 Hegner et al. (1984)
223 Kraaipan granodiorite 2846 22 Anhaeusser and Walraven (1997 )
224 Murch 94-14 Willie Granite 2820 38 Poujol et al. ( 1997)
225 Kanye Volcanics 2785 2 Moore et al. ( 1993 )
226 Gaborone granophyre 2784 4 Grobler and Walraven (1993 )
227 DER52 Kanye Volcanics 2784 1 Grobler and Walraven (1993)
228 DG91313-7 Kgale Granite, Gaborone Complex 2783 2 Moore et al. (1993 )
229 DG91313-3 Kgale microgranphyre 2782 5 Grobler and Walraven (1993 )
230 Plantation Porphyry 2782 2 Walraven et al. ( 1996)
231 Felsite, Derdepoort Basalt 2781 5 Wingate (1997 )
232 KV16-2 Kanye volcanics 2779 3 Grobler and Walraven (1993 )
233 DG91313-6 Kgale granophyre, Gaborone Complex 2771 26 Moore et al. ( 1993 )
234 Mosita adamellite 2749 3 Anhaeusser and Walraven (1997 )
235 W Mpageni Pluton 2740 15 Kamo and Davis ( 1994)
236 94-6 Rooiwater Complex tonalite 2740 4 Poujol et al. ( 1997)
237 EK-4/5 & Z320 Klipriviersberg Group 2714 8 Armstrong et al. ( 1991 )

173D.R. Nelson et al. /Precambrian Research 97 ( 1999) 165–189
Table 1
(continued)
Reference Sample Sample Age ±Reference
No. No. details
238 ZFL-1 Kareefontein Quartz Porphyry 2714 3 Walraven et al. (1991 )
239 FW83Va Makwassie Quartz porphyry 2709 4 Armstrong et al. ( 1991)
240 MBE/C Mbabane Pluton, Swaziland 2687 6 Layer et al. ( 1989)
241 Murch 94-8 Mashishimala Suite granite 2677 14 Poujol et al. ( 1997)
242 Vryburg Formation (Schmidtsdrif ) 2642 3 Walraven et al. ( 1999)
243 WA93/15 Middle Nauga Formation 2588 6 Altermann and Nelson ( 1998)
244 Oak Tree Formation 2583 5 Martin et al. ( 1999 )
245 WA93/41 Upper Monteville Formation 2555 11 Altermann and Nelson ( 1998 )
246 Nauga Formation 2552 11 Barton et al. (1994 )
247 Oak Tree Formation 2550 3 Walraven and Martini (1995)
248 WA93/12 Upper Nauga Formation 2549 7 Altermann and Nelson ( 1998)
249 Alphen farm Campbellrand-Kuruman 2521 3 Sumner and Bowring (1996)
250 WA92/4 Upper Gamohaan Formation 2516 4 Altermann and Nelson (1998 )
251 120004 Griquatown Iron Formation, 18 m above base 2489 33 A.F. Trendall (unpublished data)
252 120008 Penge Iron Formation 2480 6 A.F. Trendall (unpublished data)
253 near top of Kuruman Iron Formation 2465 7 R.A.Armstrong, in Martin et al. (1998 )
254 Kuruman/Griquatown boundary 2432 31 W. Compston, in Trendall et al. ( 1990 )
Fig. 3. Comparison of the chronology of magmatic episodes within the Pilbara and Kaapvaal cratons. Dates for volcanic and
sedimentary rocks (#) are distinguished from those for intrusive (mostly granitoid ) rocks (n). Error bars where shown are at 95%
confidence level. Where not shown, 95%confidence error bars are comparable in size to, or smaller than, the plotted symbol. Reference
numbers refer to those listed in Table 1. Magmatic episodes within the Pilbara Craton (shown as shaded bars): 3470 to 3400 Ma
Warrawoona episode, confined to the eastern Pilbara; 3325 to 3290 Ma Wyman episode, confined to the eastern Pilbara; 3270 to
3235 Ma Roebourne episode, craton-wide; 3140 to 3090 Ma Sholl episode, confined to the western Pilbara; 3025 to 2950 Ma Mallina
episode, craton-wide; 2950 to 2910 Ma Millindinna episode, craton-wide, and 2760 Ma early Fortescue episode, craton-wide. Magmatic
episodes within the Kaapvaal Craton: 3560 to 3440 Ma Onverwacht episode, Barberton; 3250 to 3220 Ma Kaap Valley episode,
Murchison and Barberton; 3120 to 3100 Ma Mpuluzi episode, Barberton, a poorly-defined episode at 2985 to 2960 Ma, Murchison
and Pongola Supergroup, and 2782 Ma Gaborone –Kanye–Plantation Porphyry–Derdepoort episode, northwestern part of
Kaapvaal Craton.

174 D.R. Nelson et al. /Precambrian Research 97 ( 1999) 165–189
growth of the granite–greenstone crust of the rently abrupt episode at 2940 to 2920 Ma through-
out the Shaw and Yule Granitoid Complexes incraton occurred episodically is clearly shown by
this diagram, with magmatism concentrated within the western part of the east Pilbara region, and in
the west Pilbara region. Apart from the emplace-intervals of <10 to 70 Ma at ca 3470 to 3400,
3325 to 3290, 3270 to 3235, 3140 to 3090, 3025 to ment of the Cooglegong monzogranite into the
Shaw Granitoid Complex at ca 2850 Ma, the ca2990, 2950 to 2910 and at 2760 Ma. The oldest
dates from the Pilbara Craton have been obtained 2930 Ma episode is the last widespread magmatic
event recorded within the granitoid complexes offor 3655±6 and 3637±12 Ma (all errors cited
herein are at 95%confidence unless otherwise the Pilbara Craton prior to the emplacement of
the Fortescue Group. It is conceivable that theindicated) components within a composite banded
gneiss from the Warrawagine Granitoid Complex characteristic geometry of the granite–greenstones
evident in the eastern part of the Pilbara Craton,(Nelson, 1999). In the eastern part of the Pilbara
Craton, the 3515±3 Ma Coonterunah succession with anticlinal granitoid complexes surrounded by
greenstones preserved within marginal synclines,identified by Buick et al. (1995 ), unconformably
below the Warrawoona Group greenstones, repre- was imposed by late-stage tectonism at ca 2930 or
2850 Ma. However, despite comparatively inten-sents the oldest greenstone sequence so far recog-
nised in the craton. Widespread and apparently sive data coverage, no ca 2930 or 2850 Ma granitic
rocks have been identified within the Muccan andcontinuous emplacement of both granitic and vol-
canic rocks is recorded throughout the eastern part Warrawagine Granitoid Complexes in the north-
eastern part of the east Pilbara, even though theof the Pilbara Craton between 3470 and 3400 Ma.
Maximum depositional ages obtained by the dating pre-2930 Ma histories of both regions are similar
(i.e. rocks emplaced during 3470 to 3400 Ma, 3325of detrital zircons in three samples of clastic met-
asedimentary rock, from sites located around the to 3290 Ma and 3270 to 3235 Ma events are present
in both granitoid complexes). This suggests thatmargins of the Muccan Granitoid Complex and
immediately below a regionally extensive banded the domal granite and arcuate greenstone distribu-
tion is an original (pre-2930 Ma) feature that wasiron-formation, indicate that these sequences were
probably deposited after ca 3350 Ma, largely con- not extensively modified by younger (i.e.
∏3235 Ma) events.formably onto the older volcanic successions.
Further extensive volcanic and granitic emplace- The stratigraphy of the greenstones of the west-
ern part of the Pilbara Craton was recently revisedment events took place in the eastern part of the
Pilbara Craton between ca 3325 and 3290 Ma, and by Hickman ( 1998) in the light of recent geological
mapping and new geochronology. Rocks olderat 3270 to 3235 Ma throughout the eastern and
western parts of the craton, followed by the wide- than 3275 Ma have yet to be identified in the west
Pilbara. The 3270 to 3250 Ma volcanic, clastic andspread deposition of clastic sediments and banded
iron-formation. In contrast to the west Pilbara, chemical sedimentary rocks of the (newly defined )
Roebourne Group, and the ca 3260 Ma graniticthe eastern part of the Pilbara Craton appears to
have undergone a period of tectonic quiescence rocks of the Karratha Granodiorite, are the oldest
rocks so far recognised in the western part of thebetween 3230 and 2930 Ma, with the volumetri-
cally minor tuffaceous sedimentary rocks of the Pilbara Craton. These occur both to the north (i.e.
the 3251±6 Ma rhyolite and 3270±2 Ma tonaliteCattle Well Formation providing the only evidence
of igneous activity so far recognised in the eastern at Mount Regal ) and south ( i.e. the 3236±3Ma
foliated biotite tonalite at Tarlwa Pool) of a majorpart of the craton during this period. Either there
was a hiatus in the geological development of the east-trending structure, the Sholl Shear Zone, that
has been interpreted as a major terrane boundaryeastern Pilbara during this interval, the rocks
formed during this time were volumetrically minor (e.g. Krapez, 1993). They may be correlatives of
the 3270 to 3235 Ma volcanic and granitic rocksin extent and have yet to be identified, or they
were subsequently removed by erosion. of the eastern part of the Pilbara Craton. To the
south of the Sholl Shear Zone, the dominantlyGranitoid rocks were emplaced during an appa-

