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ORIGINAL RESEARCH
published: 28 May 2020
doi: 10.3389/feart.2020.00158
Frontiers in Earth Science | www.frontiersin.org 1May 2020 | Volume 8 | Article 158
Edited by:
Daniel Nývlt,
Masaryk University, Czechia
Reviewed by:
Cynthia M. Fadem,
Earlham College, United States
Nadia Solovieva,
University College London,
United Kingdom
*Correspondence:
Julien Favreau
jfavreau@ucalgary.ca
Julio Mercader
mercader@shh.mpg.de
Specialty section:
This article was submitted to
Quaternary Science, Geomorphology
and Paleoenvironment,
a section of the journal
Frontiers in Earth Science
Received: 01 October 2019
Accepted: 28 April 2020
Published: 28 May 2020
Citation:
Favreau J, Soto M, Nair R,
Bushozi PM, Clarke S, DeBuhr CL,
Durkin PR, Hubbard SM, Inwood J,
Itambu M, Larter F, Lee P, Marr RA,
Mwambwiga A, Patalano R, Tucker L
and Mercader J (2020) Petrographic
Characterization of Raw Material
Sources at Oldupai Gorge, Tanzania.
Front. Earth Sci. 8:158.
doi: 10.3389/feart.2020.00158
Petrographic Characterization of
Raw Material Sources at Oldupai
Gorge, Tanzania
Julien Favreau 1
*, María Soto 1, Rajeev Nair 2, Pastory M. Bushozi 3, Siobhán Clarke 1,
Christopher L. DeBuhr 2, Paul R. Durkin 4, Stephen M. Hubbard 2, Jamie Inwood 1,
Makarius Itambu 1,3 , Fergus Larter 1, Patrick Lee 5, Robert A. Marr 2, Aloyce Mwambwiga 1,6 ,
Robert Patalano 1, Laura Tucker 1and Julio Mercader 1,7
*
1Department of Anthropology and Archaeology, University of Calgary, Calgary, AB, Canada, 2Department of Geoscience,
University of Calgary, Calgary, AB, Canada, 3Department of Archaeology and Heritage Studies, University of Dar es Salaam,
Dar es Salaam, Tanzania, 4Department of Geological Sciences, University of Manitoba, Winnipeg, MB, Canada,
5Department of Anthropology, University of Toronto, Toronto, ON, Canada, 6National Natural History Museum, Arusha,
Tanzania, 7Department of Archaeology, Max Planck Institute for the Science of Human History, Jena, Germany
Oldupai Gorge is located within the Ngorongoro Conservation Area, a UNESCO World
Heritage Site in northern Tanzania along the western margin of the East African Rift
System. Oldupai’s sedimentary record contains inter-stratified stone tool industries
associated with the Earlier, Middle, and Later Stone Age. While diachronic technological
change is perceptible, the totality of locally available rocks remained largely unchanged
through time. Here, thin section petrography, Scanning Electron Microscopy-Energy
Dispersive X-Ray Spectroscopy, and Electron Probe Micro Analysis were employed to
characterize source lithologies in the Oldupai region. One of our goals was to determine
if outcrops have rock types with unique mineral assemblages amenable for sourcing
lithic artifacts. Petrographic analysis of 62 lithologic samples collected in primary and
secondary positions reveal discriminatory differences. More precisely, five outcrops
have quartzites with unique mineral assemblages, five outcrops have meta-granites
with unique mineral assemblages, Engelosin phonolite samples are texturally and
mineralogically unique, and magmatic samples recovered in secondary position may be
sourced to their volcanic center. Our results demonstrate it is feasible to discriminate
source materials using mineralogy, which implies that sourcing lithic artifacts is possible.
For proof of concept, we assign the source/s of previously described fuchsitic quartzite
artifacts from three archaeological sites at Oldupai to two nearby outcrops. Additional
archaeological testing will allow researchers to glean new understandings of hominin
behavior and stone procurement in the Oldupai paleobasin.
Keywords: petrography, reference collection, raw materials, sourcing, Oldupai Gorge
INTRODUCTION
Rocks used for artifact manufacture are alternatively known as lithic raw materials and
occur as mineral aggregates of igneous, metamorphic, and sedimentary origin that are non-
renewable and spatially exhaustible over a non-geological timeframe (Kyara, 1996). Raw material
characterization and sourcing through comparative study of geological specimens and artifacts
Favreau et al. Raw Material Characterization at Oldupai
(Weigand et al., 1977; Shotton and Hendry, 1979) can provide
insights into stone selection and procurement strategies (Stout
et al., 2005), transportation costs (Kyara, 1999), technological
façonnage (Mason and Aigner, 1987), functional suitability
(Ebright, 1987), anthropogenic usage (Courtenay et al., 2019),
landuse behavior (Tactikos, 2005), population movements
(Reimer, 2018), and social networks of trade and exchange (Lebo
and Johnson, 2007). By extension, inferences may be drawn on
technological, economic, ritual, and political systems in a variety
of archaeological contexts (e.g., Renfrew, 1975; Flannery, 1976;
Sidrys, 1976).
In this study, we characterize a range of lithologies that were
available to hominins at Oldupai Gorge using a combination of
thin section petrography, Scanning Electron Microscopy-Energy
Dispersive X-Ray Spectroscopy (SEM-EDS), and Electron
Probe Micro Analysis (EPMA). One of our goals was to
determine the feasibility of sourcing lithic artifacts based on
their mineralogy (cf. Soto et al., 2020a). Rock samples were
collected in primary and secondary positions from 10 outcrops
within the greater Oldupai region. Sixty-two samples including
quartzites, meta-granites, feldspars, amphibolites, schists,
granofels, phonolites, nephelinites, and basalts were studied
using a polarizing microscope. Ten samples were subsequently
analyzed using SEM-EDS and EPMA to complement
petrographic observations.
We show that several outcrops near Oldupai Gorge have
lithologies that can be identified by a unique combination of
minerals which implies that sourcing lithic artifacts based on
mineralogy is a viable technique. This is evidenced by the
similarity of rock specimens from the Naibor Soit Kubwa and
Naibor Soit Ndogo outcrops to previously described Oldowan
and Acheulean quartzite artifacts from three archaeological sites.
Our results not only establish the merit of further archaeological
testing scaffolded by additional characterization efforts, but also
contribute to the growing body of work which shows that
quartzitic outcrops can be differentiated from each other despite
their assumed homogeneity on a regional scale (Ebright, 1987;
Stross et al., 1988; Pitblado et al., 2008, 2013; Blomme et al.,
2012; Veldeman et al., 2012; Cnudde et al., 2013; Dalpra and
Pitblado, 2016; Soto et al., 2020a,b). Our study will serve as a
referential framework for future researchers to establish new links
between the lithoscape and hominin raw material exploitation at
Oldupai Gorge.
OLDUPAI GORGE, TANZANIA
Geological Setting
Oldupai Gorge is located on the boundary between the Tanzania
Craton to the west and the Mozambique Belt to the east
(Figure 1a). The Tanzania Craton is composed of Archean
(4.0–2.5 Ga) low to medium grade metamorphic and igneous
rocks including greenstones, granite gneisses, and quartzites.
The Neoproterozoic Mozambique Belt comprises more deformed
rocks dominated by quartzites, schists, and granites. Surface
exposures of the Mozambique Belt include the Gol Mountains
in north-central Tanzania (Cahen and Snelling, 1966; Cahen
et al., 1984; Dawson, 2008; Scoon, 2018), and the metamorphic
outcrops to the south near Oldupai Gorge (Figures 1a,b)
(Hay, 1976).
Variably overlying the basement rocks of the Tanzania
Craton and the Mozambique Belt and obscuring their contacts
are volcanic rocks of the Ngorongoro Volcanic Highlands
(NVH) associated with the East African Rift System, which
is an active intra-continental extension zone (Figures 1a,b).
Rifting commenced in the Eocene and resulted in extensive
volcanism that is still active today. Oldupai Gorge is situated
in the North Tanzania Divergence Zone, to the northwest
of the NVH (Figure 1a) and borders the westernmost faults
of the Gregory Rift system (Baker et al., 1972; Dawson,
1992). The NVH is a mostly inactive group of volcanoes
centered around the Ngorongoro Caldera. The catchment of
the Oldupai paleobasin include five volcanic centers of the
NVH: (1) Sadiman (4.63–3.5 Ma; 2,870 m.a.s.l.) (foidite, ijolite,
nephelinite, phonolite, phonolitic tuff, and tephrite) (Hay, 1976;
Mollel and Swisher, 2012; Zaitsev et al., 2012); (2) Engelosin
(3–2.7 Ma; 1,648 m.a.s.l.) (phonolite and phonolitic breccia)
(Hay, 1976; Mollel and Swisher, 2012); (3) Lemagrut (2.4–2.2 Ma;
3,135 m.a.s.l.) (basalt, benmorite, hawaiite, ignimbrite, and
mugearite) (Mollel and Swisher, 2012); (4) Ngorongoro (2.25–
2.01 Ma; 1,700–2,380 m.a.s.l.) (agglomerate, basalt, ignimbrite,
rhyolite, trachyandesite, trachydacite, and trachyte) (Pickering,
1965; Mollel, 2002; McHenry et al., 2008; Mollel et al., 2008;
Mollel and Swisher, 2012); and (5) Olmoti (2.01–1.80 Ma;
3,101 m.a.s.l.) (basalt, ignimbrite, trachyandesite, and trachyte)
(Pickering, 1964, 1965; Hay, 1976; Manega, 1993; Mollel, 2002;
McHenry et al., 2008; Mollel et al., 2009; Mollel and Swisher,
2012) (Figure 1b).
