北祁连山石居里铜矿硅、铅、硫同位素组成特征

石居里铜矿是北祁连山典型的塞浦路斯型铜矿,通过对矿石和围岩的硅、铅和硫同位素研究,作者认为,硅同位素组成δ30Si(-0.9‰～-0.2‰)与火山岩的δ30Si范围一致(落在火山岩范围内),由此可知是火山成因的产物。矿石中黄铁矿、黄铜矿的铅同位素组成同各矿区范围玄武岩的铅同位素组成相近,以此为线索结合Rona(1983)的试验规律,推断本区成矿金属主要来源于蚀变玄武岩。硫同位素δ34S值变化于1.5‰～8.88‰,矿化剂硫来源于火山岩源与海水源的不同比例混合。     

北祁连山中西段塞浦路斯型铜矿特征、成矿作用及找矿标志

本文总结北祁连山中西段塞浦路斯型铜矿特征及找矿标志,获得如下认识:1成矿环境为奥陶纪亲弧扩张脊(岛弧扩张脊和弧后扩张脊),容矿岩石为蛇绿岩套上部火山-沉积岩系;矿床成矿金属组合为铜锌,贫铅;2矿床地质模型为蘑菇状,蘑菇茎代表沿热液通道的柱状矿体,蘑菇伞代表在热液喷流口周围海底展开的透镜状、似层状矿体,伞翼之下为基性火山岩,伞上常覆盖碧玉岩,成矿环境不稳定时,缺失碧玉岩。近喷流口位置矿体Cu>Zn,远喷流口位置矿体Cu 关键词: 北祁连山/亲弧扩张脊/塞浦路斯型铜矿     

北祁连塞浦路斯型铜矿床地质地球化学特征对比研究

北祁连奥陶纪典型的塞浦路斯型铜矿床均产出于北祁连山弧后盆地的蛇绿岩中,西段石居里矿床赋存的蛇绿岩带生成环境为近弧的弧后盆地扩张脊环境,东段猪嘴哑吧矿床赋存的蛇绿岩生成环境为近陆的弧后盆地扩张脊环境。东西段构造环境差异导致北祁连山东西段塞浦路斯型铜矿在矿体形态和成矿元素富集程度上存在差异。西段以柱状、似透镜状为主,东段以透镜状为主;成矿元素上东段相比西段更富锌和硫。硫同位素分析,两段均为海水中硫酸盐和玄武岩中硫酸盐混合沉淀结果,东段比西段海水混入程度低。Pb同位素研究显示,Pb主要来自幔源。流体包裹体成分显示西段石居里以海水成因为主,而东段猪嘴哑吧则为火山热液流体成因,成矿温度均为中低温。     

北祁连山石居里辉长岩的同位素年龄及其地质意义

首次利用锆石U-Pb方法测得北祁连山西段石居里辉长岩的生成年龄为(457.9±1.2)Ma.在空间上,石居里辉长岩与石居里铜矿紧密相关,石居里辉长岩位于石居里铜矿的下部;在时间上,虽然目前尚无石居里铜矿的成矿时代年龄,但研究认为与石居里辉长岩同属加里东期,而且成岩时代早于成矿时代,因此推测石居里辉长岩为可能为石居里铜矿提供了热源.由于该区有较多的中酸性岩体存在,该成岩时代的确定对于在该区寻找塞浦路斯型块状硫化物矿床有重要的理论和实际意义.     

北祁连山古海底火山作用与成矿

概要介绍了北祁连山造山造山之前的构造火山夺浆演化历史,成矿类型和成矿背景条件。文章指出：在北祁连山早古生代洋盆开合过程中,相伴发生的大规模海相火山同作用和受海底热液循环体系制约的块状硫化物成矿作用,是该造山带地质历史发展中两个最鲜明的特色,也是该区地质研究中两个最为关键且互相关联的应当给以特别关注的领域。     

北祁连山石居里沟富铜矿床成矿特征

讨论北祁连山石居里沟富铜矿床成矿特征,通过分析认为：成矿环境为中奥陶世弧后扩张脊,容矿岩石为蛇绿岩套上部火山岩或火山－沉积岩系,矿体赋存部位受海底裂隙系统的控制,含矿热液起源于海水与玄武岩在高温下的反应,成矿金属元素主要来自火山岩,矿化剂硫来自二者。     

