陕西双王钠长石岩特征及金矿床形成期次分析

双王含金钠长石岩带主要为层状 ,产于泥盆系星红铺组粉砂质板岩中。钠长石岩带主要由层状钠长石岩及钠长石岩角砾岩组成。角砾岩角砾主要为层状钠长石岩碎裂形成。层状钠长石岩及钠长石岩角砾韵律纹层构造及条带状构造发育 ,矿物组合和热水沉积钠长石岩相同。钠长石岩主元素及微量元素特征表明钠长石岩具热水沉积的一般特征。角砾岩角砾棱角明显 ,具可拼接破裂构造或典型角砾状构造 ;钠长石岩角砾和早期胶结物矿物组成基本相同。胶结充填物中晶洞构造发育 ,显示同生液压致裂角砾的一般特征。据钠长石岩沉积特征构造及角砾特征 ,认为钠长石岩及金矿床主要是热水沉积 -隐爆作用形成的 ,可分为 4个形成阶段 ,金矿矿化主要和第 3、4阶段有关。     

湘西合仁坪金矿床硫、铅同位素地球化学

湘西柳林汊一带广泛分布钠长石_石英脉型金矿,合仁坪金矿床是其典型代表。文章对合仁坪金矿床的硫、铅同位素进行了研究,并与区域石英脉型金矿床进行对比,探讨了该矿的成矿物质来源,并初步确定了其矿床成因。研究表明,合仁坪金矿床硫化物的δ34S值范围较窄(-4.8‰~4.4‰),平均为-0.6‰,该矿床的硫为深源硫,由深部变质流体带入;铅的同位素组成较均一,并表现出明显的造山带铅的特点。结合区域成矿作用,进一步研究揭示,合仁坪金矿床为一典型的造山型金矿,其成矿可能与湘西雪峰山地区加里东期的造山作用有关。     

湘中锡矿山矿区与成矿有关的角砾岩及其形成机制

湘中锡矿山锑矿床的角砾岩广泛发育,可以分为同生角砾岩、古岩溶角砾岩、断层角砾岩、液压致裂角砾岩等类型。本文主要对与成矿有关的角砾岩进行了深入研究,在详细的野外调研与定性研究基础上,应用分形几何的定量描述方法,确定了其角砾颗粒大小分布维数D_s和形态分布维数D_r以及D_l等参数,并在此基础上,探讨了该区角砾岩的形成机制。研究表明,与矿有关的角砾岩主要可分为两类:方解石胶结的角砾岩和硅质胶结的角砾岩;含矿方解石胶结弱硅化灰岩角砾主要为液压致裂的物理成因,而含矿硅质胶结的强硅化灰岩角砾既有物理致裂作用,又伴有热液参与的化学溶蚀作用;液压致裂是锡矿山矿区角砾岩形成的重要机制。     

西秦岭地区大桥金矿床硅化角砾岩的特征及成因

大桥金矿床是西秦岭地区近年来新发现的一种金矿床类型。矿体赋存在三叠系与石炭系不整合面附近和三叠系内层间滑脱构造中,与硅化角砾岩的关系非常密切,矿化及角砾岩化自不整合面或层间滑脱构造向两侧围岩逐渐减弱。硅化角砾岩体由不同的角砾岩层构成,其产状总体轻微切层,沿走向延伸稳定;角砾主要为遭受不同程度硅化的板岩、灰岩和方解石等,杂基为原地的粉砂屑和断层泥,胶结物为细脉浸染状含金硫化物、微晶石英、玉髓和方解石等。野外观察和岩相学研究表明,大桥金矿区的硅化角砾岩是在早期构造角砾岩遭受强烈硅化的基础上进一步经过多期液压致裂作用形成的,多期次的硅化、液压致裂及自愈合作用导致角砾岩中大量含金硫化物的卸载沉淀。对西秦岭造山带的区域构造分析表明,在与碰撞造山逆冲推覆及随后的板内演化相关的区域变质变形过程中,大规模深部变质热液在压力和热梯度的驱使下沿区域深大断裂上升,多次脉冲式进入地层不整合面及层间滑脱构造中导致岩石发生强烈硅化,进而发生液压致裂作用而形成复杂的含金角砾岩。     

