Precambrian Research 149 (2006) 197–216

Timing of crust formation, deposition of supracrustal sequences, and Transamazonian and Brasiliano in the East Pernambuco belt (Borborema Province, NE ): Implications for western assembly Sergio´ P. a,∗, Olivier Bruguier b, Alain Vauchez c, Delphine Bosch c, Jose´ Maur´ıcio Rangel da Silva a, Gorki Mariano a a Departamento de Geologia, Universidade Federal de Pernambuco, 50740-530 Recife, Brazil b ISTEEM, Service ICP-MS, Universit´e de Montpellier II, 34095 Montpellier, France c Laboratoire de Tectonophysique, Universit´e de Montpellier II, 34095 Montpellier, France Received 21 July 2005; received in revised form 10 January 2006; accepted 21 June 2006

Abstract The structural feature of the central domain of Borborema Province (NE Brazil) is a network of dextral and sinistral shear zones. These shear zones rework an older, regionally developed, flat-lying foliation in orthogneisses and supracrustal belts, which in the East Pernambuco belt was formed under amphibolite facies conditions. This study reports LA-ICP-MS U–Pb zircon ages of metaigneous and metasedimentary rocks aiming to constraint the pre-transcurrent tectonothermal evolution in the Eastern Pernambuco domain. Ages of 2125 ± 7 and 2044 ± 5 Ma in a mafic layer of banded orthogneiss are interpreted as the age of the protolith of the orthogneiss and of high-grade Transamazonian metamorphism, respectively. The latter age is consistent with the occurrence of low Th/U, metamorphic zircon xenocrysts, dated at 2041 ± 15 Ma, in the leucosome of a migmatitic paragneiss. A granitic orthogneiss dated at 1991 ± 5 Ma reflects late to post-Transamazonian magmatic event. A similar age (1972 ± 8 Ma) was found in rounded zircon grains from a leucocratic layer of banded orthogneiss. Ages of detrital zircons in a paragneiss sample indicate derivation from sources with ages varying from the Archean to Neoproterozoic, with peak ages at ca. 2220, 2060–1940, 1200–1150 and 870–760 Ma. Detrital zircons constrain the deposition of the supracrustal sequence to be younger than 665 Ma. Magmatic zircons with the age of 626 ± 15 Ma are found in the leucosome of a migmatitic paragneiss and constrain the age of the Brasiliano high-temperature metamorphism. A lower intercept age of 619 ± 36 Ma from a deformed granodiorite dated at 2097 ± 5 Ma and the crystallization age of 625 ± 24 Ma of the felsic layer of banded orthogneiss also confirm the late Neoproterozoic metamorphism. These results show that the present fabric in basement and supracrustal rocks was produced during the Brasiliano . Paleoproterozoic ages reported in this study are similar to those found in other sectors of the Borborema Province, the Cameroon and Nigeria provinces, and the Sao˜ Francisco/Congo . They show the importance of the Transamazonian/Eburnean event and suggest that these tectonic units may have been part of a larger, single continental landmass. Likewise, similarities in post- Transamazonian metamorphic and magmatic events in the Borborema, Nigeria and Cameroon provinces suggest that they shared a common evolution and remained in close proximity until the opening of the . © 2006 Elsevier B.V. All rights reserved.

Keywords: Laser ablation ICP-MS; Zircon U–Pb geochronology; Neoproterozoic belts; Transamazonian orogeny; Brasiliano orogeny

∗ Corresponding author. Tel.: +55 81 2126 8240; fax: +55 81 2126 8236. E-mail address: [email protected] (S.P. Neves).

0301-9268/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.precamres.2006.06.005 198 S.P. Neves et al. / Precambrian Research 149 (2006) 197–216

1. Introduction Pajeu´ belt, Alto Moxoto´ belt and East Pernambuco belt (Fig. 1). There is broad consensus that most of western To improve knowledge and address the controversial Gondwana was already formed by 600 Ma. Continen- points above, zircon grains from samples from the East tal reconstructions for this period (e.g., Caby et al., Pernambuco belt were dated by laser ablation inductively 1991; Castaing et al., 1994; Trompette, 1997) show that coupled plasma-mass spectrometry (LA-ICP-MS). The the Brasiliano/Pan-African Borborema, Cameroon and aim of this study is threefold: (1) constrain the timing Nigeria provinces occupied a central position in relation of magmatic and metamorphic events and of deposition to the and West Africa , to the west, of supracrustal sequences, (2) compare its geological the Sao˜ Francisco/, to the , and the evolution with other regions in northeastern Brazil and Saharan metacraton (Abdelsalam et al., 2002), to the east with the Pan-African belts of Nigeria and Cameroon, and (Fig. 1). In the lack of paleomagnetic data, understand- (3) assess how these domains and surrounding cratons ing how and when this configuration was reached rely on pulled together to make up western Gondwana. geological and geochronological grounds. Knowledge of the tectonothermal history of the late Neoproterozoic 2. Geological setting belts is thus essential to evaluate possible correlations between adjacent (within individual provinces) and dis- 2.1. Regional geology tant (transcontinental) units and, therefore, to provide insights into the dynamics of amalgamation of western The Borborema Province is characterized by a com- Gondwana. plex network of large transcurrent shear zones (Vauchez The Precambrian crustal evolution of the Borborema et al., 1995; Fig. 1). In the central domain, a linked system Province has been much debated in recent years. Resolv- of E–W- to ENE–WSW-striking dextral and NNE–SSW- ing some critical pending issues is necessary to elabo- to NE–SW-striking sinistral shear zones is spatially rate continental reconstructions for the Neoproterozoic. associated with abundant granitic and syenitic plutons In the central domain, comprised between the Patos (Fig. 1B; Vauchez and Egydio-Silva, 1992; Guimaraes˜ and Pernambuco shear zone systems (Fig. 1), the most and Da Silva Filho, 1998; Ferreira et al., 1998; Neves and controversial issues are (1) the existence of a contrac- Mariano, 1999; Neves et al., 2000; Silva and Mariano, tional event in the early Neoproterozoic (Cariris Vel- 2000). A former shallow-dipping regional foliation is hos orogeny, ∼1 Ga; Brito Neves et al., 1995), and preserved in orthogneisses and metasediments outcrop- (2) whether or not terranes accretion took place dur- ping between the strike slip-related steeply dipping to ing this proposed orogeny. The suggestion of an early vertical mylonitic zones. The metamorphic grade under Neoproterozoic orogeny resulted from the discovery of which this foliation was developed differs between the 1000–900 Ma-old intermediate to felsic metavolcanic Cachoeirinha belt and the Alto Pajeu,´ Alto Moxoto´ and rocks and orthogneisses in the Alto Pajeu´ belt (Fig. 1; East Pernambuco belts. The Cachoeirinha belt consists Brito Neves et al., 1995; Van Schmus et al., 1995; of greenschist facies metapelites, metagreywackes and Kozuch et al., 1997; Brito Neves et al., 2000, 2001a; bimodal metavolcanics (Bittar and Campos Neto, 2000; Kozuch, 2003). Peraluminous orthogneisses intercalated Kozuch, 2003; Medeiros, 2004) deformed at relatively in the supracrustal sequence were interpreted as syncol- high pressures (6–9 kbar; Sial, 1993; Caby and Sial, lisional granites. Santos and Medeiros (1999) proposed 1997). Its low metamorphic grade stands in contrast with that the Alto Pajeu´ belt is one of four tectonostrati- that of the other three belts, which were regionally heated graphic terranes that amalgamated during the Cariris above 500 ◦C under low- to medium-pressures metamor- Velhos and Brasiliano to constitute the cen- phic conditions (Vauchez and Egydio-Silva, 1992; Bittar tral domain. Several authors (Mariano et al., 2001; and Campos Neto, 2000; Leite et al., 2000a; Neves et al., Guimaraes˜ and Brito Neves, 2004; Neves, 2003 and ref- 2000). erences therein) have, however, questioned the existence Orthogneiss complexes underlie large areas of the of the Cariris Velhos orogeny and the terrane accre- Alto Pajeu,´ Alto Moxoto´ and East Pernambuco belts. tion model, suggesting, instead, continuity between the They yielded U–Pb and Pb–Pb evaporation ages mostly proposed terranes since the Paleoproterozoic Transama- varying from 2.2 to 2.0 Ga (Santos, 1995; Van Schmus zonian orogeny. Therefore, in this paper, the following et al., 1995; Leite et al., 2000b; Brito Neves et al., non-genetic terms will be used to describe supracrustal 2001b; Melo et al., 2002; Kozuch, 2003; Neves et al., successions and orthogneisses occurring from west to 2004; Santos et al., 2004a), and Sm–Nd data indicate the east in the central domain: Cachoeirinha belt, Alto existence of Archean protoliths for some of these Pale- S.P. Neves et al. / Precambrian Research 149 (2006) 197–216 199

