Abstract
Abstract Marine shelves are a ubiquitous feature of modern Earth, developed across a wide range of scales in many sedimentary basins and representing the flooded portion of basin-margin clinoform topsets. Analysis of 80 clinoforms from 10 basins spanning Cenozoic and Mesozoic icehouse, transitional, and greenhouse climate settings indicates that normalized mean greenhouse marine shelf width is 33% of normalized mean total measured clinoform topset length. The equivalent value for transitional settings is 43%, and 72% for icehouse marine shelves. These values demonstrate that greenhouse marine shelves were substantially narrower than icehouse equivalents, suggesting that narrower shelves with persistent shelf-edge deltas were a consequence of lower rates of accommodation change in greenhouse climate intervals that lacked the large ice sheets required to drive high-amplitude high-frequency glacio-eustasy. Because greenhouse climates have been the dominant mode through Earth history, narrow shelves have probably been the dominant form, and conceptual models based on modern relatively wide shelves may be poor predictors of paleogeography, sediment routing, and sediment partitioning throughout much of Earth history.
Highlights
Marine shelves, the flooded portion of basinmargin clinoform topsets, are ubiquitous physiographic features across modern Earth
Widths of flooded topsets from the 10 basin margin systems range from a 2 km minimum to a 150 km maximum, and when normalized against total clinoform topset length, from 0.09 to 0.94 (Fig. 2)
Analysis of 10 Cenozoic and Mesozoic icehouse, transitional, and greenhouse climate clinoform systems indicates a mean greenhouse marine shelf width of 33% of the mean total estimated clinoform topset length, 43% for transitional strata, and 72% for icehouse strata
Summary
The flooded portion of basinmargin clinoform topsets, are ubiquitous physiographic features across modern Earth. Observations of modern shelf topography are central to many conceptual sedimentological and stratigraphic models (Posamentier et al, 1991; Swift and Thorne, 1992; Galloway and Hobday, 1996; Suter, 2006; Catuneanu et al, 2009). These models influence how researchers observe, interpret, and understand ancient strata and how they reconstruct and predict ancient depositional environments, paleogeography, and climate history.
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