175D.R. Nelson et al. /Precambrian Research 97 ( 1999) 165–189
volcanic Whundo Group has been dated at 3125 in the east Pilbara, but clastic sediments of the ca
3010 Ma De Grey Group occur across the craton,to 3112 Ma, with granitic rocks emplaced within
the Caines Well Granitoid Complex at 3095 Ma. indicating that the eastern and western parts of
the craton were united by this time.The ca 3020 Ma Cleaverville Formation, consisting
of banded iron-formation, chert, fine-grained clas- An intriguing feature of the regional geochro-
nology data obtained for the Pilbara granite–tic sedimentary and minor felsic volcanic rocks,
overlies both the Roebourne Group north of the greenstones is that all major granite–greenstone
crust-forming magmatic events at ca 3470 to 3400,Sholl Shear Zone and the Whundo Group to the
south. The Cleaverville Formation is unconform- 3325 to 3290, 3270 to 3235, 3140 to 3090, 3025 to
2990 and 2950 to 2910 are characterized by periodsably overlain by basaltic lava, felsic tuffand clastic
sedimentary rocks of the ca 3010 Ma Whim Creek of apparently continuous magmatic (intrusive and
commonly, extrusive) activity of 30–70 Ma dura-Group and the regionally extensive clastic sedi-
mentary rocks of the ca 3010 Ma Mal- tion, manifest over regions (as opposed to linear
belts) of >100 km2. Emplacement of intrusivelina Formation. Recent geochronological work
(Nelson, 1999) has confirmed that the Cattle Well (mostly granitic) and extrusion of volcanic ( both
felsic and mafic ) rocks occurred synchronouslyFormation of the east Pilbara is probably a correla-
tive of either the Cleaverville Formation or De during these events, although emplacement of
granitoid plutons commonly continued for someGrey Group [as reinterpreted by Smithies et al.
(1999), to include the Whim Creek Group] in the time following eruption of the volcanic rocks, and
volcanic rocks have yet to be identified for thecentral and western parts of the Pilbara Craton.
The Whim Creek Group is unconformably over- 2950 to 2910 Ma event. The regional distribution
and long duration of each of these events arelain by mafic volcanic rocks of the Louden
Volcanics, which are in turn overlain by the features atypical of rift/collision processes. Instead,
events following the first magmatic event betweenKialrah Rhyolite (Smithies et al., 1999). A feld-
spar-phyric, flow-banded rhyolite from the Kialrah 3470 and 3400 Ma appear to have magmatically
reworked the crust formed during the earlierRhyolite, sampled south of Roebourne, has
been dated at ca 2970 Ma ( Nelson, 1998b ). events, over extensive regions rather than along
elongate orogenic belts.Emplacement of ultramafic complexes, such as the
Munni Munni, Radio Hill, Mount Sholl, Dingo
and Andover complexes in the western part of the 2.2. Supracrustal sequences of the Pilbara Craton
Pilbara Craton, occurred synchronously with an
abrupt granitic intrusion episode in the eastern The chronostratigraphy of the supracrustal
sequences of the Pilbara Craton is summarised inpart of the Pilbara Craton between 2930 and
2920 Ma. Fig. 4. Identification of 3030 to 2950 Ma clastic
sedimentary sequences of the De Grey GroupThat equivalents of the oldest rocks in the west
Pilbara, the ca 3270 to 3240 Ma Roebourne Group throughout the eastern and western parts of the
Pilbara Craton provides evidence of a widespread,sequences and granitoid rocks of similar age, occur
in the east Pilbara suggests that the western and probably craton-wide, exhumation and erosion of
the craton from at least that time. Although youn-eastern parts of the Pilbara granite–greenstone
crust had commenced a common geological devel- ger rocks, such as the widespread ca 2930 to
2925 Ma volcanic, granitic and ultramafic rocks ofopment history at or shortly before 3270 Ma. This
may mark the time at which the newly-formed the western Pilbara, and emplacement of the ca
2850 Ma Cooglegong monzogranite within thewest Pilbara granite–greenstone crust had accreted
(by whatever means) to the western margin of an Shaw Granitoid Complex, post-date this time,
these are not in contact with any of the youngerolder east Pilbara nucleus. Greenstone sequences
and intrusive rocks formed during emplacement layered sequences and it is not clear whether these
were exposed during later (i.e. <2925 orof the ca 3125 to 3112 Ma Whundo Group and
granites of the west Pilbara have not been identified <2850 Ma) Archaean erosional episodes or by

176 D.R. Nelson et al. /Precambrian Research 97 ( 1999) 165–189
Fig. 4. Chronostratigraphic columns for the ∏3.1 Ga supracrustal rocks of the Pilbara and Kaapvaal cratons. Second-order transgres-
sion-regression curves for the Hamersley Basin, and for the Griqualand West and Transvaal basins [based on Altermann and Nelson
(1998 )] are also shown. Numbered dates refer to those listed in Table 1. (A) Pilbara Craton — TCG, Turee Creek Group; BIF,
Boolgeeda Iron Formation; DGM, Dales Gorge Member of Brockman Iron Formation; McRS, Mount McRae Shale; MtSF, Mount
Sylvia Formation; WF, Wittenoom Formation; MMIF, Marra Mamba Iron Formation; JF, Jeerinah Formation; MB, Maddina
Basalt; TF, Tumbiana Formation; KB, Kylena Basalt; HF, Hardey Formation; MRB, Mount Roe Basalt; BF, Bellary Formation;

