Some aspects of depositional and petrographic frameworks of carbonate rocks of the late Neoproterozoic Krol Group, Lesser Himalaya, India

摘要

Late Neoproterozoic carbonate deposits are well documented from the Krol Belt, Lesser Himalaya. The Krol A and Krol B Formations of the Krol Group are characterized primarily by a succession of micritic limestone/ marl and red/green shales, respectively. In contrast, the Krol C and D Formations are characterized by thick sequences of limestone and dolomite showing deep subtidal to supratidal/ karstic depositional features. Petrographic textures recorded in Krol C and D carbonate rocks include fenestral void filling/ fascicular optic type fibrous dolomites; dedolomitisation features, cloudy center clear rim dolomite (CCCR texture), Baroque dolomite, chert-dolomite association, oolites, cementation of algal mat fragments and anastomosing microstylolitic (nonsutured) seam solution. Both early and burial diagenetic textures are observed in these carbonate rocks. The petrographic studies may help to understand the diagenetic evolution Krol carbonates, including early and burial dolomitization pathways.