内蒙古北山额勒根乌兰乌拉一带土壤测量地球化学特征及找矿方向

研究区位于内蒙古北山北带,成矿地质条件优越,1∶20万水系沉积物测量异常明显,且分布有额勒根乌兰乌拉斑岩型钼(铜)矿。以1∶5万土壤地球化学测量成果为依据,以地质认识为基础,研究了区内元素地球化学数据特征、地球化学场特征及综合异常特征。认为区内主成矿元素为Mo、Cu、Au,主要的控矿层位为咸水湖组火山岩段,成矿有利侵入体为石炭纪花岗闪长岩。划分出5种综合异常类型,其中与斑岩钼(铜)矿系统有关的综合异常和与奥陶系建造有关的综合异常是今后解剖找矿的重点。     

The Batu Hijau porphyry copper-gold deposit, Sumbawa Island, Indonesia

The Batu Hijau porphyry Cu---Au deposit lies in southwest Sumbawa Island, Indonesia. It is a world-class porphyry Cu deposit in an island are setting, and is typical of this deposit type in most features, including igneous association, morphology, hydrothermal alteration and mineralisation style.The region was not previously recognised as a porphyry Cu province; disseminated Cu sulphides were first recognised in float samples in southwest Sumbawa in 1987. Associated stream sediment sampling identified a broad area of anomalous Au and Cu in an area of greater than 5 km² around Batu Hijau, including 169 ppb Au in BLEG samples and 580 ppm Cu in stream silts 1 km from the deposit. Mineralisation in bedrock at surface contains > 0.1 wt % Cu and > 0.1 ppm Au over an area of 0.6 km × 1.2 km, including a zone 300 m × 900 m containing > 0.3 wt % Cu. Areas with elevated Mo (> 30 ppm) form a distinctive annulus around this Cu-rich zone.Batu Hijau mineralisation is hosted in a tonalite intrusive complex, and diorite and metavolcanic wallrocks. There are no post-mineralisation igneous intrusions or breccia pipes within the deposit. The main tonalite intrusion forms a stock in the centre of the deposit, where it generally displays intensely pervasive potassic (biotite with magnetite-quartz) alteration and hosts most of the higher grade mineralisation. Younger tonalite dykes intruding the centre of this stock are generally less altered and mineralised than the older tonalite.The core zone of potassic alteration grades outward into extensive propylitic alteration (chlorite-epidote), with both variably overprinted by widespread fracture controlled intermediate argillic alteration (sericite-chlorite), and minor phyllic (sericite-pyrite) and sodic (albite) alteration. Argillic (sericite-kaolinite) and advanced argillic (kaolinite-alunite-pyrophyllite) assemblages occur near surface.Copper and Au grades within the orebody show a positive correlation with quartz stockwork intensity, although disseminated Cu sulphides are also common. Chalcopyrite and bornite are the principle hypogenal minerals, with minor chalcocite. Oxidation extends to a depth of 5 m to 85 m below surface across the deposit, and is underlain by weak supergene mineralisation. Drill testing of the deposit down to 650 m below surface reveals a single cylindrical to conical orebody of 334 million tonnes grading 0.8 wt % Cu and 0.69 gm per tonne Au; the depth extent of mineralisation is unknown.     

Discovery and exploration of the Gosowong epithermal gold deposit, Halmahera, Indonesia

The Gosowong epithermal gold deposit, on the island of Halmahera in eastern Indonesia, is located in an area of primary tropical rain forest with no previous history of gold mining or record of gold mineralisation. The deposit occurs in a newly recognised mineral district which contains a number of epithermal vein systems and at least two centres of low-grade porphyry style Cu–Au mineralisation. Several zones of argillic and advanced argillic alteration have been noted which may be related to additional centres of mineralisation. Gosowong is classified as a low-sulphidation epithermal quartz vein. Bonanza-grade gold–silver mineralisation is developed in shoots over a 400-m strike section of the vein system. Three types of veining are recognized; quartz–adularia veins and breccias; quartz–chlorite–illite veins and breccias; and crystalline or chalcedonic quartz vein stockworks. The area was targetted using a simple geological concept and the deposit was discovered and tested using basic exploration techniques commonly applied in the rugged tropical terrains of Indonesia. Sequential exploration methods comprised reconnaissance drainage sampling of stream sediment, BLEG and float media, ridge and spur soil sampling, prospect scale grid soil sampling, hand trenching and diamond drilling. Lapse time from identification of the initial reconnaissance anomaly to an inferred resource estimate of almost 1 million ounces of gold was less than 3.5 years. This case history illustrates that very detailed exploration is necessary to locate high-grade vein-type gold deposits in a tropical environment, but demonstrates that such resources still remain to be discovered in the relatively under-explored Neogene magmatic arcs of Indonesia.     

