| 大别山北麓石炭纪盆地沉积和构造研究 |
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| 引用本文： | 李宝芳,马文璞,张惠良,赵志根,李贵东.大别山北麓石炭纪盆地沉积和构造研究[J].地学前缘,2000,7(3):153-167. |
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| 作者姓名： | 李宝芳 马文璞 张惠良 赵志根 李贵东 |
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| 作者单位： | 中国地质大学,北京,100083 |
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| 基金项目： | 国家教育部博士学科基金资助项目，地质行业科技发展基金资助项目“秦岭大别山北麓石炭系沉积体系及其构造涵义的研究”!(2293,1993—199 |
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| 摘 要： | 大别山加里东构造带北麓的石炭系为残留海盆地沉积 ,分布限制在潢川—固始—肥中断裂以南和信阳—商城—金寨—舒城断裂以北 ,保存在南翼向南倒转并有逆冲推覆构造的复式向斜中 ,中部被燕山期花岗岩侵入体破坏。排除构造重复 ,石炭系总厚 >2 0 0 9m (掩盖部分未计 ) ,按岩石地层单元分 5个组 ,各组之间均为断层接触。自下而上花园墙组为以复理石为代表的深水浊积扇和具有向上变细序列的陡坡扇沉积 ;杨山组为辫状河和滨岸辫状三角洲含煤沉积 ;道人冲组为辫状河、辫状三角洲、扇三角洲及滨浅海沉积 ;胡油坊组分布最广 ,为微咸水盆地陡坡扇、浊积扇沉积 ,有特征的复理石和滑塌沉积 ;杨小庄组为碎屑海岸含煤沉积。下统和上统的界限位于道人冲组中下部厚层砾岩的底部。古水流方向以自南指向北占优势 ,物源主要来自南侧的大别山区。石炭系下统砾岩为远源硅质正砾岩 ,含大量脉石英砾石 ,母岩为岩浆热液成因 ,现已无保存 ;上统砾岩为近源陡坡环境形成的复成分、多杂基的副砾岩 ,为浊积砾岩 ,其中脉石英砾石明显减少 ,含千枚岩和沉积岩砾石 ,母岩主要来自南侧的信阳群 /佛子岭群等。复理石、滑塌、浊积砾岩的存在表明石炭系具陡坡陆缘海活动大陆边缘的沉积特征 ,并发现有少量火山岩碎屑 ,可能形成于弧后盆地。稀?
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| 关 键 词： | 大别山北麓 石炭系 复理石 浊积砾岩 陡坡陆缘海沉积 弧后盆地 |
A STUDY ON SEDIMENTOLOGY AND TECTONICS OF THE CARBONIFEROUS BASIN IN THE NORTHERN FOOTHILLS OF THE DABIE MOUNTAINS,CHINA |
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| LI Bao-fang,MA Wen-pu,ZHANG Hui-liang,ZHAO Zhi-gen,LI Gui-dong.A STUDY ON SEDIMENTOLOGY AND TECTONICS OF THE CARBONIFEROUS BASIN IN THE NORTHERN FOOTHILLS OF THE DABIE MOUNTAINS,CHINA[J].Earth Science Frontiers,2000,7(3):153-167. |
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| Authors: | LI Bao-fang MA Wen-pu ZHANG Hui-liang ZHAO Zhi-gen LI Gui-dong |
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| Abstract: | The Carboniferous basin distributed along the northern foothills of the Dabie Mountains is preserved as a synclinorium with thrusts superimposed on its inverted south slope. A granite body intruded in the central part of the basin. Despite the duplicate strata caused by tectonics the total thickness of the strata is more than 2 009 metres. The Carboniferous can be divided into 5 formations, and they are all contacted by faults. From the bottom to the top the Huayuanqiang Formation is mainly represented by flysch facies of turbidite fan and steep fan. The Yangshan Formation consists of braided fluvial and braided delta coal bearing deposits. The Daorenchong Formation consists of braided fluvial, braided delta, steep slope fan, and shoreline and shallow marine deposits. The Huyoufang Formation is represented by steep slope turbidite fan and glide breccia deposits. The Yangxiaozhuang Formation consists of clastic shoreline coal bearing deposits. The boundary between the Lower and the Upper Carboniferous is located at the bottom of the thick conglomerates occurring in the lower part of Daorenchong Formation. The paleocurrent directions are predominately from the south to the north, implicating that the source area is the Dabie Mountains. The conglomerates of the Lower Carboniferous are siliceous orthoconglomerates, whereas those of the Upper Carboniferous are paraconglomerates characterized by mixed component of clasts and breccia and with plenty matrix, and belong to turbidity conglomerates. They are gravity flow and gliding deposits formed in a steep slope of a semi brackish water basin. In the Lower Carboniferous a great quantity of vein quartz clastics indicate the magmatic hydrothermal mother rocks. The Carboniferous was developed in a back arc basin, because the paraconglomerates and the gliding deposits were developed in an active continental margin, and some volcanic clastics occurred in the sediments. This conclusion is supported by the rare earth elements (REE) distribution pattern characterized by rich in light REE and poor in heavy REE. This back arc basin is the south extension of the North China Plate, the strata are very thick and characterized by steep slope environment deposits, and demonstrate its extension origin, but the thrust and folded structures are the result of compression. Thus this basin is a back arc rift basin developed on a marginal continent during the Carboniferous and changed into a back arc foreland basin afterwards. The volcanic island arc located on the south of this basin and a relict shallow sea might be distributed on the north. But most of these sediments were disappeared during the collision of the North China Plate with the north margin of the Yangtze Plate represented by the Dabie uplift zone. The suture of these two plates is located on the south of this basin, possibly along the Shangcheng—Jinzhai—Shucheng Fault. The Huangchuan—Gushi—Feizhong Fault in the north is the tectonic boundary between the back arc basin and the North China Platform. The organic materials of the Carboniferous here are over maturity, and the R 0 value decreases eastwards from the granite intrusive body in Shangcheng. Natural gas pools may be found in the southern Hefei basin if the Carboniferous could be preserved under the overlying Mesozoic and Cenozoic. |
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| Keywords: | northern foothills of the Dabie Mountains Carboniferous flysch turbidity conglomerates steep slope marginal sea deposits back arc basi |
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