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1.
The hydrogen isotopic composition of structural water in MnO(OH) minerals from manganese oxide and massive sulfide deposits
(Kuroko) in Tertiary formations fall within a narrow range from -261 to -275 permil relative to standard mean ocean water
(SMOW). The δD of two manganites from manganese deposits in Paleozoic formations were -236 and -298 permil, indicating a wider
range than in those of Tertiary manganese deposits. The MnO(OH) minerals are more deuterium-depleted. than any other hydrothermal
minerals reported to date.
Hydrogen isotopic fractionation factors between manganite and water were experimentally determined to be 0.7894, 0.7958, and
0.8078 at 150°, 200°, and 250° C, respectively, under hydrothermal conditions at 500 bars. The present experimental results
indicate that if manganites were formed at temperatures below 250° C under isotopic equilibrium conditions, then most manganite
mineralization in the ore deposits must have precipitated from meteoric hydrothermal solutions. 相似文献
2.
《International Geology Review》2012,54(6):520-541
The major Gushan iron oxide deposit, typical of the Middle‐Lower Yangtze River Valley, is located in the eastern Yangtze craton. Such deposits are generally considered to be genetically related to Yanshanian subvolcanic‐volcanic rocks and are temporally‐spatially associated with ca. 129.3–137.5 Ma dioritic porphyries. The latter have a very narrow 87Sr/86Sr range of 0.7064 to 0.7066 and low ?Nd(t) values of ?5.8 to ?5.7, suggesting that the porphyries were produced by mantle‐derived magmas that were crustally contaminated during magma ascent. The ore bodies occur mainly along the contact zone between dioritic porphyries and the sedimentary country rocks. The most important ore types are massive and brecciated ores which together make up 90 vol.‐% of the deposit. The massive type generally occurs as large veins consisting predominantly of magnetite (hematite) with minor apatite. The brecciated type is characterized by angular fragments of wall‐rocks that are cemented by fine‐grained magnetite. Stockwork iron ores occur as irregular veins and networks, especially with pectinate structure; they are composed of low‐temperature minerals (e.g. calcite), which indicate a hydrothermal process. The similar rare earth element patterns of apatite from the massive ores, brecciated ores and the porphyries, coupled with high‐temperature fluids (1000°C) suggest that they are magmatic in origin. Furthermore, melt flow structure commonly developed in massive ores and the absence of silicate minerals and cumulate textures suggest that the iron ores formed by the separation of an immiscible oxide melt from the silicate melt rather than by crystal fractionation. Combined with theoretical and experimental studies, we propose that the introduction of phosphorus due to crustal contamination during mantle‐derived magma ascent could have been a crucial factor that led to the formation of an immiscible oxide melt from the silicate magma. 相似文献
3.
Sabina Strmić Palinkaš Jorge E. Spangenberg Ladislav A. Palinkaš 《Mineralium Deposita》2009,44(8):893-913
The Ljubija siderite deposits, hosted by a Carboniferous sedimentary complex within the Inner Dinarides, occur as stratabound
replacement-type ore bodies in limestone blocks and as siderite–sulfides veins in shale. Three principal types of ore textures
have been recognized including massive dark siderite and ankerite, siderite with zebra texture, and siderite veins. The ore
and host rocks have been investigated by a combination of inorganic (major, trace, and rare earth element concentrations),
organic (characterization of hydrocarbons including biomarkers), and stable isotope geochemical methods (isotope ratios of
carbonates, sulfides, sulfates, kerogen, and individual hydrocarbons). New results indicate a marine origin of the host carbonates
and a hydrothermal–metasomatic origin of the Fe mineralization. The differences in ore textures (e.g., massive siderite, zebra
siderite) are attributed to physicochemical variations (e.g., changes in acidity, temperature, and/or salinity) of the mineralizing
fluids and to the succession and intensity of replacement of host limestone. Vein siderite was formed by precipitation from
hydrothermal fluids in the late stage of mineralization. The equilibrium fractionation of stable isotopes reveals higher formation
temperatures for zebra siderites (around 245°C) then for siderite vein (around 185°C). Sulfur isotope ratios suggest Permian
seawater or Permian evaporites as the main sulfur source. Fluid inclusion composition confirms a contribution of the Permian
seawater to the mineralizing fluids and accord with a Permian mineralization age. Organic geochemistry data reflect mixing
of hydrocarbons at the ore site and support the hydrothermal–metasomatic origin of the Ljubija iron deposits. 相似文献
4.
