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1.
安徽嘉山坡缕石结构特征的成因意义 总被引：1，自引：1，他引：0
本文对取自安徽嘉山坡缕石矿床不同层位的坡缕石粘土所做的红外光谱和Ｘ射线衍射分析表明：不同层位粘土的结构类型不同,坡缕石含量高的层位其结晶程度低;坡缕石含量低的层位其结晶程度高,为斜方晶系。文中对坡缕石的形成机理和造成结晶程度差异的原因进行了分析。 相似文献
2.
A palygorskite unit was discovered in a road cut of undifferentiated Tertiary limestone between the villages of El Pariso
and San Roman (18°49.309N, 88°37.861W) in the southeastern Yucatán Peninsula, Mexico. This is the southern most locality of
a clay-rich sedimentary unit reported in the literature for the Tertiary carbonates of the Yucatán Peninsula. This occurrence
indicates a much wider range of palygorskite-rich clay deposition than previously recognized. The lithology is 99% clay and
1% sand to silt size diagenetic quartz grains. The clay consists of approximately 85% palygorskite, 15% montmorillonite and
trace amounts of titanium oxides. EDS analyses on palygorskite are largely consistent with sedimentary palygorskites from
other coastal marine settings, however palygorskite has a low total Fe content (average = 0.40 wt% expressed as Fe2O3) compared to many other sedimentary palygorskites. Montmorillonite chemical compositions are typical and compared to the
palygorskite have substantially higher Fe2O3 concentrations (average = 3.90 wt%). The low percentage of coarse grains in the lithology combined with a high proportion
of palygorskite and lack of detrimental trace minerals suggest the deposit is of industrial grade; however, it has limited
reserves (6,000 m3). The unit could be potentially used in a wide array of environmental applications which are needed in the region including
liners for landfills and constructed wetlands. The unit is in a geographic location which would serve the expanding economy
of the region. This resource has the potential to have great impact on the quality of the local environment and the economy
of a region under great environmental threat. 相似文献
3.
A new deposit of high-quality bentonites and carbonate–palygorskite clays was discovered in the Paleogene section of the southwestern foothill of Southern Nuratau Range. The bentonites have a substantially montmorillonitic composition. Minor and admixture components are represented by illite, palygorskite, quartz, iron hydroxides, and other minerals. In terms of physicochemical properties, the bentonites are subdivided into the alkaline and alkaline-earth varieties. The carbonate–palygorskite clays possess a calcite–montmorillonite–palygorskite composition. The bentonites and carbonate–palygorskite clays formed in the alkaline medium of a marine basin. The major rock-forming montmorillonite formed as a result of the transformation of structurally similar clay minerals, while calcite and palygorskite are authigenic minerals. The bentonites and carbonate–palygorskite clays have been ascertained as a material suitable for the preparation of drilling muds, as adsorbents for the bleaching of cotton oil and purification of alcoholic products, as ointment bases and the principal component for medicinal preparations, and for other purposes. 相似文献
4.
凹凸石粘土与玄武岩的成因关系 总被引：4，自引：0，他引：4
在矿物组成研究的基础上，对比研究了凹凸棒石，蒙脱石，凹凸棒石粘土，蒙脱石粘土，玄武岩，风化玄武岩的化学组成。根据化学成分对比，分析了玄武岩与凹凸棒石粘土的成因关系，解释了玄武岩对凹凸棒石粘土的时空控制，结合地质观测，提出形成苏皖地区凹凸棒石粘土的物质成分基本上来源于玄岩的化学风化，但物质成分发生了较大的分异，凹凸棒石粘土不能直接同玄武岩经地表雨水的风化淋滤形成，而是玄武岩风化形成的蒙脱石经搬运沉积，再与镁质溶液反应形成，或凹凸棒石直接从富镁碱性溶液中结晶形成，凹凸棒石粘土形成的物理化学条件为偏碱性的还原条件。 相似文献
5.
