西秦岭北缘德乌鲁矽卡岩型铜矿床地质特征及成矿模式讨论

Geological Characteristics and Metallogenic Model of Dewulu Skarn-type Copper Deposits in West Qinling,Gansu Province

甘肃夏河县德乌鲁矽卡岩型铜矿床产于商丹缝合带南侧的西秦岭段。德乌鲁岩体为花岗闪长岩岩体,并伴有同源岩浆脉动侵入形成的花岗闪长斑岩和微晶石英闪长岩,该岩体接触带多已发生矽卡岩化,形成透辉石石榴石矽卡岩和矽卡岩化大理岩等。岩体围岩为二叠系石关组的一套浅海相碎屑岩夹碳酸盐岩沉积。矿区主要工业矿体赋存于矽卡岩中,多集中于侵入体岩脉穿插较复杂地段,且无一例外的在侵入体内凹或岩枝凸出处为富矿地段。通过对资料研究,表明德乌鲁矽卡岩富铜矿的形成是燕山期深部地壳熔融形成岩浆携带较丰富的成矿物质,于岩体冷凝成岩过程中交代围岩形成"矽卡岩型"和"热液型"混合铜矿。燕山期花岗闪长岩、花岗闪长斑岩(脉)、石英闪长(玢)岩、透辉石石榴子石矽卡岩及矽卡岩化大理岩发育地区,并出现孔雀石、蓝铜矿、褐铁矿化等氧化矿物的地段,以及伴有磁异常、铜次生晕和低电阻率异常地段,与德乌鲁铜矿区特征相似,为找矿有利地段。因此,提出龙得岗—美武新寺地区为具有较大铜成矿潜力区,建议加强研究和勘查工作。

The Dewulu skarn-type copper deposit is located in western Qinling of south Shangdan Suture,Gansu Province.The intrusion of Dewulu ismainly granodiorite.The impulsive intrusion of the comagmatic magma formed granodiorite porphyry and micro-crystal quartz diorite,the later metalliferous magmatic hydrothermal filled and replaced the wall rock and formed skarnization marble and diopside-garnet skarn.The main industrial orebody occurs in the skarn.Mineraliza-tion concentrated in the complex zone that intercalated by intrusive dykes.The ore shoot occurs in the cove of the intrusion or the extending area of the apophyse.During the Indosinian move-ment in Middle-Late Triassic,deep earth crust melted and became magma,containing abundantmineral resources.Research results show that magma of deep crust melts carried abundant metal-logenic materials to replace the wall rock and make the ore mineral precipitate in the condensation and diagenetic process,forming skarn-typeand hydrothermal-type mixed copper deposit.Areas-with early Yanshanian granodiorite,granite diorite porphyry （vein）,quartz diorite porphyrite and diopside-garnet skarn,skarnization marble,area containing malachite,azurite,ferritization, and other oxidized minerals,accompanied by area with magnetic anomaly,secondary halo of cop-per and low resistivity,are favorable prospecting places.Thus,the Longdegang-Meiwuxinsi dis-trict is considered to be a favorable area for ore prospecting.More exploration and research work should be conducted there.