SEDIMENTARY BASIN INVERSION AND INTRA-PLATE SHORTENING

Abstract

Sedimentary basin inversion, the shortening of formerly extensional basins, is accommodated mainly by compressional reactivation of extant faults and fractures across a wide range of scales. As such, inversion is a large-scale manifestation of Byerlee friction, the dynamic criterion for fault reactivation governing the effective shear strength of the shallow crust. Basin inversion generates distinctive deformational architecture, and it is implicated strongly in sedimentary basin exhumation. As a principal source of horizontal stress, inversion drives significant sedimentary porosity reduction and resultant fluid flow. Upper crustal deformation is critically dependent on fluid overpressure (i.e., pore fluid pressures greater than would be calculated from a hydrostatic gradient), and, perhaps more than in any other tectonic setting, overpressures are potentially large during sedimentary basin inversion. This review therefore includes discussion of the role of fluid overpressure in inversion and the evidence for it. Collectively, inversion has profound implications—good and bad—for the prospectivity of many petroliferous sedimentary basins. Thus, recognizing the evidence for basin inversion, quantifying its magnitude and understanding the mechanisms that accommodate inversion and other phenomena affected by it, have become essential components of the basin analyst's remit.