《International Geology Review》2012,54(8):702-723
Silver deposits of the South Pamir region of Tajikistan occur as siderite veins with sulfosalts and sulfides, and formed during a late Mesozoic-early Alpine cycle of rifting and orogenesis. Three mineral-geochemical types of ore deposits that occur in several ore districts are recognized: Ag-Sb, Ag-Pb, and Ag-Hg. The Ag vein deposits all occur in terrigenous-carbonate sedimentary rocks and in intrusive granites. The veins are controlled by late Mesozoic faults, and are the products of the last endogenous event in the region. The most significant group of Ag-Sb vein deposits is located in the Bazardara ore district. Three stages of mineralization are recognized in this region: siderite-tetrahedrite, quartz-tetrahedrite, and quartz-galena-freibergite. Most of the veins were deposited during the first stage. Tetrahedrite is the prevailing and most economically important mineral, and contains 0.2 to 15.5% Ag. Associated freibergite contains from 19.5 to 32% Ag. Fluid-inclusion studies indicate that Ag-Sb ore deposits formed over a temperature interval of 280-100°C and pressure of 750-450 bars. Ore deposits were formed from saline solutions (up to 38%) that in late stages were diluted (1.5%). Considerable fluctuations apparently occurred in the associated regional hydrothermal system. Temperature gradients ranged from 8-10°C/100 meters to 14-15°C/100 meters. Temperatures and concentrations of hydrothermal solutions significantly decreased from the main ore-controlling fault toward the north and south flanks of the ore districts. 相似文献
5.
非洲锰矿床成矿规律、开发利用与勘查建议 总被引：1，自引：0，他引：1
锰矿是我国重要的战略矿产资源,需求量不断增长,长期依赖国外资源保障供需关系。本文总结分析了非洲锰矿资源的特点、矿床类型与成矿规律等地质特征与勘查开发利用及贸易现状。分析表明：非洲是全球探明锰矿储量和资源量最多的地区,具有分布集中,规模大、品位高、杂质少的特点;锰矿床类型主要有条带状含铁建造（BIF）型、海相沉积型、海相火山-沉积型、陆相（湖相三角洲）沉积型、岩浆热液型等五大类,普遍遭受表生风化淋滤（溶蚀）作用改造;主要分布在卡普瓦尔克拉通、刚果克拉通西北部的加蓬地块和西非克拉通南缘的马恩-莱奥地盾中;成矿时代主要集中于前寒武纪,尤其是2.2~2.0Ga;非洲锰矿资源的勘查开发程度较高,其中南非是非洲锰矿勘查程度最高的国家,中非、北非国家的勘查开发程度较低;南非是全球最大的锰矿石生产国和锰矿产品出口国,目前占全球出口量的68.19%以上,我国是非洲锰矿产的最大出口地,占其出口总量的70.19%。建议：我国在非洲的勘查应重点关注非洲中部的条带状含铁建造（BIF）型锰矿和海相火山-沉积型锰矿;在非洲已有的中企基础上,组建大型的集团公司,建立多元的锰矿资源供应体系。 相似文献
6.
