【摘要】 福建永安县李坊重晶石矿床是特大型受变质沉积矿床。围岩为寒武纪浅变质（绿片岩相,黑云母带）硅、泥质夹砂屑正常沉积岩系,经受两期变质作用和至少4期变形作用。主变质期（D₁）发生在先,伴生与层理（S₀）平行的千枚状构造（S₁）。主变形期（D₂）发生在后,形成SN向、缓倾伏、倒转的I_c—Ⅱ型复武褶皱, 在千枚岩类中伴生肉眼上可见的视连续劈理,对S₀,S₁发生强烈的置换作用,致使区域地质构造长期被误认为单斜岩层,矿层中出现的小褶皱和寄生褶皱被误认为同生揉皱,反复褶皱的两个矿层被描写成多层序的,连续性差的几百个小矿体。笔者通过先构造后地层的工作程序,利用人工露头,观测各期各类构造形迹的产状、特征及其相互关系。划分构造模式、建立构造系列,测制了矿段构造—岩性地质图、并依据各期各类构造形迹的空间关系编制钻孔地质构造剖面图,预测地下矿层的廷伸情况和展布规律。继而进行几百个薄片的显微构造研究,并借助电镜扫描、岩组分析等手段,从微观上进一步揭示了变形与变质的关系,分析了各期褶皱和次生叶理的特征,相互关系,演化规律和成因问题。更多还原

【Abstract】 The Lifang barite deposite of Yongyan in Fujian is a giant metamorphosed sedimentary deposit. Its wall rocks consist of the Cambrian low-grade metamorphic （green shist facies, biotite zone） psammire-siliceous and argillaceous sedimentary rocks, which have undergone metamorphism for two stages and deformation for four stages at least. When the main metamorphic stage （D₁） first happened, a phyllitic structure （S₁） paralleled to bedding （S₀） had been formed. There is a gentle plunging and overturned composite fold （1_c-Ⅱ type） trending S-N formed at the second deformation stage. Apparent continuous cleavage is also presented in the phyllites, resulting in a striking replacement of S₀, S₁, and so the regional geological tectonics is mistaken for monoclinal stratum for a long time, and the small fold and parasitic fold in ore bed are also mistakenly considered as contemporaneous fold. Two ore beds of repeated fold are divided into several hundreds of small ore bodies, multisequence and discontinuous.By means of the work program of studying the structure before stratigraphy, having observed various structural occurrences and features and their mutual relation of the different stages measured from outcrops in field, the writer divided the structural pattern, established the structural series, and made the structure-lithological characters geological map in the ore block. On the basis of the drilling data and their special relations of various structural features, the geological structural sectiort maps have also beendrawn. It is on the above basis that the writer predicates the special distri bution rules of ore beds in underground. Then, the relation between deformation and metamorphism, and characteristics, relationship, evolutonary rule and genesis of folds and secondary floliations of various stages have been further discussed by hundreds of microstrucrural thin sections under the scanning electron microscope and petrofabric analysis, etc.更多还原