oa Distribution of Carbonate Cements within Depositional Facies and Sequence Stratigraphic Framework of Shoreface and Deltaic Sandstones: Evidence from Lower Miocene Succession, the Gulf of Suez Rift, Egypt

The shoreface-offshore (transgressive systems tract TST and highstand systems tract HST) and coarse<br>-grained deltaic (lowstand systems tract LST) calcarenite and hybrid arenites of the Mheiherrat<br>Member of the Rudeis Formation, Early Miocene, the Gulf of Suez, Egypt were pervasively cemented by<br>carbonate cements and less amounts of zeolite, palygorskite, pyrite and iron oxides. The spatial and<br>temporal distribution of carbonate cements were constrained within a sequence stratigraphic<br>framework. The shoreface-offshore TST and HST calcarenite and hybrid arenites, particularly below<br>parasequence boundaries (BP’s), transgressive surface (TS) and maximum flooding surface (MFS) were<br>pervasively cemented by (i) grain-coating and inter- and intragranular pore-filling microcrystalline<br>calcite (e.g. circumgranular isopacheous acicular, and columnar and small amounts of circumgranular<br>equant) and inter- and intragranular pore-filling coarse-crystalline calcite (e.g. poikilotopic and<br>overgrowths) with δ18OVPDB = -3.6 to -0.3 ‰ and δ13CVPDB = -2.3 to -0.7 ‰, and (ii) non-ferroan<br>rhombic dolomite (δ18OVPDB = -3.9 to +0.9‰; δ13CVPDB = -2.5 ‰ to -0.7 ‰). The coarsegrained<br>deltaic LST calcarenite and hybrid arenites was pervasively cemented by (iv) grain-coating<br>calcite (e.g. columnar and circumgranular equant) and inter- and intragranular pore-filling coarsecrystalline<br>calcite (e.g. poikilotopic and overgrowths) with δ18OVPDB = -4.4 to -2.3 ‰; δ13CVPDB = -<br>2.8 to -1.3 ‰, and (v) small amounts of non-ferroan rhombic dolomite (δ18OVPDB = -4.8 to -2.5 ‰;<br>δ13CVPDB = -3.3 to -1.5 ‰). Such extensive cementations by carbonates i.e. calcite and dolomite<br>particularly below BP’s, TS and MFS were being facilitated by the presence of detrital carbonates and<br>bioclasts. This study demonstrates that the spatial and temporal distribution of diagenetic alterations in<br>deltaic and shallow marine calcarenite to hybrid arenites can be better predicted when linked to<br>depositional facies and sequence stratigraphy.