PROGRESSIVE DIAGENETIC SEQUENCE OF PLEISTOCENE CORAL REEFS IN THE AREA BETWEEN QUSEIR AND MERSA ALAM, RED SEA COAST, EGYPT

Journal Article

• المجلة \ الصحيفة: Egypt J Geol.
• رقم العدد: 1
• رقم الإصدار السنوي: 41
• الصفحات: 519-540

مستخلص المنشور

Pleistocene coral reefs along the Red Sea coast occur in three
stratigraphically different units. Theyform terraces of different elevations
above the present sea level and are characterized byfringing reef types,
comparable to their recent counterparts. The three reef units show a
progressive diagenetic sequence. The lower unit (youngest) is characterized
by almost unaltered primary microstructure. Meteoric leaching in only
documented is the form of open trabecular centers of coral skeletons.
Marine micritic linings of aragonitic biota arefrequent features. marine
cements of aragonite and high-magnesium calcite (HMC) are wellpreserved.
The middle unit is characterized by an increased leaching of the
trabecular centers. Low magnesium calcite (LMe) started to prcipitate,
while aragonitic biota show an intense leaching. They are frequently
recorded as molds with meteoric lining. The upper unit (oldest) is
characterized by complete loss of any primary microstructure, a continuous
reduction of biota from the fossil record, an increase in meteoric LMC
cements and a decrease inporosity. A number of stable isotope datafrom
selected coral species underline these changes.