福建省天湖山煤矿区F_(31)推覆断层及找煤方向探讨

Discussion on the F_(31) Nappe and Coal Looking Orientation in Tianhushan Coalmine Area, Fujian Province

福建省天湖山煤矿区处于闽西南坳陷东条带,推覆构造极其发育,以F31和F1两条推覆断层表现最为突出。据矿区开采资料证实,F31断层下盘童子岩组为—总体向西倾斜向南倾伏、轴向NNE的紧密线状褶皱,断层较稀少;上盘构造复杂,断层发育,由F31所派生的低序次断层往往为逆掩或逆冲断层,与主断层面组成"入"字型构造,造成童子岩组地层多次重复,同时派生了更低序次的断层组成羽毛状构造。通过对F31推覆断层特征以及应力场分析研究,认为其演进过程为:童子岩期前后的成岩沉积—印支期侧向挤压形成褶皱—印支运动及其后由于侧向挤压形成软弱滑动面及断裂—燕山早期侧向挤压造成低角度推覆断层。根据该矿区构造研究成果,提出了矿区外围及深部的5个找煤方向。

The Tianhushan coalmine area is situated at the east strip of the southwestern Fujian depression, nappe structures are quite developed, especially the F31 and F1 nappes have stood out. According to mining data, generally, the Tongziyan Formation of the F31 footwall is a NNE appressed linear fold, dipping west plunging south with seldom faults; while the hanging wall has complex structure with developed faults, low-order faults of F31 are usually reverse thrust or over-thrust fault formed λ-type structure with the master fault and caused recurrence of Tongziyan Formation strata repeatedly and derived even lower ordered faults to form featherlike structure. Through analysis of Fn nappe stress field and characteristics, considered that the cvolutional process of the nappe is： lithogenetic sedimentation before and after Tongziyan stage-lateral compressive folding during the Indo-Chinese epoch-the Indosinian movement and after lateral compression formed flaccid sliding planes and faults-early Yanshanian stage lateral compression formed low angle nappe structure. Based on the structural research results, have put forward 5 coal looking orientations for peripheral and depth of the coalmine area.