Fig. 1. (A) –Africa fit showing cratons and Neoproterozoic provinces of western Gondwana, and sketch highlighting main shear zones in Borborema Province. (B) Schematic geological map of eastern Borborema Province showing location of the studied area in the East Pernambuco belt (EPB) of central domain. Dashed lines highlight boundaries between the central and northern domains, and between the Cachoeirinha (CB), Alto Pajeu´ (APB) and Alto Moxoto´ (AMB) belts. PaSZ, Patos Shear Zone system; EPSZ, East Pernambuco Shear Zone system; WPSZ, West Pernambuco Shear Zone system. oproterozoic orthogneisses (Van Schmus et al., 1995; new age determinations indicate a younger depositional Brito Neves et al., 2001b; Melo et al., 2002). Domi- age (660–620 Ma; Kozuch, 2003; Medeiros, 2004). In nance of Paleoproterozoic to Archean Sm–Nd model these two belts, Sm–Nd ages range from 1.8 to 1.2 Ga ages in granitic and syenitic plutons (Ferreira et al., 1998; (Brito Neves et al., 2001a; Kozuch, 2003; Archanjo and Mariano et al., 2001; Guimaraes˜ et al., 2004) suggests Fetter, 2004). The oldest Nd model ages suggest that that Paleoproterozoic to Archean basement constitute Paleoproterozoic or older sources provided important most of the central domain. contribution for detritus that filled their precursor sed- In the Alto Pajeu´ belt, metavolcanic rocks have U–Pb imentary basins. In the Cachoeirinha belt, this inference zircon ages mainly comprised between 1000 and 970 Ma is further supported by the occurrence of zircons with (Brito Neves et al., 1995; Van Schmus et al., 1995; ages up to 3278 Ma in a quartzite sample (Silva et al., Kozuch et al., 1997; Brito Neves et al., 2000; Kozuch, 1997) and of Paleoproterozoic zircons in a metarhyolite 2003). Van Schmus et al. (1995) and Kozuch et al. (1997) (Kozuch, 2003). The Sertaniaˆ metasedimentary complex report U–Pb ages for metavolcanic rocks in the Cachoeir- in the Alto Moxoto´ belt yielded zircon grains with ages inha belt in the interval 810–720 Ma. Refinement of around 2.0 Ga (Santos et al., 2004a) and Sm–Nd ages these data due to the presence of inherited zircons and varying from 2.0 to 3.0 Ga (Brito Neves et al., 2001b). 200 S.P. Neves et al. / Precambrian Research 149 (2006) 197–216

These data indicate its provenance mainly from Pale- mation. A deformed epidote-bearing biotite granodior- oproterozoic and Archean sources, but only places an ite (Alcantil pluton; Fig. 2) displays a flat-lying mag- upper bound on the age of deposition. The age of depo- matic/gneissic foliation crosscut by subvertical shear sition of supracrustal sequences in the East Pernambuco bands. This pluton was previously regarded as a Neo- belt is still unknown. proterozoic intrusion emplaced during the top-to-the- northwest tectonics (Neves et al., 2005). However, data 2.2. Study area acquired in the present study favor its intrusion during the Paleoproterozoic, followed by solid-state deforma- The study area is located in the northwestern part tion during the Brasiliano orogeny (see below). Two of the East Pernambuco belt (Fig. 1). It comprises plutons partially outcrop in the southern part of the study banded orthogneisses, granitic augen gneisses, metased- area (Fig. 2). The ca. 585 Ma-old, syenitic Toritama plu- imentary rocks and igneous intrusions (Fig. 2). Banded ton (Guimaraes˜ and Da Silva Filho, 1998) is interpreted orthogneisses are characterized by alternating bands of as early kinematic with respect to strike-slip shearing dioritic and granitic compositions. Zircon U–Pb dat- (Neves et al., 2000). The Santa Cruz do Capibaribe plu- ing from a monzodioritic orthogneiss and a granitic ton is a composite intrusion containing gabbronorites augen gneiss (Taquaritinga orthogneiss) in the southern and diorites in the core and monzonites at the margins, part of the study area yielded ages of 1974 ± 32 and displaying only local solid-state deformation. 1521 ± 6 Ma, respectively (Sa´ et al., 2002). In the geological map of the state of Pernambuco 3. Studied samples (Gomes, 2001), Surubim and Vertentes complexes are recognized as two distinct supracrustal units, mainly Samples for this study represent the main lithological based on the occurrence of metavolcanic rocks in the units and key relations between age and deformation in latter. Metavolcanic rocks were not identified by us in the study area. Six samples weighting 8–12 kg each were the study area nor in other localities of the East Pernam- collected from four localities (Fig. 2B). Samples SCC1A buco belt. Metasedimentary rocks are indistinguishable and SCC1B are, respectively, mafic and felsic layers in terms of rock association, structure or metamorphic of banded orthogneiss. SCC1A is a medium-grained, grade between the Surubim and Vertentes complexes. dark-colored biotite amphibole gneiss with quartz mon- Furthermore, our mapping shows that basement gneisses zodioritic composition. SCC1B is a medium-grained, were misinterpreted as belonging to the Vertentes com- leucocratic granitic gneiss containing less than 10% plex. Therefore, this complex is not considered here biotite. The gneissic banding dips 36◦ towards N104◦E as a valid tectonostratigraphic unit. In consequence, and a strong stretching lineation plunging gently to metasedimentary rocks in the study are attributed to the northeast (21◦, N47◦E) is present in both lithologies. Surubim complex. The main lithotypes are biotite gneiss, Sample SCC9 is a medium to coarse-grained sillimanite biotite schist, quartz-feldspar paragneiss, quartzite and biotite paragneiss containing garnet porphyroblasts up marble, locally with small lenses of para-amphibolite to 1 cm in diameter. Sample SCC12 is the leucosome of and calc-silicate rock. Sillimanite and garnet are ubiqui- a migmatitic paragneiss, and SCC2 is a granitic gneiss. tous accessory phases, which together with local migma- Since contact relationships are not exposed, it is not pos- tization attest high-temperature metamorphism. sible to determine whether the granitic gneiss is a sheet From the structural point of view, the study area intercalated in metasedimentary sequence or whether it is characterized by flat-lying gneissic foliation in underlies it. Quartz ribbons in sample SCC2 attest strong orthogneisses and supracrustal rocks. This early fabric is solid-state deformation and define a lineation plunging deformed by recumbent to upright folds and transcurrent 7◦, N150◦E. Sample SSC5 is from the Alcantil pluton, shear zones (Neves et al., 2005). Stretching lineations showing foliation dipping 36◦ towards N24◦E. associated with the flat-lying foliation have ESE–WNW trend in supracrustal rocks and NE–SW trend in 4. Analytical techniques banded orthogneiss and Taquaritinga orthogneiss. In the metasedimentary sequence, numerous kinematic indica- Zircons were separated using conventional tech- tors showing a top-to-the-west/northwest sense of shear niques. After crushing and sieving of the powdered sam- denote a well-developed non-coaxial deformation. These ples, heavy minerals were concentrated by panning and oblique lineations were interpreted (Neves et al., 2005)as then by heavy liquids. The heavy mineral concentrates the result of extension oblique to the transport direction were subsequently processed by magnetic separation in the deeper orthogneisses during progressive defor- using a Frantz separator. Zircon grains were hand picked S.P. Neves et al. / Precambrian Research 149 (2006) 197–216 201