The first data on the mineral composition and formation conditions of manganese ore at the Chapsordag and Malosyrsky deposits
in the Askiz ore district of Khakassia are integrated and systematized. The detailed mineralogical mapping of the deposits
has been carried out. The identification of minerals and examination of the ore microstructure were performed with optical
microscopy in transmitted and reflected light and using SEM/EDS, EMPA, XRD, IRS, and other methods. It was established that
the ore mineralization is spatially and genetically related to the Early Devonian magmatism and accompanying hydrothermal
activity and metasomatism. Syngenetic braunite was detected for the first time in elevated amounts reaching an economic level
in the devitrified groundmass of volcanic rocks, in cement of lava breccia, and in fragments in pyroclastic rocks. By analogy
with iron deposits, this magmatogenic type of manganese mineralization is regarded as ore lavas and tuffs combined with metasomatic
and hydrothermal mineral assemblages into a strata-bound orebearing complex and as a source of hydrothermal metasomatic ore.
The elevated Mn content in magmatic melts of the Early Devonian trachybasalt-trachyandesite-trachydacite association is caused
by assimilation of Riphean and Lower Cambrian high-Mn carbonate sequences in crustal magma chambers. In contours of economic
orebodies, the hydrothermal economic ore is recognized as sites of massive, patchy and impregnated, brecciated, stringer-disseminated,
and disseminated varieties. High-grade massive ore occurs as stratiform and branching bodies up to 1.5 m thick and a few tens
of meters long and as smaller pocketlike bodies. Braunite and pyrolusite (polianite) are major ore minerals varying in size,
degree of crystallinity, and character of intergrowths with associating minerals. Gangue minerals include carbonates, sulfates,
albite, quartz, chlorite, actinolite, piemontite, and okhotskite, a Mn-pumpellyite identified in Russia for the first time
and studied in detail in this paper. The veined hydrothermal ore is classified as a calcite-barite-pyrolusite type. The crystallization
temperature of hydrothermal metasomatic ore is estimated at 350–180°C; oxygen fugacity is above the hematite-magnetite buffer.
The surface of high-grade ore is encrusted with supergene goethite-hydrogoethite, chalcedony-hematite, and pyrolusite-psilomelane
crusts and veinlets (less than 1% of the bulk ore mass). The data obtained facilitate prospecting for high-quality manganese
ore at walls of superimposed rifts in fold regions, including large economic manganese concentrations in the form of ore lavas
and tuffs as products of solidification of metalliferous melt. 相似文献
7.
8.
QIU Zhengjie FAN Hongrui LIU Xuan WEN Bojie HU Fangfang YANG Kuifeng GUO Shuanglong ZHAO Fengchun 《《地质学报》英文版》2015,89(3):726-745
The Hujiayu Cu deposit,representative of the "HuBi-type" Cu deposits in the Zhongtiao Mountains district in the southern edge of the North China Craton,is primarily hosted in graphitebearing schists and carbonate rocks.The ore minerals comprise mainly chalcopyrite,with minor sphalerite,siegenite[(Co,Ni)_3S_4],and clausthalite[Pb(S,Se)].The gangue minerals are mainly quartz and dolomite,with minor albite.Four fluid inclusion types were recognized in the chalcopyrite-pyrite-dolomite-quartz veins,including CO_2-rich inclusions(type Ⅰ),low-salinity,liquid-dominated,biphase aqueous inclusions(type Ⅱ),solid-bearing aqueous inclusions(type Ⅲ),and solid-bearing aqueous-carbonic inclusions(type Ⅳ).Type I inclusion can be further divided into two sub-types,i.e.,monophase CO_2 inclusions(type Ⅰa) and biphase CO_2-rich inclusions(with a visible aqueous phase),and type Ⅲ inclusion is divided into a subtype with a halite daughter mineral(type Ⅲa) and a subtype with multiple solids(type Ⅲb).Various fluid inclusion assemblages(FIAs) were identified through petrographic observations,and were classified into four groups.The group-1 FIA,consisting of monophase CO_2 inclusions(type Ⅰa),homogenized into the liquid phase in a large range of temperatures from-1 to 28℃,suggesting post-entrapment modification.The group-2 FIA consists of type Ⅰb,Ⅲb and Ