End Paleozoic-Early Mesozoic Western Pangean Reconstruction and Its Implications for the Distribution of Precambrian and Paleozoic Rocks Around Meso-America

Home , Pernambuco fault, Santa Rosa Group

Precambrian Research, 42 (1989) 411-444 411 Elsevier Science Publishers B.V., Amsterdam -- Printed in The Netherlands

END PALEOZOIC-EARLY MESOZOIC WESTERN PANGEAN RECONSTRUCTION AND ITS IMPLICATIONS FOR THE DISTRIBUTION OF PRECAMBRIAN AND PALEOZOIC ROCKS AROUND MESO-AMERICA

DAVID B. ROWLEY

Department of Geophysical Sciences, 5734 S. Ellis Ave., The University of Chicago, Chicago, IL 60637 (U.S.A.)

JAMES L. PINDELL

Department of Earth Sciences, Dartmouth College, Hanover, NH 03755 (U.S.A.)

(Received February 18, 1988; revision accepted July 11, 1988)

Abstract

Rowley, D.B. and PindeU, J.L., 1989. End Paleozoic-Early Mesozoic western Pangean reconstruction and its implications for the distribution of Precambrian and Paleozoic rocks around Meso-America. Precambrian Res., 42:411- 444.

We present a detailed, palinspasticaUy restored reconstruction of the circum-Central Atlantic continents and incorporate information on the distribution, age and correlation of Precambrian and Paleozoic rocks. The Late Paleozoic Appalachian-Ouachita Suture marks a fundamental break which separates Gondwanan from North American basement and pre-Late-Paleozoic assemblages. The westward continuation of the suture across Mexico continues to be problematic, primarily because of the scarcity of pre-Late-Paleozoic rocks. Biogeographic affinities of some Lower Paleozoic assemblages provide some constraints; for example, the North American affinities of the Ordovician and Silurian of Cuidad Victoria versus the Gondwanan affinities of Tremadocian rocks of Oaxaca. The ultramafic rocks within the Mixteca Terrane of southern Mexico may represent the only surface exposure of this suture, the northward strike projection of these exposures to the Coahuila region are compatible with the biogeographical constraints. Some confusion has resulted from geochronologic determinations of 'Grenville' ages from Oaxaca, the Chuacus metamorphics of Yucatan, and the Rio Cana Complex of Cuba; such ages have led to suggestions that these assemblages were derived from North America. We suggest that they are instead part of the Rondonian/Sunsas Orogenic Belt of western Brazil and Ecuador, and that, if this is true, the Rondonian/Sunsas Belt would have represented the areally most extensive basement age province of the Amazon Shield. The Late Paleozoic suture coincidentallyjuxtaposes basement age provinces of similar age, and therefore basement ages appear to be undiagnostic of the paleogeographic affinities of different elements. In addition, we show the geometric correlation of the Senegal Block, west of the Late Precam- brian Pan-African Mauritanide Suture, with the Brunswick magnetic 'terrane' of offshore eastern North America. Other correlations, many of which have been previously recognized, are also highlighted.

Introduction reconstruction of the circum-Atlantic continents have been proposed, most of which differ Since Wegener's (1912) suggestion of a su- only in detail. Reconstructions are based upon: percontinent, Pangea, many variations of the geometric fitting of opposing continental mar-

i ~, ~ /

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Late Precambdan-Pan-African- ...... InferredPan-African Congo-Sao -- Archean Brasilian Orogen-Fomland Foldbeh ~ and Late Precambrian deformed "% Francisco suture m passive margin sections ~ Reworked Archean and Late Precambrian to Cambrian(and "~ Pan-African suture Early Proterozoic ~ possibly younger) intermediate volcanic and plutonic assemblages ~ Early Proterozoic (2.2 - 1.9 Ga) ~ Osceola Granite (post-Pan-African "~ Devonian (?'JCentral Piedmont i Ebumian-Tadilian-Trans-Amazonian pluton) suture Early Proterozoic (Southwestern -] Known, but isolated Precambrian Province, U.S.A.)-Metasedimentary basement outcrops (N, South Late Paleozoic (Alleghenide) and metavolcanic suite iiatruded America and Mexico) and subcrop suture by 1.7 to 1.63 Ga plutonic suite. (Florida) Precambrian and/or Paleozoic Late Early Proterozoic (-1.7-1.5 Ga) i ,.~5 ,,., i metamorphic assemblages Pan-African Foreland-type thrust Rio Negro-Juruena Magmatic Arc r ",." ," i (generally outcrops, but locally Undeformed Early Proterozoic (-1.9- subcrop (W. Venezuela) Undeformed Ordovician to Devonian Pan-African Strike-slip Faults (locally 1.6 Ga)-Intrusives and sedimentary Sediments (Gondwanan Platform) reactivated during the opening of the and volcanic cover ~" SouthAtlantic) ~ Middle ProterozoicGranite-Rhyolite ~ Extemides-Late Paleozoic (1.4 to 1.34 Ga) Appalachian-Ouachita-Marathon ~..jL Late Paleozoic Foreland-type thrust Foldbelt ~ Interides-LatePaleozoic Ouachita- (~'~a~) Post-Cambrian basins (South ~ Uruaqu Orogenic Belt (-1.2 Ga) Marathon Foldbelt America only) with >3 km of ~'-''- sediment Region inferred to be of South ---~ Rondonian & Sunsas Orogenic Belt ~ American Precambrian and/or (-1.4 &-l.0 Ga) includes older Paleozoic derivation, now part of ~..__ Reconsmacted Block Boundaries granulitic components North American continent Region of displaced blocks of Grenville Orogenic Belt (1.11 to 1.07 11 i F I i [ northern S. Am.underlain by variably I" ~/,,x-'[ Ga)-includes older supracrustals and II ~ I : I I remobilized Rondonian/Sunsas (1.4- ~ Present day coastline I " uintrusives (anorthosites)(1.4-1.25Ga) 1.0 Ga) basement

Late Proterozoic to Cambrian Cover ~ Region inferred to be underlain by • Well Location ~ (generally undeformed) I~ h i II Senegal Block (includes Brunswick magnetic 'terrane') ~Late Precambrian-Pan-African- ~ Offshore region of South America Basilian Orogenic Belt (includes large [ i I i [and West Africa infened to be the ----~ Mesozoic-Cenozoic Cover areas of older reworked crust) northern extension of Amazonian basement Fig. 1. End Paleozoic-Early Mesozoic reconstruction of western Pangea with an emphasis on Precambrian and Paleozoic basement geology. Map compiled from sources listed in the Appendix and Choubert and Faure-Muret (1968), Almeida et al. (1973)andUNESCO (1978). gins (Bullard et al., 1965), realignment of mar- the equatorial Atlantic, and (4) the presence of ginal offsets of opposing margins (LePichon Yucatan (Pindell and Dewey, 1982) and Chor- and Fox, 1971; Klitgord and Schouten, 1987), tis (White, 1980) or absence of continental or paleomagnetic constraints (Van der Voo and blocks {Van der Voo and French, 1974) in the French, 1974; Irving, 1977). Significant varia- eventual site of the Gulf of Mexico. Recent work tions in western Pangea reconstructions pri- has begun to address relatively detailed corre- marily include the following: (1) western Af- lations across the basins of the Atlantic. We rica against eastern North America (most present below a detailed reconstruction of the authors) versus northwest South America circum-central and equatorial Atlantic conti- against eastern North America (Morel and Irv- nental masses that (1) incorporates a North ing, 1981), (2) the realignment of geomorphic America-West Africa juxtaposition, (2) re- features of opposing continental margins (e.g., aligns marginal offsets and restores crustal at- the 1000 fathom isobath) versus realignment of tenuation in opposing margins, (3) includes a offset marginal fracture zones (Le Pichon and tight equatorial Atlantic fit, (4) places Yuca- Fox, 1971), (3) a loose (Bullard et al., 1965) or tan, but not Chortis, in the eventual site of the a tight (Pindell and Dewey, 1982) closure of Gulf of Mexico, (5) restores the north margin 414 of South America to its approximate pre-Ter- insula, have been restored (Pindell, 1985). tiary configuration, and (6) places Mexico and Continental crust attentuated during the Chortis along the western margin of Colombia. breakup of this part of Pangea has been re- We use the reconstruction to outline many of stored to its approximate prerift configuration; the previously proposed trans-Atlantic corre- the reconstruction of the margins relies on pre- lations, and to suggest others. The reconstruc- viously published estimates of extension based tion provides a framework that can be tested primarily on restoration of the crust to 'normal' and used to predict the geology of poorly known (~30 kin) continental thickness (Pindell, areas along and across strike from one margin 1985). to another, and as a base upon which to exam- Poles of rotation used to generate the recon- ine other potential pre-breakup correlations. struction displayed in Fig. 1 are presented in Table I. Various aspects of the fit are discussed below. The reconstruction

