The Macururé Complex (Sergipano Belt, NE Brazil) in southern Alagoas state: Geology and geochronology

Abstract

The Sergipano Belt is part of the Southern Subprovince of the Borborema Province (NE Brazil) and
separates the Pernambuco-Alagoas Domain from the São Francisco Craton. The Macururé Domain
is the largest unit of the Sergipano Belt and comprises a basement of Paleoproterozoic age (Jirau do
Ponciano Dome) and a supracrustal succession (Macururé Complex). Here we present the results
of field, petrographic and structural work and of geochronological dating conducted in an area in the
southern part of Alagoas state, northeast of the city of São Brás. The lithological associations of the
Macururé Complex include quartzite, schist and banded metasedimentary rocks (metarhythmites).
The main foliation shows a gentle dip to the southwest and is associated with a SW-plunging mineral
lineation. The mineral assemblage muscovite+biotite+garnet±kyanite±staurolite in schist and
metarhythmite indicates medium pressure and temperature conditions (amphibolite facies) typical
of Barrovian metamorphism. U-Pb dating of detrital zircon grains from a quartzite sample yielded
dominantly Tonian ages, showing a large age peak at c. 985 Ma. These zircon grains are thus derived
from sources related to the Cariris Velhos event. The youngest grain has a 206Pb/238U age of 939±36
Ma (2s), which is considered as the maximum age of deposition. Two smaller age populations of c. 2.0
Ga and 1.1 Ga are also present. The most probable provenance of c. 2.0 Ga zircon grains is the nearby
Jirau do Ponciano Dome. The other age group is more enigmatic and could be related to erosion of
A-type rocks formed during local extensional events preceding the Cariris Velhos event.

Full text

Journal of the Geological Survey of Brazil vol 2, no 1, 17-25, April 2019
Journal of the Geological Survey of Brazil
ISS N: 259 5-19 39
https: //doi.org/10.2 9396/jgs b.2019.v2. n1.2
Open acc ess at jgsb.cprm.gov.br
This wor k is licen sed under a Creative Commons Attribution 4.0 Internacional License.
Article Information
Abstract
*Corresponding author
Sérgio P. Neves
E-mail address:
serpane@hotlink.com.br
Keywor ds:
Brasiliano-Pan- African
Orogeny
Barrovian metamorphism
detrital zircons
provenance
Publication type: Research paper
Submit ted: 28 Novem ber 2018
Accept ed: 12 Februar y 2019
Online pu b. 26 Februa ry 2019
Editor: Lu iz C. Silva
The Sergipano Belt is part of the Southern Subprovince of the Borborema Province (N E Brazil) and
separates the Pernambuco- Alagoas Domain from the São Francisco Craton. The Macururé Domain
is the largest unit of the Sergipano Belt and comprises a basement of Paleoproterozoic age (Jirau do
Ponciano Dome) and a supracrustal succession (Macururé Complex). Here we present the results
of field, petrographic and str uctural work and of geochronological dating conducted in an area in the
southern part of Alagoas state, northeast of the city of São Brás. The lithologic al assoc iations of the
Macururé Complex include quartzite, schist and banded metasedimentary rocks (metarhythmites).
The main foliation shows a gentle dip to the southwest and is associated with a SW-plunging mineral
lineation. The mineral assemblage muscovite+biotite+garnet±kyanite±staurolite in schist and
metarhythmite indicates medium pressure and temperature conditions (amphibolite facies) typical
of Barrovian metamorphism. U -Pb dating of detrital zircon grains from a quartzite sample yielded
dominantly Tonian ages, showing a large age peak at c. 98 5 Ma. These zircon grains are thus derived
from sources related to the Cariris Velhos event. The youngest grain has a 20 6Pb/238U age of 939±36
Ma (2s), which is considered as the maximum age of deposition. Two smaller age populations of c. 2.0
Ga and 1.1 Ga are also present. The most probable provenance of c. 2.0 Ga zirc on grains is the nearby
Jirau do Ponc iano Dome. The other age group is more enigmatic and could be related to erosion of
A-type rocks formed during local extensional events preceding the Cariris Velhos event.