Fig. 2. (A) Simplified geological map of the East Pernambuco belt showing location of studied area. Modified from Neves and Mariano (1999), Neves et al. (2000) and Gomes (2001). (B) Geological map of the studied area (modified from Neves et al., 2005) showing location of samples analysed by LA-ICP-MS, and existing TIMS U–Pb ages (Sa´ et al., 2002). from the non-magnetic fraction at 1.5 A intensity and 1◦ standard material (G91500; Wiedenbeck et al., 1995) or 2◦ side tilt (Samples SCC1A and SCC9), 2◦ side tilt and polished to about half of their thickness. Internal (samples SCC1B and SCC2), and 4◦ side tilt (samples structure and morphology were subsequently observed SCC5 and SCC12). The grains were then mounted on by Scanning Electron Microscopy (SEM) using a JEOL adhesive tape, enclosed in epoxy resin with chips of a 1200 EX II operating at 120 kV.After BSE imaging, car- 202 S.P. Neves et al. / Precambrian Research 149 (2006) 197–216 bon coating was removed by using alcohol and the resin Inter-element fractionation for Pb and U are much more grain mount was subsequently slightly repolished to get sensitive to analytical conditions and a bias factor was rid of any residual carbon which can potentially con- thus calculated using the four standard measurements tain significant amount of 204Pb (see Hirata and Nesbitt, bracketing each five unknowns. These four measure- 1995). The mount was then cleaned in ultra-pure MQ ments were then averaged to calculate a U–Pb bias factor water and dried before its introduction in the ablation and its associated error, which were added in quadra- cell. ture to the individual error measured on each 206Pb/238U Data were acquired at the University of Montpel- unknown. This typically resulted in a 2–5% precision lier II using a 1991 vintage VG Plasmaquad II turbo (1σ R.S.D.%) after all corrections have been made (see ICP-MS coupled with a Geolas (Microlas) automated Table 1). Ages quoted below were calculated using the platform housing a 193 nm Compex 102 laser from Isoplot program of Ludwig (2000). LambdaPhysik. Analyses were conducted using an in- house modified ablation cell of ca. 5 cm3 which resulted 5. Zircon morphology and internal structure in a shorter washout time and an improved sensitivity compared to the initial larger ablation cell (ca. 30 cm3). Zircon grains from the mafic and felsic layers of Ablation experiments were conducted in a He atmo- banded orthogneiss have distinct morphologies and sphere to enhance sensitivity and reduce inter-element internal structures. In sample SCC1A (mafic band), most fractionation (Gunther and Heinrich, 1999). Data were grains are elongated (aspect ratios varying from 2:1 to acquired in the peak jumping mode in a series of five 4:1), ranging from 150 to 400 ␮m in length. In spite repeats of 10 s each, measuring the 202Hg, 204(Pb + Hg), of rounded terminations, the original euhedral to sub- 206Pb, 207Pb, 208Pb and 238U isotopes similarly to the hedral shape can still be recognized in many grains. procedure described in Bruguier et al. (2001). Signal was Oscillatory zoning, typical of magmatic growth, is com- acquired after a 10 s period of pre-ablation to allow for mon (Fig. 3A) although it is faint and partially obliter- crater stabilization and to remove surface contamination ated in many grains, suggesting local redistribution of as well as fall-out from previous analyses. The laser was elements during metamorphism. Dissolution and repre- fired using an energy density of 20 J cm−2 at a frequency cipitation in some grains is indicated by embayments of 3 or 4 Hz. The laser spot size was of 52 and 26 ␮min cutting the concentric zoning (Fig. 3B). Overgrowth samples SCC1A, SCC1B and SCC9, and 26 ␮m in sam- rims, where present, are usually thin (<20 ␮m), and ples SCC2, SCC5 and SCC12. Some additional analyses some grains exhibit structureless domains (Fig. 3B). All using a spot size of 15 ␮m were further made in the rims these features are interpreted as representing a mag- of zircon grains from sample SCC1A. matic zircon population affected by a metamorphic The Pb/Pb and U/Pb isotopic ratios of unknowns were event. Inherited cores were not observed in the analyzed calibrated against the G91500 zircon crystal as an exter- grains. nal ablation standard, which was measured four times In contrast with zircon grains from Sample SCC1A, each five unknowns using the bracketing technique. Data those from sample SCC1B have aspect ratio normally were reduced using a calculation spreadsheet, which between 1:1 and 2:1 and are shorter (less than 300 ␮m allows correction for instrumental mass bias and inter- long). Their main characteristic is the presence of over- element fractionation. Accurate common lead correction growths with thin oscillatory zoning, suggesting mag- in zircon is difficult to achieve, mainly because of the matic growth over preexisting crystals (Fig. 3C). Some isobaric interference of 204Hg on 204Pb. The contribu- crystals have subhedral to euhedral shapes (Fig. 3D) and tion of 204Hg on 204Pb was estimated by measuring the oscillatory zoning typical of magmatic zircons. 202Hg and assuming a 204Hg/202Hg natural isotopic com- In sample SCC2 (granitic orthogneiss) the dominant position of 0.2298. This allows to monitor the common zircon population consists of clear, subhedral to euhe- lead content of the analysed grain, but corrections often dral grains with faint oscillatory or no apparent zoning, result in spurious ages. Analyses yielding 204Pb close sometimes with inherited cores (Fig. 3E and F). to, or above the limit of detection were then rejected. The most common population of zircons in the Table 1 thus presents only analyses for which 204Pb was paragneiss sample SCC9 comprises rounded to slightly below detection limit. For instrumental mass bias, all elongated (aspect ratios up to 2.5:1) grains with clear measured standards were averaged to give a mean mass oscillatory zoning (Fig. 4A). Some grains also have bias factor and its associated error. This mass bias fac- bright, high-U, overgrowth rims (Fig. 4A), preferentially tor and associated error were then propagated with the located at the terminations of the crystals and responsi- measured analytical errors of each individual sample. ble for rounding of the original euhedral shape. A few S.P. Neves et al. / Precambrian Research 149 (2006) 197–216 203 3.2 0.4 1.2 1.4 − − − − σ 1 ± 207Pb/206Pb σ 1 ± 206Pb/238U Apparent Ages (Ma) Disc (%) σρ 1 ± 206Pb/238U σ 1 ± 207Pb/235U σ 1 ± 06 –0606 – – 0.1297 0.1268 0.000506 0.126406 6.5833 – 0.0004 – 0.1586 0.0010 6.4644 0.3681 6.5018 0.1580 0.1310 0.0087 0.2790 0.3695 0.120106 0.99 0.373006 2020 0.0007 0.17006 0.0089 0.0008 0.11806 6.8117 0.0157 0.99 0.17806 4.8532 0.98 2027 0.14706 41 0.1315 2044 0.1324 0.18506 0.1317 0.0830 0.3771 2094 0.19206 0.1315 0.2931 0.07606 42 0.1310 0.0011 0.12206 73 0.1319 0.0020 0.0070 2054 7.3206 0.10506 0.1337 0.0010 0.0046 0.96 2049 7 7.1134 0.17206 0.1257 0.0011 0.91 2063 6.7704 0.10306 0.2538 0.1317 0.0011 1657 3.5 6.4622 0.10706 0.2963 0.4037 0.1255 0.0010 6 6.4648 0.05306 0.2441 14 0.3917 0.1314 0.0009 6.8295 0.05406 33 0.1260 0.3735 0.1259 0.0014 1.3 6.4235 0.09606 23 0.0136 0.0618 0.3579 0.1259 0.0009 0.2 2111 7.1760 0.09806 0.0151 0.97 0.1082 0.3554 0.1221 0.0016 1957 6.1352 0.08006 0.0132 0.93 2186 0.1082 0.3705 0.1325 0.0011 6.7414 0.07806 0.0062 0.98 2130 0.1942 0.3707 0.1263 0.0012 6.2179 0.15806 0.0014 0.89 2046 0.2052 10 0.3952 0.1314 0.0014 5.9811 0.19306 0.0052 0.42 1972 0.1936 12 0.3545 0.1255 0.0013 62 4.5698 0.11706 0.0057 0.89 1960 0.1529 0.3721 0.1255 0.0007 2.3 70 6.7513 0.129 15.3 0.0098 0.91 2032 0.1053 0.3583 0.1313 2118 0.0011 61 6.1788 0.153 0.0116 0.91 2033 0.0872 0.3446 0.1312 2121 0.0013 30 6.7888 0.0096 0.98 2147 0.1612 0.2715 0.1251 2118 0.0019 5.7987 7 0.0083 0.90 1956 0.1137 0.3740 0.1319 2111 0.0007 25 5.7908 15 0.0051 0.94 2039 0.0749 0.3549 0.1320 0.0017 27 2124 6.3251 27 0.0041 0.84 1974 0.1460 0.3747 2147 0.0009 45 6.6435 14 0.0081 0.80 1909 0.1221 0.3352 2038 0.0017 55 6.3293 15 0.0062 0.92 1548 0.0620 0.3346 2121 0.0014 45 6.8990 3.4 0.0028 0.96 2048 0.0893 0.3495 2036 15 39 6.7767 13 6.6 0.0077 0.69 1958 0.1032 0.3674 2117 24 13 0.0049 0.92 2052 0.1266 0.3670 2041 7.7 21 19 5.4 0.0028 0.69 1863 0.1754 0.3793 2041 38 13 0.3 0.0013 0.81 1861 0.3769 1987 30 22 0.0054 0.26 1932 2132 13 15 3.9 0.0049 0.90 2017 2047 37 17 3.7 0.0088 0.71 2015 2117 23 21 3.3 0.91 2073 2036 13 17 6.5 2062 2036 22.1 6 2115 9 25 14 3.9 23 2114 18 2030 4.3 41 27 3.1 2124 10 8.5 2124 8.6 23 12 8.6 23 4.6 19 0.7 2.4 2.9 06 – 0.1302 0.0013 6.1569 0.1260 0.3429 0.0062 0.88 1901 30 2101 17 9.5 0606 – –06 – 0.132505 0.126806 –06 0.1259 0.0019 –06 0.0005 –06 6.8423 – 6.5162 0.0005 – 0.2023 0.126106 6.5767 0.2461 0.3745 0.123106 0.3728 0.1240 –06 0.1872 0.1223 0.0005 –06 0.0097 0.3788 0.1269 0.0009 –06 6.1478 0.0140 0.88 0.0008 –06 4.7008 0.99 2050 0.0005 – 5.7877 0.0107 2042 0.0812 0.1320 0.0004 – 5.5101 0.99 0.0492 0.3536 0.1322 5.4198 2071 0.0604 0.2770 0.1253 45 0.2605 0.3384 0.1319 0.0010 65 0.0044 0.1006 0.3267 0.1266 2132 0.0005 7.0809 0.0022 0.95 0.3099 0.1252 2054 0.0004 50 6.8481 0.0028 0.75 1952 0.0010 6.1540 0.0154 0.79 1576 0.0903 2042 0.0006 4.6341 25 0.0057 1.00 1879 0.1425 0.3892 0.0004 6.2522 0.98 1822 0.2326 0.3756 7 21 3.4946 3.8 1740 0.0921 0.3562 11 0.0040 0.2710 0.2549 2044 6 0.5 13 0.0077 0.80 0.0773 0.3582 2001 74 0.0134 0.98 2119 0.2025 2015 28 0.0047 1.00 2056 1991 0.0154 0.93 1964 2056 8 12 0.0044 0.99 1464 19 11 0.99 1974 4.5 36 21.3 1189 2124 7 63 6.8 2128 6 24 2033 8.5 73 15.3 2123 24 13 2051 2031 7 0.2 6 13 3.4 8 3.4 31.1 6 3.8 41.5 06 – 0.1192 0.0006 4.6583 0.2623 0.2834 0.0159 1.00 1608 79 1945 8 17.3 − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − (ppm) U (ppm) Th (ppm) Th/U 204Pb/206Pb 208Pb/206Pb 207Pb/206Pb * 999283 274 241 85 215 6837 0.31 61 0.28 110 4.87E 4.70E 0.29 59 6.63E 8776 0.5396 230 1.51E 97 205 311 105 178 281 114 0.46 0.87 103 6.18E 0.36 9.50E 5.23E 0.37 5.51E 103131 274104 118 419 271 0.43 158 4.41E 50138 0.38 4.19E 0.19 394 4.78E 188155 0.48169 3.94E 269 352 257 507 201106 80130 298258 0.57288 258 4.70E 0.31147 278 0.59 631 5.45E 3.20E 71 489 108207 323 281144 231 0.27101 0.39 118 619 7.25E 0.45 6.81E 436 0.47 3.28E 285 0.37 3.44E 75199 209 5.18E 135 95188 0.12228 472 0.48 335 3.82E 5.34E 0.33 459 351 566 6.62E 127 208 0.74 271 0.38 3.46E 0.45 4.43E 0.48 3.64E 2.59E * * * * * * * * * * * * * * * * * * * * * * * * * * * #23 #24 #30 #5 #8 #9 #15#16 137 477 131 0.27#25#26 4.37E 236#27 277#28 61#29 587 654#31 136#32 330#33 408#34 240 76 0.56#35 61 0.62#36 3.89E #37 2.95E 717 0.56#38 249 6.14E #39 122#40 225 189#41 184 30#42 340 0.31#43 540#44 3.51E 473 0.12 101 9.82E 142 269 0.30 0.26 5.13E 0.57 3.19E 3.73E #6 89 259 70 0.27 6.55E #7 #3 #4 #10#11 194#12 216#13 87#14 287 723 672 281#17 475 795#18 472#19 60 0.66#20 639 135 0.70#21 3.00E #22 2.67E 152 0.21 0.80 525 6.57E 2.16E 754 247 258 0.47 3.91E 0.34 4.36E #1 156 580 110 0.19 3.66E #2 Sample Pb SCC1A Table 1 LA-ICP-MS U–Th–Pb results for zircons from rocks of the Borborema Province (Brazil) 204 S.P. Neves et al. / Precambrian Research 149 (2006) 197–216 1.0 0.3 3.4 2.4 1.8 1.7 0.9 1.0 1.1 0.1 − − − − − − − − − − σ 1 ± 207Pb/206Pb σ 1 ± 206Pb/238U Apparent Ages (Ma) Disc (%) σρ 1 ± 206Pb/238U σ 1 ± 207Pb/235U σ 1 ± 06 0.1560505 0.07605 0.1317 0.08705 0.09205 0.07105 0.1318 0.0017 0.104 0.1319 6.7659 0.104 0.131306 0.1257 0.002906 0.1210 0.1259 0.0019 – 7.1683 0.3727 0.1263 0.0029 – 6.9519 0.0020 7.0291 0.3275 0.0026 5.9734 0.0046 0.2354 0.3944 0.0020 5.8183 0.69 0.1217 0.2867 0.382306 6.2292 2042 0.1217 0.1163 0.388206 0.0158 0.1714 0.3447 –06 0.0117 0.88 0.1175 0.0013 0.3352 –06 0.0133 0.91 2143 0.0019 0.3577 –06 22 5.8986 0.0040 0.84 2087 – 5.7713 0.0070 0.60 2114 2120 – 0.0038 0.3450 0.71 1909 0.1216 73 0.1889 0.56 0.3515 1864 0.1204 55 0.3439 1971 0.1219 2122 61 23 0.1204 0.0005 2123 19 0.0202 0.1213 0.0007 2116 34 5.6962 0.0099 3.7 0.98 0.0009 2038 18 5.6963 39 0.88 1942 0.0007 2041 5.7435 25 1906 0.0993 0.0007 2047 5.7924 39 0.1392 0.3397 5.9861 28 1.7 0.0860 0.3430 96 37 0.1 0.1409 0.3417 47 27 0.0058 6.3 0.2552 0.3489 1981 0.0081 8.7 0.98 0.3579 1981 0.0044 3.7 0.97 1885 0.0083 0.85 1901 19 0.0151 0.97 1895 28 0.99 1929 28 2.0 1972 39 3.8 06 1980 21 1963 39 – 1984 71 1963 1976 7 11 14 4.8 0.1219 10 3.1 11 4.5 1.7 0.0005 0.2 6.0312 0.0604 0.3618 0.0033 0.90 1990 15 1985 8 05 – 0.0658 0.0013 0.9231 0.0268 0.1018 0.0021 0.7206 625 –06 12 – 800 0.1265 0.1375 42 0.0008 5.7264 21.9 0.0006 7.6026 0.2653 0.3283 0.0691 0.4009 0.0151 0.99 0.0032 1830 0.89 2173 73 2050 15 2196 11 10.7 7 1.0 0606 0.136 0.137 0.1339 0.1318 0.0008 0.0015 7.1834 6.428906 0.093105 0.0827 0.3892 – 0.3539 –0605 0.0045 – 0.0020 0.90 – 0.45 2119 0.1200 1953 0.1298 0.1200 0.0010 21 0.1209 0.0005 10 5.837506 2149 7.156606 0.0012 2121 –06 0.1012 0.0016 6.0305 –06 0.3326 0.3527 5.8620 10 –06 0.3997 20 –06 0.1294 0.0053 –06 1.4 0.3088 0.3645 0.1213 0.0185 –06 7.9 0.87 0.3517 0.1215 –06 1.00 1948 0.1319 0.0069 –06 2168 0.1190 0.0008 0.0179 – 0.89 0.1214 0.0007 –06 0.97 2003 6.1294 25 0.1228 0.0009 1943 5.8041 85 0.1217 0.0004 –06 1957 6.7873 0.1257 0.1233 0.000706 2096 5.0373 33 0.0725 0.3664 0.1236 0.0017 –06 5.9431 85 0.1094 0.3466 0.1233 0.0008 –05 1956 6.2670 0.0602 0.3733 15 0.0007 –06 1969 5.9290 0.0072 0.1193 0.3070 0.1220 0.0009 – 7 6.2643 0.0038 0.95 0.0937 0.3551 0.0014 0.5 –06 6.3046 0.0055 0.88 2012 0.1596 0.3702 0.1228 18 06 6.2831 0.0035 0.91 1918 0.0721 0.3533 0.1222 24 0.0008 – 0.0068 0.95 2045 0.0935 0.3686 0.1232 – 6.0819 0.0022 0.96 1726 0.1439 0.3700 0.1233 0.0008 1.3 34 0.0092 0.40 1959 0.3696 0.1223 0.0011 18 6.0807 0.0036 0.97 2030 0.1097 1976 0.0012 26 6.0280 0.0048 0.85 1951 0.3614 0.1236 1978 0.0014 17 6.1414 0.0073 0.88 2023 0.0679 0.1282 2123 0.0003 32 6.1371 0.86 2029 0.1212 0.3592 1941 10 6.0817 11 0.0061 2027 0.3689 0.3577 1977 0.0007 44 10 0.94 0.0988 0.3615 1997 0.0007 17 6.0503 12 0.0035 1989 0.1179 0.3611 1981 23 6.7044 3.0 0.0065 0.87 0.3606 2004 6 34 10 3.7 0.0205 0.90 1978 0.2258 2009 24 11.1 0.0036 0.94 1971 0.0816 0.3551 2005 29 12 0.9 0.0069 0.63 1989 0.3792 11 0.99 1987 1986 17 12 1.6 0.0131 1985 31 21 0.0041 0.99 1997 96 0.88 1959 1989 17 11 2073 2003 33 2004 11 1990 62 16 19 18 1.0 2008 20 0.9 2074 0.7 5 0.8 10 0.3 10 2.5 0.1 − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − ) (ppm) U (ppm) Th (ppm) Th/U 204Pb/206Pb 208Pb/206Pb 207Pb/206Pb * 73 169 77 0.46 8.04E 8079 23161 148 225 177 0.64 122 6.20E 60 0.543736 7.05E 0.34 1.04E 10666 10935 24.3828 27.3136 192 0.2336 95 0.2537 5.14E 81 29.91 100 5.37E 51 19.36 98 0.16 16.59 99 17.8459 3.05E 0.2028 141 0.20 15.85 5.92E 0.1849 43.57 8.61E 14 193 5.44E 0.16 25.5941 0.44 83 5.46E 144 6.15E 0.18 39.3632 38 118 4.31E 21.82 0.20 17.45 4.51E 0.26 92 5.61 0.12 21.83 9.70E 5.48E 0.15 0.19 21.63 1.32E 4.91E 0.23 8.13E 230193 548211111 267 468 625282 306 0.49 114 190 2.87E 119 97 725 0.24123 0.30 2.67E 258 330 2.06E 0.32 368 4.29E 0.36 90 83145 1.98E 115 0.27154 0.23143 425 4.95E 112 346 4.39E 463 117 424 117 325 135 0.27 225 0.34 3.34E 86 0.29 5.55E 0.53 3.15E 4.13E 0.26 6.10E 130 373 79.56 0.21 1.77E Continued * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * #49 #20 #1 #1 #46 #50 #51#52 114#53 201 313 573#2 #3 62 178 0.20 0.31 3.97E 2.93E #9 #10 #11 #12 #5#7 55 563 376#2 0.67 1.02E #7 #9 #10 #11 54#13 35 175 89 47.22 0.27 40.13 4.25E 0.45 5.28E #6 #12 #14 #47#48 145 370 162 0.44 3.58E #4 52#8 136 73 0.53 1.19E #3#4#5 82 107#6 #8 227 363 48.23 30.69 0.21 0.08 2.55E 2.12E #15 #16 #17 #18 #19 #21 59 162 24.23 0.15 3.47E #45 SCC1B SCC2 Sample Pb Table 1 ( S.P. Neves et al. / Precambrian Research 149 (2006) 197–216 205 1.9 2.1 0.1 1.3 − − − − σ 1 ± 207Pb/206Pb σ 1 ± 206Pb/238U Apparent Ages (Ma) Disc (%) σρ 1 ± 206Pb/238U σ 1 ± 207Pb/235U σ 1 ± 05 – 0.1246 0.0015 5.517605 0.1346 0.208 0.3245 0.006505 0.0646 0.83 0.08905 1812 0.0001 0.265 1.1037 0.0658 32 2023 0.0340 0.0669 0.1238 0.0003 1.1328 0.0004 21 0.0038 1.2097 1.00 0.0484 10.4 0.1249 753 0.0333 0.1311 0.0053 22 0.99 0.0035 759 763 0.98 794 30 5 20 799 1.3 835 11 12 5.0 4.9 0505 –06 –05 –05 –05 –05 0.1300 –05 0.1295 –05 0.1291 –05 0.1219 0.0010 – 0.1299 0.0005 –05 6.5989 0.1235 0.000705 6.6790 0.1004 0.0004 –05 6.2820 0.1624 0.1299 0.0005 –05 4.3412 0.3127 0.3680 0.1294 0.0014 –05 6.5389 0.3132 0.3741 0.1304 0.0008 –05 5.3041 0.2316 0.3529 0.0004 –05 2.5316 0.0081 0.1601 0.2583 0.1196 0.0011 – 6.8323 0.0173 0.90 0.2700 0.3651 0.1278 0.0006 – 6.3456 0.017205 0.99 2020 0.1016 0.3116 0.1300 7.0925 0.013605 0.98 2048 0.3240 0.1829 0.0762 0.0012 0.0088 0.13605 0.98 1949 0.1257 0.3814 0.1305 0.0003 4.3837 0.0155 0.096 0.99 1481 0.3184 0.3557 0.1297 0.0005 38 6.4429 0.0072 0.21906 0.98 2006 0.3945 0.1243 0.0024 81 6.6770 0.017905 0.98 1748 0.2096 2099 0.0010 0.0828 81 1.1706 0.0065 0.14205 0.99 1083 0.3484 0.2658 2091 0.0006 0.0789 69 6.9160 0.0174 0.23906 0.92 2083 0.3456 0.3657 2086 0.0004 0.1191 42 6.7763 0.198 0.98 1962 0.2002 0.3725 1984 76 0.0014 5.5019 14 0.0124 0.11705 2144 0.1202 0.1114 2097 0.0798 39 0.0011 2.1517 0.0196 0.98 0.2768 0.3843 2007 6 0.0786 83 0.0002 10 3.7 1.8376 0.0188 0.11005 0.99 1519 0.1117 0.3790 1631 0.1322 31 5.9187 0.007705 0.92 2009 0.3209 2097 6 2.0 0.0465 0.1234 80 0.0012 6.6 0.0058 0.26105 0.98 2041 2090 7 0.0329 0.1885 0.0011 20 25.4 1.5553 0.0148 0.09805 0.81 2103 0.2116 0.1688 0.1273 63 681 0.0018 15 1.9876 0.0065 0.22505 0.96 2096 4.3 0.3603 92 0.0002 12.9 5.9414 0.20305 0.99 2072 1950 6 0.0026 0.0482 0.0678 88 33.6 15 6.2161 0.11205 1794 2068 0.0024 0.65 0.0737 0.1414 0.0719 0.0009 45 0.12905 2098 8 0.0117 0.80 0.7 1113 0.2243 0.1835 0.0677 27 6.1 6.7126 0.16006 0.91 1006 0.2047 0.3259 0.1086 69 0.0006 1101 18 0.20305 2105 0.0038 1984 0.3653 0.0643 31 0.0007 1.0954 0.08705 2094 4 0.0063 0.86 0.2754 0.1202 0.0010 22.1 14 1.3831 0.12305 2020 6 0.0115 0.92 0.3826 0.0803 0.0016 13 853 1.1012 0.20105 61 0.0105 0.93 2.8 1086 0.0308 0.0647 1264 0.0010 55 13 1.7673 0.145 0.94 2.7 1818 0.0179 0.1171 0.1183 1171 0.0004 38.2 1.0284 0.342 9 0.0154 2007 0.0319 0.1394 0.0718 1943 0.0006 0.4 5.7776 21 6 0.98 0.0339 0.1180 0.0677 0.0020 34 2.1497 32 0.0032 1.0 2088 0.0266 0.1181 0.0710 0.0003 56 1191 11.2 1.0637 27 0.0011 0.96 0.2325 0.1159 0.1220 1161 0.0005 49 11.9 5.0870 0.0032 0.63 0.0673 0.3487 2128 4 0.0005 714 14.1 1.1083 0.0015 0.93 0.0546 0.1943 2006 0.0010 72 842 1.3235 0.0024 0.65 0.1057 0.1193 31 0.0010 719 1.3802 28 0.0131 0.80 0.0480 0.3118 2060 719 2.5433 24 18 28.4 0.0059 0.93 0.0516 0.1120 707 6.5 0.0048 0.97 1928 0.0252 0.1418 3 6 14.5 18 863 0.0064 0.79 1144 0.0257 0.1411 13 0.0048 0.99 0.1512 8 984 727 14 859 0.0054 0.99 1750 62 1776 0.0016 0.98 32 684 17 752 0.0009 0.62 1959 855 28 21 0.62 1203 17.3 31 851 29 908 27 14.5 28 763 1931 16.3 33 30 6 59.5 16 980 9 6.0 860 5 1.6 67 4.9 5 956 1986 14 4.8 9.4 17 30.2 29 14 0.6 11.1 54.3 0506 –05 –04 – – 0.1283 0.1267 0.1219 0.0615 0.0006 0.0006 5.8296 0.0015 5.9225 0.0009 4.9253 0.2949 0.8451 0.1740 0.3295 0.2436 0.3389 0.0713 0.2930 0.0156 0.0996 0.0099 0.94 0.0132 0.99 1836 0.0046 0.91 1881 0.94 1657 75 612 48 2075 65 2053 27 1984 658 8 8 22 11.5 8.4 16.5 30 7.1 − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − ) (ppm) U (ppm) Th (ppm) Th/U 204Pb/206Pb 208Pb/206Pb 207Pb/206Pb * 4442 12433 115 84 7866 91 0.6870 0.68 173 1.14E 58 1.48E 186 9963 0.63 2.38E 14652 0.5736 183 1.93E 0.78 149 125 1.30E 102 127 0.68 86 1.45E 0.85 1.48E 0.85 2.31E Continued * * * * * * * * #15 46 136 84 0.62 2.26E #4 74#9 556#11 29 365 18 229 0.66 115 1.04E 72 87 0.31 1.74E 0.75 3.09E #16 59 231 98 0.42 1.59E #5 83#10 566 56#12 162 20 139 0.29 149 8.74E 60 2 0.44 1.47E 0.01 3.40E #1 45 226 75 0.33 2.21E #6 #7#8 120#9 #10 69#11 62 341#12 55#13 291#14 383 33 205 295 326#17 1.12 156 103#18 125 8.01E 1.01 62#19 1.32E #20 0.76 64 28#21 0.39 1.51E 163#22 1.40E 0.62 67 348 118 2.57E #2 205#3 221 0.72 53 1.11E 62 0.59 121#6 3.09E #7 309#8 21 150 0.55 34 292 1.21E 28 110 104 92 764 0.09#13 0.73#14 78 1.57E 38 1.47E #15 298 52 27#16 22 0.74#17 16 267#18 0.39 3.12E 0.57 64 220#19 4.39E 2.21E 58 162#20 71 13 135#21 167 131 181#22 109 43 265#23 0.27 69 13#24 0.76 99 394 59 14 1.94E 0.67 136 3.00E 26 349 4.12E 0.51 65 75 67 0.32 3.52E 0.51 90 100 131 1.40E 1.17E 0.66 35 0.17 39 0.29 5.95E 5.95E 45 1.51E 0.46 0.43 4.34E 0.34 3.41E 2.61E #1 47 134 74 0.55 1.15E #2#3#4 62#5 47 3 188 171 168 31 129 0.89 1 0.76 8.33E 1.16E 0.04 2.44E SCC9 Sample Pb SCC5 Table 1 ( 206 S.P. Neves et al. / Precambrian Research 149 (2006) 197–216 2.6 6.6 0.3 0.2 0.1 6.5 3.3 − − − − − − − σ 1 ± 207Pb/206Pb σ 1 ± were included in the age calculation, * 206Pb/238U Apparent Ages (Ma) Disc (%) σρ 1 ± 206Pb/238U σ 1 ± 207Pb/235U σ 1 ± 06 – 0.1237 0.0006 5.7574 0.0909 0.3376 0.0051 0.96 1875 24 2010 8 6.7 0404 – – 0.0609 0.0601 0.001804 0.0010 0.8968 – 0.8720 0.0314 0.0214 0.1067 0.1053 0.0607 0.0020 0.0018 0.55 0.71 0.0007 654 645 0.8585 12 0.0278 11 0.1026 637 605 0.0031 0.93 62 630 37 18 628 25 0505 – –0505 –06 0.0625 –05 0.0619 –05 –06 0.0008 –06 0.0602 0.0006 –06 0.8913 0.0604 – 0.8332 0.1190 – 0.0227 0.0603 0.0004 0.0305 0.1035 0.1225 0.0012 0.8269 0.0976 0.1216 0.0008 0.8145 0.1229 0.0006 5.3509 0.0023 0.0673 0.1252 0.0010 0.8247 0.0034 0.87 0.0272 0.0996 0.0010 5.4307 0.96 0.1082 0.0978 0.0005 635 5.3739 0.0275 0.3261 0.0011 600 5.7922 0.0081 0.0908 0.0992 6.4045 0.0026 1.00 0.0755 0.3214 13 0.0062 0.81 0.2003 0.3204 612 20 0.0031 0.94 0.0931 0.3418 601 690 0.0047 0.95 1819 0.3710 671 0.0037 0.88 610 47 0.0117 0.81 1797 16 0.0044 0.99 1792 30 26 611 0.81 1895 22 18 619 2034 1942 23 7.9 10.5 18 613 1994 56 15 1980 21 41 12 1999 2032 23 2.8 14 6.3 15 0.5 9.9 7 15 9.5 5.2 05 0.180 0.0734 0.0007 1.5632 0.0481 0.1545 0.0046 0.96 926 26 1025 19 9.6 0605 0.08806 0.23805 0.21505 0.17805 0.0703 0.20305 0.0780 0.17306 0.0787 0.13805 0.0744 0.0004 0.127 0.1387 0.0005 1.2421 0.207 0.0741 0.0004 2.0370 0.0682 0.0016 1.9194 0.0274 0.2721 0.0006 1.2313 0.0388 0.1282 0.0685 0.0006 7.5496 0.0303 0.1894 0.0005 1.4389 0.0417 0.1768 0.0020 1.2866 0.0027 0.1135 0.1201 0.0009 20.9677 0.0034 0.97 0.0325 0.3947 1.1344 0.0026 0.94 0.0258 0.1408 778 0.7087 0.0031 0.93 1118 0.1369 0.5589 0.0057 0.77 1049 0.0242 0.0029 0.96 0.1202 731 16 0.0026 0.93 2145 18 0.0184 0.93 14 849 0.98 936 0.0020 1147 827 2862 18 0.76 1166 26 731 1052 17 2211 11 13 14 76 1045 11 17.0 3318 11 2.5 874 44 10.0 7 30.5 883 17 3.0 11 15 18.8 13.7 28 5.4 17.1 05 0.119 0.0659 0.0014 1.2907 0.0294 0.1420 0.0012 0.37 856 7 804 44 0505 0.13905 0.174 0.353 0.0669 0.0780 0.0617 0.0012 0.0002 1.1766 0.0005 1.4617 0.9321 0.0228 0.0354 0.1275 0.0143 0.1359 0.1095 0.0009 0.0033 0.35 0.0014 1.00 774 0.86 821 670 5 19 8 835 1147 665 38 4 17 7.4 28.4 − − − − − − − − − − − − − − − − − − − − − − − − − − − − ) and refer to last digits. The right hand column is percentage discordance assuming recent lead losses. For each studied rock, analyses labelled (ppm) U (ppm) Th (ppm) Th/U 204Pb/206Pb 208Pb/206Pb 207Pb/206Pb σ * 34 32 42 26 60 0.806 1.44 1.42E 1.35E 59 20 0.34 1.07E 2512 24268 13320 13 27447 817 218 0.05 2.06 67 484 2.16E 307 4.15E 0.08 52 1.41 1.10E 1.77E 0.11 2.34E Continued * * * * * * * * #4 #5 #14 119 355 12 0.03 6.08E #6 #13 #2 #3 #7#8 101#9#10#11 57 137 315#12 125 117 185 441 13 360 313 18 26 0.04 28 5.88E 13 0.10 0.06 0.08 1.22E 5.25E 0.04 5.56E 4.51E #29 21 122 72 0.59 3.85E #30 91 725 171 0.24 7.39E #1 #31#32 63#33 87#34 17#35 74 301#36 36 442#37 44 128#38 214 121 160 333 44 240 70 312 0.71 112 176 0.75 110 1.17E 333 112 9.36E 0.55 0.70 74 3.21E 0.46 156 1.16E 0.36 1.56E 0.42 1.90E 0.47 3.78E 1.79E #28 22 149 42 0.28 2.39E #25#26 47#27 27 28 340 187 201 77 69 203 0.23 0.37 1.43E 1.01 2.23E 2.70E Sample Pb SCC12 whereas others were omitted. Errors are 1 Table 1 ( S.P. Neves et al. / Precambrian Research 149 (2006) 197–216 207

Fig. 3. SEM images of selected dated zircon grains in orthogneiss samples showing position of the LA-ICP-MS spot and corresponding age (erros quoted at the 1σ level). (A, B) Sample SCC1A (mafic layer of banded orthogneiss). (A) Oscillatory-zoned zircon with rim overgrowth at the right side. (B) Rounded grain with irregular zoning. (C, D) Sample SCC1B (felsic layer of banded orthogneiss). (C) Fragment of zircon grain containing large elliptical core with coarse oscillatory zoning surrounded by overgrowth rim with thin oscillatory zoning. (D). Euhedral zircon grain with thinly oscillatory-zoned overgrowth at upper and right side. (E, F) Sample SCC2 (granitic orthogneiss). (E) Fragment of large, homogeneous euhedral grain with oscillatory-zoned core. (F) Grain with broadly elliptical form that yielded the oldest age of all analyzed zircons in orthogneiss samples. elongated grains preserve subhedral shapes typical of 6. U–Pb zircon data magmatic zircon, suggesting transport over short dis- tances (Fig. 4B). Table 1 shows the results of analytical data for the Two zircon populations are observed in sample studied samples. In the following, ages of zircons are SCC12 (migmatitic paragneiss leucosome). One con- expressed in terms of either their 207Pb/206Pb ratios tains elongated (aspect ratio up to 4:1), subhedral to (grains older than 1 Ga) or their 206Pb/238U ratios (grains euhedral zircon grains with faint oscillatory zoning and with Neoproterozoic ages). Errors for single analysis and thin or absent overgrowth rims (Fig. 4C). The other con- mean ages are quoted at the 2σ level. sists of rounded (Fig. 4D) to slightly elongated grains with overgrowths that may truncate internal oscillatory 6.1. Sample SCC1 (1A and 1B) zoning. Inherited cores are present in some grains of the latter population. Analyses of zircons from sample SCC1A (mafic layer Finally, the deformed granodiorite sample SCC5 from of banded orthogneiss) fall into two age groups that the Alcantil pluton contains a homogeneous population define two Pb loss trends in the concordia diagram of small (∼100 ␮m long), subhedral to anhedral, slightly (Fig. 5a). For each population, analyses showing dis- elongated grains. cordance smaller than 5% can be pooled together to 208 S.P. Neves et al. / Precambrian Research 149 (2006) 197–216

