| 松辽盆地晚白垩世陆表古温度定量重建 |
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| 引用本文： | 秦健铭,陈积权,高远,席党鹏,王成善.松辽盆地晚白垩世陆表古温度定量重建[J].沉积学报,2020,38(4):759-770. |
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| 作者姓名： | 秦健铭 陈积权 高远 席党鹏 王成善 |
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| 作者单位： | 1.中国地质大学（北京）地球科学与资源学院，北京 100083 |
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| 基金项目： | 国家自然科学基金项目41790450中央高校基本科研业务费优秀教师基金项目2652018119中国地质大学（北京）大学生创新创业训练计划项目2018AB004 |
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| 摘 要： | 松辽盆地嫩江组一、二段是形成于晚白垩世的湖相沉积，保留了丰富的陆地古气候信息。对松辽盆地LD6?7井嫩江组一、二段矿物学、地球化学分析及陆表古温度重建，其全岩矿物以黏土矿物含量最多（平均46.2%），石英含量次之（平均21.7%），斜长石和钾长石含量较低。多种风化指数显示嫩江组一、二段具有中等强度的化学风化作用。物源区、搬运和成岩过程对沉积物化学组成的影响分析结果显示:1）降水量较大，2）有一定强度的物理剥蚀，3）分选和沉积再循环作用较弱，4）成岩作用较弱，5）原岩为酸性岩。基于τNa?MAT转换方程，得到松辽盆地LD6?7井嫩江组一、二段沉积时期的陆表古温度为14.2 ℃，属于温带—亚热带气候，与前人研究结果一致。研究证明利用元素地球化学手段重建古温度的方法在松辽盆地嫩江组一、二段具有可行性，可为今后“深时”陆地古气候定量研究提供借鉴。
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| 关 键 词： | 松辽盆地 嫩江组 矿物学 元素地球化学 古温度 |
| 收稿时间： | 2019-06-24 |
Quantitative Paleotemperature Reconstruction of Late Cretaceous Nenjiang Formation in Songliao Basin: A case study of the LD6?7 Core |
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| Institution: | 1.School of Earth Sciences and Resources, China University of Geosciences (Beijing), Beijing 100083, China2.State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences (Beijing), Beijing 100083, China |
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| Abstract: | The Nenjiang Formation Members 1+2 (K2n1+2), which formed during the Late Cretaceous in the Songliao Basin, is a lacustrine mudstone deposition, on which abundant terrestrial paleoclimate information is preserved. This study examined mineralogy, as well as the major elemental and trace elemental geochemistry, of K2n1+2 and attempted to reconstruct the terrestrial paleotemperature quantitatively. Results show that the bulk rock mineralogy is mainly composed of clay mineralogy (46.2% average), minor quartz (21.7% average). and negligible plagioclase and K?feldspar. Values of the Chemical Index of Alteration (CIA, 63 average), Mafic Index of Alteration for Oxidative condition (MIA?O, > 64), Plagioclase Index of Alteration (PIA, > 53), and Weathering Index of Parker (PIA, > 44) indicate medium chemical weathering intensity of K2n1+2. The analysis of the sediment chemical composition by provenance, transportation, and diagenesis satisfies the precondition of calculating the annual mean temperature (MAT) by element geochemistry: (1) High annual precipitation rate (> 400 mm/yr), (2) moderate physical erosion rate, (3) no significant sedimentary sorting and recycling, (4) weak diagenesis, and (5) Chinese acid rock as the protolith. This study suggests a MAT of ~14.19 °C based on the τNa-MAT transfer function from K2n1+2 of the LD6?7 core in Songliao Basin. This estimated MAT is consistent with previous research results, which is a subtropical climate. It is proven that the method of reconstructing paleotemperature by means of element geochemistry is feasible for K2n1+2 of the LD6?7 core in Songliao Basin, which can provide a reference for the quantitative study of the terrestrial paleoclimate concerning "deep time" in the future. |
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