The Macururé Complex (Sergipano Belt, NE Brazil) in southern Alagoas state:
Geology and geochronology
Sérgio P. Neves1 , José Maurício Rangel da Silva1 , Olivier Bruguier2
1 Depar tamento d e Geolo gia, Unive rsidad e Federal de Pe rnambu co, 50740- 530, R ecife, Br azil.
2 Géosciences Montpellier, Université de Montpellier, UMR-CNRS 5243, 34095, Montpellier, France.
1. Introduction
The Borborema Province of northeastern Brazil is one of
the several Brasiliano/Pan-African belts formed during the
assemblage of West Gondwana (Van Schmus et al. 2008;
Neves 2015 and references therein). The province is divided
in three subprovinces by the Patos and Pernambuco dextral
shear zone systems (Fig. 1a). The Southern Subprovince
is further subdivided in the Pernambuco-Alagoas (PEAL)
Domain and the Sergipano and Riacho do Pontal belts. The
Sergipano Belt has a triangular shape and is limited by the
PEAL Domain in the north and by the São Francisco Craton
in the south, being separated in western and eastern sectors
by the Tucano-Jatobá rift system (Fig. 1a). The Sergipano
Belt has been divided in several lithostratigraphic domains
(Davison and Santos 1989; D’el-Rey Silva 1999; Oliveira et al.
2006, 2010) (Fig. 1b). The Macururé Domain is the largest unit
and has been the subject of several studies in recent years.
However, most of them have been conducted in the state of
Sergipe (Bueno et al. 2009; Oliveira et al. 2010, 2015a, 2015b,
Conceição et al. 2016; Lisboa et al. 2019). In this paper, we
report the results of geological mapping, petrographic and
structural studies and geochronological dating of an area
in the middle por tion of the Macururé Domain in the state
of Alagoas (Figs. 1b and 1c). With this data, we discuss the
structural style, metamorphic grade, the age of deposition
and the provenance of the metasedimentary rocks in order to
contribute to the understanding of the geological evolution of
the Sergipano Belt.
2. Geological setting
2.1. Sergipano Belt
The Sergipano Belt is dominated by supracrustal
sequences, which have been divided in five lithostratigraphic
domains mainly based on increasing metamorphic grade from
south to north (Davison and Santos 1989; D’el-Rey Silva 1999;
Oliveira et al. 2006, 2010): Estância, Vaza Barris, Macururé,
Poço Redondo-Marancó and Canindé. The southernmost
Estância and Vaza Barris domains are composed of (meta)
sedimentary rocks deformed under subgreenschist (Estância)

18 Neves et al. - JGSB 2019, 2 (1) 17-25
Figure 1 - Geotectonic setting and geographic location of the study area. (a) Sketch showing the subdivision of the Borborema Province in
Northern (NS), Central (CS) and Southern (SS) subprovinces, highlighting the Sergipano (SB) and Riacho do Pontal (RP) belts bordering the
São Francisco Craton. Shear zone systems: PaSZ, Patos; EPSZ, East Pernambuco; WPSZ, West Pernambuco. (b) Simplified geological
map of the area outlined in (a) showing the subdivision of the eastern portion of the Southern Subprovince according to Mendes et al. (2009).
Rectangle shows location of the study area. (c) Geologic al map of the study area. Inset shows its loc ation in the State of Alagoas.
to greenschist (Vaza Barris) facies conditions (D’el-Rey Silva
1999), and, in contrast with the other domains, are not intruded
by granitic plutons.
The Poço Redondo-Marancó and Canindé domains
are located in the northwestern portion of the Sergipano
Belt (Fig. 1b), the latter being separated from the PEAL
Domain by the Jacaré dos Homens contractional shear zone
(Mendes et al. 2009, 2012). Another domain, named Rio
Coruripe, was proposed for the northeastern portion of the
Sergipano Belt (Silva Filho and Torres 2002; Mendes et al.
2009, 2012) but it is debated if it represents the high- grade
counterpart of the Macururé Domain (Oliveira et al. 2006)
or the eastward continuation of the Canindé Domain (Neves
et al. 2016). The Poço Redondo-Marancó Domain consists
of migmatitic orthogneisses and augen gneisses and of a
supracrustal sequence comprising metasedimentary rocks
interlayered with amphibolites, meta-andesites, metadacites,
metarhyolites and serpentinites (Davison and Santos 1989;
Carvalho 2005; Silva Filho 2006). The Canindé Domain
comprises metavolcano-sedimentary sequences and variably
deformed and metamorphosed peridotitic, gabbroic, dioritic
and granitic rocks (Davison and Santos 1989; Mendes et al.
