الفهرس 
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Abstract
The present work deals with microfacies analysis, mineralogy and chemistry of the Middle Miocene Marmarica Formation exposed at Matruh area. The main objectives include the recognition of the major sedimentary environments as well as the main diagenetic processes. The petrographic investigation leads to the recognition of five carbonate microfacies. Only two clastic rich units were recognized; constitute about 6% of the measured sections; differentiated into glauconitic calcareous sandstone and fossiliferous calcareous quartz wacke. The carbonate microfacies are represented by: floatstone/wackestone (74.7%), wackestones (13%), packstone (6.5%), rudstone/packstone (3.6%) and grainstone (2.1%). The recorded fauna suggest a fully marine environment within the photic zone. According to the zoarial growth of the bryozoa, the bottom of the Mamarica sea was not deep (15 – 45 m optimum depth) and the climate was moderate to warm. A depositional model for the carbonates of the Marmarica Formation in Matruh area has been constructed by combining environmental interpretations of carbonate facies and associated biogenic components. The Middle Miocene carbonates of Marmarica Formation possess features that indicate the deposition on a carbonate ramp. The post Middle Miocene sediments are represented by the Plio-Pleistocene Pink Limestone and the overlying calcretes. A range of diagenetic features are observed in Marmarica Formation: micritization, cementation, leaching, cavity filling, neomorphism and dolomitization. A rapid increase in bryozoan abundance is informally termed ”bryozoan event”. This Middle Miocene ”bryozoan event” was accompanied with numerous skeletal remains of other group of organisms.