Recognition of geochemical footprints of mineral systems in the regolith at regional to continental scales

Understanding the character of Australia's extensive regolith cover is crucial to the continuing success of mineral exploration. We hypothesise that the regolith contains geochemical fingerprints of processes related to the development and preservation of mineral systems at a range of scales. We test this hypothesis by analysing the composition of surface sediments within greenfield regional-scale (southern Thomson Orogen) and continental-scale (Australia) study areas. In the southern Thomson Orogen area, the first principal component (PC1) derived in our study [Ca, Sr, Cu, Mg, Au and Mo at one end; rare earth elements (REEs) and Th at the other] is very similar to the empirical vector used by a local company (enrichment in Sr, Ca and Au concomitant with depletion in REEs) to successfully site exploration drill holes for Cu–Au mineralisation. Mapping of the spatial distribution of PC1 in the region reveals several areas of elevated values and possible mineralisation potential. One of the strongest targets in the PC1 map is located between Brewarrina and Bourke in northern New South Wales. Here, exploration drilling has intersected porphyry Cu–Au mineralisation with up to 1 wt% Cu, 0.1 g/t Au, and 717 ppm Zn. The analysis of a comparable geochemical dataset at the continental scale yields a compositionally similar PC1 (Ca, Sr, Mg, Cu, Au and Mo at one end; REEs and Th at the other) to that of the regional study. Mapping PC1 at the continental scale shows patterns that (1) are spatially compatible with the regional study and (2) reveal several geological regions of elevated values, possibly suggesting an enhanced potential for porphyry Cu–Au mineralisation. These include well-endowed mineral provinces such as the Curnamona and Capricorn regions, but also some greenfield regions such as the Albany-Fraser/western Eucla, western Murray and Eromanga geological regions. We conclude that the geochemical composition of Australia's regolith may hold critical information pertaining to mineralisation within/beneath it.     

西藏改则县多不杂斑岩型铜金矿床勘查模型

西藏改则县多不杂斑岩型铜金矿床是近年来由西藏地质五队在班公湖-怒江成矿带发现的一个具超大型规模的铜金矿床,系继玉龙、驱龙、雄村、甲玛等超大型铜矿床之后的又一重大找矿突破,也是班公湖-怒江成矿带的第一个超大型斑岩铜金矿。多不杂斑岩型铜金矿产于早白垩世花岗闪长斑岩及其与早侏罗世曲色组变长石石英砂岩的接触带,区域成矿地质背景得天独厚,岩浆活动频繁,为斑岩型铜金矿的成矿提供了有利的条件。该矿床具有典型的斑岩型铜矿的蚀变分带,在斑岩体及其围岩由内向外形成钾硅化带、粘土化带、青磐岩化带、角岩化带。地球物理勘查表明,含矿斑岩区为低视电阻率、高视极化率异常区;1:1万土壤测量显示,斑岩铜矿产于高背景区,并与强度高、浓集中心明显的Cu、Au、Ag、Mo元素的化探综合异常相对应,在空间上尤其与Cu、Au异常分布高度吻合。1:5万水系沉积物测量表明,Au、Ag、As、Sb、Cu、Pb、Zn元素高异常常与激电探测异常吻合。本文通过综合研究初步总结建立了适合本区地质-地球物理-地球化学综合勘查模型。通过勘查和初步评价,在矿区外围新发现了波龙、拿顿、拿若、赛角、尕尔勤、铁格龙、地堡那木岗等斑岩矿(床)点,并最终形成多龙斑岩型铜金矿集区,对该区域找矿起到指导作用。     

