Present day

A PRESENT DAY ANALOG OF CONTINENTAL TO ULTRA DEEP SAND DEPOSITION: THE ORINOCO-AMAZON SYSTEM (NE CORNER OF SOUTH AMERICA).
Abstract by Jesús López

Based on uniformitarianism concept, the currenttectonical, morphological and sedimentological condition present in the Orinoco –Amazon system, lead to a better understanding and comprehension not only of the evolution of any basin located inactive margin, but also the intrinsic analogy between sedimentary environments on the ground surface and the sea floor. Three main features –Tectonic, climate and Global water circulation - control thedeposition of sediments, at different stage and scale, since the Andes to the sea floor. Through this detailed study, we can see how the tectonic, the more important feature, is controlling themorphology of both ground surface and the sea floor, not only at regional scale (active margin, transcurret margin, mountain belts,etc) but also at local one (rivers controlled by fault). The morphology, atthe same time, provides conditions for the sediments at the time of the deposition (controlling the curse of rivers and sea channel in large scale; and variation in the shape of the sea surfaceproviding folds and basin in a small scale). Two example seen in this study, show the intrinsic tectonicmorphology-sediments relationship. The Andes, which represents a topography effect that is controlled bytectonic, provides 90% of the sediments deposited in the Orinoco delta and; some fault on sea floor create escarpments and subsequently trench which control all the debris flow giving place downwardto turbiditic deposits. Other important control feature that has a direct influence in sedimentation, at different scale, is the climate. The change between hot and cold water creates, for longperiods, changes on the sea level. During hot periods, in highstand, the mouth of the Amazon River is located on the shelf, where the load sediments can be distributed on this. Otherwise, during cold...