The Main and Side Gorge cut into the basement rocks of
Eastern Serengeti Plains and provide good exposures of the
stratigraphy. During the Early Pleistocene, Oldupai was an
endorheic, rift-shoulder sedimentary basin that hosted a saline
alkaline lake fed by stream networks from the NVH to the west,
and characterized by abruptly rising metamorphic inselbergs
associated with the Mozambique Belt (Hay, 1976; McHenry
et al., 2008). The post-Ngorongoro stratigraphy exposed in
the gorge (Oldupai Group) overlies a basal basalt unit in
the east and an ignimbrite in the west associated with the
final eruption from Ngorongoro (Hay, 1976; McHenry et al.,
2008; Deino, 2012). As volcanic activity subsided, sediments
were delivered to the basin from alluvial fans composed of
pyroclasts to the east and fluvial channels from the west
(Hay, 1976; Ashley and Hay, 2002). Deposition occurred
in a variety of environments, including fluvial channels,
floodplain, and lacustrine settings (Hay, 1976). The Oldupai
Group, which attains a maximum thickness of ∼100 m, is
divided into seven units (Bed I–IV, Masek, Ndutu, and
Naisiusiu) (Hay, 1976; Scoon, 2018) which preserve evidence
of hominin activities. While variations in drainage patterns
and resulting sedimentation altered Oldupai’s paleoecology,
the paleobasin was occupied by a host of hominin species
where they procured raw materials from nearby outcrops to
manufacture stone tools for a variety of daily tasks (Leakey, 1971;
Mora and de la Torre, 2005; Diez-Martín et al., 2009, 2010;
Yravedra et al., 2017).
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Favreau et al. Raw Material Characterization at Oldupai
FIGURE 1 | (a) The East African Rift System superimposed over the Tanzania Craton, the Mozambique Belt, and other units. Geospatial data from Fritz et al. (2013)
and Macgregor (2015). Refer to Kabete et al. (2012, Figure 5)for a detailed geological map of Tanzania. Refer to Scoon (2018, Figure 2.2)for a simplified stratigraphic
column of East Africa. (b) Major geological outcrops in the greater Oldupai Gorge region. Faults after Hay (1976).
Lithic Raw Materials
Lithic industries including Earlier Stone Age (ESA), Middle
Stone Age, and Later Stone Age assemblages are preserved
in Oldupai’s sedimentary record spanning from the Early
Pleistocene to the Holocene (Leakey, 1971; Leakey et al., 1972;
Mabulla, 1990; Leakey and Roe, 1994; Eren et al., 2014). While
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Favreau et al. Raw Material Characterization at Oldupai
technological changes and the preferential use of certain rock
types are evident (Leakey, 1971; Hay, 1976; Kyara, 1999), local
raw material sources remained largely unchanged apart from
two key exceptions: (1) chert formed during saline alkaline
lake conditions and was subsequently exposed at lowstands
(Hay, 1968, 1976; O’Neil and Hay, 1973; Stiles et al., 1974); and
(2) conglomerates became available in the paleobasin through
changes in regional drainage patterns that transported gravel-
sized clasts of igneous origin from the NVH (Hay, 1976). With
such a diverse array of exploitable rock types conducive for tool-
making (Hay, 1976; Jones, 1994), hominins are believed to have
applied some stone selection criteria. Proximity to raw material
sources in the paleobasin also appears to have made long-distance
transport of exotic rock types infrequent during Oldowan and
Acheulean times (Leakey, 1971; Hay, 1976). Collectively, these
factors make lithic raw material studies important to better
understand the complexities of hominin resource procurement
within a raw material-rich paleoecological setting such
as Oldupai.
Our ability to understand hominin behavior from a techno-
ecological perspective is hindered by two factors. First, it is well-
documented that raw material morphometry and mechanical
properties, at and beyond Oldupai, affect the classification
of artifact assemblages (Leakey, 1971; Kyara, 1999; Archer
and Braun, 2010), and the behavioral interpretations gleaned
from them such as the technical abilities of their makers
(Jones, 1979, 1994). Second, while previous studies on Oldupai’s
lithic raw materials relied on macroscopic, petrographic,
and geochemical techniques, they have not comprehensively
characterized quartzitic outcrops (Leakey, 1971; Stiles et al., 1974;
Hay, 1976; Stiles, 1991, 1998; Jones, 1994; Leakey and Roe,
1994; Kyara, 1999; Mollel, 2002; Tactikos, 2005; Blumenschine
et al., 2008; Santonja et al., 2014; McHenry and de la Torre,
2018). Most recently, Egeland et al. (2019) studied local outcrops
using a portable X-Ray Fluorescence spectroscope for chemical
characterization and a Schmidt Hammer to determine fracture
predictability. Based on statistical analyses, they assign Naibor
Soit Kubwa as the likely source for three quartzite lithics from
BK East (Bed II) (Egeland et al., 2019). Apart from this most
recent study, the lack of characterization studies is unwarranted
for several reasons. Most notably, research at Oldupai has
been ongoing for over a century (Kent, 1978; Leakey, 1978;
Hay, 1990), quartzite artifacts are ubiquitous (Leakey, 1971;
Leakey and Roe, 1994), quartzite is of assumed importance
based on experimental studies (Diez-Martín et al., 2011; de
la Torre et al., 2013; Gurtov and Eren, 2014; Yustos et al.,
2015; Byrne et al., 2016), and certain quartzitic outcrops have
played a central role in discussions about hominin behavior
in the Oldupai paleobasin (Leakey, 1971; Hay, 1976; Tactikos,
2005; Blumenschine et al., 2008). We previously developed a
multi-scalar approach to characterize quartzites from different
outcrops near Oldupai (Soto et al., 2020a), which integrates
macroscopic properties, petrographic features, and chemical
compositional data. In this study, we seek to provide detailed
petrographic descriptions of lithologies in the Oldupai region
and establish the prospects of sourcing stone tools based on
petrographic data.
MATERIALS AND METHODS
Field Sampling
As part of the Stone Tools, Diet, and Sociality project, we
sampled outcrops whose locations were determined from
previous studies (Leakey, 1965, 1971; Hay, 1973, 1976; O’Neil
and Hay, 1973; Stiles et al., 1974; Jones, 1979, 1981, 1994;
Stiles, 1991, 1998; Manega, 1993; Kimura, 1997; Kyara, 1999;
Hay and Kyser, 2001; Mollel, 2002, 2007; Plummer, 2004;
Tactikos, 2005; Blumenschine et al., 2008, 2012; McHenry
et al., 2008; Mollel et al., 2008; Berry, 2012; Mollel and Swisher,
2012; Zaitsev et al., 2012; Santonja et al., 2014) and knowledge
gleaned from the local Maasai community. Samples were
split using a geological hammer, photographed, and GPS
coordinates were recorded using a Garmin eTrex 10. Structural
and lithostratigraphic characteristics were noted for each
outcrop. The samples studied herein covered the macroscopic
varieties from most of the major outcrops in the Oldupai
region (Table 1;Supplementary Table 1; see Soto et al., 2020a),
including Endonyo Osunyai (n=3) (Supplementary Figure 1),
Engelosin (n=4) (Supplementary Figure 2), the Gol
Mountains (n=10) (Supplementary Figure 3), Granite Falls
(n=4) (Supplementary Figure 4), Kelogi (n=4)
(Supplementary Figure 5), Naibor Soit Kubwa (n=16)
(Supplementary Figure 6), Naibor Soit Ndogo (n=5)
(Supplementary Figure 6), Naisiusiu (n=8) (Supplementary
Figure 7), Oittii (n=4) (Supplementary Figure 6), and Olbalbal
(n=4) (Supplementary Figure 8).
Macroscopic Description
We conducted a macroscopic description of our samples as
part of our multi-scalar characterization of raw materials
(Soto et al., 2020a). Recorded criteria included morphology,
Munsell color, grain size, texture, gloss, transparency, mineral
composition, impurities, post-depositional alterations, and
foliation. From our sample population, 38 quartzites were
classified into 10 of 13 Raw Material Groups established for
the Oldupai region (Tables 1,4;Supplementary Table 2)
(Soto et al., 2020a).
Thin Sectioning and Petrographic Analysis
Ten thin sections analyzed for this study were prepared at
the Geoscience Research Laboratory (University of Calgary).
The remaining samples were thin sectioned at the Tropical
Archaeology Lab (University of Calgary) where these were cut
flat (Trim Saw, TS10, Lortone Inc.; IsoMet 4000 Linear Precision
Saw), slide-mounted on frosted slides (27 ×46 mm) (Cast
N’ Vac 1000 Castable Vacuum System), ground to 30–35 µm
(PetroThin Thin Sectioning System), and polished (Metaserv
2000 Grinder Polisher).
A total of 74 thin sections were analyzed using a Leitz
HM-POL petrographic microscope (2.5, 4, 10, 40×) (Table 1).
Observation under plane-polarized and cross-polarized light
allowed for mineral identification and rock type classification
(Streckeisen, 1976; Le Bas and Streckeisen, 1991; Gill, 2010;
Bucher and Grapes, 2011). Each rock’s modal abundances
were visually estimated by comparison with charts (Terry and
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Favreau et al. Raw Material Characterization at Oldupai
TABLE 1 | Sample position, outcrop/source, ID, rock type, raw material group, number of thin sections per sample, and samples analyzed by SEM-EDS/EPMA.