EquatorialAtlanticandnorthernSouth Figure 1 shows our reconstruction of the cen- Atlantic tral, equatorial and northern south Atlantic, and the Caribbean and Gulf of Mexico region. South America and northwest Africa must be Shorelines are shown, but the limits of pre-Me- reconstructed along the equatorial Atlantic. sozoic continental crust beneath the continen- Both margins have a step-like morphology in tal margins are of greatest importance. Impor- their basements extending from the Demerara tant offshore areas of continental crust include Rise to the eastern horn of Brazil in South the Guinea Plateau (gp)* off West Africa, the America, and from the Guinea Plateau to the Demerara Rise (dr) off Surinam and Guyana, subsurface continuation of the Anambra plat- the Campeche Shelf off Yucatan, and the west- form under the Niger Delta (Whiteman, 1982 ) ern Bahamas (Ladd and Sheridan, 1987). Pri- in Africa; salients must be matched with re- mary areas of Precambrian and Paleozoic rocks TABLEI are shown; other areas composed of either post- Triassic oceanic crust or island arc material are Rotation parameters used to create the Permo-Triassic reconstruction shown in Fig. 1. All rotations are relative to a excluded from this Permo-Triassic reconstruc- fixed North America tion. Important strike-slip fault systems whose offsets are post-Triassic, and have therefore Latitude Longitude Angle changed the original Pangean shapes of the NW Africa - 66.39 165.92 75.23 continental masses, including the Oca (of), S. America -55.00 - 136.58 29.65 Bocono (bf) and Santa Marta (sm) of Colom- S. Africa -61.72 162.96 79.24 NE Africa -63.69 161.82 79.44 bia and Venezuela, the Montagua (eastward S. Florida (TA) -54.55 - 123.70 3.16 extension of the Middle American Trench Mga Block -61.43 - 176.09 1.36 (mat)) and Polochic of Guatemala, the Mo- Yucatan - 28.39 177.95 47.68 jave-Sonora (msm) of north-central Mexico, Ecuador -49.71 - 121.71 32.64 Venezuela - 54.02 - 128.26 30.56 and the Bahamas Fracture Zone (bfz) and Guajira Block -49.34 - 120.64 32.54 Florida Elbow Fault (fef) of the Florida Pen- Yaqui Block - 44.96 88.72 18.55 S. MexicanBlock - 40.39 84.90 28.65 Chortis Block - 36.12 84.51 57.57 *( ) refers to abbreviations on Fig. 1. 415 cesses using transform/fracture zones as flow tion in order to achieve a closed fit of the South lines to obtain a proper fit. Specifically, the De- Atlantic. Details of the deformation history merara Rise must be fitted with the Guinea within Africa and South America associated Plateau, as indicated by opening flow lines de- with the differential opening of the South At- fined by equatorial fracture zones (Haxby, lantic will be discussed elsewhere. The fit of the 1985 ), and by the absence of either continental northern South Atlantic south of the Benue crust or pre-Aptian oceanic crust between them Trough is constrained independently by the (Mascle et al., 1986; Jones, 1987). The most matching of the Pernambuco and Cameroon commonly known reconstruction of this mar- shear zones, and by the Early Cretaceous geol- gin is that of Bullard et al. {1965), who as- ogy of the Benue Trough which suggests left- sumed Africa and South America to be torsion- lateral strike-slip + extensional deformation, ally rigid plates, and which produces a not compression across the Benue Trough reasonable fit in the South Atlantic south of the (Whiteman, 1982; Benkhelil, 1982). Such a fit Benue Trough but results in an ~ 400-km-wide statistically improves the clustering of pre-late gap between the Demerara Rise and the Guinea Early Cretaceous paleomagnetic poles from Plateau, and mismatches flow lines (fracture northwest Africa and south Africa (Lottes and zones) within the equatorial Atlantic (Pindell Rowley, unpublished data, 1988). and Dewey, 1982). Although Bullard et al. (1965) acknowledged that severe overlap of the Central Atlantic 1000 fathom isobaths of the two continents at the Niger Delta was the result of post-breakup A general consensus exists as to the basic ge- sediment accumulation there, they assumed ometry of the closure of the central Atlantic: a that the morphology of the shelf at the mouth comparison of Bullard et al. (1965), LePichon of the Amazon had not changed since breakup, and Fox (1971), and Klitgord and Schouten and thus their reconstruction was deemed sat- (1987) shows only minor differences. The isfactory. Rabinowitz and LaBrecque (1979) model of Irving (1977) for the Late Paleozoic; started with a geometry similar to the Bullard placing northwest South America against east- et al. (1965) fit, and reached a tight equatorial ern North America, is not accepted by most Atlantic geometry by accommodating signifi- authors based on both paleomagnetic and geo- cant shortening within the equatorial region logical arguments (Van der Voo and French, ( ~ 200 km) prior to equatorial Atlantic ocean 1974; Hallam, 1983; Van der Voo and Peinado, opening. The lack of Cretaceous N-S shorten- 1984). The reconstruction must align marginal ing along the equatorial Atlantic suggests that offsets (LePichon and Fox, 1971) and restore their solution is inadequate (Mascle et al., crustal attenuation in the opposing margins 1986). Removing sediment from both the Niger (Pindell, 1985; Sawyer, 1985). The large areas and Amazon shelves, and acknowledging inter- of presumed continental crust beneath the nal deformation in central Africa (Fairhead, in Blake Plateau and western Bahamas are not press) and southern South America (Burke, matched by recesses in the African side of the 1976) during continental breakup, allows a re- Atlantic: this implies that crustal attenuation construction of the equatorial Atlantic that is and/or strike-slip offsets have occurred in the far tighter than the Bullard et al. fit (Rabinow- Florida region in order for this crust to have itz and LaBrecque, 1979; Pindell and Dewey, reached its present configuration. Because es- 1982; Pindell, 1985). The fit shown in Fig. 1 im- timates of crustal attenuation in the Blake Pla- plies that southern Africa has rotated with re- teau and the Bahamas are only approximate, spect to northwest Africa about a pole at the Central Atlantic fit in Fig. 1 is biased to- 9.27°N, 3.74°E, with an angle of -7.25 ° rota- wards a good fit between the margins north- 416 ward of the Blake Plateau. To the north the fit The large thickness of Jurassic and younger is more tightly constrained by the fit of Mo- sediments in this region (Klitgord et al., 1984) rocco to the Grand Banks. supports interpretations that suggest significant continental attenuation. Therefore, it can Strike-slip offsets and accreted terranes only be assumed that the gap between West Af- rica, northern South America, and Yucatan is Further refinement of the reconstruction be- of the proper size to accommodate the pre-Me- yond ocean closure is derived from retracting sozoic crust of south Florida and the western strike-slip offsets that have occurred in several Bahamas. of the continents since the time of continental The southern limit of continental crust of the breakup. In Colombia and Venezuela, Neogene Florida platform appears to lie south of the strike-slip offsets have been documented along presently exposed southern edge of platform the Oca (65 km), the Bocono ( ~ 100 kin), and carbonates along the north coast of Cuba the Santa Marta (110 km) faults (Dewey and (Pardo, 1975). The island of Cuba comprises Pindell, 1986 and references cited therein). part of a Paleocene to Eocene collisional se- These offsets have been retracted to restore ap- quence between a previously oceanic crust- proximately the pre-Neogene shape of north- founded island arc and a sheared-type passive western South America. In addition to the continental margin (Pardo, 1975; Pindell and strike-slip offsets, considerable areas of crust Dewey, 1982). In several regions within this or- have been accreted to the northern and western ogen high grade metamorphic sequences are ex- margins of South America. In the Late Creta- posed, including those of the Rio Cana Com- ceous, the entire Western Cordillera was ac- plex (P) (Renne et al., 1989), Escambray (es) creted to the Central Cordillera and, in the (Trinidad Mts.), and on the Isle of Pines (ip) Cenozoic, the islands offshore from northern (Pardo, 1975), which may reflect the presence Venezuela were emplaced along the mainland of older continental basement in the subsurface (Pindell and Barrett, 1988). These Cretaceous of Cuba. The Rio Cana Complex is widely in- oceanic terranes have been removed from the terpreted as pre-Jurassic basement to the Ci- reconstruction and are not discussed further. fuentes-Placetas Belts (Pardo, 1975; Pszczol- In the Florida area, strike-slip offsets along kowski, 1986; Renne et al., 1989), whereas the the Bahamas Fracture Zone (bfz) (Klitgord et interpretation of the Isle of Pines and Escam- al., 1984) and Florida Elbow Fault (fef) (Pin- bray metamorphics is less clear. The Rio Cana dell, 1985 ), appear to be associated with atten- Complex, which has yielded a 4°Ar-39Ar phlo- uation and migration of the continental crust gopite plateau age of 903.5 + 7.1 Ma (Renne et of southern Florida and the western Bahamas al., 1989), is unconformably overlain by non- to its present position. The reconstruction in- marine and marine clastics, carbonates and corporates ~ 100 km on the Bahamas Fracture cherts of shelf to off-shelf facies of Jurassic and Zone and an additional 50 km on the Florida younger ages (Pardo, 1975; Pszczolkowski and Elbow Fault, as well as a regionally averaged Flores, 1986) that are stratigraphically equiv- factor of ~ 2 for the attenuation of the Florida alent to parautochthonous and autochthonous Straits 'Block' (Pindell, 1985). Estimates of sequences exposed in north Cuba and the Flor- crustal extension in this area are hampered by ida Platform (Pardo, 1975). The Escambray the widespread extrusion (and presumable in- metamorphics, including high pressure assem- trusion) of Triassic/Jurassic basaltic and blages and Jurassic marbles, are exposed in a rhyolitic sequences, which may have added sig- window structurally below Jurassic (?)-Creta- nificant volumes of rock to what appears geo- ceous ophiolitic and arc-related rocks that were physically to be pre-Mesozoic continental crust. transported over the former from the southwest 417 during the latest Paleocene to Eocene (Pardo, of Mexico. Some authors suggest that this hole 1975 ). K-Ar ages from the metamorphics rang- is floored by Paleozoic oceanic crust (Cebull and ing from 80 to 60 Ma (P. Renne, written com- Shurbet, 1980). However, the absence of Upper munication, 1988) have been reported from the Permian and Triassic marine sediments in the Escambray sequence. These presumably reflect Gulf of Mexico area, and the continuity of the obduction-related disturbance. At present no Ouachita-Marathon deformation belt, sug- Precambrian ages have been obtained from this gested to Pindell and Dewey (1982) that the sequence. The Isle of Pines metamorphics are Gulf of Mexico was fully closed in the Permian. dominated by metaclastics and metapelites with This view is also supported by multichannel se- some marbles that are believed to be correlative ismic work throughout the Gulf of Mexico Basin with lower grade sequences in the Organos Belt (Buffier, 1984). Pindell and Dewey (1982) have of western Cuba (Pardo, 1975), and are struc- suggested that the Yucatan Block originated in turally overlain on the northeast by arc-related this gap between the Americas, and that the volcanics that are interpreted to constitute the Gulf of Mexico was formed by the migration of north rim of the Isle of Pines window. K-Ar ages Yucatan to its present position during the Mid- from the Isle of Pines metamorphics yield ages dle and Late Jurassic (Pindell, 1985). Some between 78 and 73 Ma (Meyerhoff et al., 1969 ) models (Dickinson and Coney, 1980; Anderson which are generally assumed to reflect distur- and Schmidt, 1983; Klitgord and Schouten, bance as a consequence of collision and ophiol- 1987) placed the Yucatan block farther west ite obduction. We infer that the rocks of the Rio than this, essentially fixed with respect to Mex- Cana and Escambray metamorphics are par- ico, but in these models Yucatan overlaps with autochthonous slices of basement of the Flor- relatively stable continental crust in the Coa- ida Platform and that the metamorphics of the huila region, south of the Marathon Mountains Isle of Pines may include older basement and/ and northeastern Mexico, and therefore these or the metasediments were deposited on top of models seem unlikely. Figure 1 follows the orig- basement that represents the eastern extension inal suggestion of Pindell and Dewey (1982). of the Yucatan Platform (Fig. 1). Based on Crustal attenuation of the margins of the Gulf these inferences, the southern limit of conti- of Mexico has been extreme. The U.S. Gulf nental crust of the Florida/Bahama and/or Yu- Coast has been extended some 350-400 km, and catan platforms probably extended south of the the northwest Yucatan Shelf by 50-100 km Escambray and Isle of Pines windows, but the (Pindell, 1985; Sawyer, 1985; Dunbar and Saw- precise position of the former continent-ocean yer, 1987). Restoration of the continent-ocean boundary and restoration to the end-Paleozoic boundary by these amounts provides sufficient configuration cannot be determined. The ab- room into which the Yucatan Block, depending sence of Pan-African and/or Alleghanian ov- on how it is geographically defined, is placed. In erprinting in the Rio Cana Complex, but which our view, the southern limit of the Yucatan is observed farther north in Florida (S, slc, ta) Block is defined by the Polochic and Concordia and Yucatan (DSDP sites 537,538A), probably Faults, which bound the rocks of the Upper Pa- reflects the large separation of the Rio Cana leozoic Santa Rosa Group as exposed in the Complex from these orogenic effects (Fig. 1). Chuacus (K) and Cuchumantes (c) ranges of Guatemala (Weyl, 1980; Case and Holcombe, Yucatan and the Gulf of Mexico 1980). In the northeast, the attenuated edge of the Yucatan Block extends beyond the present- The reconstruction of the major continents day locations of DSDP holes 537 and 538A and the palinspastic restoration of attenuated which bottomed in metamorphics that have crust leaves a large hole in the site of the Gulf yielded ~ 500 Ma 4°Ar-39Ar plateau ages inter- 418 preted as the effects of Pan-African orogenesis projecting prong of North America or are de- (Dallmeyer, 1984). Farther east, the basement tached fragments of Gondwana (Stewart, of the Yucatan Block probaby continues on- 1988), similar to Florida (Wilson, 1966). On shore to westernmost Cuba (Pindell, 1985), the reconstruction (Fig. 1 ), Mexico south of the possibly including the Isle of Pines Block as Mojave-Sonora Megashear and west of the shown in Fig. 1. southern continuation of the Tamalipas Arch is draped along the western margin of the cen- Mexico tral Cordillera Block of Colombia, incorporat- ing offsets along the Mojave-Sonora Megash- Mexico south of the Mojave-Sonora Mega- ear and Trans-Mexican Volcanic Belt (after shear (msm) (Silver and Anderson, 1974; An- Pindell and Dewey, 1982), but a gap remains derson and Schmidt, 1983) persists as one of between the inferred extent of continental the most difficult regions to incorporate in basement to the northwest of the Guajira Pen- Pangean reconstructions. This in part reflects insula and to the east of the Late Paleozoic the limited exposure of pre-Mesozoic rocks and granitic rocks that underlie the Sierra de Ta- the extensive covering by Tertiary volcanics and maulipas region of eastern Mexico (Lopez Ra- Cretaceous carbonates (Dengo, 1975; Lopez mos, 1982 ). This gap did not exist at the end of Ramos, 1981, 1982). Failure to account for mo- the Paleozoic, but instead reflects incomplete tion on the Mojave-Sonora Megashear (Silver and/or incorrect palinspastic restoration of and Anderson, 1974) among other strike-slip northern South America and Mexico, and the faults (Walper, 1980 ) results in the substantial use of relatively rigid blocks in regions that have overlap of Mexico and northern South America undergone significant non-rigid deformation. seen in most Pangean reconstructions (Bullard et al., 1965; Smith et al., 1981). Specific evi- Precambrian and Paleozoic geology o[ the dence proving offsets remains conjectural, but reconstruction it appears necessary that most of Mexico be retracted to the northwest to avoid overlap with As outlined above, the reconstruction of Fig. South America until the Late Jurassic when 1 incorporates the primary geometric and geo- central Atlantic opening allowed South Amer- logical aspects known to constrain the proper ica to migrate away from North America. The reconstruction of western Pangea. The Appen- only independent constraints come from off- dix briefly summarizes the pre-Mesozoic geo- sets of occurrences of Paleozoic rocks and Pre- logical and geochronological data from this re- cambrian basement age provinces by 700-800 gion, and also provides a synopsis of important km in the Caborca region of Sonora (Silver and correlations and inferences that have been in- Anderson, 1974; Anderson and Schmidt, 1983 ). corporated in the map. We do not reiterate pre- Paleogeographic reconstruction of the Ouach- viously established correlations that have been ita Belt, including the precise location of the particularly well documented in the South and continuation of the Late Paleozoic suture be- equatorial Atlantic region (Hurley and Rand, tween Gondwana and North America south- 1973; Torquato and Cordani, 1981 ), and in the wards into Mexico beyond the Mojave-Sonora central Atlantic (e.g., Wilson, 1966; Dallmeyer, Megashear, also remains problematic at pres- 1987, 1989; Dallmeyer and Villeneuve, 1987). ent, particularly with respect to whether the Instead we briefly comment upon a few addi- 'Grenville-age' basement and overlying Paleo- tional correlations not previously noted and ex- zoic strata locally exposed in the Sierre Madre amine the potential implications for a contin- Oriental (C, I) and around Oaxaca (F) (Lopez uation of the ~ 1.4-1.0 Ga geochronological Ramos, 1981, 1982) are part of a southward- provinces (Rondonian ( 1.45-1.25 Ga )/Sunsas 419

