Microfacies analysis and paleoenvironmental significance of palustrine carbonates in the Thakkhola-Mustang Graben (Nepal Himalaya)

Discontinuous growth of oncolites and spherical pellets (25-40 μm in diameter) in micritic limestone, algal mats and charophyte algae indicate the presence of both shallow and deep water carbonates. Ostracods in dark micritic carbonates indicate quiet and calm water conditions. Microfabrics of the carbonates suggest that they were deposited in a flat and shallow lacustrine environment. The δ18O values of the investigated limestones of the Thakkhola-Mustang Graben suggest that it attained the current elevation level prior to the east-west extension of the Himalaya.