Mark P. S. Krekeler Julie Morton Jill Lepp Cynthia M. Tselepis Mikhail Samsonov Lance E. Kearns 《Environmental Geology》2008,55(1):123-147
Clay-rich mine tailings from phosphate mine operations in Florida are a major environmental and economic problem. Options
for reclamation and restoration for these tailings are very limited and are fundamentally restricted by poor physical properties
such as low mechanical strength, low hydraulic conductivity, and heavy metal content. The major control on these bulk physical
properties is the mineralogy of the materials. Eight continuous push borings were obtained to investigate stratigraphy, mineralogy,
aspects of geochemistry, and bulk properties of a deposit of clay-rich mine tailings from a phosphate mine near Bartow, Florida
that ceased operations in the early 1970s. Stratigraphy is dominated by laminated clay-rich sediment with minor units of silt
and sand. An intact kaolinite liner occurs near the impoundment walls and the impoundment floor has approximately 4 m of relief.
Moisture content varies from 4.35 to 57.40 wt% and organic content varies from 0.41 to 9.53 wt%. Bulk XRF investigation indicates
that the P2O5 concentrations vary from approximately 4 to 21 wt%. A very strong correlation (r
2 = 0.92) between CaO and P2O5 indicates that apatite is a major control on the phosphate. The strong correlation (r
2 = 0.77) of Al2O3 and TiO2 suggests that the source materials for this deposit are comparatively uniform. A number of heavy metal elements and trace
elements occur. Cr, V, Ni, Cu are interpreted to be in phosphate minerals, largely apatite. Sr and Pb are interpreted to be
in both phyllosilicates and phosphate minerals. Two populations of apatite were observed in the clay-sized fraction, one that
was Fe and Si- bearing and another that was only Si-bearing. Fe-bearing apatite had Fe2O3 contents that varied from 0.38 to 5.32 wt% and SiO2 contents that varied from 0.90 to 3.32 wt%. The other apatite population had a wider range of SiO2 contents that varied from 0.77 to 8.80 wt%. TEM imaging shows that apatite grains are dominantly single crystals with lesser
amounts of aggregates. Wavellite commonly occurs as individual or clusters of lath-like crystals and the chemical composition
differs from the pure aluminium phosphate end member with average concentrations of components being that of CaO (1.57 wt%),
Fe2O3 (1.98 wt%), SiO2 (5.94 wt%). In the clay-sized phosphate minerals investigated no fluorine was found above detection limit (approximately
0.15 wt%), nor was any uranium, radium, heavy metal, or REE element detected. The phyllosilicate mineralogy of the deposit
is dominated by smectite (montmorillonite with lesser amounts of nontronite), palygorskite, illite and kaolinite. No systematic
variation in the relative proportions of phyllosilicates was observed in the clay deposit. Energy dispersive spectroscopy
EDS analysis indicates that chemical compositions of phyllosilicates are somewhat typical but overall are enriched with respect
to Fe compared to theoretical end members. The relative enrichment of Fe is interpreted to be a primary sedimentary feature.
Ca content in smectite minerals is high and may inhibit stabilization using lime or similar methods. The high percentages
of montmorillonite and palygorskite explain the high bulk water contents observed. This investigation provides fundamentally
new details regarding clay tailing deposits from closed phosphate mines in central Florida which can be used in restoration
and reclamation efforts. 相似文献
6.
杨斜中型金矿床是东秦岭杨斜-丰北河地区典型的石英脉型金矿床,成矿与区内石英闪长玢岩密切相关,具中高温蚀变特征及矿物组成。LA-ICP-MS锆石U-Pb测年结果表明,石英闪长玢岩锆石206Pb/238U加权平均年龄为149.5±2.7 Ma,谐和年龄为149.5±2.1 Ma,属晚侏罗世。岩石地球化学研究显示,石英闪长玢岩具有高SiO2(65.53%~65.76%)、高Al2O3(15.65%~15.87%)、富碱(N2O+K2O=8.07%~8.30%)及贫MgO(1.37%~1.40%)特征,属于高钾钙碱性准铝质系列岩石;相对富集Rb、Ba、K、Pb、Sr等大离子亲石元素和LREE,亏损Nb、Ta、Ti等高场强元素和HREE;其高Sr、高Sr/Y、低Y和低Yb值及正Eu异常等特征参数,与典型埃达克质岩一致,岩浆应起源于加厚下地壳的部分熔融。综合研究认为,杨斜金矿属岩浆期后热液型金矿床,成岩成矿时代一致,形成于秦岭造山带晚侏罗世-早白垩世陆内俯冲向伸展转换的构造环境。 相似文献
7.
8.