Position Outcrop/source Sample ID Rock type Raw material
group
Thin sections,
n
SEM-EDS/EPMA
analysis
Primary Endonyo Osunyai Endonyo Osunyai 1 Quartzite W3 1 No
Endonyo Osunyai 2 Quartzite W3 1 No
Endonyo Osunyai 4A/B Quartzite GR2 2 No
Engelosin Engelosin 2 Phonolite n/a 1 No
Engelosin 5A/B Phonolite n/a 2 No
Engelosin 6A/B Phonolite n/a 2 No
Engelosin 10A/B Phonolite n/a 2 No
Gol Mountains DDD1 Quartzite GR2 1 No
JJJ1 Meta-monzo-
granite
n/a 1 No
KKK1 Meta-quartz-rich
granitoid
n/a 1 No
OOO1 Feldspar n/a 1 No
PPP1 Quartzite W3 1 No
RRR1 Quartzite G1 1 No
SSS1 Quartzite GR2 1 No
TTT1 Meta-quartz-rich
granitoid
n/a 1 No
UUU1 Meta-quartz-rich
granitoid
n/a 1 No
Granite Falls Granite Falls 1A/B Granite gneiss n/a 2 No
Granite Falls 2 Granite gneiss n/a 1 No
Kelogi Kelogi 1 Granite gneiss n/a 1 No
Kelogi 3 Granite gneiss n/a 1 No
Kelogi 10 Granite gneiss n/a 1 Yes
Naibor Soit Kubwa Naibor Soit Kubwa N042 Quartzite R3 1 No
Naibor Soit Kubwa E039 Quartzite W1 1 No
Naibor Soit Kubwa S06 Quartzite W3 1 No
Naibor Soit Kubwa 1 Quartzite R3 1 No
Naibor Soit Kubwa 2 Quartzite W3 1 No
Naibor Soit Kubwa 6 Quartzite GR1 1 Yes
Naibor Soit Kubwa 8 Quartzite R3 1 No
Naibor Soit Kubwa 11 Quartzite W3 1 No
Naibor Soit Kubwa 13 Quartzite R3 1 No
Naibor Soit Kubwa 14 Quartzite W2 1 No
Naibor Soit Kubwa 24 Quartzite W2 1 No
Naibor Soit Kubwa 27 Quartzite R3 1 No
Naibor Soit Kubwa 28 Quartz amphibolite n/a 1 No
Naibor Soit Kubwa 31 Quartzite G1 1 No
Naibor Soit Kubwa 32 Quartzite GR1 1 No
Naibor Soit Kubwa 33 Quartzite GR1 1 No
Naibor Soit Ndogo Naibor Soit Ndogo 6A/B Quartzite W3 2 No
Naibor Soit Ndogo 8 Quartzite W3 1 No
Naibor Soit Ndogo 13 Quartzite W2 1 Yes
Naibor Soit Ndogo 14 Quartzite G1 1 No
Naibor Soit Ndogo 15 Quartzite W3 1 No
(Continued)
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Favreau et al. Raw Material Characterization at Oldupai
TABLE 1 | Continued
Position Outcrop/source Sample ID Rock type Raw material
group
Thin sections,
n
SEM-EDS/EPMA
analysis
Naisiusiu Naisiusiu 3 Meta-syeno-
granite
n/a 1 No
Naisiusiu 4 Quartzite GR2 1 Yes
Naisiusiu 7 Quartzite GR1 1 Yes
Naisiusiu 8 Mica schist n/a 1 No
Naisiusiu 9 Quartzite W4 1 No
Naisiusiu 13 Quartzite GR1 1 No
Naisiusiu 14 Quartzite W3 1 No
Oittii Oittii 1A/B Quartzite GR2 2 No
Oittii 3 Quartzite W4 1 No
Oittii 4 Quartzite GR2 1 No
Oittii 5A/B Quartzite GR2 2 No
Secondary Gol Mountains III1 Hornblende
granofels
n/a 1 Yes
Granite Falls Granite Falls 3A/B Nephelinite n/a 2 No
Granite Falls 4A/B Quartzite W3 2 No
Kelogi Kelogi 9 Quartzite GR3 1 Yes
Naisiusiu Naisiusiu 12 Nephelinite n/a 1 Yes
Olbalbal A1A/B Nephelinite n/a 2 Yes
A2 Basalt n/a 1 No
A5A/B Basalt n/a 2 No
A6 Trachyandesite/basalt n/a 1 Yes
Chilingar, 1955). Textural characteristics such as crystal habit,
morphology, replacement textures, intergrowths, and foliation
were noted depending on rock type, and qualitative grain
sizes were recorded (Supplementary Material Petrographic
Descriptions; Supplementary Table 3). Photomicrographs were
taken using a Nikon ECLIPSE 50i POL microscope (2, 4,
10, 40×) equipped with a Moticam 2500 (Motic Images
Plus 2.0).
SEM-EDS and EPMA
Ten thin sections (Table 1) were analyzed at the Instrumentation
Facility for Analytical Electron Microscopy (University of
Calgary) using a FEI Quanta 250 FEG system equipped
with a Bruker Quantax EDS for semi-quantitative analysis
and backscatter electron (BSE) imaging. Observations and
analyses were performed under an acceleration voltage of
15 kV, a pressure of 50Pa, and a measuring time of 20 s.
Spectra obtained from targeted minerals were identified by
comparison with those from common rock forming minerals
(Severin, 2004).
The 10 thin sections analyzed by SEM-EDS were also
studied by EPMA (Table 1) at the University of Calgary
Laboratory for Electron Microprobe Analysis, which enabled
more accurate characterization of small grains. The laboratory
houses a JEOL JXA-8200 electron microprobe with BSE imaging
capabilities and a Bruker EDS system for semi-quantitative
analysis. Samples were first carbon-coated, and observations
and analyses were performed under an acceleration voltage of
15 kV, an emission current of 12 µA, and a measuring time
of 20 s.
RESULTS
The following sections, organized alphabetically by outcrop
name, provide the geologic context for each outcrop and
petrographic descriptions of samples.
Endonyo Osunyai
Geology
Endonyo Osunyai consists of sporadically exposed quartzites
and gneisses along a ∼100 m long stretch northwest of Naibor
Soit Kubwa (Figure 1b). Quartzite is foliated and the foliation
planes display a dominantly southerly dip with some exceptions
(Figure 2A;Supplementary Figure 9). Gneissic lithologies are
exposed along the northwestern part of the exposures where
they show meso-scale deformation fabrics including folds
(Figure 2B).
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Favreau et al. Raw Material Characterization at Oldupai
FIGURE 2 | Endonyo Osunyai: (A) Quartzites with foliation planes dipping south; (B) fractured gneiss outcrops showing one asymmetrical fold with harmonic folding;
Engelosin: (C) weathered, oxidized, and fractured phonolite; (D) talus accumulations of phonolitic breccia cemented by calcrete; Gol Mountains: (E) west of Kesile,
complexly deformed and exfoliated north-south trending granite gneiss outcrop with steeply-dipping foliation planes; (F) view south toward the rockshelter at Soit
Nasera, a quartz-feldspathic monolith.
Petrography
Prior studies have identified gneiss and quartzite at Endonyo
Osunyai, but no petrographic descriptions are available
(Hay, 1976; Kyara, 1999). The quartzite is coarse-grained
and accessory minerals include alkali feldspar, muscovite,
hematite, and rutile (Figures 3A,B;Supplementary Figure 10)
(Table 2) (Supplementary Section 1.1). Quartz crystals
predominantly have sutured boundaries as a result of
dynamic recrystallization (Stipp et al., 2002). Muscovite
crystals have a platy habit, are either interstitial to or occur as
inclusions in quartz, and generally show preferred alignment.
Muscovite is responsible for weak foliation in samples
containing alkali feldspar. No relict sedimentary textures
are preserved.
Engelosin
Geology
Engelosin is a 150 m-high, weathered and oxidized
phonolitic volcanic neck north of Oittii (Figures 1b,2C;
Supplementary Figure 11) (Mollel and Swisher, 2012). Eroded
clasts and detritus from this outcrop are believed to have drained
into the Oldupai paleobasin in combination with input from
other volcanic centers of the NVH (Hay, 1976; Dawson, 2008;
Mollel and Swisher, 2012). Volcaniclastic phonolitic breccia,
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Favreau et al. Raw Material Characterization at Oldupai
TABLE 2 | Visually estimated modal percentages per sample.