177D.R. Nelson et al. /Precambrian Research 97 ( 1999) 165–189
more recent, probably Phanerozoic, exhumation. 2757±7 Ma ( Nelson, 1998b) and 2758±4Ma
(Nelson, 1999 ) for monzogranitic and syeniticRemnants of the Mount Roe Basalt of the lower
part of the Fortescue Group occur scattered intrusions in the eastern part of the Pilbara Craton,
and 2765±5 Ma for a monzogranitic intrusion inthroughout the Pilbara region, indicating that
widespread erosion, presumably accompanying the western part of the craton (Nelson, 1997 ),
indicate that a widespread ca 2760 Ma magmaticsignificant uplift, of the granite–greenstone base-
ment took place prior to ca 2760 Ma. Denudation event, synchronous with the onset of eruption of
the Fortescue Group lavas, is represented through-of the granite–greenstone basement of the Pilbara
Craton therefore commenced prior to ca 3020 Ma out the Pilbara Craton. Deposition of the volcanic
rocks of the lower part of the Fortescue Groupand may have extended until ca 2760 Ma, the time
of onset of volcanism of the overlying Fortescue probably occurred during several abrupt magmatic
episodes, at ca 2760 and ca 2717 Ma, whereasGroup. On a craton-wide scale, this interval marks
the transition from development of granite–green- deposition of the shales and subordinate tuffaceous
rocks of the Jeerinah Formation of the upper partstone crust, to deposition of extensive layered
supracrustal sequences, in the Pilbara Craton. of the Fortescue Group took place over an
extended period of ca 60 Ma.Widespread erosion may have taken place during
a number of episodes throughout this period. Conformably overlying the Fortescue Group
are shales, banded iron-formations and subordi-The Fortescue Group unconformably overlies
the granite–greenstone terrane of the Pilbara nate carbonates of the Hamersley Group. The
stratigraphy and available geochronological dataCraton. It consists of up to 7 km of basalts and
minor komatiitic basalts, with subordinate felsic from the Hamersley Group was recently summar-
ised by Trendall et al. (1998; see Fig. 4 ).volcanic and clastic sedimentary rocks. Ion micro-
probe U–Pb zircon dates obtained for felsic vol- Recognition of a number of ash-fall tuffs interlay-
ered with sedimentary rocks of the Hamersleycanic rocks near the base and top of the Fortescue
Group constrain its depositional age to between Group has enabled the precise dating of units
throughout the Hamersley sequence by the U–Pbca 2765 and 2687 Ma (Arndt et al., 1991 ). These
dates are consistent with the conventional U–Pb zircon method. Deposition of the ca 2.4 km thick
Hamersley Group over a possible area of cazircon date of 2768±16 Ma obtained by Pidgeon
(1984) on the Spinaway Porphyry and with the 105km2occurred over an interval of at least
150 Ma, from >2597 to <2449 Ma.common-Pb isotopic constraints obtained by
Richards and Blockley (1984), and indicate that The uppermost Boolgeeda Iron Formation of
the Hamersley Group is conformably overlain bythe entire Fortescue Group was deposited in ca
130 Ma. In addition, a SHRIMP U–Pb zircon date siltstones, greywackes, sandstones and minor car-
bonates and diamictites of the Turee Creek Group.of 2717±2 Ma was recently obtained for a dacite
from the Maddina Formation ( Nelson, 1998b ). These units are well exposed only within the Wyloo
Dome and Brockman, Turner, Hardey and TureeSHRIMP U–Pb zircon dates of 2763±8, 2757±5,
2757±5 Ma ( Nelson, 1997 ) and 2761±2 Ma Creek Synclines along the southern margin of the
Hamersley Basin. The depositional age of the(Nelson, 1999 ) for subvolcanic and granitic rocks
of the Gregory Granitic Complex, located along Turee Creek Group is poorly constrained.
Diamictite of the Meteorite Bore Member of thethe eastern margin of the Pilbara Craton,
CO, Cooglegong Monzogranite; MC, Millindinna Complex; DWC, De Grey and Whim Creek groups and Cleaverville Formation;
WG, Whundo Group. (B) Kaapvaal Craton — Girqualand West basin: KOE, Koegas Subgroup; AH, Asbesheuwels Subgroup; CR,
Campbellrand Subgroup; SD, Schmidtsdrif Subgroup ( Vryburg, Boomplaas and Lokammona Formations). Transvaal basin: PR,
Pretoria Group; PG, Penge Iron Formation; OF, Oak Tree Formation; BF, Black Reef Formation. Witwatersrand triad: PN, Pniel
Group; PL, Platberg Group; KV, Klipriviersberg Group; G&D, Gaborone Complex and Derdepoort Belt basaltic sequence; U,
Usushawana Intrusive Complex; CRa, Central Rand Group; WR, West Rand Group; PSG, Pongola Supergroup; Dom, Dominion
Group.

178 D.R. Nelson et al. /Precambrian Research 97 ( 1999) 165–189
Turee Creek Group contains rhyolite clasts that Steynsdorp Pluton, situated in the south-eastern
part of the Barberton belt. This date is withinwere interpreted to have been derived from the
underlying Woongarra Volcanics of the Hamersley error of the date of 3504±6 Ma obtained by
Compston and Kro
¨ner (1988) for a component inGroup (Trendall, 1976). Deposition of the
Meteorite Bore Member must therefore have post- a tonalitic gneiss of the Ancient Gneiss Complex.
A trondhjemitic phase of the Theespruit Plutondated emplacement of the rhyolite at 2449±3Ma
(Barley et al., 1997). A minimum time for depos- from the southern part of the Barberton region
was dated at 3443+4/−3 Ma by Kamo and Davisition of the Turee Creek Group is provided by the
date of 2209±15 Ma reported for the Cheela (1994), in agreement with the result of 3437±6Ma
obtained earlier by Armstrong et al. (1990). KamoSprings Basalt of the overlying Wyloo Group
(Martin et al., 1999). and Davis ( 1994 ) defined further magmatic epi-
sodes at 3470 to 3440 Ma, 3230 to 3200 Ma and
at ca 3110 Ma. The ca 3250 to 3190 Ma granite
intrusion event in the Barberton region was earlier
3. Kaapvaal Craton
suggested by the imprecise 3250±30 Ma date
obtained for the Stentor Tonalitic Pluton
The regional geology of the Kaapvaal Craton
(Tegtmeyer and Kro
¨ner, 1987), the 3226±14 Ma
of southern Africa and locations of U–Pb zircon
date obtained for a tonalite phase from the Kaap
geochronology sampling sites throughout the
Valley Pluton (Armstrong et al., 1990 ) and an
craton are shown in Fig. 2. The Archaean rocks
imprecise 3180±75 Ma date obtained for the
of the Kaapvaal Craton are poorly exposed, by
Nelshoogte Pluton (Barton et al., 1983 ). A ca
comparison with the Pilbara Craton. The quantity
3110 Ma magmatic event is also supported by the
of U–Pb zircon data available (summarised in
date of 3120±5 Ma determined by Armstrong
Table 1) is also substantially less than for the
et al. (1991) for a granitic rock from southwest of
Pilbara Craton, although it is still possible to make
Klerksdorp. Layer et al. (1989) determined a date
some inferences from those that are available.
of 2687±6 Ma for the Mbabane Pluton, and con-
sidered this to represent the last major Archaean
3.1. Chronology of granite–greenstone crust
intrusive event in the Kaapvaal Craton.
formation in the Kaapvaal Craton
Dates for volcanic and sedimentary units within
the oldest Onverwacht Group of the Barberton
The chronology of (mainly magmatic) events
Greenstone Belt range from ca 3548 Ma, deter-
within the granite–greenstone component of the
mined by Kro
¨ner et al. (1996) for a schistose
Kaapvaal Craton, based on available U–Pb zircon
tuffaceous unit from the Theespruit Formation, to
data, is summarised in Fig. 3.
ca 3300 Ma, determined by Byerly et al. (1996)
The Barberton Greenstone Belt of the eastern
for felsic tuffaceous units from the Mendon
Transvaal region consists of ultramafic to felsic
Formation near the top of the Upper Onverwacht
volcanic and sedimentary rocks at generally low
Group. The Fig Tree Group was deposited uncon-
metamorphic grade. These are in contact with a
formably on the Upper Onverwacht Group
range of trondhjemitic, tonalitic and granodioritic
between 3260 and 3225 Ma (Byerly et al. 1996 ).
plutons. The oldest date from the Kaapvaal Craton
The depositional age of the overlying Moodies
was obtained for a gneissic tonalite from the
Group is not well constrained. Armstrong et al.
Ancient Gneiss Complex, a high-grade gneiss ter-
(1990) presented evidence suggesting that the
rane in fault contact with the south-eastern margin
Moodies Group may be as young as 3164 Ma.
of the Barberton Greenstone Belt, for which an
Kro
¨ner and Compston (1988) dated granite peb-
igneous crystallization age of 3644±4 Ma was
bles within the Moodies conglomerate at ca 3570,
inferred by Compston and Kro
¨ner (1988). Kamo
3531 and 3518 Ma.
and Davis (1994 ) obtained precise U–Pb zircon
Within the Murchison belt further to the north
dates for 23 granitic, subvolcanic and felsic vol-
of Barberton, three main magmatic events at cacanic samples from the Barberton region. A date
of 3509+8/−7 Ma was obtained for the 2970, 2820 and 2680 Ma were documented by

