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Third HGS and EAGE Conference on Latin America
- Conference date: November 8-10, 2021
- Location: Online
- Published: 08 November 2021
21 - 25 of 25 results
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The BSR Black Swan Effect
Authors K. Rodriguez and N. HodgsonSummarySummary is not available.
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Enhanced Salt Imaging Offshore Mexico
Authors K. Rodriguez and N. HodgsonSummarySummary is not available.
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Title: 3D Gravity Inversion Supports the Guyana-Suriname Rifted-Passage Margin of Jurassic Age: But Where Is Its Conjugate?
Authors K. Shipper and P. MannSummaryThe Guyana margin along the northeastern coast of South America represents a 700-km-wide, tectonic transition from a 40–50 km thick and elevated Archean greenstone belt of the Guiana shield and its cover of Precambrian to Paleozoic sediment to normal or thin oceanic crust that underlies the deep Guyana basin of Guyana and Suriname. Suriname is partially fronted by a volcanic margin composed of Middle Jurassic volcanic flows and overlying sedimentary cover that is 25 km thick and underlies the Demerara plateau. Two tectonic models have been proposed for the Mesozoic tectonic origin of the Guyana-Suriname margin: 1) the margin formed as a Jurassic northwest-oriented transform-passive margin during the breakup of North America and northwestern Africa; and 2) the margin formed as a Jurassic rifted-passive margin and was modified by oblique, Aptian opening of the Equatorial Atlantic Ocean. Using GPlates, both tectonic models have been reconstructed to demonstrate a transform-passive margin with northwest extension or an earlier Jurassic rifted-passive margin with initial northeast extension. We perform a 3D gravity inversion of marine satellite gravity constrained by previous marine refraction surveys to investigate both the transform and rift hypotheses for the earlier, Jurassic phase of the Guyana-Suriname margin formation. The inversion reveals the following characteristics supportive of its origin as a rifted-passive margin: 1) margin-perpendicular transects from the 3D volume show that the margin exhibits a necked zone with an average top basement gradient of 4 degrees; there is no evidence for an abrupt truncation and rapid change in crustal thickness that is a defining characteristic of a transform margin; 2) margin-perpendicular transects show crustal thinning beneath the Nickerie rift; and 3) the seaward limit of the Guyana rifted-passive margin is abruptly truncated by the Doldrums fracture zone formed during the Aptian transtensional opening of the Equatorial Atlantic Ocean and as seen in the rifted tectonic reconstruction. This revised interpretation or a Jurassic rifted-passive margin leads to the question of where is its conjugate on the West African margin? We provide a revised plate reconstruction to show a possible early opening rifted-passive margin scenario that was truncated by the later Aptian oblique opening of the Equatorial Atlantic Ocean.
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Volcaniclastics in Cholula-1EXP, Salina del Istmo Basin, Mexico
Authors D. Stanbrook, M. Durcanin, B. LeCompte, C. Farley and N. CapuzzoSummarySummary is not available.
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Tectonostratigraphic Evolution and Thermal Maturity Modeling of the Sergipe-Alagoas Rifted-Passive Margin, Northeastern Brazil
More LessSummaryA grid of 200 line-kms of 2D seismic data, 51 wells, and a compilation of published literature was used to construct a Mesozoic to Recent, tectonostratigraphic framework Sergipe-Alagoas rifted-passive margin of northeastern Brazil. The tectonostratigraphic history of the basin is described according to the structural surfaces and isopach maps of four megasequences bounded by regional unconformities: 1) pre-rift Precambrian crystalline basement and overlying clastic sequence of Early Neocomian age; 2) normal-fault-bounded, clastic syn-rift sequence of Neocomian-Middle Aptian age; 3) post-rift sag clastic sequence of Middle to Late Aptian age; 4) mainly clastic, passive margin sequence of Late Aptian to Recent age. Within the tectonostratigraphic framework, we use the grid of 2D seismic reflection data and wells to identify and map the key elements of the productive petroleum system of the shelf, slope, and deep basin that includes: 1) Cretaceous marine shale source rock of the Riachuelo and Cotinguiba Formation, 2) Known and inferred clastic reservoirs within Upper Cretaceous to Eocene contourites and stacked channel/incised valley associated with the turbidite system fed by voluminous sands of an onshore fluvial-deltaic system, 3) structural traps related to minor faults in the passive margin section and stratigraphic traps related to slope pinch-outs, and; and 4) sealing intervals formed by intercalated hemipelagic marine shale within the Upper Cretaceous to Eocene section. Using these model parameters, we conducted 1D and 3D thermal modeling of two deep wells using lithospheric thickness and heat-flow estimates constrained by the deep crustal structure of the basin described in this study. Model results indicate a 100-km-wide fairway of mature Cretaceous source rocks in the southwestern half of the basin that would have expelled hydrocarbons across the shelf, slope, and deep basin beginning in the Eocene and continuing to the present day. Examples of direct hydrocarbon indicators are shown on seismic lines from this proposed fairway. The largest exploration risk in the northeastern part of the basin is thin or absent source rocks related to Cenozoic seamounts and volcanic plateaus.
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