(1.1-0.9 Ga) provinces) of Cordani and de Brito Craton), Xingu (xn), and Pakaraima (pn)) Neves (1982), Kroonenberg (1982), Priem et which are surrounded, and have been variably al. (1989) and Teixeira et al. (1989) around the remobilized, by early to mid-Proterozoic poly- northern margin of the Amazon Shield. orogenic fold belts (the Birrimian (brfb) Rocks that have been isotopically deter- (~2.27 to ~2.0 Ga) in Guinea and Reguibat mined to be Precambrian in age have a very Rise, Dahomeyan ( ~ 2.1 Ga) superimposed on limited distribution in much of the circum-Gulf the Benin-Nigerian Shield (bns) in Nigeria and of Mexico and Caribbean region (Banks, 1975 ). Benin, Trans-Amazonian (~ 2.2 to ~ 1.8 Ga) For example, there is only one geochronometr- in the Amazon (bmfb, mifb), San Luis {sl), and ically determined Precambrian age that has Sao Francisco shields (belts within sfc), and Rio been reported from Florida (R) (Opdyke et al., Negro-Juruena ( ~ 1.75 to ~ 1.5 Ga) and Ron- 1987), none from subsurface structural highs donian ( ~ 1.4-1.25 Ga) and Sunsas ( ~ 1.1-0.9 along the Gulf of Mexico coastal plain (i.e., Ga) belts) which affect the western and poten- Wiggins Arch (wa), Sabin Arch (sa), or Coa- tially the northern margins of the Amazon Cra- huila (BB to EE), nor from Chortis, a single ton. These early to mid-Proterozoic belts are preliminary age (~ 1.0 Ga) from the Chuacus characterized by substantial reworking of older metamorphics (K) along the southern margin assemblages which are associated with some of Yucatan (Gomberg et al., 1969), several K- relatively isolated occurrences of Archean rocks, Ar (hornblende) and Sm-Nd model separation such as the Imataca Complex (imc), and gran- ages of ~0.94 to ~ 1.8 Ga from exposed Pre- ulite facies Early Proterozoic, including the cambrian and crustal xenoliths of southern (F) Kanuku (ka), Adampada-Falwatra (afc), and and central (C, D, H, I, J) Mexico (Ruiz et al., Ile de Cayenne (ic) complexes of the Amazon- 1987) and one Precambrian date from Cuba (P) ian Craton, and ~2.7 Ga granulites of the (Renne et al., 1989 ). Precambrian rocks are ex- banded gneiss-quartzite complex in the Da- posed north of the Late Paleozoic suture in the homeyan Belt of Benin and Nigeria ( Cahen and Llano Uplift (lo), Witchita Uplift, southern Snelling, 1984). These cratonic areas of west- Blue Ridge (b) and Piedmont (pt), and are ern Gondwana were sutured together during the reasonably well characterized by suites of ages polyphase late Precambrian (~ 700 to ~ 500 of'Grenvillian' ( ~ 1.1-1.0 Ga) whole rock Rb- Ma) Pan-African=Brasilian~West Congo- Sr and U-Pb zircon ages (Easton, 1986; Reed, lian orogenies (Black, 1980; Burke and Dewey, 1987 ), locally superimposed on older ( ~ 1.4 Ga ) 1972). Pan-African deformation and suturing U-Pb and Sm-Nd ages. Farther north a more also involved several elements of uncertain complicated array of age provinces is recog- basement character and paleogeographic affin- nized, which compose the southern margin of ities, such as the Senegal Block (SB), and east- the Canadian Shield (Reed, 1987). ern Yucatan (DSDP sites 537, 538A). The lo- The region south and east of the Late Paleo- cations of Pan-African sutures that separate the zoic Appalachian-Ouachita Suture in the re- shield areas are highlighted in Fig. 1. Wide do- construction is believed to have comprised the mains of reactivated older basement straddle northwestern margin of Gondwana during at the sutures and commonly have strongly dis- least the Late Paleozoic (Pindell, 1985). This cordant trends with older structural belts within region of Gondwana is itself composed of a col- the basement of the cratons. These Pan-Afri- lage of four (West African (gs), Congo (cc), can domains are characterized by 700-500 Ma Sao Francisco (sfc), and Amazonian) cratons. K-Ar biotite and hornblende, and Rb-Sr min- These cratons in turn consist of Archean nuclei eral ages that clearly reflect post-tectonic cool- (Kenema-Man (kmc) and Reguibat (ru), ing, presumably reflecting unroofing of these Ntem (=cc), Jequie (part of Sao Francisco complex orogenic belts. These ages, therefore, 420 do not directly date times of deformation or su- Fig. i the Late Paleozoic suture is assumed to turing. Many of the Pan-African collisions ap- run from the future site of the Atlantic in the pear to have been associated with complex syn- east, essentially parallel with the Brunswick and and post-collisional deformation histories, sim- East Coast magnetic anomalies, across Georgia ilar to that occurring since the Eocene in Asia between the southern Appalachians and the associated with India-Eurasian collision Florida peninsula to the north of the Bruns- (Black, 1980), including complex arrays of wick magnetic anomaly (Tauvers and Muehl- strike-slip faults such as those that affect the berger, 1987), along the northern Gulf Coast Borborema Fold Belt (bofb), northern Congo Basin, south of the exposed Ouachitas (o) and Craton (e.g., csz), Benin-Nigeria (bns) and Llano Uplift (lo), and westward into west Tuareg (ts) shields, and large-scale Tibetan- Texas, then southward into north-central type crustal thickening, which appears to be Mexico, where its location becomes quite un- particularly true for the Pharusian (phfb), Da- certain (Stewart, 1988). Because no other Late homeyian (tba and substantial parts of bns), Paleozoic sutures have been recognized in this Borborema (bofb), Paraguay-Araguaia (pafb), orogenic system (e.g., between Yucatan and and Brasilian (bfb) fold belts. There is also Venezuela), it is possible that the Late Paleo- similarity between the Pan-African and the zoic history of this collision was between the mid-Triassic Indosinian Orogeny of Asia (Sen- two continents only, without intervening con- gor, 1984) as they both involve a complex array tinental blocks and arc systems. On the other of nearly synchronous suture zones separating hand, existing tectonic reconstructions of the previously independent continental blocks Alleghenide collision suggest that a west-dip- characterized by markedly varying intensities ping Carboniferous subduction zone existed of syn- and post-collisional tectonism. along the eastern seaboard of the United States (Hatcher, 1987), and at least a Late Carboni- The Late Paleozoic Alleghenian Orogeny ferous to Early Permian east-dipping subduction zone existed along the greater northern The Late Paleozoic (Permo-Carboniferous) South American margin (including Yucatan, Appalachian-Ouachita-Marathon Orogenic Mexico and Chortis) (Dewey, 1982). Unless Belt (Alleghenides) formed as a result of colli- these two subduction systems were continu- sion between Gondwana and Laurentia, ously connected by a left-lateral transform dur- whereby the intervening oceanic basin (s) were ing the entire ocean-closing history, interven- totally closed (Pindell, 1985). The belt of de- ing plate boundaries, most probably analogous formation and metamorphism includes eastern to the Aleutian Ridge extending oceanward off and southern North America, westernmost Af- present-day Alaska, must have existed within rica, Yucatan, northern South America, and this system during the Carboniferous and would parts of Mexico. The suture between Gond- require at least two Late Paleozoic sutures that wana and Laurasia is not exposed at the surface remain unrecognized in the geologic record. anywhere along its entire length, but its loca- The Late Paleozoic suture as drawn on Fig. 1 tion is inferred from both geophysical signa- is reasonably well defined in the east, particu- tures, such as the Brunswick mggnetic anomaly larly in onland regions of northern Florida and (Tauvers and Meuhlberger, 1987), and bore- southern Georgia, but not offshore to the hole data (Wilson, 1966; Thomas, 1985; Dall- northeast where its signature is concealed un- meyer, 1987, 1989), as well as geological argu- der thick Mesozoic and Cenozoic sediments, and ments based on stratigraphic and structural also by competing magnetic anomaly signa- relationships derived from the exposed por- tures of syn-rift volcanics and intrusives tions of the previously adjacent continents. In (Hutchinson et al., 1982 ). Farther west, the su- 421 ture is drawn to separate Late Paleozoic vol- suture should lie to the east of the Sierra Madre canic and plutonic assemblages recognized from Oriental. This is in sharp contrast to the Tre- drilling, for example in the Wiggins Arch (wa) madocian section (Tinu Formation) in the (Dallmeyer, 1989), Sabine Uplift (sa), Tamau- Oaxaca region (F) which is characterized by lipas Arch (east of C) (Lopez Ramos, 1982), distinctly non-North-American trilobites (in- and drilling and outcrops in the Coahuila re- cluding Parabolina argentina) that are typical gion of north-central Mexico (CC, DD, EE; of South America (Robison and Pantoja-Alor, King, 1975; Handschy et al., 1987) from non- 1968). In the reconstruction (Fig. 1) Oaxaca volcanic, North American Paleozoic offshelf lies adjacent to the northwestern margin of assemblages (e.g., Ouachita and Marathon South America where a very similar lithologic Mountains; King, 1975) overthrust onto the and faunal assemblage is exposed in the E1 Baul continental shelf during the Late Paleozoic High (eh) and Serrania de la Macarena (AA) Laurentia-Gondwana collision (King, 1975; (Etayo-Serna and others, 1983 ). In the E1 Baul Lillie et al., 1983 ). region, Tremadocian carbonates and shales As pointed out above, the position of the su- lithologically similar to the Tinu also contain a ture cannot be defined with confidence still far- Parabolina argentina fauna (Frederickson, ther southwest in Mexico (Stewart, 1988). The 1958). In the Serrania de la Macarena (AA) outcrops near Ciudad Victoria (C), Molango lithologically and faunally similar carbonates (D), Oaxaca (F) and within the metamorphic are exposed in a basement-cored uplift, the assemblages of the Mixteca (mt) and Xolapa gneisses of which remain undated but are sim- (xt) terranes are virtually the only exposures ilar to the Garzon Gneiss (Z) exposed imme- in eastern Mexico, south of the Mojave-Sonora diately to the southwest. The Garzon Group Megashear (msm), from which to constrain the charnockitic and enderbitic granulites, semi- position of the suture (Lopez Ramos, 1982; pelitic gneisses, mafic granulites, amphibolites, Campa and Coney, 1983). The fact that the and calc-silicate marbles have experienced outcrops near Ciudad Victoria (C), Molango granulite facies metamorphism during Sunsas (D), and Oaxaca (F) all have metamorphic orogenesis (Priem et al., 1989; Teixeira et al., basement that yields isotopic ages of ~ 1.0 Ga 1989) that has been dated as 1.18 Ga by Rb-Sr (Ruiz et al., 1987) has been used to correlate whole rock (Alvarez et al., 1983, cited in Etayo- the basement with the Grenville-age province Serna and others, 1983 ) and its post-metamor- to the north. This has in turn been supported phic cooling at between 1.0 and 0.95 Ga based by the correlation of Devonian siliceous rocks on K-Ar hornblende ages (Priem et al., 1989). in the Ciudad Victoria region with the Devon- Unfortunately any Lower Paleozoic rocks that ian novaculites that are characteristic of the might have existed were stripped off the Gar- Marathon and Ouachita exposures (Stewart, zon Gneiss prior to the Carboniferous (Etayo- 1988 ) that would require the Late Paleozoic su- Serna and others, 1983) so that a more direct ture to lie to the east of the Sierre Madre Ori- correlation is not possible. Nonetheless, the ental. As recently pointed out by Stewart geochronological, lithological, and faunal simi- (1988), this correlation of the Devonian is no larities are sufficiently close to suggest that at longer valid, as the siliceous rocks near Ciudad least the South Mexican Block represents the Victoria are now known to be rhyolites, not no- former western margin of Gondwana and that vaculites (see references cited in Stewart, 1988 ). the Gondwana--North America Suture lies to However, the Ordovician and Silurian faunas the north and west of the Precambrian and Pa- that have been reported from the Ciudad Vic- leozoic section exposed at Oaxaca, but south of toria area (Lopez Ramos, 1982) are of North the Ciudad Victoria locality as shown on Fig. 1. American aspect and suggest that indeed the One possibility is that the ultramafics that crop 422 out in the Mixteca Terrane (mt) (Campa and in places, shallow marine fusilinid-bearing car- Coney, 1983) mark the Late Paleozoic suture, bonates of locally Desmoinian to Permian age and would be the one place where this suture is overlie older sections (e.g., sa, c, K, L, M, N, F, exposed. It appears clear that two basement xt, andparts ofCCB, SMB, and Z) (Woods and provinces (Grenville and Sunsas ) of similar age Addington, 1973). The presence of marine units are juxtaposed in eastern Mexico across the implying near sea-level elevations suggests that Late Paleozoic suture, and therefore the posi- large-scale Tibetan-type crustal thickening did tion of the suture cannot be independently cor- not accompany the collision in this region. roborated by basement age data. Thus the affinities of localities such as Molongo (D), or Rondonian/Sunsas age province and northern basement xenoliths (H, I, J) are not able to be South America determined at this time. Paleozoic igneous, metamorphic and defor- The Rondonian/Sunsas orogenic zone lies mational activity affect a wide region on both along the western margin of the exposed area sides of the Late Paleozoic suture. In North of the Precambrian Amazonian Shield and is America, the Late Paleozoic collisional effects characterized by mainly amphibolite facies are clearly seen in the Carolina Slate Belt (csb), migmatite and granitic-and granodioritic Piedmont (pt), Talladega Slate Belt (tsb), gneisses that yield metamorphic and intrusive Valley and Ridge (vr), Ouachita (o), and Mar- ages between 1.45 and 1.25 Ga (Rondonian) and athon (m) regions, but also extend well into the deformed post-Rondonian metasediments in- North American continent, along the Ken- truded by syn- to post-tectonic granites that tucky River, Rough Creek, and Cottage Grove yield 1.1-0.9 Ga ages attributed to the Sunsas fault systems (Dewey, 1982) to the north of the Orogenic Cycle (Kroonenberg, 1982; Lither- map, and along the Arbuckle-Anadarko-Wich- land, 1986; Priem et al., 1989; Telxeira et al., ita (ab region) and Ancestral Rocky Moun- 1989). Both the Sunsas and Rondonian belts tains farther west (Kluth and Coney, 1981 ). include older metamorphics and/or show deri- South and east of the suture, Paleozoic tectono- vation from older (> 1.5 Ga) basement (Cor- thermal effects extend from local reactivation dani and de Brito Neves, 1982; Priem et al., in the northern Mauritanide Fold Belt (mfb) 1989; Teixiera et al., 1989). Basement gneiss (LeCorche et al., 1983 ), age resetting and pos- assemblages that yield similar, and generally sible mylonitization in the eastern Bassarides Sunsas, ages are exposed in the Garzon Block (bs), where Dallmeyer and Villeneuve (1987) (Z), Central Cordillera Block (Y), Santa Marta and Dallmeyer (1989) report 278-271 Ma ages, Block (V, W, X), Guajira Block (U), Oaxaca to the Wiggins (wa) and Sabine (sa) arches, (F), Yaqui Block (D, I), Yucatan Block (K), Coahuila Platform (CC, DD, EE), the base- the Rio Cana Complex (P) that we infer to be ment of the Tamaulipas Arch {east of C), the representative of the South Florida Block, and basement of Yucatan (c, K, L, M, N, O, and are possibly represented by rare 1.3 Ga ages in DSDP sites 537 and 538A), the region north the Kasila and Marampa complexes of the Ro- and west of the Apure Thrust (at) in Venezuela kelide Belt of Sierra Leone, where they are and Colombia (CCB, SMB, GB), the plutonic clearly superimposed on older Archean base- and metamorphic assemblages of the Oaxaca ment (see Cahen and Snelling, 1984). This (F), Mixteca (mt) and Xolapa (xt) terranes of Sunsas-age basement is overlain by distinctive southern Mexico, and metamorphics of the Early Paleozoic sediments of clearly Gond- northern Chortis Block (Horne et al., 1976). wanan affinities, including the Ordovician in Over much of the central and western part of the Bove Basin (bb), Suwanee Basin (sb), this collisional zone non-marine red beds and, Oaxaca (F), and northern South America (eh, 423