179D.R. Nelson et al. /Precambrian Research 97 ( 1999) 165–189
Poujol et al. (1997 ), suggesting that this terrane (Robb et al., 1990). These considerations constrain
may have developed over a shorter time than the the likely time of onset of widespread erosion of
Barberton belt. the Kaapvaal granite–greenstone crust and com-
Apart from the Barberton, Murchison, mencement of deposition of the overlying
Sutherland and Pietersburg granite–greenstone Witwatersrand triad sediments to the interval 3125
belts of the eastern part of the Kaapvaal Craton, to 3068 Ma.
much of the craton is concealed beneath extensive The volcanic and clastic sedimentary rocks of
sedimentary cover. However, the Kraaipan gran- the Pongola Supergroup overlie the south-eastern
ite–greenstone belt of the western margin of the part of the Kaapvaal Craton. A rhyolite from the
Kaapvaal Craton is in part exposed in the Pongola Supergroup has been dated at
Mafikeng–Vryburg region. Robb et al. (1992 ) 2985±1 Ma (Hegner et al., 1994). Hegner et al.
reported a date of 3031+11/−10 Ma for granitic ( 1984) reported a date of 2871±30 Ma for gab-
rocks from ca 90 km southeast of Mafikeng. broic rocks from the Usushawana intrusive suite,
Anhaeusser and Walraven (1997) also obtained which have intruded the Pongola Supergroup.
zircon Pb-evaporation dates of 2846±22 Ma for Granitic and granophyric rocks of the
the Kraaipan granodiorite and 2749±3 Ma for Gaborone Granitic Complex were dated at
the Mosita adamellite. 2783±2 Ma (Grobler and Walraven, 1983; Moore
et al., 1993), and a similar date of 2782±2Ma
3.2. Supracrustal sequences of the Kaapvaal Craton was also reported for the Plantation Porphyry
( Walraven et al., 1996) that overlies the Kanye
The chronostratigraphy of the supracrustal volcanics and Gaborone Granite. Although
sequences of the Kaapvaal Craton is summarised Walraven et al. (1994 ) documented a Pb-
in Fig. 4. The granite–greenstone basement of the evaporation 207Pb/206Pb date of 2769±2 Ma for a
Kaapvaal Craton was subject to extensive erosion basalt from the Derdepoort basaltic sequence, an
prior to and during deposition of the sedimentary older date of 2782±5 Ma was obtained by
and volcanic rocks of the Dominion Group and Wingate ( 1997 ) for a felsic volcanic rock from a
Witwatersrand and Ventersdorp Supergroups; sequence overlying the Derdepoort basalts and the
these three major units are informally known as best estimate of the Derdepoort Basalt sequence is
the Witwatersrand triad. Uplift and the onset of therefore taken to be ca 2782 Ma. The Gaborone
widespread erosion probably occurred later than Granitic Complex, Plantation Porphyry, Kanye
3120±5 Ma ( Armstrong et al., 1991 ), the youngest volcanics and Derdepoort basalts were therefore
emplacement age so far determined for a granite emplaced contemporaneously at ca 2782 Ma.
that is unconformably overlain by supracrustal The predominantly basaltic rocks of the
rocks of the triad. A study of detrital zircons in Ventersdorp Supergroup overlie the Dominion
Dominion Group sediments by Robb et al. ( 1990 ) Group and Witwatersrand Supergroup, and attain
indicated that parts of the Dominion Group were a maximum thickness of almost 8 km. Armstrong
deposited later than 3105±3 Ma, whereas a date et al. (1991) determined a date for the
of 3074±6 Ma obtained for a quartz–feldspar Klipriviersberg Group near the base, and thus for
porphyry within the Dominion Group (Armstrong the onset of deposition, of the Ventersdorp
et al., 1991) indicates that deposition of at least Supergroup, of 2714±16 Ma and a date for the
part of the Dominion Group pre-dates this time.
overlying Makwassie Formation porphyry of
Detrital zircons in sediments of the overlying West
2709±8 Ma. These are within error of the date of
Rand Group indicate that these sediments were
2714±3 Ma determined by Walraven et al. ( 1991 )
deposited later than 3060±2 Ma, in broad
for the Kareefontein Quartz Porphyry from the
agreement with the conclusions drawn by Barton
south-western Kaapvaal.
et al. (1989) in a similar study of detrital zircons
The Ventersdorp Supergroup is unconformably
within the Orange Grove Quartzite Formation.
overlain by shales, carbonates, banded-iron forma-
The Turffontein Subgroup of the Central Rand
Group was deposited later than 2909±3 Ma tions and minor volcanic rocks of the Transvaal

180 D.R. Nelson et al. /Precambrian Research 97 ( 1999) 165–189
Supergroup. The Transvaal Supergroup occurs shales and banded iron-formation of the Kuruman
and Griquatown Formations of the Asbesheuwels
within two main depositional basins — the
Subgroup. A date of 2432±31 Ma (cited in
Transvaal basin in the Transvaal region and the
Trendall et al., 1990) has been documented for a
Griqualand West basin in the Northern Cape
sample taken from near the boundary between the
region. The Griqualand West basin may also be
Kuruman and Griquatown banded iron-form-
subdivided into the Prieska and Ghaap Plateau
ation sequences. In addition, dates of 2489±
sub-basins that have different sedimentological his-
33 Ma (A.F. Trendall, unpublished data) and
tories (Altermann and Nelson, 1998).
2465±7 Ma [R. A. Armstrong, personal com-
The Vryburg Formation of the Ghaap Group
munication, cited in Martin et al. (1998)] have
is the lowest stratigraphic unit above the unconfor-
been obtained for samples taken near the base of
mity over the Ventersdorp Supergroup lavas in the the Griquatown and top of the Kuruman forma-
Griqualand West basin. The formation consists of tions respectively. In the Transvaal basin, a date
shales, quartzites, siltstones and volcanic rocks. A of 2480±6 Ma has been obtained for a sample
lava from the Vryburg Formation was dated by from the Penge Iron Formation (Chuniespoort
Walraven et al. (1999) at 2642±3 Ma. Subgroup; A.F. Trendall, unpublished data).
Altermann and Nelson (1998) dated tuffbeds A date of 2222±13 Ma was reported by Cornell
in carbonate-facies units of the Campbellrand et al. (1996) for the Ongeluk Basaltic Andesite
Subgroup of the Griqualand West basin. Dates of Formation of the Griqualand West basin, which is
2588±6 Ma and 2549±7 Ma were obtained for stratigraphically equivalent to the Hekpoort Basalt
the middle and the upper parts of the Nauga of the Transvaal basin. Sandstones, shales and
Formation at Prieska, respectively. The latter result subordinate lavas and carbonates of the upper
is consistent with the date of 2552±11 Ma earlier Pretoria Group were deposited onto the Hekpoort
reported by Barton et al. (1994) for a tuffclose to Basalt in the Transvaal basin prior to ca 2050 Ma,
the top of the Nauga Formation. Altermann and when the Bushveld layered intrusive complex was
Nelson (1998) also reported dates of 2555±19 Ma emplaced ( Eriksson et al., 1995 ). The banded iron-
for the upper Monteville Formation and formation and dolomitic rocks of the upper
2516±4 Ma for the upper Gamohaan Formation. Postmasburg Group in the Griqualand West basin
A date of 2521±3 Ma was also obtained for a tuffare stratigraphically equivalent to the siliciclastic
band in the upper part of the Gamohaan rocks above the Hekpoort lava in the upper
Formation by Sumner and Bowring (1996). Pretoria Group of the Transvaal basin. These are
Altermann and Nelson (1998) presented evidence unconformably overlain by the Olifantshoek
indicating that the carbonates of the southwestern Sequence, which contains >1000 m thickness of
part of the Griqualand West basin were signifi- volcanic rocks and sediments of the Mapedi,
cantly older than those of the Gamohaan Lucknow and Hartley Formations. The Hartley
Formation in the Ghaap Plateau region of this Basalt Formation, recently dated at 1928 Ma
basin, but were in part correlatives of the Oak (Cornell et al., 1998), is covered by >3km of
Tree Formation of the Transvaal basin and of quartzites and greywackes. These were deformed
parts of the Monteville Formation on the Ghaap by the ca 1850 to 1750 Ma Kheis–Koranna
Plateau. Dates of 2550±3 Ma and ca 2585 Ma Orogeny along the western margin of the Kaapvaal
were determined by Walraven and Martini (1995 ) Craton (Cornell, 1987; Altermann and Halbich,
and Martin et al. (1998), respectively for the Oak 1991 ).
Tree Formation of the Transvaal basin. It is,
however, unclear why such different dates were
obtained for the same sample from the Oak Tree 4. Comparative chronology of geological events in
Formation examined in the studies of Walraven the Pilbara and Kaapvaal cratons
and Martini (1995 ) and Martin et al. ( 1998).
The carbonates of the Campbellrand Subgroup Geological comparisons of the Pilbara and
Kaapvaal cratons have in the past focused onare overlain in the Griqualand West basin by

