内蒙古东部霍林河盆地霍林河组的年龄:来自锆石U-Pb测年和孢粉组合的证据(英文)  

AGE OF THE HUOLINHE FORMATION IN THE HUOLINHE BASIN, EASTERN INNER MONGOLIA, CHINA: EVIDENCE FROM U-Pb ZIRCON DATING AND PALYNOLOGICAL ASSEMBLAGES

作　　者：史恭乐[1,2] 李建国 谭覃 董重[1,2] 李秋立 吴琼 章伯乐[6] 尹素心 HERRERA Fabiany HERENDEEN Patrick S. CRANE Peter R. SHI Gong Le;LI Jian Guo;TAN Tan;DONG Chong;LI Qiu Li;WU Qiong;ZHANG Bo Le;YIN Su Xin;HERRERA Fabiany;HERENDEEN Patrick S.;CRANE Peter R.(State Key Laboratory of Palaeobiology and Stratigraphy,Nanjing Institute of Geology and Palaeontology,Chinese Academy of Sciences,Nanjing 210008;Center for Excellence in Life and Paleoenvironment,Chinese Academy of Sciences,Nanjing 210008;University of Chinese Academy of Sciences,Beijing 100049;State Key Laboratory of Lithospheric Evolution,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029;School of Earth Sciences and Engineering,Nanjing University,Nanjing 210023;Qingdao Research Institute of Geotechnical Prospecting and Surveying,Qingdao 266030;Chicago Botanic Garden,Glencoe,IL 60022,USA;Yale School of the Environment,Yale University,New Haven,CT 06511,USA;Oak Spring Garden Foundation,Upperville,VA 20184,USA)

机构地区：[1]中国科学院南京地质古生物研究所,现代古生物学和地层学国家重点实验室,江苏南京210008 [2]中国科学院生物演化与环境卓越创新中心,江苏南京210008 [3]中国科学院大学,北京100049 [4]中国科学院地质与地球物理研究所,岩石圈演化国家重点实验室,北京100029 [5]南京大学地球科学与工程学院,江苏南京210023 [6]青岛市勘察测绘研究院,山东青岛266030 [7]芝加哥植物园,Glencoe,伊利诺伊60022,美国 [8]耶鲁大学环境学院,纽黑文,康涅狄格06511,美国 [9]橡树泉园林基金会,Upperville,弗吉尼亚20184,美国

出　　处：《地层学杂志》2021年第1期69-81,共13页Journal of Stratigraphy

基　　金：中国科学院战略性先导科技专项(B类)(XDB26000000);国家自然科学基金(41790454、41802014、41772014);美国国家科学基金(DEB-1748286);中国科学院青年创新促进会(2017359)共同资助。

摘　　要：内蒙古东部霍林河盆地霍林河组是我国最重要的下白垩统含煤地层之一。该组产出大量不同种类且保存完好的植物化石,但因为缺乏海相沉积和火山岩夹层,我们对这套地层的精确年龄认知不足。我们最近在扎鲁特旗扎哈淖尔露天煤矿霍林河组发现了火山灰层,基于钻孔数据的地层分析显示该火山灰层位于霍林河组下含煤段的底部。二次离子质谱(SIMS)锆石U-Pb年代学研究得出的该火山灰层沉积年龄为125.6±1.0 Ma(巴雷姆期晚期–阿普特期最早期),这一结果与激光剥蚀-等离子体质谱(LA-ICP-MS)对同一样品分析得出的年龄一致。火山灰层保存的孢粉化石组合以裸子植物花粉和蕨类及苔藓的孢子为主,被子植物花粉非常稀少,且仅有棒纹粉Clavatipollenites一种。这一孢粉组合支持火山灰层的年龄为巴雷姆期晚期至阿普特期最早期。本研究为认识整个霍林河组的年龄及火山灰层上覆地层保存的重要植物化石的最大年龄提供了重要数据。The Huolinhe Formation in the Huolinhe Basin, eastern Inner Mongolia is one of the most important Lower Cretaceous coal-bearing strata in China, yielding abundant, diverse, and well-preserved plant fossils. Its precise age, however, is poorly known due to lack of associated marine deposits and volcanic beds. Here we present U-Pb zircon ages, and the associated palynological assemblages of an ash layer of the Huolinhe Formation recently discovered at the Zhahanaoer open-cast coal mine in Jarud Banner. Stratigraphic analyses based on boreholes suggest that the ash layer occurs near the bottom of the "lower coal-bearing member" of the Huolinhe Formation. U-Pb zircon geochronology using the SIMS method constrains the depositional age of the ash layer to be 125.6±1.0 Ma(late Barremian–earliest Aptian), and this is consistent with the result from LA-ICP-MS analyses of the same sample. A late Barremian–earliest Aptian age for the ash layer is also supported by the palynological assemblage associated with the layer, in which the pollen of gymnosperms and the spores of ferns and bryophytes are dominant, angiosperm pollen is very rare and represented by only Clavatipollenites. This study contributes important new data for understanding the age of the entire Huolinhe Formation and also provides a more precise maximum age for the key plant fossils preserved in the deposits above the ash layer.

关 键 词：霍林河组 早白垩世 含煤盆地 U-Pb地质年代学 孢子花粉 内蒙古 

分 类 号：P534.53[天文地球—古生物学与地层学]