甘肃省景泰盆地晚三叠世古地理环境及聚煤规律研究  

Study on Late Triassic Paleogeographical Environment and Coal Accumulation Pattern in Jingtai Basin, Gansu Province

作　　者：王海中 丁安明 Wang Haizhong Ding Anming(No. 133 Exploration Team, Gansu Bureau of Coal Geological Exploration, Baiyin, Gansu 730913)

机构地区：[1]甘肃煤田地质局一三三队,甘肃白银730913

出　　处：《中国煤炭地质》2016年第12期14-20,共7页Coal Geology of China

摘　　要：在甘肃省景泰盆地内三叠系上统南营儿群(T3n)为一套巨厚的陆相碎屑岩沉积建造,极少形成具有工业价值的可采煤层,而近几年在景泰盆地内发现大量煤炭赋存,初步认为成煤时代为晚三叠世,但对此盆地研究程度较低。通过对景泰盆地古地理环境及后期构造的分析研究,将研究区内的三叠系上统南营儿群(T3n)含煤岩系由下至上划分为A、B、C、D四个岩性段,煤层主要赋存于煤系上部,即D、C、B三个岩性段;确定景泰盆地晚三叠世早期以河床相为主,中后期为浅湖相、堤岸亚相、河床相沼泽相及泥炭沼泽相的沉煤环境;盆地沉积从B→C→D段的过程中,成煤环境从B→C→D也逐渐变好,D段所含煤层最厚,含煤系数最大;确定景泰盆地内煤层呈东西向带状分布,煤层主要分布于白岩子勘查区中部至郭家台勘查区Ⅺ勘探线附近范围内。在郭家台勘查区东部和白岩子勘查区的西部煤层含煤性最好;确定研究区为复式褶皱和断裂并存的复杂构造盆地。褶皱轴向与断裂构造线方向基本平行,近东西向平行展布,受褶皱构造的影响,岩煤层倾角较大。The upper Triassic Nanyinger Group （T3n） in the area is a set of very thick terrigenous clastic sedimentary formation, rarely formed industrial value mineable coal seams. But during recent years, substantial coal resources have been found in the Jingtai Basin, and tentatively determined the coal-forming age is Late Triassic Epoch, but research degree is low. Through analytic study of paleogeo- graphical environment and subsequent structures in the basin, partitioned the Nanyinger Group coal-bearing rock series into D, C, B and A four lithologic sectors from top to bottom. Coal seams are mainly hosted in D, C and B three sectors. During the early Late Triassic Epoch deposited mainly channel facies; middle and late stages mainly shallow lacustrine facies, levee subfacies, channel facies, swamp facies and peat bog facies coal-forming environments. During the basin sedimentary process from B→C→D, coal-forming environment become gradually better; D sector contains thickest coal seams with largest coal-bearing coefficient. Coal seams in the basin present EW zonal distribution, mainly distributed in the range from the middle Baiyanzi exploration area to XI line nearby in the Guojiatai exploration area. Best coal-bearing property coal seams are in the eastern Guojiatai exploration area and western Baiyanzi exploration area. The study area is determined as a complex structural basin with coexistence of compound folds and faults. Fold axial and fault structural lineament are basically parallel, extending near EW; impacted by folded structures, dip angles of strata and coal seams are rather large.

关 键 词：三叠系上统南营儿群(T3n)含煤地层 构造 古地理背景 沉积环境 赋煤特征 

分 类 号：P618.11[天文地球—矿床学]