181D.R. Nelson et al. /Precambrian Research 97 ( 1999) 165–189
comparatively few key aspects, such as general of the Pilbara Craton, which was accompanied by
the onset of eruption of the flood basalts of thestratigraphic and geochronological similarities
between the flood basalt sequences of the Fortescue Group and the widespread emplacement
of granitic rocks into the Pilbara granite–green-Ventersdorp and Fortescue volcanics, and of the
Hamersley and Transvaal carbonate and banded stone basement, has not been identified on the
Kaapvaal Craton.iron-formation sequences. Implicit in many of
these studies is the assumption that the Pilbara
and Kaapvaal cratons were united prior to depos- 4.2. Timing of the widespread erosion marking the
transition from granite–greenstone crust-formationition of these supracrustal sequences. Both cratons
should therefore have identical geological histories to deposition of supracrustal sequences on the
Pilbara and Kaapvaal cratonsprior to ca 2700 Ma. Available geochronology
data, summarised in Table 1, for the Pilbara and
Kaapvaal cratons, particularly supplemented by The available evidence suggests that the onset
of widespread erosion of the Kaapvaal granite–new data from the Pilbara Craton, enables a
detailed assessment of these general comparisons. greenstone crust and commencement of deposition
of the overlying clastic sediments of the
Witwatersrand triad occurred within the interval4.1. Magmatic episodes within the Pilbara and
Kaapvaal granite–greenstone terranes 3125 to 3068 Ma. Granite–greenstone crust was
still forming in the west Pilbara during this interval,
with emplacement of the 3125 to 3112 Ma ShollWithin the Pilbara Craton, major magmatic
events have been identified at ca 3470 to 3400, greenstone belt of the Whundo Group and associ-
ated contemporaneous granitic rocks. There is no3325 to 3290, 3270 to 3235, 3140 to 3090, 3025 to
2990, 2950 to 2910 and 2760 Ma. All are charac- evidence of widespread erosion of the western part
of the Pilbara Craton prior to ca 3110 Ma,terized by well-defined periods of ∏10–70 Ma
duration, of generally widespread magmatic activ- although it is possible that erosion of the eastern
part of the Pilbara Craton may date from thisity. Despite the comparatively poorer data cover-
age, a relatively well-defined and apparently time. Widespread deposition of the ca 3030 to
2950 Ma Mallina Formation and its equivalentscontinuous episode of magmatic activity may be
identified within the granite–greenstones of the provide the earliest evidence of craton-wide denu-
dation of the granite–greenstone basement of theKaapvaal Craton from 3580 to 3430 Ma, with an
additional abrupt and well-defined event at Pilbara Craton. The available geochronology data
suggests that these were deposited ca 30 Ma later2782 Ma. Poorly-defined episodes at 3250 to 3220,
3120 to 3100 and ca 2985 Ma may also be present than the equivalent sediments, at the base of the
Witwatersrand triad, of the Kaapvaal Craton.within the Kaapvaal Craton. Although there is
evidence suggesting that increased magmatic activ- Dominion Group sediments were deposited on the
Kaapvaal Craton between ca 3105 and 3074 Ma,ity within the Kaapvaal Craton may have occurred
simultaneously with that in the Pilbara Craton (for with the overlying West Rand Group sediments
deposited later than 3060 Ma and the Centralexample, at ca 3250 and 3110 Ma), the overall
chronological patterns of granite–greenstone crust Rand Group later than 2909 Ma. Deposition of
the clastic sedimentary sequences of the Mallinagrowth evident for the two cratons are not similar
(see Fig. 3). This difference becomes more appar- and Cattle Well Formations of the Pilbara Craton
therefore probably coincided with that of parts ofent when a comparison of widespread short-lived
events on both cratons is made. Equivalents of the West Rand Group.
In summary, the available geochronological evi-the 2985 Ma volcanic rocks of the Pongola
Supergroup, and of the 2782 Ma ‘Gaborone– dence suggests that the onset of craton-wide ero-
sion of the granite–greenstone basement andKanye–Plantation Porphyry–Derdepoort’ events,
have not been recognised on the Pilbara Craton, deposition of supracrustal rocks occurred prior to
ca 3070 Ma on the Kaapvaal Craton but later thanwhereas the well-defined and abrupt 2760 Ma event

