Keywords and Phrases
Cracks; Diagenesis; Lacustrine; Redox conditions; Shale
“This study aims to decipher provenance, redox conditions, and burial history of shales in Chang 7 Member of Upper Triassic Yanchang Formation, Ordos Basin, China. The first paper discusses the origins of single-channeled, vertical, sinuous, and calcite-bitumen-filled cracks in the shales. Results show that in early diagenesis, unconsolidated mud was expanded open by escaping gases produced during organic matter maturation under hydrothermal influences. Calcite initially filled the cracks; bitumen and pyrite came in later and occupied the cracks in various ways. Compaction occurred next and folded the calcite- and bitumen-filled cracks into sinuous shapes. The second paper uses geochemical and petrographic features to solve the conflicting redox conditions of Chang 7 shales reported in previous studies. Results show complete oxic-suboxic conditions in sections and wells on the north, while dominantly anoxic in sections on the south. Conflicting redox conditions of Chang 7 shales discovered both in this study and previous studies are caused by limited extent of anoxic water body. The maximum lateral extent of anoxic water body is outlined roughly parallel to the 10 m isopach line of high-GR shale in Chang 7. The third paper examines mineral compositions of shales determined by XRD analysis to identify its provenance. Results show multiple provenances and reveal that the quartz-albite correlation is a useful provenance indicator. This study provides a detailed reconstruction of provenance, redox conditions, and burial history of a lacustrine shale and improves our understandings on origin of the shale”--Abstract, page iv.
Borrok, David M.
Wronkiewicz, David J.
Geosciences and Geological and Petroleum Engineering
Ph. D. in Geology and Geophysics
Missouri University of Science and Technology
Journal article titles appearing in thesis/dissertation
- Calcite and bitumen-filled cracks in an Upper Triassic lacustrine shale: A mesozoic molar-tooth structure originated from hydrothermal events
- Reconstruction of redox conditions and the maximum lateral extent of anoxia during deposition of shales in Chang 7 member of Upper Triassic Yanchang Formation, Ordos Basin, China
- Quartz-albite correlation as a shale provenance indicator, Upper Triassic Chang 7 shale of Yanchang Formation, Ordos Basin, China
xiv, 135 pages
© 2019 Bin Sun, All rights reserved.
Dissertation - Open Access
Sun, Bin, "Provenance, redox conditions, and diagenesis of shales in Chang 7 member of Upper Triassic Yanchang Formation, Ordos Basin, China" (2019). Doctoral Dissertations. 3139.