隐爆角砾岩型金矿床成矿特征浅析--以山西堡子湾、河南祁雨沟金矿床为例

中酸性岩浆侵入体隐蔽爆破作用形成角砾岩体(筒)的同时于其中形成隐爆角砾岩型金矿床.侵入岩体规模一般较小,岩性主要为闪长岩类、石英(二长)斑岩类或正长岩类的中酸性岩石.角砾岩体在平面上呈近圆形或椭圆形,面积相对较小,在剖面上呈垂直地表的筒状,深部一般与中酸性侵入岩体相连.角砾的成分在浅部多为围岩角砾,往深部逐渐变为以花岗质角砾为主,胶结物主要是细岩屑和蚀变矿物.中酸性侵入体是矿床的成矿母岩,隐爆作用的发生及形成的隐爆角砾岩体(筒)是容矿构造,角砾岩体中的次级断裂是控矿构造,各因素对于此类型金矿床的形成起着重要的作用.     

黑龙江金厂金矿床流体包裹体特征及成矿作用研究

金厂金矿床是一个发育有隐爆角砾岩筒、似层状微细脉浸染及裂控石英脉-蚀变岩三种矿化类型的特大规模矿床。本文对区内三类矿化石英中的流体包裹体进行了岩相学、显微测温、成分、氢-氧同位素及子矿物的扫描电镜等多方面对比研究,结果表明三类矿化成矿流体具有不同的地球化学性质:隐爆角砾岩筒成矿流体为岩浆-溶液过渡态流体;似层状微细脉浸染型成矿流体为一种成分复杂的高盐度热液;而裂控型成矿流体为高盐度的NaCl-H₂O溶液。氢-氧同位素组成特征揭示出它们均来自于岩浆活动。结合矿体产状及已有的年代学资料,认为三类矿化形成顺序为隐爆角砾岩筒型→似层状微细脉浸染型→裂控型,因此金厂金矿床是不同期次岩浆来源流体叠加成矿的产物。     

陕西桐木沟锌矿床中沉积喷气成矿作用的早期产物——钠长角砾岩

钠长角砾岩以整合的层状产于层状矿体的下伏地层中。角砾来源于下伏地层,主要为石英钠长石岩,呈无分选、磨圆差的混杂堆积。胶结物主要矿物成分为铁白云石和钠长石,中粗粒花岗变晶结构。胶结物的稀土元素组成具有低∑REE,低LREE/HREE的特点,C—O同位素组成指示其形成于较高的温度环境,岩组分析表明其与正常的沉积地层经历了相同的变形史。因此,钠长角砾岩是喷气热液同生沉积形成的,是成矿地热系统早期活动的产物,可作为在秦岭寻找同类矿床的找矿标志。     

铜陵凤凰山铜矿床角砾岩的形成与矿床定位机制

角砾岩不仅记录了矿区构造的形成演化过程,同时也记录了矿床的形成定位过程,因此对角砾岩的产出、分布特征研究有利于进一步揭示矿床的形成与定位机制.凤凰山铜矿区不同类型角砾岩的分形研究结果表明,该区角砾状花岗闪长岩属于化学成因角砾岩,在形成过程中有物理作用的参与,而角砾状矿石和角砾状大理岩是水力致裂角砾岩,形成时能量达到中等,说明该区角砾岩的形成与成矿热液的演化密切相关.     

河南祁雨沟热液角砾岩体型矿床成硫流体研究

祁雨沟金矿床产于燕山期热液角砾岩筒内,通过对４号角砾岩体胶结物和石英－碳酸盐胶内流体包裹体研究表明,其中的包裹体类型非常复杂,有气体包裹体,气液包裹体,液体所裹体,含子矿物高盐裹体和含ＣＯ２包裹体五种类型,成矿的初始热液为高温高盐流体,它们来源于燕山期花岗岩浆热液,由于角砾岩体的隐爆,流体减压沸腾及古大气水的混入,热液中的金被沉淀成矿,形成胶结物型和脉型金矿化,金矿的开始成矿于温度较高（３１０～３     

