Abstract The stratigraphy, structure and hydrocarbon potential of the deep-water Yucatan margin remains less understood than other margins of the Gulf of Mexico (GoM), as Yucatan has not been systematically mapped and has few well penetrations. Despite the presence of widespread oil slicks along the continent–ocean boundary, the maturity and distribution of source rock kitchen areas have not been well defined. This study uses a grid of 2D post-stack depth migration (PSDM) seismic profiles covering an area of approximately 120 000 km 2 to map the structure and stratigraphy, and to model thermal maturities of three potential Mesozoic source horizons. Thermal 1D modelling of six pseudo-wells, positioned along a dip profile, was performed using estimates of lithospheric thickness and thermal properties. Integrated 3D model results indicate that the principal Tithonian-age source rock reached the oil window within the diapiric salt province during the Oligocene–Miocene. Inherent model uncertainty was addressed using a range of thermal scenarios. The result of modelling was that deeply-buried, salt-related minibasins along the outer marginal trough are low risk and the uppermost slope is high risk for maturity. Large, salt-related structural traps are directly adjacent to oil kitchens within deeply-buried minibasins. Normal faults bounding minibasins provide effective vertical migration pathways as supported by the clustering of overlying oil slicks.

Abstract Thick sedimentary cover (≤16 km), vintage seismic and disparate crustal terranes have hindered understanding of the basement underlying the Caribbean plate. The plate formed by Early Cretaceous to Miocene amalgamation of four crustal types: the Caribbean Large Igneous Province oceanic plateau; the Chortis continental block; the related Great Arc of the Caribbean and Siuna/Mesquito Composite Oceanic Terranes island arc blocks; and the Colombian and Venezuelan basin oceanic crust. We characterize each terrane through interpretation of surface geology, 62 000-line-km of 2D seismic reflection data, 366 seismic refraction stations, 47 wells, 74 basement samples, 2D forward modelling, magnetic and gravity anomaly grids, and integration of previous studies. Basins overlying island arc crust are small, fault-bounded and deep, while on continental crust, they are broader and shallower. Strongly flexed oceanic and oceanic plateau crust along amagmatic subduction zones on the southern and northeastern edges of the Caribbean plate produce the largest and deepest sediment-filled basins. Areas of proven hydrocarbon source rocks and mapped seeps are associated with continental and island arc terranes in the western Caribbean plate, while organically-rich, but immature, Late Cretaceous source rocks occur across the more elevated areas of the central and eastern Caribbean plate interior.

Abstract Active tectonic deformation and seismicity of Hispaniola define a 250 km-wide, oblique collisional zone between the Bahamas, the island arc of Hispaniola and the Caribbean Large Igneous Province (CLIP). To reflect how collision is accommodated within Hispaniola, we calculate river normalized steepness and terrain surface roughness to reveal the areas of the most active uplift within central and western Hispaniola compared to eastern Hispaniola. We use gravity modelling to show thickness variations in the main crustal types in the obliquely convergent zone: (1) 33–45 km-thick arc crust in central and western Hispaniola; (2) 15–25 km-thick oceanic crust beneath the Bahamas north of Hispaniola; (3) 5–8 km-thick Atlantic oceanic crust NE of Hispaniola; and (4) 6–16 km-thick CLIP south of Hispaniola. Intermediate to deep earthquakes beneath eastern Hispaniola indicate active southwestward subduction of normal oceanic crust and northward subduction of the CLIP. We interpret that the west-to-east geomorphological and crustal variations within Hispaniola to be the result of an along-strike transition from crustal shortening without subduction between the Bahamas and arc crust in central and western Hispaniola to subduction of the North American and Caribbean plates beneath eastern Hispaniola. Crustal shortening in central and western Hispaniola produces thrust-fault-bounded basins with sufficient clastic sedimentary infill to produce hydrocarbon maturity.