北祁连塞浦路斯型硫化物成矿构造环境研究──与现代劳海盆对比

北祁连塞浦路斯型硫化物矿床形成于中-晚奥陶世弧后蛇绿岩的上部,成矿作用与区内火山活动、张性断裂活动和构造运动相关,热液循环通道主要有火山裂隙系统和熔岩冷却裂隙等,成矿位置与循环通道一致。区域性大断裂是深部高温热液的主要通道,且东段矿化剂S的来源较西段更深,指示更大的断裂延展深度。北祁连塞浦路斯型硫化物矿床的成矿作用可分为两个阶段,分别由火山活动和构造运动主导成矿,并对应北祁连弧后区东段和西段的塞浦路斯型矿床。劳海盆中南部的扩张历史表现为由北向南逐渐开裂,北祁连弧后区蛇绿岩的年龄变化则指示自西向东的开裂过程。劳海盆南部热液区仍处于裂谷环境,具黑矿型矿床的特点,向北逐渐向塞浦路斯型过渡;北祁连弧后区虽以发育塞浦路斯型矿床为特征,但其东段邻近弧后区仍发育大量同时期的黑矿型矿床,表明了东段奥陶纪裂谷的发育。另外,Ba/Nb等比值指示劳海盆由南向北受俯冲消减的影响逐渐减小,北祁连弧后区则同现代劳海盆一样,且东段受俯冲消减作用的影响较西段更为明显,表明开裂时间越早,受俯冲消减的影响越小,反之则受俯冲消减的影响越大。这些都证明了劳海盆与北祁连弧后区的相似性。     

北祁连石居里地区Cu(Zn)-S矿床地质特征及综合成矿模式适

文章主要论述了北祁连山西段石居里矿田内Ⅵ号沟、Ⅷ号沟、九个泉等矿床的基本地质特征,并与北祁连山东段老虎山地区银硐沟、猪嘴哑吧等矿床对比.结合其早古生代构造演化历史、古洋脊或弧间、弧后拉张环境确定矿床类型,将上述3个矿床归属为蛇绿岩Cu(Zn)-S型矿床(类塞浦路斯型).建立综合成矿模式的基本要求(1) 矿床具有一定的时控性,有一定的含矿层位;(2) 生长性断裂的积极参与;(3) 海底火山喷发、喷气中心与次级盆地双向控制;(4) 多元热流体成矿系统.     

北祁连山早古生代弧后盆地火山作用及成矿特点——以肃南石居里沟富铜块状硫化物矿床为例

呈狭长带状分布于北祁连山走廊南山北坡的中—晚奥陶世弧后盆地海相火山岩,兼具洋中脊玄武岩和岛弧火山岩的特点。以基性火山岩为主,含有一定量的中性、中酸性火山岩;主要为熔岩,并有相当数量的火山碎屑岩。弧后盆地型火山岩发育的地段,即弧后扩张强烈的部位利于富铜（锌）型（塞浦路斯型）矿化,近来在甘肃省肃南石居里沟地区发现的富铜块状硫化物矿床为典型代表。矿体明显受火山机构制约的原生裂隙控制,矿化稍晚于火山作用,为海底热卤水（热液）对流循环成因。     

北祁连石居里地区Cu(Zn)-S矿床地质特征及综合成矿模式

文章主要论述了北祁连山西段石居里矿田内Ⅵ号沟、Ⅷ号沟、九个泉等矿床的基本地质特征，并与北祁连山东段老虎山地区银硐沟、猪嘴哑吧等矿床对比。结合其早古生代构造演化历史、古洋脊或弧间、弧后拉张环境确定矿床类型，将上述3个矿床归属为蛇绿岩Cu(Zn）－S型矿床（类塞浦路斯型）。建立综合成矿模式的基本要求：（1）矿床具有一定的时控性，有一定的含矿层位；（2）生长性断裂的积极参与；（3）海底火山喷发、喷气中心与次级盆地双向控制；（4）多元热流体成矿系统。     

Paleosubmarine Volcanism and Mineralization from North Qilian Mountains

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Geology, Geochemistry and Minerogenesis of the Shijuligou Zinc–Copper Deposit in Gansu, China

Abstract: The Shijuligou deposit was separated by an arcuate ductile shear zone cross the center of the deposit region, resulting in the difference between the southern and northern ore bodies. The lead (Pb) isotopic data of ores of the Shijuligou copper deposit have averages of 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb in 17.634, 15.444, and 37.312, respectively. It has been shown that ore-forming metals originated from intrusive and extrusive rocks in the upper part of ophiolites. The sulfur isotopic data of pyrite and chalcopyrite in the northern part change from +7.61‰ to +8.09‰ and +4.95‰ to +8.88‰ in the southern part. Isotopes of δ18O in the Shijuligou copper deposit are between +11.1‰ and +18.6‰, with the calculated δ18OH2O at +0.65‰. It is suggested that the mineralized fluid is a mixture of magma fluid, meteorological water, and seawater through circulating and leaching metals from the volcanic rocks. The zircon uranium-lead (U–Pb) dating of gabbro is 457.9±1.2 Ma, and the lower crossing age of the discordant and concordia curves of pyroxene spilite of zircon is 454±15 Ma. It is indicated that the Shijuligou deposit formed in a new ocean crust (ophiolite) of the back-arc basin in the late Ordovician. Mineralization should occur in the intermittence period after strong volcanic activity, and the age should be the late Ordovician. Moreover, the mineralization of ophiolite-hosted massive sulfide deposits in the ancient orogenic belt of the late Ordovician in the northern Qilian Mountains was controlled by the primary fault/fracture, with the forming of a metallogenic hydrothermal system by a mixture of volcanic magma fluid and seawater, which circularly leached the metallogenic metals from the volcanic rocks, resulting in their accumulation. The ore bodies were transformed with morphology and metallogenic elements. Jasperoid is an important sign for prospecting such deposits. There were many island arcs in the continent of China. This study provides evidence for understanding and exploration of ophiolite-hosted massive sulfide deposits in western China, especially in the area of northern Qilian Mountains.     