2009; Oliveira et al. 2010). The mesosome of migmatites from
the Poço Redondo-Marancó Domain yielded crystallization
ages ranging from 980 to 960 Ma and the largest augen gneiss
body has crystallization age of 952 ± 2 Ma (Carvalho 2005).
The detrital zircon population in the metasedimentary rocks
from the Canindé Domain is dominated by Neoproterozoic
grains, amongst which the youngest have ages ranging from
708 to 663 Ma (Nascimento 2005; Oliveira et al. 2015a).

19
The Macur uré Complex, Borborema Province
Figure 2 - Lithotypes in the study area. (a) Muscovite quartzite with horizontal foliation. (b) Metarhythmite showing alternating pelitic-rich and
psammitic -rich bands. (c) Muscovite biotite schist with porphyroblasts of staurolite. (d) Boudinage layers of calc-silicate rock in pelitic schist.
The Macururé domain constitutes most of the central
and northern parts of the Sergipano Belt. It consists of
metasedimentary rocks of the Macururé Complex, which
surrounds basement rocks of the Jirau do Ponciano Dome
(Fig. 1b). The Jirau do Ponciano Dome consists of tonalitic to
granodioritic high-grade orthogneisses (Jirau do Ponciano
Complex) interleaved with metavolcano-sedimentary rocks of the
Nicolau- Campo Grande Complex (Mendes et al. 2009, 2012).
The Macururé Complex include quartzites, metapelites and
metarhythmites. This complex was metamorphosed dominantly
under amphibolite facies conditions (Silva et al. 1995), and
intruded by several granitic stocks (Bueno et al. 2009; Oliveira et
al. 2015b; Conceição et al. 2016; Lisboa et al. 2019) during the
Brasiliano Orogeny. Zircon U- Pb dating of ort hogneiss samples of
the Jirau do Ponciano Complex yielded dominant crystallization
ages in the interval 2.04-2.06 Ga (Spalletta and Oliveira 2017).
These ages are similar to crystallization ages of amphibolite and
metarhyolite samples from the Nicolau-Campo Grande Complex
(2.05-2.07 Ga; Lima et al. 2019). U-Pb dating of detrital zircon
grains from metasedimentary rocks of the Macururé Complex
showed age clusters mainly in the intervals 1050-930 Ma and
2100-1900 Ma (Oliveira et al. 2006, 2010, 2015a). The granitoids
emplaced into the Macururé Complex yielded crystallization
ages ranging from 630 to 570 Ma (Bueno et al. 2009; Oliveira et
al. 2015b; Conceição et al. 2016; Lisboa et al. 2019).
2.2. Study area
The study area is situated in the eastern portion of the
Sergipano Belt, northeastward of the city of São Brás, State
of Alagoas (Fig. 1c). Orthogneisses belonging to the Jirau do
Ponciano Dome o ccur in its nor thern por tion. They are represente d
by muscovite-bearing granitic gneisses, with local intercalation
of amphibolite lenses, and by migmatized orthogneisses with
amphibole-bearing mesosome. The lithological associations of
the Macururé Complex include muscovite quartzite (Fig. 2a),
banded metasedimentary rocks (metarhythmites; Fig. 2b) and
mica schist (Fig. 2c). Quartzite occurs at the southern contact of
the orthogneissic basement with the Macururé Complex, forming
the base of the metasedimentary cover, and as map-scale (Fig.
1c) to thin lenses intercalated with the banded metasedimentary
rocks. Pelitic-psammitic metasedimentary rocks are the most
abundant lithologies. The pelitic bands are composed of quartz,
biotite, muscovite and garnet whereas the psammitic layers are
dominated by quartz ± feldspar. The banded appearance gives
place to a more homogeneous texture in fine-to medium-grained
pelitic schists, which show the same mineral assemblage of
the pelitic bands of the metarhythmites. Calc-silicate rocks
composed of quartz, plagioclase, amphibole, epidote and quartz
may occur as thin, centimeter- to decimeter-thick bands in these
rocks (Fig. 2d). A small body of porphyritic granite intrudes the
metasedimentary sequence in the west part of the area.