Abstract Over 72 exploration wells have been drilled on the Caribbean islands of Hispaniola and Puerto Rico over the past century, but with no commercial success. A question is whether these Caribbean oceanic islands have experienced sufficient subsidence and burial for any potential source rocks to reach maturity and produce commercial hydrocarbons. Subsurface data from previous studies were compiled into a regional depth to basement and sediment thickness map for Hispaniola, Puerto Rico and their offshore areas. The thickest basins include the Enriquillo/Cul-de-Sac basin (6.3 km), San Juan/Plateau Central basin (5 km), Azua basin (2.8 km), Cibao basin (5 km), North Coast basin (2.5 km), South Coast basin (1.3 km), Haiti sub-basin (3.7 km), Hispaniola basin (3.5 km) and San Pedro basin (3 km). One-dimensional modelling for six onland basins shows that only the Azua basin of the south-central Dominican Republic has reached sufficient maturity to place potential source rocks into the oil window. Our study shows that commercial hydrocarbons are possible in the deeper basins – Azua basin, San Juan–Plateau Central basin and Cibao basin of Hispaniola – but unlikely in the shallower basins that lack sufficient overburden for organic maturity.

Abstract Oil seeps and small-production oilfields in south-central Hispaniola are regionally isolated from much larger hydrocarbon provinces in the circum-Gulf of Mexico and northern South America. In this study, we evaluate the tectonic, stratigraphic and structural setting of these hydrocarbon occurrences. The zone of late Miocene to Recent oblique convergence includes the Bahamas Platform, Cretaceous and Paleogene arc rocks in Hispaniola, and the Cretaceous Caribbean oceanic plateau. Twentieth-century hydrocarbon exploration in Hispaniola has been concentrated on the elongate, NW- to WNW-trending, thrust- and strike-slip fault-bounded Cibao, San Juan–Azua and Enriquillo basins. Analyses of Cretaceous to Neogene rocks in the Dominican Republic have revealed that most rocks contain poor to marginal total organic carbon values. In the Azua Basin, a shallow marine, basin-edge facies of the middle Miocene Sombrerito Formation underlies the area of natural oil seeps and limited historical oil production and exhibits good to excellent total organic carbon values greater than 1%. Structural traps for oil at the Maleno and Higuerito oilfields of the Dominican Republic are large anticlines formed in post-late Miocene time. Reservoir rock for oil at the Maleno and Higuerito oilfields of the Dominican Republic is submarine fan-deposited sandstone of the late Miocene Trinchera Formation.

ABSTRACT The 2009 discovery of the 17 tcf, thermogenic, Perla giant gas field in the Gulf of Venezuela (GOV)—which is hosted in a 240 m (787 ft) thick red algal carbonate reservoir of late Oligocene–early Miocene age—stimulated a more regional re-evaluation of potentially large, Cenozoic carbonate reservoirs along the continental margins and accreted Caribbean arc terrane of northwestern South America. This chapter focuses on describing the petroleum potential of early Miocene carbonate reservoirs of the La Vela Basin (LVB) of offshore, western Venezuela that is located 100 km (60 mi) east of the La Perla gas giant. Our subsurface data for the LVB—which was kindly provided by the Venezuelan National Oil Company (Petroleos de Venezuela, S.A., or PDVSA)—include a basinal-scale database of 1100 km 2 (680 mi 2 ) of 3-D seismic data that are tied to 52 wells. We use these data to assess 143 m (470 ft) thick, coralline, carbonate reservoirs of the LVB of early Miocene age that have produced minor amounts of oil and gas since the 1970s. Additional oil and gas producing reservoirs of the LVB include fractured and metamorphosed basements of Neoproterozoic, Permian, and Cretaceous age that are exposed on the adjacent Paraguana Peninsula and have been previously sampled and radiometrically dated from both outcrops and cores of wells drilled into basement of the LVB. We integrate gravity and magnetic data to map the three types of crystalline basement that underlie the LVB. We use the seismic well data to define orientations and types of faults, thickness variations, and sedimentary facies of the main carbonate reservoirs unit (early Miocene Cauderalito Member of the Agua Clara Formation). We compare the characteristics of the coralline La Vela carbonate reservoirs with known late Oligocene–early Miocene, red algal, carbonate ramp settings of the Gulf of Venzuela (Perla gas giant) and the early Miocene, San Luis red algal ramp of the onshore, Falcon Basin (FB). The most prospective carbonate reservoirs are red algae-based and are related to their distinctive ecological and tectonic settings.

