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冀西北金矿集中区是我国华北地台北缘金矿成矿带的重要组成部分,区内金矿主要产于水泉沟碱性杂岩体及邻近的太古宙变质岩内。Ａｒ－Ａｒ同位素年龄测定结果显示,金矿床成矿年龄（１７２～１８８Ｍａ）与水泉沟碱性杂岩体的形成年龄（３０４～３０６Ｍａ）相差达１２０Ｍａ。综合研究推断金矿床不是碱性岩浆直接演化产物,而是在燕山期构造－－岩浆活动影响下,地下循环热流体对矿源岩－－碱性杂岩体淋滤、萃取,形成富含金的成矿热 相似文献
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冀西北水泉沟杂岩体及与其有关金矿床的40Ar-39Ar同位素年代学研究 总被引：9，自引：3，他引：6
《地质论评》2000,46(6):621-627
冀西北金矿集中区是我国华北地台北缘金矿成矿带的重要组成部分,区内金矿主要产于水泉沟碱性杂岩体及邻近的太古宙变质岩内。Ar-Ar同位素年龄测定结果显示,金矿床成矿年龄（172～188Ma）与水泉沟碱性杂岩体的形成年龄（304～306Ma）相差达120Ma。综合研究推断金矿床不是碱性岩浆直接演化产物,而是在燕山期构造—岩浆活动影响下,地下循环热流体对矿源岩——碱性杂岩体淋滤、萃取,形成富含金的成矿热液,最终在有利的成矿构造部位沉淀富集的结果。因此本区的金矿床均属于与碱性杂岩体有关的改造型热液金矿。 相似文献
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冀西北水泉沟杂岩体及与其有关金矿床的~(40)Ar-~(39)Ar同位素年代学研究 总被引：8，自引：2，他引：6
冀西北金矿集中区是我国华北地台北缘金矿成矿带的重要组成部分,区内金矿主要产于水泉沟碱性杂岩体及邻近的太古宙变质岩内。Ar-Ar同位素年龄测定结果显示,金矿床成矿年龄(172～188 Ma)与水泉沟碱性杂岩体的形成年龄(304～306 Ma)相差达120 Ma。综合研究推断金矿床不是碱性岩浆直接演化产物,而是在燕山期构造—岩浆活动影响下,地下循环热流体对矿源岩——碱性杂岩体淋滤、萃取,形成富含金的成矿热液,最终在有利的成矿构造部位沉淀富集的结果。因此本区的金矿床均属于与碱性杂岩体有关的改造型热液金矿。 相似文献
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张家口水泉沟正长岩杂岩体成因的REE和Sr、Nd、Pb同位素证据 总被引：13，自引：0，他引：13
水泉沟杂岩体位于尚义 赤城断裂的南侧,侵位于太古宙桑干群变质岩中。岩体形成于晚加里东至早海两期。其稀土元素含量为8.543×10~(-6)～211.6×10~(-6),随着岩石的CaO、MgO、FeO、Fe_2O_3含量降低,SiO_2、K_2O、Na_2O含量增大,稀土含量减小,稀土分布模式由右倾直线型变为近平直的“～”型。在铅同位素构造模式图上杂岩体落在地幔铅同位素演化线附近。在ε_(Nd)-ε-(Sr)图解上处于地幔演化线的下方。杂岩体的钕模式年龄低于围岩桑干群的形成年龄。岩体可能来源干上地幔与下地壳太古宙变质杂岩混熔作用所形成的正长岩岩浆。 相似文献
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东坪金矿产于水泉沟偏碱性杂岩体与太古宇桑干群变质岩之内接触带,矿石工业类型为石英脉和蚀变岩型,以前者为主.矿脉带走向为NNE,主要载金矿物为石英、黄铁矿、镜铁矿、黄铜矿和碲金矿,金成色937~990,矿化蚀变主要是钾长石化和硅化;肉红色钾长石化是东坪金矿乃至赋存于水泉沟杂岩体中所有金矿的典型特征.矿化共分5个阶段,其中第2、3两个阶段,即镜铁矿-自然金-石英阶段和多金属硫化物-自然金-石英阶段为主要成矿阶段.水泉沟杂岩体在东坪金矿成矿过程中,不仅提供了热动力,而且提供了成矿物质和矿化剂;太古宙桑干群涧沟河组提供了部分成矿物质,近E-W向尚义-崇礼-赤诚深大断裂控制了水泉沟金矿田的产出,而NNE和NW向两组裂隙则控制了东坪金矿矿体的产出. 相似文献
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冀北水泉沟岩体西段锆石U-Pb年代学及Hf同位素研究 总被引：2，自引：2，他引：0
冀北水泉沟碱性正长杂岩体位于华北克拉通北缘中段,主要岩性为正长岩、石英正长岩、碱性正长岩、角闪正长岩、角闪二长岩和碱长花岗岩等.为了避开后期热液蚀变作用的影响,作者采集了远离东坪-后沟金矿田的水泉沟岩体西段无蚀变的角闪二长岩、角闪正长岩样品,并对这些代表性岩石进行了锆石U-Pb年代学和锆石Hf同位素研究.LA-ICP-MS锆石U-Pb年龄表明,角闪二长岩结晶年龄为372.7±2.5Ma,角闪正长岩结晶年龄为372.7±2.4Ma,二者年龄结果一致,表明水泉沟碱性杂岩体西段形成于晚泥盆世.角闪二长岩的锆石εHf(t)＝-12.4~-8.9,两阶段Hf模式年龄为1.93~2.16Ga,平均2.05Ga.角闪正长岩的锆石εHf(t)＝-13.2~-11.1,两阶段Hf模式年龄为2.07~2.21Ga,平均2.13Ga.考虑到两种岩石的模式年龄与华北基底变质岩的形成年龄相近,我们初步认为水泉沟碱性杂岩体西段角闪二长岩和角闪正长岩可能主要来源于富集岩石圈地幔部分熔融形成的镁铁质岩浆与古老的中下地壳变质岩部分熔融形成的长英质岩浆混合的结果.野外地质和地球化学数据表明,水泉沟碱性杂岩体形成于晚造山阶段的张性构造环境. 相似文献
