The Influence of Basement Structure and Volcanics on the Evolution of the Uruguayan Margin

Abstract

Offshore Uruguay is considered to be an under-explored, potentially prospective region. BG Group has acquired an extensive state-of-the-art 3D seismic survey, which is being studied within the context of an existing multi-client, 2D dataset. The combination of several surveys of both high resolution and long recording times allows the influence of basement structures and volcanics to be determined, within the context of margin evolution. In this study we use 3D imaging of the Rio de la Plata transform zone to enhance our understanding of the interaction between transform faulting and the volcanic processes associated with early margin formation. In particular, we investigate the links between faulting and the spatial development of Seaward Dipping Reflectors (SDRs) within a three-dimensional perspective and use gravity and magnetic data to aid our understanding of the morphology of volcanic features along the margin. Evidence of an incipient spreading centre and raised Moho suggest there has been multiple stages of extension resulting in a complex interplay of strain and volcanism along the transform zone. We provide a number of alternatives to explain the observed features including magmatic contributions from depth in a ‘leaky’ transform system, triggered by oblique south Atlantic opening and the possible existence of an early triple junction. Although the project is primarily focused upon the Uruguayan segment, integration of the conjugate margin of Namibia/South Africa provides a unique insight into the fundamental processes associated with lithospheric extension on both sides of the margin.

AAPG Datapages/Search and Discovery Article #90216 ©2015 AAPG Annual Convention and Exhibition, Denver, CO., May 31 - June 3, 2015