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Proterozoic to Cambrian Plate-Tectonics and its Control on the Structural Evolution of the Ara Salt-Basin in Oman

Anton Koopman1, Martine Van den Berg2, Karen Romine3, and Previous HitJonTop Teasdale4
1Shell International Exploration and Production, Rijswijk, Netherlands
2Petroleum Development Oman LLC, Muscat, Oman
3FrOG Tech Pty Ltd, Deakin West, Australia
4FrOG Tech Pty Ltd, Norwood, Australia

Reconciling regional plate-tectonic models with the interpretation of structural settings and trap definition is key to understanding the majority of exploration plays. In areas with poor data constraints, integrating plate-tectonics with basic structural geological models is essential.
Over the last two decades conceptual structural models for the Ara salt basin of Oman have alternated between compressive and extensional settings based on limited integration of datasets. The benefits of “regional to local” scale reconciliation is illustrated by a regional framework study on the Late Proterozoic-Cambrian exploration plays of Oman. In this study, gravity, magnetic and seismic data were filtered, interpreted, integrated with all available well data and reviewed within the context of regional-scale plate-tectonic models. This approach has led to a more robust structural model built up from basic Late Proterozoic plate-tectonic components.
Terrane amalgamation followed by a major Nabitah (East African) Orogeny led to the assembly of an East African/Arabian continent and West Gondwana, with additional components associated with a highly right-lateral convergent collision at the periphery of the Malagasy Orogeny to the South. The latter event (also referred to as the “Angudan event” in Oman) culminated with the regional-scale Angudan Unconformity of Early Cambrian age. The partly reactivated remnant Nabitah ranges and the evolving Malagasy Orogeny progressively confined a large marine foreland area, leading to restricted and hyper-saline conditions that resulted in formation of the Ara and Hormuz salt basins. Localised differential relief and areas of increased accommodation space were maintained by largely transpressive deformation along inherited structural trends in the substratum of the evolving sub-basins. Deformation of the intra- and supra-salt depositional units was largely decoupled from the underlying structural trends and was more influenced by salt movement and sediment loading.

 

AAPG Search and Discovery Article #90072 © 2007 AAPG and AAPG European Region Conference, Athens, Greece