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<正> 河北省崇礼县东坪金矿位于冀北中部金矿成矿带中。大地构造位置处在中朝准地台北部边缘,燕山沉降带与内蒙地轴交界南侧,水泉沟偏碱性杂岩体的内接触带。它是我国首次在偏碱性杂岩中找到的大型金矿床。这种金矿新类型的发现具有重要的理论意义和经济价值。1 成矿地质背景 水泉沟岩体南北两侧的桑干群谷咀子组为一套太古宙中深变质岩系,岩性以斜长角闪岩、斜长角闪片麻岩、变粒岩、混合岩为主。岩体东、西侧为中元古界、侏罗系火山碎屑 相似文献
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河北张家口水泉沟岩体SHRIMP年代学研究及其意义 总被引：26，自引：4，他引：26
采用先进的 SHRIMP测年技术对河北水泉沟碱性杂岩体进行了年龄测定，获得东坪金矿区水泉沟岩体二长岩锆石 U- Pb年龄为 (390± 6)Ma，后沟金矿区水泉沟岩体正长岩年龄 (386± 6)Ma，比较可信地确定了水泉沟岩体的成岩时代为晚加里东期—早海西期。这表明北部温都尔庙-西拉木伦河加里东俯冲造山运动强烈地影响本区，水泉沟岩体是这次运动的产物。根据前人测得的东坪和后沟金矿床蚀变围岩钾长石的 Ar- Ar和 K- Ar年龄，金矿化的时代是中生代燕山期，与岩体的成岩年龄有 200 Ma的时差，成因上可能与碱性杂岩体关系不大，因此，东坪和后沟等金矿床可能不属于碱性岩型金矿床。 相似文献
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冀北水泉沟杂岩体的同位素地球化学特征及其成因意义 总被引：5，自引：0，他引：5
张招崇 《长春地质学院学报》1997,27(1):36-43
水泉沟杂岩体的δ１８Ｏ‰值除个别样品高于１０‰或低于５．５‰外，大多数在５．５‰～１０．０‰之间。其三组铅同位素比值明显高于本区古界桑干燥变质岩，并位于上地慢和下地壳铅增长线之间，利用Ｒｂ－Ｓｒ等时线求得锶同位素初始值为０．７０６１８±０．０００１４，利用Ｆａｕｒｅ提出了的二元混合锶模型求得岩浆源区由约６４％的上地幔组分和约３６％的地壳组分组成。通过对其Ｏ，Ｐｂ和Ｓｒ同位素综合分析得出，岩浆起源于 相似文献
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水泉沟岩体为岩浆成因,岩体的侵位深度2~3km,侵位时代为印支期,划分为4种岩石组合.水泉沟岩体是一个钾质-高钾质的钙碱性、弱碱性和碱性岩石共存的杂岩体.岩石化学成分变异图解证明岩浆存在两种演化趋势,一是酸性演化趋势:辉石闪长岩→角闪二长岩(包括二长岩)→石英碱长正长岩→碱长花岗岩;二是碱性演化趋势:正长岩→霓辉正长岩→碱长正长岩.同时也探讨了这两种演化趋势的内在机理. 相似文献
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铜陵矿集区燕山期中酸性侵入岩地球化学特征及其地质意义 总被引：12，自引：2，他引：12
铜陵矿集区燕山期中酸性侵入岩由橄榄玄粗质系列和高钾钙碱性系列岩石组成,两者的岩石化学和地球化学特征存在差异,相互间不存在岩浆分异演化关系.稀土和微量元素以及O、Pb、Sr、Nd同位素研究表明,高钾钙碱性系列侵入岩的原始岩浆以下地壳深变质岩部分熔融岩浆为主,在有幔源玄武质岩浆注入的情况下先于橄榄玄粗质系列岩浆侵位形成;起源于富集地幔的碱性玄武岩与有限的地壳物质发生同化混染并通过结晶分异作用(AFC)形成了橄榄玄粗质系列侵入岩.下地壳或岩石圈地幔拆沉继而环流热幔上涌是本区侵入岩形成的直接起因;同时,侵入岩浆的强烈活动也是本区构造环境由挤压向伸展转换的标志. 相似文献
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和龙地区太古宙变质深成侵入体的地质地球化学特征 总被引：1，自引：1，他引：1
本文论述了和龙地区太古宙变质深成侵入体的岩石学，岩石化学，地球化学特征。首次提出了该区是以变质深成侵入体为主体的认识。通过其地球化学特征的研究，对太古宙岩浆的成因和演化提出了新的认识，这些认识将对吉林省太古宙变质岩的研究和成矿作用起到了重要的指导作用。 相似文献
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Located at western portion of northern margin of North China craton, the Baotou–Bayan Obo district is one of the most important Fe–REE–Nb and Au metallogenic provinces in China. Presently, about 52 gold deposits and prospects have been discovered, explored and mined, among which Shibaqinhao, Laoyanghao, Houshihua, Saiyinwusu, Wulashan and Donghuofang are the most important ones. All these gold occurrences can be subdivided into three groups (or types) according to its host rocks: (1) hosted by Archean high-grade metamorphic rocks; (2) hosted by Proterozoic sedimentary rocks; (3) hosted by or related to Hercynian alkaline intrusive rocks. The first group contains the Shibaqinhao, Laoyanghao and Houshihua gold deposits. Gold mineralization