论湘中地区金矿床的控矿构造

ON THE ORE-CONTROLLING STRUCTURES OF GOLD DEPOSITS IN CENTRAL HUNAN

湘中地区金矿床据其空间分布情况,以构造岩浆带为基础,可划分为3个成矿带,①雪峰弧形钨锑金成矿带,②白马山—龙山东西向钨锑金成矿带,③苗儿山—关帝庙北东向钨锑金多金属成矿带。这3个成矿带即为湘中地区3个一级隆起构造带。成矿带中主干断裂挟持的地垒式断块上升隆起区,为钨锑金矿田集中分布区。人字型断裂、张性及张扭性裂隙、层间断裂、地层不整合面、古火山机构等为容矿构造,控制矿床(体)的分布。因此,在不同构造体系复合部位、特別是反接(横跨)复合部位、多个构造层或多个不整合而被断裂造成重叠的地段、地层与断裂或小岩体接触地段、褶皱弯曲转折及倾伏地段、古火山岩分布地段等,都是金矿床找矿的构造标志。

The gold deposits in Central Hunan, according to their spatial distribution, on the bases of tecto-magmatic zoning can be grouped into 3 metallogenic zones, that is, Xuefeng arc-shaped tungsten-antimony-gold metallogenic zone, Baimashan-Longshan latitudinally-trending tungsten-antimony-gold metallogenic zone, Miaoershan--Guandimiao northeast-trending tungsten-antimony-gold polymetallic metallogenic zone. The three metallogenic zones are three primary upwarping zones in central Hunan. The horst-type upwarpped fault block clamped by the main faults in the metallogenic zone is the concentrating distribution area for tungsten-antimony-gold orefield. The lambda-type fault, the tensile and tensile-shear fracture, the interlayer fracture, the discomformable faces of strata, the paleovolcanic mechanism and other fractures arc ore-horsting structures, which control the distribution of orebodies. Therefore, the compounding positions of different structural systems, especially the transposition (cross position), the overlaying of several structural levels or several disconformable faces caused by fault, the contact zone between the strata and faults or small intrusives, the hinge zone or plunging crown of folds and the paleovolcanic rock-distributing areas etc can all be regarded as structural criteria for prospecting gold deposits.