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引用本文:林 进1,2 李 云1,2 何 剑1. 鄂尔多斯延长探区本溪组物源及沉积体系分析[J]. 中国地质, 2013, 40(5): 1542-1551.
LIN Jin1,2, LI Yun1,2, HE Jian1. An analysis of the source and the sedimentary system of the Carboniferous Benxi Formation in Yanchang area of Ordos Basin[J]. Geology in China, 2013, 40(5): 1542-1551(in Chinese with English abstract).
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鄂尔多斯延长探区本溪组物源及沉积体系分析
林 进1,2 李 云1,2 何 剑1
作者单位
林 进1,2 李 云1,2 何 剑1 1. 延长石油集团油气勘探公司陕西 延安 7160002. 西北大学地质系陕西 西安 710069 
摘要:
提要:本文通过对钻井岩心、野外露头样品及薄片观察描述以及阴极发光、分析化验资料的综合应用,从矿物组分及成因类型、古水流特征、稀土元素的富集规律等方面对鄂尔多斯延长探区本溪组物源方向进行了综合判定,在此基础上对沉积相分布及演化进行了分析。研究表明,延长探区石炭系本溪组砂岩颗粒自北向南具有粒度由粗变细、磨圆度由低变高的趋势;石英组分阴极发光类型以暗褐色、浅-深棕色为主,具变质岩型成因类型;岩屑组分以变质岩岩屑为主,达85.1%;野外露头古水流方向测量结果显示出其具有北部、东北→南部、西南方向的趋势;稀土元素的分配规律与盆地东北缘大青山古陆类似。综合判定研究区本溪组物源主要来自北部的阴山—阿拉善古陆。晚石炭世本溪组本2期为鄂尔多斯地区上古生界沉积发育史的一个重要转折,研究区受区域上缓慢沉降海水自东部侵入的影响,形成了浅海泥质陆棚、障壁岛-潟湖及潮坪沉积体系;本1期整体面貌与本2期类似,受进一步海侵影响,泥质陆棚及潟湖面积有所扩大;砂体连通性平行海岸线方向好。
关键词:  物源分析  沉积  本溪组  石炭系  延长探区  鄂尔多斯盆地
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An analysis of the source and the sedimentary system of the Carboniferous Benxi Formation in Yanchang area of Ordos Basin
LIN Jin1,2, LI Yun1,2, HE Jian1
Abstract:
Abstract:By investigating data extracted from well cores, field outcrop samples, thin sections, cathodoluminescence images and the laboratory tests, the authors conducted a comprehensive study of the Carboniferous Benxi Formation in Yanchang area of Ordos Basin and then deduced its source directions from the angles of the mineral composition, genetic type, paleocurrent features, and enrichment regularities of rare earth elements. On such a basis, the authors analyzed the sedimentary facies distribution and evolution. It is revealed that from north to south in the study area, the sandstone grains decrease in size and increase in psephicity; the quartz cluster cathodoluminescence images are mainly fuscous, light-dark brown in color, indicating metamorphic genesis. The debris component is chiefly metamorphic debris, which is up to 85.1%. The paleocurrent of field outcrop moved northward, from northwest southward and southeastward. the distribution of the rare earth elements is quite similar to the Daqingshan old land at the northeast edge of the basin. It is thus concluded that the Benxi Formation primarily originated from Yinshan-Alxa in the north. The second stage of Benxi Formation in late Carboniferous epoch constituted a major turning point in the Upper Palaeozoic evolutionary history of Ordos. Due to the invasion of the slowly-subsiding sea water from the east, the study area formed a system composed of shallow argillaceous shelf, barrier island-lagoon and lagoon. The first stage was similar to the second stage in general features, but had larger argillaceous shelf and lagoon because of the intense water invasion, which had a good performance in the sand body continuity in parallel with the coastline.
Key words:  source analysis  sedimentary system  Benxi Formation  Carboniferous  Yanchang exploratory area  Ordos Basin