3. Structure and metamorphism
In the study area, the Macururé Complex shows a relatively
simple geological structure. The centimetric to decimetric
alternating layers of metapelites and metapsammites in the
metarhythmites represent the original bedding (S0) and can
be related to the Tc-Td-Te or Td-Te intervals of classic Bouma
turbidites (Silva et al. 1995). The main foliation is usually
parallel to the bedding and shows low to moderate dip to

20 Neves et al. - JGSB 2019, 2 (1) 17-25
Figure 3 - Structural aspects of the study area. (a) Poles to the main foliation (S2) and their Kamb contours (2 sigma intervals), and mineral
lineations plotted on equal-area (lower hemisphere) projections. The great circle is fitted to the distribution of the foliation poles and the square
indicates its pole (251°, 23°). (b) Intrafolial isoclinal folds. (c) Mica foliation oblique to bedding. (d) Porphyroblasts of kyanite defining a mineral
lineation. (e, f) Kinematic shear criteria. (e) En-echelon quar tz veins. (f ) C’-type shear bands.
the southwest (Fig. 3a). This foliation is interpreted to be of
second generation (S2) because intrafolial, tight to isoclinal
folds defined by micas, so indicating existence of a previous
metamorphic foliation (S1), are locally obser ved (Fig. 3b). In
places where S2 is oblique to S0, its dip is always steeper (Fig.
3c). Mineral lineations, sometimes defined by kyanite, plunge
mainly to the southwest (Figs. 1c, 3a and 3d). Stretching
lineations are only rarely observed and kinematic shear criteria
were only found near the city of São Brás (Fig. 1c). There, the
foliation dips to the northeast and en-echelon quartz veins
(Fig. 3e) and C’-type shear bands (Fig. 3f) indicate top-to-the-
southwest tectonic transport. Poles to S2 define a broad girdle
whose axis plunges 23° to S72°W (Fig. 3a), which coincides
with the orientation of hinge lines of crenulations formed in a
later deformation phase.
In schists and metarhythmites, garnet is ubiquitous
as an accessory mineral phase (Fig. 4a) and centimetric
porphyroblasts of staurolite and kyanite (Figs. 2c and 3d),
sometimes together (Fig. 4b), are common. Syntectonic growth
of kyanite during development of S2 is attested by its orientation
parallel to L2, with no sign of superposition of a previous foliation
(Figs. 3d and 4c). Garnet may show an internal foliation oblique
to the external foliation, indicating early-S2 growth. Staurolite
usually occurs as elongate poikiloblasts with internal foliation
continuous with S2 (Fig. 4d), but in places the internal foliation is
slightly curved, indicating early-S2 growth.

21
The Macur uré Complex, Borborema Province
Figure 4 - Metamorphic aspects of the study area. a) Zoned garnet (Gr t) porphyroblast. (b) Metamorphic assemblage biotite (Bt)-muscovite
(Ms)-kyanite (Ky)-staurolite (St). (c) Elongate porphyroblast of kyanite parallel to the foliation defined by biotite. (d) Elongate poikiloblast of
staurolite with internal foliation (Si) parallel to the external foliation S2 (Se).
4. U-Pb geochronology
Two samples were chosen for the geochronological study,
one from a kyanite-bearing garnet biotite muscovite schist and
one from a muscovite quartzite, but the first did not yield zircon
grains. The analyzed sample (MAC-02) is from a quartzite
collected at coordinates 10°06’52.7”S; 36°49’23.8”W (Fig. 1c).
Zircon grains were separated using conventional techniques.
U-Pb zircon ages were obtained by laser ablation inductively
coupled plasma-mass spectrometry (LA-ICP-MS) at the
Université de Montpellier, France, following the procedure
detailed in Neves et al. (2016).
The U-Pb results are shown in Table 1 and in Fig. 5. Forty-
one grains were analyzed, all of which show oscillatory zoning
and high Th/U ratios (mostly above 0.5) suggestive of derivation
of igneous (or metaigneous) sources (e.g., Kirkland et al. 2015).
