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Characterization of Sedimentary Basins-Trinidad’s Southern Basin Trinidad’s southern Basin is a topographically low area between the Central Range Uplift and the southern Range Uplift. It forms an eastern part of the eastern Venezuelan Basin, which is positioned east of Venezuela and the Orinoco Delta. The basin is structurally deformed as a result of compressional tectonics. The tectonics are attributed to a triple boundary created from the interplay of the southern American, Caribbean and Atlantic Plates.
Deformation of the Basin is made typical by the Over Thrust Faulting. The Geological formations within the southern basin are marked by sudden and intense folding and deep seated thrust faulting of basement material. These faults are estimated to extend below 35000 ft and exhibit very concave surfaces and gentle deep roots with frequent bifurcations called splay faults. These splay faults extend as far as 10,000 feet below the ground. In order to determine the basin type and the deformation mechanism, the information above has to be analyzed.
It can be deduced, therefore, from the analysis that tectonic loading is the major subsidence mechanism by which basin deformation has occurred. The basin setting shows a convergent nature and can be considered as a Foreland Basin Type. Foreland Basins are basins that lie between the front of a mountain chain and the adjacent craton. Foreland basins in broad terms correspond to the class of perisutural basins on continental lithosphere associated with major compressional zones of deformation which are also known as mega structures.
Foreland basins varies greatly, therefore the exact type of foreland basin that describes the southern Basin the most cannot be decided. Executive Summary A sedimentary basin can be defined as an area where there is a physiographic low or depression in which there is the potential for accretion of sediments transported from a distant source in largely passive margin environment. One of the major sedimentary basins in Trinidad is the Southern Basin. Sedimentary basins tend to be very extensive in areas found in deep water environment where the topography is suitable for accumulation.
Sediments are eroded from the active margins and deposited in inactive or passive margins. These sediments are as a result of extensive and active weathering and are transported large distances by wind water and ice media. Sedimentary Basins are a good structure to preserve representative samples of rock types, minerals, flora and fauna, as well as structural history of the sedimentary rocks which have developed in these areas. The Sothern Basin which was researched in this lab exercise is located between the Central Range and the Southern Range.
The low area of the Southern Basin is positioned between the Central Range Uplift and the southern Range Uplift and forms the eastern part of the Eastern Venezuelan basin, found on the eastern side of Venezuela at the Orinoco Delta. The basin was developed during tertiary times and contains proto Orinoco delta sediments. The southern basin is made up of mainly Miocene and Pliocene to a lesser extent in the quaternary. The southern basin can be described as one of the best producing reservoirs in Trinidad and Tobago due to its structures and litholigies which are both interesting and very valuable. ormationmemberAge(time rock unit)Reservoir rockSource rock Lizard springsnonePaleocenena ciperoUpper cipero-herrera sands. Middle cipero-retrench sands. lower ciperoOligocene-mioceneHerrera sandstonena karamatUpper karamat Lower karamatMioceneKaramat sandsna lenguaUpper lengua Lower lenguaMiocenena cruseUpper cruse Lower cruseMiocene-plioceneCruse sandstoneNaparima hill mudstones forestLower forest clay member. forest member sandsPlioceneForest sandstoneNaparima hill mudstones Morne l’ enferUpper morne l’ enfer sandstone. Lot 7 silt.
Lower morne l’enfer sandstone silt and upper forest clay member. PlioceneMorne l’enfer sandsna morugaCasa cruz sandstine. Las tablas silt. Trinity Hill sandstone. Gros morne Sandstone, silts. St. Hilaire siltsMid MioceneGros Morne sandstoneLower cruse mudstone. mayaroGoudron sand member. Mayaro silt mayaro sandstonePliocene/Miocenena erinporcellanitePlioceneCruse sandstonena gautiernoneCretaceousna cuchenoneLower cretaceousna soldadononePaleocenena Naparima hill noneUpper cretaceousNaparima hill mudstones guayaguayarenonePliocene upper cretaceousna