Journal of South American Earth Sciences 25 (2008) 285–297 www.elsevier.com/locate/jsames

U–Pb ages of plutonic and metaplutonic rocks in southern Borborema Province (NE Brazil): Timing of Brasiliano deformation and magmatism

Se´rgio P. Neves a,*, Olivier Bruguier b, Delphine Bosch c, Jose´ Maurı´cio Rangel da Silva a, Gorki Mariano a

a Departamento de Geologia, Universidade Federal de , 50740-530 , Brazil b ISTEEM, Service ICP-MS, Universite´ de Montpellier II, 34095 Montpellier, France c Laboratoire de Tectonophysique, Universite´ de Montpellier II, 34095 Montpellier, France

Abstract

The Borborema Province of northeastern Brazil is divided into three main domains: northern, central, and southern. Several U–Pb zircon ages of plutons and orthogneisses became available in the recent years in the central and northern domains, but similar results are scarce in the southern domain. This study reports U–Pb dates for single zircon grains from one orthogneiss (Jupi orthogneiss) and two plutons (Cachoeirinha syenitic pluton and Cabanas granite) south of the East Pernambuco shear zone system (EPSZ). The results provide geo- chronological constraints on the timing of deformation and magmatism in this part of the southern domain and allow correlations with the central domain. The Jupi orthogneiss was emplaced and deformed during development of the regional flat-lying foliation. A 206Pb/238U weighted apparent mean age of 606 ± 8 Ma is interpreted as the crystallization age of the protolith of the orthogneiss and consequently the age of high-grade Brasiliano metamorphism. The NNE-trending Cachoeirinha pluton is only locally affected by strike-slip deformation, whereas the ENE-trending Cabanas granite is intensely affected by deformation related to the EPSZ. The 587 ± 8 Ma and 573 ± 4 Ma ages of the Cachoeirinha pluton and Cabanas granite, respectively, bracket the main period of activity of the EPSZ. Tectonomagmatic activity in the study area is similar to the age of Brasiliano events in the central domain, north of the EPSZ. In addition, xenocrystic zircons in the Jupi orthogneiss and Cabanas granite are interpreted as inherited from Paleoprotero- zoic source rocks, suggesting the presence of widespread reworked old crust in the southern domain, similar to the central domain. These results support the idea that the central and southern domains belonged to the same crustal block before the onset of the Brasiliano orogeny. Ó 2007 Elsevier Ltd. All rights reserved.

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

Resumo

A Provı´ncia Borborema (Nordeste do Brasil) e´ dividida em treˆs grandes domı´nios: norte, central e sul. Va´rias datac¸o˜es U–Pb em zirca˜o foram adquiridas nos u´ltimos anos nos domı´nios norte e central, mas sa˜o escassas no domı´nio sul. Neste estudo sa˜o apresentadas idades U–Pb de zirco˜es de um ortognaisse (ortognaisse Jupi) e de dois plutons (Cachoeirinha, de composic¸a˜o sienı´tica, e Cabanas, de compos- ic¸a˜o granı´tica) localizados ao sul da zona de cisalhamento Pernambuco leste (ZCPE). Estes resultados sa˜o os primeiros a serem reporta- dos para eventos deformacionais e magma´ticos nesta parte do domı´nio sul e permitem estabelecer correlac¸o˜es com o domı´nio central ao norte da ZCPE. O ortognaisse Jupi foi alojado e deformado durante o desenvolvimento da foliac¸a˜o regional de baixo aˆngulo. Uma idade media 206Pb/238U de 606 ± 8 Ma e´ interpretada como a idade de cristalizac¸a˜o do proto´lito do ortognaisse e, consequentemente, do

* Corresponding author. Tel.: +55 081 327 18240; fax: +55 081 327 18 234. E-mail address: [email protected] (S.P. Neves).

0895-9811/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.jsames.2007.06.003 286 S.P. Neves et al. / Journal of South American Earth Sciences 25 (2008) 285–297 metamorfismo Brasiliano. O pluton Cachoeirinha, de direc¸a˜o NNE-SSW, e´ afetado por deformac¸a˜ona˜o-coaxial apenas localmente, enquanto o Cabanas, de direc¸a˜o ENE-WNW, e´ fortemente deformado na sua porc¸a˜o norte pela ZCPE. As idades de 587 ± 8 Ma e 573 ± 4 Ma destes dois plutons limitam o perı´odo principal de funcionamento da ZCPE. A atividade termotectoˆnica na a´rea estudada e´ similar a` idade de eventos brasilianos no domı´nio central ao norte da ZCPE. Adicionalmente, populac¸o˜es de xenoc- ristais de zirca˜o no ortognaisse Jupi e no Granito Cabanas herdadas de fontes Paleoproterozo´icas sugerem a presenc¸a no domı´nio sul de extensas a´reas antigas retrabalhadas, similarmente ao observado no domı´nio central. Estes resultados indicam que os domı´nios central e sul pertenciam ao mesmo bloco crustal antes do inı´cio da orogeˆnese Brasiliana. Ó 2007 Elsevier Ltd. All rights reserved.

Palavras-chave: ICP-MS; Geocronologia U–Pb; Zirca˜o; Plutons neoproterozo´icos; Orogeˆnese Brasiliana