Of these, 25 grains yielded discordance < 5% and are the only
discussed. The concordant data define three age groups. The
three populations of zircon grains have similar morphologies,
being dominated by elongate grains with rounded corners
(Fig. 5). The oldest group comprises five analyses with
207Pb/206Pb ages ranging from 1954±28 Ma (2s) to 2046±38
Ma (2s). The second group comprises four analyses that
yielded Late Mesoproterozoic ages around 1100 Ma. The
remaining 16 analyses are of latest Mesoproterozoic to earliest
Neoproterozoic age, showing a large age peak at c. 985 Ma.
The youngest grain has a 206Pb/238U age of 939±36 Ma (2s),
which is considered as the maximum age for deposition.
5. Discussion
The dominant flat-lying foliation in the study area suggests
development associated with thrust tectonics. The absence
of mylonitic belts and the rarity of stretching lineations
indicates distributed non-coaxial deformation, without strain
localization. The local presence of shear criteria indicating
top-to-the-southwest tectonic transport (Figs. 3e, f) agrees
with the he overall vergence of the Sergipano Belt towards
the São Francisco Craton (Brito Neves et al. 1977; Jardim de
Sá et al. 1992; D’el-Rey Silva 1999; Oliveira et al. 2010). In
this context, the southwestward dip of the main foliation in
the study area is attributed to later folding. In places where S2
is oblique to S0, its dip is always steeper (Fig. 3c), indicating
that the study area may be located in the normal limb of an
inverted macroscopic fold with northeastern vergence. This
inference is consistent with location of the study area south
of the Jirau do Ponciano Dome, which is shown on regional
maps as an inverted antiform (Mendes et al. 2009, 2012;
Lima et al. 2019).
Oliveira et al. (2010) proposed a time gap between S1
and S2 based on obser vations in the central portion of the
Macururé Domain. In contrast, S1 and S2 are here interpreted
as resulting from progressive deformation, giving the absence
of any metamorphic discontinuity, as previously discussed
by Silva et al. (1995). The mineral assemblage muscovite+b
iotite+garnet±kyanite±staurolite (Fig. 4b) indicates medium
pressure and temperature conditions (amphibolite facies)
typical of Barrovian metamorphism.

22 Neves et al. - JGSB 2019, 2 (1) 17-25
Table 1. U-Pb LA-ICP-MS analyses of zircon grains from muscovite quar tzite (sample MAC- 02) of the Macururé Complex.
Analysis Pb* (pp m) Th (pp m) U (ppm) Th/ U 208Pb/
206Pb
207Pb/
206Pb ± (1s) 207Pb/
235U ± (1s) 206Pb /
