Shelf-prism clinoforms in the pre-vegetation world

Early Silurian Shelf-Prism Clinoforms Progradation and Implications for Pre-vegetation Sedimentary Source to Sink Systems, a Case Study from Central Arabia

Research into this project has been holistic and multi-scale, I focused on all segments of the depositional system: catchment, shelf, slope and basin (with more emphasis on the latter two)

Introduction

A Early Silurian sag basin is revealed by integration of sedimentological, biostratigraphic, borehole wireline logs and seismic analysis over Central Arabia. This intracratonic basin is filled with deep-marine, slope, shelf and fluvial deposits, representing a complete basin fill cycle during a long-term post-glacial highstand systems tract, with intermittent high-order transgression-regression cycles. Slope and basin floor sands are in close proximity temporally and spatially to an organic-rich source rock in central Arabia and so could be potential hydrocarbon reservoirs. Recent 3D seismic data shows large clinoforms downlapping on the base Silurian. These 700-metre-high clinoforms could help identify slope-to-basin reservoir sands. Detailed seismic mapping and integration with borehole geologic data as well as additional stratigraphic and regional analysis are essential to further our understanding of the Early Silurian deep-marine depositional system. This study is also significant because it is the only documented case (as of 2018) of large-scale clinoforms from the pre-vegetation world when the absence of land plants enhanced the fine-grained portion of the sediment budget bypassed to the shelf.

Objectives:

  • Evaluate Early Silurian (Rhuddanian) clinoforms and associated geomorphologies imaged on 3D seismic in detail using conventional seismic interpretation techniques as well as advanced seismic attribute methods.
  • Convert seismic interpretation to depth as well as backstrip/decompact the Rhuddanian succession in order to appreciate the clinoforms size and compare them to other younger successions of the same scale, not just the size but progradation and sedimentation rates as well.
  • Integrate borehole data (sedimentological, biostratigraphic, wireline logs) to subdivide the Rhuddanian succession into basin floor, slope, and shelf/deltaic broad segments. Also, use this data together with literature to constrain the Rhuddanian basin size.
  • Study sediment provenance for this succession and determine the size of drainage, the availability of which allows for a source-to-sink statistical analysis and an indirect way to quantify Rhuddanian basin floor fans in central Arabia.
  • Analyse deep water slope channels within the clinoforms and determine their fill and if rapid slope progradation and/or absence of land plants on the coeval alluvial plain had an effect in their evolution. Also, determine if their evolution had adverse effects on basin floor fan size/thickness.
  • Evaluate delta transit times (delta-scale clinoform progradation) of modern systems and calculate their Rhuddanian counterparts.
  • Study the hyperpycnite facies that are persistent throughout the Early Silurian succession of central Arabia, investigate favourable hyperpycnal conditions in modern rivers, and the implications of hyperpycnal rivers on pre-vegetation fluvial landscapes.
  • Examine the effects of paleoclimate on this depositional system through climate simulation of the Early Silurian (with help from Atmospheric group in Manchester)
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