ABSTRACT: Diagenesis of Diagenetic Quartzarenites, Gebel El-Zeit Area, Gulf of Suez, Egypt
Antar A. Abdel-Wahab, Earle F. McBride
At the northern corner of El Zeit Range, 370 m of sandstone overlie Precambrian granite and underlie Cretaceous marine strata. The sandstones include the marine Lower Cambrian Araba Formation and the overlying dominantly fluvial Upper Cambrian(?) Naqus Formation. The framework composition of both sandstones is almost entirely quartz with trace amounts of muscovite, K-feldspar, and heavy minerals. Up to 18% oversize pores, some filled with younger cements, attest to extensive dissolution loss of detrital grains. Because the final mineralogical maturation of these quartzarenites was through diagenesis, they are diagenetic quartzarenites.
During burial diagenesis, the introduction of 5% quartz cement (unhomogeneously distributed) was followed by locally pore-occluding calcite cement. The sands were then compacted sufficiently to develop slightly sutured quartz grain contacts. These events were followed by extensive dissolution loss of carbonate cement, detrital feldspars, micas, and heavy minerals; by the formation of local patches of kaolinite (average = 6%); and by the formation of extensive iron-oxide cement, including specular hematite. These features suggest extensive invasion of meteoric water and exposure to oxidizing conditions. The time of this event can only be dated as post-Cambrian(?) and pre-Cenomanian. Some outcrop samples contain pore-occluding gypsum cement or mixtures of gypsum and halite cement. Sr
AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990