秦岭造山带二台子铜金矿床矿物地球化学研究

通过矿物地示化学研究,认为陕西二台子铜金矿床属钠长石碳酸角砾岩型矿床,是大陆热点成矿系统中幔源碱性热流体成岩成矿作用多期叠架所形成。砷黝铜矿富Ｆｅ、Ａｓ,低Ｓｂ、Ａｇ;黄铁矿中富Ａｓ、Ｓｅ,白云石（内核）有显著的锰铁白云石（外部环带）增生环带;长石类矿物出现富Ｍｇ铁长石;这些特征是陕西二台子铜金矿床属钠长石碳酸角砾岩型矿床的典型矿物地球化学特征。矿物地球化学组合类型指标可判断不同矿化类型及分散矿化     

http://www.sciencedirect.com/science/article/pii/S1674987111000764

The Jinding Zn-Pb deposit has been generally considered to have formed from circulating basinal fluids in a relatively passive way,with fluid flow being controlled by structures and sedimentary facies,similar to many other sediments-hosted base metal deposits.However,several recent studies have revealed the presence of sand injection structures,intrusive breccias,and hydraulic fractures in the open pit of the Jinding deposit and suggested that the deposit was formed from explosive release of overpres-sured fluids.This study reports new observations of fluid overpressure-related structures from underground workings(Paomaping and Fengzishan).which show clearer crosscutting relationships than in the open pit.The observed structures include:I) sand(±rock fragment) dikes injecting into fractures in solidified rocks:2) sand(±rock fragment) bodies intruding into unconsolidated or semi-consolidated sediments;3) disintegrated semi-consolidated sand bodies;and 4) veins and breccias formed from hydraulic fracturing of solidified rocks followed by cementation of hydrothermal minerals.The development of ore minerals(sphalerite) in the cement of the various clastic injection and hydraulic fractures indicate that these structures were formed at the same time as mineralization.The development of hydraulic fractures and breccias with random orientation indicates small differential stress during mineralization,which is different from the stress field with strong horizontal shortening prior to mineralization. Fluid flow velocity may have been up to more than 11 m/s based on calculations from the size of the fragments in the clastic dikes.The clastic injection and hydraulic fracturing structures are interpreted to have formed from explosive release of overpressured fluids,which may have been related to either magmatic intrusions at depth or seismic activities that episodically tapped an overpressured fluid reservoir.Because the clastic injection and hydraulic structures are genetically linked with the mineralizing fluid source,they can be used as a guide for mineral exploration.     

马来西亚沙捞越邦达、什兰江控矿角砾岩筒构造对比研究及其找矿意义

马来西亚沙捞越邦达、什兰江控矿角砾岩筒构造均为典型的浅成—半浅成角砾岩筒构造，角砾岩及控矿类型具有明显的垂向分带特点。邦达控矿角砾岩筒构造发育角砾岩筒上段的塌陷角砾岩，角砾岩筒剥蚀深度较浅，控制典型的高硫化型浅成低温金铜矿床，且其深部具有较大的找矿潜力。什兰江控矿角砾岩筒构造发育角砾岩筒下段的爆发角砾岩和中段的流化角砾岩，分别控制斑岩型金矿化和低硫化型浅成低温热液型金矿化，角砾岩筒剥蚀深度较大，对矿床的保存和找矿极为不利。     

新疆伊犁京希-伊尔曼德金矿区角砾岩特征及成因

京希－伊尔曼德金矿化区内发育有大量似层状产出的角砾岩，研究认为它们是与热液流体直接相关的水力致裂角砾岩，空间上沿不整合面之上覆粗碎屑岩层产出，角砾岩化的过程为：深源热流体在压力和热梯度的驱使下沿陡倾断层上升，当其到达孔隙度发育的粗碎屑岩层时，热流体转为侧向顺层侵入并使围岩发生角砾岩化，形成热液角砾岩。角砾岩特征的分形分析表明，角砾岩化的形成作用以物理－机械破碎作用为主，能量中等。金矿化与角砾岩化强度及空间分布密切相关。     