1. Introduction MS) zircon U–Pb ages of two plutons and one orthogneiss south of the East Pernambuco shear zone system (EPSZ), The Neoproterozoic evolution of Borborema Province which is conventionally taken as the limit between the (NE Brazil) is still a contentious issue, with contrasting central and southern domains in the eastern part of the models for the tectonic setting in which magmatic and Borborema Province. These are the first U–Pb zircon ages deformational events occurred. In particular, the signifi- reported so far for this portion of the southern domain. cance of the Cariris Velhos event and whether the Brasil- Along with available structural information (Neves iano orogeny took place in an intracontinental setting et al., 2003, 2005), they provide well-constrained age have been debated. The Cariris Velhos event was defined limits for the main period of tectonic activity related to in the central domain of the Borborema Province follow- the Brasiliano orogeny and shed new light on the age of ing the recognition of a metavolcanosedimentary belt with basement rocks underlying the study area. In addition, intercalated orthogneisses of early Neoproterozoic age we compare our new data with recently published data (Brito Neves et al., 1995). For a group of workers, this pertaining to north of the EPSZ (Brito Neves et al., belt formed as a consequence of a complete orogenic 2001; Guimara˜es et al., 2004; Neves et al., 2006) to evalu- cycle. They also suggested the possibility that this oro- ate possible correlations between the central and southern genic event affected other portions of the Borborema domains. Province, mainly in its southern domain (Brito Neves et al., 1995, 2000; Kozuch, 2003). Conversely, others con- 2. Geological setting sider that the belt where the Cariris Velhos event has been recorded was a continental rift intruded by intraplate 2.1. Previous geochronological work granites, with deformation and metamorphism only occur- ring during the Brasiliano orogeny (Neves, 2003; Gui- The geology of the southern domain south of the EPSZ mara˜es and Brito Neves, 2004; Neves et al., 2004). (Fig. 1) is dominated by high-grade, commonly migmatitic Regarding the geodynamic evolution of the Borborema orthogneisses and metasedimentary rocks and numerous Province during the Neoproterozoic, again two opposing large igneous intrusions. Orthogneisses and supracrustal views compete. In one model, the Borborema Province is rocks are grouped, respectively, in the Bele´mdoSa˜o Fran- regarded as an accretionary orogen whose evolution cisco and Cabrobo´ complexes (Medeiros, 1998; Gomes, involved a collage of allochtonous terranes (Santos and 2001). Only a few geochronological data are available for Medeiros, 1999; Brito Neves et al., 2000; Santos et al., these units. Zircons from two samples of orthogneisses 2004). The other model proposes that intraplate tectonism wrapped by mylonites of the EPSZ, but still preserving a driven by far-field stresses reworked preexisting Archean– flat-lying foliation, have been dated by the Pb-evaporation Paleoproterozoic crust and younger sedimentary succes- method (Neves et al., 2004). One sample, a medium- sions deposited dominantly in continental basin settings grained quartz dioritic gneiss, yields an age of (Neves, 2003; Neves et al., 2004, 2006). 2075 ± 7 Ma, interpreted as the crystallization age of the Geochronological data together with conventional field protolith of the orthogneiss during the Transamazonian and petrologic studies are required to tackle these contro- event. The other, a coarse-grained granitic gneiss ( versies. Numerous U–Pb ages of plutons and orthogneis- orthogneiss; Fig. 1), yields a Neoproterozoic age of ses became available in recent years in the central and 629 ± 9 Ma, indicating the existence of a flat-lying, folia- northern domains (see reviews by Brito Neves et al., tion-forming event during the Brasiliano orogeny. 2000; Neves, 2003; Neves et al., 2006). Similar results 40Ar/39Ar biotite ages around 560 Ma were obtained for are scarce in the southern domain, and their acquisition one pluton and a peraluminous orthogneiss (Osako, is essential to compare tectonomagmatic events at a prov- 2005). These ages are older than 40Ar/39Ar biotite ages ince-wide scale. In this paper, we report laser ablation from granitic mylonites in the EPSZ and in plutons and inductively coupled plasma-mass spectrometry (LA-ICP- country rocks north of the EPSZ (545–533 Ma; Neves S.P. Neves et al. / Journal of South American Earth Sciences 25 (2008) 285–297 287

Fig. 1. Sketch map of Borborema Province showing the main transcurrent shear zones and its division into northern (ND), central (CD), and southern (SD) domains, with location of study area south of the East Pernambuco shear zone system (EPSZ). The main map shows the main geological units of the study area and location of dated samples.

et al., 2000), which indicates that regional cooling to tion of juvenile material occurred during Mesoproterozoic around 300–350° (approximate closure temperature for and/or Neoproterozoic times. Ar diffusion in biotite; e.g., Dahl, 1996) in the southern domain was reached 15–25 Ma earlier than in the central 2.2. Study area domain. Nd isotope data also provide some time constraints for The study area comprises ortho- and paragneisses of the southern domain. Nd model ages of supracrustal and variable composition and several large igneous intrusions, migmatitic rocks yield mostly Paleoproterozoic–Archean two of which are considered herein: the Cachoeirinha plu- ages (2.0–2.6 Ga; Da Silva Filho et al., 2002; Osako, ton and the Cabanas granite (Fig. 1). Grey gneisses and 2005), but one Mesoproterozoic age (1.09 Ga) was migmatitic orthogneisses with mafic/intermediate proto- obtained for a sample of biotite gneiss (Da Silva Filho liths, interpreted as basement complexes, dominate in the et al., 2002). Most plutons also have Paleoproterozoic east. The small Caruaru orthogneiss, a biotite amphibole TDM ages, mainly between 1.8 and 2.2 Ga. However, one granitic gneiss, occurs south of the homonymous city and group of plutons yields distinctly younger Nd model ages, is distinguished from the grey gneisses by its coarse grain mainly between 1.5 and 1.0 Ga (Da Silva Filho et al., size, granitic composition, and usually lower strain. The 2002). These data suggest that a large part of the southern southern part of the study area is dominated by a granitic domain formed during the Paleoproterozoic but the addi- orthogneiss, here named the Jupi orthogneiss, which is 288 S.P. Neves et al. / Journal of South American Earth Sciences 25 (2008) 285–297

Fig. 2. (A) Field and (B,C) microstructural aspects in crossed polars of the Jupi orthogneiss. (A) Subhorizontal foliation containing a xenolith of flattened pelitic paragneiss. (B) Foliation defined by mica flakes and an elongate K-feldspar grain (left upper side) that probably represents a magmatic crystal that did not fully recrystallize during synmagmatic deformation. (C) Dominant granoblastic microstructure with polygonal aggregates of quartz, K-feldspar, and plagioclase typical of high-temperature recrystallization.

intruded by several small bodies of diorite and leucogra- contact between the Cabanas granite and the Cachoeirinha nite. In contrast with the grey gneisses, the Jupi orthogneiss pluton was not directly observed in the field. However, (1) is a leucocratic, generally muscovite-bearing biotite gneiss dikes of biotite granite and muscovite-bearing pegmatite, that locally contains a large amount of xenoliths of pelitic which might be genetically related to the Cabanas granite, paragneiss (Fig. 2A). These xenoliths are petrographically locally intrude the Cachoeirinha pluton and (2) the Caba- similar to micaschists and paragneisses that dominate the nas granite intrudes a granitic pluton that shows concor- western part of the study area and display the assemblage dant contacts with the Cachoerinha pluton. These biotite ± muscovite ± sillimanite + garnet + plagioclase + observations suggest the Cachoeirinha pluton is older than quartz. The Jupi orthogneiss presents a dominantly flat- the Cabanas granite. lying foliation that is cross-cut by a subvertical sinistral shear The Cachoeirinha pluton contains two main petro- zone in its western portion (Fig. 1). A flat-lying foliation is graphic facies: inequigranular to porphyritic biotite amphi- also dominant in the other metasedimentary and metaig- bole syenite and medium-grained biotite amphibole quartz neous units, away from shear zones and Brasiliano plutons. syenite. The biotite amphibole syenite is the most abundant The biotite–muscovite-bearing Cabanas granite, which facies and constitutes most of the northern and eastern crops out at the southern side of the EPSZ (Fig. 1), con- parts of the pluton. The biotite amphibole quartz syenite tains xenoliths of high-T granitic mylonites. These xeno- is mostly found in the central and southern parts of the plu- liths are similar to those that resulted from deformation ton. Magmatic foliation defined by the shape-preferred ori- of granitoids of the Caruaru– batholith in the entation of K-feldspar is visible in most outcrops of the northern branch of the EPSZ, indicating intrusion after biotite amphibole syenite, especially close to the margins, the onset of the activity in the EPSZ (Neves et al., 2003). with steep dips dominantly to ESE. Solid-state deforma- The ENE-trending shape of the Cabanas granite, together tion overprinting of the magmatic foliation is restricted in with the parallelism between magnetic foliations and linea- most places to weak deformation at high temperatures, as tions, obtained by anisotropy of magnetic susceptibility shown by chessboard extinction in quartz and development (AMS), inside the pluton and the mylonitic fabric of the of myrmekitic intergrowths around K-feldspar. Stronger EPSZ, indicates crystallization under the influence of the solid-state deformation occurs along meters to tens of dextral transcurrent regime (Neves et al., 2003). The meters long sinistral and dextral shear zones. Dextral and S.P. Neves et al. / Journal of South American Earth Sciences 25 (2008) 285–297 289 sinistral shear zones are consistently oriented NNE and ENE, respectively. These observations, in association with an AMS survey, are evidence that intrusion of the Cach- oeirinha pluton occurred during bulk NW–SE shortening, with zones of non-coaxial shear developing locally (Neves et al., 2005).

