CAJ | 학술논문

胶东和小秦岭是我国排名前两位的金矿产地,根据对这两个地区的实地野外考察、室内研究及对已有大量研究成果的总结,我们认为胶东与小秦岭地区的金矿床均可归入造山型金矿的范畴,它们分别形成于增生型造山体制和碰撞型造山体制.胶东金矿床形成于早白垩世(130～120Ma左右)与洋壳俯冲(增生)造山相关的活动大陆边缘环境,矿床主要产于中生代花岗岩岩体中,严格受断裂带(NNE向或NE向为主)控制,成矿流体具有低盐度高CO_2含量的特征,He-Ar同位素研究显示成矿过程有幔源物质的加入.综合金矿床及中生代岩浆岩(特别是与成矿近同时的早白垩世郭家岭花岗岩及基性岩脉)的地质地球化学特征与成岩成矿动力学,我们提出在俯冲的太平洋板块后退的背景下,胶东地区增厚地壳中的榴辉岩相下地壳及下伏岩石圈地幔发生两阶段拆沉,强烈的壳幔相互作用最终导致了早白垩世普遍的岩浆活动及金的爆发成矿的模式.小秦岭地区金矿床主要以大型含金石英脉的形式产出于太华群变质基底的脆性-韧性剪切带(EW向为主)中,而与区域内燕山期大型花岗岩岩基没有直接联系,矿床地质特征(如低盐度高CO_2,以变质流体为主的成矿热液)与造山型金矿吻合,He-Ar同位素特征表明金矿床形成时有幔源物质的加入.小秦岭地区脉状Au-Mo矿床印支期成矿年龄(215～256Ma,辉钼矿Re-Os)表明印支期是小秦岭地区金成矿的主要时期,小秦岭金矿属于陆陆(华北与扬子)碰撞造山过程中形成的造山型金矿.
효동화소진령시아국배명전량위적금광산지,근거대저량개지구적실지야외고찰、실내연구급대이유대량연구성과적총결,아문인위효동여소진령지구적금광상균가귀입조산형금광적범주,타문분별형성우증생형조산체제화팽당형조산체제.효동금광상형성우조백성세(130～120Ma좌우)여양각부충(증생)조산상관적활동대륙변연배경,광상주요산우중생대화강암암체중,엄격수단렬대(NNE향혹NE향위주)공제,성광류체구유저염도고CO_2함량적특정,He-Ar동위소연구현시성광과정유만원물질적가입.종합금광상급중생대암장암(특별시여성광근동시적조백성세곽가령화강암급기성암맥)적지질지구화학특정여성암성광동역학,아문제출재부충적태평양판괴후퇴적배경하,효동지구증후지각중적류휘암상하지각급하복암석권지만발생량계단탁침,강렬적각만상호작용최종도치료조백성세보편적암장활동급금적폭발성광적모식.소진령지구금광상주요이대형함금석영맥적형식산출우태화군변질기저적취성-인성전절대(EW향위주)중,이여구역내연산기대형화강암암기몰유직접련계,광상지질특정(여저염도고CO_2,이변질류체위주적성광열액)여조산형금광문합,He-Ar동위소특정표명금광상형성시유만원물질적가입.소진령지구맥상Au-Mo광상인지기성광년령(215～256Ma,휘목광Re-Os)표명인지기시소진령지구금성광적주요시기,소진령금광속우륙륙(화북여양자)팽당조산과정중형성적조산형금광.
Jiaodong and Xiaoqinling areas are two largest gold metallogenic provinces in China.On the basis of field observation and compilation and evaluation of available research progresses and data in these two areas,we argued that gold deposits in both Jiaodong and Xiaoqinling are orogenic gold deposits,but formed in different geological settings.The Jiaodong gold deposits formed in an accretionary orogeic setting while the Xiaoqinling was in a collisional orogeic setting.The Jiaodong gold deposits are likely formed in an active continental margin related to subduction of the Pacific plate in early Cretaceous(ca.130～120Ma).They are mainly hosted in Mesozoic granitoids and controlled by NNE-trend or NE-trend fault zones.The ore-forming fluids have low salinity and high CO_2 contents,and the He-Ar isotopic systematics in fluid inclusion show fingerprint of mantle-derived fluid input.As the consequence of roll-back of the Pacific slab and increase in density of lower crust when changed into eclogite after thickened by compression,part of the lithospheric mantle and lower crust were delaminated,which led to intensive crust-mantle interaction and extensive magmatism with formation of gold deposits in Jiaodong.In contrast,in the Xiaoqinling area gold deposits are mainly controlled by brittle-ductile shear zones(mainly EW-trend)in metamorphic basement rocks of Taihua Group,and show no close connection with Mesozoic granites.Geological features of these deposits(e.g.,hydrothermal fluid with low salinity and high CO_2 contents,and originated mainly from metamorphic water)are consistent with those of orogenic gold deposits worldwide.Some vein-type Au-Mo deposits have been dated at 215～256Ma through method of molybdenite Re-Os geochronology,which support the idea that the gold deposits in the Xiaoqinling area mainly formed in Indosinian period,when collision between North China Craton and Yangtze Block took place.