北祁连清水沟-白柳沟矿田块状硫化物矿床成矿特征及找矿方向

主要通过清水沟-白柳沟矿田与白银厂矿田的火山岩成分、微量元素特征成矿蚀变特征、地质特征等综合分析和对比研究,从块状硫化物矿床成矿系列角度,分析和讨论了清水沟-白柳沟矿田与典型的白银厂矿田的某些相似性或可比性,以期指出清水沟-自柳沟-带进一步找矿的潜力和远景地段。结果表明,2矿田无论是在成矿时代、赋矿岩石组合方面,还是在火山机构和成矿特征等方面皆有一定的可比性。由此提出在清水沟-白柳沟地区还有发现白银厂式块状硫化物矿床的潜力,并提出尕大坂是最具找矿潜力的远景区,值得进一步投人勘查工作。     

Chemical Composition of Ores from the Takara Volcanogenic Massive Sulfide Deposit, Central Japan

Abstract. The Takara volcanogenic massive sulfide (VMS) deposit occurs in Miocene formation of the Misaka Mountain, the South Fossa Magna region, central Japan. The tectonic setting of the Misaka Mountain is reconstructed to be a part of the paleo Izu-Ogasawara arc which collided with the Honshu arc and to form accreted body in the present position. The Takara deposit, therefore, is considered to have formed in the paleo Izu-Ogasawara arc.
The ores from the Takara deposit are classified into pyrite-type ore, chalcopyrite-type ore, and sphalerite-type ore on the basis of chemical composition and their mineral assemblages. Some pyrite-type ores are characterized by their high Au content. The Au content is hardly recognized in the chalcopyrite-type and sphalerite-type ores.
The ores from the Takara deposit have intermediate bulk chemical composition between those from the Besshi-type deposits and the Kuroko-type deposits that are two representative VMS deposits. However, the bulk chemical composition is closer to that from the Kuroko-type deposits. And moreover, chemical composition of tetrahedrite-tennantite series minerals (tetrahedrite) is similar to that from the Kuroko-type deposits. The bulk chemical composition (Cu, Zn, Co, Pb, and As contents) of ores is affected by the chemical composition of volcanic rocks associated with VMS deposits.     

东秦岭刘山岩块状硫化物矿床地质地球化学特征

刘山岩铜锌矿位于河南省桐柏县城北西25km的桐柏山北麓，处于东秦岭造山带之北秦岭褶皱带核部。矿体赋存于纹层状硅质-钠长石岩层中，矿石具纹层状、原生角砾状构造等，自矿体中心向边缘存在黄铁矿-黄铜矿-方铅矿-重晶石-石英的相对矿物分带。异常的浓度与组分分带反映的是一定时间域内成矿作用的延续与变化，纵向与轴向上具相同的组分分带，由中心至边缘的组分分带为Cd、Ge、Bi、As、Ga、Cu、Mo、Zn、Pb、Ag、Ba、Mn、V、W。根据异常元素组合、强度及其比值可以判断矿体剥蚀程度。重要的是，湿热条件下块状硫化物矿床赋矿岩系水系沉积物中成矿元素的贫化率极高，充分运用海底火山喷流相模式和圈定微弱、局部地球化学异常是勘查工作的根本手段。     

北祁连清水沟-白柳沟Fe-S和Pb-Zn-Cu型块状硫化物矿床形成环境探讨

青海祁连县清水沟—白柳沟新元古代寒武纪大陆裂谷双峰式海相火山岩中产有Fe-S和Pb-Zn-Cu型块状硫化物矿床.这两类矿床除受所在火山岩陆壳幔源区的部分熔融程度和火山作用旋回性不同影响外,主要受产生构造位置和火山岩浆源区物性条件所控制.其中产Fe-S型矿床的石头沟-香子沟穹窿火山作用,相对形成于近裂谷扩张中心的深海环境,以低K2O钙碱性的拉斑玄武质或英安质下地壳为物源区环境;郭米寺-白柳沟穹窿的Pb-Zn-Cu型火山作用形成于远离扩张中心的陆缘弧环境,源区为一种由地幔源和壳源共同构成的混合源.在矿床成因类型方面,前者近似塞浦路斯的铜黄铁矿,后者为较典型的日本黑矿型.