ABSTRACT Kinematic analysis of faults in Trinidad reveals three main stages of the tectonic evolution of the southeastern Caribbean–South American plate boundary. During Stage 1, folding and thrusting occurred and are truncated by a Middle Miocene unconformity. This shortening event has been related by previous workers to the initial, oblique collision of the Great Arc of the Caribbean with the passive margin of South America. We propose that Stage 1 Middle Miocene east-northeast-trending compression documented in this study initially had a more northwest–southeast direction and has been rotated in a clockwise direction during this collision. This tectonic stage resulted in clockwise rotation of structures along the southeastern Caribbean plate margin within a broad, right-lateral, strike-slip zone. During Stage 2 in the late Miocene and middle Pliocene, south-southeast-trending shortening uplifted the Central Range, formed prominent north-dipping thrusts, bounded by oblique ramps such as the Los Bajos right-lateral strike-slip fault and formed piggy-back basins. This north-northwest– south-southeast trend of compression is compatible with coeval right-lateral shear on the El Pilar fault zone in Trinidad. We interpret this pattern of coeval thrusts and strike-slip faults of Stage 2 as the result of strain partitioning. In Stage 3 during the late Pliocene– Quaternary, the stress field rotated counterclockwise and east-southeast-trending compression reactivated previous thrusts as right-lateral, strike-slip faults, such as the Central Range fault. The rotation of the trend of compression deactivated previous, east–west-trending, strike-slip faults such as the eastward extension of the El Pilar fault zone into Trinidad. The polyphase tectonic evolution of Trinidad occurs in the regional context of the eastward motion of the Caribbean plate with propagation of the southern Subduction-Transform Edge Propagator (STEP) fault.

ABSTRACT The subduction-to-strike-slip transition (SSST) zone of the southeastern Caribbean is one of the thirty identified locations where active subduction and strike-slip tectonic styles transition along strongly curved and seismogenic plate boundaries. We use approximately 10,000 km (6000 mi) of 2-D seismic reflection, well, seismic tomographic, gravity, magnetic, earthquake focal mechanisms, and global positioning system (GPS) data to study the primary structures within the SSST zone. We analyze transitions of subducted slabs, basement areas, sedimentary basins, faults, and other structures from an area of westward-directed subduction of Atlantic oceanic crust beneath the Lesser Antilles arc, to a region of east–west-striking, right-lateral strike-slip faulting along the northern South American margin. Tectonic processes in the arcuate plate boundary zone include (1) oblique collision between the arcuate front of the Caribbean plate and the northern South American margin; (2) propagation of the Subduction-Transform Edge Propagator (STEP) fault as defined by Govers and Wortel (2005) ; and (3) north-to-northwest flexure of transitional South American lithosphere as the slab detaches from the South American continent, tears apart from the west-dipping segment of the slab to the north, and sinks into the mantle beneath the Caribbean plate. Northwest–southeast-oriented Atlantic oceanic fracture zones, and lithospheric transitional boundaries are a significant control on the evolution of the margin including the location and orientations of STEP faults, slab rollback, detachment, and tearing. Lithospheric deformation associated with STEP tearing and slab detachment influences the position, orientation, and evolution of crustal plate boundary structures and sedimentary basins discussed in more detail in Chapter 5 ( Alvarez et al., 2021 ). Sedimentary basins and structures of the southeastern Caribbean SSST zone are characterized by spatially and temporally complex uplift and subsidence patterns at the surface, which are the result of the multiphase deformational history that includes oblique collision, STEP faulting, and subducted slab dynamics, which are inherent to the bounding tectonic configuration.