3. Studied samples

The Jupi orthogneiss sample presents, in thin section, a foliation defined mainly by biotite together with thin muscovite and subordinately by elongate grains of K-feld- spar and plagioclase (Fig. 2B and C). These elongate feld- spar grains indicate the igneous origin of the rock, but metamorphic recrystallization is extensive. A polygonal microstructure in which most feldspar and quartz grains meet at triple junctions dominates, indicating that solid- state recrystallization occurred at high temperature (Fig. 2C). Apart from zircon, apatite is the only prominent accessory, occurring as short prismatic crystals included or partially included in biotite and feldspars. Zircons extracted from this sample cluster in two distinct groups on the basis of their morphology, as observed by scanning electronic microscopy (SEM; Fig. 3). One population con- sists of euhedral to suhedral grains with preserved crystal faces and oscillatory zoning, typical of igneous crystalliza- tion (Fig. 3A). The other comprises equidimensional rounded grains and elongated grains with rounded corners, which are characteristics of detrital grains transported dur- ing sedimentary processes (Fig. 3B and C). The sample of the Cachoeirinha pluton chosen for geo- chronological work came from the biotite amphibole sye- nite facies. It contains large grains of amphibole and K- feldspar in an equigranular matrix composed of microcline, plagioclase, biotite, and minor quartz. Magnetite, sphene, zircon, and apatite occur as accessory phases. The zircons are elongated and present bipyramidal terminations typical of a magmatic growth (Fig. 4). The sample of the Cabanas granite was deformed by strike-slip shearing and displays microstructural features typical of mylonites deformed at intermediate temperature conditions, with porphyroclasts of K-feldspar and plagioclase wrapped by quartz, musco- vite and biotite. Zircon and apatite are the only accessory phases. No SEM images are available for zircons of this sample.

4. Analytical techniques Fig. 3. SEM images of selected dated zircon grains of the Jupi orthogneiss sample showing position of the LA-ICP-MS spots (spot size 25 lm) and Zircons were separated using conventional techniques. corresponding ages (errors quoted at the 2r level). (A) Euhedral zircon After crushing and sieving of the powdered samples, heavy with faint oscillatory zoning representative of the dominant population. minerals were concentrated by panning and then by heavy (B) Elongate zircon with rounded corners. (C) Equidimensional anhedral liquids. The heavy mineral concentrates were subsequently zircon. processed by magnetic separation on a Frantz separator. Zircon grains were hand picked from the non-magnetic et al., 1995), and polished to about half of their thickness. fraction at 1.5 A˚ intensity and 2° side tilt. The grains were U–Pb data were acquired at the University of Montpellier then mounted on adhesive tape, enclosed in epoxy resin II using a 1991 vintage VG Plasmaquad II turbo ICP-MS with chips of a standard material (G91500; Wiedenbeck coupled with a Geolas (Microlas) automated platform 290 S.P. Neves et al. / Journal of South American Earth Sciences 25 (2008) 285–297

ratio (0.54–2.5; Table 1). Therefore, the weighted mean age is interpreted as the age of zircon crystallization from a melt (magmatic age) and, consequently, of the igneous protolith of the orthogneiss. Other analyses indicate old, Paleoproterozoic ages (Fig. 5c), among which six cluster close to concordia and yield a weighted 207Pb/206Pb mean age of 1980 ± 13 (MSWD = 1.5). The oldest grain analysed exhibits a 207Pb/206Pb age of 2108 ± 36 Ma. These ages were obtained on rounded zircon grains or elongated zircon grains with rounded corners. In both cases, the zircons have high Th/U ratios similar to magmatic ones. They are interpreted as xenocrysts inherited from the parent rock that melted to produce the protolith of the Jupi orthogneiss.

5.2. Cachoeirinha pluton and Cabanas granite

Analysed zircons from the sample of the Cachoeirinha pluton yield a weighted 206Pb/228U mean age of 587 ± 8 Ma (MSWD = 0.49; Fig. 6). The euhedral shape and high Th/U ratio (0.48–1.55; Table 1) of the grains indi- cate that this age must correspond to the zircon crystalliza- tion age and thus to the date of emplacement of the Cachoeirinha pluton. Analyses of zircon grains from the Cabanas granite lie on a discordia with an upper intercept of 2192 ± 14 Ma and a lower intercept of 570 ± 7 Ma (MSWD = 1.06; Fig. 7a). The lower intercept is anchored by 16 concordant analyses that yield a weighted 206Pb/228U mean age of 573 ± 4 (MSWD = 1.07; Fig. 7b), which is considered the Fig. 4. SEM images of selected dated zircon grains of the Cachoeirinha best estimate for the emplacement age of the intrusion. pluton sample showing position of the LA-ICP-MS spot (spot size 25 l) The upper intercept is interpreted as the average age of a and corresponding age (errors quoted at the 2r level). xenocrystic component derived from deep-seated source rock. One analysis at 3383 ± 30 Ma and another at 1560 ± 16 Ma suggest that the parent rock also included housing a 193 nm Compex 102 laser from LambdaPhysik. Archean and Mesoproterozoic components. Details of the analytical procedures and data reduction are described in Neves et al. (2006). 6. Discussion