182 D.R. Nelson et al. /Precambrian Research 97 ( 1999) 165–189
ca 3030 Ma on the Pilbara Craton. However, as 4.4. Shale, carbonate and banded iron-formation
facies deposition within, and stratigraphic
the onset of deposition of sedimentary rocks of the
correlation between, the supracrustal sequences of
De Grey Group of the Pilbara Craton is not well
the Pilbara and Kaapvaal cratons
constrained and older De Grey Group sediments
may exist but have not yet been identified, it is
Detailed stratigraphic and geochronological
possible that the onset of the craton-wide erosion
investigations by Altermann and Nelson ( 1998)
of the granite–greenstone basement on the Pilbara
have demonstrated that major lithofacies changes
and Kaapvaal cratons occurred synchronously at
occurred diachronously across the depositional
some time within the interval 3125 and 3068 Ma.
sub-basins of the Transvaal Supergoup. For exam-
ple, the change from deposition of carbonates to
shales in the upper part of the Campbellrand
4.3. Onset, duration and chemical characteristics of Subgroup apparently occurred significantly earlier
major flood basaltic magmatism episodes on the within the Prieska sub-basin than in the Ghaap
Pilbara and Kaapvaal cratons Plateau sub-basin. Detailed investigative work on
this aspect of Hamersley Basin deposition has yet
Emplacement of the ca 2782 Ma Gaborone to be undertaken. Nevertheless, it is clear from
Granitic Complex, Plantation Porphyry and Fig. 4 that, although there are some general sim-
Derdepoort basalts within the Kaapvaal Craton ilarities in the nature of the lithologies represented,
occurred ca 20 Ma prior to the onset of eruption there are also significant chronostratigraphic
of the Fortescue Group lavas, which coincided differences between the Hamersley and Transvaal
with an abrupt and widespread magmatic event at basins. That such differences might be explained
2760 Ma throughout the Pilbara Craton. No equiv- by diachronous deposition of the various litholo-
alents of these 2760 Ma magmatic products have gies represented within a single Hamersley–
been documented from the Kaapvaal Craton. The Transvaal depositional basin is considered highly
onset of eruption of the basaltic lavas of the unlikely.
Ventersdorp Supergroup at 2714±3 Ma occurred Some important differences in the stratigraphies
>40 Ma later than that of the Fortescue Group. of supracrustal sequences of the Pilbara and
Although the onset of flood basaltic magmatism Kaapvaal cratons can be seen in Fig. 4. The Pilbara
was diachronous on the Pilbara and Kaapvaal Craton lacks sequences comparable to the
cratons, a flood basalt eruption episode took place Dominion and Pongola Groups, and volcanic
contemporaneously at ca 2714 Ma on both cra- equivalents of the lower parts of the Fortescue
tons, with the eruption of the basal Ventersdorp Group are not present in the Kaapvaal Craton.
lavas occurring simultaneously with that of the Furthermore, the clastic sedimentary and volcanic
Maddina Formation of the Fortescue Group. rocks of the Vryburg Formation in the Griqualand
Nelson et al. ( 1992) investigated the geochemi- West basin were deposited unconformably on vol-
cal, Sm–Nd isotopic and metamorphic histories of canic rocks of the Ventersdorp Supergroup at ca
the Fortescue Group and Ventersdorp Supergroup 2642 Ma. The unconformable nature of the bound-
igneous rocks. Both sequences were shown to have ary between these sequences [ VIII and TI of
mixed tholeiitic and calc-alkaline affinities and Cheney ( 1996)] in the Transvaal basin is well
immobile-element correlations indicating deriva- established and may be observed at the base of
tion from chemically heterogeneous, incompatible- the Transvaal Supergroup wherever it is exposed
element-enriched sources. Similar negative eNd (Altermann and Halbich, 1991; Eriksson et al.,
values, of between −1.5 and −4.4 for the 1995). No corresponding sequence stratigraphic
Fortescue Group and 0 and −3.4 for the boundary in the Hamersley Basin has been recog-
Ventersdorp Supergroup, were interpreted as indi- nised. A conformable sequence of shales and vol-
cating a common mode of origin involving the caniclastic rocks of the 2690 to 2630 Ma Jeerinah
interaction of asthenospheric and subcontinental Formation were deposited on the Pilbara Craton
during development of the unconformable bound-lithospheric mantle sources.

183D.R. Nelson et al. /Precambrian Research 97 ( 1999) 165–189
ary between the Vryburg Formation and Gamohaan Formations in the Griqualand West
Ventersdorp Supergroup in the Griqualand West basin.
basin at ca 2642 Ma. The boundary between the Four second-order transgression-regression
Jeerinah and Marra Mamba Iron Formations is cycles were delineated in the Prieska, Ghaap
conformable in the main basin area (Davy and Plateau and Transvaal sub-basins of the Transvaal
Hickman, 1988), although the absence of the Supergroup by Altermann and Nelson ( 1998 ).
Marra Mamba Iron Formation in the extreme These second-order cycles, of ca 10–50 Ma dura-
northeastern part of the basin could imply some tion, were interpreted to reflect bathymetric fluc-
discordance. tuations during a period of continuous (first-order)
Deposition of banded iron-formation facies transgression (deepening), based on the observed
within the Hamersley Basin began with the Marra change of sedimentation from marginal marine
Mamba Iron Formation at ca 2630 Ma and contin- siliciclastics to platformal carbonates, followed by
ued until ca 2597 Ma. On the Kaapvaal Craton shales and finally to banded iron-formations. In
during this time interval, carbonates and shales of the Griqualand West basin, the deposition of the
the Boomplaas and Lokammona Formations, and Vryburg Formation was interpreted to mark the
carbonates of the lower Nauga Formation, were onset of transgression. This was followed by a
deposited in the Griqualand West basin. shallowing-upward cycle, during which the
Deposition of the carbonates of the Wittenoom Boomplaas carbonate platform sediments were
Formation in the Hamersley Basin, and of the deposited. The second transgressive step is marked
Campbellrand and Malmani Subgroups within the by the Lokammona shales, and the subsequent
Griqualand West and Transvaal basins, coincided shallowing-upward cycle by the lower Nauga
from about 2600 Ma until ca 2530 or 2520 Ma. Formation. These two lower cycles cannot be
The transition from the Campbellrand and confidently identified within the Transvaal basin,
Malmani carbonates to the banded iron-forma- due to inadequate age constraints and poor rock
tions of the Kuruman and Griquatown Formations preservation. The upper Nauga, Monteville and
on the Kaapvaal Craton occurred at or shortly Oak Tree Formations mark a third transgressive
before ca 2500 Ma, whereas within the Hamersley phase, followed by a long-term shallowing-upward
Basin, the Wittenoom carbonates gave way to cycle and the development of a stromatolitic
shales and minor banded iron-formations of the carbonate platform with deposition of the
Mount Sylvia Formation at this time, with depos- Campbellrand and Malmani Subgroups in the
ition of the banded iron-formations of the Ghaap Plateau sub-basin and in the Transvaal
Brockman Iron Formation commencing at ca basin. In the Prieska sub-basin of the Griqualand
2480 Ma, some 20 Ma later than on the Kaapvaal West basin, however, shales of the Naute Member
Craton. Simonson et al. (1993) interpreted the were deposited during this time. The fourth trans-
carbonates of the Wittenoom Formation as shelf gression is perceptible from the development of a
deposits of partly turbiditic origin, laid down in pelagic basin succeeding the drowning of the car-
considerable water depths, below fair-weather bonate platform, with deposition of the banded
wave base, and it is difficult to interpret the change iron-formation of the Kuruman and Penge
from carbonate to shale or banded iron-formation
Formations. The banded iron-formation of the
sedimentation in the Hamersley Basin as a result
Griquatown Formation and the overlying siliciclas-
of increasing bathymetry only. The depositional
tic rocks of the Koegas Subgroup mark the fourth
environment of the Wittenoom Formation dolo-
regressive cycle.
mites was therefore quite different to that of the
Second-order transgression–regression cycles
stromatolitic, platformal dolomites of the
may also be recognised in the Hamersley Basin.
Campbellrand or Malmani Subgroups of the
Detailed correlation of these cycles across the
Transvaal Supergroup. These depositional differ-
Hamersley and Transvaal basins is hampered by
ences become less apparent, however, with the
inadequate geochronology coverage, but there are
drowning of the carbonate platforms during depos-
ition of the upper parts of the Nauga and significant similarities, and differences, in the facies