ABSTRACT The Espino rift of north-central Venezuela is a 60–100 km (35–60 mi) wide, 250 km (155 mi) long, symmetrical, subsurface rift that formed in the Cambrian–Ordovician and underwent a second phase of rifting during the Late Jurassic breakup of Pangea. During the Oligocene and Miocene, normal faults bounding the Espino rift were more strongly inverted at its northern end by right-lateral transpression between the eastward-moving Great Arc of the Caribbean (GAC) and the northern margin of South America. During the Oligocene to Holocene, the Espino rift became deeply buried beneath clastic sedimentary rocks of the Eastern Venezuela foreland basin. We apply filters to gravity and magnetic data from the region of the Espino rift in central Venezuela to delineate the crustal setting of the rift. We use three 2-D gravity transects combined with five seismic reflection transects tied to 12 wells to reconstruct the multistage geologic and structural evolution of the Espino rift from its initial rift phase in the Cambrian–Ordovician, through its subsequent latest Jurassic period of rifting, and its final period of Oligocene–Miocene transpression related to the oblique collision of the GAC with northern South America. Because there is no direct well evidence for the type and age of basement underlying the Espino rift, our gravity and magnetic transects provide new observations on crustal thickness variations across and along the rift, which ranges from 13 to 30 km (8–19 mi). Gravity modeling also reveals a variation in Moho depths from approximately 30 km (19 mi) on its rift flanks to 24–29 km (15–18 mi) beneath the rift axis. These data constrain the subsurface extent of the rift that can be traced for 200 km (125 mi) along-strike with three main segments: (1) a shallower rift in the south (top basement buried 1.8 km [5905 ft] beneath the rift axis), (2) the deepest, central rift area (top basement buried 12 km [39,370 ft] beneath the rift axis), and (3) a zone of Cenozoic tectonic transpression in the northern rift area (top basement buried 10 km [32,800 ft] beneath the rift axis). Based on wells and seismic reflection data, we conclude that the Cambrian–Ordovician rift phase was accompanied by a greater degree of crustal thinning than the Late Jurassic rift phase. The northwest–south extension direction remained the same for both rifting events.

ABSTRACT The Eastern Venezuelan foreland basin (EVB) has been filling from the southwest by the Orinoco River since the late Miocene–early Pliocene. The easternmost part of the Eastern Venezuelan Basin (EEVB) became overfilled by clastic sedimentation since the Pliocene. The EEVB now consists of a 10 km (33,000 ft) thick delta system formed by the Orinoco River, which has spilled over the shelf edge onto the Atlantic margin of northeastern Venezuela. The Eastern Venezuelan foreland basin is the second largest hydrocarbon-producing basin in Venezuela, with proven reserves of 36 billion barrels. To improve our understanding of the paleogeography and hydrocarbon potential of the EEVB, 620 km 2 (385 mi 2 ) of 3-D seismic, 4000 km (2485 mi) of 2-D seismic, and six wells with well logs were interpreted from the Punta Pescador area of the EEVB. We integrate the results from this study with the results of previous workers around the Orinoco Delta. Based on the integration of these data, the following sequence of Cenozoic events affecting the study area are proposed: (1) passive margin setting since the Cretaceous to Paleogene; (2) oblique collision of the Caribbean plate causing an underfilled, foreland basin stage that initiated during the late Oligocene; (3) during the Oligocene and early Miocene, south–north-flowing fluvial systems and associated deltas prograded northward and filled the foreland-basin-related depocenter; (4) late Miocene eustatic sea level lowering produced a major erosional surface and submarine canyons that allowed sediments to suddenly prograde eastward; and (5) early Pliocene to Holocene overfilling of the EEVB with eastward progradation of the Orinoco Delta into the Atlantic Ocean. Using the new information presented in this chapter, several hydrocarbon prospects were identified within the clastic Miocene–Pliocene–Pleistocene sequence.