AA) which appears to provide additional sup- when compared on a Bullard et al. (1965) South port for a coherence of the basement of this Atlantic reconstruction. We do not accept these province during at least the Ealy Paleozoic. If correlations. Using our revised equatorial At- this age province is indeed coherent, and were lantic reconstruction the Onstott et al. (1984) to extend to at least the nearest Pan-African or paleomagnetic poles are no longer superim- younger suture then this would in turn imply posed by a simple E-W rotation of the Amazon- that the Rondonian/Sunsas Province would ian Shield with respect to West Africa, but in- represent the areally most significant base- stead require NE-SW motion (South America ment age province of the Amazon Shield. Trias- with respect to West Africa) strongly oblique sic and Jurassic crustal attenuation appears to to the equatorial margin, not parallel to it. In have preferentially affected this province, and addition, and as acknowledged by Cohen and the region immediately adjacent to the Late Gibbs {1989), the orientations of the major Paleozoic suture, which has resulted in the Early Proterozoic (Trans-Amazonian on South substantial dismemberment of this province. America, and Eburnean on West Africa) structures on the Amazonian and Guinea shields are Basement control on the breakup of perpendicular to one another, not parallel when Pangea reconstructed {Fig. 1 ); an unexpected result if they were part of the same Early Proterozoic Domains of basement weakness, and in par- continental mass. Finally, such a suggestion ticular old suture zones, have long been as- downgrades the Pan-African Rokelide-Sierra sumed to control the geometry and location of Leone-- Brasilian Sao Luis-Paraguay-Ara- subsequent ocean opening (Burke and Dewey, guaia Fold Belt, which has been interpreted as 1973). The extensional domains of the east a suture by some {Burke and Dewey, 1972), into coast, north of the Blake Plateau, northern an intracratonic fold belt. Florida and the Gulf Coast support such sug- Alternatively, it is interesting to note and gestions, whereas the strongly discordant na- perhaps not unreasonable to suggest that the ture of the equatorial Atlantic margin with absence of appropriately oriented domains of structural trends of the Dahomeyian and pre-existing structural weakness along equato- northern Borborema Fold Belt do not follow this rial Atlantic and east coast Florida peninsula general pattern (Cohen and Gibbs, 1989). margins are what caused the differential open- Cohen and Gibbs (1989) have suggested that ing histories associated with these regions. As in fact a pre-existing dextral strike-slip system pointed out above, simultaneous fits of the now buried by post-late Early Cretaceous South and equatorial Atlantic can only be breakup sediments provides a link between the achieved if internal deformation is taken into equatorial and South Atlantic. They supported account within Africa and South America. The the existence of this structure by noting strong earlier, Berriasian to early Albian, South At- lithologic and geochronologic similarities be- lantic opening followed pre-existing, primarily tween the Archean and Early Proterozoic of the Pan-African, zones of weakness, and at its Amazon and Guinea shields, which, when northern end included reactivation of the Per- placed on a reconstruction like that of Bullard nambuco, Cameroon, Dahomeyan and Pharu- et al. (1965), such as that of Lawver and Scotese sian shear zones prior to the development, in (1987), are offset by ~ 1000 km. They in turn the early to mid-Albian, of the discordant con- noted that Onstott et al. (1984) had previously tinent-ocean boundary-related structures that pointed out that Early Proterozoic paleomag- finally allowed the South and central Atlantic netic poles from the respective shields can be plate boundaries to become linked. The linking superimposed with a similar amount of motion, of these systems thereby deactivated the central 424