238U ± (1s) Rho
Apparent
206Pb /
238U
± (1s)
ages (Ma)
207Pb/
206Pb
± (1s) Err
R8 % Err 7/6 % Conc.(%)
#1 16.6 113 . 0 90.3 1. 25 0.323 0.089 3 0.0009 1.8104 0.0240 0 .147 0 0.0 013 0.66 884 71 411 19 0.9 1.0 62.6
#2 25.4 113 .1 150. 3 0.75 0. 2 11 0.0763 0.0008 1.5783 0.0222 0.14 99 0 .0 013 0.62 901 711 0 4 22 0.9 1.1 81.6
#3 62.5 300 .7 328.8 0.91 0.2 75 0.0 719 0.0007 1.574 0 0.0237 0.1 5 88 0 .0 017 0.73 950 10 983 21 1 .1 1.0 9 6.7
#4 52.4 129. 8 162.9 0.80 0 .15 0 0.1 23 9 0.0010 5.05 65 0.0557 0.2959 0.0023 0.70 16 71 11 2014 14 0.8 0.8 83.0
#5 84.7 13 6.7 223.6 0.61 0 .174 0 .119 8 0. 0010 5.6611 0.06 12 0.3426 0.0 025 0.66 189 9 12 1954 14 0 .7 0.8 97. 2
#6 23.2 106. 5 112 .9 0.9 4 0.298 0.0724 0.0006 1.6832 0.0 242 0.1 68 6 0. 0019 0.78 10 05 10 997 18 1.1 0.9 100.8
#7 68.8 192.7 398.3 0.4 8 0.1 57 0 .0 749 0.0007 1.64 00 0 .0197 0 .15 8 8 0.0 012 0.62 950 7106 6 19 0.7 0.9 89.2
#8 96.2 196 .3 246. 6 0.80 0.227 0.121 4 0.0009 5.7955 0. 0918 0.3 461 0.00 48 0.87 1916 23 197 7 14 1.4 0.8 96.9
#9 33.4 138. 5 151. 8 0.91 0. 316 0.0730 0.0008 1.724 6 0.0343 0 .171 4 0.0028 0.82 1020 15 1 013 23 1.6 1.1 10 0.7
#10 82.6 372.0 445.2 0.84 0. 256 0.0724 0.0006 1.5 974 0.0233 0 .16 0 0 0.0020 0.8 5 957 11 997 16 1. 2 0.8 96.0
#11 4.0 15 .0 20.2 0 .74 0.24 5 0.0738 0. 0014 1. 7337 0. 0427 0 .170 3 0.0028 0.6 6 1014 15 1037 37 1.6 1. 8 9 7. 8
#12 45.4 10 6 .1 116 . 4 0.91 0.223 0 .12 19 0. 0010 5.806 0 0.0688 0.3 453 0.0028 0.70 1912 14 19 85 15 0.8 0.9 96.3
#13 33.5 101. 4 18 2.1 0.5 6 0.17 4 0.0722 0.0007 1.678 5 0.0186 0 .1 68 6 0. 0010 0.54 10 05 6991 19 0.6 0. 9 101.4
#14 117. 3 189 .3 533.3 0.35 0 .16 4 0 .12 74 0. 0010 3.3639 0.054 0 0.1 915 0.0 026 0.86 113 0 14 2062 14 1. 4 0.8 54.8
#15 2 7.5 13 4.0 162.3 0.8 3 0.248 0.076 9 0.0006 1.59 48 0. 0140 0 .15 0 4 0.0004 0.30 903 21119 17 0.3 0.8 80 .7
#16 81.5 260. 2 4 67. 0 0.56 0 .17 6 0. 074 5 0.0007 1.6524 0 .0159 0 .16 0 9 0.0006 0.39 962 31055 18 0.4 0.9 91.2
#17 21.0 1 5 3.1 14 4.7 1.0 6 0 .19 6 0. 0816 0.0008 1.45 04 0.0260 0 .12 9 0 0.0 019 0.83 782 11 12 35 20 1.5 1. 0 63.3
#18 101.4 14 8.4 42 9.0 0.35 0 .119 0 .12 91 0. 00 17 4.9529 0.1 66 4 0. 2782 0.0086 0.92 1582 43 20 86 23 3.1 1. 3 75.8
#19 74. 6 516 .1 435.0 1.1 9 0.299 0.07 87 0.0006 1.5492 0.0159 0 .142 8 0.0009 0.64 861 511 64 15 0 .7 0.8 73.9
#20 7.1 25.3 3 7.1 0.68 0.222 0.0720 0.0006 1.6954 0.0210 0.170 7 0.0 016 0 .76 1016 9986 16 0.9 0.8 103.0
#21 292 .7 552.6 113 0 .6 0.49 0 .1 66 0 .12 3 9 0.0013 3 .9726 0.0 607 0.2326 0.0027 0.7 5 1348 14 2 013 18 1.1 1. 0 67. 0
