The Origin of the Early Proterozoic Kuandian Complex: Evidence from Geochemistry

The Kuandian Complex is scarcely preserved Early Proterozoic volcanic suite, formed2.3-2.4 Ga ago. It is located in an Early Proterozoic mobile belt bounded by the ArchaeanRangrim and Ryonggang Blocks of the northeastern Sino-Korean Craton. The Complex ismainly made up of amphibolites, gneisses, leucoleptite, leptite and layered granite. Petrologicaland geochemical studies show that the protoliths of the Complex are mainly assoctations ofbimodal volcanics and anorogenic granites. The Kuandian amphibolites are depleted in Nb, Ta,P and Ti, and enriched in LILE, e.g. K, Rb and Cs, with pronounced depletion of Sr relative toNd and Pb; La/Nb ratios are higher than 1(1.75 to 5.18). The trace element patterns of theamphibolites are similar to continental flood basalts formed by the Gondwana break-up, suchas those in South Karoo and Tasmania, which shows continental contamination. ε_(Nd) valuesranging from 0.70 to 1.94 of the Kuandian amphibolites and the relationships between Nb/Yband La/Yb suggest that contamination of basaltic magma happened in the mantle, rather thanalong the conduit. Isotope ratios of ~(208)Pb/~(204)Pb, ~(207)Pb/ ~(204)Pb, ~(206)Pb/~(204)Pb, ~(143)Nd/~(144)Ndand ~(87)Sr/~(86)Sr indicate that the magma was derived from a contaminated mantle source likeDMM or a mixture of DMM and EM2. The Kuandian Complex has Dupal anomaly, as is thecase with some continental basalts in the south hemisphere, e.g. in South Karoo and Tasmania.Petrochemical modelling proposes that the Kuandian gneiss, granite, and amphibolite camefrom the same parental magma, being products of strong fractional crystallization. Protoliths ofthe Kuandian Complex were formed in extensional tectonic setting during the transition fromcontinental crust to oceanic crust. The formation of the Kuandian Complex indicates that 2.3or 2.4 Ga ago tectonic evolution of the Sino-Korean craton was different from that of otherwell-studied Precambrian cratons, e.g. the North American shield, European platform andAustralian continent in that strong volcanic eruption resulted in its accretion. Besides, the con-taminated magma source with a Dupal anomaly for the Complex indicates that crust-mantleconvection whose scale was similar to that of the present plate tectonics had occurred at leastbefore the formation of the Kuandian Complex (2.3-2.4 Ga B.P).     

宽甸岩金预测区指示元素的优选

本文介绍了在宽甸无已知金矿床地区岩金预测工作中优选指示元素的思路。依据金矿地球化学理论,参考成矿带内已知金矿地球化学资料初选指示元素作为化学分析项目。化学分析结果出来后,编制地球化学图件时,考虑到减轻图幅负担和编图工作量,突出有用找矿信息,我们利用元素的变异性和致矿系数筛选出具有明显变异性和较高致矿性的元素,在此基础上利用元素间统计相关性和空间相关性,保留与成矿元素Au有明显相关性的元素,作为优选出的指示元素。     

辽东甬子沟滑石矿床地质特征

辽宁省宽甸县甬子沟滑石矿床分布于古元古界辽河群大石桥组三段的白云质大理岩中,矿床明显受控于北西向断裂,围岩蚀变以滑石化、透闪石化最为发育.矿床成因属中低温热液交代型层控矿床.依成矿地质条件和找矿潜力,寻找隐伏矿体、已知矿体外围是主要的找矿方向.     

宽甸县水土流失灾害与防治对策

宽甸县处于新构造运动强烈上升区,境内峰峦叠嶂,山势陡峻,沟深谷狭,暴雨频繁,地质环境十分脆弱;加之森林大量砍伐,陡坡开荒严重,垦植指数过高,超载养蚕放牧,滥采乱挖猖獗,使生态环境遭到严重破坏,水土流失程度日益加剧。严重的水土流失,导致水库淤积,河道堵塞,土层变薄,地力下降,洪水泛滥,灾害频繁,给国民经济和社会发展造成巨大损失。本文阐述了宽甸山区水土流失的形成因素和危害现状,并因地制宜提出了水土流失灾害的防治对策     

