The relationship between the onshore and offshore structure of São Marcos-Quarteira Fault System, Algarve Basin, Portugal.

Abstract

The detailed characterization of the main tectonic structures that can affect basin architecture, segmentation and compartmentalization is paramount in the hydrocarbon exploration of the Algarve Basin. These Characteristics are responsible for structural and stratigraphic trap formation and sedimentary pathways into the offshore. One of the most pragmatic examples in this basin is the São Marcos-Quarteira Fault System (SMQFS).

The SMQFS corresponds to a Hercynian structure that was reactivated during the Mesozoic and Cenozoic under different tectonic regimes, which is still active today. This study pretends to highlight the structural styles associated with the SMQFS and its importance in the Algarve Basin geological evolution, establishing the relationship between its onshore and offshore segments.

In order to understand the SMQFS it is essential to comprehend the complex geological history associated with the evolution of the Algarve Basin and adjacent areas, which still is a challenge. The tectonic history includes the interaction between Western Tethys rifting and the Central and North Atlantic opening and its progress into passive margin, collision between Eurasia (Iberian microplate) and African plate and formation of the Azores-Gibraltar Transform Margin.

The study of SMQFS onshore portion included satellite-derived structural mapping and in situ field observations of the Mesozoic and Cenozoic structure including recent sediments deformation (Plio-Quaternary). In the offshore, 3D seismic interpretation and seismic attribute analysis allowed to recognize the geometry associated to the SMQFS, that when integrated with the historical seismicity record, helped to understand the kinematic relationship between different domains. The characterization of structural style and related accommodation space created by SMQFS movement in the onshore, can build an excellent analogue when extending its behavior into the offshore. Its impact in the region recent seismic activity is also crucial for exploration companies to minimize exploration risk.

AAPG Datapages/Search and Discovery Article #90226 © 2015 European Regional Conference and Exhibition, Lisbon, Portugal, May 18-19, 2015