--> Abstract: Origin of the Large-Sized Sedimentary Structures in the Upper Eocene Birket Qarun Formation, Wadi El-Hitan (Whale Valley), Fayum- Egypt, by Zaki A. Abdel-Fattah, Murray K. Gingras, and S. George Pemberton; #90078 (2008)

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Origin of the Large-Sized Sedimentary Structures in the Upper Eocene Birket Qarun Formation, Wadi El-Hitan (Whale Valley), Fayum- Egypt

Zaki A. Abdel-Fattah, Murray K. Gingras, and S. George Pemberton
Ichnology Research Group,Department of Earth and Atmospheric Sciences, Alberta University, Edmonton, AB, Canada

Unusual large-sized sedimentary structures are examined from the upper part of the upper Eocene (lower Priabonian) Birket Qarun Formation in Wadi El-Hitan (Whale Valley), SW Fayum Oasis. The distribution of these structures is mappable and the ichnofossils have a characteristic lateral extent along the upper part of the Birket Qarun Formation. The trace fossils are restricted to the flooding surfaces (generally expressed as a transgressive surface of erosion) of the parasequences. The structures are massive-appearing, and of variable size and morphology that varies from between localities. In Sandouk El-Borneta and along Wadi El-Hitan, the ichnofossils have large-diameter (up to dm-scale) branched pillars and/or large horizontal mazes. In the Old Camp section, they are characterized by perpendicular (up to 180 cm height) sub- cylindrical to conical and amphora-like morphology.

The integrated ichnological and sedimentological field data in addition to the examined petrographic thin sections and polished slaps reveal a complex ichnological texture and lithology. The giant biological sedimentary structures are interpreted as indicative of a Thalassinoides ichnofabric belonging to a Glossifungites Ichnofacies. Diagenetic processes are thought to have played an important role in cementing and enveloping of these burrows with concretionary cement (e.g. those of Sandouk El-Borneta). The closely adjacent structures may interpenetrate each other forming a composite conical or subcylinderical structure (e.g. those of Old Camp site). The passive-filling sediments are mostly grayish white sandstones (quartz arenite microfacies) and coquina (rudite microfacies) derived from the overlaying transgressive deposits. The host sediment is represented by the distal bay sediments comprising calcareous sandstones (formainiferal quartz arenite microfacies).

 

AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas