The impact of shelf margin geometry and tectonics on shelf-to-sink sediment dynamics and resultant basin fill architectures



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This dissertation focuses on understanding the relative importance of external (eustacy) versus local tectonic and sedimentary processes in controlling continental-margin depositional architectures and their implications for sediment distribution. The emphasis of this study is the interpretation of clinoform geometries and stratigraphic relationships observed on 3D and 2D seismic reflection data in the Taranaki Basin, which is characterized by a variety of clinoform architectures on its Pliocene-Recent margin (Giant Foresets Formation). I combined seismic stratigraphic interpretations and biostratigraphic studies using a dataset that consists of 1,700 km2 of 3D seismic lines, 4,000 km of 2D regional seismic lines, and data from six wells. The study was divided into three sections. First, three major stages of clinoform evolution were identified based on their architectural and geomorphological characteristics. Isochron maps were generated to identify correlations between stratigraphy and paleostructures, and seismic attribute maps were elaborated to identify and characterize geological features and depositional elements. In the second phase of the study, 2D stratigraphic forward modeling techniques were applied in an effort to quantitatively determine the relative importance of the mechanisms acting in the basin (eustacy, tectonism and sediment supply). Finally, a similar approach was applied using clinoform morphologies in the eastern Trinidad margin where the tectonic configuration of the basin was completely different to the one in the Taranaki Basin. The objective was to compare the results in a region with different a tectonic setting to validate the applicability of the methodology in other basins worldwide. The results of this research indicate that the methodology that was developed for the quantitative analysis of clinoform architectures in the Taranaki Basin is applicable to other basins worldwide and that the work flow provides a more comprehensive understanding of the factors that influence continental margin development. Generic observations of this research showed that (1) underlying structures in the shelf and slope area can play an important role in influencing the location and morphology of the shelf edge area and controlling sediment distribution; (2) high sediment supply, along with accommodation, play a key role in the construction of high-relief clinoforms and earlier dispersal of sediments into deep water; and (3) lateral variations associated with high sediment discharge sources (e.g. paleo Orinoco shelf-edge delta) can generate important changes in continental-scale clinoform architectures alongstrike in continental margins influence sediment distribution patterns in the deep-water component of the basin.