斑岩型铜、金、钼矿床成岩成矿特征差异的原因和意义

文中简要总结了斑岩型金矿、铜矿和钼矿在产出的构造环境,岩石地球化学特征和出溶流体的温度、压力、盐度、蚀变等方面的异同点,重点从元素的地球化学性质、岩浆的源区和过程(熔体和流体演化)3个方面解释了上述差异。Au、Cu和Mo在地球化学性质尤其是亲硫性上的差异决定了元素在不同的大地构造环境下的岩浆作用过程中的分布、迁移和富集特征,最终控制了矿床的分布。岩浆的源区及其温压条件、熔体上升过程中矿物的分离结晶和中上地壳岩浆房内的演化程度控制了成矿岩浆的地球化学特征,进而影响其就位时的压力和温度,从而导致出溶流体在p-T-X上的变化。结合岩浆岩中大离子亲石元素和SiO2的含量,可以评估斑岩型矿床的类型：高的Rb含量是斑岩型钼矿的特征,高的Ba含量是斑岩型钼+铜矿的特征,高的Sr含量是斑岩型铜+金矿的特征。相对于俯冲环境,后俯冲环境下的成矿岩体具有更高的大离子亲石元素含量。矿区中酸性岩石的结构(斑状、似斑状、不等粒和等粒结构)可以用来初步指示成矿的潜力。     

黑龙江省某地区地球化学异常、地质特征及成矿预测

在黑龙江某地区1:5万水系沉积物测量的基础上,对测区内可能富集成矿的Bi、Cu、Hg、W、As、Au、Mo、Zn、Sb、Ag、Pb等元素地球化学特征进行了系统阐述,其中极有可能成矿的元素是Bi、Hg、Cu、Zn、W、Mo。     

化探在金龙山金矿勘查中的应用

金龙山金矿是化探与地质普查相结合的方法找到的.先采用水系沉积物测量圈出异常,然后进行土壤(岩石)测量缩小靶区,最后进行地质普查,发现金矿(化)体.对岩石地球化学异常进行定量分析后,认为金龙山矿区及其外围找矿潜力巨大.     

Regional geochemical reconnaissance of the Cordillera Occidental of Ecuador: economic and environmental applications

A regional geochemical reconnaissance survey of the Cordillera Occidental of Ecuador was initiated in 1995 as a sub-component of a wider Mining Development and Environmental Control Technical Assistance Project (PRODEMINCA) in Ecuador. The 36,000 km² survey area encompasses oceanic and continental-margin volcano-sedimentary terranes with known occurrences of porphyry-style Cu-Mo, exhalative massive sulphide, epithermal Au and mesothermal polymetallic mineralisation. A survey sample medium of <177 μm stream sediments was selected following an orientation study in the vicinity of known porphyry Cu mineralisation. In the 2–4°S sector of the Cordillera Occidental for which data are presented, 4850 drainage samples were collected at an average density of 1 per 2.57 km². All were analysed for 36 major and trace elements (Au, Ag, Cu, Pb, Zn, Mo, Ni, Co, Cd, Bi, As, Sb, Fe, Hg, Mn, Te, Ba, Cr, V, Sn, W, La, Al, Mg, Ca, Na, K, Sr, Y, Ga, Li, Nb, Sc, Ta, Ti, Zr). A stringent quality-control procedure included the systematic analysis of certified reference samples, field duplicates and replicates, data for which were used to calculate analytical precision, temporal drift and practical detection limits. Results for this part of the cordillera highlight the contrasting lithogeochemical signatures of the ocean-floor basalt terrane (Pallatanga Unit), the island-arc terrane of the Macuchi Unit, the continental volcanics of the Saraguro Group and the acid and intermediate lavas extruded from the Late Miocene to the Quaternary. Regional geochemical images for Au and associated pathfinder elements are dominated by anomalies relating to known mines and prospects. New exploration targets, often inconspicuous at the regional scale, have however been identified through the normalisation of data for individual lithological units against their respective geochemical backgrounds. In addition to mineral exploration, the drainage geochemical dataset for the Cordillera Occidental provides an unparalleled environmental baseline against which the impacts of future anthropogenic activities (including mining) may be assessed. A basis for the formulation of pragmatic sediment quality criteria and for the identification of natural geochemical hazards is also provided.     