The Bitincke nickel laterite deposit, located in the south east of Albania, contains an estimated ore resource of 35.6?Mt of nickel ore with a grade of 1.2?% Ni. The deposit developed on peridotites within Late Jurassic ophiolites which were obducted in the Early Cretaceous and which form part of the Albanian Mirdita ophiolite zone. Limestones and conglomerates overlying the deposit delimit the minimum age of lateritization to the mid-Eocene. The laterite is composed of two distinct ore zones characterized by silicate nickel and iron oxide phases. Within the silicate zone, Ni concentrations reach a maximum of 1.5?wt% and although laterally and vertically variable this zone is typically characterized by olivine and serpentine at the base of the horizon which are gradually replaced by secondary silicates and iron oxides up section. The boundary between the silicate and the oxide zone above is normally sharp and characterized by an increase in Fe2O3 (from ~10 to 80?wt%), decreases in SiO2 (from ~30 to 5?wt%) and a dramatic reduction in MgO content (from ~10 to 0.1?wt%). The oxide horizon is dominated by goethite and displays relatively little variation in textural morphology or geochemistry. Nickel concentrations are greatest near the base of this zone, reaching a maximum of 2.3?wt%. Weathering profile formation and variation in the thickness of the deposit was controlled by the interaction between topography, faulting and protolith fracture density. The oxide zone formed on topographic highs was subject to increased rates of erosion, whereas the laterite profile within topographic lows, and in areas of relatively high fracture density, tends to be thicker due to increased permeability. The most substantive sections of the Ni laterite weathering profile developed in small fault controlled basins and were preserved by the deposition of a sequence of limestones and mudstones. 相似文献
9.
Geology and Metallogenesis of the Sawayaerdun Gold Deposit in the Southwestern Tianshan Mountains, Xinjiang, China 总被引：2，自引：0，他引：2
Fuquan Yang Jingwen Mao Yitian Wang Frank P. Bierlein Huishou Ye Mengwen Li Caisheng Zhao Jinhua Ye 《Resource Geology》2007,57(1):57-75
The Sawayaerdun gold deposit, located in Wuqia County, Southwest Tianshan, China, occurs in Upper Silurian and Lower Devonian low‐grade metamorphic carbonaceous turbidites. The orebodies are controlled by a series of NE‐NNE‐trending, brittle–ductile shear zones. Twenty‐four gold mineralized zones have been recognized in the Sawayaerdun ore deposit. Among these, the up to 4‐km‐long and 200‐m wide No. IV mineralized zone is economically the most important. The average gold grade is 1–6 g/t. Gold reserves of the Sawayaerdun deposit have been identified at approximately 37 tonnes and an inferred resource of 123 tonnes. Hydrothermal alteration is characterized by silicification, pyritization, arsenopyritization, sericitization, carbonatization and chloritization. On the basis of field evidence and petrographic analysis, five stages of vein emplacement and hydrothermal mineralization can be distinguished: stage 1, early quartz stage, characterized by the occurrence of quartz veins; stage 2, arsenopyrite–pyrite–quartz stage, characterized by the formation of auriferous quartz veinlets and stockworks; stage 3, polymetallic sulfide quartz stage, characterized by the presence of auriferous polymetallic sulfide quartz veinlets and stockworks; stage 4, antimony–quartz stage, characterized by the formation of stibnite–jamesonite quartz veins; and stage 5, quartz–carbonate vein stage. Stages 2 and 3 represent the main gold mineralization, with stage 4 representing a major antimony mineralization episode in the Sawayaerdun deposit. Two types of fluid inclusion, namely H2O–NaCl and H2O–CO2–NaCl types, have been recognized in quartz and calcite. Aqueous inclusions show a wide range of homogenization temperatures from 125 to 340°C, and can be correlated with the mineralization stage during which the inclusions formed. Similarly, salinities and densities of these fluids range for each stage of mineralization from 2.57 to 22 equivalent wt% NaCl and 0.76 to 1.05 g/cm3, respectively. The ore‐forming fluids thus are representative of a medium‐ to low‐temperature, low‐ to medium‐salinity H2O–NaCl–CO2–CH4–N2 system. The δ34SCDT values of sulfides associated with mineralization fall into a narrow range of ?3.0 to +2.6‰ with a mean of +0.1‰. The δ13CPDB values of dolomite and siderite from the Sawayaerdun gold deposit range from ?5.4 to ?0.6‰, possibly reflecting derivation of the carbonate carbon from a mixed magmatic/sedimentary source. Changes in physico‐chemical conditions and composition of the hydrothermal fluids, water–rock exchange and immiscibility of hydrothermal fluids are inferred to have played important roles in the ore‐forming process of the Sawayaerdun gold–antimony deposit. 相似文献
10.