5. Results 6.1. Brasiliano-age events

Table 1 shows the results of the analytical data for the The 606 ± 8 Ma age of the Jupi orthogneiss is consid- studied samples. Ages of zircons are expressed in terms ered to represent the crystallization of its granitic proto- of either their 207Pb/206Pb ratios (grains older than 1 Ga) lith. Together with the high-temperature gneissic fabric, or their 206Pb/238U ratios (grains with Neoproterozoic this age is taken as evidence that the Jupi orthogneiss ages). Errors for single analysis and mean ages are quoted was a synkinematic intrusion emplaced during a high- at the 2r level. grade tectonic event. Likewise, the 629 ± 9 Ma age of the Caruaru orthogneiss (Neves et al., 2004) is interpreted 5.1. Jupi orthogneiss as dating the emplacement of its granitic protolith. Intru- sion of the protoliths of both the Caruaru orthogneiss Analyses of zircons from the studied sample of the Jupi and the Jupi orthogneiss clearly predates the development orthogneiss cluster into two age groups (Fig. 5a). Seventeen of transcurrent shear zones, because strike–slip-related of the analyzed grains plot close to the concordia and yield mylonitic belts truncate their subhorizontal fabric (Neves a 206Pb/238U weighted apparent mean age of 606 ± 8 Ma et al., 2004). Considering that the structure in these two (MSWD = 0.64; Fig. 5b). These grains are euhedral, con- rock units parallels that present in migmatized metasedi- tain oscillatory magmatic zoning, and have high Th/U mentary rocks and grey orthogneisses, we propose that Table 1 U–Th–Pb LA-ICP-MS results for zircon grains from plutonic bodies of the southern domain of Borborema Province (Brazil) Sample Pb (ppm) U (ppm) Th (ppm) Th/U 208Pb/206Pb 207Pb/206Pb ± (1s) 207Pb/235U ± (1s) 206Pb/238U ± (1s) Rho Apparent ages (Ma) 206Pb/238U ± (1s) 207Pb/206Pb ± (1s) Cachoeirinha pluton sc4* 23 185 200 1.08 0.375 0.0623 0.0030 0.7985 0.0531 0.0929 0.0043 0.70 573 25 686 102 sc33* 52 540 257 0.48 0.165 0.0619 0.0016 0.7957 0.0258 0.0932 0.0019 0.64 574 11 672 54 sc15* 60 575 425 0.74 0.227 0.0608 0.0006 0.7822 0.0243 0.0933 0.0028 0.95 575 16 631 20 sc40* 43 415 232 0.56 0.218 0.0642 0.0034 0.8272 0.0462 0.0934 0.0017 0.32 575 10 750 112 ..Nvse l ora fSuhAeia at cecs2 20)285–297 (2008) 25 Sciences Earth American South of Journal / al. et Neves S.P. sc32* 19 138 133 0.97 0.465 0.0652 0.0024 0.8544 0.0882 0.0950 0.0092 0.94 585 54 782 76 sc31* 22 184 200 1.08 0.357 0.0594 0.0012 0.7789 0.0301 0.0951 0.0032 0.86 586 19 581 43 sc36* 36 250 156 0.62 0.444 0.0617 0.0038 0.8100 0.0578 0.0951 0.0035 0.52 586 21 665 131 sc18* 58 528 465 0.88 0.251 0.0630 0.0015 0.8288 0.0416 0.0954 0.0042 0.88 587 25 710 51 sc3* 26 196 304 1.55 0.448 0.0656 0.0011 0.8688 0.0609 0.0960 0.0066 0.97 591 38 795 34 sc9* 23 187 286 1.53 0.442 0.0618 0.0012 0.8226 0.0289 0.0966 0.0028 0.83 594 16 666 42 sc8* 60 518 376 0.73 0.234 0.0607 0.0019 0.8131 0.0302 0.0971 0.0020 0.56 597 12 630 66 sc19* 65 599 555 0.93 0.252 0.0617 0.0030 0.8281 0.0535 0.0974 0.0041 0.65 599 24 663 106 sc38* 53 482 357 0.74 0.251 0.0610 0.0027 0.8195 0.0622 0.0974 0.0060 0.81 599 35 639 95 sc6* 27 221 199 0.90 0.297 0.0621 0.0026 0.8376 0.0412 0.0977 0.0025 0.51 601 14 679 90 sc24* 44 406 235 0.58 0.184 0.0641 0.0013 0.8663 0.0288 0.0980 0.0025 0.78 603 15 745 44 sc10 10 85 76 0.88 0.244 0.0624 0.0006 0.8922 0.0177 0.1037 0.0018 0.89 636 11 688 19 Mean = 586.6 ± 8.4 [1.4%] 95% conf. Wtd by data-pt errs only, 1 of 16 rej. MSWD = 0.49, probability = 0.94

Jupi orthogneiss sb15 9 90 202 2.25 0.394 0.0590 0.0010 0.6430 0.0115 0.0790 0.0004 0.30 490 3 567 37 sb11* 5 40 48 1.19 0.354 0.0631 0.0014 0.8355 0.0288 0.0961 0.0026 0.78 591 15 711 46 sb20* 6 61 33 0.54 0.254 0.0593 0.0011 0.7902 0.0295 0.0966 0.0031 0.87 595 18 578 40 sb29* 8 61 96 1.57 0.481 0.0590 0.0022 0.8345 0.0438 0.1025 0.0038 0.7 629 22 568 82 sb18* 5 42 41 0.98 0.323 0.0640 0.0028 0.8030 0.0505 0.0910 0.0042 0.73 561 25 742 91 sb6* 3 25 38 1.49 0.378 0.0582 0.0025 0.7917 0.0423 0.0987 0.0032 0.61 607 19 536 92 sb13* 3 26 31 1.18 0.371 0.0607 0.0025 0.8234 0.0429 0.0984 0.0032 0.62 605 19 629 88 sb7* 4 30 51 1.71 0.394 0.0622 0.0002 0.8104 0.0298 0.0945 0.0035 1.00 582 20 680 7 sb23* 3 27 26 0.97 0.343 0.0611 0.0015 0.8493 0.0332 0.1007 0.0031 0.78 619 18 644 53 sb10* 6 55 62 1.14 0.335 0.0609 0.0021 0.8295 0.037 0.0989 0.0029 0.65 608 17 634 73 sb16* 7 63 78 1.24 0.412 0.0618 0.0013 0.8157 0.0381 0.0957 0.0040 0.88 589 23 668 46 sb5* 5 46 45 0.97 0.252 0.0596 0.0023 0.8159 0.042 0.0993 0.0034 0.67 610 20 589 82 sb8* 10 79 122 1.53 0.431 0.0640 0.0014 0.8400 0.0504 0.0953 0.0053 0.93 587 31 740 45 sb12* 16 118 213 1.81 0.532 0.0606 0.0010 0.8298 0.0226 0.0993 0.0022 0.82 610 13 625 34 sb24* 3 24 25 1.08 0.341 0.0642 0.0017 0.8842 0.0265 0.0999 0.0015 0.51 614 9 748 55 sb17* 4 34 50 1.44 0.433 0.0642 0.0022 0.9215 0.0657 0.1040 0.0065 0.87 638 38 750 73 sb14* 9 71 112 1.57 0.414 0.0601 0.0011 0.8171 0.0267 0.0986 0.0027 0.84 606 16 608 38 sb45* 42 315 520 1.65 0.576 0.0613 0.0011 0.8488 0.0542 0.1005 0.0062 0.96 617 36 649 38 sb19 15 106 185 1.74 0.508 0.0624 0.0017 0.9275 0.0318 0.1078 0.0023 0.61 660 13 688 58 (continued on next page) 291 Table 1 (continued) 292 Sample Pb (ppm) U (ppm) Th (ppm) Th/U 208Pb/206Pb 207Pb/206Pb ± (1s) 207Pb/235U ± (1s) 206Pb/238U ± (1s) Rho Apparent ages (Ma) 206Pb/238U ± (1s) 207Pb/206Pb ± (1s)

