Paleocene and Lower Eocene shallow-water limestones of Tibet: Microfacies analysis and correlation of the eastern Neo-Tethyan Ocean

Microfacial investigations of the Lower Paleogene sediments were based on four sections of the passive Indian (Ladakh, Tingri County, Gamba County and Yadong County) and one of the active Asian continental margin (Zhongba County). Eleven microfacies from the Tethyan Himalaya (prefixed with P for passive continental margin) and four from the Xigaze forearc basin (prefixed with A for active continental margin) were observed. The distribution of fossil assemblages in the environment ranges from the tidal flat and restricted lagoonal part of the inner carbonate ramp to the outer carbonate ramp: (P1) green algae pack-/grainstone with small miliolids, (P2) bioclast grainstone, (P3) Rotaliidae packstone, (P4) Miscellaneidae-Rotaliidae-Nummulitidae pack-/grainstone, (P5) laminated and bioturbated mud- and grainstone, (P6) Alveolina wacke-/packstone with Soritidae, (P7) Nummulites-Alveolina-Orbitolites pack-/floatstone, (P8) Discocyclinidae-Nummulitidae pack-/floatstone, (P9) Rhodolith wacke-/packstone, (P10) mudstone with anhydrite nodules, (P11) planktonic foraminiferal wackestone, (A1) molluskan float-/rudstone, (A2) Nummulitidae wacke-/packstone, (A3) rhodolith wacke-/packstone, (A4) Discocyclinidae-Nummulitidae float-/rudstone. The correlation of our observations provides a detailed overview of the paleoenvironmental development and the sedimentary history of the eastern Neo-Tethyan Ocean, showing a deepening trend in two stages from Lower Paleocene to Lower Eocene.