辽东半岛东北部宽甸地区南辽河群沉积时限的确定及其构造意义

辽东半岛东北部宽甸地区出露大面积南辽河群变质表壳岩系,本文通过对其中黑云石英片岩、含电气石浅粒岩和花岗质片麻岩进行精确的锆石LA-ICP-MSU-Pb定年及微区痕量元素分析,并结合锆石阴极发光(CL)图像研究来制约其原岩形成时代和变质时代,进而探讨胶-辽-吉活动带的大地构造属性。Cl图像显示锆石可以分为三类,第一类无核边结构,呈灰黑色均质特征;第二类发育核边结构,核部不发育或具弱生长环带,第三类锆石整体或者核部发育明显生长环带或具条痕状吸收特点,而后两类多数发育灰色均质边,与第一类特征一致。微区痕量元素分析结果显示,灰色均质锆石或边部具有高U(731.2×10-6～1383×10-6)、低Th(51.09～85.15×10-6)和Th/U(0.06～0.07)等特征,为变质成因;第二类锆石核部具有较高Th(97.68～219.7×10-6)和Th/U(0.21～0.27),为岩浆成因;第三类具有高Th(249.6×10-6～469.4×10-6)和Th/U(0.60～0.74),为岩浆成因。定年结果显示,所有测点均位于谐和线上或附近,三类锆石207Pb/206Pb年龄分别介于1878～1903Ma,2011～2043Ma和2082～3285Ma,前两者峰期年龄分别为1885Ma和2035Ma,表明该区南辽河群的原岩形成于～2035Ma之后,而峰期变质作用应发生在～1885Ma,其沉积作用应发生于2035～1885Ma之间;第三类锆石年龄区域上与古元古代辽吉花岗岩、火山岩及古老结晶基底年龄相吻合,暗示它们为南辽河群提供重要物源。结合前人有关辽吉花岗岩及区域构造变形、变质作用等资料,本文研究认为辽东半岛东北部宽甸地区南辽河群应形成于伸展的构造环境。     

宽甸石柱子花岗闪长岩体的矿物组合特征及其找（铜）矿标志

石柱子花岗闪长岩体形成于晚侏罗－早白垩世，岩石属钙碱系列，形成于造山带或岛弧构造环境。岩体的副矿物组合及矿物组合标型研究表明，锆石－磷灰石－锐钛矿（金红石）．锆石－锐钛矿（金红石）．锆石－磷灰石－榍石－金红石（锐钛矿）等３种副矿物组合类型；黄铁矿－黄铜矿－斑铜矿（黝铜矿）－重晶石，黄铁矿－黄铜矿，黄铜矿－方铅矿－重晶石，黄铁矿－黄铜矿－重晶石，黄铁矿－黄铜矿－辉钼矿，黄铁矿－白钨矿，黄铁矿－重晶石等７种矿石矿物组合类型，可作为本区寻找斑岩铜矿的矿物组合标志。     

辽宁省海城县桦子峪地区中,下元古界再划分

以构造—地层法为准则进行区域填图,在桦子峪地区发现有三个彼此之间呈不整合接触的构造层。各个构造层分别遭受了不同类型的区域变质作用。据此,将本区的中、下元古界(原辽河群)分解成三套不同的地层—宽甸群、草河群和辽阳群。同位素年代学资料确定它们的主变形变质幕分别发生在2100Ma、1850Ma和1400Ma。     

辽宁宽甸万宝源钼矿地质特征及成因机制

辽宁宽甸万宝源钼矿位于燕山期石柱子花岗闪长岩体与寒武纪碳酸盐岩地层的接触部位。钼矿体依其围岩岩性和构造位置的不同可以分为石英斑岩裂隙型、花岗闪长岩裂隙型和破碎蚀变带石英脉型。硫、氢、氧同位素的测试结果及分析表明成矿物质主要来自重熔的深部硅铝质地壳, 成矿流体以岩浆水为主, 并混有古大气水。该区存在两期成矿: Ⅰ期形成矽卡岩型Cu-Fe矿体; Ⅱ期形成斑岩型和石英脉型Mo矿体, 以斑岩型为主。两期成矿均为岩浆期后热液的产物。     

二人沟硼矿床断裂构造与找矿关系探讨

二人沟硼矿床发育有大规模北北东向的逆掩断层,但在以往的工作中对断层的特征了解得不甚清楚,以致于找矿工作未取得满意的效果。通过对原有资料的分析研究,总结出该断层的特征,有效地指导了找矿工作,取得了寻找隐伏矿体的重大进展。     

辽宁宽甸县砖庙沟硼矿构造与找矿

通过对砖庙沟硼矿区进行研究,对比区域和矿区构造认为东西向构造和北北东向构造具有控矿作用。本次研究工作查明了砖庙沟矿段的矿体分布情况,认识了砖庙沟矿段FⅡ—16断层及其下盘矿体的分布规律。以此为指导,在FⅡ—16逆掩断层下盘找到隐伏硼矿体,扩大了矿山规模,取得良好找矿效果,对延长矿山寿命和寻找硼矿有重要意义。