Platform-Margin Trajectory as a Control on Syndepositional Fracture Patterns, Canning Basin, Western Australia

摘要

Syndepositional fractures are an important feature of high-relief, reef-rimmed carbonate systems and exert a profound control on many facets of platform evolution including: the timing and frequency of platform-margin collapse events, generation of an early diagenetic fluid flow system, and subsequent karst and enhanced-permeability development. In the Devonian Reef Complexes of the Canning Basin, syndepositional fracturing increases significantly with progradation, with a twofold increase in fracture intensity observed between the most retrogradational and progradational carbonate platforms. This study demonstrates a statistically significant relationship between syndepositional fracture patterns and variations in stratigraphic architecture, approximated here by platform-margin trajectory. In the platform-margin, syndepositional fracturing varies systematically with platform-margin trajectory, regardless of proximity to regional tectonic elements, whereas in the platform interior, tectonically active settings consistently display syndepositional fracture intensities significantly higher than predicted by platform-margin trajectory alone. The results presented here suggest a first-order relationship between long-term changes in stratigraphic architecture and syndepositional fracture development in high-relief carbonate platforms and imply that whereas external regional tectonic drivers may enhance early fracturing, they are not required.