Comparison of U-spatial statistics and C–A fractal models for delineating anomaly patterns of porphyry-type Cu geochemical signatures in the Varzaghan district,NW Iran

The delineation of populations of stream sediment geochemical data is a crucial task in regional exploration surveys. In this contribution, uni-element stream sediment geochemical data of Cu, Au, Mo, and Bi have been subjected to two reliable anomaly-background separation methods, namely, the concentration-area (C–A) fractal and the U-spatial statistics methods to separate geochemical anomalies related to porphyry-type Cu mineralization in northwest Iran. The quantitative comparison of the delineated geochemical populations using the modified success-rate curves revealed the superiority of the U-spatial statistics method over the fractal model. Moreover, geochemical maps of investigated elements revealed strongly positive correlations between strong anomalies and Oligocene–Miocene intrusions in the study area. Therefore, follow-up exploration programs should focus on these areas.     

Stream sediment geochemical exploration for gold in Central Eastern Desert,Egypt: Application of the concentration-number fractal model,factor analysis,and geochemical mineralization probability index

Geochemical exploration by stream sediment sampling using bulk leach extractable gold (BLEG) technique and applying concentration-number (C-N) fractal model, factor analysis (FA), and geochemical mineralization probability index (GMPI) resulted in the recognition of new Au occurrences around the Sukari gold mine in the central Eastern Desert of Egypt. The geochemical data of 128 stream sediment samples collected from the study area was used for delineating the geochemical anomalies and characterizing the dispersion trains of ore and associated elements (Au, Ag, As, Sb, Cu, Pb, Zn, Mo). Statistical analysis of the geochemical data applying the C-N fractal modeling enabled us to identify significant anomaly and background populations of the investigated elements and to construct reliable geochemical anomaly maps. Factor analysis using centered log-ratios (CLR), to address the problem of closed compositional data, revealed significant element associations for mineralization (Au, As, Mo, Zn, Ba), country rock compositions (Rb, Li, Be, Sn, Bi for granite, and Co, Cr, Ni for mafic rocks), and element mobility (e.g. Sb, Zr, and Ag). Weak and moderate Au anomalies that cannot be detected by factor score maps can be delineated clearly by using the C-N fractal method and GMPI distribution map. Our study revealed that Ag, As, and Sb are the main pathfinder elements for gold mineralization in arid to semiarid regions exemplified by the Sukari gold district. Silver can be used as a “direct” pathfinder, whereas As and Sb are “indirect” pathfinders for Au in such regions. The spatial distribution of Au and Ag anomalies indicate that gold mineralization in the Sukari district is structurally controlled. However, the spatial distribution of Cu, Pb, Zn, and Mo is controlled by mineralogical and lithological factors and is not related to any significant base metal deposits.     

The behavior of ore elements in oxidized heterophase chloride and carbonate–chloride–sulfate fluids of porphyry Cu–Mo(Au) deposits (from experimental data)

The spatial coexistence and synchronous formation of magmatogene porphyry Cu–Mo mineralization and epithermal gold mineralization are due to the genetic relationship between their formation processes. This relationship might be due to the generation of metal-bearing fluids of different geochemical compositions by the porphyry ore-magmatic system, which then participate in the formation of magmatogene porphyry Cu–Mo(Au) and associated epithermal gold deposits. Synthesis of fluid inclusions in quartz was performed for experimental study of the behavior of Cu, Mo, W, Sn, Au, As, Sb, Te, Ag, and Bi in heterophase fluids similar in composition and aggregate state to natural ore-forming fluids of porphyry Cu–Mo(Au) deposits. We have established that at 700 °C, a pressure decrease from 117 to 106 MPa leads to a significant enrichment of the gas phase of heterophase chloride fluid with Au, As, Sb, and Bi. The heterophase state of carbonate–chloride–sulfate fluids is observed at 600 °C and 100–90 MPa. It characterizes the highly concentrated liquid carbonate–sulfide phase–liquid chloride phase–low-density gas phase equilibrium. A decrease in the pressure of heterophase carbonate–chloride–sulfate fluid leads to a noticeable enrichment of its chloride phase with Cu, Mo, Fe, W, Ag, Sn, Sb, and Zn relative to the carbonate–sulfate phase. The processes of redistribution of ore elements between the phases of heterophase fluids can be considered a model of generation of metal-bearing chloride fluids, which occurs in nature during the formation of porphyry Cu–Mo(Au) deposits, as well as a model of generation of gas fluids supplying Au, Te, As, and other ore elements to the place of formation of epithermal Au–Cu and Au–Ag mineralization.© 2015, V.S. Sobolev IGM, Siberian Branch of the RAS. Published by Elsevier B.V. All rights reserved.     