Fig. 4. (A, B) SEM images of selected zircon grains in sample SCC9 (pelitic gneiss). (A) Rounded zircon grain with overgrowth rims at upper left and lower right sides truncating oscillatory-zoned core. (B) Elongated zircon grain with no apparent zoning. (C, D) SEM images of selected zircon grains in sample SSC12 (leucosome from migmatitic paragneiss) showing position of the LA-ICP-MS spot and corresponding age (errors quoted at the 1σ level). (C) Subhedral grain with thin overgrowth rim. (D) Rounded grain with thin overgrowth rims at the left and right sides. define 207Pb/206Pb weighted means of 2125 ± 7 and Analyses of zircons from the leucocratic band SCC1B 2044 ± 5Ma(Fig. 5b). The clear distinction of these two display a different distribution when compared with age groups strongly suggests that they correspond to two sample SCC1A. Most grains plot close to Concordia different events. The lack of inherited cores in most zir- (see Fig. 6a) at about 1.98 Ga, and, together with anal- con grains suggests that the group with the older age ysis #5 (Table 1), define a discordia line with upper represents igneous crystallization of the protolith. This and lower intercepts of 1985 ± 12 and 578 ± 37 Ma is consistent with well preserved oscillatory zoning in the (MSWD = 1.2). The upper intercept is well constrained grains where ca. 2125 Ma ages were obtained (Fig. 3A). by concordant analyses and ten highly concordant grains Truncation of oscillatory zoning, recrystallized zones or give a 207Pb/206Pb weighted mean of 1972 ± 8Ma regions with fading oscillatory zoning observed in some (Fig. 6b), in agreement with the upper intercept age. grains (Figs. 3A and B) are typical of magmatic zir- The Th/U ratio of these grains (ranging from 0.2 to 0.7; cons modified by high-grade metamorphism (e.g. Corfu Table 1) is typical of magmatic zircons (Williams and et al., 2003). The youngest age of ca. 2044 Ma is thus Claesson, 1987), which suggests that the 1972 Ma age interpreted as representing the Transamazonian meta- corresponds to crystallization of the zircons. Since these morphic event. Because there is no discernable differ- analyses were obtained from large rounded cores sur- ence in the Th/U ratios between zircons of the two age rounded by a thin oscillatory zoned rim (see Fig. 3C), it groups (Table 1), local redistribution by recrystalliza- is concluded that the age of 1972 Ma corresponds to that tion processes without new metamorphic growth is the of the source rocks that underwent anatexis to produce most likely explanation for the igneous-like high Th/U the leucocratic band. It is probably noteworthy that this (>0.1; Williams and Claesson, 1987) ratio of the zir- age is similar to the U–Pb age of 1974 Ma obtained by Sa´ con domains with ca. 2044 Ma ages. Overgrowth rims et al. (2002) from an orthogneiss some kilometers to the that clearly represent new zircon growth revealed to southeast (Fig. 2), suggesting that the orthogneiss was be too thin to be accurately dated. Analyses showing the main source component for the melt. One grain is high discordance indicate Pb losses that could be related concordant at 2096 ± 14 Ma, indicating the source also either to a young (e.g. Brasiliano) event or to recent, included a ca. 2.1 Ga old component. One euhedral zir- zero age, disturbances, or even a combination of both con grain (see Fig. 3D) yielded a 206Pb/238U apparent age (Fig. 5a). of 625 ± 24 Ma (Fig. 6a). The high Th/U ratio (0.67) of S.P. Neves et al. / Precambrian Research 149 (2006) 197–216 209