ABSTRACT This study presents an integrated, mega-regional, subsurface synthesis of the southeastern Caribbean plate margin that incorporates observations from gravity, seismic refraction, outcrop, and approximately 20,000 line-km of high-resolution 2-D seismic reflection data tied to wells. The primary objective of the study is to better understand the tectonic and basinal transitions from the Lesser Antilles subduction zone (LASZ)—characterized by the subduction of the South American oceanic crust beneath the overriding Caribbean plate and the approximately 300-km (185 mi)-wide, deepwater Barbados accretionary prism (BAP)—to the arcuate, obliquely convergent, and transpressional southeastern Caribbean–South American plate boundary zone—characterized by a complex suite of uplifted provinces, foreland basins, and hybrid sedimentary basins. Early Cretaceous aged allochthonous arc terranes, including the island of Tobago and its offshore component, the Tobago–Barbados Ridge (TBR), were accreted along the deeply buried, lithospheric trace of the LASZ and tectonically transported eastward for hundreds of kilometers along northern South America to their present-day position at the leading eastern edge of the Caribbean plate. Along-strike changes in structures of the BAP are related to progressive phases of deformation that involve thickening of prism strata against the TBR-controlled backstop, frontal accretion that forms the main body of the BAP, horizontal shortening, mud diapirism, rotation and uplift of structures, and backthrusting at the western edge of the prism. The Galera Tear fault zone (GTFZ) formed along the Mesozoic continent–ocean boundary (COB) of the northeastern South American plate. The GTFZ accommodates the differential deformation between provinces of the BAP within the LASZ to the northeast and provinces of the oblique collision and strike-slip zone near Trinidad. Basins affected by subduction-to-strike-slip plate boundary interaction undergo superimposed areas of compressional–transpressional, extensional–transtensional, and strike-slip deformation.

ABSTRACT The North Coast Marine Area (NCMA) extends across approximately 7000 km 2 (4300 mi 2 ) of the northern Trinidad and Tobago shelf in water depths between 50 and 200 m (165–655 ft). In 2009, the NCMA had two exploration blocks under active oil and gas exploration with gas production from the NCMA totaling approximately 1.1 tcf since 2002. The NCMA is located within a complex, tectonic environment characterized by oblique, right-lateral–strike-slip displacement between the Caribbean and South American plates moving at a rate of about 20 mm/yr. This study analyzes two Pleistocene, fourth-order, shelf, and shelf-edge stratigraphic sequences (sequences B and C) deposited over the past approximately 500 k.y. in the western part of the NCMA. Micropaleontologic well data through Sequences B and C constrain the basal deposition to have initiated at ~500 k.y. and ~125 k.y., respectively. The lithologic interpretation from well log analysis tied to the seismic data shows these sequences composed of sand, shale, and thin limestone. Seismic interpretation allows division of both Sequences B and C into eight system tracts, which include (1) lowstand, (2) transgressive, (3) highstand, and (4) falling stage. The Sequences B and C lowstand systems tracts are characterized by subaerial or subaqueous delta top deposition from the paleo-Orinoco River as it prograded northward through the narrow region known as the Dragon’s Mouth on the northwestern side of Trinidad. The falling stage systems tract of Sequence C consists of a package of approximately 20–45-m (65–150 ft)-high, 0.1°–0.25°-inclined, and northeastward-prograding muddy, shelf-deltaic clinoforms whose northward termination marks the paleoshelf edge. Normal and strike-slip faults deform Sequence B and produced accommodation space to thieve sediment, and inhibit the extent of progradation and subsequent gravity deposition off the delta front. Faults do not penetrate into overlying Sequence C whose deposition was more eustatically controlled. These Pleistocene sequences provide an analog for underlying Miocene and Pliocene age sequences and reservoirs that form the most productive, NCMA gas fields.