Mean = 605.7 ± 8.3 [1.4%] 95% conf. Wtd by data-pt errs only, 2 of 19 rej. MSWD = 0.64, probability = 0.85 sb32 22 71 63 0.88 0.287 0.1206 0.0014 4.2668 0.0714 0.2566 0.0032 0.73 1472 16 1965 20 sb22 60 186 103 0.56 0.163 0.1208 0.0009 4.8631 0.1584 0.2919 0.0093 0.98 1651 46 1968 13 sb31 157 438 230 0.52 0.154 0.1178 0.0006 5.2940 0.0759 0.3258 0.0044 0.94 1818 21 1924 9 sb21 150 370 318 0.86 0.244 0.1223 0.0008 5.7271 0.2520 0.3396 0.0148 0.99 1885 71 1990 11 #

sb9 171 389 416 1.07 0.301 0.1209 0.0005 5.7316 0.1800 0.3440 0.0107 0.99 1906 51 1969 285–297 7 (2008) 25 Sciences Earth American South of Journal / al. et Neves S.P. sb33# 66 172 103 0.60 0.190 0.1232 0.0008 5.9513 0.1774 0.3503 0.0102 0.97 1936 48 2003 12 sb2# 189 453 409 0.90 0.258 0.1217 0.0006 5.9896 0.2679 0.3571 0.0159 0.99 1968 75 1981 8 sb30# 158 364 265 0.73 0.231 0.1212 0.0013 6.0052 0.1175 0.3594 0.0059 0.84 1979 28 1974 19 sb42 101 250 159 0.63 0.093 0.1307 0.0014 6.5551 0.3149 0.3637 0.0170 0.98 1999 80 2108 18 sb36# 182 465 118 0.25 0.094 0.1232 0.0015 6.1800 0.0903 0.3638 0.0028 0.54 2000 13 2003 22 sb1# 214 475 431 0.91 0.282 0.1218 0.0008 6.2267 0.2792 0.3708 0.0165 0.99 2033 77 1983 11 Mean = 1980 ± 13 [0.68%] 95% conf. Wtd by data-pt errs only, 0 of 6 rej. MSWD = 1.5, probability = 0.19

Cabanas granite yb13* 20 218 104 0.47 0.131 0.0591 0.0005 0.7297 0.012 0.0896 0.0013 0.85 553 7 570 19 yb4* 19 194 116 0.60 0.164 0.0582 0.0007 0.7350 0.0128 0.0915 0.0012 0.73 565 7 539 26 yb6* 16 161 77 0.48 0.136 0.0607 0.0013 0.7681 0.0187 0.0917 0.0011 0.48 566 6 629 46 yb25* 33 370 61 0.16 0.067 0.0614 0.0039 0.7812 0.0582 0.0923 0.0036 0.53 569 21 652 136 yb29* 87 711 1253 1.76 0.511 0.0621 0.0011 0.7949 0.0425 0.0929 0.0047 0.94 573 28 676 38 yb26* 17 177 85 0.48 0.151 0.0623 0.0033 0.7981 0.0422 0.0930 0.0007 0.13 573 4 683 112 yb10* 19 187 80 0.43 0.189 0.0597 0.0018 0.7696 0.0256 0.0936 0.0012 0.38 577 7 591 67 yb3* 19 192 68 0.36 0.137 0.0579 0.0004 0.7484 0.0121 0.0937 0.0014 0.9 578 8 526 15 yb23* 27 274 125 0.46 0.144 0.0591 0.0012 0.7651 0.0285 0.0938 0.0029 0.84 578 17 572 44 yb5* 39 435 77 0.18 0.049 0.0595 0.0005 0.7701 0.0204 0.0939 0.0024 0.94 579 14 585 19 yb27* 17 164 111 0.68 0.189 0.0630 0.0012 0.8179 0.0211 0.0941 0.0016 0.66 580 9 710 41 yb20* 21 212 133 0.63 0.187 0.0610 0.0006 0.7939 0.0158 0.0944 0.0016 0.87 581 10 639 21 yb22* 20 200 86 0.43 0.127 0.0590 0.0005 0.7679 0.0163 0.0944 0.0019 0.92 582 11 566 18 yb24* 36 385 71 0.18 0.054 0.0587 0.0003 0.7673 0.0173 0.0947 0.0021 0.97 583 12 558 12 yb21* 24 246 111 0.45 0.143 0.0600 0.0004 0.7887 0.0161 0.0954 0.0018 0.93 587 11 603 16 yb28* 64 614 137 0.22 0.166 0.0628 0.0016 0.8346 0.0385 0.0964 0.0037 0.83 593 22 701 54 yb9 21 60 78 1.30 0.352 0.0966 0.0004 3.6300 0.0988 0.2725 0.0073 0.99 1553 37 1560 8 yb8 99 290 393 1.36 0.386 0.1230 0.0013 4.4349 0.0495 0.2614 0.0010 0.36 1497 5 2001 19 yb11 54 161 16 0.10 0.051 0.1326 0.0006 6.0751 0.0669 0.3323 0.0033 0.92 1849 16 2133 8 yb1 72 190 48 0.25 0.082 0.1345 0.0006 6.6649 0.1332 0.3594 0.007 0.98 1979 33 2158 7 yb2 64 160 40 0.25 0.092 0.1338 0.0012 6.8821 0.1262 0.3731 0.0059 0.87 2044 28 2148 16 yb30 45 110 31 0.28 0.167 0.1547 0.0027 7.6944 0.1647 0.3608 0.0045 0.58 1986 21 2398 30 yb7 132 161 65 0.40 0.120 0.2836 0.0028 26.3895 0.4727 0.6749 0.0101 0.83 3325 39 3383 15 Mean = 572.7 ± 4.1 [0.72%] 95% conf. Wtd by data-pt errs only, 0 of 16 rej. MSWD = 1.07, probability = 0.37 Note: For each rock, ages have been calculated on the basis of 206Pb/238U weighted averages from data labelled *. For the Jupi orthogneiss, the Paleoproterozoic age has been calculated on the basis of 207Pb/206Pb weighted averages from data labeled #. S.P. Neves et al. / Journal of South American Earth Sciences 25 (2008) 285–297 293