Fig. 5. (a) U–Pb concordia diagram for zircons from sample SCC1A (mafic layer of banded orthogneiss). (b) Zoom showing the two Fig. 6. (a) Concordia diagram showing discordia line for zircons from weighted mean ages of Paeloproterozoic zircons. sample SCC1B (felsic layer of banded orthogneiss). (b) Zoom showing the 206Pb/207Pb weighted mean age of concordant Paleoproterozoic this grain (Table 1), its euhedral shape and the magmatic zircons. oscillatory zoning of overgrowths (Fig. 3D) are inter- preted as indicating growth from a magma. Therefore, corresponding to crystallization of the granitic pro- this age most likely corresponds to the crystallization of tolith. Three other grains yielded older ages indicating the leucocratic band, implying that the mesoscopic struc- inherited source components of 2196 ± 14 (Fig. 3F), ture of the banded orthogneiss is a late Neoproterozoic 2123 ± 24 and 2074 ± 20 Ma. The two latter roughly feature, resulting from intrusion of syntectonic granitic correspond to the two mean ages obtained in sample melts in a preexisting protolith. SCC1A. These results are interpreted as indicating that the granitic orthogneiss is a late-Transamazonian 6.2. Sample SCC2 intrusion containing a small proportion of inherited zircon grains. Sixteen near concordant analyses of zircon grains from the orthogneiss sample SCC2 yielded a well- 6.3. Sample SCC9 constrained 207Pb/206Pb weighted mean age of 1991 ± 5Ma(Fig. 7). Some of these grains still preserve U–Pb data for detrital zircons from paragneiss sam- euhedral shapes (Fig. 3E), which together with high ple SCC9 exhibit ages ranging from more than 3320 to Th/U ratios (see Table 1) indicates crystallization from ca. 665 Ma (Table 1). Data is reported in the concor- a magma. The 1991 ± 5 Ma age is thus interpreted as dia diagram (Fig. 8a) and in a cumulative probability 210 S.P. Neves et al. / Precambrian Research 149 (2006) 197–216

Fig. 7. U–Pb concordia diagram for zircons from sample SCC2 (granitic orthogneiss). plot (Fig. 8b). Most analysis fall on or near the con- cordia curve and those with less than 5% discordance show age peaks at ca. 2220, 2060–1940, 1200–1150, 860–760 and 665 ± 34 Ma. Several discordant grains have ages between 1100 and 900 Ma and a small peak is observed around 1690 Ma. Grains from all age groups have high Th/U ratios. Together with the oscillatory zon- ing observed in most grains, this indicates provenance of grains from igneous protoliths (Williams and Claesson, 1987), which constrain the deposition of the supracrustal sequence to be younger than the youngest grain (ca. 665 Ma) in the zircon population.