at these three deposits occurs within Archean amphibolite, gneiss and granulite as gold-bearing quartz veins and veinlet groups containing native gold, electrum, pyrite and chalcopyrite. The Saiyinwusu deposit belongs to the second group, and occurs within Proterozoic sandstone, quartzite and carbonaceous slate as quartz veins and replacement bodies along the fracture zones. Pyrite, marcasite, arsenopyrite, native gold and electrum are identified. The third group includes the Wulashan, Donghuofang and Luchang deposits. Gold mineralization at these three deposits occurs predominantly within the Hercynian alkaline syenite or melagabbro stocks and dyke swarms or along their contacts with Archean metamorphic wall rocks as K-feldspar–quartz veins, dissemination and veinlets. Pyrite, galena, chalcopyrite, native gold and calaverite are major metallic minerals.δ34S value of sulfides (pyrite, galena and pyrrhotite) separates from groups 1 and 2 varies from −4.01‰ to −0.10‰ and −3.01‰ to 2.32‰, respectively. δ34S values of Archean and Proterozoic metamorphic wall rocks for groups 1 and 2 deposits range from −20.2‰ to −17.0‰ and −15.8‰ to −16.2‰, respectively. The values are much lower than their hosted gold deposits. All these pyrite separates from Hercynian alkaline intrusions associated with the gold deposits show positive δ34S values of 1.3‰ to 4.8‰, which is higher than those Precambrian metamorphic wall rocks and their hosted gold deposits. δ34S values of the sulfides (pyrite and galena) from the Donghuofang and Wulashan deposits (group 3) increase systematically from veins (−14.8‰ to −2.4‰) to the Hercynian alkaline igneous wall rocks (2.8‰ to 4.8 ‰). All of these deposits in groups 1, 2 and 3 show relatively radiogenic lead isotopic compositions compared to mantle or lower crust curves. Most lead isotope data of sulfides from the gold ores plot between the Hercynian alkaline intrusions and Precambrian metamorphic wall rocks. Data are interpreted as indicative of a mixing of lead from mantle-derived alkaline magma with lead from Precambrian metamorphic wall rocks.Isotopic age data, geological and geochemical evidence suggest that the ore fluids for the groups 1 and 2 deposits were generated during the emplacement of the Hercynian alkaline syenite and mafic intrusions. The Hercynian alkaline magma may provide heat, volatiles and metals for these groups 1 and 2 deposits. Evolved metamorphic fluids produced by the devolatilization, which circulated the wall rocks, were also