Position Outcrop/source Sample ID Rock type Mineralogy
Primary Endonyo Osunyai Endonyo Osunyai 1 Quartzite Quartz (98); muscovite (2); opaque (<1); rutile (<1)
Endonyo Osunyai 2 Quartzite Quartz (98); muscovite (2); opaque (<1)
Endonyo Osunyai 4A Quartzite Quartz (79); alkali feldspar (15); muscovite (5); hematite (1)
Endonyo Osunyai 4B Quartzite Quartz (78); alkali feldspar (10); muscovite (10); hematite (2)
Engelosin Engelosin 2 Phonolite Sanidine (5); nepheline (1); titanite (<1); sericite (<1)
Engelosin 5A Phonolite Sanidine (2); nepheline (1); augite (1); titanite (<1); sericite
(<1)
Engelosin 5B Phonolite Nepheline (1); sanidine (1); augite (1); sericite (<1); titanite
(<1)
Engelosin 6A Phonolite Sanidine (1); nepheline (<1); augite (<1); sericite (<1);
titanite (<1)
Engelosin 6B Phonolite Nepheline (1); sanidine (1); augite (<1); sericite (<1)
Engelosin 10A Phonolite Sanidine (5); augite (<1); titanite (<1); nepheline (<1)
Engelosin 10B Phonolite Sanidine (5); titanite (1); augite (1); nepheline (<1)
Gol Mountains DDD1 Quartzite Quartz (90); muscovite (10); alkali feldspar (<1)
JJJ1 Meta-monzo-granite Quartz (45); alkali feldspar (40); biotite (15); plagioclase (<1);
rutile (<1)
KKK1 Meta-quartz-rich
granitoid
Quartz (60); alkali feldspar (20); biotite (12); hornblende (6);
plagioclase (2)
OOO1 Feldspar Microcline (73); albite (25); hematite (1); opaque (1); sanidine
(<1)
PPP1 Quartzite Quartz (95); muscovite (5); rutile (<1); opaque (<1)
RRR1 Quartzite Quartz (90); muscovite (10); rutile (<1)
SSS1 Quartzite Quartz (92); muscovite (8); rutile (<1)
TTT1 Meta-quartz-rich
granitoid
Quartz (70); biotite (10); plagioclase (10); alkali feldspar (8);
opaque (2)
UUU1 Meta-quartz-rich
granitoid
Quartz (70); biotite (10); alkali feldspar (10); plagioclase (5);
opaque (3); muscovite (2)
Granite Falls Granite Falls 1A Granite gneiss Quartz (50); alkali feldspar (30); biotite (15); muscovite (5);
plagioclase (<1)
Granite Falls 1B Granite gneiss Quartz (60); alkali feldspar (20); biotite (10); muscovite (8);
plagioclase (2)
Granite Falls 2 Granite gneiss Quartz (69); alkali feldspar (15); plagioclase (10); muscovite
(5); biotite (1)
Kelogi Kelogi 1 Granite gneiss Quartz (40); aegirine (20); plagioclase (15); alkali feldspar
(15); hornblende (10)
Kelogi 3 Granite gneiss Quartz (45); aegirine (20); hornblende (12); plagioclase (12);
hematite (8); alkali feldspar (3)
Kelogi 10 Granite gneiss Plagioclase (25); quartz (25); hornblende (20); aegirine (20);
alkali feldspar (10); titanite (<1); biotite (<1); zircon (<1)
Naibor Soit Kubwa Naibor Soit Kubwa N042 Quartzite Quartz (85); muscovite (15); hematite (<1)
Naibor Soit Kubwa E039 Quartzite Quartz (92); muscovite (8)
Naibor Soit Kubwa S06 Quartzite Quartz (95); muscovite (5)
Naibor Soit Kubwa 1 Quartzite Quartz (93); muscovite (5); hematite (1); rutile (1)
Naibor Soit Kubwa 2 Quartzite Quartz (95); muscovite (5); rutile (<1); opaque (<1)
Naibor Soit Kubwa 6 Quartzite Quartz (92); muscovite (5); rutile (1); opaque (1); fuchsite (1);
anhydrite (<1)
Naibor Soit Kubwa 8 Quartzite Quartz (94); muscovite (6); opaque (<1); rutile (<1)
Naibor Soit Kubwa 11 Quartzite Quartz (98); muscovite (2); rutile (<1)
Naibor Soit Kubwa 13 Quartzite Quartz (92); muscovite (8); rutile (<1)
Naibor Soit Kubwa 14 Quartzite Quartz (92); muscovite (8)
(Continued)
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TABLE 2 | Continued
Position Outcrop/source Sample ID Rock type Mineralogy
Naibor Soit Kubwa 24 Quartzite Quartz (99); muscovite (1); opaque (<1)
Naibor Soit Kubwa 27 Quartzite Quartz (70); muscovite (30)
Naibor Soit Kubwa 28 Quartz amphibolite Hornblende (40); epidote (32); quartz (24); opaque (3);
plagioclase (1); calcite (<1)
Naibor Soit Kubwa 31 Quartzite Quartz (92); muscovite (8)
Naibor Soit Kubwa 32 Quartzite Quartz (85); muscovite (14); rutile (1); fuchsite (<1)
Naibor Soit Kubwa 33 Quartzite Quartz (97); muscovite (3); magnetite (<1)
Naibor Soit Ndogo Naibor Soit Ndogo 6A Quartzite Quartz (95); muscovite (5)
Naibor Soit Ndogo 6B Quartzite Quartz (95); muscovite (5)
Naibor Soit Ndogo 8 Quartzite Quartz (98); muscovite (2)
Naibor Soit Ndogo 13 Quartzite Quartz (96); muscovite (3); fuchsite (1); rutile (<1); opaque
(<1); anhydrite (<1)
Naibor Soit Ndogo 14 Quartzite Quartz (98); muscovite (2); fuchsite (<1)
Naibor Soit Ndogo 15 Quartzite Quartz (95); muscovite (5); opaque (<1); hematite (<1); rutile
(<1)
Naisiusiu Naisiusiu 3 Meta-syeno-granite Quartz (45); alkali feldspar (35); plagioclase (10); opaque (7);
biotite (2); hornblende (1)
Naisiusiu 4 Quartzite Quartz (85); biotite (13); muscovite (1); opaque (Cr-bearing
rutile) (1); secondary mica (1); plagioclase (<1); albite (<1);
apatite (<1); anhydrite (<1); tschermakite (<1)
Naisiusiu 7 Quartzite Quartz (94); chlorite (4); muscovite (1); opaque (1); calcite
(<1); alkali feldspar (<1); plagioclase (<1); apatite (<1);
glauconite (<1)
Naisiusiu 8 Mica schist Muscovite (75); quartz (15); biotite (10); plagioclase (<1)
Naisiusiu 9 Quartzite Quartz (95); muscovite (5)
Naisiusiu 13 Quartzite Quartz (97); muscovite (2); hematite (1); opaque (<1)
Naisiusiu 14 Quartzite Quartz (94); muscovite (5); opaque (1)
Oittii Oittii 1A Quartzite Quartz (93); muscovite (3); hematite (3); rutile (1)
Oittii 1B Quartzite Quartz (93); muscovite (3); hematite (3); rutile (1)
Oittii 3 Quartzite Quartz (85); muscovite (10); alkali feldspar (5); plagioclase
(<1)
Oittii 4 Quartzite Quartz (96); muscovite (2); hematite (1); rutile (1)
Oittii 5A Quartzite Quartz (85); muscovite (15); alkali feldspar (<1)
Oittii 5B Quartzite Quartz (85); muscovite (15); alkali feldspar (<1)
Secondary Gol Mountains III1 Hornblende granofels Hornblende (50); quartz (48); opaque (ilmenite) (2); alkali
feldspar (<1); plagioclase (<1)
Granite Falls Granite Falls 3A Nephelinite Nepheline (5); opaque (3); aegirine-augite (<1); sanidine
(<1)
Granite Falls 3B Nephelinite Nepheline (5); opaque (3); aegirine-augite (<1); sanidine
(<1)
Granite Falls 4A Quartzite Quartz (95); muscovite (5)
Granite Falls 4B Quartzite Quartz (95); muscovite (5)
Kelogi Kelogi 9 Quartzite Quartz (86); staurolite (8); muscovite (3); kyanite (2); opaque
(ilmenite) (1); apatite (<1); zircon (<1)
Naisiusiu Naisiusiu 12 Nephelinite Nepheline (5); aegirine-augite (1); sanidine (<1); hornblende
(<1); opaque (ilmenite) (<1); alkali feldspar (<1); apatite
(<1); secondary quartz (<1)
(Continued)
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Favreau et al. Raw Material Characterization at Oldupai
TABLE 2 | Continued
Position Outcrop/source Sample ID Rock type Mineralogy
Olbalbal A1A Nephelinite Nepheline (65); aegirine-augite (10); hornblende (1); titanite
(<1); titanoaugite (<1); wollastonite (<1); apatite (<1); calcic
plagioclase (<1); Cl-bearing silicates (<1)
A1B Nephelinite Nepheline (65); aegirine-augite (10); hornblende (1); titanite
(<1); titanoaugite (<1); wollastonite (<1); apatite (<1); calcic
plagioclase (<1); Cl-bearing silicates (<1)
A2 Basalt Plagioclase (20); opaque (1); augite (1); olivine (1)
A5A Basalt Plagioclase (1); augite (<1)
A5B Basalt Plagioclase (1); augite (<1)
A6 Trachyandesite/basalt Plagioclase (1); kaersutite (1); augite (<1); alkali feldspar
(<1); pyroxene (<1); ilmenite (<1); magnetite (<1)
Modes for igneous rocks are for phenocrysts. Modes for Kelogi 1 and 3 are based on point counts instead of visual estimates.
formed by calcrete cementation of talus fragments, blanket the
unweathered parts of the volcanic neck (Figure 2D).
Petrography
Engelosin phonolite is green to gray, fine- to medium-
grained, and exhibits a variety of porphyritic and vesicular
textures. Previous studies show alkali feldspar (anorthoclase
and sanidine), augite, nepheline, aegirine, analcime, titanite,
and apatite as constituent minerals (Hay, 1976; Kyara, 1999;
Mollel and Swisher, 2012). We identified several phenocrysts
including sanidine, nepheline, augite, and titanite together
with minor amounts of sericite as an alteration product of
feldspars (Figures 3C,D;Supplementary Figure 12) (Table 2)
(Supplementary Section 1.2). Oxide phases are readily visible
under thin section. Based on textural and mineralogical
differences among four samples, there is one flow-aligned variety
and a second with a felty texture (Table 3).
Gol Mountains
Geology
The Gol Mountains refers to primarily metamorphic inselbergs
that transition northwards into a mountain range. These
inselbergs begin to outcrop ∼4 km north of Engelosin and belong
to the Mozambique Belt (Figures 1a,b). These outcrops represent
a highly deformed complex that is typical of mobile belts
(Figure 2E) (Scoon, 2018). The lithologies include limestones,
schists, gneisses, quartzites, and migmatites (Cahen and Snelling,
1966; Cahen et al., 1984), which are occasionally oxidized and
capped by calcretes. During the wet season, many inselbergs
are drained by streams capable of transporting clasts several
kilometers away (Supplementary Figure 13A). The local roads
are sometimes bordered by lustrous phyllite which originates
from a northern source according to local Maasai knowledge.
One of the most iconic inselbergs of the Gol Mountains is
Soit Nasera (Figure 1b) (Scoon, 2018), a 350 m-high quartz-
feldspathic monolith that is complexly deformed, faulted,
exfoliated, varnished, and contains quartz veins and feldspar
(Figure 2F). West and south of Soit Nasera are a variety of other
inselbergs and low-lying outcrops composed of meta-granites
and quartzites (Figure 1b;Supplementary Figures 13C,E,F).
A total of nine samples from the Gol Mountains were
analyzed in this study (Supplementary Figure 3) (Table 1;
Supplementary Table 1).
Petrography
Previous studies reported quartzite at Olongojoo and near
Soit Nasera but no detailed descriptions are available (Hay,
1976; Mehlman, 1977; Blumenschine et al., 2008; Reti, 2013).
Accessory minerals present in coarse- and medium-grained
quartzites include muscovite, alkali feldspar, and rutile (Table 2)
(Supplementary Section 1.3). Quartz crystals exhibit sutured
boundaries. Muscovite occurs as variably-sized platy crystals
that are either interstitial to or included in quartz, and
have either a random distribution or exhibit parallel lineation
(Figures 3E,F). Muscovite crystals are responsible for weak
foliation in one sample. Two samples show rutile concentrations
or heavy mineral accumulations, likely a function of the original
sedimentary protolith. Alkali feldspar and rutile are rare, but
the overall mineralogy is consistent with a sandstone protolith
although no relict sedimentary textures are preserved.
