3D Seismic Data Helps to Lift the Fog - Structural and Stratigraphic Architectural Observations of a Cretaceous Carbonate Platform, offshore Qatar, Submitted to Repeated Emersion and Fluvial Incision

摘要

Arecent marine 3D seismic survey over Block 4, Qatar, provides outstanding images of Mid-Upper Cretaceous stratigraphic intervals and allows detailed observations of both structural and stratigraphic architecture including insights into depositional settings from seismic morphology. The top of theAptian carbonate Shuaiba Formation is a surface of regional significance subjected to exposure and erosion. Seismic data indicates incision by a through going channel system which displays incised valley morphology. From interpretation of multiple seismic derived datasets the stratigraphic architecture of the channel systems is demonstrated and the nature and origin of the channel fill discussed. The structural architecture of Turonian faulting affecting the Shuaiba surface is briefly examined along with the nature of the Turonian Unconformity forming the Middle-Upper Cretaceous Boundary. The Upper Cretaceous succession in Qatar culminates in the deposition of the Maastrichtian Simsima Formation which is capped by a significant unconformity associated with a period of renewed tectonism. Recognising the top Simsima unconformity has proved problematic in the vicinity of Block 4, but detailed seismic interpretation has identified a likely candidate. Moreover, from flattened seismic volumes and Seismic WaveformAnalysis a detailed seismic facies prediction for the Simsima is presented and the affects of syn-depositional faulting on facies distribution highlighted.