Abstract

:Thirty-two limestone facies, four dolomite facies and 10 terrigenous clastics facies show wide variation in a short distance of 600 meters. The limestones represent subtidal (biofacies), tidal channels (oolite facies), bar (oncolite facies), intertidal flats (algal facies), supratidal early diagenetic dolomites and secondary dolomites. Terrigenous clastics were deposited in environments ranging from intertidalsupratidal flats, coastal dunes and subtidal to supratidal flats, coastal dunes and subtidal to supratidal channels. Strontium and Na define the limestone facies and salinity variation. Dolomitizing brines were saline and contained three times more Mn than the depositional solutions. Manganese and Ba in the dolomites indicate mixing of continental and marine brines during dolomitization. Early and late diagenetic chemical imprints are preserved despite prolonged meteoric diagenesis. The carbonate dendrogram depicts four distinct clusters and facies variation related to subtidal, intertidal, supratidal depositional environments, diagenesis and dolomitization. Factor score plots show distinct environmental gradation (from open marine conditions towards the east and restricted marine towards the west) and porosity evolution. Increase of salinity from east to west establishes the continuity of the depositional solutions. Chemical variation of dolomites delineates lateral continuity in the early and late movement of dolomitizing solutions which were generated in the west and moved eastward. The terrigenous clastics dendrogram depicts six distinct clusters corresponding to intertidal-supratidal flats, coastal dunes and subtidal to supratidal channel environments and the diagenetic changes related to silica cementation, dolomitization, iron-coating and mica growth. Factor score plots show gradation of these depositional and diagenetic environments. The type of porosity is fabric selective. The amount of porosity is facies controlled and it is not related to the core recovery.

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