Meta-granites contain quartz, alkali feldspar, biotite,
hornblende, plagioclase, rutile, and muscovite (Table 2)
(Supplementary Section 1.3). All samples show hypidiomorphic
textures. Quartz crystals show weak undulatory extinction and
one sample contains granophyric intergrowths with alkali
feldspar. Biotite, hornblende, and opaque crystals are responsible
for the spotted and weakly foliated textures.
One sample of fine-grained leucocratic feldspar from Soit
Nasera contains microcline, albite, hematite, opaque crystals, and
sanidine (Table 2) (Supplementary Section 1.3). Similar rock
types have been reported near Granite Falls but no petrographic
descriptions are available (Hay, 1971, 1976).
One sample of fine-grained homeoblastic granofels contains
hornblende, quartz, ilmenite, alkali feldspar, and plagioclase
(Table 2) (Supplementary Section 1.3). Quartz crystals are
generally euhedral with a granoblastic texture, and minor
amounts are slightly deformed. SEM-EDS and EPMA analysis
confirmed the presence of hornblende, quartz, and plagioclase,
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Favreau et al. Raw Material Characterization at Oldupai
FIGURE 3 | Endonyo Osunyai 2: (A) Lineated muscovite in quartz (PPL 2×horizontal field width 1.1 mm); (B) same as (A), quartz crystals show undulatory extinction
and corrugated boundaries (XP); Engelosin 2: (C) flow-aligned microphenocrysts of sanidine (XP 4×horizontal field width 0.55 mm); (D) sub-parallel sanidine
microphenocrysts and interstitial sericite with a silky texture (XP 2×horizontal field width 1.1 mm); Gol Mountains (PPP1): (E) randomly oriented muscovite included in
and interstitial to quartz (XP 2×horizontal field width 1.1 mm); Gol Mountains (DDD1): (F) sub-parallel muscovite included in and interstitial to quartz (XP 2×horizontal
field width 1.1 mm); Kelogi 10: (G) hornblende and aegirine (PPL 4×horizontal field width 0.55 mm); (H) plagioclase, quartz, hornblende, and aegirine (XP 4×
horizontal field width 0.55 mm).
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Favreau et al. Raw Material Characterization at Oldupai
TABLE 3 | Textural data per magmatic sample.
Sample ID Rock type Porphyry Porphyritic
texture
Groundmass Groundmass
texture
Engelosin 2 Phonolite Microporphyritic Flow-aligned Light-green Trachytic
Engelosin 5A Phonolite Microporphyritic Felty Light-green Felty
Engelosin 5B Phonolite Microporphyritic Felty Light-green Felty
Engelosin 6A Phonolite Microporphyritic Flow-aligned Light-green Trachytic
Engelosin 6B Phonolite Microporphyritic Flow-aligned Light-green Trachytic
Engelosin 10A Phonolite Microporphyritic Flow-aligned Light-gray Trachytic
Engelosin 10B Phonolite Microporphyritic Flow-aligned Light-gray Trachytic
Granite Falls 3A Nephelinite Microporphyritic Weakly aligned Light-brown Flow-aligned
Granite Falls 3B Nephelinite Microporphyritic Weakly aligned Light-brown Flow-aligned
Naisiusiu 12 Nephelinite Microporphyritic Flow-aligned Brown-gray Flow-aligned
A1A Nephelinite Porphyritic Weakly aligned Dark-brown Weakly aligned
A1B Nephelinite Porphyritic Weakly aligned Dark-brown Weakly aligned
A2 Basalt Porphyritic Flow-aligned Light-gray Trachytic
A5A Basalt Porphyritic Flow-aligned Light-gray Trachytic
A5B Basalt Porphyritic Flow-aligned Light-gray Trachytic
A6 Trachyandesite/basalt Microporphyritic Felty Light-gray Felty
and allowed the identification of opaque crystals seen under thin
section as ilmenite (Supplementary Figures 14, 15). This sample
was collected in a seasonal stream channel draining Olongojoo
(Figure 1b;Supplementary Figure 13A) which suggests that
granofelsic rocks are present at this inselberg in addition to
quartzite (Hay, 1976; Blumenschine et al., 2008).
Granite Falls
Geology
Granite Falls comprise metamorphosed granitic lithologies
that underlie the sedimentary units in the western Oldupai
paleobasin (Hay, 1976). The outcrop is partly exfoliated, faulted,
and varnished while the joints trend east-west (Figure 4A;
Supplementary Figures 16A,B). The Oldupai River flows
through Granite Falls during the wet season depositing igneous
and metamorphic clasts (Supplementary Figures 16C,D).
Petrography
Hay (1976) reported quartz, microcline, plagioclase, biotite,
and muscovite in gneiss rocks from this outcrop. Granite
gneiss samples analyzed in this study contain quartz,
alkali feldspar, biotite, muscovite, and plagioclase (Table 2)
(Supplementary Section 1.4). Some thin sections have
granoblastic textures while others are highly deformed. One
sample contained deformed quartz with crack-seal structures
filled by muscovite microveins. Muscovite predominantly occurs
as platy crystals that are either interstitial to or included in other
crystals. Biotite is the defining foliation mineral.
One sample of nephelinite recovered from the riverbed
(Supplementary Figure 16C) is inequigranular and contains
nepheline, aegirine-augite, and sanidine microphenocrysts
which are included in a flow-aligned light-brown groundmass
(Tables 2,3) (Supplementary Section 1.4). This sample
originates from Sadiman based on mineralogical similarities
(Zaitsev et al., 2012).
One sample of quartzite discovered in the riverbed
(Supplementary Figure 16D) is weakly foliated with a
heteroblastic texture, and has a mineral assemblage of quartz and
rare muscovite (Table 2) (Supplementary Section 1.4). Quartz
crystals have sutured boundaries. Muscovite crystals are either
interstitial to or inclusions in quartz, have a parallel lineation,
and are occasionally lozenge-shaped with fragment trails. This
sample’s source is unknown and does not resemble quartzites
from Naisiusiu.
Kelogi
Geology
Kelogi refers to a series of northeast-southwest trending
granite gneiss inselbergs west of the Side Gorge (Figure 1b).
The outcrops are distributed over ∼2 km and are complexly
deformed, faulted, exfoliated, varnished, and contain quartz and
mafic veins occasionally oriented perpendicular to weak foliation
planes (Figures 4B,C;Supplementary Figure 17). Kelogi clasts
and detritus contributed to sedimentary infill of the Oldupai
paleobasin (Hay, 1976).
Petrography
Previous studies of granite gneiss have reported quartz,
orthoclase, albite, aegirine, hornblende, biotite, and garnet
(Hay, 1976; Kyara, 1999). Medium- to fine-grained granite
gneiss samples analyzed in this study contain quartz, aegirine,
plagioclase, hornblende, alkali feldspar, hematite, titanite,
biotite, and zircon (Table 2) (Supplementary Section 1.5).
Quartz crystals are anhedral and commonly show undulatory
extinction. Hornblende and aegirine define foliation resulting in
a gneissose texture (Figures 3G,H;Supplementary Figure 18).
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Favreau et al. Raw Material Characterization at Oldupai
FIGURE 4 | Granite Falls: (A) View east showing jointed granite gneiss forming the riverbed of the seasonal Olduvai River; Kelogi: (B) complexly deformed, weathered,
and varnished granite gneiss; (C) close-up of a quartz and mafic vein; Naibor Soit Kubwa: (D) quartzite with foliation planes dipping west overlain by gneiss outcrops;
(E) magnetite-rich quartzite on the eastern side of the inselberg; (F) portion of the amphibolite dyke with sub-parallel quartz veins.
Zircons were identified under SEM-EDS and EPMA
(Supplementary Figures 19, 20).
One quartzite sample in secondary position is fine-grained,
and has a mineral assemblage of quartz, staurolite, muscovite,
kyanite, ilmenite, zircon, and apatite (Figures 5A,B) (Table 2)
(Supplementary Section 1.5). Quartz crystals are anhedral and
show undulatory extinction. Muscovite and kyanite crystals
are either interstitial to or occur as inclusions in quartz,
and have a parallel lineation. SEM-EDS and EPMA analysis
allowed the identification of zircon and apatite, and helped
identify opaque crystals seen under thin section as ilmenite
(Figures 6A,B;Supplementary Figures 21, 22). This sample
originates from either Endonyo Okule or Naisiusiu based on
mineralogical similarities (see section Quartzites) (Hay, 1976:
Table 6).
Naibor Soit Kubwa
Geology
Naibor Soit Kubwa is a ∼1.8 km-long, northwest-southeast
trending quartzitic and gneissic inselberg west of Naibor Soit
Ndogo (Figure 1b). Most of the foliation planes dip northwest,
west, or southwest (Figures 4D,E;Supplementary Figure 23).
The outcrop principally consists of coarse- to medium-
grained varieties of white, gray, orange, pink, red, and green
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Favreau et al. Raw Material Characterization at Oldupai
FIGURE 5 | Kelogi 9: (A) Quartz, staurolite, muscovite, and kyanite (PPL 4×horizontal field width 0.55 mm); (B) similar to (A) note the fine-grained texture (XP 2×
horizontal field width 1.1 mm); Naibor Soit Kubwa 33: (C) sub-parallel muscovite crystals included in and interstitial to quartz (XP 2×horizontal field width 1.1 mm);
(D) magnetite crystal with dark metallic luster and a dendritic habit (PPL 40×horizontal field width 0.055 mm); Naibor Soit Kubwa 28: (E) foliation defined by
hornblende (PPL 2×horizontal field width 1.1 mm); (F) plagioclase crystal with characteristic polysynthetic twinning surrounded by quartz and epidote (XP 10×
horizontal field width 0.22 mm); Naibor Soit Ndogo 13 (thin section damaged during preparation): (G) pale green fuchsite crystals and colorless muscovite included in
and interstitial to quartz (PPL 2×horizontal field width 1.1 mm); (H) same as (G) note the platy habit of fuchsite and muscovite (XP).