0.12 720 U Cachoeirinha pluton 238 (Borborema Province, Brazil) Pb/ 680 206 0.11

640

0.10 600

560 206 238 0.09 Pb/ U weighted mean: 587±8 Ma (n = 15) MSWD=0.49 520 207Pb/235U 0.08 0.65 0.75 0.85 0.95 1.05

Fig. 6. U–Pb concordia diagram for zircons from the Cachoeirinha pluton.

the extensive migmatization is coeval with the develop- ment of the regional flat-lying fabrics in orthogneisses and supracrustal rocks, formed during the Brasiliano orogeny. Therefore, these data allow the timing of this tectonic phase of the Brasiliano orogeny to be broadly constrained to the time span 630–600 Ma. The 587 ± 8 Ma and 573 ± 4 Ma ages of the Cachoeir- inha pluton and Cabanas granite, respectively, are consis- tent with field relationship and internal structures in these intrusions, which suggest that the Cachoeirinha pluton is older than the Cabanas granite (Neves et al., 2005). The lack of large mylonitic zones in the Cachoeirinha pluton and its NNE-trending orientation indicate that it was not intensely affected by strike–slip-related deformation. This indication suggests that its intrusion occurred at the beginning of the transcurrent regime that produced the dextral EPSZ and associated sinistral shear zones. In contrast, the presence of mylonitic xenoliths and exten- sive mylonitization of the Cabanas granite along its northern side indicate that its intrusion took place when the transcurrent regime was fully established (Neves et al., 2003). Theexistingdatarevealthatthemainphaseoftec- tonomagmatic activity in the study area lasted from 630 to 570 Ma, with a first phase of low-angle tectonics, fol- lowed by strike–slip shearing. The ages of the Cachoeirin- ha pluton and Cabanas granite can be interpreted as indicating that deformation associated with the EPSZ is 20–30 Ma younger than that responsible for the regional Fig. 5. (a) U–Pb concordia diagram for zircons from Jupi orthogneiss flat-lying foliation. However, at the present time, it is sample (b) Zoom showing the weighted mean age of 17 Neoproterozoic zircon analyses. (c) Zoom of Paleoproterozoic zircons showing the not yet unequivocal whether there was a progressive weighted mean age of 6 zircon analyses. change from one regime to the other or if they are discrete 294 S.P. Neves et al. / Journal of South American Earth Sciences 25 (2008) 285–297

imentary rock itself had a strong inflow of sediments U Cabanas Granite derived from an igneous source with this age. 0.4 238 2000 Similar to the Jupi orthogneiss, the two-mica Cabanas Pb/ granite also contains a xenocrystic population of zircons, 206 most likely inherited from its source rock. However, in this 0.3 1560±16 Ma 1600 case, the parent rock was derived predominantly from an older source, as is indicated by the upper intercept age of

One analysis at approximately 2.2 Ga. The data do not allow us to con- 1200 3383±30 Ma 0.2 clude whether the Cabanas granite and Jupi orthogneiss were derived from anatexis of different sedimentary Discordia line with Upper intercept: 2192±14 Ma sequences or formed by partial melting from different crus- 800 Lower intercept: 570±7 Ma tal levels within the same rock package. In any case, they (MSWD = 1.06) 0.1 substantiate the presence of a Paleoproterozoic basement 400 south of the EPSZ. 207Pb/235U 0.0 6.3. Correlations with the central domain 02 4 68 The occurrence of Transamazonian basement (2.2– 0.104 2.0 Ga) is well documented in the central domain north Cabanas Granite

U of the EPSZ (Brito Neves et al., 2001; Neves et al., 2004,

238 620 2006)(Fig. 8 and Table 2). It is also suggested in the south-

0.100 Pb/ ern domain by Sm–Nd isotopic data from plutons and 206 country rocks (Da Silva Filho et al., 2002; Osako, 2005) 600 and now confirmed by the age of inherited zircons in the

0.096 Jupi orthogneiss and Cabanas granite. Orthogneisses have ages mostly in the range 1.97–2.13 Ga and are considered 580 the basement for younger igneous, metaigneous, and metasedimentary rocks (Sa´ et al., 2002; Neves et al., 0.092 560 206Pb/238U weighted mean: 2004, 2006). The 1.7–1.5 Ga granitic gneisses and meta- 573±4 Ma (n = 16) anorthosites (Fig. 8 and Table 2) that are also found in MSWD = 1.07 the central domain and interpreted as anorogenic intru- 0.088 540 sions emplaced after the Transamazonian orogeny (Accioly et al., 2000; Sa´ et al., 2002). It is perhaps significant that 207 235 Pb/ U one zircon grain in the Cabanas granite yielded an age of 520 0.084 1560 ± 16 Ma, which opens up the possibility that rocks 0.60 0.70 0.80 0.90 1.00 1.10 of this age can also be identified in the southern domain. Fig. 7. (a) U–Pb concordia diagram for zircons from the Cabanas granite. Suggestions that an early Neoproterozoic orogeny (Car- (b) Zoom showing the weighted mean age of 16 Neoproterozoic zircon iris Velhos event) affected the southern portion of the Bor- analyses. borema province (Brito Neves et al., 1995, 2000; Kozuch, 2003) are not supported by this study. Also, in the central episodes temporarily separated. Lack of ages in the time domain, lower intercept ages in concordia diagrams from interval 605–590 Ma may be due simply to the absence several samples of orthogneisses only point to an important of suitable lithologies (paucity of magmatism) or deficient tectonothermal event during the late Neoproterozoic Bra- knowledge. siliano orogeny (Brito Neves et al., 2001; Santos et al., 2004; Neves et al., 2006). Dating of magmatic and meta- morphic zircons north of the EPSZ yields ages in the range 6.2. Evidence for Paleoproterozoic basement 630–610 Ma (Neves et al., 2006), indicating that high-grade metamorphism was roughly synchronous with that in the The mineralogy, presence of xenoliths of pelitic parag- southern domain. neiss, and a xenocrystic zircon population in the Jupi Brasiliano intrusive rocks can be classified according to orthogneiss suggest that its protolith was produced by par- their relationships with transcurrent shear zones that tial melting of metasedimentary rocks. The Paleoprotero- transect this region as prekinematic, early-kinematic, and zoic xenocrystic zircon population consists of rounded syn- to late-kinematic. In the southern domain, they corre- grains, whose abundance makes it unlikely they were spond, respectively, to the Caruaru and Jupi orthogneisses, derived through assimilation of country rocks. The high the Cachoeirinha pluton, and the Cabanas granite. The Th/U ratio (0.25–1.07; Table 1) of grains that yield a mean ages of these three groups of rocks closely agree with equiv- age of approximately 1.98 Ga suggests that the source sed- alent groups in the central domain. An increasing number S.P. Neves et al. / Journal of South American Earth Sciences 25 (2008) 285–297 295

