The Geochemical Characteristics and Environmental Implications of the Paleocene–Eocene in the Jiangling Depression, Southwestern Jianghan Basin
Various isotopic and palynological indicators have shown interspersed periods of aridity and humidity for the late Paleocene to early Eocene in central China, so the paleoclimate conditions remain unclear. This research investigates the environmental characteristics of a saline lake in the Jiangling...
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MDPI AG
2024-02-01
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| Series: | Minerals |
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| Online Access: | https://www.mdpi.com/2075-163X/14/3/234 |
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| author | Kai Yan Chunlian Wang Renyi Chen Jiuyi Wang Ruiqin Li Lihong Liu |
| author_facet | Kai Yan Chunlian Wang Renyi Chen Jiuyi Wang Ruiqin Li Lihong Liu |
| author_sort | Kai Yan |
| collection | DOAJ |
| description | Various isotopic and palynological indicators have shown interspersed periods of aridity and humidity for the late Paleocene to early Eocene in central China, so the paleoclimate conditions remain unclear. This research investigates the environmental characteristics of a saline lake in the Jiangling depression, southwestern Jianghan Basin, from the Paleocene to the Eocene, using bulk-rock geochemistry in a 1280 m sediment core. The ratios of FeO/MnO, Al<sub>2</sub>O<sub>3</sub>/MgO, and C-value indicate a semi-humid to semi-arid climate in the early–middle Paleocene. There was a rapid shift to a humid climate during the late Paleocene to early Eocene, following a short time of intense dryness. The Eocene climate was arid, but experienced intermittent humidity. The variation trend of the CIA, CIW and PIA was similar to that of FeO/MnO, Al<sub>2</sub>O<sub>3</sub>/MgO, and the C-value, so chemical weathering of the surrounding rocks was controlled by climate change. The lake redox conditions in the Jiangling depression from the Paleocene to the Eocene were reconstructed using the ratios of U/Th, Ni/Co, and V/Cr. During humidity and alternations of aridity and humidity, the lake water received external water input, resulting in weak stratification, so the sediments were in oxidizing conditions. During aridity, lakes become endorheic, leading to sediments forming in reduced conditions. The salinity of the lake in the Jiangling depression from the Paleocene to the Eocene was determined through analysis of sedimentary sequences and the trend of the Sr/Ba ratio. In the early–middle Paleocene, lake salinity varied greatly. From the late Paleocene to the early Eocene, lake salinity decreased. In the Eocene, lake salinity increased and halite precipitated, but lake salinity finally decreased due to a humid climate. During the late Paleocene–early Eocene, the occurrence of multiple humid climates in the Jiangling depression were not merely regional effects. The most significant humidity was caused by a global hyperthermal (PETM), which caused a huge increase in precipitation in the whole of East Asia and even in low latitudes around the world. |
| first_indexed | 2024-04-24T17:59:49Z |
| format | Article |
| id | doaj.art-d326b224fe40457ea9c58afad2628d36 |
| institution | Directory Open Access Journal |
| issn | 2075-163X |
| language | English |
| last_indexed | 2024-04-24T17:59:49Z |
| publishDate | 2024-02-01 |
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| spelling | doaj.art-d326b224fe40457ea9c58afad2628d362024-03-27T13:56:10ZengMDPI AGMinerals2075-163X2024-02-0114323410.3390/min14030234The Geochemical Characteristics and Environmental Implications of the Paleocene–Eocene in the Jiangling Depression, Southwestern Jianghan BasinKai Yan0Chunlian Wang1Renyi Chen2Jiuyi Wang3Ruiqin Li4Lihong Liu5MNR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, ChinaMNR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, ChinaMNR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, ChinaMNR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, ChinaSchool of Earth and Space Sciences, Peking University, Beijing 100871, ChinaSchool of Earth and Space Sciences, Peking University, Beijing 100871, ChinaVarious isotopic and palynological indicators have shown interspersed periods of aridity and humidity for the late Paleocene to early Eocene in central China, so the paleoclimate conditions remain unclear. This research investigates the environmental characteristics of a saline lake in the Jiangling depression, southwestern Jianghan Basin, from the Paleocene to the Eocene, using bulk-rock geochemistry in a 1280 m sediment core. The ratios of FeO/MnO, Al<sub>2</sub>O<sub>3</sub>/MgO, and C-value indicate a semi-humid to semi-arid climate in the early–middle Paleocene. There was a rapid shift to a humid climate during the late Paleocene to early Eocene, following a short time of intense dryness. The Eocene climate was arid, but experienced intermittent humidity. The variation trend of the CIA, CIW and PIA was similar to that of FeO/MnO, Al<sub>2</sub>O<sub>3</sub>/MgO, and the C-value, so chemical weathering of the surrounding rocks was controlled by climate change. The lake redox conditions in the Jiangling depression from the Paleocene to the Eocene were reconstructed using the ratios of U/Th, Ni/Co, and V/Cr. During humidity and alternations of aridity and humidity, the lake water received external water input, resulting in weak stratification, so the sediments were in oxidizing conditions. During aridity, lakes become endorheic, leading to sediments forming in reduced conditions. The salinity of the lake in the Jiangling depression from the Paleocene to the Eocene was determined through analysis of sedimentary sequences and the trend of the Sr/Ba ratio. In the early–middle Paleocene, lake salinity varied greatly. From the late Paleocene to the early Eocene, lake salinity decreased. In the Eocene, lake salinity increased and halite precipitated, but lake salinity finally decreased due to a humid climate. During the late Paleocene–early Eocene, the occurrence of multiple humid climates in the Jiangling depression were not merely regional effects. The most significant humidity was caused by a global hyperthermal (PETM), which caused a huge increase in precipitation in the whole of East Asia and even in low latitudes around the world.https://www.mdpi.com/2075-163X/14/3/234Jiangling depressionPaleocene–Eocene saline lakeclimateredox conditionssalinity |
| spellingShingle | Kai Yan Chunlian Wang Renyi Chen Jiuyi Wang Ruiqin Li Lihong Liu The Geochemical Characteristics and Environmental Implications of the Paleocene–Eocene in the Jiangling Depression, Southwestern Jianghan Basin Minerals Jiangling depression Paleocene–Eocene saline lake climate redox conditions salinity |
| title | The Geochemical Characteristics and Environmental Implications of the Paleocene–Eocene in the Jiangling Depression, Southwestern Jianghan Basin |
| title_full | The Geochemical Characteristics and Environmental Implications of the Paleocene–Eocene in the Jiangling Depression, Southwestern Jianghan Basin |
| title_fullStr | The Geochemical Characteristics and Environmental Implications of the Paleocene–Eocene in the Jiangling Depression, Southwestern Jianghan Basin |
| title_full_unstemmed | The Geochemical Characteristics and Environmental Implications of the Paleocene–Eocene in the Jiangling Depression, Southwestern Jianghan Basin |
| title_short | The Geochemical Characteristics and Environmental Implications of the Paleocene–Eocene in the Jiangling Depression, Southwestern Jianghan Basin |
| title_sort | geochemical characteristics and environmental implications of the paleocene eocene in the jiangling depression southwestern jianghan basin |
| topic | Jiangling depression Paleocene–Eocene saline lake climate redox conditions salinity |
| url | https://www.mdpi.com/2075-163X/14/3/234 |
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