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Favreau et al. Raw Material Characterization at Oldupai
FIGURE 6 | X-ray spectra (EDS) of minerals obtained using EPMA: (A) Staurolite and (B) kyanite in Kelogi 9; (C) anhydrite in Naibor Soit Kubwa 6; (D) fuchsite in
Naibor Soit Ndogo 13; (E) biotite in Naisiusiu 4; (F) glauconite in Naisiusiu 7; (G) wollastonite in A1A; (H) kaersutite in A6. Refer to Table 2 and
Supplementary Section 1 for additional sample information. Refer to Supplementary Figures 22, 27, 33, 37, 39, 46, 49 for unclipped spectra.
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Favreau et al. Raw Material Characterization at Oldupai
quartzites that are occasionally oxidized and capped by calcretes
(Supplementary Figure 23). The inselberg’s clasts and detritus
contributed to sedimentary infill of the Oldupai paleobasin
(Hay, 1976). Protruding through the top of the inselberg in the
northwestern sector is a prominent amphibolite dyke with sub-
parallel quartz veins (Figure 4F;Supplementary Figures 23E,F).
The northern and western sides of the outcrop bear sand deposits.
The northern deposits are aeolian and originate from nearby
barchan (mafic) sand dunes that travel westward according
to prevailing winds (Hay, 1976). The western deposits are a
combination of mafic sands and felsic erosional by-products from
the outcrop.
Petrography
Previous studies have identified gneiss and coarse-grained
quartzite with rare muscovite (Hay, 1976; Kyara, 1999; Tactikos,
2005; McHenry and de la Torre, 2018). Accessory minerals
present in coarse- to fine-grained quartzites include muscovite
and rutile, and rare hematite, fuchsite, magnetite, and anhydrite
(Figures 5C,D,6C;Supplementary Figures 24–27) (Table 2)
(Supplementary Section 1.6). Quartz crystals typically display
sutured boundaries. Muscovite crystals are either interstitial to
or included in quartz, and predominantly show parallel to sub-
parallel lineation. Muscovite crystals are responsible for foliated
quartzites. Rare occurrences of fuchsite, a chromium-rich variety
of muscovite, occur as small crystals that are either interstitial
to or included in quartz. Hematite is commonly interstitial
to quartz. The mineral assemblages of quartzite are consistent
with a sandstone protolith and one sample preserved a relict
sedimentary texture (Supplementary Section 1.6). Anhydrite
crystals are present which may be of evaporitic origin.
Fine-grained gneissose (defined by hornblende) quartz
amphibolite was sampled from a previously unrecorded meta-
mafic dyke cross-cutting the quartzite-dominated inselberg
(Figure 4F;Supplementary Figures 23E,F). The mineral
assemblage of hornblende, epidote, quartz, opaque crystals,
plagioclase, and calcite (Figures 5E,F;Supplementary
Figure 28) (Table 2) (Supplementary Section 1.6) is typical
of a basaltic protolith metamorphosed into amphibolite.
Metamorphic processes may have impacted surrounding quartz-
rich lithologies which may explain the high proportion of quartz
and the presence of foliation-parallel quartz veins (Figure 4F).
Naibor Soit Ndogo
Geology
Naibor Soit Ndogo is a ∼1 km-long, northwest-southeast
trending quartzitic inselberg east of Naibor Soit Kubwa
(Figure 1b). The westernmost quartzites have foliation planes
that steeply dip south and southwest while the easternmost
foliation planes steeply dip southwest and west (Figure 7A;
Supplementary Figure 29). The outcrop principally consists of
coarse- to medium-grained varieties of white, orange, pink,
and green quartzites that are occasionally oxidized (Figure 7B;
Supplementary Figure 29). The easternmost outcrops bear
evidence of heat-induced staining (Supplementary Figure 29D).
Petrography
Previous studies have identified coarse-grained quartzite with
a mineral assemblage of quartz and rare muscovite (Leakey,
1965; Hay, 1976; Kyara, 1999; Santonja et al., 2014; Bello-
Alonso et al., 2020). Accessory minerals present in coarse-grained
quartzites include muscovite, rare fuchsite, rutile, hematite, and
anhydrite (Figures 5G,H,6D;Supplementary Figures 30–33;
Table 2;Supplementary Section 1.7). Quartz crystals typically
display sutured boundaries. Muscovite occurs as platy crystals
that are either interstitial to or included in quartz. Muscovite
crystals generally have a parallel to sub-parallel lineation and
are responsible for weak foliation in some samples. Muscovite
crystals are occasionally lozenge-shaped with fragment trails,
and form bookshelf-sliding microstructures. Rare occurrences
of fuchsite occur as small crystals that are either included in
quartz or interstitial (Figures 5G,H;Supplementary Figure 30).
Rutile is a rare accessory mineral and hematite generally occurs
interstitial to quartz. The mineral assemblages are suggestive of
a sandstone protolith although no relict sedimentary textures
are preserved.
Naisiusiu
Geology
Naisiusiu is a low-lying, east-west trending quartzitic, schistose,
and meta-granitic outcrop ∼3 km southeast of Granite Falls
(Figures 1b,6C,D;Supplementary Figure 34). The quartzite
and schists have foliation planes dipping south. The top and
northern sides of the outcrop show greater exposure than
the southern and eastern sides likely resulting from mining
activities (Supplementary Figure 34A). The outcrop principally
consists of medium-grained varieties of white, gray, red, and
purple quartzites interlayered by mica schist (Figures 7C,D;
Supplementary Figures 34E,F) along with meta-granitic bodies
with uncertain structural relationships to the former.
Petrography
Previous studies on quartzite have identified quartz, microcline,
muscovite, garnet, kyanite, and staurolite (Hay, 1976; Kyara,
1999; Tactikos, 2005; McHenry and de la Torre, 2018). Coarse- to
fine-grained quartzites have diverse mineral assemblages, but are
mostly dominated by quartz, biotite, muscovite, opaque crystals,
hematite, and calcite (Table 2) (Supplementary Section 1.8).
Quartz crystals show undulatory extinction. Muscovite crystals
have a platy habit, are either interstitial to or inclusions in
quartz, and have a parallel to random lineation (Figures 8A,B;
Supplementary Figure 35). Some samples show variably-sized
quartz grains, quartz overgrowths, and interstitial cement which
suggest poorly-sorted sandstone protoliths. Biotite and chlorite
are responsible for weak foliation in some samples. SEM-EDS and
EPMA allowed the identification of biotite, potassium feldspar,
plagioclase, albite, apatite, anhydrite, glauconite, secondary
mica, tschermakite, and deeply-colored rutile (Figures 6E,F;
Supplementary Figures 36–39).
Previous studies on granite gneiss have identified quartz,
microcline, plagioclase, aegirine, hornblende, titanite, and biotite
as mineral constituents (Hay, 1976; Kyara, 1999). Here,
we identified quartz, alkali feldspar, plagioclase, biotite, and
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Favreau et al. Raw Material Characterization at Oldupai
FIGURE 7 | Naibor Soit Ndogo: (A) View west toward Naibor Soit Kubwa showing quartzite foliation planes steeply dipping south; (B) fuchsite-bearing quartzite on
the southern side of the inselberg; Naisiusiu: (C) quartzitic (foreground) and meta-granitic (background) lithologies on the northern side of the outcrop; (D) mica schist
overlain by quartzite with foliation planes dipping southeast; Oittii: (E) view west toward Naibor Soit Kubwa showing quartzite foliation planes dipping north;
(F) east-west trending steeply dipping mica schist with harmonic folding; Olbalbal: (G) panoramic view northwest toward Oldupai Gorge’s First Fault.
hornblende in one sample of medium- to fine-grained meta-
syeno-granite with a hypidiomorphic texture (Table 2). Quartz
crystals are anhedral and show undulatory extinction. Opaque
crystals are responsible for this rock’s spotted texture.
One sample of medium- to fine-grained mica schist
contains muscovite, quartz, biotite, and plagioclase (Table 2).
The texture is primarily lepidoblastic but partly decussate.
Muscovite crystals are responsible for the foliated texture.
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Favreau et al. Raw Material Characterization at Oldupai
FIGURE 8 | Naisiusiu 14: (A) Quartz and muscovite (PPL 2×horizontal field width 1.1 mm); (B) same as (A) quartz crystals show undulatory extinction and sutured
boundaries (XP); Oittii 1A: (C) large idioblastic rutile crystals (PPL 2×horizontal field width 1.1 mm); (D) same as (C) quartz crystals show undulatory extinction, and
muscovite crystals are fragmented and have a random lineation (XP); A6: (E) kaersutite crystals included in a felty groundmass (PPL 4×horizontal field width
0.55 mm); (F) same as (E) note the distinctive red kaersutite crystals (XP).
This rock type can be found overlain by quartzite (Figure 7D;
Supplementary Figures 34E,F).
One sample of nephelinite recovered on the surface of
the outcrop contains nepheline, aegirine-augite, sanidine, and
hornblende microphenocrysts included in a flow-aligned brown-
gray groundmass with devitrified glass and minor amounts
of oxides (Tables 2,3). SEM-EDS and EPMA allowed the
identification of potassium feldspar, secondary quartz, apatite,
and ilmenite (Supplementary Figures 40, 41). This sample
originates from Sadiman based on mineralogical similarities
(Zaitsev et al., 2012).
Oittii
Geology
Oittii is a low-lying, quartzitic and schistic outcrop north of
Naibor Soit Ndogo (Figure 1b). The metamorphosed outcrop
contains east-west trending quartzites with foliation planes
dipping north, north-south trending steeply-dipping quartzites,
and east-west trending steeply-dipping mica schist with
harmonic folding (Figures 7E,F;Supplementary Figure 42).
The outcrop principally consists of coarse-grained gray quartzites
that are highly oxidized, and large numbers of fragmented rocks
suggest recent mining activities.
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Favreau et al. Raw Material Characterization at Oldupai
Petrography
Previous studies have identified mica schist and quartzite but
no petrographic descriptions are available (Leakey, 1965; Jones,
1994; Kyara, 1999). Accessory minerals present in coarse- to fine-
grained quartzites include muscovite, alkali feldspar, hematite,
rutile, and plagioclase (Figures 8C,D;Supplementary Figure 43;
Table 2;Supplementary Section 1.9). Quartz crystals
occasionally have sutured boundaries. Muscovite crystals
display a platy habit, are either interstitial to or included in
quartz, and show a sub-parallel to random lineation. Rare
hematite crystals are generally interstitial to quartz. The mineral
assemblages are consistent with a sandstone protolith, but no
relict sedimentary textures are preserved.
