Print this pageAAPG ANNUAL CONFERENCE AND EXHIBITION
Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA
Syn-rift Sedimentology and Stratigraphic Development of Footwall-Sourced Conglomeratic Depositional Systems; South Hadahid Block, Suez Rift, Egypt
(1) Earth Science Department, University of Bergen, Bergen, Norway.
(2) Research Centre, Statoil, Bergen, Norway.
(3) Earth Science & Engineering Department, Imperial College, London, United Kingdom.
Pseudo-3D exposures of Early Miocene conglomerates and sandstones deposited in the immediate hangingwall of the rift-bounding, Sinai Massif Fault allows the syn-rift stratigraphic development of footwall-sourced, transverse depositional systems to be studied. The syn-rift hangingwall succession is also cut by a series of synthetic and antithetic faults and is folded into the Hadahid Monocline to the west and southwest.
The sedimentary succession consists predominantly of coarse-grained conglomerates in close lateral and vertical association with highly bioturbated sandstone facies and mega-breccia units. Close to the rift-bounding fault a basal conglomerates unit is developed. It is 100 m thick and contains breccia horizons, with palaeo-currents directed S to SE, and fines upwards into 100 m of highly-bioturbated sandstones, intercalated with additional conglomeratic intervals. Further to the west the syn-rift succession is dominated by units which coarsen-upwards from highly-bioturbated sandstones into coarse-grained, clast-supported conglomerates, with channel palaeo-currents directed S to SE. These in turn are interbedded with two levels of laterally extensive mega-breccia. This yields a separation between three (100 to 120 m thick) coarsening upward sequences.
The mega-breccia horizons, which are 10-15 m thick, thicken towards the fault, but are consistent in thickness along strike. They consist of a matrix-supported breccia (meter- to decimeter-sized clasts) of pre-rift lithologies. The basal surfaces of the conglomeratic units are more erosive towards the faults with an increase of basement derived clasts towards the top. A decrease in clast size is observed away from the fault (over 1 km distance) and a gradual decrease in dip towards the top of the units and away from the faults (20 to 4 degrees) is seen. Along strike, little variations in thickness, dip and grain size are observed.
By conducting detailed field-based sedimentological and structural analysis, combined with LIDAR technology and oyster dating for better correlation and temporal constraints, we are able to produce a tectonostratigraphic framework which documents spatial variations in thickness and stratigraphic architecture of syn-rift units within the study area.