#22 72.3 415 .9 411 .3 1. 01 0.309 0. 0736 0.0006 1.60 45 0.0206 0 .15 8 0 0.0 015 0.75 946 810 32 17 1.0 0.9 91.7
#23 13.5 51 .4 71. 6 0.72 0.226 0. 0723 0.0009 1.68 31 0.0281 0.16 9 0 0.0 018 0.65 100 6 10 993 26 1 .1 1.3 101. 3
#24 23.8 120 .9 140 .6 0.86 0. 228 0.0764 0.0009 1.64 67 0.0 198 0 .15 62 0.0007 0.37 936 4110 7 22 0.4 1.1 8 4.6
#25 36.6 55.2 101. 6 0.54 0 .17 0 0.12 6 2 0.0 013 6.34 42 0.0937 0.3 645 0.0038 0.70 20 03 18 2046 19 1.0 1.1 9 7. 9
#26 24.0 83.6 146 .6 0.57 0 .19 3 0.0709 0.0008 1.5 332 0.0 356 0.1 5 69 0.0 032 0.89 939 18 954 22 2.1 1 .1 98.5
#27 52.2 33 8.7 206.0 1.6 4 0 .171 0.1267 0. 00 11 4.0633 0.0526 0.2326 0.0 022 0.73 13 48 11 2052 16 0.9 0.9 65 .7
#28 12.7 15 .7 65.8 0.24 0 .0 74 0.0756 0.0008 1.9580 0.0328 0.18 7 8 0.0024 0.78 110 9 13 108 5 21 1.3 1.1 102.2
#29 63.3 139. 7 166.3 0. 84 0. 241 0 .12 3 3 0.0010 5 .8421 0.0 634 0.3435 0.0025 0.67 19 04 12 2005 14 0.7 0. 8 94.9
#30 102.3 98.4 276.5 0.36 0 .13 6 0 .12 61 0.0 010 6.2642 0.0674 0.3602 0.0026 0.68 1983 12 204 5 14 0.7 0.8 97. 0
#31 124. 5 185 .4 343.5 0.54 0 .15 6 0 .12 0 9 0.0010 5.6242 0.0642 0 . 33 74 0.0026 0.68 18 74 13 196 9 15 0.8 0.8 95.2
#32 100. 8 585.6 422.4 1. 39 0 .4 11 0.0782 0.0006 2.0017 0.0217 0.18 57 0. 0014 0. 69 1098 81151 15 0.8 0.8 95.4
#33 45.4 305.2 2 2 7.7 1. 34 0 .4 11 0.0 715 0.0006 1.5559 0.0244 0.1579 0.0020 0.82 945 11 971 18 1.3 0.9 9 7. 4
#34 85.9 238.3 4 97. 0 0.48 0 .15 2 0.0734 0 .0 013 1.6 59 9 0.0337 0 .16 41 0. 0016 0.49 979 9102 4 35 1.0 1.8 95.6
#35 53.5 374 .1 242.9 1. 54 0.4 64 0. 0714 0.0007 1.655 6 0.0223 0.1 6 83 0 .0016 0.7 2 1003 9968 19 1.0 0.9 103 .6
#36 16.3 50.3 9 1.1 0.5 5 0.17 2 0.0725 0.0007 1.68 92 0.0257 0 .16 8 9 0.0 019 0.74 10 06 10 1001 21 1.1 1.0 100.5
#37 102.3 661. 4 561.6 1.1 8 0. 371 0.0737 0.0008 1.68 28 0.0275 0.1 6 57 0.0021 0.76 988 11 10 32 21 1.2 1 .1 95.8
#38 116 .5 6 05.0 642.9 0. 94 0.285 0.0722 0.0006 1.6 05 0 0.0230 0.1611 0.0019 0.83 963 11 9 93 16 1.2 0.8 9 7. 0
#39 121.9 102.1 345.2 0.30 0.10 8 0 .12 73 0 .0 0 11 6.0172 0.0704 0.3427 0.0026 0. 66 190 0 13 2062 15 0.8 0.9 92.2
#40 15.6 41.5 75. 3 0.55 0 .16 9 0.0770 0.0009 2.0234 0.0297 0.1906 0.0018 0.65 112 5 10 112 1 22 1.0 1.1 10 0.3
#41 16 .2 42.8 78. 0 0.55 0.167 0.0761 0.0008 1.9 662 0.029 5 0.1 87 5 0.0021 0.74 11 0 8 11 10 97 20 1.1 1.0 1 01.0

23
The Macur uré Complex, Borborema Province
Figure 5 - Probability and Concordia plots for LA-ICP-MS zircon analyses from sample MAC- 02 and representative backscattered electron
(BSE) images of analyzed grains.