African domains of deformation. A similar ar- Amazon shields, the amalgam which comprises gument may also be valid for the differential the western portion of Paleozoic Gondwana. opening history north and south of the Blake The pre-Mesozoic continuation of the Amazon Plateau, including the additional differential Shield is inferred to extend northward to the extension between the Blake Plateau and South Bassaride Suture of West Africa and then west- Florida Block, where structural trends are un- ward to include the Florida Peninsula up to the known but might be reasonably expected to Brunswick magnetic terrane, and regions far- parallel the Bassaride Suture to the north and ther west including Yucatan, the Gulf Coast Barama-Mazaruni Fold Belt to the south, both basement highs, the Coahuila Platform, the of which are perpendicular to N-S orientation south Mexican Block and Chortis. Where dated of the western margin of the Guinea Plateau most of these regions are underlain by ~ 1.1- and Demerara Rise. Farther west in Yucatan 1.0 Ga basement correlative with the Rondon- and Mexico it is less clear what the orientation ian/Sunsas of western Brazil, which is overlain of domains of weakness were during Mesozoic by Lower Paleozoic sediments with faunas of extension, but the complex history of differen- Gondwanan affinity (Suwanee Basin and Oax- tial opening between the Gulf of Mexico, and aca) that are correlative with Gondwanan sed- northern South America and southern Mexico imentary sequences of the Amazon, Parnaiba, might suggest that the final continent-ocean and Bov~ basins, as well as those preserved in boundary orientations developed discordantly the E1Baul High and Sierrania de la Macarena. across early zones of weakness, thereby giving Pre-Late Jurassic extensional disruption ap- rise to large-scale strike-slip displacements pears to have been concentrated within this belt along the Mojave-Sonora Megashear and of Rondonian-age basement that rims the Trans-Mexican Volcanic Belt. northern margin of the Amazon Shield, and the region affected by Late Paleozoic basement Conclusions reactivation associated with the Gondwana- Laurasia collision. The Mesozoic and Cenozoic opening of the The Late Pan-African Mauritanide Suture central, equatorial and South Atlantic, Gulf of separates the Guinea Shield from the almost Mexico, and proto-Caribbean has disrupted entirely subsurface Senegal Block, which is in once contiguous segments of western Pangea. turn bounded by the Late Precambrian Bassar- Reconstruction of this region to its end Paleo- ide Suture on the south and Late Paleozoic Ap- zoic configuration requires not only the fitting palachian suture on the west. Most other cor- of continent-ocean boundaries and palinspas- relations, particularly those across the South tic restoration of syn-rifting crustal attenua- and equatorial Atlantic have been established tion, but also the restoration of motion along previously and are simply reconfirmed by this numerous major strike-slip faults. Figure 1 pre- more detailed reconstruction. Some of these, sents such a reconstruction upon which the such as the correlation of the Kasila and Mar- distribution of Precambrian and Paleozoic as- ampa with the Barama-Mazaruni Fold Belt and semblages and sutures have been mapped. The Ile de Cayenne Complex are accenuated with Late Paleozoic Appalachian-Ouachita Suture the palinspastic restoration of Early Creta- separates Gondwana from North American as- ceous deformation within Africa resulting from semblages but is nowhere exposed at the sur- differential opening of the South and equato- face, with the possible exception of within the rial Atlantic ( Pindell and Dewey, 1982; Pindell, Mixteca Terrane of southern Mexico. Late Pre- 1985). cambrian Pan-African sutures bound the large The history of opening of the South, equa- Guinea, Taureg, Congo, Sao Francisco, and torial and central Atlantic appears to have been 425 significantly influenced by the distribution and C orientation of pre-existing domains of weakness. Early extensional deformation in the Novillo Gneiss (pyroxene granulite): 0.9 Ga South Atlantic and southern central Atlantic (Sm-Nd garnet, Ruiz et al., 1987) unconform- paralleled pre-existing domains of weakness ably overlain by a thin Cambrian (?), Ordovi- but, in regions such as the equatorial Atlantic, cian to Pennsylvanian succession and a thicker Blake Plateau and Florida Peninsula where ( > 1 km) Lower Permian flysch sequence (Lo- structural trends are oriented perpendicular to pez Ramos, 1981). The Ordovician and Silu- final margin orientation, appears to have ini- rian faunas appear to have affinities with North tially inhibited plate boundary propagation, and America. to have resulted in significant non-rigid internal deformation within Africa and Florida, and D possibly within Mexico. Huiznopala Gneiss (pyroxene granulite): 0.9 Ga Acknowledgments (Sm-Nd garnet, Ruiz et al., 1987 ) unconformably overlain by thin Mississippian lutites, un- We wish to thank T. Onstott for extreme pa- conformably overlain by Lower Permian flysch tience while completing this manuscript and T. (Lopez Ramos, 1981). Onstott, P. Renne and R. Hargraves for helpful and thorough reviews. We thank K. Burke and E D. Dallmeyer for discussions of Precambrian geology of the circum-Atlantic region. DBR Los Filtros Gneiss: 1.0 Ga (K-Ar hornblende, would like to thank A. Lottes, A.M. Ziegler, and Mauger et al., 1983) imbricated with Permian T. Gierlowski for assistance during the final flysch, and La Olivina xenolith locality with preparation of the manuscript. The support of 1.52-1.39 Ga Sm-Nd model age (Ruiz et al., AMOCO, ARCO, BHP-Utah International, 1987). BP, Chevron, Conoco, DEC, Elf Aquitaine, EXXON, Mobil, Shell, Sohio, Sun, Texaco, and F Unocal is gratefully appreciated. Oaxacan Complex: includes charnockites and Appendix meta-anorthosites with 0.96 and 0.94 Ga Sm- Nd model ages (Ruiz et al., 1987), unconform- Abbreviations, ages and significant ably overlain by Cambrian(?), and Early Or- Precambrian and Paleozoic assemblages from dovician (Tremadocian), and in turn un- the circum-Gulf of Mexico, Caribbean and conformably overlain by Mississippian, southern central Atlantic region Pennsylvanian, and Permian marine and non- marine sediments. Tremadocian faunas are A non-North American, with closest affinities to faunas from Argentina (Robison and Pantoja- Chihuahua: 1.7-1.6 Ga basement gneisses (An- Alor, 1968) and Venezuela (Frederickson, derson and Silver, 1983). 1958).

B G

Caborca Gneisses (off of map): 1.8-1.7 Ga Potrillo xenolith locality: 1.30 Ga Sm-Nd model (Anderson and Silver, 1983 ). age (Ruiz et al., 1987). 426

H P

Santo Domingo xenoliths: 3 samples with 0.98- Cuba, Rio Cana Complex, metasediments: 0.80 Ga Sm-Nd model age, and 3 samples with ~ 903.5-7.1 Ma 4°Ar-39Ar plateau age on phlo- 1.72-1.56 Ga Sm-Nd model age (Ruiz et al., gopite, intruded by Sierra Morena Granite 1987). (172 + 4 Ma) containing inherited zircons with an approximate age of 900 Ma, and with the K- Ar system in phlogopite showing a disturbance at 59.5_+9.4 Ma (Renne et al., 1989). Ventura Maars xenoliths: 1.05-0.67 Ga Sm-Nd model age (Ruiz et al., 1987). Q J Florida, Suwanee Basin, muscovite (detrital): E1 Toro xenoliths: 1.52 Ga Sm-Nd model age 504 + 2.1 Ma 4°Ar99Ar plateau age (Dallmeyer, (Ruiz et al., 1987) (single sample). 1987).

K R Chuacus Group (gneiss): discordant 1.07_+ 25 Ga U-Pb zircon disturbed at 345_+25 Ma Florida, Suwanee Basin, zircons (detrital): dis- (Gomberg et al., 1969). cordant 1800-1650 Ma 2°Tpb-2°6pb (Opdyke et al., 1987 ). L S Yucatan no. 1, meta-andesite: ~ 330 Ma U-Pb (Bass and Zartman, 1969), 290 Ma Rb-Sr whole Florida, Osceola Granite: ~ 535 _+ 2 to ~ 527 + 2 rock and rhyolite ~ 410 Ma Rb-Sr (Lopez Ra- Ma biotite 4°Ar-39Ar plateau ages believed to mos, 1975 ). It is not clear if all of these ages are date closely emplacement of the pluton, and from the same sample and therefore reflect var- temporally and geochemically similar to the ious alteration problems. Coyah Granite (T) (Dallmeyer et al., 1987). M T Yucatan no. 4, metaquartzite: (undated) (Lo- pez Ramos, 1975). Guinea, Coyah Granite: 533+7 Ma biotite, muscovite, and whole-rock Rb-Sr isochron N (Dallmeyer et al., 1987). Post-tectonically intruded into the Rokelide Belt (Dallmeyer et al., Basil Jones no. 1, schist: (undated) (Lopez Ra- 1987). mos, 1975).

O U

Tower Hill no. 1, granite: (undated) (Lopez Guajira Peninsula Block, Jojoncito Granite: Ramos, 1975). 1250 Ma U-Pb (Irving, 1971). 427

V AA

Santa Marta Block, Los Mangos Gneiss: Serrania de la Macarena 'Terrane': basement- 940 + 34 Ma Rb-Sr whole rock (Tschanz et al., cored uplift, overlain by undated Cambrian (?) 1969, cited in Etayo-Serna and others, 1983). carbonates intruded by undated dolerite dikes, in turn overlain by marine Lower Ordovician carbonates and shales (Tremadocian), quartz- W itic arenites (Arenigian) and carbonaceous shales ( Llanvirnian ) (Etayo - Serna and others, Santa Marta Block, Dibulla Gneiss: 1400 + Ma 1983). Rb-Sr whole rock (McDonald and Hurley, 1969). BB

X Las Delicias-Acatita (Coahuila 'Terrane'): Pennsylvanian(?) to Permian interbedded shales, graywackes, basic and intermediate vol- Santa Marta Block, Bucaramanga Gneiss: canics and volcaniclastics, and reef-type car- 945 + 40 Ma K-Ar hornblende, 680+ 140 Ma bonates, intruded by granodiorite that yields a Rb-Sr biotite (Goldsmith et al., 1971, cited in 210_+ 4 Ma K-Ar biotite age (corrected from Etayo-Serna and others, 1983 ). Denison et al., 1969).

Y CC

Central Cordillera Block, Tierradentro Gneiss: Potrero de la Mula (Coahuila 'Terrane'): I-type 1360 + 270 Ma K-At hornblende (Barrero and granite which yielded a K-Ar age of 211 ___8 Ma Vesga, 1976, cited in Etayo-Serna and others, and an Rb-Sr age of 213 + 14 Ma (Jones et al., 1983). 1984).

DD Z Collection of four wells: Minas Viejas, no. 101 Garzon Massif: older augen gneiss basement Chapa, no. 1 Ceralvo, and Carbajal that bot- including the Mancagua and Guapoton gneisses tomed in undated, but assumed Late Paleozoic, from which a 1596 + 300 Ma Rb-Sr whole-rock low-grade metamorphic basement (see Hand- isochron has been obtained, and overlain by a schy et al., 1987), and Valle San Marcos Gran- supracrustal sequence metamorphosed to granodiorite (point farthest west) which yielded a ulite facies at ~ 1.18 + Ga based on an Rb-Sr 242 + 2 Ma Rb-Sr age (Jones et al., 1982). whole-rock isochron (Alvarez et al., 1983, cited in Etayo-Serna and others, 1983; Kroonenberg, EE 1982; Priem et al., 1989). K-At ages from horn- blendes yield ages ranging from ~ 1.0-0.95 Ga, Collection of three wells, including the no. 2A reflecting post-metamorphic cooling (Priem et Peyotes, no. 1 La Perla, and no. 1 Garza wells al., 1989). This basement is overlain uncon- (King, 1975, Handschy et al., 1987). No. 2A formably by Carboniferous argillaceous aren- Peyotes bottomed in undated, but assumed Late ites and limestones (Etayo-Serna and others, Paleozoic, schist, no. 1 Garza in undated slate 1983). and quartzite, and the La Perla no. 1 bottomed 428 in granitic gneiss that yielded a 371 + 60 Ma Rb- by the Romeral Suture (rms), and the Santa Sr whole rock age (corrected from Denison et Marta (sm) and Bocon6 (bf) transpressive al., 1969) assuming an initial ratio of STSr/ strike-slip faults on the east and southeast, S6Sr = 0.706. respectively.

FF GB

Well from Case and Holcombe (1980) that is Guajira Block: Precambrian and Paleozoic reported to have bottomed in Precambrian basement from the Guajira (U) and Paraguana basement at 2723 m. Peninsula (pp), bounded on the north by Cre- taceous to Tertiary oceanic arcs (see Pindell and GG Barrett, 1988) (not shown ) and to the south by the Oca Fault (of). CN well bottomed in quartz monzonite with a 1.9 Ga isochron at ~ 1060 m (location no. 24, SB Feo-Codecido et al., 1984). Sergipe Block: Archean and Early Proterozoic (Wernick, 1981; Cordani and de Brito Neves, HH 1982) basement block (probably the western extension of the Ntem-Du Chailu Massif of the San Quentin Anorthosites, undated, that are Congo Craton (cc) ) reactivated during the Pan- lithologically correlated with anorthosites of the African. Late Jurassic and Early Cretaceous Sierre Nevada de Santa Marta in Colombia by left-lateral motion of ~25-30 km along the Priem et al. (1989). Pernambuco Fault (pf) accompanying extension of the Reconcavo-Tucano Basin (Mabe- DSDP soone et al., 1981; Castro, 1987 ) associated with South Atlantic opening results in overlap with Site 537: Catoche Knoll, eastern edge of the Yu- Africa if it is not reconstructed as shown in Fig. catan Block, phyllite: discordant 449 +_ 11 Ma 1. and 456 + 10 Ma, with one sample showing a 500 + 8 Ma plateau, 4°Ar-39Ar whole-rock ages SMB (Dallmeyer, 1984; Schlager and others, 1984). Santa Marta Block: Precambrian and Paleo- DSDP zoic assemblages exposed in the region bounded by the Oca Fault (of) to the north, the Santa Site 538A: Catoche Knoll, eastern edge of the Marta Fault (sm) to the west, and Bocon6 (bf) Yucatan Block, amphibolitic gneiss: 501 + 9 Ma, Fault on the southwest. 496 _+ 8 Ma, 4°Ar/39Ar hornblende plateau ages, 348 + 8 Ma biotite age (Dallmeyer, 1984; Schla- SNB ger and others, 1984). Senegal Block: block with an uncertain, but CCB necessarily Precambrian, basement bounded on the east by the Pan-African Mauritanide Su- Central Cordillera Block: Precambrian base- ture (ms), on the south by the Pan-African ment overlain by Paleozoic rocks belonging to Bassaride Suture (bs), and on the east by the the Cajamarca and Payande terranes of Etayo- Late Paleozoic Appalaehian-Ouachita Suture. Serna and others (1983), bounded on the west Includes the Brunswick magnetic 'terrane' of 429

