Degree

Doctor of Philosophy (PhD)

Department

Geology&Geophysics

Document Type

Dissertation

Abstract

The hominin adaptation to East Asia climate and tectonic-climatic interaction are two long-standing research topics but remain elusive. I apply compound-specific isotope analysis of leaf wax n-alkanes to advance the knowledge of these two topics.

Hominins dispersed from Africa to East Asia at ca. 2 Ma. The hominin adaptation to the climate in East Asia remains unconstrained due to the debate in paleoclimate conditions. The Nihewan Basin in North China (40°N) has dense Paleolithic sites, which provides valuable opportunities to study the hominin adaptation. Despite the extensive studies, the paleoclimate records of Paleolithic sites remain incomplete. To reconstruct the paleoclimate, I study the Majuangou Site in the Nihewan Basin, which contains the oldest Paleolithic layer (ca. 1.7 Ma) in North China. While previous studies in younger strata (

Tibetan Plateau is an ideal natural lab to study tectonic-climatic interactions. Numerical modelings suggest that the uplift of Tibetan Plateau leads to the Inner Asia aridification by causing the loss of a nearby water source – the retreat of Paratethys Sea from Central Asia in response to the India-Asia collision – and by blocking moistures due to high elevations. However, another viewpoint attributes the aridification to global cooling, which leads to decreasing atmospheric moistures. I study four sedimentary sections in the Qaidam Basin of northern Tibetan Plateau and reconstructed a composite climate record from ca. 51.3 Ma to 1.7 Ma. My research reveals that global temperature impacts the Inner Asia climate by modulating the latitude of westerlies, the major moisture source, which was located above Inner Asia in icehouse periods and caused wet climate. The retreat of the Paratethys Sea in the Late Eocene and intense uplift of the northern Tibetan Plateau in the Middle Miocene drove aridification. The closure of outlet drainage by the basin bounding Altyn Tagh fault accounts for the lacustrine expansion in this basin during the arid Late Eocene.

Date

1-11-2021

Committee Chair

Zhuang, Guangsheng

Available for download on Wednesday, February 09, 2028

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