Abstract The San Pedro Basin (SPB) is located at the southeastern margin of Hispaniola Island (Dominican Republic and Haiti). It is the largest offshore basin of the Dominican Republic with an extension of 6000 km 2 . The basin has a maximum water depth of 1600 m and is positioned to the rear of the Muertos Thrust Belt (MTB). The SPB is bounded to the west by the Azua Basin which has a proven petroleum system and small oil production has been recovered from the Maleno and Higuerito fields. While in the scientific literature the SPB and the Azua basins have been considered as disconnected sedimentary systems, our current study suggests both that shared a common tectonic evolution and therefore the presence of an untested petroleum system in the SPB can be expected. We have carried out a detailed review and synthesis of the onshore systematic geological mapping (the SYSMIN I and II programmes) together with the integration of a large volume of subsurface geophysical data. This includes analysis of 60 exploration wells provided by Banco Nacional de Datos de Hidrocarburos (BNDH) of the Dominican Republic, processing of new 2D multi-channel seismic data from the Spanish Research Project NORCARIBE, reprocessing of legacy seismic profiles, and interpretation of gravity and magnetic data. Our results have led us to propose a new evolution model for the SPB. The basement of both basins consists of Cretaceous sedimentary and volcanic rocks of intra- and back-arc settings. A change in the stress regime in the Campanian led to partial inversion of the basement units favouring the deposition of two main sequences of Campanian–Maastrichtian and Paleocene?–Eocene age in a submarine foreland setting. Due to collision between the Carbonate Bahamas Province and Hispaniola in the middle Eocene, compressional stresses were transferred to the south where Cretaceous and Paleogene sediments were deformed, forming the current configuration of the MTB and generating a new accommodation space where the SPB has developed since upper Eocene–Oligocene until Present. While the Azua Basin was finally exhumed after the Miocene–Pliocene, most of the SPB continued as an actively subsiding basin. This new model has allowed identification of the main elements of the petroleum system in the SPB: a mature Upper Cretaceous source rock; and Oligocene–Miocene carbonate and clastic reservoirs interbedded with sealing shales and marls. Main traps (structural and stratigraphic) are of Oligocene–Miocene age and their formation seems to be synchronous to oil generation. While the main elements of the petroleum system seem to be present in the basin, timing is a key issue that must be addressed and assessed in any future exploration in the basin.

Abstract The intraplate Cameros Rift Basin in northern Spain, which has sediments some 6500 m thick, developed between the Late Jurassic and Early Albian. Its facies and their distribution in the sedimentary record suggest the basin may contain hydrocarbon systems. The arenite composition of the basin reveals two main petrofacies: (1) a quartzolithic petrofacies, the provenance of which is related to recycling processes that took place in the pre-rift sedimentary cover; and (2) a quartzofeldspathic petrofacies mainly related to the erosion of a plutonic and metamorphic source of arenite. The succession of these petrofacies reflects two main cycles representing the progressive erosion of their sources, one of 10 Ma, the other of 30 Ma. Such succession is typical of a non-volcanic rift basin. The quartzolithic petrofacies shows early carbonate cements that inhibited compaction and later quartz, feldspar and clay mineral diagenetic phases. The quartzofeldspathic petrofacies has a rigid framework that maintained the original pores of the arenite during burial diagenesis. Quartz and K-feldspar overgrowths are common, with secondary porosity occurring as a product of feldspar dissolution. The quartzofeldspathic petrofacies has a greater potential to act as a hydrocarbon reservoir. This study corroborates the close relationship between the provenance of arenite and its reservoir potential in continental rift basins.

Following the Variscan orogeny, the Iberian plate was affected by an extensional tectonic regime from Late Permian to Late Cretaceous time. In the central part of the plate, NW-SE–trending rift basins were created. Two rifting cycles can be identified during the extensional stage: (1) a Late Permian to Hettangian cycle, and (2) a latest Jurassic to Early Cretaceous cycle. During these cycles, thick clastic continental sequences were deposited in grabens and half grabens. In both cycles, sandstone petrofacies from periods of high tectonic activity reveal a main plutoniclastic (quartzofeldspathic) character due to the erosion of coarse-grained crystalline rocks from the Hesperian Massif, during Buntsand- stein (mean Qm 72 F 25 Lt 3 ) sedimentation and during Barremian–early Albian times (mean Qm 81 F 18 Lt 1 ). Geochemical data show that weathering was more intense during the second rifting phase (mean chemical index of alteration [CIA]: 80) due to more severe climate conditions (humid) than during the first rifting phase (mean CIA: 68) (arid climate). Ratios between major and trace elements agree with a main provenance from passive-margins settings in terms of the felsic nature of the crust. However, anomalies in trace elements have been detected in some Lower Cretaceous samples, suggesting additional basic supplies from the north area of the basin. These anomalies consist of (1) low contents in Hf, Th, and U; (2) high contents in Sc, Co, and Zr; and (3) anomalous ratios in Th/Y, La/Tb, Ta/Y, and Ni/V. Basic supplies could be related to the alkaline volcanism during Norian-Hettangian and Aalenian-Bajocian times. Geochemical composition of rift deposits has been shown to be a useful and complementary tool to petrographic deduction in provenance, especially in intensely weathered sediments. However, diagenetic processes and hydrothermalism may affect the original detrital deposits, producing changes in geochemical composition that mislead provenance and weathering deductions.