Comparison of vegetation and stream sediment geochemical patterns in northeastern New South Wales

This study compares the geochemical response of stream sediments and adjacent vegetation samples, with variations in drainage catchment lithology and the occurrence of mineralisation, within a 14,000-km² block of the northeastern region of New South Wales, Australia. The area contains a range of lithologies within a Devonian–Permian accretionary complex and Mesozoic sedimentary basin, as well as a wide range of mineral deposits. Sampling was designed to confine each sub-catchment to a single lithological group (mafic and ultramafic rocks, acid intrusives, volcanics, metasedimentary and sedimentary rocks or alluvium). Leaves of over 20 genera, dominated by (Allo-)Casuarina, Eucalyptus, Acacia, Callistemon and Melaleuca, and the <250-μm fraction of the stream sediments were analysed by INAA. The uptake of most trace elements varied between genera, with Callistemon displaying the highest median As and La contents and Eucalyptus the highest Co contents. The stream sediment and vegetation geochemistry reflect both hydromorphic and mechanical dispersion within sub-catchments, with regional patterns dominant over local influences. The vegetation appears to be influenced to a greater extent by hydromorphic dispersion, as indicated by differences in the ratio of leaf to sediment Cr concentrations in sub-catchments draining serpentinites and basalts. Although most known mineral deposits in the region produced anomalies in at least one medium, there was little correlation between the trace element concentrations of the vegetation and stream sediments on a site-by-site basis. A number of Au targets were only detected on the basis of the biogeochemistry and others were only reflected in the stream sediment geochemistry. In general, vegetation displayed more extensive dispersion trains away from mineralisation than did the stream sediments. Differences in the response of the two sampling media suggest their joint use in exploration or environmental surveys to maximise the probability of detecting mineralisation.     

The Bolcana Cu–Au ore deposit (Metaliferi Mountains,Romania): first data on the alteration and related mineralisation

The Bolcana ore deposit (Metaliferi Mountains, western Romania) is a porphyry ore deposit with associated epithermal veins. On the basis of different parageneses, four alteration types were distinguished: potassic, phyllic, argillic and propylitic. The mineralogical and geochemical data and estimated crystallisation temperatures of alteration minerals indicate an evolution of the system from an early period of porphyry type mineralisation (Cu+Au) to a late period of low-sulphidation epithermal mineralisation (Au+base metal). To cite this article: V. Milu et al., C. R. Geoscience 335 (2003).     

甘肃北山炭山子—黄草泉一带水系沉积物地球化学特征及找矿远景

摘要：依据甘肃北山炭山子—黄草泉一带1∶5万水系沉积物测量成果,分析了区内地球化学参数特征及其元素的相关性,认为元素地球化学异常主要受断裂、地层及岩浆岩3种因素控制,即主要受大山头断裂带和庙庙井断裂带,蓟县系、寒武系和奥陶系地层,大山头、三个井基性-超基性杂岩体及华力西期中酸性侵入岩的控制。根据异常特征及成矿地质条件圈定出4处具较好找矿潜力的远景区,即大山头铜镍找矿远景区、三个井铜镍找矿远景区、庙庙井金铜钨钼多金属矿找矿远景区、黄草泉东金银多金属矿找矿远景区,为该区下一步找矿工作指明了方向。     

河南省新县赛山寨铜异常区找矿前景综合评价

在1∶5万水系沉积物测量的基础上,对大别山北麓赛山寨一带的元素分布特征、单元素异常特征、元素相关性分析、异常元素组合特征进行了研究,研究发现Cu、Au、Mo为区内具一定潜力的找矿指标。文章运用成矿系列、缺位找矿新理论,重新对大别山北麓赛山寨一带区域成矿地质条件及地球化学异常特征进行分析,从区域成矿背景、地层、构造等方面探讨了该铜多金属异常区的成矿条件,认为该异常区斑岩型钼矿成矿地质条件优越,深部应具有较大的找矿潜力,并为该地区今后的矿产勘查工作指明了方向。     