progressively involved in the alkaline magmatic hydrothermal system, and may have dominate the ore fluids during late stage of ore-forming processes. Most of these gold deposits hosted by Archean high-grade metamorphic rocks occur at or near the intersections of the NE- and E–W-trending fracture systems. The ore fluid of the group 3 deposits may have resulted from the mixing of Hercynian alkaline magmatic fluids and evolved meteoric waters. The deposits are believed to be products of Hercynian alkaline igneous processes along deep-seated fault zones within Archean terrain. 相似文献
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Copper mineralisation is associated with rocks of basic/intermediate composition which occur as a widespread swarm of relatively small irregularly-shaped bodies within the gneissic terrain of the Okiep District. These basic rocks comprise the so-called Koperberg noritoid suite of Namaqualand and constitute one of the three major copper producers in South Africa. While a metasomatic origin was briefly favoured for the noritoids, most researchers have emphasized the cross-cutting nature of the noritoids relative to their host rocks and prefer an origin involving magmatic injection. High noritoid 87Sr/86Sr initial ratio values indicated to some workers that mobilisation of suitable crustal materials was more attractive than intrusion of mantle-derived melts to account for the origin of the noritoid suite. The present study has shown that the structure, texture and mineralogy of the noritoids do not lend themselves to interpretation of the noritoids as pristine intrusive rocks, and indicate that the noritoids have undergone high-grade metamorphism after emplacement. The geochemistry of the noritoid suite reveals a pronounced alkaline affinity and mineralogical control of the chemistry characterises the rocks as cumulates. The dimensions of the noritoids appear unfavourable for development of cumulate rocks and it is considered possible that the present configuration of the noritoids results from dismemberment of larger intrusive bodies as a result of shear deformation during high-grade metamorphism. It has not been possible to identify a magma parent to the noritoid suite, but we believe the parent to have been an alkaline mantle-derived magma which suffered contamination by granitic anatects in the lower crust. Recognition of the metamorphic history of the Namaqualand noritoids renders a comparison between them and the Caraiba noritoids of interest. 相似文献