Fig. 8. Simplified geological map of eastern Borborema Province showing available geochronological U–Pb and Pb–Pb ages for igneous and metaigneous rocks. All ages are U–Pb zircon ages in Ma except that labeled 1.58–168 Ga (Mo), which corresponds to monazite ages in Ga. Sources of data: Accioly et al. (2000), Sa´ et al. (2002), Guimara˜es et al. (2004), Neves et al. (2004), Neves et al. (2006), this work. of pre-transcurrent plutons with ages between 620 and aru and Jupi orthogneisses (629 Ma and 606 Ma, respec- 645 Ma have been recognized in the central domain (Brito tively) in the south. The most voluminous magmatism in Neves et al., 2003; Guimara˜es et al., 2004), indicating that the central domain is represented by intrusions spatially the thermal anomaly responsible for partial melting and associated with strike-slip shear zones with ages mainly in granite intrusion that affected this area is of approximately the range 592–585 Ma (Guimara˜es and Da Silva Filho, the same age as the intrusion of the protoliths of the Caru- 1998; Brito Neves et al., 2003; Neves et al., 2004; Guimara˜es

Table 2 Summary of available geochronological data for igneous and metaigneous rocks in eastern Borborema Province Rock type or unit Mineral Age (Ma) Method Reference Banded orthogneiss Zircon 2125 ± 7 U–Pb (LA-ICP-MS) Neves et al. (2006) Metagranodiorite Zircon 2097 ± 5 U–Pb (LA-ICP-MS) Neves et al. (2006) Diotitic orthogneiss Zircon 2098 ± 15 Pb–Pb evaporation Neves et al. (2004) Diotitic orthogneiss Zircon 2075 ± 7 Pb–Pb evaporation Neves et al. (2004) Granitic gneiss Zircon 2072 ± 8 Pb–Pb evaporation Neves et al. (2004) Granitic gneiss Zircon 1991 ± 5 U–Pb (LA-ICP-MS) Neves et al. (2006) Granodioritic orthogneiss Zircon 1974 ± 32 U–Pb (convencional) Sa´ et al. (2002) Meta-anorthosite Zircon 1718 ± 19 U–Pb (convencional) Accioly et al. (2000) Granitic gneiss Monazite 1680 ± 100 U–Th–Pb (ion microprobe) Accioly et al. (2000) Granitic gneiss Monazite 1640 ± 90 U–Th–Pb (ion microprobe) Accioly et al. (2000) Granitic gneiss Zircon 1580 ± 90 U–Th–Pb (ion microprobe) Accioly et al. (2000) Augen gneiss Zircon 1521 ± 6 U–Pb (convencional) Sa´ et al. (2002) Timbau´ba pluton Zircon 645 ± 5 U–Pb (convencional) Guimara˜es et al. (2004) Caruaru orthogneiss Zircon 629 ± 9 Pb–Pb evaporation Neves et al. (2004) Migmatite leucosome Zircon 626 ± 15 U–Pb (LA-ICP-MS) Neves et al. (2006) Jupi orthogneiss Zircon 606 ± 8 U–Pb (LA-ICP-MS) This study Bom Jardim pluton Zircon 592 ± 7 U–Pb (convencional) Guimara˜es et al. (2004) Caruaru–Arcoverde batholith Zircon 591 ± 5 Pb–Pb evaporation Neves et al. (2004) Caruaru–Arcoverde batholith Zircon 588 ± 12 U–Pb (convencional) Guimara˜es et al. (2004) Caruaru–Arcoverde batholith Zircon 587 ± 5 Pb–Pb evaporation Neves et al. (2004) Cachoeirinha pluton Zircon 587 ± 8 U–Pb (LA-ICP-MS) This study Cabanas Granite Zircon 573 ± 4 U–Pb (LA-ICP-MS) This study Queimadas pluton Zircon 570 ± 24 U–Pb (convencional) Guimara˜es et al. (2004) 296 S.P. Neves et al. / Journal of South American Earth Sciences 25 (2008) 285–297 et al., 2004), which overlap the age (587 Ma) of the References Cachoeirinha pluton. Plutons emplaced at the advanced stages of shear zone development in the central domain Accioly, A.C.A., McReath, I., Santos, E.J., Guimara˜es, I.P., Vannuci, R., (Almeida et al., 2002; Guimara˜es et al., 2004) are similar Bottazzi, R., 2000. The meta-anorthositic complex and its tectonic implication, Borborema Province, Brazil. 31° International in age (575–570 Ma) to the Cabanas granite (Table 2). Geological Congress. International Union of Geological Sciences, Taken together, these results support the proposal that Abstracts, Rio de Janeiro. the central and southern domains underwent similar tec- Almeida, C.N., Guimara˜es, I.P., Da Silva Filho, A.F., 2002. A-type post- tonothermal evolution during most of the Proterozoic collisional granites in the Borborema province - NE Brazil: the eon. This finding weakens arguments in favor of an evolu- Queimadas pluton. Gondwana Research 5, 667–681. Brito Neves, B.B., Van Schmus, W.R., Santos, E.J., Campos Neto, M.C., tion involving collage of allochtonous terranes (Santos and Kozuch, M., 1995. O evento Cariris Velhos na Provı´ncia Borborema: Medeiros, 1999; Brito Neves et al., 2000; Santos et al., integrac¸a˜o de dados, implicac¸o˜es e perspectivas. Revista Brasileira de 2004). Although it could be argued that previously sepa- Geocieˆncias 25, 279–296. rated blocks underwent similar geologic histories before Brito Neves, B.B., Santos, E.J., Van Schmus, W.R., 2000. Tectonic convergence and collision, it is unlikely. No evidence for history of the Borborema province. In: Cordani, U.G., Milani, E.J., Thomaz Filho, A., Campos, D.A. (Eds.), Tectonic evolution of South petrotectonic assemblages typical of subduction zone envi- America. 31° International Geological Congress, Rio de Janeiro, pp. ronments and suture zones have been documented, and the 151-182. EPSZ is not a terrane boundary. Instead, detailed struc- Brito Neves, B.B., Campos Neto, M.C., Van Schmus, W.R., Fernandes, tural study shows that the EPSZ is a relatively late Brasil- T.M.G., Souza, S.L., 2001. O terreno Alto Moxoto´ no leste da Paraı´ba iano feature developed in an intracontinental setting (Macic¸o Caldas Branda˜o). Revista Brasileira de Geocieˆncias 31, 185– 194. (Neves et al., 1996, 2000). Therefore, the southern and cen- Brito Neves, B.B., Passarelli, C.R., Basei, M.A.S., Santos, E.J., 2003. tral domains probably belonged to the same crustal block Idades U–Pb em zirca˜o de alguns granitos cla´ssicos da Provı´ncia before the onset of the Brasiliano orogeny. Borborema. Geologia USP: Se´rie Cientı´fica 3, 25–38. Da Silva Filho, A.F., Guimara˜es, I.P., Van Schmus, W.R., 2002. Crustal evolution of the Pernambuco-Alagoas complex, Borborema Province, NE Brazil: Nd isotopic data from Neoproterozoic granitoids. Gondw- 7. Conclusions ana Research 5, 409–422. Dahl, P.S., 1996. The crystal-chemical basis for Ar retention in micas: inferences from interlayer partitioning and implications for geochro- This study presents the first U–Pb zircon results for the nology. Contributions to Mineralogy and Petrology 123, 22–30. southern domain of the Borborema Province south of the Gomes, H.A., 2001. Geologia e Recursos Minerais do Estado de EPSZ and places important age limits on the tectonomag- Pernambuco. Ministe´rio de Minas e Energia. Secretaria de Minas e matic evolution of this region. The 606 ± 8 Ma age of the Metalurgia, CPRM – Servic¸o Geolo´gico do Brasil, 127 p. Jupi orthogneiss dates the peak of high-grade Brasiliano Guimara˜es, I.P., Brito Neves, B.B., 2004. Geochemistry characterization of part of the Early Neoproterozoic plutonism in the Central metamorphism and, consequently, the regional low-angle Structural Domain of the Borborema Province, NE Brazil. 32 foliation. Together with structural data obtained in previ- International Geological Congress. International Union of Geological ous studies, the 587 ± 8 Ma and 573 ± 4 Ma crystalliza- Sciences, Firenze. tion ages of the Cachoeirinha pluton and Cabanas Guimara˜es, I.P., Da Silva Filho, A.F., 1998. Nd- and Sr-isotopic and U– granite, respectively, bracket the main period of activity Pb geochronologic constraints for the evolution of the shoshonitic Brasiliano Bom Jardim and complexes: evidence for a of the EPSZ. The occurrence of inherited zircon compo- Transamazonian enriched mantle under Borborema tectonic province, nents in the Jupi orthogneiss and Cabanas granite is evi- Brazil. International Geology Review 40, 500–527. dence for a widespread Paleoproterozoic crust in the Guimara˜es, I.P., Da Silva Filho, A.F., Almeida, C.N., Van Schmus, W.R., southern domain. These results are comparable to those Arau´jo, J.M.M., Melo, S.C., Melo, E.B., 2004. Brasiliano (Pan- found north of the EPSZ, which indicates these two African) granite magmatism in the Pajeu´-Paraı´ba belt, Northeast Brazil: an isotopic and geochronological approach. Precambrian domains underwent similar tectonothermal evolution Research 135, 23–53. during most of the Proterozoic eon. The existence of an Kozuch, M., 2003. Isotopic and trace element geochemistry of early orogenic event of early Neoproterozoic age and the Neoproterozoic gneissic and metavolcanic rocks in the Cariris Velhos hypothesis of terrane accretion are therefore not sup- Orogen of the Borborema Province, Brazil, and their bearing on ported by the available data. tectonic setting. PhD thesis, University of Kansas. Medeiros, V.C., 1998. Folha (SC.24-Y-B): integrac¸a˜o geolo´g- ica. CPRM, Recife, unpublished internal report, 22 p. Neves, S.P., 2003. Proterozoic history of the Borborema Province (NE Acknowledgments Brazil): correlations with neighboring cratons and Pan-African belts, and implications for the evolution of western Gondwana. Tectonics 22, 1031. doi:10.1029/2001TC00135. LA-ICP-MS analyses were conducted as part of post- Neves, S.P., Vauchez, A., Archanjo, C.J., 1996. Shear-zone controlled doctoral studies by SPN, financed by the Brazilian agency magma emplacement or magma-assisted nucleation of shear zones? Conselho Nacional de Desenvolvimento Cientı´fico e Tec- Insights from northeast Brazil. Tectonophysics 262, 349–365. nolo´gico (CNPq). Samples were collected during fieldwork Neves, S.P., Vauchez, A., Fe´raud, G., 2000. Tectono-thermal evolution, magma emplacement, and shear zone development in the Caruaru area funded by the Fundac¸a˜o de Amparo a` Cieˆncia e Tecnologia (Borborema Province, NE Brazil). Precambrian Research 99, 1–32. do Estado de Pernambuco (FACEPE). S.P. Neves et al. / Journal of South American Earth Sciences 25 (2008) 285–297 297

