Geological Society of London
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Late Cretaceous–Cenozoic sediment and turbidite reservoir supply to South Atlantic margins

posted on 2016-06-21, 11:05 authored by Duncan S. Macgregor

Maps have been compiled of indicators of uplift, denudation, sedimentation rates, igneous activity and climate over South Atlantic margins in order to develop the most consistent interpretation of the development of topography, climate and sediment supply through time. Continental margin uplifts and associated topography are concentrated in the Late Cretaceous and Oligocene–Recent periods, with the rates of sediment supply from these dependent on the occurrence of wet or rapidly changing climate. An irregular bimodality is seen on several aspects of African and Brazilian margin geology through time, particularly on periods of sediment progradation, high sedimentation rates and turbidite reservoir development, with peaks of "each centred on the Santonian and Miocene. Some regions show only one of these sedimentation rate peaks and the bimodal pattern, in general, is weaker for the Brazil margin, attributed to continuing uplift of southern Brazilian margins in the early Palaeogene.

A crude relationship is observed between sedimentation rate and reserves in turbidite reservoirs. Sedimentary rate mapping can thus be used to identify turbidite fairways of different ages, tied in turn to drainage catchments containing a combination of high topography and wet climate. Additional implications for source rock development and burial history are also explored.