Olbalbal
Geology
Olbalbal is a fault graben located between
Ngorongoro/Olmoti and Oldupai’s First Fault (Figures 1b,
7G;Supplementary Figure 44), and was formed between 1.3
and 0.6 Ma as a result of regional tilting and faulting events (Hay,
1976; Foster et al., 1997; Mollel and Swisher, 2012). Olbalbal
may be considered as a temporally constrained secondary source
of raw materials and is the present-day drainage sump of the
Oldupai River and the northwestern NVH. Four magmatic
samples recovered in secondary position were analyzed for this
study (Table 1).
Petrography
Sample A1 is a nephelinite and contains nepheline phenocrysts
and lesser amounts of aegirine-augite, hornblende, and
titanite included in a dark-brown groundmass (Table 2)
(Supplementary Section 1.10). The phenocrysts and
groundmass are weakly aligned. SEM-EDS and EPMA
analysis allowed the identification of titanoaugite, wollastonite,
apatite, calcic plagioclase, and Cl-bearing silicates (Figure 6G;
Supplementary Figures 45, 46). This sample can be sourced
to Sadiman and would be categorized as Zaitsev et al.’s (2012)
“Rock type II” based on the presence of wollastonite.
The non-diagnostic mineral assemblages for the three
remaining samples (A2, A5A/B, and A6) hindered satisfactory
classification (Table 2) (Supplementary Section 1.10). In these
samples, oxides are common and together with the presence
of secondary carbonate crystals are, in part, indicative of
seasonal exposure to inundation regimes typical of Olbalbal
(Supplementary Figure 44B).
Sample A2 is an inequigranular, flow-aligned, porphyritic
basalt with plagioclase (20%), opaque crystals (1%), augite (1%),
and olivine (1%) phenocrysts included in a trachytic light-
gray plagioclase-rich groundmass. Plagioclase phenocrysts are
occasionally zoned and have a glomerophyric texture. Olivine
phenocrysts are occasionally altered evidenced by internal cracks
filled with opaque material.
Sample A5A/B is a flow-aligned, porphyritic basalt with
plagioclase (1%) and augite (<1%) phenocrysts included in a
trachytic light-gray plagioclase-rich groundmass. Vesicles are
occasionally filled with secondary micritic carbonate crystals that
precipitated from seasonal standing water rather than having
crystallized from molten-carbonate magma.
Sample A6 was identified as a trachyandesite/basalt from
Olmoti based on the presence of kaersutite (Figures 8E,F;
Supplementary Figure 47) (Mollel, 2002; Mollel et al., 2009).
This sample is vesicular, felty, and contains plagioclase
(1%), kaersutite (1%), augite (<1%), alkali feldspar (<1%),
pyroxene (<1%), ilmenite (<1%), and magnetite (<1%)
microphenocrysts included in a felty light-gray groundmass.
SEM-EDS and EPMA analysis confirmed the presence of
kaersutite, potassium feldspar, pyroxene, ilmenite, and magnetite
(Figure 6H;Supplementary Figures 48, 49).
There are a minimum of four varieties of igneous rocks that
can be found at Olbalbal (Tables 2,3), including phenocryst-
rich nephelinite sourced from Sadiman, two basaltic varieties
with different amounts of plagioclase, and kaersutite-bearing
trachyandesite/basalt sourced from Olmoti.
INTER-OUTCROP COMPARATIVE
ANALYSES OF QUARTZITES AND
META-GRANITES
Quartzites and meta-granites form the most abundant raw
materials in the outcrops described in this study. These
lithologies show variations in modal mineralogy and texture that
may be used to group them into distinct varieties. The following
sections describe the quartzite and meta-granite varieties deemed
archaeologically relevant for sourcing.
Quartzites
From the 16 quartzite varieties, two co-occur at two outcrops
(Tables 2,4):
(1) Variety 8 from Naibor Soit Ndogo is a coarse-grained
fuchsite-bearing quartzite. Similar modal percentages of
quartz, muscovite, fuchsite, rutile, and opaque crystals can
also be found at Naibor Soit Kubwa in Variety 6. The
presence of fuchsite at both outcrops is unique compared
to all sampled outcrops in the Oldupai paleobasin, while the
presence of magnetite is unique to quartzite from Naibor Soit
Kubwa. Samples classified in Variety 6 and 8 fall within our
previously established Raw Material Group Green 1 (Soto
et al., 2020a).
Six other quartzite varieties uniquely occur at an individual
outcrop (Tables 2,4):
(2) Variety 2 is a coarse-grained alkali feldspar-bearing quartzite
from Endonyo Osunyai. The modal percentages of quartz
(∼80%) and alkali feldspar (10–15%) are unique to
this outcrop.
(3) Variety 5 is a coarse- to fine-grained muscovite-rich quartzite
from Naibor Soit Kubwa. The modal percentages of quartz
(70%) and muscovite (∼30%) are unique to this outcrop.
(4) Variety 10 is a medium- to fine-grained quartzite from
Naisiusiu. The polymineralic assemblage including biotite,
Cr-bearing rutile, albite, and tschermakite are unique to
this outcrop.
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Favreau et al. Raw Material Characterization at Oldupai
TABLE 4 | Quartzite varieties.
Source/outcrop Sample ID Grain size Variety Raw material groups (Soto
et al., 2020a)
Endonyo Osunyai Endonyo Osunyai 1 Coarse 1 W3
Endonyo Osunyai 2 Coarse 1 W3
Endonyo Osunyai 4A Coarse 2 GR2
Endonyo Osunyai 4B Coarse 2 GR2
Gol Mountains DDD1 Coarse 3 GR2
PPP1 Medium 4 W3
RRR1 Coarse 4 G1
SSS1 Coarse-medium 4 GR2
Naibor Soit Kubwa Naibor Soit Kubwa 27 Coarse-fine 5 R3
Naibor Soit Kubwa 6 Medium 6 GR1
Naibor Soit Kubwa 32 Coarse-medium 6 GR1
Naibor Soit Kubwa N042 Coarse 7 R3
Naibor Soit Kubwa E039 Coarse 7 W1
Naibor Soit Kubwa S06 Coarse 7 W3
Naibor Soit Kubwa 1 Medium 7 R3
Naibor Soit Kubwa 2 Medium 7 W3
Naibor Soit Kubwa 8 Coarse 7 R3
Naibor Soit Kubwa 11 Coarse 7 W3
Naibor Soit Kubwa 13 Coarse 7 R3
Naibor Soit Kubwa 14 Coarse 7 W2
Naibor Soit Kubwa 24 Coarse-fine 7 W2
Naibor Soit Kubwa 31 Coarse 7 G1
Naibor Soit Kubwa 33 Coarse 7 GR1
Naibor Soit Ndogo Naibor Soit Ndogo 13 Coarse 8 W2
Naibor Soit Ndogo 14 Coarse 8 G1
Naibor Soit Ndogo 6A Coarse 9 GR1
Naibor Soit Ndogo 6B Coarse 9 GR1
Naibor Soit Ndogo 8 Coarse 9 W3
Naibor Soit Ndogo 15 Coarse 9 W3
Naisiusiu Naisiusiu 4 Medium-fine 10 GR2
Naisiusiu 7 Coarse-fine 11 GR1
Naisiusiu 9 Medium 12 W4
Naisiusiu 13 Coarse-medium 12 GR1
Naisiusiu 14 Coarse-fine 12 W3
Oittii Oittii 1A Medium 13 GR2
Oittii 1B Medium 13 GR2
Oittii 4 Coarse-fine 13 GR2
Oittii 3 Coarse-medium 14 W4
Oittii 5A Medium 14 GR2
Oittii 5B Medium 14 GR2
Granite Falls Granite Falls 4A Medium-fine 15 n/a
Granite Falls 4B Medium-fine 15 n/a
Kelogi Kelogi 9 Fine 16 n/a
Refer to Table 2 for sample mineralogy.
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Favreau et al. Raw Material Characterization at Oldupai
FIGURE 9 | (a) Intra-outcrop quartzite varieties in the Oldupai Gorge region. Refer to Figure 1b for outcrop names. Refer to section Quartzites. and Table 4 for
additional details; (b) Intra-outcrop meta-granite varieties in the Oldupai Gorge region. Refer to Figure 1b for outcrop names. Refer to section Meta-Granites and
Table 5 for additional details.
(5) Variety 11 is a coarse- to fine-grained quartzite from
Naisiusiu. The polymineralic assemblage including chlorite,
calcite, and glauconite are unique to this outcrop.
(6) Variety 14 is a coarse- to medium-grained alkali feldspar-
bearing quartzite from Oittii. The modal percentages of
quartz (85%), muscovite (10–15%), and alkali feldspar (∼1–
5%) are unique on a local scale. Similar modal percentages
of quartz, muscovite, and alkali feldspar can also be found in
Variety 3 from the Gol Mountains.
(7) Variety 16 is a fine-grained staurolite-kyanite-bearing
quartzite that was found in secondary position at
Kelogi (Tables 2,4). The presence of staurolite and
kyanite match published descriptions for quartzites
from Endonyo Okule and Naisiusiu (Hay, 1976: Table
6) (Supplementary Table 4). Therefore, it may be
inferred that this sample was transported in recent
times to Kelogi from either Endonyo Okule or Naisiusiu
(Figure 1b).
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Favreau et al. Raw Material Characterization at Oldupai
Although quartzitic outcrops adjacent to Oldupai have similar
mineral facies (Tables 2,4), the results of this comparative
analysis suggest that five outcrops contain six varieties
of quartzites with unique mineral assemblages, and one
pair of outcrops share fuchsitic quartzites (Figure 9a). The
mineralogically defined petrographic varieties do not overlap
with our previously established Raw Material Groups (Table 4)
(cf. Soto et al., 2020a), which highlights the importance of
systematic and multi-scalar characterization of reference
collections to determine the potential source of lithics.
