Classification of basins, with special reference to Proterozoic examples.

Abstract

Basin classification rests on a plate tectonic foundation, highlighting lithospheric substrate, proximity to plate margin and relative motion of the nearest plate boundary. Major mechanisms for regional subsidence and uplift are subdivided into isostatic, flexural and dynamic groups. Basin-forming mechanisms and basin types do not exhibit simple cause-and-effect relationships, but rather reflect a matrix-type relationship. Different basin types have different spans of existence, with generally shorter life spans related to more tectonically active settings. Many ‘polyhistory’ basins, composed of two or more megasequences, reflect a long evolution dominated by different basin-forming and basin-modifying mechanisms. The supercontinent cycle is marked by distinct sets of basin types, developed during successive phases of the cycle. Major classification schemes are reviewed briefly, before surveying the range of basin types represented in the Proterozoic of several key cratonic areas. Basins examined encompass almost the entire Neoarchaean–Neoproterozoic period. All of these basins have a relatively long history of preservation, which can be tied to the essentially continental character of their basement rocks and concomitant enhanced ‘survivability’. Their preservation thus underlines the longevity and inherent stability of the continental lithosphere. The distinction between basin occurrence over geological time and preferential preservation is important when viewing the geological record.