184 D.R. Nelson et al. /Precambrian Research 97 ( 1999) 165–189
development on the two cratons. Within the Halbich, 1991), whereas the Pretoria Group
includes at least one major unconformity belowHamersley Basin, the onset of deposition of the
Marra Mamba banded iron-formation at ca the Hekpoort lava ( Eriksson et al., 1995). The
Pretoria Group was intruded by the 2054 Ma2630 Ma may mark a transgression, with the
change to carbonate deposition at ca 2597 Ma Bushveld Igneous Complex, of which no equivalent
exists on the Pilbara Craton. Although thecorresponding to a partial regression. The trans-
gression at 2630 Ma could possibly correlate with Makganyene and Boshoek glacial deposits of the
Kaapvaal Craton may be correlated with thethe transgression above the Boomplaas carbonates
of Griqualand West, whereas the subsequent Meteorite Bore Member of the Hamersley Basin,
glacial deposits of this age are widespread on otherregression may be correlated with that above the
Lokammona Formation. Both regression cycles continents [ i.e. Kenorland; see Aspler and
Chiarenzelli (1998)] , and may reflect global cli-resulted in carbonate sedimentation, although as
mentioned earlier, the carbonates of the Monteville matic conditions.
As far as the available dating allows, the aboveand Nauga Formations reflect different (stromato-
litic) conditions compared with the (deep-water) analysis has, in general terms, confirmed the broad
proposal of Cheney (1996) that some events pre-Wittenoom carbonates. The Nauga Formation
peritidal carbonates were drowned at ca 2549 Ma served within the supracrustal record of the Pilbara
and Kaapvaal cratons may be correlated in time.and replaced by shale sedimentation. At about the
same time on the Pilbara Craton, the Wittenoom Major transgressions within the Hamersley Basin
may be correlated with those in the Prieska sub-Formation carbonates were replaced by banded
iron-formation of the Mount Sylvia Formation, basin, and with those in the Ghaap Plateau and
Transvaal transgressions but with less confidence.here interpreted as a second transgression over the
Hamersley Basin. The third transgression of the Banded iron-formation sedimentation gave way to
deposition of coarse clastic sediments of the TureeHamersley Basin resulted in the deposition of
banded iron-formation of the Dales Gorge Creek Group on the Pilbara Craton at some time
within the interval 2449 to 2209 Ma, whereas theMember above the Mount McRae Shale, at ca
2480 Ma. This occurred ca 20 Ma later than the corresponding clastic sediments of the Pretoria
and Postmasburg Groups on the Kaapvaal Cratonmajor transgression that resulted in craton-wide
banded iron-formation deposition on the were deposited onto banded iron-formation of the
Griqualand West and Transvaal basins between caKaapvaal craton. The Joffre Member banded iron-
formation may mark a fourth transgression of the 2460 and 2222 Ma. However, transgression–regres-
sion cycles are generally considered to reflect theHamersley Basin, provided that the Whaleback
Shale reflects a regressive step. Evidence of regres- combined effects of global fluctuations in sea level
with changes in continental freeboard. Fluc-sion between 2470 and 2449 Ma has not been
recognised on the Kaapvaal Craton. tuations in global sea level may result in the
deposition of similar sedimentary facies simulta-On the Kaapvaal Craton, the Koegas Subgroup,
which consist mainly of quartzites and shales with neously on widely-dispersed cratons, and does not
require that cratons with similar histories of trans-thin banded iron-formation and carbonate units,
conformably overlies the Griquatown Banded Iron gression and regression were contiguous. The sim-
ilarities in the first- and second-order trans-Formation in the Griqualand West basin. In the
Transvaal basin, the Penge Banded Iron Formation gression-regression cycles of the supracrustal
sequences of the Pilbara and Kaapvaal cratons areis unconformably overlain by quartzites and grey-
wackes of the Duitschland Formation. These here interpreted as resulting from global sea-level
fluctuations, with the differences considered to beclastic sediments may have been deposited
synchronously with parts of the Turee Creek due to differences in the subsidence rates of the
two cratons during accumulation of the thick pilesGroup of the Pilbara Craton. The Postmasburg
Group includes at least two major unconformities, of supracrustal volcanic and sedimentary rocks. A
simple correlation of transgression–regressionone below the Makganyene diamictite and the
other below the Ongeluk lava (Altermann and cycles on the Pilbara and Kaapvaal cratons cannot

185D.R. Nelson et al. /Precambrian Research 97 ( 1999) 165–189
therefore contribute directly to the question of the of the Pilbara granite–greenstone basement. In the
case of the Pilbara Craton, however, the regionalexistence of ‘Vaalbara’.
differences are primarily related to the apparent
absence of any rocks older than c. 3275 Ma in the
western part of the craton– there is clear evidence5. Comparison of the Archaean to Early
Proterozoic geological histories of the Pilbara and of shared magmatic events younger than c.
3275 Ma within both the eastern and western partsKaapvaal cratons — summary and implications
of the Pilbara granite–greenstone basement. While
there is evidence of magmatic events at c. 3250From the above comparisons, it is clear that
there are some general similarities in the geological and 3110 Ma on both cratons, comparison of the
chronologies of magmatic events within the Pilbarafeatures of both cratons:
1. The overall duration of formation (i.e. from ca and Kaapvaal cratons provides no compelling
evidence of shared geological development at any3650 to 3100 Ma), general ‘granitoid dome and
arcuate greenstone’ geometries, structural char- time during formation of the granite–greenstone
basements of both cratons.acteristics, chemistries and isotopic characteris-
tics of the granitic and volcanic rocks of the 2. The craton-wide erosion events and the gradual
transition from granite–greenstone-style crustgranite–greenstone crusts, are generally similar.
The early development of the granite–green- formation to supracrustal clastic sedimentation
occurred within the time interval 3125 tostone crusts of both cratons was characterized
by a continuous and long-lived episode of mag- 3030 Ma on both cratons. Based on the avail-
able geochronological evidence, it is possiblematism, between ca 3470 and 3400 Ma in the
case of the Pilbara Craton, and ca 3540 to that the onset of craton-wide erosion of the
granite–greenstone basement and widespread3430 Ma in the case of the Kaapvaal Craton
(see Fig. 2). Granite–greenstone crust forma- deposition of clastic sediments occurred
synchronously at some time within this timetion within both cratons was episodic, with
major episodes of ca 10–100 Ma duration interval on both cratons. However, such syn-
chronisity, if demonstrated by future work, mayresulting in contemporaneous greenstone volca-
nism on, and granitic intrusion into, pre-existing be attributable to global sea-level fluctuations
and does not provide evidence that these cratonsgranite–greenstone crust, separated by periods
of magmatic quiescence and (presently poorly- were once contiguous.
3. Thick sequences of flood basalts were depositeddefined ) deposition of clastic and chemical sedi-
ments. These similarities provide strong evi- on both cratons during the time interval 2760
to 2640 Ma. The onset of deposition of flooddence for the early formation of these cratons
by the operation of common processes that basaltic volcanism on both cratons was appa-
rently diachronous, with eruption of Fortescuewere in some respects dissimilar to those typical
of Phanerozoic orogenic belts. However, there Group volcanic rocks on the Pilbara Craton
having commenced at least 30 Ma prior to thatare important differences in the chronologies of
major granite–greenstone crust-forming events of the Ventersdorp Supergroup on the Kaapvaal
Craton. Evidence for large-scale flood basalticin the Pilbara and Kaapvaal basements, with a
high degree of disparity in the timing of major eruptions at ca 2715 Ma are preserved on both
cratons. However, a large proportion of thegranite–greenstone crust-forming events on
both cratons ( Fig. 3 ). granite–greenstone crusts of both the Yilgarn
Craton of Western Australia, and of theIt might be argued that the differences in the
chronologies of magmatic events within the gran- Superior Craton in the north-eastern part of
the North American continent, also formedite–greenstone crusts of the Pilbara and Kaapvaal
cratons reflect regional differences in the Vaalbara during the time interval 2760 to 2640 Ma. Based
largely on a comparison of the timing of geolo-granite–greenstone basement, such as that which
clearly exists between the eastern and western parts gical events within the Yilgarn and Superior