Meta-Granites
All seven intra-outcrop varieties are differentiable from one
another (Tables 2,5):
(1) Variety 1 is a medium-grained meta-monzo-granite from
the Gol Mountains. The presence of rutile allows for
its differentiation from Variety 2 which is from the
same outcrop. The modal percentages of quartz (45%),
alkali feldspar (40%), and the absence of muscovite
and hornblende allow for its differentiation from all
other varieties.
(2) Variety 2 is a medium- to fine-grained meta-quartz-rich
granitoid from the Gol Mountains. The modal percentage of
hornblende (6%) relative to quartz (60%) and alkali feldspar
(20%) allow for its differentiation from all other varieties.
(3) Variety 3 is a medium-to fine-grained meta-quartz-rich
granitoid from the Gol Mountains. The modal percentages
of quartz (70%) and biotite (10%) allow for its differentiation
from all other varieties.
(4) Variety 4 is a medium- to fine-grained granite gneiss from
Granite Falls. The modal percentages of muscovite (5–8%)
allow for its differentiation from all other varieties.
(5) Variety 5 is a medium-grained aegirine-bearing granite
gneiss from Kelogi. The modal percentages of aegirine (20%)
and plagioclase (12–15%) allow for its differentiation from
Variety 6, also from Kelogi, and from all other varieties.
(6) Variety 6 is a medium- to fine-grained granite gneiss from
Kelogi. The polyminerallic assemblage including titanite
and zircon, and the modal percentages of plagioclase
(25%), quartz (25%), and hornblende (20%) allow for its
differentiation from all other varieties.
(7) Variety 7 is a meta-syeno-granite from Naisiusiu. The
modal percentages of opaque crystals (7%), biotite (2%),
and hornblende (1%) allow for its differentiation from all
other varieties.
Despite the fact that meta-granitic outcrops in the greater
Oldupai region have similar mineral facies (Tables 2,5), the
results of this comparative analysis reveal that five outcrops
contain seven varieties with unique mineral assemblages
(Figure 9b).
ARCHAEOLOGICAL APPLICATIONS
While not all known metamorphic, igneous, or sedimentary
sources/outcrops have been characterized in this study
(Figure 1b), inferences may be drawn concerning hominin raw
TABLE 5 | Meta-granite varieties.
Source/outcrop Sample ID Grain size Variety
Gol
Mountains
JJJ1 Medium 1
KKK1 Medium-fine 2
TTT1 Fine 3
UUU1 Medium-fine 3
Granite Falls Granite Falls
1A
Medium-fine 4
Granite Falls
1B
Medium-fine 4
Granite Falls 2 Medium-fine 4
Kelogi Kelogi 1 Medium 5
Kelogi 3 Medium 5
Kelogi 10 Medium-fine 6
Naisiusiu Naisiusiu 3 Medium-fine 7
Refer to Table 2 for sample mineralogy. JJJ1 and KKK1 are from the same outcrop. TTT1
and UUU1 are from the same outcrop. Modes for Kelogi 1 and 3 are based on point counts
instead of visual estimates.
material transport based on available macroscopic descriptions
compared with our mineralogical data. Leakey (1994) noted
the discovery of a single double-edged heavy-duty scraper
on green quartzite from JK W within Bed III’s fine-grained
ferruginous sands. According to tabulated data for Bed II’s
HWK EE and EF-HR lithic assemblages, there are three (55.8 g)
and two (13.2 g) lithics, respectively, manufactured from green
quartzite (McHenry and de la Torre, 2018: Table 5). The green
color of these artifacts most likely stem from the presence of
fuchsite. Fuchsite is only present in quartzites from Naibor Soit
Kubwa and/or Naibor Soit Ndogo (Variety 6/8) (Tables 2,4)
and therefore it may be inferred as the source/s where hominins
procured green quartzite (Figure 10). This inference implies
that fuchsite-bearing quartzitic outcrops were accessible at the
time of hominin site occupation which correlates with basin-
wide paleogeographic trends for Bed II and III (Hay, 1976).
Furthermore, it may be suggested that both Oldowan (HWK
EE) and Acheulean (JK W and EF-HR) tool-making hominins,
possibly of different biological taxa (but see de la Torre and
Mora, 2014; Domínguez-Rodrigo et al., 2014), exploited the
same outcrops at different times for raw materials.
The discovery of hornblende granofels lithologies recovered
in secondary position south of Olongojoo (Figure 1b;
Supplementary Figure 13A) (Table 1) is noteworthy as it
implies that there are unmapped and/or buried granofelsic
outcrops that may grade into the epidote-amphibolite facies in
a similar fashion to Naibor Soit Kubwa (see section Naibor Soit
Kubwa) and Isilale Aratum (Hay, 1976). This finding relates
to Oldupai’s archaeology as gabbroic rocks can metamorphose
into hornblendic granofels (Bucher and Grapes, 2011). This
may imply that the single “altered but unmetamorphosed” (Hay,
1976, p. 185) gabbro artifact recovered from HWK in Lower
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Favreau et al. Raw Material Characterization at Oldupai
FIGURE 10 | Fuchsitic quartzites are unique to Naibor Soit Kubwa and Naibor Soit Ndogo (see Tables 2,3). Therefore, it can be inferred that green quartzite artifacts
from HWK EE (Oldowan) (McHenry and de la Torre, 2018: Table 5), as well as EF-HR and JK W (Acheulean) (Leakey, 1994; McHenry and de la Torre, 2018: Table 5)
were sourced from Naibor Soit Kubwa and/or Naibor Soit Ndogo. Sites after Hay (1976).
Bed II may have been sourced from the Gol Mountains which
are geographically closer to HWK than the Tanzania Craton
(Figures 1a,b).
CONCLUSIONS
In this study, we synthesized existing descriptions with
new petrographic data from several outcrops near Oldupai
Gorge. By characterizing the range and variability of lithic
raw materials that were available to Pleistocene hominins,
we have demonstrated that there are unique mineralogical
identifiers even among similar lithologies. More specifically,
the comparative analyses of quartzites reveal as many as
six distinguishable varieties with unique mineral assemblages,
and two outcrops share fuchsitic quartzites (Variety 6/8). The
identification of these mineralogically defined petrographic
varieties (Table 4) through systematic analysis of our reference
collection confirms that sourcing quartzite lithics from Oldupai
may be best accomplished using a combination of techniques
headlined by geochemical and petrographic testing (Soto
et al., 2020a,b). For example, one quartzite sample recovered
in secondary position at Kelogi has a mineral assemblage
characterized by staurolite and kyanite. This sample’s unique
mineralogy (Figure 1b) matches published data for quartzites
from Endonyo Okule and Naisiusiu (Hay, 1976: Table 6).
The results of the comparative analysis among meta-granites
reveal that five outcrops contain seven unique varieties.
Although this study has been primarily focused on characterizing
metamorphic lithologies, magmatic samples were also collected
in primary positions at Engelosin, and in secondary positions
at Granite Falls, Naisiusiu, and Olbalbal (Figure 1b) (Table 1).
These samples include phonolite, nephelinite, and basaltic
rocks that are all distinguishable from each other based on
mineralogy and texture (Tables 2,3), and those recovered
in secondary position may be sourced to their volcanic
center by referencing previously published mineralogical data
(Supplementary Table 4). Overall, our results suggest the
feasibility of sourcing certain varieties of quartzites, meta-
granites, phonolites, nephelinites, and occasionally, basalts
based on mineralogy. The unique mineralogy that serve to
distinguish raw material sources may be reflected in the
bulk chemical composition of these samples. Archaeological
comparisons to our open-access reference collection can now
be undertaken.
DATA AVAILABILITY STATEMENT
All datasets for this study are included in the article and the
Supplementary Materials, and these can also be found at the
Federated Research Data Repository (https://www.frdr.ca/repo/
handle/doi:10.20383/101.0185).
AUTHOR’S NOTE
A preprint of this article is available with the Open Science
Framework (https://doi.org/10.31219/osf.io/s2vgr).
AUTHOR CONTRIBUTIONS
JF, MS, RN, PB, SC, PD, SH, and JM contributed to the
conception, design, implementation, and funding of this study.
JF, MS, JI, MI, FL, PL, AM, RP, and LT carried out field data
Frontiers in Earth Science | www.frontiersin.org 23 May 2020 | Volume 8 | Article 158
Favreau et al. Raw Material Characterization at Oldupai
collection. JF, MS, RN, CD, and RM analyzed the data. JF, MS,
RN, PD, and JM wrote the manuscript. All authors revised the
manuscript and approved the submitted version.
FUNDING
This work was supported by the Canadian Social Sciences
and Humanities Research Council under its Partnership Grant
Program no. 895-2016-1017.
ACKNOWLEDGMENTS
JF acknowledges that the datasets analyzed for this study and
portions of this manuscript were originally presented in the
form of a Master’s Thesis at the University of Calgary (Favreau,
2019). These data can be accessed through the Federated
Research Data Repository (doi: 10.20383/101.0153) and the Open
Science Framework (doi: 10.31219/osf.io/ap8sh). The Tanzania
Commission for Science and Technology authorized this
work under permit no. 2018-112-NA-2018-36. The Tanzanian
Ministry of Natural Resources and Tourism, through its
Antiquities Division, granted permission to carry out this work
(14/2017/2018). The Ngorongoro Conservation Area allowed
us to enter the conservation area (BE.504/620/01/53). The
export license for the materials presented herein was granted by
both the Antiquities Division (EA.150/297/01: 5/2018/2019) and
the Tanzanian Executive Secretary of the Mining Commission
(00001258). The Stone Tools, Diet, and Sociality project
recognizes the essential contributions of the Maasai community
at Oldupai Gorge who was instrumental to this study. We thank
the reviewers and Associate Editor whose feedback enhanced the
quality of this manuscript.
SUPPLEMENTARY MATERIAL
The Supplementary Material for this article can be found
online at: https://www.frontiersin.org/articles/10.3389/feart.
2020.00158/full#supplementary-material
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Conflict of Interest: The authors declare that the research was conducted in the
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