Nadja Zupan Hajna Roman Skála Asma Al-Farraj Martin Šťastný Pavel Bosák 《Arabian Journal of Geosciences》2016,9(17):689
The x-ray powder diffraction identification of clay minerals both in bulk samples and in separated clay fraction confirmed the presence of palygorskite in samples of cave sediments from Wadi Haqil (the western slopes of Musandam Mountains; Ras Al-Khaimah Emirate, UAE). Samples contain quartz, gypsum, smectite, kaolinite, calcite, and palygorskite, some of them chlorite, illite, feldspars, and goethite. Calcite dominates in most samples; smectite prevails in clay fraction. After heating, the 001 reflection of chlorite shifts to higher diffraction angles and its intensity decreases; these features indicate that the chlorite represent a Fe-dominant species. Unit-cell dimensions of major phases as refined by the Rietveld method are in agreement with literature data. Chemical composition of palygorskite was derived from unit-cell dimensions as follows: MgO content is 11–14 wt% and Al2O3 10–13 wt%. Clay mineralogy is only hard to ascertain from the scanning electron microscope (SEM) images even after being combined with the energy-dispersive spectrometer data. The SEM was also used to characterize gypsum grains; they often display flow deformation features. Studied cave sediments represent palygorskite-bearing weathering products and desert soils re-deposited from the cave surroundings by slope processes and wind and/or surface runoff. The mixture with other clay minerals, quartz, feldspars, etc. supports this interpretation. Fine-grained quartz fraction is probably wind-blown. Gypsum and calcite are the precipitates (crusts and/or cements), although gypsum can also be re-deposited from omnipresent gypsum-cemented surface sediments. 相似文献
11.
The Jingtieshan deposit occurs in a Precambrian tectonic-stratigraphic terrane within the Northern Qilian Caledonian Orogen,
and is generally considered as a Superior-type iron formation. The deposit is characterized by Fe-Si-Ba and Cu mineralization
and consists of two types of orebodies, an upper jasper-barite-iron deposit and a lower copper sulfide deposit. The iron orebodies
occur as independent stratigraphic layers concordant within a thick argillaceous succession, and exhibit fine-grained textures
and well-developed sedimentary layering. The ores are predominantly composed of specularite and jasper with lesser amounts
of magnetite, hematite, siderite, and barite. The presence of barite, hematite and jasper as major components shows that the
iron ores were precipitated in a relatively oxidized ocean floor environment. The Cu orebody directly underlies the iron ore
and is hosted by chlorite-sericite-quartz phyllite. The Cu mineralization is composed of pyrite and chalcopyrite and is characterized
by stockwork. The disseminated and stockwork Cu mineralization is metamorphosed and concordant with respect to foliation,
indicating pre-fabric development, i.e. pre-metamorphism, and was probably originally formed by reduced fluids reacting at
the base of and within the oxide iron formation. Geochemical data show that the jasper-barite-iron ores, which resemble Superior-type
iron formations, have a high input of hydrothermal-hydrogeneous elements (SiO2, av.=56%; Fe2O3t, av.=30%; Mn, av.=0.45%; BaO, av.=16.7%) with minimal terrigeneous input (<15% combined Al2O3, TiO2, K2O, MgO, etc.). The δ34S of exhalative barite varies from 28 to 34‰, which is very heavy with respect to other Late Proterozoic sulfate-bearing deposits,
except those of circa 600 Ma in which the sulfides range from 8 to 20‰. The sulfur isotope data indicate that the barite was
formed by the mixing of a Ba-rich hydrothermal fluid with sulfate-rich ambient seawater and that the sulfides ores were most
probably derived from the reduction of seawater sulfate during subsurface reaction with ferrous iron-bearing minerals. These
data are consistent with the jasper-barite-iron deposit forming by hydrothermal exhalative and chemical sedimentary processes
on the floor of an ocean basin, and with the Cu mineralization forming by hydrothermal filling and replacement in base of
and within the iron formation.
Received: 19 March 1997 / Accepted: 14 May 1998 相似文献
12.