甘肃洛坝铅锌矿床的构造控矿作用

甘肃洛坝铅锌矿床矿体形态复杂,长期存在"背斜控矿"与"单斜控矿"的争论.矿体及赋矿岩石夹持于区域性的黄渚关断裂与江洛-人土山断裂间,两断裂在矿区相距不足1 km,矿床整体处于其间的断裂破碎带中.层状矿体形成后遭受了强烈的构造挤压变形改造,相当一部分"千枚岩"为强挤压的断层岩,其中含有灰岩及矿石角砾.矿体不再是简单的"秦岭型"铅锌矿的背斜控矿或单斜控矿,而是受控于断裂破碎带.对矿区控矿断裂的研究将有助于已知矿体的开采和深部与外围地区盲矿的勘探.     

句容甲山膨润土矿的地质特征和成因探讨

研究了句容甲山膨润土矿的矿床地质特征,发现地层上覆下白垩统碱性流纹岩,矿石呈黄绿色、粉红色、灰白色和肉红色等多种颜色,局部保留有原岩的角砾结构,并观察到含有风化残余的粗面岩团块和因断层滑移形成的断层角砾。X射线衍射（XRD）分析发现不同颜色矿石的矿物组成差异很大,通过扫描电子显微镜观察到岩石风化现象和伴生的次生矿物类型。研究表明,该矿属于火山熔岩风化残积型膨润土矿床,在开发过程中应进行分类开发或进行深加工处理,可提高开发效益。     

Origin of a large breccia-vein system in the Sanerlin uranium deposit, southern China: a reinterpretation

The early Tertiary Sanerlin uranium deposit is located near the southwestern margin of the Chaling-Yongxing pull-apart basin defined by the Chaling-Yongxing and Chenxian-Linwu sinistral strike-slip faults in southern China. The uranium ores are hosted in 15 breccia-vein bodies, which are separately located in the cores of three secondary anticlines of the Upper Permian Dangchong Formation. Individual breccia-vein bodies are composed of fragments of silicified shale and sandstone from the Dangchong Formation, and quartz veinlets as cements. These fragments, together with quartz veins, form a mosaic texture. Hydrothermal pitchblende is the only commercial uranium mineral, mainly occurring as disseminated grains within quartz veins or coating fragments. Other metallic minerals include molybdenite, pyrite, chalcopyrite, galena, sphalerite, and red microcrystalline hematite. Fluid inclusions in quartz veins have homogenization temperatures ranging from 150 to 280 °C, and calculated salinity values between 5.6 and 13.4 wt% NaCl equivalent. Stable isotope analyses show that the mineralizing fluid was characterized by '¹⁸O values of -2.2 to +2.6‰ and 'D_H2O values of -134 to -110‰. These analytical data demonstrate that hydrothermal fluids were mainly derived from formation waters (brines) of the Chaling-Yongxing basin. Fluid overpressuring was caused by an abnormal geothermal gradient and impermeable shales in the deposit area. The geometry, texture, and structure of the breccia-vein system, along with the fluid pressure estimates, suggest that hydraulic fracturing generated the mineralized breccia-vein system. Pitchblende and associated minerals were deposited when gaseous phases were released abruptly from the ore fluids due to the hydraulic fracturing.     

FORMATION CONDITIONS AND DISTINCTIVE FEATURES OF TECTONIC BRECCIAS IN THE KARATAU RANGE,MIDDLE PALEOZOIC CARBONATE SECTION (SOUTH KAZAKHSTAN)

This paper reviews ideas regarding origin and classification of carbonate breccias in the middle Paleozoic section of the Karatau Range. A genetic classification of these breccias, following that of T. M. Dembo, is based on the following important criteria: 1) stratigraphic nature of component fragments; 2) contact relations with enclosing strata; 3) character of lateral changes of breccias; 4) nature of interfragmental matrix and cement; 5) degree of replacement and recrystallization. Breccias are grouped into the following five principal types, within each of which there may be distinguished several subtypes:

1. I - Cumulative

   II - Sedimentary-deformational
   III - Tectonic
   IV - Polygenetic
   V - Karst

The carbonate breccias of the Karatau Range include a number of distinct tectonic varieties which are discussed in some detail. --R.C. Epis.     