ABSTRACT The Trinidad region of the southeastern Caribbean is a tectonically complex subduction-to-strike-slip plate boundary transition where distinct changes in the style, size, and orientation of sedimentary basins and uplifted structures occur over short distances measured in kilometers to tens of kilometers. We interpret approximately 10,000 km (6000 mi) of deep-penetration 2-D seismic reflection and well data to map the distribution and continuity of tectono-stratigraphic sequences and to constrain the timing of structures related to basin formation and deformation. The along-strike, plate boundary transition from subduction to strike-slip is documented in the stratigraphic record by differences in the style and deformation in basins overlying South American basement. At the Lesser Antilles subduction margin, the approximately 300-km (180-mi)-wide Barbados accretionary prism (BAP) is situated greater than 1200 m (3900 ft) below sea level. The BAP is characterized by approximately parallel, forward-breaking thrusts overlain by small, semi-isolated piggyback basins and is associated with mud diapirism. The BAP formed above, approximately 5–7-km (16,400–23,000-ft)-thick subducting Atlantic oceanic crust of Jurassic to Early Cretaceous age. In the oblique-collisional and strike-slip zone onshore Trinidad, there is a less than 100-km (60-mi)-wide zone of middle Miocene folding and thrusting cut by later strike-slip deformation—with maximum elevations of 940 m (3000 ft) above sea level. This complex fold-and-thrust-belt includes elevated, anticlinal ranges with intervening synclinal basinal areas. The northwest–southeast-oriented Galera Tear Fault Zone (GTFZ) is a location of incipient lithospheric tearing that is aligned with the boundary between continental crust of South America—which experienced oblique collision and translation—and orthogonally subducting South American (Atlantic) oceanic crust. The southeast Caribbean margin presents a unique opportunity to observe the phases of deformation, which are responsible for complex and superimposed deformation structures in the rock record along the northern South American margin. These deformational phases have developed progressively as the arcuate, eastward-advancing front of the Caribbean plate interacts with northern South America. This study represents progress in the understanding of sedimentary basins and deformation structures, which form and evolve at the Caribbean–South American plate boundary zone with implications for geologic interpretation and petroleum systems evaluation in older segments of the northern South American, and other hybrid subduction-to-strike-slip plate boundary margins.

ABSTRACT The seafloor of the North Coast Marine Area (NCMA) includes approximately 7000 km 2 (~2700 mi 2 ) of the northern Trinidad and Tobago shelf that ranges in water depths between 50 and 200 m (160–655 ft). The NCMA is an important natural gas province located within a seismically active, strike-slip, plate boundary zone characterized by oblique, strike-slip displacements between the Caribbean and South American plates at a rate of about 20 mm/yr. The main faults of the 200 km (125 mi) wide plate boundary zone include (1) the El Pilar right-lateral–strike-slip fault zone to the south of the Araya–Paria Peninsula and the Northern Range of Trinidad; global positioning system (GPS)-based geodesy has shown that this fault in Trinidad is largely inactive; (2) the North Coast fault zone (NCFZ), which coincides with the southern boundary of the Tobago basement terrane and is active with down-to-the-north, Miocene to Holocene oblique-slip movements that produce accommodation space for deposition for mainly sedimentary rocks along the northern shelf of Trinidad and Tobago; and (3) the subvertical, right-lateral, 120-km (75 mi)-long Hinge Line fault zone (HLFZ) bisects the NCMA in a direction subparallel to the GPS-determined, 80° direction of Caribbean plate motion and forms the main topic of this chapter. Localized zones of transpression and transtension form locally where the trace of the fault deviates from the 80° direction of pure, right-lateral Caribbean plate motion known from GPS studies. Localized areas of complex strike-slip and normal faults and folds provide important structural traps for Pliocene and Miocene gas reservoirs in the NCMA along the deformed northern flank of the HLFZ, where production over the past 15 years has totaled more than 1.1 tcf of biogenic gas. Growth sequences along the HLFZ indicate that the HLFZ activated in Miocene and remains active to the present day as shown by localized scarps on the seafloor.