Yunfei Zhou Jiuhua Xu Lihua Shan Xihui Cheng Yueping Deng Wenhuan Feng Lingxiao Qiao 《Resource Geology》2019,69(1):43-64
The Xiaojiashan tungsten deposit is located about 200 km northwest of Hami City, the Eastern Tianshan orogenic belt, Xinjiang, northwestern China, and is a quartz vein‐type tungsten deposit. Combined fluid inclusion microthermometry, host rock geochemistry, and H–O isotopic compositions are used to constrain the ore genesis and tectonic setting of the Xiaojiashan tungsten deposit. The orebodies occur in granite intrusions adjacent to the metamorphic crystal tuff, which consists of the second lithological section of the first Sub‐Formation of the Dananhu Formation (D2d 12). Biotite granite is the most widely distributed intrusive bodies in the Xiaojiashan tungsten deposit. Altered diorite and metamorphic crystal tuff are the main surrounding rocks. The granite belongs to peraluminous A‐type granite with high potassic calc‐alkaline series, and all rocks show light Rare Earth Element (REE)‐enriched patterns. The trace element characters suggest that crystallization differentiation might even occur in the diagenetic process. The granite belongs to postcollisional extension granite, and the rocks formed in an extensional tectonic environment, which might result from magma activity in such an extensional tectonic environment. Tungsten‐bearing quartz veins are divided into gray quartz vein and white quartz veins. Based on petrography observation, fluid inclusions in both kinds of vein quartz are mainly aqueous inclusions. Microthermometry shows that gray quartz veins have 143–354°C of Th, and white quartz veins have 154–312°C of Th. The laser‐Raman test shows that CO2 is found in fluid inclusions of the tungsten‐bearing quartz veins. Quadrupole mass spectrometry reveals that fluid inclusions contain major vapor‐phase contents of CO2, H2O. Meanwhile, fluid inclusions contain major liquid‐phase contents of Cl?, Na+. It can be speculated that the ore‐forming fluid of the Xiaojiashan tungsten deposit is characterized by an H2O–CO2, low salinity, and H2O–CO2–NaCl system. The range of hydrogen and oxygen isotope compositions indicated that the ore‐forming fluids of the tungsten deposit were mainly magmatic water. The ore‐forming age of the Xiaojiashan deposit should to be ~227 Ma. During the ore‐forming process, the magmatic water had separated from magmatic intrusions, and the ore‐bearing complex was taken to a portion where tungsten‐bearing ores could be mineralized. The magmatic fluid was mixed by meteoric water in the late stage. 相似文献
13.
江苏白土山坡缕石粘土矿性能及其应用研究 总被引：2，自引：0，他引：2
白土山坡缕石粘土矿床集中赋存于上第三系上新统桂五组。可划分出坡缕石粘土、白云石坡缕石粘土、混合粘土、蒙脱石粘土、海泡石粘土、方解石坡缕石粘土 6种自然类型。其中产于Ⅲ号矿层的坡缕粘土矿质量较好 ,具较高的应用价值。采用加入适量硅酸钠溶液的提纯流程 ,坡缕石矿石品位从30 .9%提高到 84.5 %。经研究坡缕石品位越高 ,导热系数越小 ;密度、含水量越大 ,导热系数越大。坡缕石在 6 5 0℃以下能保持晶体结构基本框架 ,仍具有较低导热系数。经多次试验 ,研制成功性能优良的Ⅲ号隔热保温涂料。 相似文献
14.
15.
Yang Liqiang Deng Jun Zhang Jing Guo Chunying Gao Bangfei Gong Qingjie Wang Qingfei Jiang Shaoqing Yu Haijun 《中国地质大学学报(英文版)》2008,19(4):378-390
The recently discovered Damoqujia (大磨曲家) gold deposit is a large shear zone-hosted gold deposit of disseminated sulphides located in the north of the Zhaoping (招平) fault zone, Jiaodong (胶东) gold province, China. In order to distinguish the temperature range of cluster inclusions from different mineralization stages and measure their compositions, 16 fluid inclusions and 5 isotopic geochemistry samples were collected for this study. Corresponding to different mineralization stages, the multirange peaks of quartz decrepitation temperature (250-270, 310-360 and 380-430℃(2) indicate that the activity of ore-forming fluids is characterized by multistage. The ore-forming fluids were predominantly of high-temperature fluid system (HTFS) by CO2-rich, and SO2-4-K type magmatic fluid during the early stage of mineralization and were subsequently affected by low-temperature fluid system (LTFS) of CH4-rich, and Cl--Na /Ca2 type meteoric fluid during the late stage of mineralization. Gold is transferred by Au-HS- complex in the HTFS, and Au-Cl- complex can be more important in the LTFS. The transition of fluids from deeper to shallow environments results in mixing between the HTFS and LTFS, which might be one of the most key reasons for gold precipitation and large-scale mineralization. The ore-forming fluids are characterized by high-temperature, strong-activity, and superimposed mineralization, so that there is a great probability of forming large and rich ore deposit in the Damoqujia gold deposit. The main bodies are preserved and extend toward deeper parts, thereby suggesting a great potential in future. 相似文献
16.