Cluster and R-mode factor analyses on soil geochemical data of Masjed-Daghi exploration area, northwestern Iran

Masjed-Daghi is located in Julfa sheet (1:100,000 series) in the northwest of Iran. The area consists of a very likely gold mineralization bearing epithermal mineralization which appears to be associated with a porphyry Cu–Mo system at deeper levels. Ninety-three soil samples were collected and analyzed for 13 elements (Au, Mo, Cu, Pb, Sn, Ag, Zn, Cr, Mn, Ba, Be, Ni, Co) by using emission spectrometry and atomic absorption spectrophotometry. The data were processed and interpreted using univariate and multivariate statistical analyses. The distribution of the majority of variables is slightly to moderately positively skewed which can be interpreted by log-normal model. Only Ni, Be, and Mn show normal distribution. Based on cluster analysis, the variables can be classified into two main groups. The first group consists of the main ore forming elements such as Au, Ag, and Ba which belong to epithermal system and Mo, Sn, and Cu which have more affiliation to porphyry mineralization. The principal component analysis extracted three factors. These factors calculated using varimax rotated R-mode factor loading matrix account for more than 65 % of the total variance. The first factor represents the main constituents of the epithermal system (Au, Ag, Ba) and its geochemical halo at the northeast of the study area. The second factor represents the main constituents of the porphyry system (Cu, Mo, Sn) and its geochemical halo in the western part of the study area which is overlapped with the volcanic rocks affected by local intrusions with higher alteration overprint. The third factor, however with less significance, represents Pb and Zn which are not the main ore constituents but can be considered as pathfinder elements. The results have been used to locate hidden orebodies using presented factor score mapping.     

中国大陆环境斑岩型矿床：基本地质特征、岩浆热液系统和成矿概念模型

中国大陆环境斑岩型矿床包括斑岩型Cu(-Mo、-Au)、斑岩型Mo、斑岩型Au和斑岩型Pb-Zn等矿床类型,主要产出于青藏高原大陆碰撞带、东秦岭大陆碰撞带和中国东中部燕山期陆内环境,在地球动力学背景、深部作用过程、岩浆起源演化、流体与金属来源等方面与岩浆弧环境斑岩型矿床存在重要差异.在大洋板块俯冲形成的岩浆弧,主要发育斑岩Cu-Au矿床或富金斑岩Cu矿(岛弧)和斑岩Cu-Mo及斑岩Mo矿床(陆缘弧).相比,在大陆碰撞带,晚碰撞构造转换环境发育斑岩Cu、Cu-Mo和Cu-Au矿床,矿床受斜交碰撞带的走滑断裂系统控制,后碰撞地壳伸展环境则主要发育斑岩Cu-Mo矿床,矿床受垂直于碰撞带的正断层系统控制;在陆内造山环境,早期发育斑岩Cu-Au矿床,晚期发育斑岩Pb-Zn矿床,它们主要沿古老的但再活化的岩石圈不连续带分布,受网格状断裂系统控制;在后造山(或非造山)伸展环境,则大量发育斑岩Mo矿和斑岩Au矿,它们则主要围绕大陆基底-克拉通(或地块)边缘分布,受再活化的岩石圈不连续带控制.大陆环境斑岩Cu(-Mo,-Au)矿床的含矿斑岩多为高钾钙碱性和钾玄质,以高钾为特征,显示埃达克岩地球化学特性.岩浆通常起源于加厚的新生镁铁质下地壳或拆沉的古老下地壳.上地幔通过三种可能的方式向岩浆系统供给金属Cu(和Au):①提供大批量的幔源岩浆并底垫于加厚下地壳底部,构成含Cu岩浆的源岩;②提供小批量的软流圈熔体交代和改造下地壳,并诱发其熔融;③与拆沉的下地壳岩浆熔体发生反应.大陆环境含Mo岩浆系统高SiO_2、高K_2O,岩相以花岗斑岩为主,花岗闪长斑岩次之,既不同于Climax型,又有别于石英二长斑岩型Mo矿床,岩浆起源于古老的下地壳.金属Mo主要为就地熔出,部分萃取于上部地壳.大陆环境含Pb-Zn花岗斑岩多属铝过饱和型,与S型花岗岩相当,以高δ~(18)O(>10‰)和高放射性Pb为特征,Sr-Nd-Pb同位素组成反映其来源于中下地壳的深熔作用,金属Pb-Zn主要来源于深融的壳层.大陆环境含Au岩浆系统以富B花岗闪长斑岩为主,常与矿前闪长岩密切共生.Sr-Nd-Pb同位素显示,含Au岩浆主要来源于上部地壳,但曾与幔源岩浆发生相互作用.金属Au部分来源于上地壳,部分来源于地幔岩浆.大陆环境斑岩型矿床显示各具特色的蚀变类型和蚀变分带,其中,斑岩型Cu(-Mo,-Au)矿热液蚀变遵循Lowell and Guilbert模式;斑岩型Mo矿主要发育钙硅酸盐化、钾硅酸盐化和石英-绢云母化;斑岩型Pb-Zn矿主要发育绿泥石-绢云母化和绢云母-碳酸盐化,缺乏钾硅酸盐化;斑岩型Au矿强烈发育中度泥化.斑岩型矿床的成矿流体初始为高温、高fO_2、高S、富金属的岩浆水,由浅成侵位的长英质岩浆房在应力松弛环境下出溶而来,晚期有天水不同程度地混入.Cu、Mo、Pb-Zn通常沉淀于流体分相和流体沸腾过程中,而Au则主要沉淀于岩浆-热液过渡阶段.     

