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Full-Text Articles in Physical Sciences and Mathematics
Non-Mass Dependent Isotope Fractionation: An Application In The Hyperarid Environment And A Set Of Experiments On Thermal Diffusion, Tao Sun
LSU Doctoral Dissertations
This dissertation consists of two independent topics; both are related to non-mass dependent isotope fractionation. 1) Atacama Gravel Sulfate: The onset of hyperaridity of Atacama Desert is of geological importance and has been controversial. I put constraints this timing by looking into a new record, a deep sulfate profile extending from the surface down to the oxide zone of a copper ore in the Atacama Gravels, whose deposition covers a majority of the Central Depression and temporarily spans from semi-arid to hyper-arid climate. The gravel sulfates show a strong depth-dependent pattern through ~50 meters (15 to 65 meter depth): narrow …
Stories Of The Proterozoic Earth: Paleoproterozoic Chuanlinggou Arcitarchs And Neoproterozoic ¹⁷O-Depleted Barite, Yongbo Peng
Stories Of The Proterozoic Earth: Paleoproterozoic Chuanlinggou Arcitarchs And Neoproterozoic ¹⁷O-Depleted Barite, Yongbo Peng
LSU Doctoral Dissertations
This dissertation consists of two independent topics, both critical to understanding Earth history during the Proterozoic Eon. (1) Paleoproterozoic Chuanlinggou Acritarchs: The eukaryotic affinity of acritarchs from the Chuanlinggou Formation has been questioned because of lack of indisputable morphological evidence. In this study, Chuanlinggou acritarchs were examined by jointly using optical microscopy, scanning electron microscopy, and transmission electron microscopy. In most cases, an ovoidal group of acritarchs represents a half-vesicle following a complete longitudinal rupture, which is a morphological model different from a whole envelope with medial splits, as proposed by earlier studies. This ovoidal group displays a bipolar morphology, …