Tectonic Settings and Geological Implications of Neoproterozoic Liujiaping VMS Deposit,Northwestern Yangtze Block,China 
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下载免费PDF全文 Liujiaping VMS (volcanic massive sulfide) deposit contains mainly copper and zinc, which is located at the Longmenshan orogenic belt of the northwestern margin of Yangtze block. The deposit is hosted in Neoproterozoic Datan terrane (composed of Datan granitoids and Liujiaping group) and is a typical, and the biggest, VMS deposit in this area. The Datan granitoids and Liujiaping group are contemporary and both parental magmas have the same genesis. The tectonic evolution history of Northwestern Yangtze is complicated. Chronology, isotope and geochemistry of the Liujiaping VMS ores and wall rocks (especially the Datan granitoids) are analyzed to restrict the tectonic progress. High‐precision secondary ion mass spectrometry (SIMS) analysis of the Datan granitoids resulted in two concordant ages, 815.5 ± 3.2 Ma and 835.5 ± 2.6 Ma, which are contemporary with the Liujiaping Cu–Zn ore and volcanics. The wall rocks are characterized by enrichment in LREE and with a weak negative anomaly of Eu. The Pb isotope data of sulfide and volcanics from the Liujiaping deposit indicate that the material source is lower crust. Together with variable negative anomalies of high strength field elements HFSE (Th, Nb, Ta, Zr, Hf, P and Ti), positive εNd (825 Ma) values (+1.8 to +3.1) and the Nd model age T2DM = 1.2–1.3 Ga, it shows that the Liujiaping deposit and wall rocks were formed by partial melting of Mesoproterozoic lower crust. Geological and geochemical characteristics of Liujiaping deposit indicate that this deposit was formed during subduction of the oceanic crust. This study clarified that that the Liujiaping deposit and the northwestern margin of the Yangtze block were part of an arc setting at ~820 Ma rather than intra‐continental rift. 相似文献
17.
福建大坪花岗斑岩体位于永定县城南部的大石凹—蓝地火山喷发盆地,具斑状结构,基质呈霏细结构、细-微粒结构。文章运用电子探针(EMPA)和激光剥蚀电感耦合等离子体质谱仪(LA-ICP-MS)等技术,对大坪岩体ZK10001钻孔中不同深度的岩石样品进行了矿物和岩石化学分析。分析结果表明,大坪岩体岩性为黑鳞云母碱长花岗斑岩,属于过铝质钙碱性花岗岩,具有较高的分异演化程度,Nb2O5和Ta2O5含量达到了花岗岩型稀有金属矿床的工业品位。铌钽矿物主要与黄玉、萤石的集合体呈稀疏浸染状、星点状产于基质间隙内,其次以星点状存在于石英和长石斑晶中。矿石矿物赋存特征与宜春钽铌矿床类似,可能具有一定的可选性和经济价值。大坪岩体的铌钽富集特征不同于斑岩型铜、钼矿床,与花岗岩型铌钽矿床也存在较大的差别,铌钽的富集过程经历了深部斑晶阶段和浅部基质阶段两阶段岩浆结晶分异作用,F等挥发分促进了铌钽在结晶残余岩浆中富集,在基质间隙间沉淀。大坪矿化岩体的发现暗示斑岩型铌钽矿床存在的可能性。 相似文献
18.