Williams and Hatcher (1982). Calc-alkaline and ultramafic pods, interpreted to be early Pa- arc-type volcanics and comagmatic plutons are leozoic ophiolites (Hatcher, 1987). The last exposed along the eastern margin of the block phase of overthrusting occurred synchronously (LeCorche et al., 1983) that have yielded Rb- with deformation in the adjacent Valley and Sr and 40Ar-3~Ar ages of 685 to ~ 635 Ma (Dall- Ridge Province (Cook et al., 1979). meyer and Villeneuve, 1987; Dallmeyer, 1989). bb ab Bovd Basin: undeformed Late Ordovician to Anadarko Basin: Late Precambrian-Early Devonian platformal succession disconforma- Cambrian failed arm (Burke and Dewey, 1973), bly overlying the Youkounkoun Group in the opened and then inverted during the Pennsyl- north and unconformably overlying the Roke- vanian (Kluth and Coney, 1981). lide-southern Mauritanide Suture and associated fold belt along its eastern margin (Cahen ale and Snelling, 1984; Wright et al., 1985; Dall- meyer and Villeneuve, 1987). Base of the Adampada-Falwatra Complex (Hurley and succession characterized by Ashgillian glacial Rand, 1973 ): part of the Central Guyana gran- tillites derived from the Saharan glaciation. ulitic belt of Teixeira et al. (1989) of Trans- Bov~ Basin sequence is equivalent to sections Amazonian (~2.2-2.0 Ga Rb-Sr whole-rock preserved within the Taoudeni Basin to the age, Priem et al., 1978) granulite facies com- north and Suwanee Basin in northern Florida ponents of the Maroni-Itacaiunas Province and (Wilson, 1966). invaded by Trans-Amazonian granites at ~ 1.9 Ga (Teixeira et al., 1989). bf at Bocono Fault: Late Miocene to Recent transpressional right-lateral strike-slip fault Apure Thrust: subsurface-defined Late Paleo- with ~ 100 km of offset (Dewey and Pindell, zoic southeast-vergent thrust that delimits the 1986) which has been accommodated within the region within Venezuela affected by Paleozoic reconstruction. overprinting, particularly in terms of isotopic ages (Feo-Codecido et al., 1984). We infer that bfb Espino 'graben' of Feo-Codecido et al. (1984) is a foredeep basin developed in front of the Brasilian Fold Belt: type Late Precambrian Apure Thrust, and that the Altamira and Trico Brasilian fold belt of South America. Outlines normal faults that define the southeastern the northern margin of the Sao Francisco Cra- margin of the Espino 'Graben' (Feo-Codecido ton (sfc), and truncates older orogenic trends et al., 1984) are flexurally controlled and asso- within the Sao Francisco Craton (Almeida et ciated with underthrusting of the Amazon al., 1981). Interpreted here as part of a region Shield below this Paleozoic orogen. of remobilized Sao Francisco cratonal basement (extending eastward to the Guaxupd Massif (gm) of the Tocantins belt) associated with the Late Precambrian collision of the Sao Blue Ridge: west-vergent Grenville-basement- Francisco Craton and Amazon Shield (A1- cored overthrust, including Late Precambrian meida et al., 1973, 1981; Cordani and de Brito metasediments and metavolcanics, and mafic Neves, 1982 ). 430 b/z both

Bahamas Fracture Zone: westward extension of Borborema Fold Belt: polyphase deformed belt, a central Atlantic fracture zone that defines the last deformed in the Brasilian ( = Pan-African ) northern margin of the South Florida Jurassic but including older, variably remobilized gneis- Volcanic Province (Klitgord et al., 1984). Ap- sic-migmatitic-granitic basement blocks, lo- proximately 100 km of left-lateral strike-slip cally of Archaean (~2.7 Ga) and more com- motion is assumed along this fault and has been monly Trans-Amazonian (2.1-1.9 Ga) age. accounted for in the reconstruction. Brasilian (~ 650-550 Ma -- younger ages are K-Ar mica cooling ages) deformation is char- bmfb acterized by folding and large-scale right-lateral shear deformation along E-W and NE-SW Barama-Mazaruni Fold Belt (Hurley and striking shear zones, including the Pernam- Rand, 1973): northern extension of the Ma- buco, Patos, and Jaguaribe faults (Almeida et roni-Itacaiunas Province of Cordani and de al., 1981; Cordani and de Brito Neves, 1982). Brito Neves ( 1982 ) and Teixiera et al. (1989). Formerly part of the much larger Borborema- Includes Trans-Amazonian granite-green- Dahomeyan-northern Cameroon Brasilian- stone assemblages separating the Archean Im- Pan-African Orogen. ataca (imc) and Pakaraima (pn) nuclei of Cor- dani and de Brito Neves (1982), and intruded brfo by undeformed post Trans-Amazonian ( 1.9-1.8 Ga) granites along its southern margin (Hur- Birrimian Fold Belt: domain of predominantly ley and Rand, 1973; Cordani and de Brito Neves, Early Proterozoic metasedimentary, metavol- 1982 ). canic, and granitic rocks affected by Eburnean (~2.27 Ga (early phase), ~2.13 (middle bns phase ), and ~ 2.04 (late phase ) ) deformations, that produced the predominantly N-S to NE- Benin-Nigeria Shield: region characterized by SW strike of the regional foliation (Cahen and complexly deformed high-amphibolite facies Snelling, 1984). gneisses, migmatites and remnant charnockites that locally yield Archean to Early Proter- bs ozoic ages (2.7-2.1 Ga), intruded by Older Granites (677-523 Ma) and characterized by Bassaride Suture: Late Pan-African E-W significant resetting of K-Ar and Rb-Sr sys- trending suture separating the Senegal Block tems during the Late Precambrian Pan-African (SNB) from the Kasila Group Metamorphics Orogeny (Grant, 1973; Black, 1980; Cahen and (k) (Dallmeyer et al., 1987). Southern exten- Snelling, 1984). Bounded on the west by meta- sion of the Mauritanide Suture. Westward(?) morphics of the Benin Plain that include basic- continuation is the Brunswick anomaly sepa- ultrabasic assemblages, which have been inter- rating northern Florida from an unnamed off- preted by some as ophiolitic rocks (Affaton et shore assemblage correlated with the Bruns- al., 1980) that mark the Pan-African Suture wick magnetic 'terrane' of Williams and adjacent to the Togo-Buem-Atacora Fold Belt, Hatcher (1982) and the Charleston magnetic between the Guinea Shield and Benin-Nige- 'terrane' of Tauvers and Muehlberger (1987) rian Shield (Burke and Dewey, 1972; Black, that probably corresponds to the Senegal Block 1980). of west Africa. 431 bt tic faunal province (Secor et al., 1983). The Carolina Slate Belt collided with North Amer- Benue Trough: Early Cretaceous extensional ica during the mid-Paleozoic (probably Devon- and left-lateral pull-apart basin (Benkhelil, ian Acadian Orogenic event), prior to the A1- 1982; Fairhead, in press) that accommodated leghenian collision of Laurasia and Gondwana in part the differential opening of the South and (see recent review by Hatcher, 1987). equatorial Atlantic (Pindell and Dewey, 1982; Pindell, 1985). CSZ

Cameroon Shear Zone: Pan-African right-lat- Sierre de los Cuchumantes: exposure of un- eral shear zones associated with regions of Pan- dated Paleozoic metamorphics overlain by Late African and older remobilization of Congo Cra- Paleozoic Santa Rosa Group red beds (Weyl, ton basement. Basement within this region 1980). typically yields 580-530 Ma mineral ages reflecting Pan-African reactivation (Cahen and CC Snelling, 1984). Shear zones part of syn-collisional strain accommodation similar to that of Congo Craton: Archean charnockites, migma- Asia today. Cameroon shear zones and Per- tites and gneisses of the Ntem Complex (2.96 nambuco and Patos faults of the Borborema Ga), unconformably overlain by various Early Fold Belt on South America are formerly con- and mid-Proterozoic metasedimentary and me- tinuous elements (Torquato and Cordani, tavolcanic sequences, including the uraniferous 1981). Francevillian host of the Oklo natural nuclear reaction site (~ 1.98-1.93 Ga). Late Precam- brian sediments of the West Congolian Basin ct unconformably overlie Tadilian (~Ebur- nian ~ Trans-Amazonian -- 2.1 Ga) and Ar- chean basement along the western margin of the Cantagallo (NW) and Guarico (SE) Thrusts: Congo Craton. Pan-African deformation of the subsurface-defined Carboniferous (?) thrusts West Congo Orogen and remobilization of Ar- that are part of a Late Paleozoic orogenic belt chean and Early Proterozoic basement char- in western Venezuela (Feo-Codecico et al., acterize the western margin of the Congo Cra- 1984). ton, and reflect a collision between the Congo Craton and Sao Francisco Craton of South dr America (Cahen and Snelling, 1984). csb Demerara Rise: bathymetric high off the northern margin of South America. Pre-drift contin- Carolina Slate Belt: a Late Precambrian to uation of the Guinea Plateau of West Africa. Cambrian volcanic and volcaniclastic assem- Note that equatorial Atlantic fracture zones blage that has yielded Rb-Sr and U-Pb {zir- demonstrate that the Guinea Plateau and De- con) ages of 650 + 30 Ma to 552 + 7 Ma, and is merara Rise were contiguous in the pre-drift overlain by shales characterized by a non- configuration, whereas the Bullard et al. (1965) North-American Middle Cambrian Paradox- South America-Africa reconstruction places ides trilobite fauna characteristic of the Atlan- them ~ 200 km apart. 432 eh 1.11-1.07 Ga) orogeny that involved a supracrustal assemblage, charnockites and anor- El Baul High: small exposure within the Sub- thosites of ~ 1.4-1.25 Ga age range (Moore et Andean foredeep basin of Paleozoic low-grade al., 1986; and recent review by Reed, 1987). metasedimentary rocks (The E1 Barbasco Group, which includes the Tremadocian Mir- g/b eles Formation which is lithologically similar to the Tinu Formation of Oaxaca and contains the Gourma Fold Belt: northern continuation of the same non-North-American trilobite (Parabol- Togo-Beum-Atacora Fold Belt along the east- ina argentina) (see Frederickson, 1958) as the ern margin of the West African Craton. Com- Tinu (see Robison and Pantoja-Alor, 1968)). prises a thick succession of Late Precambrian This sequence is intruded by a Permian alka- (< ~800 Ma) non-marine to marine passive line granite that has yielded dates of 287 +_ 10 margin sequences believed to have originated in Ma (Rb-Sr) and 270_+10 Ma (K-Ar) (Feo- a failed arm of the rift system that created the Codecido et al., 1984). eastern margin of the West African Craton at ~800 Ma (Black, 1980). e8 gm Escambray: sequence of enigmatic metamorphic rocks exposed on the south coast of Cuba Guaxupe (or Goias) Massif: basement of the in the Trinidad Mountains (Pardo, 1975). As- Tocantins Province, including Archean sumed to include basement and unconformable ( 3.9 ( ? ) - > 2.6 Ga ) and Early Proterozoic gran- cover including marbles, from which Oxfor- ulitic gneiss, granitic, and migmatitic base- dian(?) ammonites have been recovered, that ment, adjacent to the west of, and variably re- have been subsequently interleaved and remo- mobilized by the Late Proterozoic ( ~ 1.0 Ga) bilized during the Paleocene to Eocene obduc- Uruaqu Fold Belt, and bounded both to the east tion and collision with the Greater Antillean Arc (Brasilia Fold Belt) and west (Paraguay-Ara- (Pindell and Dewey, 1982; Pindell and Barrett, guaia Fold Belt ) by Brasilian age fold belts (A1- 1988). Assumed to define approximately the meida et al., 1981; Cordani and de Brito Neves, southern margin of the South Florida Block. 1982; Herz et al., 1989). Mafic-ultramafic assemblages constitute an important component re/ of the Tocantins Province (Almeida et al., 1981; Berbert et al., 1981), particularly along the Florida Elbow Fault: postulated Late Jurassic western margin of the Guaxupe Massif, and are left-lateral strike-slip fault that extends from believed to represent the Brasilian age suture the southern escarpment of the Middle Ground separating the Sao Francisco (+Tocantins- Arch (mga) across Florida to define the north- Guaxupe) Craton from the Amazonian Shield. ern margin of the Great Bahama Bank (Pin- dell, 1985), with ~50 km of motion with re- gP spect to the Middle Ground Arch and ~ 150 km with respect to northern Florida. Guinea Plateau: southern extension of the West African Shelf, characterized by mid-Jurassic g/ rifted margin on the west and a mid-Cretaceous transform margin on the south (Mascle et al., Grenville Front: boundary between regions af- 1986; Jones, 1987) and presumed to be under- fected by the Grenville (peak metamorphism at lain by the northward extension of the Ama- 433 zonian Craton. Tight fit of the Guinea Plateau easternmost extension of Precambrian/Paleo- with the Demerara Rise (dr), and the absence zoic ( ? ) basement to the Yucatan Block. of N-S shortening on either, places severe constraints on the pre-Aptian fit of the equatorial Atlantic margin (Pindell and Dewey, 1982; Pindell, 1985). Kasila Group: Archean (?) retrogressively altered basic, granitic and metasedimentary gs sequences metamorphosed to granulite and almandine-amphibolite facies, including meta- Guinea Shield: pre-Late Proterozoic consoli- morphic equivalents of banded ironstones and dated Archean and Early Proterozoic basement marbles (Williams, 1978). Oldest documented of the West African Craton. Surrounded by Pan- age is a probably unreliable 1.3 Ga (K-Ar on African sutures, including the Pharusian, Da- pyroxene ) but there are several reports of older homeyan, Rokelide, Mauritanide and Adrar (~2.7 Ga) gneisses within it (Cahen and Sottouf sutures. Basement to the Late Precam- Snelling, 1984). Basic and ultrabasic gneisses brian (post ~ 1 Ga) Taoudeni, Tindouf, Rokel, and anorthosites also present to the north and and Volta basins (Cahen and Snelling, 1984). east (Cahen and Snelling, 1984). Kasila Met- amorphics have been retrogressively altered to ic andalusite, sillimanite and cordierite-bearing gneisses and amphibolites during the Pan-Af- Ile de Cayenne Group: Trans-Amazonian gran- rican, which has substantially reset almost all ite-greenstone sequence similar to the Falwa- K-Ar systems within this region (Cahen and tra (afc) and intruded by Trans-Amazonian Snelling, 1984). Inferred to be the northern- syn-kinematic to late kinematic granites (Hur- most basement exposure of the Amazon Shield ley and Rand, 1973). and separated from the Guinea Shield by the Rokelide Suture. imc kmc Imataca Complex: northernmost exposure of Kenema-Man Complex: southern Archean core the Amazon Shield, consists of Archean (3.4- of the Guinea Shield consisting of granite- 2.7 Ga Rb-Sr isochron ages) quartzofeld- greenstone assemblages including the Loko Su- spathic gneisses, amphibolite, iron formation pergroup affected by Leonean ( ~ 2.96 Ga) and and migmatite remobilized during the Trans- overlying Kambui Supergroup affected by Lib- Amazonian with ENE-WSW striking foliation erian (~2.75 Ga) deformations (Cahen and (Hurley and Rand, 1973). Snelling, 1984). /p lo

