Testing for eustatic sea-level control in the Precambrian sedimentary record

Abstract

Stratigraphic successions are deposited under the influence of three primary controls, which tend to vary systematically through time. These controls are tectonism (basin subsidence and uplift), sea-level change, and sediment supply. The development of sequence stratigraphy has enabled the introduction of systematic, quantitative methods for the analysis of these controls. The use of the sequence approach requires the establishment of a regional sequence framework and detailed chronostratigraphic control. Working with the Phanerozoic record this approach has revealed a variety of sequence types reflecting long-term tectonostratigraphic processes caused by continental rifting, continental collisions and cratonic dynamic topography, high-frequency thrust-loading cycles in foreland basins, and high-frequency cycles caused by orbital forcing. Glacioeustasy (10 4–5-year periodicity) and eustasy driven by changing rates of sea-floor spreading (10 7–8-year periodicity) have emerged as two significant global processes. Documenting the sequence record in the Precambrian has proved difficult owing to fragmentary preservation and structural deformation. Methods of dating are at present not precise enough to permit reliable regional correlation or testing of high-frequency sequence-generating mechanisms. Some studies of Precambrian sequence architecture have been achieved, but these indicate tectonic processes acting at a much slower rate than during the Phanerozoic. Further analysis of this problem is required.