阿沙哇义金矿位于中国新疆南天山造山带,属于著名的中亚南天山锑-汞-金成矿带的东延部分。该矿床严格受断裂所控制,以浸染状黄铁矿化、毒砂化为特征。矿化可分为三个阶段:早期无矿或贫矿石英阶段,中期石英多金属硫化物阶段,晚期石英-碳酸盐阶段。其中,中期是主要成矿阶段。成矿流体气相成分以H_2O为主,摩尔含量为75%～93%,其次为CO_2,摩尔含量为6%～25%,其余为CH_4、C_2H_6、H_2S、N_2和Ar;液相成分阳离子以Na~+为主,含少量K~+、Ca~(2+)离子,阴离子以Cl~-为主,SO~(2-)次之;矿石的Au含量与其流体的CO_2含量呈反相关,与K~+含量呈正相关。硫化物成分分析结果表明:(1)围岩地层和矿石中的黄铁矿和毒砂是重要的载金矿物,黄铁矿Au含量为0～0. 09%,平均值0. 03%;毒砂Au含量为0～0. 28%,平均值0. 07%;(2)黄铁矿和毒砂Au含量与其自形程度没有明显的相关性;(3)环带状黄铁矿较均质结构黄铁矿具有更高的Au含量;(4)岩体中的黄铁矿几乎不含Au。在成矿构造环境、成矿流体特征及演化、金矿富集机制、成矿温压条件等方面,该矿床与世界上大多数造山型金矿显示出一致性,成矿类型应属于剥蚀程度较浅的造山型金矿。断层阀作用控制的断层愈合-破裂导致的流体不混溶作用是本区金富集、沉淀的最重要机制,但流体混合机制对金的富集沉淀也发挥了作用。黄铁矿、毒砂发育及较多的含炭物质三者共存是本区寻找富矿的关键标志。 相似文献
19.
岩房湾铅锌矿位于陕西省太白县境内。文章通过矿床的成矿流体及地球化学特征研究,对比同属于风太矿田的八方山—二里河、铅硐山、银母寺等大型铅锌矿,认为岩房湾铅锌矿床成矿流体为中-低盐度、中-低温、含有CO2,N2,CH4等气体的还原性流体体系,并显示出热卤水成因特点。流体包裹体主要包括水溶液包裹体、CO2-H2O-NaCl包裹体、纯CO2包裹体3种类型,为不混溶包裹体群,均一温度高于八方山—二里河等铅锌矿,可能与西坝岩体的侵入有关。氢、氧同位素特征显示成矿流体为岩浆水与变质水的混合,碳、氧同位素特征显示成矿过程中碳质来源于泥盆纪正常海相碳酸盐岩,铅同位素特征显示出造山带与上地壳混合来源的特点。岩房湾铅锌矿成矿流体和同位素特征与同区大型SEDEX型铅锌矿存在着一些差异,不宜笼统将其与同区热水沉积成因大型铅锌矿床归为同一类型。 相似文献
20.
河北滦平周台子条带状铁矿地质特征、围岩时代及其地质意义 总被引：5，自引：4，他引：1
河北滦平县周台子铁矿位于华北克拉通北缘,是产于前寒武纪单塔子群变质岩系中的鞍山式铁矿,具有条带状铁建造(BIF)特征。矿石主要呈条带状构造,有的呈条纹和致密块状构造。矿石类型主要以石英磁铁矿型为主,含铁介于30%~35%。前寒武纪变质岩是矿床的主要围岩,出露有黑云母(角闪)斜长片麻岩和斜长角闪岩,局部见花岗片麻岩。原岩恢复表明,黑云母(角闪)斜长片麻岩的原岩为英安岩-流纹岩,斜长角闪岩原岩为玄武岩。花岗片麻岩的SiO2含量大于56%,MgO含量小于3%,Al2O3含量大于15%,Sr含量大于500×10-6,Yb含量均小于1.9×10-6,轻重稀土元素分异明显,重稀土元素强烈亏损,并且Eu负异常不明显,表明该片麻岩具埃达克质岩石的地球化学特征。锆石U-Pb定年结果显示出几组年龄,分别是2512±21Ma, 2452±9.6Ma,2394±55Ma。大体看,2512Ma代表了火山喷发和周台子铁矿BIF沉淀年龄,2452Ma左右的锆石年龄代表了TTG质花岗片麻岩的侵位结晶年龄,2394Ma锆石年龄代表了周台子铁矿经历了一次变质作用,并对原有的岩石和矿石进行了改造。锆石Hf同位素特征显示斜长角闪岩和TTG质片麻岩的岩浆源区受到过古老地壳物质的混染。周台子铁矿构造环境可能是与裂谷有关的张性环境。 相似文献