Mass transport complexes form a significant component of the stratigraphic fill in ancient and modern deep-water basins worldwide. One such basin, the deep marine margin of eastern offshore Trinidad, situated along the obliquely converging boundary of the Caribbean and South American plates and proximal to the mouth of the Orinoco River, is characterized by catastrophic shelf margin processes, intrusive and extrusive mobile shales, active tectonics and prolific migration and sequestration of hydrocarbons. Major structural elements that characterize the deep-water slope regions of this area include:

• large transpression fault zones (i.e., Darien Ridge, Central Range, Los Bajos) along which mobile shale walls are extruded,
• fault-cored anticlinal structures overlain by extrusive seafloor mud volcanoes,
• shallow-rooted sediment bypass grabens near the shelf break, and
• normal regional and counter-regional faults.

A mega-merged, 10,000-sq. km. 3D seismic survey reveals several erosional surfaces that form the boundaries of enormous mass transport complexes (MTCs). The data shows numerous episodes of MTC development, characterized by chaotic, mounded seismic facies and fan-like geometry. Their extent (6700 sq. km) and thicknesses (up to 250 m) are strongly influenced by seafloor topography. These systems show run-out distances from the source area of 60 to 100 km. Depositional architecture identified with these units include huge lateral erosional edges, linear basal scours and side-wall failures. Mud volcanoes buffer deposition and produce sediment shadows on their downdip side; these depositional remnants are potential stratigraphic traps.MTCs are believed to be produced by failures initiated by sediment accumulation and oversteepening of the slope, tectonic movement, high-frequency sea level fluctuations and/or possibly hydrate destabilization and dissolution.

Several architectural elements documented in the MTCs in offshore Trinidad have been identified and described in similar settings around the world. Basal scours are common in MTCs located in the continental margins of offshore Brunei, offshore eastern Borneo (Indonesia) and the Monterey channel-mouth lobe in offshore California. Side-wall failures or syndepositional faults have been described in outcrop studies in the Jackfork Formation, Ouachita Mountains, of Arkansas. Equivalent “imbricate slices” have also been reproduced in laboratory gravity transport experiments. All these well-documented case studies are used as potential analogs in the deep marine settings of offshore Trinidad. The objective of this research is to better understand the role that MTCs play in forming continental margins around the world and the effect that they have on fluid flow and reservoir development within deep water basins.

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