The detrital zircon ages of sample MAC-02 (Fig. 5) are
similar to other dated samples from the Macururé Complex
(Van Schmus et al. 2011; Oliveira et al. 2006, 2010, 2015a),
which revealed no post-Tonian zircon grains (Fig. 6). The
dominant latest Mesoproterozoic to early Neoproterozoic
ages show that the main sources of the detritus were formed
during the Cariris Velhos event (Brito Neves et al. 1995). This
event was first documented in the Alto Pajeú Domain of the
Central Subprovince (Brito Neves et al. 1996; Santos et al.
2010; Van Schmus et al. 2011; Guimarães et al. 2012) but
was later recognized in the PEAL Domain (Brito et al. 2008;
Cruz et al. 2014; Da Silva Filho et al. 2014), Marancó-Poço
Redondo Domain (Carvalho 2005; Oliveira et al. 2010), and
Riacho do Pontal Belt (Caxito et al. 2014). Although the nature
of the Cariris Velhos event (if orogenic or extensional) is still
debated, the dominance of bimodal metavolcanic rocks and
of metagranitoids with A-type signature favors an intraplate
origin for the magmatism (Neves 2003; Guimarães et al.
2011, 2012, 2016). Given the wide distribution of the Cariris
Velhos-related rocks, it is not possible to ascertain if zircon
grains of the dominant age group were sourced from proximal
rocks (Marancó-Poço Redondo Domain) or had more distal
provenance. The absence of zircon grains younger than c. 900
Ma in our and in previously analyzed samples could indicate
that deposition of the Macururé Complex occurred at the end
or shortly afterward the Cariris Velhos event. Alternatively, it
may simply be that younger sources were either not available
for erosion at the time of deposition or were not present along
the drainage system.
The most obvious source for zircon grains in the age
interval 1.95-2.05 Ga is the Jirau do Ponciano Dome,
which shows a similar age range (Spalletta and Oliveira

24 Neves et al. - JGSB 2019, 2 (1) 17-25
2017; Lima et al. 2019), although it is somewhat surprising
the comparatively small number of analyses in this age
range given the proximity of available source rocks. The
provenance of zircon grains with ages around 1.1 Ga (Fig.
5) is more enigmatic. The age of 1091±13 Ma recorded in
a metavolcanic rock from the Riacho Gravatá Complex of
the Alto Pajeú Domain (Guimarães et al. 2012) is so far the
only one documented in central and southern Borborema
Province. Guimarães et al. (2012) interpreted this age as
related to an early stage of rifting preceding the Cariris
Velhos event. Similarly, detrital zircon grains from the
Sopa-Brumadinho Formation of the Espinhaço Supergroup
falls within the interval between 1080±16 and 1240±20 Ma
(Chemale Jr. et al. 2012). They are tentatively interpreted
as resulting from erosion of A-type source rocks during
the initial rifting stage corresponding to deposition of the
basal units of the Upper Espinhaço Group (Chemale Jr. et
al. 2012). Therefore, it is possible that the c. 1.1 Ga zircon
population records localized extensional events at the late
Mesoproterozoic in the Borborema Province and/or São
Francisco Craton.
6. Conclusion
The Macururé Domain in southern Alagoas state is
constituted by Paleoproterozoic orthogneisses that outcrop
in the northern part of the study area and by quar tzite,
metarhythmite and micaschist, which are the dominant
lithotypes. The southwestern dipping flat-lying foliation
was developed under amphibolite facies conditions, with
the paragenesis muscovite+biotite+garnet±kyanite±stauro
lite indicating medium P-T (Barrovian) metamorphism. U-Pb
analyses of detrital zircon grains point to the dominance of
early Tonian rocks (1.0 to 0.94 Ga) as the main sources of
the sediments, with a smaller contribution of Paleoproterozoic
(c. 2.0 Ga) and Late Mesoproterozoic (c. 1.1 Ga) sources.
Figure 6 - Cumulative probability density distribution diagram of U-Pb detrital zircon ages from metasedimentary rocks of the Macururé
Complex. Sources of data: MAC-02, this study; FS-89 and FS-68, Oliveira et al. (2015); 92-09, Van Schmus et al. (2011).

25
The Macur uré Complex, Borborema Province
Acknowledgments
This work was supported through funding from the Brazilian
agency Conselho Nacional de Desenvolvimento Científico e
Tecnológico (CNPq; grant 472582/2011-9). Detailed comments
by Mahyra Tedeschi helped to improve the paper.
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