--> Abstract: Structural Analysis of Sandstone Dykes: Implications for Remobilisation of Deepwater Sand Reservoirs; #90063 (2007)

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Structural Analysis of Sandstone Dykes: Implications for Remobilisation of Deepwater Sand Reservoirs

 

William, Vetel1, Cartwright Joe1, Mario Vigorito2 (1) Cardiff University, Cardiff, United Kingdom (2) Aberdeen University, Aberdeen, United Kingdom

 

We present a structural analysis of sandstone dyke swarms developed with a series of injectite systems in California and France. The sandstone dykes range in aperture from a few centimetres to several meters. These dykes were intruded into mudstones, silty mudstone, and/or diatomaceous mudstones host rocks after burial by several hundred meters. The dykes exhibit many of the classical geometrical relationships seen in igneous dyke systems, including branching, segmentation and/or tip fingering. Our analysis focuses on dyke orientation. We find two end-members: (1) dyke swarms with strongly bimodal strike distributions (e.g. medial-upper portion of the Panoche Hills injection complex, San Joaquin Basin, California) and (2) randomly oriented dyke swarms (e.g. Sisteron, Provence, France). We interpret the bimodal end member to be representative of remobilisation and intrusion during a phase of active tectonism, in which horizontal stresses were strongly aligned in the prevailing tectonic stress regime. We interpret the randomly oriented end member to have formed in a passive tectonic setting, in which horizontal stress was isotropic. These preliminary models for the occurrence of sandstone dyke swarms are the first step in an attempt to develop predictive models to allow sandstone intrusions to be built into reservoir models. They also have considerable implications for reconstruction of in situ stress regimes in petroliferous basins.

 

AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California