Palaeoceanographic controls on geochemical characteristics of organic-rich Exshaw mudrocks: role of enhanced primary production |
| |
| Institution: | 1. Key Laboratory of Orogenic Belts and Crustal Evolution, School of Earth and Space Sciences, Peking University, Beijing 100871, China;2. State Key Laboratory of Biogeology and Environmental Geology, School of Earth Sciences, China University of Geosciences, Wuhan 430074, China;3. Key Laboratory of Petroleum Resources Research, Institute of Geology and Geophysics, Chinese Academy of Sciences, #19 Beitucheng Xilu, Chaoyang District, Beijing 100029, China;4. Faculty of Earth Sciences, University of Silesia, Bedzinska Str. 60, 41-200 Sosnowiec, Poland;5. Nanjing Institute of Geology and Paleontology, Chinese Academy of Science, 39 East Beijing Road, Nanjing 210008, China;1. School of Geosciences in China University of Petroleum, Qingdao 266580, China;2. College of Geosciences in China University of Petroleum, Beijing 102249, China;3. State Key Laboratory of Petroleum Resources and Prospecting, Beijing 102249, China;4. Research Institute of Petroleum Exploration and Development, Huabei Petroleum Administration Bureau, Renqiu 062550, China;1. State Key Laboratory of Biogeology and Environmental Geology and School of Earth Sciences, China University of Geosciences, Wuhan 430074, China;2. Key Laboratory of Economic Stratigraphy and Paleogeography, Nanjing Institute of Geology and Paleontology, Chinese Academy of Sciences, Nanjing 210008, China;3. State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China;4. Department of Geology, University of Cincinnati, Cincinnati, OH 45221-0013, USA;1. GFZ German Research Centre for Geosciences, 14473 Potsdam, Germany;2. Institute of Geological Sciences, Freie Universität Berlin, Malteserstrasse, 74-100, Berlin 12249, Germany;3. School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK;4. School of Earth and Space Exploration, Arizona State University, Tempe 85287, AZ, United States;5. Geological Survey of Canada, Box 6000, 9860 West Saanich Road, Sidney V8L 4B2, British Columbia, Canada |
| |
| Abstract: | Organic-rich source rocks have generally been attributed to enhanced preservation of organic matter under anoxic bottom waters. Here, geochemical analysis of kerogen and whole rock samples of organic-rich (lithofacies B1) and organic-lean (lithofacies B2) laminated mudrocks of the Devonian–Carboniferous Exshaw Formation, Alberta, highlight the importance of primary production in governing the quantity and quality of organic matter. Lower Si/Al, K/Al, Ti/Al and quartz/clay ratios in lithofacies B2, similar maceral types and the laminated fabric of the two lithofacies indicate that the quality and quantity of organic matter are not related to grain size, redox or organic matter source changes. High Total Organic Carbon (TOC) and Hydrogen Index (HI), low Oxidation Index (Ox.I. ratio of oxygen functional groups to aliphatic groups derived by FTIR), lighter δ15Ntot and heavier δ13Corg isotopes indicate that kerogen of lithofacies B1 accumulated during periods of high organic-carbon production and delivery of relatively fresh, labile, well-preserved organic matter to the sea floor. In contrast, low TOC, HI, high Ox.I., heavier δ15Ntot and lighter δ13Corg isotopes indicate low primary productivity and delivery, high recycling and poor preservation of organic matter during accumulation of lithofacies B2. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