Fig. 8. (a) U–Pb concordia diagram for zircons from sample SCC9 6.4. Sample SCC12 (pelitic gneiss). Inset: zoom at the Neoproterzoic showing the U–Pb age of the youngest grain in the zircon population. Green, concor- On a concordia plot (Fig. 9A), analyses of zircons dant grains; red, discordant grains. (b) Histogram plot for 206Pb/207Pb from the leucosome of a paragneiss, except for one (#7; ages of the analyzed zircons. Green, concordant grains; red, discor- Table1) define a discordia line (MSWD = 1.1) with upper dant grains. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of the article.) and lower intercepts at 2041 ± 15 and 626 ± 15 Ma, respectively. Paleoproterozoic ages were obtained from rounded zircons grains (Fig. 4D) that have low Th/U to 2.06) suggest that the laser beam struck a Th-rich ratios (0.04–0.1; Table 5), typical of metamorphic zir- inclusion, whereas the euhedral shape (Fig. 4C) and low cons. These grains are interpreted as inherited from Th/U ratio of other grains is typical of zircons grown a protolith metamorphosed at ca. 2040 Ma. This is in under high grade conditions. The most precise lower ± agreement with analysis #12 (Table 1), which is concor- intercept age of 626 15 Ma is therefore interpreted as dant at 2032 ± 30 Ma and reinforces the interpretation of dating crystallization of the leucosome, and is thus taken the data for sample SCC1A that the peak of Transamazo- as our best estimate for the high-grade metamorphism of nian metamorphism occurred around this time. Zircons the supracrustal sequence during the Brasiliano orogeny. with Neoproterozoic ages plot near the concordia and have a 206Pb/238U weighted mean age of 632 ± 17 Ma 6.5. Sample SCC5 (Fig. 9b) overlapping the lower intercept of the discordia line. These grains yield both high and low Th/U ratios Analyses of zircon from the Alcantil pluton (SCC5; (Table 1) typical of magmatic and metamorphic zircons, Table 1) define a discordia line (Fig. 10a) with upper respectively. The high Th/U ratios of some grains (up and lower intercepts of 2103 ± 11 and 619 ± 36 Ma, S.P. Neves et al. / Precambrian Research 149 (2006) 197–216 211

Fig. 9. (a) Concordia diagram showing discordia line for zircons from sample SCC12 (leucosome of migmatitic paragneiss). (b) Zoom show- Fig. 10. (a) Concordia diagram showing discordia line for zircons from 206 207 ing the 206Pb/238U weighted mean age of concordant Neoproterozoic sample SCC5 (Alcantil pluton). (b) Zoom showing the Pb/ Pb zircons. weighted mean age of concordant Paleoproterozoic zircons. con. In this hypothesis, the zircon population would con- respectively. The lower intercept is constrained by anal- sist almost entirely of xenocrystic grains inherited from a ysis #4 (Table 1), which yielded a 206Pb/238U age of homogeneous Paleoproterozoic source. Because this is a 612 ± 54 Ma and a low Th/U ratio of 0.04, typical of rather unusual situation for granitic magmas, the second growth in the solid state. This indicates that the gran- possibility, that emplacement took place at 2097 ± 5Ma odiorite was metamorphosed at 619 ± 36 Ma, the more during the Transamazonian orogeny, is considered more precise lower intercept of the discordia line. Most grains likely. The emplacement age of ca. 2100 Ma is younger have older, mainly Paleoproterozoic ages, and a batch of but comparable to that of the older age found in the eight concordant analyses yields a 207Pb/206Pb weighted orthogneiss sample SCC1A (ca. 2125 Ma), suggesting mean age of 2097 ± 5Ma(Fig. 10b). One grain (#17; that the Alcantil pluton could represent less strained por- Table 1) has a low discordance degree, but yields a sig- tions of basement orthogneisses in the region. nificantly younger age (2068 ± 8 Ma) suggesting it has undergone disturbances, possibly during the ca. 2044 Ma 7. Discussion Transamazonian event. The above results could be interpreted in two ways. 7.1. Tectonothermal evolution of the study area First, that intrusion occurred during the Brasiliano orogeny and that temperature remained high enough This work clearly reveals that two main tectonother- after emplacement to allow growth of metamorphic zir- mal events affected the study area, one in the Pale- 212 S.P. Neves et al. / Precambrian Research 149 (2006) 197–216 oproterozoic (Transamazonian orogeny) and the other intriguing, as rocks with these ages have not yet been at the end of the Neoproterozoic (Brasiliano orogeny). identified anywhere in the Borborema Province. It is The age pattern of sample SCC1A (mafic layer of tentatively attributed to late Mesoproterozoic extension banded orthogneiss) allows placing tight constraints on and intraplate magmatism preceding the more exten- the events associated with the Transamazonian orogeny. sive Cariris Velhos rifting event. Felsic volcanic rocks The lack of inherited cores, as revealed by SEM and granites related to the Cariris Velhos event (now images, suggests that the age cluster of 2125 ± 7Ma metavolcanics and orthogneisses) in the Alto Pajeu´ belt corresponds to the crystallization age of the banded constitute the most likely source for zircons with ca. orthogneiss protolith. Six whole-rock samples of banded 950–1050 Ma ages. A source for the abundant zircon orthogneiss display geochemical characteristics simi- grains with mid-Neoproterozoic ages might be related lar to calc-alkaline magmas, suggesting generation in to magmatic episodes preceding and coeval with basin a setting (Sa´ et al., 2002). Considering formation. this, the age reported here could correspond to juve- The Neoproterozoic age of one magmatic zircon in nile crustal accretion. The younger age (2044 ± 5 Ma) the felsic layer of banded orthogneiss (625 ± 24 Ma), found in sample SCC1A is associated with metamor- the maximum deposition age of the Surubim sequence phic features observed in the analyzed zircon grains (665 Ma), the crystallization age of the leucosome from a and is interpreted as dating the peak of Transamazo- migmatitic paragneiss (626 ± 15 Ma), and the metamor- nian metamorphism, possibly marking a major colli- phic age of the Alcantil pluton (619 ± 36 Ma) show that sional event. This is corroborated by the occurrence high-temperature metamorphism was coeval with forma- of metamorphic zircons with this age in the paragneiss tion of a flat-lying foliation in basement and supracrustal leucosome sample SCC12. The age of 1992 ± 7Maof rocks. This metamorphism is clearly separated from sample SCC2 (granitic orthogneiss), and the mean age transcurrent shear zone development because the oldest of 1972 ± 8 Ma for xenocrystic zircons from sample plutons deformed in the magmatic stage by strike-slip SCC1B (felsic layer of banded orthogneiss) are inter- shearing are younger than 592 Ma (Guimaraes˜ and Da preted as reflecting a stage of late to post-orogenic Silva Filho, 1998; Neves et al., 2004). Although the magmatism. importance of the Transamazonian event in the study The age pattern of the paragneiss sample SCC9 area is obvious, fieldwork (Neves et al., 2000, 2005) and reveals provenance of its protolith mainly from Paleo- the geochronological results from this study indicate that proterozoic and mid-Neoproterozoic sources, and con- the dominant mesoscopic ductile fabric in Paleoprotero- strains the deposition of the supracrustal sequence to zoic orthogneisses was produced during the Brasiliano be younger than 665 Ma (Fig. 8a and b). The Paleo- orogeny. proterozoic ages correspond closely to the Transama- zonian event and may represent derivation of detrital 7.2. Regional correlations grains from nearby orthogneisses, although more dis- tal sources cannot be excluded. Proximal sources with 7.2.1. Basement gneisses Archean ages that could provide the oldest analyzed The two age groups in sample SCC1A are similar zircon grain (>3320 Ma) have not yet been directly to those found in samples from the eastern portion of dated in the central domain, but their existence is the Sao˜ Francisco craton, where recent SHRIMP U–Pb suggested by Sm–Nd model ages of Paleoproterozoic data indicate magmatic crystallization at 2.2–2.1 Ga and orthogneisses (Van Schmus et al., 1995; Brito Neves high-grade metamorphism at 2.08–2.05 Ga (Silva et al., et al., 2001b). However, even the oldest Sm–Nd ages 2002). In the Borborema Province, most zircon grains are generally younger than 3300 Ma, which favors a that yielded Paleoproterozoic U–Pb ages were analyzed more distal source. This source may be located either by conventional methods (see Brito Neves et al., 2000, within an Archean nucleus identified in the northeast- and Neves, 2003, for a review of available data). The ernmost part of the Borborema Province (Dantas et spread of ages, mainly from 2.25 to 2.0 Ga, may in part al., 1998, 2004), ∼250 km to the north of the study reflect mixed ages resulting from a combination of inher- area, or within the Sao˜ Francisco craton. Grains with ited zircon cores, primary igneous zircon crystalliza- late Paleoproterozoic ages of ca. 1690 Ma may have tion, and metamorphic recrystallization. Nevertheless, their source in augen gneisses/meta-anorthositic com- the existing data point out to an important period of crust plexes (Accioly et al., 2000), which occur to the east generation at 2.2–2.1 Ga, followed by deformation and of the study area (Fig. 2A). The abundance of zir- metamorphism, and then by intrusion of late- to post- con grains with ages in the interval 1200–1150 Ma is tectonic plutons. S.P. Neves et al. / Precambrian Research 149 (2006) 197–216 213

