湖北省主要煤系成煤环境及找煤方向浅析

Elementary Analysis of Main Coal Measures Coal-forming Environment and Coal Looking Orientation in Hubei Province

湖北省主要煤系地层是下二叠统"梁山煤系"、上二叠统"龙潭煤系"和上三叠统—下侏罗统"香溪煤系"。"梁山煤系"和"龙潭煤系"主要分布在鄂东南、鄂西南地区,"香溪煤系"零星分布在鄂州—赤壁、远安—当阳、巴东—兴山、利川等地。研究认为:二叠纪成煤环境属近海型,而晚三叠世、早侏罗世属于内陆型。控制聚煤作用的主要因素有:①成煤环境为滨岸沼泽相区,沼泽发育之前沉积物若为砂质、粉砂质岩类,则含煤性好,反之若为泥质或粘土质岩类,则含煤性差;②煤系沉积的早期沉积基底剥蚀夷平为坳陷地带,到中晚期坳陷逐渐增大,能形成宽阔的聚煤(盆地)带;③地壳沉降幅度大,升降速度平稳,泥炭沼泽发育时间长;④地壳振荡次数频繁,沉积旋回多,煤层厚度较大,含煤性好,反之,沉积旋回少或不完整,煤层少,且薄,含煤性差。通过分析有利的聚煤因素,提出了各煤系的找煤方向。

Main coal measures strata in the Hubei Province have Lower Permian ＂Liangshan coal measures＂, Upper Permian ＂Longtan coal measures＂ and Upper Triassic-Lower Jurassic ＂Xiangxi coal measures＂. The former two coal measures are distributed in southeastern and southwestern Hubei areas, while the latter scattered distributed in Ezhou-Chibi, Yuanan-Dangyang, Badong- Xingshan and Lichuan areas. The study has considered that, the Permian coal-forming environment belongs to offshore type; while during Late Triassic and Early Jurassic belongs to inland type. Main factors to control coal accumulation have： （1） coal -forming environment was paralic bog facies, if the sediments before the bog development are sandy, silty rocks thus have good coal-forming properties, while the argillaceous or clayey rocks, poor coal-forming properties; （2）the basement for coal measures deposit after denudating and leveling then become into depression, through to the deposition of coal measures to middle and late stages, depression expanded to wide coal accumulation zone （basin）; （3）crustal subsided by a wide margin, stable elevation rate, long peat bog development duration; （4）frequent crustal oscillation, multiple sedimentary cycles made thicker coal seams and good coal-bearing properties, on the contrary, less sedimentary cycles or not integrated made less and thinner coal seams, poor coal-bearing properties. Through beneficial coal accumulation factor analysis, put forward coal looking orientation for each coal measures.