摘要:
通过野外构造变形解析得出,江西上饶船坑—铜山一带铜矿床及其相关的侵入岩体主要受中生代推覆构造控制。推覆构造面总体倾向 SE,表现为波状起伏。推覆构造外来岩系为中石炭统至上三叠统碳酸盐岩及页岩、泥质粉砂岩,原地岩系为下侏罗统地层。外来岩系变形大多呈同斜褶皱,并伴生不同规模逆冲断层及顺层滑脱构造,局部存在平卧及箱状褶皱;原地岩系变形亦较强烈。推覆构造表现为自 SE 向 NW的运动。成矿岩体大多呈相互平行的薄层状,岩席侵位于上述推覆体外来岩系顺层滑脱带中。岩石地球化学及同位素年代学分析表明成矿岩体具挤压机制下岩浆弧特征,形成于170 Ma。结合推覆构造卷入的地层、研究区外围德兴一带同类型侵入岩与中生代推覆构造关系的讨论,认为上饶船坑—铜山一带与铜多金属矿相关的中生代石英二长斑岩为受同时代推覆构造变形控制的同构造岩浆岩,可能与中生代古太平洋板块向中国东南大陆俯冲导致岩石圈增厚发生大规模推覆构造,并诱发下地壳重熔岩浆侵位至浅表顺层滑脱空间有关。
Abstract:
This paper gives the conclusion that the copper deposit and the ore-forming rocks in Chuankeng-Tong-shan area in Jiangxi Province were controlled by Mesozoic thrust-fault,by tectonic deformation analysis in the field.The thrust-fault’s surface undulate and overall dip towards SE.The exotic block composed of carbonate, shale and pelitic siltstone from middle Carboniferous to upper Triassic and the autochthon crop out Lower Jurassic. Deformations of exotic block shows isoclinal fold,associated with different scale of thrust fault and bedding detach-ment structure.Some recumbent and box folds are local existence.The thrust-fault moves from SE to NW.The ore-forming rocks intrusive to the thrust bedding detachment as mutual paralleled sheet.Other research in rock geochemistry and isotopic geochronology showed that the magma formed in magmatic arc under extensional envi-ronment,around 1 70 Ma.According to the stratigraphic age,the relationship of Mesozoic thrust-fault and the granite in Dexing area,the result inferred that the magma was syntectonic intrusion rocks,and controlled by the thrust-fault.And this probably results from the subduction of Pacific plate and southeast continental of China,and leads to the incrassation lithosphere and large scale nappe,then induces the lower earth crust remelting and magma invade.
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