Neves, S.P., Arau´jo, A.M.B., Correia, P.B., Mariano, G., 2003. Magnetic Osako, L.S., 2005. Caracterizac¸a˜o geolo´gica da regia˜o situada entre as fabrics in the Cabanas Granite (NE Brazil): interplay between localidades de e Currais Novos (PE), porc¸a˜o centro-norte emplacement and regional fabrics in a dextral transpressive regime. do Complexo Pernambuco-Alagoas, Provı´ncia Borborema. PhD Journal of Structural Geology 25, 441–453. thesis, Universidade Federal de Pernambuco, Recife, 163 p. Neves, S.P., Melo, S.C., Moura, C.A.V., Mariano, G., Silva, J.M.R., Sa´, J.M., Bertrand, J.M., Leterrier, J., Macedo, M.H.F., 2002. Geochem- 2004. Zircon Pb–Pb geochronology of the Caruaru area, northeastern istry and geochronology of pre-Brasiliano rocks from the Transversal Brazil: temporal constraints on the Proterozoic evolution of Borbor- Zone, Borborema Province, Northeast Brazil. Journal of South ema Province. International Geology Review 46, 52–63. American Earth Sciences 14, 851–866. Neves, S.P., Mariano, G., Beltra˜o, B.B., Correia, P.B., 2005. Emplace- Santos, E.J., Medeiros, V.C., 1999. Constraints from granitic plutonism ment and deformation of the Cachoeirinha pluton (Borborema on Proterozoic crustal growth of the Transverse Zone, Borborema province, NE Brazil) inferred through petrostructural studies: Province, NE Brazil. Revista Brasileira de Geocieˆncias 29, 73–84. constraints on regional strain fields. Journal of South American Santos, E.J., Nutman, A.P., Brito Neves, B.B., 2004. Idades SHRIMP U– Earth Sciences 19, 127–141. Pb do Complexo Sertaˆnia: implicac¸o˜es sobre a evoluc¸a˜o tectoˆnica da Neves, S.P., Bruguier, O., Vauchez, A., Bosch, D., Silva, J.M.R., zona transversal, Provı´ncia Borborema. Geologia USP: Se´rie Cientı´- Mariano, G., 2006. Timing of crust formation, deposition of fica 4, 1–12. supracrustal sequences, and Transamazonian and Brasiliano meta- Wiedenbeck, M., Alle´, P., Corfu, F., Griffin, W.L., Meier, M., Oberli, F., morphism in eastern Borborema Province (NE Brazil): implications von Quadt, A., Ruddick, J.C., Spiegel, W., 1995. Three natural zircon for western Gondwana assembly. Precambrian Research 149, 197– standards for U–Th–Pb, Lu–Hf, trace element and REE analyses. 216. Geostandards Newsletter 19, 1–23.