Petrology, chemistry and origin of Apollo 15 regolith breccias

Variations in modal petrology, mineral compositions and bulk compositions were determined for ten Apollo 15 regolith breccias for comparison with local soils and assessment of the intrasite petrologic variability of the Apollo 15 regolith. Based on the above criteria the breccias are of local origin and mimic the soils from the corresponding sampling stations, with the exception of station 2 breccia 15205. This sample formed from an anomalous regolith and although not considered exotic to the site is not representative of the soil at the site. KREEP basalt and green glass components vary from trace amounts to dominant in the breccias, evidence that these materials entered the regolith prior to formation of the breccias. Breccias from the edge of Hadley Rille are modally richer in highland fragments than the soils, whereas at the base of Hadley Delta the reverse is true. This is explained by the loss of material into the Rille to be replaced by basalt-derived material, making the soils more basalt-rich. At the base of Hadley Delta highland material is accumulating and the soils are becoming more highland-rich. Over billions of years these processes have developed differences between the present day, evolving soils and “fossil” non-evolving soils represented by the regolith breccias. This shows that there has been little change in the geology and the morphology of the Apollo 15 site, probably since the eruption of mare basalts at the site (˜3.3 b.y.).     

陕西双王金矿床角砾岩动力学成因探讨

双王金矿可拼性含金角砾岩是流体致裂角砾岩,而不是构造角砾岩或隐爆角砾岩。该区的深源异常高压流体是角砾岩产生的必要条件。角砾岩的动力学成因主要是区域变质作用、地壳隆升剥蚀作用和地下岩浆活动等形成异常高压流体,在重力、浮力和地热梯度的驱动下,在能干性强的岩石中产生裂隙,并向浅部增殖,被碳酸盐矿物等充填胶结。周而复始的流体压裂—沉淀愈合作用,使金多次富集,形成矿体。     

Structural controls and genesis of epithermal gold-bearing breccias at the Lebong Tandai mine, Western Sumatra, Indonesia

Lebong Tandai is a low-sulphidation, volcanic-hosted epithermal gold deposit of Neogene age, located within the foothills of the Barisan Mountains, Sumatra. To date, the mine has produced approximately 40 tonnes of gold and 400 tonnes of silver. The mineralisation is exclusively in the form of tabular quartz-cemented breccias bodies which are localised along faults. The breccias comprise angular to sub-rounded clasts of the wallrocks and earlier barren breccias cemented by banded or massive quartz, and in many instances, the clasts are supported within the quartz cement.The sulphide minerals occur as either a single cockade band around the clasts in the breccia, or as polymineralic aggregates disseminated throughout the breccia cement. The main precious-metal-bearing phase is electrum, with silver-sulphosalts and silver-tellurides also present. Highly variable concentrations of pyrite, sphalerite, galena and chalcopyrite are associated with the precious-metal phases.With the exception of two minor lodes, the mineralised breccias are localised along strike-slip faults which display changes in orientation indicative of D-, R- and P-shears and T-fractures, with individual segments ranging from a few metres to a few hundred metres in length. Two strike-slip fault systems are recognised, one sinistral, trending east-west and the other dextral, trending northwest, the latter of which is parallel to the Sumatran Fault System. The majority of gold and silver production is from breccias localised along faults formed during the sinistral tectonism. The breccias are believed to have been generated during compressional reactivation of the east-west sinistral strike-slip faults in response to the subduction of the Indian-Australian plate beneath Sumatra. Supralithostatic fluid pressures are a necessary pre-requisite for such reactivation, and the sudden drop in fluid pressure during reactivation is thought to have resulted in both the formation of the breccias by hydraulic fracturing, and the deposition of amorphous silica, precious metals and base metal sulphides. High rates of fluid flow subsequent to fracturing are thought to have led to fluidisation of the breccia clasts and abrasion to their current morphologies.Microthermometry of fluid inclusions in sphalerite indicates that the mineralising fluids were of low salinity, less than 3 wt% NaCl_equivalent, and that mineralisation took place at temperatures of 260–280°C. Variations of salinity and homogenisation temperature due to boiling are poorly developed, although if boiling occurred, the metalliferous minerals would have been deposited early in the boiling process before the fluid had cooled appreciably.