STRATIGRAPHIC DISTRIBUTION OF THE LARGER BENTHIC FORAMINIFERALOCKHARTIAIN SOUTH TIBET (CHINA)

Abstract

This paper reveals the stratigraphic applicability of the larger benthic foraminifer (LBF) Lockhartia from the Paleocene to Lower Eocene of the eastern Neo-Tethyan Ocean outcropping in South Tibet. During the Paleocene, faunas of the western and eastern Neo-Tethys show distinct differences: The western area is dominated by coralgal assemblages, while in the east, LBF predominate the so-called “ Lockhartia Sea”. Shallow-water limestones of Tingri, Gamba and a completely new section close to the village of Guru in the eastern Neo-Tethyan Ocean reveal the stratigraphic ranges of seven species of Lockhartia : L. conditi, L. haimei, L. hunti, L. praehaimei, L. retiata, L. roeae and L. tipperi . Five interval biozones, called “ Lockhartia biozones”, are defined for the Paleocene to Lower Eocene based on the stratigraphic distribution of these species. The biozones are used to facilitate regional correlations of the three sections and to compare them with the well-established shallow benthic zones (SBZ) used for biostratigraphy of shallow-water environments. The stratigraphic distribution of Lockhartia suggests an earlier evolution of some species in the eastern Neo-Tethyan Ocean compared to the western region as a result of different latitudinal positions of the ocean basins.