Opportunities for Interdisciplinary Studies in Sedimentary Basins: an Introduction to the Hedberg Conference on Structural Diagenesis

Stephen E. Laubach¹ and Kitty L. Milliken^2
1Bureau of Economic Geology, Austin, Texas
²Dept. of Geology, University of Texas, Austin, Texas

        This conference is devoted to the idea that examining links between mechanical and chemical processes in sedimentary basins can transform our scientific knowledge about a part of the Earth’s interior that is of great intrinsic and practical interest. Owing, perhaps, to decades of petroleum industry focus on shallow parts of sedimentary basins, where original depositional fabrics may dominate petrophysical properties, artificial boundaries have arisen between the disciplines of rock mechanics, stratigraphy, sedimentary geochemistry, sedimentary and structural petrology, structural geology, and geophysics. Current efforts at drilling into deeper and less conventional exploration targets requires breaking these disciplinary boundaries in order to exploit new analytical techniques and instruments, laboratory tests, and mechanical and diagenetic models that can advance our understanding of porosity evolution in diagenetically-altered, fractured, and faulted rocks. New data and concepts that arise from such a holistic approach can be crystallized into predictive models for geological attributes where samples are sparse or nonexistent. A likely benefit of a cross-disciplinary program focused on fundamental processes by which rock properties evolve will be a better conceptual framework for accessing future energy supplies and for devising the means to extract these resources.
        Despite temperatures that are elevated relative to those at the surface, reactions in deep basin settings are still dominated by kinetics, and rocks therefore preserve a complex history of their modifications. In such systems, prediction of reaction paths and mechanical behavior cannot be derived from an understanding of bulk composition and thermal conditions alone and a comprehensive assessment of both chemical and mechanical aspects of rock history is essential. There is an ever-growing body of evidence that, across a spectrum ranging from grain fracture in early compaction to mineral precipitation in tectonically-produced veins, to mineral coatings on rock joints formed during uplift, chemical and deformational histories can be deciphered in concert to reveal links that appear to be genetic. This conference brings together a spectrum of expertise that can address the goal of describing and predicting the behavior of this complex, interesting, and important system.

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