Cambrian series 3 trilobite biostratigraphy and geochemical studies of the kunzam la parahio formation Sumna Kilung Valley Spiti Himalaya

Abstract

The thesis incorporates Cambrian Series 3 (now named Miaolingian) trilobite biostratigraphy and geochemical studies of the Kunzam La (Parahio) Formation, Sumna (Kilung) Valley, Spiti, Tethyan Himalaya. This work recognises Cambrian Series 3 (Miaolingian) trilobite levels and biozones and geochemical studies (REE and trace elemental studies) in the Sumna Valley. In total ~470 m of the Kunzam La (Parahio) Formation yielded trilobite faunal elements of Oryctocephalus indicus biozone (~509 Ma), Paramecephalus defossus biozone (~506 Ma), Oryctocephalus salteri biozone (~505 Ma), Xingrenaspis-Pagetia level (~504 Ma), and Iranoleesia butes level (~503 Ma) and provide an age within the Wuliuan (Miaolingian). Biostratigraphic correlation and comparative studies of the biozones from the Sumna Valley and the Parahio Valley has been established. The REE and trace elemental analysis is interpreted in terms of depositional setting, provenance and the tectonic setting and analysis indicate that the sediments of the Sumna Valley were deposited in oxidising environment in a passive margin tectonic setting with proximal, near-shore environment and point to larger continental detrital deposits, thereby, suggesting a proximal rather than a distal location of the basin. Sediments of the Kunzam La (Parahio) Formation were derived from the uniform source area of felsic composition which possibly lies in the old Precambrian Indian craton. A major transgressive (maximum flooding surface) event has been recognised at the beginning of the O. indicus biozone. newline