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引用本文:孙宁亮,钟建华,倪良田,郝兵,罗可,曲俊利,刘闯,杨冠群,曹梦春. 鄂尔多斯盆地南部上三叠统延长组物源分析及热演化[J]. 中国地质, 2019, 46(3): 537-556.
SUN Ningliang,ZHONG Jianhua,NI Liangtian,HAO Bing,LUO Ke,QU Junli,LIU Chuang,YANG Guanqun,CAO Mengchun. Provenance analysis and thermal evolution of Upper Triassic Yanchang Formation in the Southern Ordos Basin[J]. Geology in China, 2019, 46(3): 537-556(in Chinese with English abstract).
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鄂尔多斯盆地南部上三叠统延长组物源分析及热演化
孙宁亮1, 钟建华1, 倪良田1, 郝兵1, 罗可1, 曲俊利2, 刘闯1, 杨冠群3, 曹梦春1
1.中国石油大学(华东)地球科学与技术学院, 山东 青岛 266580;2.自然资源部油气资源战略研究中心, 北京 100034;3.中国地质大学(北京)能源学院, 北京 10083
摘要:
本文以鄂尔多斯盆地南部旬邑地区上三叠统延长组为例系统研究了其物源区属性及热演化。采用碎屑锆石LA-ICP-MS定年的方法,通过分析砂岩样品中碎屑锆石U-Pb的年龄结构及组成,明确了其物源区属性。研究表明:长7碎屑锆石存在225~264 Ma、276~408 Ma、413~458 Ma、727~851 Ma、1249~1749 Ma和1868~2469 Ma 6个年龄区间,分别对应于印支期、海西期、加里东晚期、Rodinia超大陆裂解、晋宁运动早中期和古元古代的构造热事件,研究区物源复杂,主要来自于北秦岭西段、秦祁造山带、西秦岭、祁连造山带东段及天山-兴蒙造山带,阿拉善地块和盆地北部山区也可能为本区提供物源,古水流分析表明研究区的物源方向为近南部。通过磷灰石裂变径迹年龄分析及热史模拟,明确了研究区在100 Ma左右的早白垩世经历了重要的构造热事件,是油气藏形成的重要时期。自此以后,又经历了4次比较明显的热演化,100~43 Ma为缓慢抬升阶段,进入部分退火,冷却速率大概在0.44℃/Ma,43~36 Ma为一快速抬升阶段,冷却速率达到4.3℃/Ma,36~24 Ma为又一期的缓慢抬升,冷却速率在0.52℃/Ma左右,从24~17 Ma样品又经历了一次快速的抬升过程,冷却速率在1.5℃/Ma左右。研究区43 Ma以来的抬升剥蚀明显受到印度板块与亚欧板块碰撞的影响。
关键词:  碎屑锆石  磷灰石  物源分析  热演化  延长组  鄂尔多斯盆地
DOI:10.12029/gc20190307
分类号:P597
基金项目:国家自然科学基金(41272088)及中央高校基本科研业务专项资金(15CX06002A)联合资助。
Provenance analysis and thermal evolution of Upper Triassic Yanchang Formation in the Southern Ordos Basin
SUN Ningliang1, ZHONG Jianhua1, NI Liangtian1, HAO Bing1, LUO Ke1, QU Junli2, LIU Chuang1, YANG Guanqun3, CAO Mengchun1
1.School of Geosciences, China University of Petroleum, Qingdao 266580, Shandong, China;2.Research Center of Oil & Gas Resources, Ministry of Natural Resources, Beijing 100034, China;3.School of Energy Resources, China University of Geosciences(Beijing), Beijing 100083, China
Abstract:
The sedimentary sources and thermal evolution of Upper Triassic of Yanchang Formation in Xunyi area of Southern Ordos Basin were studied in this paper. With the method of LA-ICP-MS, the detrital zircons ages and compositions of sandstone samples from the study area were analyzed so as to investigate the sedimentary sources. The results show that there exist six age stages of the Chang 7 detrital zircons, i.e., 225-264 Ma, 276-408 Ma, 413-458 Ma, 727-851 Ma, 1249-1749 Ma and 1868-2469 Ma, corresponding to the tectonic movements of Indo-Chinese, Hercynin, late Caledonian, Rodinia break-up, early-middle Jinning movement and Paleoproterozoic periods. Sedimentary sources are complex in the study area, and they mainly came from the western section of northern Qinling, Qin-Qi orogenic belt, West Qinling, eastern section of Qilian orogenic belt, and Tianshan-Xingmeng orogenic belt. Alxa block and northern area of the basin might have been the sedimentary sources of the study area. Paleo-current statistics indicate that the source direction was close to the southern part of the study area. Apatite fission track analysis and thermal history reconstruction were carried out, and the results confirm that the study area experienced an essential tectonic thermal event at 100 Ma in the early Cretaceous period of Late Mesozoic, which was an important period of oil and gas formation. There existed four relatively evident thermal evolution periods after that:100 to 43 Ma was a slow uplift stage and experienced partially annealing with a cooling rate of around 0.44℃/Ma; 45 to 36 Ma was a rapid uplift stage and the cooling rate came to 4.3℃/Ma; 36 to 24 Ma was another slow uplift stage with the cooling rate about 0.52℃/Ma; 24 to 17 Ma was a rapid uplift stage and the cooling rate came to 1.5℃/Ma. However, the India-Asia collision has influenced the uplift and erosion in the study area since 43 Ma.
Key words:  detrital zircons  apatite  provenance analysis  thermal evolution  Yanchang Formation  Ordos Basin