186 D.R. Nelson et al. /Precambrian Research 97 ( 1999) 165–189
cratons, Nelson (1998a) presented arguments ral similarities described above suggest that there
advocating the operation of global-scale mag- may have been major eras of the Archaean history
matic eruption events at 2715 and 2705 Ma. of the Earth, of ca 60–200 Ma duration, during
This mechanism does not require the Pilbara, which the styles and intensity of large-scale volca-
Kaapvaal, Yilgarn or Superior cratons to have nism, subaerial erosion, magnitude of sea-level
been contiguous in order to account for the fluctuations and deposition of chemical sediments,
presence of synchronous magmatism within were different. These differences may have been
each. linked to irreversible global climatic, mantle con-
4. The onset of major carbonate and banded iron- vection and/or mantle-crust development phases
formation deposition within the Hamersley and of the early Earth.
Transvaal basins occurred diachronously on In addition to the Pilbara and Kaapvaal cra-
both cratons, but within the general time tons, thick sequences of volcanic rocks were also
interval ca 2630 to 2430 Ma. Major transgres- erupted onto the Amazon, Sa
˜o Francisco and
sions within the Hamersley Basin may be corre- Karnataka cratons during the interval ca 2760 to
lated with those in the Prieska sub-basin and, 2680 Ma. Substantial parts of both the Superior
with less confidence, to those in Ghaap Plateau and Yilgarn cratons were also formed during this
and Transvaal sub-basins. Banded iron-forma- time. Nelson (1998a) presented evidence of abrupt
tion sedimentation gave way to the deposition and synchronous episodes of ultramafic magma-
of coarse clastic sediments of the Turee Creek tism in the granite–greenstone terranes of the
Group on the Pilbara Craton between ca 2450 Superior and Yilgarn cratons during this period,
and 2200 Ma. In the Griqualand West basin of and argued that these were a consequence of rapid,
the Kaapvaal Craton during this interval, iron- large-scale convective overturn of the Earth’s
formation sedimentation of the Griquatown mantle. This process was envisaged to have been
Iron Formation gave way to carbonate and superimposed on plate tectonic processes. One of
siliciclastic sediments of the Koegas Formation, these events, at ca 2715 Ma, was identified in the
and subsequently to the clastic sediments of the granite–greenstone terranes of the Superior
Postmasburg Group. In the Transvaal basin, Craton, and in the Fortescue and Ventersdorp
the Duitschland Formation was disconformably flood basaltic sequences of the Pilbara and
deposited onto the Penge Iron Formation Kaapvaal cratons respectively.
during this interval. However, similarities in the Recognition of a period of globally more intense
first- and second-order transgression–regression magmatic activity between 2760 and 2680 Ma may
cycles of both cratons may be attributable to have important implications for models of depos-
global sea-level fluctuations and do not provide ition of the major banded iron-formation
evidence that these cratons were once sequences during the Late Archaean and Early
contiguous. Proterozoic. In addition to the Griqualand West
There is, therefore, no compelling evidence, from and Transvaal basins of the Kaapvaal Craton and
comparison of either the timing of magmatic epi- the Hamersley Basin of the Pilbara Craton, thick
sodes or from the chronological correlation of
banded iron-formation sequences were also depos-
lithostratigraphic similarities, to support the
ited onto the Amazon (i.e. Caraja
´s Formation)
hypothesis that the Pilbara and Kaapvaal cratons
and Sa
˜o Francisco cratons (Quadrilatero
formed part of united craton at any time during
Ferrifero), and onto the Karnataka Craton
the period from 3650 to 2200 Ma.
(Dharwar Supergroup) of India, during the Late
Archaean and Early Proterozoic. Banded iron-
formation also occurs within the upper parts of
6. Independent development of the Pilbara and
the greenstone stratigraphies of the Yilgarn and,
Kaapvaal cratons — implications
to a lesser extent, Superior cratons, although these
are generally less extensive than those deposited
If the Pilbara and Kaapvaal cratons evolved
independently during the Archaean, then the gene- on the older, stable cratonic platforms, and are

187D.R. Nelson et al. /Precambrian Research 97 ( 1999) 165–189
analysis and regional correlations of three Neoarchaean and
commonly associated with banded (chemical )
Palaeoproterozoic sub-basins of the Kaapvaal Craton as
chert, turbiditic or coarse clastic sedimentary units.
implied by precise SHRIMP U–Pb zircon ages from volcanic
All of these banded iron-formation sequences over-
sediments. Journal of Sedimentary Geology 120, 225–256.
lie thick sequences of volcanic rocks that were
Anhaeusser, C.R., Walraven, F., 1997. Polyphase crustal evolu-
erupted between ca 2760 and 2680 Ma.
tion of the Archaean Kraaipan granite–greenstone terrane,
Kaapvaal Craton, South Africa. University of the Witwat-
Emplacement of these volcanic sequences will have
ersrand, Economic Geology Research Unit Information Cir-
resulted in slow subsidence of these stable conti-
cular (313 ), 1 –27.
nental platforms. Major fluctuations in global sea
Armstrong, R.A., Compston, W., de Wit, M.J., Williams, I.S.,
levels may also have facilitated the deposition, and
1990. The stratigraphy of the 3.5–3.2 Ga Barberton Green-
preservation, of these Late Archaean to Early
stone Belt revisited: a single zircon ion microprobe study.
Earth and Planetary Science Letters 101, 90–106.
Proterozoic banded-iron sequences. Furthermore,
Armstrong, R.A., Compston, W., Reteif, E., Williams, I.S.,
during the period of more intense mantle overturn
Welke, H.J., 1991. Zircon ion microprobe studies bearing
between 2760 and 2680 Ma, the spreading centres
on the age and evolution of the Witwatersrand Triad. Pre-
within the ocean basins were the main focus of
cambrian Research 53, 243–266.
mafic magmatism. It is proposed here that most
Arndt, N.T., Nelson, D.R., Compston, W., Trendall, A.F.,
Thorne, A.M., 1991. The age of the Fortescue Group, Ham-
of the Fe in the Late Archaean to Early Proterozoic
ersley Basin, Western Australia, from ion microprobe U–Pb
banded-iron sequences may have been derived, by
zircon results. Australian Journal of Earth Sciences 38,
hydrothermal enrichment of seawater in Fe, from
261–281.
extensive ultramafic submarine lava plains that
Aspler, L.B., Chiarenzelli, J.R., 1998. Two Neoarchean super-
were erupted during a period of global upheaval
continents? Evidence from the Paleoproterozoic. Sedi-
between 2760 and 2680 Ma.
mentary Geology 120, 75–104.
Barley, M.E., Pickard, A.L., Sylvester, P.J., 1997. Emplacement
of a large igneous provence as a possible cause of banded
iron formation 2.45 billion years ago. Nature (London)
Acknowledgements
385, 55–58.
Barton, E.S., Robb, L.R., Anhaeusser, C.R., van Nierop, D.A.,
1983. Geochronologic and Sr-isotopic studies of certain
The authors acknowledge the thoughtful and
units in the Barberton granite–greenstone terrain. Geologi-
constructive reviews of Eric S. Cheney
cal Society of South Africa Special Publication 9, 63–72.
(Department of Geological Sciences, University of
Barton, E.S., Compston, W., Williams, I.S., Bristow, J.W.,
Washington, Seattle, USA) and Bruce M.
Hallbauer, D.K., Smith, C.B., 1989. Provenance ages for
the gold-bearing Witwatersrand Supergroup: constraints
Simonson (Department of Geology, Oberlin
from ion microprobe U–Pb ages of detrital grains. Economic
College, Ohio, USA) which improved the manu-
Geology 84, 2012–2019.
script, Arthur H. Hickman and R. Hugh Smithies
Barton, E.S., Altermann, W., Williams, I.S., Smith, C.B., 1994.
(Geological Survey of Western Australia) for
U–Pb age for a tuffin the Campbell Group, Griqualand
countless stimulating discussions about Pilbara
West sequence, South Africa: implications for early Protero-
geology and Professor Pat Eriksson (Department
zoic rock accumulation rates. Geology 22, 343– 346.
Brandl, G., Jaeckel, P., Kro
¨ner, A., 1996. Single zircon age for
of Geology, University of Pretoria, South Africa)
the felsic Rubbervale Formation, Murchison Greenstone
for discussions, support and encouragement. D.R.
Belt, South Africa. South African Journal of Geology 99,
Nelson publishes with the permission of the
229–234.
Director, GSWA.
Buick, R., Thornett, J.R., McNaughton, N.J., Smith, J.B.,
Barley, M.E., Savage, M., 1995. Record of emergent conti-
nental crust ~3.5 billion years ago in the Pilbara craton of
Australia. Nature (London) 375, 574–577.
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