Isle of Pines Metamorphic Complex: island off Llano Uplift: exposure of Grenville age meta- western Cuba that probably exposes a window morphics (Garrison et al., 1979). through a Cretaceous obducted island arc suite into a sequence characterized by quartzites, m quartzose phyllites, schists, and some marbles that show strong lithologic similarities to the Marathon Mountains: surface exposure of the Pinar del Rio sequence of western Cuba (Pardo, northwest-vergent overthrust Paleozoic off- 1975 ). Interpreted to overlie and/or include the shelf margin facies of southern North America, 434 including Devonian novaculites. Last unequi- Grant, 1973), that juxtaposes an arc complex, vocal exposure of the Late Paleozoic Appala- including Niokolo-Koba, Gamon Granite and chian-Ouachita-Marathon Mountains colli- Simenti Group volcanics and intrusives, and sion zone. Overthrust during the end Bakel-M'Bout and Guidimaka granites and Pennsylvanian (Virgillian) to Early Permian amphibolites that have yielded 4°Ar-39Ar and (Wolfcampian) (Flawn et al., 1961; King, 1975; Rb-Sr ages with a range of 683 to 629 Ma (see Kluth and Coney, 1981 ). review of geology and geochronology by Cahen and Snelling (1984), Dallmeyer and Villeneuve mat (1987) and Dallmeyer (1989)), all part of the Senegal Block, with West African continental Middle America Trench: present day position margin sediments (Grant, 1973; LeCorche et al., of the Middle America Trench developed as a 1983; Dallmeyer and Villeneuve, 1987). Note result of left-lateral transform motion of Late local reactivation and 4°Ar-39Ar resetting of Cretaceous (Campanian-Maastrichtian) to muscovites in mylonitic Simenti granites be- Recent, and concomitant triple junction migra- tween 278 + 1 Ma and 271+ 1 Ma (Dallmeyer tion as the Chortis Block moved into the Car- and Villeneuve, 1987). The Mauritanide Su- ibbean region (Pindell and Dewey, 1982; Pin- ture is inferred to have pre-dated the Rokelide dell and Barrett, 1988). suturing, based on the preservation of older, so- called Pan-African-I ages in the Mauritanides, mfb and only Pan-African-II ages in the Rokelides to the south (Dallmeyer and Villeneuve, 1987; Mauritanide Fold Belt: Late Proterozoic pas- Dallmeyer, 1989). sive margin facies of West African Craton overthrust eastward onto West African Craton during Pan-African suturing with the Senegal rrtsrn Block. Fold belt reactivated at least in the northern Adrar region during post-Famenian Mojave-Sonora Megashear: Pre-Oxfordian times (LeCorche, 1970, as reviewed in Grant, Jurassic left-lateral strike-slip fault that offsets 1973). basement age provinces in the Caborca region of northwestern Mexico (Silver and Anderson, toga 1974) by ~ 700 km. The southeastern extension of this fault is less clear but is generally Middle Ground Arch: basement high bounded extended to the Monterrey region (Anderson on the north by the Bahamas Fracture Zone and Schmidt, 1983). Motion along this fault has (Klitgord et al., 1984) and Florida Elbo Fault been restored in the reconstruction. (Pindell, 1985) presumed to be underlain by crust of Gondwanan (Amazonian Shield?) affinities similar to that which underlies the Su- mt wanee Basin (sb) to the east.

/728 Mixteca Terrane: metamorphic basement assemblage of uncertain Precambrian to Paleo- Mauritanide Suture: Pan-African suture be- zoic age, locally including ultramafics overlain tween the Senegal Block (SNB) and West Af- locally by a deformed Pennsylvanian terrigen- rican Craton ( --Guinea Shield (gs)), defined ous sedimentary section (Campa and Coney, by the serpentinite complex (see review by 1983). 435 mU part of the syn-collisional strain associated with the amalgamation of the Congo Craton (cc), Monroe Uplift: basement high, possibly Benin-Nigeria (bns)-Tuareg Shield (ts), Sao stranded continental remnant of Gondwana Francisco Craton (sfc), West African Craton (Pindell, 1985). ( = Guinea Shield), and Amazon Craton (Black, 1980; Almeida et al., 1981). Reactivated left- laterally (30 km approximate displacement accommodated on Fig. 1 ) during the Late Juras- Ouachita Uplift: surface exposure of the north- sic to Aptian extensional opening of the Recon- vergent Appalachian-Ouachita-Marathon Ov- cavo-Tucano-Jatoba Basin (Mabesoone et al., erthrust Belt, includes Ordovician to Carboni- 1981; Castro, 1987). Formerly continuous with ferous off-shelf slope and rise facies sediments, the Cameroon Shear Zone (csz). including Devonian novaculites, and very thick Carboniferous turbidites derived from the north phfb and east (Graham et al., 1975 ). Ouachitas were overthrust during the Late Pennsylvanian (King, 1975 ), involving a large basement-cored Pharusian-West Hoggar Fold Belt: defines the thrust sheet (Lillie et al., 1983 ). western margin of the Tuareg Shield (ts) and comprises a Late Precambrian arc sequence of (~ 660 Ma) developed above an east-dipping subduction zone prior to the Pan-African Oca Fault: Late Miocene to Recent right-lat- Tuareg-West African Craton collision (Black, eral strike-slip fault that presently defines the 1980). Includes a basement of Archean granu- northern margin of the Santa Marta Block with lites (Ouzzal charnockites and gneisses, meta- ~ 65 km of offset that has been restored in the morphosed at 2.96 Ga) and Early Proterozoic reconstruction (Dewey and Pindell, 1986). granites and migmatites (Black, 1980; Cahen and Snelling, 1984). pafb pn Paraguay-Araguaia Fold Belt: Late Precam- brian (Brasilian=Pan-African) fold belt developed along the eastern margin of the Ama- Pakaraima Nuclei: northwestern cratonic nu- zon Shield (Almeida et al., 1981; Berbert et al., clei of the Amazon Shield, consisting of granitic 1981). Mafic-ultramafic assemblages (ophiol- gneisses and granite-greenstone assemblages ites?) mark the suture along the eastern mar- that are still poorly dated. Separated from the gin of the fold belt with the Tocantins (Guax- Xingu Nuclei by an arm of the Trans-Amazon- upe massif) extension (?) of the Sao Francisco ian Maroni-Itacaiunas Fold Belt (Cordani and Craton). Potentially the southward extension de Brito Neves, 1982 ). of the Rokelide Suture in Africa (Herz et al., 1989). PP p/ Paraguana Peninsula: northernmost exposure Pernambuco Fault: one of the larger right-lat- of at least Paleozoic basement on South Amer- eral Brasilian shear zones to cross-cut the Bor- ica, as indicated by a 265___ Ma U-Pb age on borema Fold Belt (bofb) that accommodated granite (Feo-Codecido et al., 1984). 436 pt pelitic schists and banded iron formation belonging to the Marampa Group (Williams, Piedmont Terrane: predominantly Late Pre- 1978). First identified as a suture by Burke and cambrian and Cambrian clastics deposited on a Dewey (1972) who noted that it continues Grenvillian basement that were deformed and southward as a cryptic suture, and is equivalent metamorphosed to amphibolite facies together to the Brasilian Suture separating the south- during the Paleozoic (Williams and Hatcher, west side of the Sao Luis Craton from the Ama- 1982; Hatcher, 1987). The eastern margin is zonian Craton. Best estimate of the age of de- defined by the Central Piedmont Suture, which formation along the Rokelide Belt is 560 + 19 juxtaposes the Carolina Slate Belt (csb) with Ma, and clearly pre-dates the intrusion of the the Inner Piedmont, and the western margin is Coyah Granite (T) which has yielded a 533 _+ 7 defined by the Brevard Fault, a complex mul- Ma Rb-Sr age (Dallmeyer et al., 1987). tiply reactived fault which separates the Inner Piedmont from the Blue Ridge (b). ru rrns Reguibat Uplift: northern outcrop of the West African Craton, underlain by Archean (~ 2.7 Romeral Suture: defines the western margin of Ga) (Cahen and Snelling, 1984) migmatites in Precambrian and Paleozoic assemblages in the region shown on the map. northwestern South America and juxtaposes these with Cretaceous and younger oceanic arc, 8a glaucophanitic accretionary wedge and ophiolitic assemblages (Etayo-Serna and others, 1983; Sabine Arch: structural high in the basement of Pindell and Barrett, 1988). the Gulf Coast region from which well cores have recovered Mississippian rhyolite (Nicho- ror las and Waddell, 1982; Pindell, 1985, borehole 30), and Desmoinian to Early Permian unde- Roraima Group: unmetamorphosed mid-Pro- formed shallow-water clastics and carbonates terozoic (~ 1.6 Ga) cover sequence of quartz- (Woods and Addington, 1973; Pindell, 1985, ites and quartzitic sandstones with thin rhyol- borehole 31), believed to be correlative (Pin- itic tuffs that overlie ~ 1.9-1.6 Ga acid to dell, 1985) with surface and subsurface Santa intermediate volcanics and outcrop extensively Rosa Group of Yucatan {Lopez Ramos, 1975). in the northern Amazonian Craton (Teixeira et al., 1989). sb r8 Suwanee Basin: undeformed Ordovician to Sil- urian or Devonian marine clastic and shale Rokelide Suture: Pan-African suture separat- dominated sedimentary basin characterized by ing the West African Craton and unconforma- faunas with Gondwanan affinities (Cramer, bly overlying Rokel River Group from compo- 1971, 1973), mid-Proterozoic to early Cam- sitionally different Archean (?) Kasila Gneisses, brian sedimentary provenance (Dallmeyer, here considered to represent the northward ex- 1987; Opdyke et al., 1987), and non-North- tension of the Amazonian Shield. Intervening American Silurian paleolatitude (Opdyke et al., along the suture is a belt of metavolcanics and 1987). Generally correlated with the Bov~ Basin metasediments, including pillow lavas, serpen- succession of West Africa, and used by Wilson tinites, and diorites associated with psammites, ( 1966 ) to suggest that Florida is a fragment of 437

