Tectonic Mechanisms

Abstract

Sea-level changes within a basin may be caused by movements of the basement rather than changes in global sea level (eustasy). In Chap. 9 we examine long-term mechanisms of basement movement driven by deep-seated thermal processes, including the generation of dynamic topography, and we also discuss eustatic sea-level changes driven by changes in ocean-basin volume. These processes act over time periods of tens to hundreds of millions of years and are continental to global in scope. In this chapter, we discuss relative sea-level changes caused by continental tectonism that are regional to local in scope, and act over time periods of tens of millions to tens of thousands of years (possibly less). Tectonism of this type is driven primarily by crustal responses to plate-tectonic processes. Extensional and contractional movements accompanying the relative motions of plates cause crustal thinning and thickening and changes in regional thermal regimes, and this leads to regional uplift and subsidence. These stresses and strains are generated primarily at plate margins but, because of the rigidity of plates, they may be transmitted into plate interiors and affect entire continents.