吉林省敦化尔站矿区地球化学异常与钼矿体的相关性分析北大核心CSCD

吉林省敦化尔站矿区位于吉黑东部多金属成矿带中南部,以往资料表明有Mo、Cu等元素地球化学异常和斑岩体存在。为查明该区成矿条件,明确勘探思路,开展了水系沉积物、土壤元素地球化学和地物化综合剖面测量工作。通过对各元素分布、相关性和异常特征研究,发现水系和土壤地球化学异常具有较好重现性,R型聚类分析表明Mo与As、W元素相关性较好,主成矿元素为Mo元素,在地球化学高异常和低阻高极化率区域进行异常查证,发现钼矿体6条。钼矿体产于晚二叠世蚀变似斑状二长花岗岩体及其与围岩接触带,主要受北东向构造带控制,Mo和As等元素地球化学异常与矿体和蚀变带的辉钼矿、黄铁矿等关系密切。综合分析尔站矿区成矿地质条件,在已发现矿体北东和南东圈定靶区2个,区域上含前寒武系残片呈北东向展布的晚古生代花岗岩区是重点找矿地段。     

Controlling factors on changes of gold mineralization in Saqqez (Kurdistan) shear zones and reagent ratios of the mineralized section

Investigating the secondary geochemical environments, river, and stream sediments are considered as one of the geochemical exploratory methods on a primary scale, which is justifiable regarding the expenses and time of execution. Evaluating the factors related to mineralization of gold shear zones based on stream and river sediment sampling, located in the southwest of Saqqez (Kurdistan), is the main purpose of this research. Using multivariable analyses and investigating the cluster graph of the elements, controlling factors of mineralization have been investigated and effective factors are divided into two groups, one is probably related to the mineralization of gold in the region which contains the elements (Pb, Zn, Mo, Ag, Cu, Bi, etc.), and other is related to typical petrogenetic processes which contains the elements (Co, V, Cr, Ti, Ni, Mn, etc.). Based on factor analysis, seven main factors, which justify about 80% of the changes of the region, were introduced; factors 3, 1, 5, and 6 were related to mineralization and factors 2, 4, and 7 were related to the lithology of the region. For a more precise separation of the processes related to mineralization, various ratios were investigated and reagent ratios (Au/Bi and Au/Mo) were identified. It is found that the ranges of [23–100] for Au/Bi and [8–80] for Au/Mo are related to gold mineralization. Using the modeling of the reagent ratios probability graph and determining the exploratory threshold, significant parameters in gold mineralization were separated from insignificants.