Africa left attached to North America during sl the Mesozoic opening of the Atlantic. Sao Luis Craton: comprises a basement of Early Proterozoic gneisses, migmatites and schists SC that yield Rb-Sr and K-Ar ages in the range 2.2 to 1.7 Ga, covered by slightly deformed Late Sebastopol Complexes: Paleozoic igneous rocks Precambrian (~900 Ma) meta-arkoses (Hur- within the northern Merida Andes that have ley and Rand, 1973; Almeida et al., 1981; Cor- yielded a 425 + Ma Rb-Sr age (Feo-Codecido dani and de Brito Neves, 1982 ). The basement et al., 1984). is equivalent both in lithology and age with the Birrimian (brfb) of the Guinea Shield (Hurley s/c et al., 1967; Hurley and Rand, 1973; Torquato and Cordani, 1981) and the meta-arkoses are Sao Francisco Craton: comprises Archean equivalent with basal sediments in the Rokel ( ~ 3.2-2.7 Ga) granulitic, granite-greenstone River Group and Tossiegou Formation of the terrane, cross-cut by various Wrans-Amazon- Dapango-Bombouaka Group of the Volta ian (~2.0 Ga) (Salvador-Juazeiro (east)and Basin. Bounded on the south by Brasilian age Correntina-Guanambi (west) foldbelts), mid- fold belt characterized by NW-SE striking fol- Proterozoic ( ~ 1.2 _+ 0.1 Ga) (Espinhaco Fold iation in metasediments and metavolcanics and Belt) covered by relatively undeformed and assumed to be the along-strike continuation of unmetamorphosed mid-Proterozoic (Chapada the Rokelide Orogen. Diamantina) and Late Precambrian (Bambui, Una, and Estancia groups) sediments. The sfc slc is surrounded by Brasilian age fold belts associated with the Late Precambrian amalgama- St. Lucie Metamorphic Complex (Thomas et tion of the West Gondwanan cratons (Almeida al., 1987): Pan-African deformed and meta- et al., 1981; Wernick, 1981; Cordani and de Brito morphosed amphibolite, biotite-muscovite Neves, 1982). schist and gneiss, and quartz diorite (Dall- meyer, 1989). Well-defined hornblende 4°Ar- 39Ar plateau ages of 513 and 511 Ma are re- s/z ported for this complex by Dallmeyer (1989).

Swan Fracture Zone: Campanian-Maastrich- $m tian to Recent left-lateral transform connect- ing the Middle America Trench to the mid- Santa Marta Fault: transpressional left-lateral Cayman spreading center (see Pindell and Bar- strike-slip fault that defines the present west- rett, 1988). Total strike-slip motion is ~ 1150 ern margin of the Santa Marta Block (SMB), km which has been accounted for in the recon- with ~ 110 km of Late Miocene to Recent mo- struction, 950 km of which is associated with tion that has been restored in the reconstruc- Eocene to present-day seafloor spreading in the tion (Dewey and Pindell, 1986). Cayman Trough (Rosencrantz et al., 1988). Motion along this fault is responsible for the smt offset of the Paleozoic metamorphics of northeastern Chortis Block (Horne et al., 1976) from Sierre Madre Terrane (Campa and Coney, their equivalents in the Xolapa Terrane (xt) of 1983): includes a basement gneiss that has southern Mexico. yielded a 0.9 Ga Sm-Nd model age (Ruiz et al., 438

1987 ), unconformably overlain by thin platfor- eyan basement of the Benin Plain) and West mal sequence of Cambrian(?) and Ordovi- African Craton. Represents passive margin cian (?) quartzite, conglomerate and siliceous shelf to rise and syn-Pan African flysch se- limestone, Silurian deeper-water carbonate and quence overthrust westward onto the Volta shale containing transported shallow-water Basin. Bounded on the east by ophiolitic as- fossils, Devonian (?) volcanics that were pre- semblages that mark the suture, serpentinitic viously interpreted as novaculite (see discus- and spilitic fragments (?) of which are locally sion in Stewart, 1988), Lower Mississippian and preserved within the Buem Sequence (Black, Lower Pennsylvanian sandstones and shales, 1980; Affaton et al., 1980; Cahen and Snelling, and sandstones, shales and carbonates, respec- 1984). tively, and a much thicker sequence of Permian interbedded sandstones and shales (flysch) tmvb (Lopez Ramos, 1982; Campa and Coney, 1983 ). Sequence interpreted to be equivalent to the Trans-Mexican Volcanic Belt: E-W striking Oaxaca ( = western Venezuela and Colombia), belt of Oligocene and younger volcanics and and therefore to represent facies derived from volcaniclastics that are assumed to overlie an northern South America. older Jurassic left-lateral strike-slip fault (Walper, 1980; Dickinson and Coney, 1980) ta with ~-75 km of motion which has been accounted for within the reconstruction. Tampa Arch: Gulf Coast basement high south of the Florida Elbow Fault (fef), from which ts two boreholes (Pindell, 1985, boreholes 28, 29 ) have recovered pre-Jurassic (?) granodiorite Tuareg Shield: includes a basement of Archean and granite, respectively. granulites (Ouzzal charnockites and gneisses metamorphosed at 2.96 Ga), Early Proterozoic tb granites and migmatites, Late Proterozoic Sto- matolite Series and overlying Late Precam- Taoudeni Basin: Late Proterozoic ( ~ 1 Ga) to brian arc volcanics and their associated plutons Cambrian(?) platform and cover sequence, (Black, 1980; Cahen and Snelling, 1984). As- thickening into passive margin sequences both sumed to be continuous in the subsurface with to the east in the Gourma Aulocogen (see Black, the Benin-Nigeria Shield to the south. 1980) and to the west in the Mauritanide Fold Belt. Relatively widespread Late Ordovician tsb glacial tillites followed by thin Silurian, Devon- ian and somewhat thicker ( ~ 600 m), but more Talladega Slate Belt: greenschist facies slate restricted, Carboniferous (only along northern and marble assemblage of Late Precambrian to margin away from Mauritanide Fold Belt) Devonian age that is the facies equivalent of the (Dillon and Sougy, 1974; Cahen and Snelling, Appalachian platform stratigraphy exposed to 1984). the west (Tull et al., 1985; in Hatcher, 1987). tba vb

Togo-Buem-Atacora Fold Belt: Pan-African Volta Basin: Late Proterozoic platformal to fold belt developed as a result of the collision shelf equivalents of the Togo-Beum-Atacora between the Benin-Nigeria shield (Dahom- (tba) margin sequence to the east. Unconform- 439 ably overlies Early Proterozoic Birrimian and Eburnian=~2.1-2.0 Ga) basement uncon- infolded Tarkwaian basement (brfb) and in- formably beneath the West Congolian Super- cludes Late Precambrian Depango-Bom- group (Cahen and Snelling, 1984). Suture be- bouaka Group clastics, Pendari Group tillites, tween the Congo Craton and Sao Francisco shelf carbonates, cherts and phosphorites, and Craton must lie west of the coastline. thick (2.5-4 km), syn-Pan-African flysch and Late Precambrian to Cambrian (?) Obosum Group molasse (Affaton et al., 1980). Xingu Nuclei (Cordani and de Brito Neves, /Jr 1982 ): approximately equivalent to the Central Amazonian Province of Teixeira et al. (1989). Valley and Ridge Province: foreland style, west- Includes the Archean ( > 2.5 Ga, though poorly vergent fold-thrust belt involving primarily dated) core of the Amazon Craton, consisting Paleozoic sediments of North American plat- of high-grade granitic gneisses and granite- form and shelf facies (Rodgers, 1970) associ- greenstone terrane (Cordani and de Brito ated with the overthrusting of the basement- Neves, 1982, Teixeira et al., 1989 ). Unconform- cored Blue Ridge and Piedmont assemblages ably overlain by greenschist facies basaltic to (Cook et al., 1979). Deformation of the Valley rhyolitic metavolcanics, followed upwards by and Ridge occurred predominantly in the Car- banded iron formation and terrestrial sedi- boniferous, though it was still active in the Early ments. The metavolcanics and iron formation Permian (Rodgers, 1970; Thomas, 1985). have yielded ~ 2.7 Ga U-Pb ages, whereas K- Ar mica and amphibole ages range from 3.3 to wa 1.75 Ga (Teixeira et al., 1989).

Wiggins Arch: basement high from which gran- xt ite and phyllites have been recovered that have yielded metamorphic ages ranging from 325 to Xolapa Terrane: generally migmatitic meta- 270 Ma (see citations in Pindell, 1985, borehole morphic-plutonic complex that in general yields 32). 4°Ar-39Ar hornblende and biotite ages from young, Jurassic to Tertiary isotopic ages higher grade assemblages yield plateau ages of {Campa and Coney, 1983 ), but is generally as- 310 and 305 Ma, respectively, reflecting sub- sumed to include older Paleozoic and Precam- stantial Alleghenian reheating (Dallmeyer, brian (?) assemblages (Lopez Ramos, 1981 ). 1989). References wcfb Affaton, P., Sougy, J. and Trompette R., 1980. The tecto- West Congolian Fold Belt: Pan-African oro- nostratigraphic relationships between the Upper Pre- genic belt developed on the western margin of cambrian and Lower Paleozoic Volta Basin and the Pan- the Congo Craton. East part is an east-vergent African Dahomeyide orogenic belt. Am. J. Sci., 280: 224- 248. fold-thrust belt involving a Late Precambrian Almeida, F.F.M., de Amaral, G., Cordani, U.G. and Ka- (~ 1.0-0.7 Ga) sedimentary sequence depos- washita, K., 1973. The Precambrian evolution of the ited unconformably over the Congo Craton, and South American cratonic margin south of the Amazon representing a westward thickening passive River. In: A.E.M. Nairn and F.G. Stehli {Editors), The margin section (West Congolian Supergroup). Ocean Basins and Margins. 1: The South Atlantic. Plenum, New York, pp. 411-446. Western part characterized by a Pan-African Almeida, F.F.M. de, Hasui, Y., De Brito Neves, B.B., and remobilized Early Proterozoic (Tadilian-- Fuck, R.A., 1981. Brazilian structural provinces: An 440

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