Environmental and tectonic controls on the evolution of Devonian reef complexes

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Modern coral reefs, such as the Great Barrier Reef off the Australian coast, are sensitive indicators of environmental change.  Similar reefs also flourished during other times in the Earth's past history, and these now fossilized reefs provide a valuable record of ancient marine environments.  Reef limestones and dolostones are also of economic interest as hosts for mineral deposits and as petroleum reservoirs.  Reefs of Devonian age (380-360 million years old) are well preserved in western Canada and northwestern Australia.  These Devonian reefs provide a record of a critical time in the Earth's history when the Pangea supercontinent was being assembled, global greenhouse and icehouse climates prevailed, and global extinction of marine organisms occurred.  The primary objective of my research is to reconstruct the history of Devonian reef evolution in western Canada and northwestern Australia by means of a multi-disciplinary study of the reef platform successions.  This objective will be achieved by (1) detailed examination of platform deposits and patterns of sedimentation; (2) determining the depositional ages of the platforms using fossil and geochemical indicators; (3) correlating deposits between platforms and from platform-to-basin; (3) documenting ancient soil horizons and karst formed in exposed reefs; (4) examining organic-rich rocks, which will provide information about nutrient levels; and (5) characterizing the changes across the mass extinction events recorded in the Devonian reefs.  Observations and rock samples will be collected from selected outcrops, quarries and drill-cores in western Canada and northwestern Australia, and integrated with geophysical and microscopy data and chemical analyses.  This integrated approach will allow us to elucidate the complex interplay of sea-level fluctuations, movements of the earth's crust, sedimentation processes and post-depositional alteration that have controlled the architecture and evolution of the Devonian reefs.  This research ultimately has important implications for understanding the nature of reefs through time, for predicting the behaviour of modern reefs and for assessing the impact of human activity on these sensitive ecosystems.