Petrochemistry and geochronology of Ngorongoro Volcanic Highland Complex (NVHC) and its relationship to Laetoli and Olduvai Gorge, Tanzania

Abstract

OF THE DISSERTATION Petrochemistry and Geochronology of Ngorongoro Volcanic Highland Complex (NVHC) and its relationship to Laetoli and Olduvai Gorge, Tanzania by GODWIN FANUEL MOLLEL Dissertation Director: Professor Carl C. Swisher III The Ngorongoro Volcanic Highland Complex (NVHC) of northern Tanzania is situated at the southern divergence of the Gregory Rift, part of the East African Rift System. The NVHC consists of at least nine major volcanic centers that erupted lavas, ash flows, and other pyroclastic materials from Pliocene to Present. These volcanoes are considered the source of lavas and other volcaniclastic material found interbedded in the adjacent anthropological sites of Olduvai Gorge and Laetoli. This dissertation focuses on the petrochemistry and geochronology of six major NVHC centers: Satiman, Lemagurut, Oldeani, Ngorongoro caldera, Olmoti, and Embagai, as well as Laetoli Ogol lava flows, Olduvai Gorge Bed I lava and the isolated cone of Engelosin. The overall intent is to provide a geochemical and geochronological framework for the NVHC and refine correlations of the NVHC volcanoes with Olduvai and Laetoli. Interpretation of petrographic and x-ray fluorescence data (major element) indicate that the studied volcanoes produced magmas that vary in composition from