7.2.2. Supracrustal sequences Alto Pajeu´ belt are typical of intraplate magmas, not of The maximum deposition age of the Surubim com- -related ones (Bittar and Campos Neto, 2000; plex is similar to that of the Cachoeirinha Group in the Bittar et al., 2001; Neves, 2003; Guimaraes˜ and Brito Cachoeirinha belt (Kozuch, 2003; Medeiros, 2004), and Neves, 2004). These observations seriously cast in doubt its zircon age pattern is remarkably similar to that found the existence of the Cariris Velhos event as an important (Van Schmus et al., 2003) in the Serido´ belt (Fig. 1B). orogeny. Several observations also suggest that the Surubim com- The Neoproterozoic age of deposition of supracrustal plex and the Sertaniaˆ complex in the Alto Moxoto´ belt are sequences and a common flat-lying foliation in basement correlated. Both complexes consist of the same rock type gneiss and metasedimentary belts is observed throughout association, have similar metamorphic grade (although the Borborema Province (Caby and Arthaud, 1986; Caby migmatization is more frequent in the Sertaniaˆ complex), et al., 1995; Neves et al., 2000, 2005). It is no longer and display comparable carbon isotope signature in mar- possible to claim that the Brasiliano orogeny was only bles (Santos et al., 2002). Although eight zircon grains responsible for granite intrusion and strike-slip shearing, from two samples of the Sertaniaˆ complex had yielded as still advocated in several recent studies (Jardim de Sa´ U–Pb SHRIMP ages around 2.0 Ga and interpreted as et al., 1995; Sa´ et al., 2002; Araujo´ et al., 2003; Santos et indicating Paleoproterozoic sedimentation (Santos et al., al., 2004b). The present architecture of the Borborema 2004a), this only represents the maximum age of depo- Province is a product of the Brasiliano orogeny, although sition. it is clear the importance of the Transamazonian orogeny The probable connection between supracrustal suc- as a crust-forming event. cessions in the East Pernambuco, Alto Moxoto,´ Cachoeirinha and Serido´ belts are consistent with depo- 7.3. Implications for western Gondwana sition in a regionally extensive basin formed dur- ing broad-scale lithospheric extension. The small time The results of this study and the recent synthesis span between deposition and deformation can explain by Ferre´ et al. (2002) and Toteu et al. (2004) on the the overall high-temperature metamorphism, as high geodynamic evolution of Nigeria and Cameroon, respec- thermal gradients resulting from crustal thinning can tively, strengthen the earlier suggestion (Neves, 2003; be maintained in the subsequent contractional phase Neves et al., 2004) that these belts shared a common (Thompson, 1989; De Yoreo et al., 1991; Thompson et evolution throughout most of the Proterozoic. Common al., 2001). features include (1) extensive (ca. 2.1 Ga) Paleoprotero- zoic crust, (2) dominance of metasedimentary sequences 7.2.3. Tectonothermal events with Neoproterozoic deposition ages, (3) ubiquitous Evidence for a metamorphic event in the early Neo- presence of flat-lying fabrics of late Neoproterozoic proterozoic was not found in this study and in all studies age (∼640–600 Ma), and (4) dominance of transcur- conducted so far in the central domain (Van Schmus rent/transpressional deformation after 600 Ma. The lack et al., 1995; Leite et al., 2000b; Brito Neves et al., of evidence for closure of large oceanic domains in 2001a,b; Kozuch, 2003; Medeiros, 2004). Contractional all these regions does not support the interpretation of deformation of this age during the proposed Cariris the Borborema Province as a series of amalgamated Velhos orogeny (Brito Neves et al., 1995) has been terranes (e.g. Santos and Medeiros, 1999; Santos et based on the interpretation that the early Neoprotero- al., 2004a,b). Destabilization of a preexisting conti- zoic metaigneous and metasedimentary succession of nent formed at the end of the Transamazonian/Eburnean the Alto Pajeu´ belt represents a subduction arc assem- orogeny (the supercontinent of Rogers, 1996) blage intruded by syncollisional granites (Santos and provides the simplest explanation to the above find- Medeiros, 1999; Kozuch, 2003). However, the same ings. Several attempts to fragment this supercontinent top-to-the-WNW/NW tectonic transport is found in the are recorded by late Paleoproterozoic to Neoprotero- supracrustal succession and augen gneisses of the Alto zoic intraplate extensional and magmatic events repre- Pajeu´ belt (Medeiros, 2004), and in the Surubim com- sented by failed and A-type granites and related plex (Neves et al., 2005; this study), the Sertaniaˆ com- rocks. A final period of plate-wide extension occurred plex (Santos et al., 2004a), and the Cachoeirinha Group in the mid/late Neoproterozoic. This was immediately (Medeiros, 2004). Identical kinematics in these four followed by convergence and contractional deformation belts strongly indicates deformation during the Brasil- marking the beginning of the Brasiliano/Pan-African iano orogeny. Furthermore, the geochemical character- orogeny, which essentially occurred in an intracontinen- istics of the metavolcanic and metaplutonic rocks of the tal setting. 214 S.P. Neves et al. / Precambrian Research 149 (2006) 197–216

7.4. Summary and conclusions Bittar, S.M.B., Guimaraes,˜ I.P., Campos Neto, M.C., Kozuch, M., Lima, E.S., Accioly, A.C.A., 2001. Geoqu´ımica preliminar de The main conclusions of this study concerning the metabasitos do complexo Riacho Gravata,´ dom´ınio tectonicoˆ Rio Pajeu,´ PE-Brasil. Estudos Geol. 11, 53–66. Precambrian tectonic and geochronological evolution of Brito Neves, B.B., Van Schmus, W.R., Santos, E.J., Campos Neto, the study area in the East Pernambuco belt can be sum- M.C., Kozuch, M., 1995. O evento Cariris Velhosna Prov´ıncia Bor- marized as follows: (1) 2.15–2.10 Ga: generation of juve- borema: integrac¸ao˜ de dados, implicac¸oes˜ e perspectivas. Revista nile crust, (2) 2.05–2.03 Ga: peak Transamazonian meta- Brasileira de Geocienciasˆ 25, 279–296. morphism, (3) 1.99–1.97 Ga: intrusion of late orogenic Brito Neves, B.B., Santos, E.J., Van Schmuss, W.R., 2000. Tectonic history of the Borborema province. In: Cordani, U.G., Milani, E.J., magmas, (4) after 665 Ma: deposition of supracrustal Thomaz Filho, A., Campos, D.A. (Eds.), Tectonic Evolution of sequences and (5) 630–610 Ma: development of flat- South America. Proceedings of the 31st International Geological lying fabrics and Brasiliano high-grade metamorphism. Congress. Rio de Janeiro, pp. 151–182. Available data from the literature, in addition, support the Brito Neves, B.B., Campos Neto, M.C., Van Schmus, W.R., San- intrusion of anorogenic plutons at 1.7–1.5 Ga (Accioly tos, E.J., 2001a. O “Sistema” Pajeu-Paraibaeo“Macic¸o” Sao˜ Jose´ do Campestre no leste da Borborema. Revista Brasileira de et al., 2000; Sa´ et al., 2002), and the development of Geocienciasˆ 31, 173–184. transcurrent shear zones and abundant magmatism at Brito Neves, B.B., Campos Neto, M.C., Van Schmus, W.R., Fer- 590–580 Ma (Neves et al., 2000, 2004). Most of these nandes, T.M.G., Souza, S.L., 2001b. O terreno Alto Moxotono´ features are found in other sectors of the Borborema leste da Para´ıba (Macic¸o Caldas Brandao).˜ Revista Brasileira de Province (Neves, 2003) and in the Nigeria and Cameroon Geocienciasˆ 31, 185–194. Bruguier, O., Telouk, P., Cocherie, A., Fouillac, A.M., Albarede, F., provinces (Ferre´ et al., 2002; Toteu et al., 2004; Njiosseu 2001. Evaluation of Pb–Pb and U–Pb laser ablation ICP-MS zircon et al., 2005), suggesting a shared evolution during most dating using matrix-matched calibration samples with a frequency of the Proterorozoic. quadrupled (266 nm) Nd-YAG laser. Geostandards Newslett. 25, 361–373. Caby, R., Arthaud, M.H., 1986. Major Precambrian nappes of the Acknowledgments Brazilian belt, Ceara,´ northeast Brazil. Geology 14, 871–874. Caby, R., Sial, A.N., 1997. Kyanite–garnet–staurolite thermal aure- LA-ICP-MS analyses were conducted as part of post- oles around some Neoproterozoic epidote-bearing granitoids, NE Brazil. In: Proceedings of the II International Symposium on Gran- doctoral studies by SPN financed by the Brazilian agency ites and Associated Mineralizations, Salvador, p. 183 (abstracts). Conselho Nacional de Desenvolvimento Cient´ıfico e Tec- Caby, R., Sial, A.N., Arthaud, M.H., Vauchez, A., 1991. Crustal evolu- nol´ogico (CNPq). Samples were collected during field- tion and the Brasiliano orogeny in Northeast Brazil. In: Dallmeyer, work funded by the Funda¸c˜ao de AmparoaCiˆ ` encia R.D., Lecorch´ e,´ J.P.(Eds.), The West African Orogens and Circum- e Tecnologia do Estado de Pernambuco (FACEPE). Atlantic Correlatives. Springer, Berlin, pp. 373–397. Caby, R., Arthaud, M.H., Archanjo, C.J., 1995. Lithostratigraphy and The comments from two anonymous reviewers helped petrostructural characterization of supracrustal units in the Brasil- improving the manuscript. iano Belt of Northeast Brazil: geodynamic implications. J. S. Am. Earth Sci. 8, 235–246. 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