Clinoform geometries and trajectories are widely used to predict the spatial and temporal evolution of sand distribution, but most analytical approaches underplay the significance of topset/shelf processregime in determining how and when sediment is conveyed downdip, or stored on the continental shelf. We present an integrated study of clinoform rollover trajectory and detailed grain-character analysis to assess the role of topset process-regime in determining sand distribution and sediment character across clinothems. This study targets the topset, foreset, and bottomset deposits of four successive Miocene intrashelf clinothem sequences, which represent deposition under either riverdominated or wave-dominated conditions. Seismic reflection data was combined with core analysis and grain-character data derived from 664 samples collected from 3 cored research boreholes. Within river-dominated clinothems, the transfer of coarse-grained sediment occurs under both rising and flatto-falling clinoform rollover trajectories, suggesting that process-regime is more important in determining sediment delivery than clinoform trajectory; river-dominated systems are effective conveyors of sediment into deeper water. Wave-dominated clinothems deposited exclusively under rising clinoform rollover trajectories largely retain sand within topset and foreset deposits; wavedominated systems are effective sediment filters. Notably, deposition under either river-or wavedominated topset/shelf process-regimes results in quantifiable differences in grain-character attributes along clinoform profiles. Sediments in river-dominated systems are coarser, less well-rounded and more poorly sorted, and show greater inter-and intra-sequence variability than those in wavedominated systems; prediction of sediment character is more challenging in river-dominated systems.This study highlights the need for caution when attempting to predict downdip sand distribution from clinoform trajectory alone, and provides a novel perspective into downdip grain-character profiles under end-member topset/shelf process-regime conditions. The results of this study can be used to better-constrain sediment grain-size and grain-shape distributions in process-based forward models, and have widespread applications in prediction of reservoir quality in both frontier and mature hydrocarbon basins. has been largely placed on the balance of accommodation and sediment supply. However, the dominant shelf process-regime also plays a key, but under-acknowledged, role in determining when coarse-grained sediment (i.e., fine sand and coarser) is stored on the continental shelf and when it is conveyed downdip Dixon et al 2012a;Covault and Fildani 2014;Gong et al., 2016;Peng et al., 2017).Recent studies have highlighted that shelf process-regime (resulting from the cumulative effects of fluvial, wave, tidal and oceanographic currents) is an important parameter to consider when predicting the presence or absence of coarse-grained sediment in downdip locations. For example, Dixon et al.(...

Despite a well-documented record of preserved aeolian successions from sedimentary basins characterised by widely variable subsidence rates, the relationship between aeolian architecture and subsidence-driven accommodation generation remains poorly constrained and largely unquantified. Basin subsidence as a control on aeolian sedimentary architecture is examined through analysis of 55 ancient case-studies categorised into settings of ‘slow’ (1–10 m/Myr), ‘moderate’ (10–100 m/Myr) and ‘rapid’ (>100 m/Myr) time-averaged subsidence rates. In rapidly subsiding basins, aeolian successions are thicker and associated with: (1) thicker and more laterally extensive dune-sets with increased foreset preservation; (2) greater proportions of wet-type interdunes and surface stabilization features; (3) more extensive interdune migration surfaces, bounding sets that climb more steeply. In slowly subsiding basins, aeolian successions are thinner, and associated with a greater proportion of (1) aeolian sandsheets; (2) supersurfaces indicative of deflation and bypass. Rapid subsidence promotes: (1) steeper bedform climb, resulting in increased preservation of the original dune foreset deposits; (2) relatively elevated water-tables, leading to sequestration of deposits beneath the erosional-baseline and encouraging development of stabilizing agents; both factors promote long-term preservation. Slow subsidence results in (1) lower angles-of-climb, associated with increased truncation of the original dune forms; (2) greater post-depositional reworking, where sediment is exposed above the erosional-baseline for protracted time. Quantitative analysis of sedimentary stratal architecture in relation to rates of basin subsidence helps demonstrate the mechanisms by which sedimentary successions are accumulated and preserved into the long-term stratigraphic record.Supplementary material:https://doi.org/10.6084/m9.figshare.c.5515695

The continental terrestrial record preserves an archive of how ancient sedimentary systems respond to and record changes in global climate. A database-driven quantitative assessment reveals differences in the preserved sedimentary architectures of siliciclastic eolian systems with broad geographic and stratigraphic distribution that developed under icehouse versus greenhouse climatic conditions. Over 5600 geological entities, including architectural elements, facies, sediment textures, and bounding surfaces, have been analyzed from 34 eolian systems of Paleoproterozoic to Cenozoic ages. Statistical analyses have been performed on the abundance, composition, preserved thickness, and arrangement of different eolian lithofacies, architectural elements, and bounding surfaces. Results demonstrate that preserved sedimentary architectures of icehouse and greenhouse systems differ markedly. Eolian dune, sand sheet, and interdune architectural elements that accumulated under icehouse conditions are significantly thinner relative to their greenhouse counterparts; this is observed across all basin settings, supercontinents, geological ages, and dune field physiographic settings. However, this difference between icehouse and greenhouse eolian systems is exclusively observed for paleolatitudes <30°, which suggests that climate-induced changes in the strength and circulation patterns of trade winds may have partly controlled eolian sand accumulation. These changes acted in combination with variations in water table levels, sand supply, and sand transport, ultimately influencing the nature of long-term sediment preservation. During icehouse episodes, Milankovitch cyclicity resulted in deposits typified by glacial accumulation and interglacial deflation. Greenhouse conditions promoted the accumulation of eolian elements into the geological record due to elevated water tables and biogenic- and chemical-stabilizing agents, which could protect deposits from wind-driven deflation. In the context of a rapidly changing climate, the results presented here can help predict the impact of climate change on Earth surface processes.

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This is a repository copy of Intra clinothem variability in sedimentary texture and process regime recorded down slope profiles.