| Stratigraphy of the Triassic?Jurassic Boundary Successions of the Southern Margin of the Junggar Basin, Northwestern China |
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| 作者姓名： | SHA Jingeng Vivi VAJDA PAN Yanhong Linda LARSSON YAO Xiaogang ZHANG Xiaolin WANG Yaqiong CHENG Xiansheng JIANG Baoyu DENG Shenghui CHEN Siwei PENG Bo |
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| 作者单位： | 1 State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, the Chinese Academy of Sciences, Nanjing 210008, China; 2 Department of Earth and Ecosystem Sciences, Lund University, 22362 Lund, Sweden; 3 PetroChina Xinjiang Oil Field Company, Keramay 834000, China; 4 School of Earth Sciences and Engineering, Nanjing University, Nanjing 210093, China; 5 Research Institute of Petroleum of Exploration and Development, PetroChina, Beijing 100083, China |
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| 基金项目： | This work is supported by Special Basic Research Program of Ministry of Science and Technology of China (Grant No. 2006FY120300) and National Committee of Stratigraphy of China. V. Vajda acknowledges the financial support provided by Swedish Research Council (VR, Grant No. 2007?4509). V. Vajda is a Swedish Royal Academy of Sciences Research Fellow founded through the Knut and Alice Wallenbergs Foundation. It is also a contribution to UNESCO?IUGS IGCP Project 506. |
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| 摘 要： | The Triassic?Jurassic (Tr?J) boundary marks a major extinction event, which (~200 Ma) resulted in global extinctions of fauna and flora both in the marine and terrestrial realms. There prevail great challenges in determining the exact location of the terrestrial Tr?J boundary, because of endemism of taxa and the scarcity of fossils in terrestrial settings leading to difficulties in linking marine and terrestrial sedimentary successions. Investigation based on palynology and bivalves has been carried out over a 1113 m thick section, which is subdivided into 132 beds, along the Haojiagou valley on the southern margin of the Junggar Basin of the northern Xinjiang, northwestern China. The terrestrial Lower Jurassic is conformably resting on the Upper Triassic strata. The Upper Triassic covers the Huangshanjie Formation overlaid by the Haojiagou Formation, while the Lower Jurassic comprises the Badaowan Formation followed by the Sangonghe Formation. Fifty six pollen and spore taxa and one algal taxon were identified from the sediments. Based on the key-species and abundance of spores and pollen, three zones were erected: the Late Triassic (Rhaetian) Aratrisporites?Alisporites Assemblage, the Early Jurassic (Hettangian) Perinopollenites?Pinuspollenites Assemblage, and the Sinemurian Perinopollenites?Cycadopites Assemblage. The Tr?J boundary is placed between bed 44 and 45 coincident with the boundary between the Haojiagou and Badaowan formations. Beds with Ferganoconcha (?), Unio?Ferganoconcha and Waagenoperna?Yananoconcha bivalve assemblages are recognized. The Ferganoconcha (?) bed is limited to the upper Haojiagou Formation, Unio?Ferganoconcha and Waagenoperna?Yananoconcha assemblages are present in the middle and upper members of the Badaowan Formation. The sedimentary succession is interpreted as terrestrial with two mainly lake deposit intervals within Haojiagou and Badaowan formations, yielding fresh water algae and bivalves. However, the presence of brackish water algae Tasmanites and the marine?littoral facies bivalve Waagenoperna from the Badaowan Formation indicate that the Junggar Basin was influenced by sea water caused by transgressions from the northern Tethys, during the Sinemurian.
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| 关 键 词： | Biostratigrapy Triassic?Jurassic Hettangian?Sinemurian palynology bivalve Haojiagou of Junggar Basin northwestern China |
| 收稿时间： | 2010/10/1 0:00:00 |
| 修稿时间： | 2010/12/30 0:00:00 |
Stratigraphy of the Triassic-Jurassic Boundary Successions of the Southern Margin of the Junggar Basin,Northwestern China |
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| Authors: | SHA Jingeng Vivi VAJDA PAN Yanhong Linda LARSSON YAO Xiaogang ZHANG Xiaolin WANG Yaqiong CHENG Xiansheng JIANG Baoyu DENG Shenghui CHEN Siwei and PENG Bo |
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| Institution: | SHA Jingeng~(1,*),Vivi VAJDA~(2,**),PAN Yanhong~1,Linda LARSSON~2,YAO Xiaogang~1,ZHANG Xiaolin~1,WANG Yaqiong~1,CHENG Xiansheng~3,JIANG Baoyu~4,DENG Shenghui~5,CHEN Siwei~1 and PENG Bo~1 1 State Key Laboratory of Palaeobiology and Stratigraphy,Nanjing Institute of Geology and Palaeontology,the Chinese Academy of Sciences,Nanjing 210008,China 2 Department of Earth and Ecosystem Sciences,Lund University,22362 Lund,Sweden 3 PetroChina Xinjiang Oil Field Company,Keramay 834000,China 4 School of Earth Science... |
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| Abstract: | The Triassic–Jurassic (Tr–J) boundary marks a major extinction event, which (～200 Ma) resulted in global extinctions of fauna and flora both in the marine and terrestrial realms. There prevail great challenges in determining the exact location of the terrestrial Tr–J boundary, because of endemism of taxa and the scarcity of fossils in terrestrial settings leading to difficulties in linking marine and terrestrial sedimentary successions. Investigation based on palynology and bivalves has been carried out over a 1113 m thick section, which is subdivided into 132 beds, along the Haojiagou valley on the southern margin of the Junggar Basin of the northern Xinjiang, northwestern China. The terrestrial Lower Jurassic is conformably resting on the Upper Triassic strata. The Upper Triassic covers the Huangshanjie Formation overlaid by the Haojiagou Formation, while the Lower Jurassic comprises the Badaowan Formation followed by the Sangonghe Formation. Fifty six pollen and spore taxa and one algal taxon were identified from the sediments. Based on the key‐species and abundance of spores and pollen, three zones were erected: the Late Triassic (Rhaetian) Aratrisporites‐Alisporites Assemblage, the Early Jurassic (Hettangian) Perinopollenites–Pinuspollenites Assemblage, and the Sinemurian Perinopollenites–Cycadopites Assemblage. The Tr–J boundary is placed between bed 44 and 45 coincident with the boundary between the Haojiagou and Badaowan formations. Beds with Ferganoconcha (?), Unio–Ferganoconcha and Waagenoperna–Yananoconcha bivalve assemblages are recognized. The Ferganoconcha (?) bed is limited to the upper Haojiagou Formation, Unio–Ferganoconcha and Waagenoperna–Yananoconcha assemblages are present in the middle and upper members of the Badaowan Formation. The sedimentary succession is interpreted as terrestrial with two mainly lake deposit intervals within Haojiagou and Badaowan formations, yielding fresh water algae and bivalves. However, the presence of brackish water algae Tasmanites and the marine‐littoral facies bivalve Waagenoperna from the Badaowan Formation indicate that the Junggar Basin was influenced by sea water caused by transgressions from the northern Tethys, during the Sinemurian. |
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| Keywords: | Biostratigrapy Triassic-Jurassic Hettangian-Sinemurian palynology bivalve Haojiagou of Junggar Basin northwestern China |
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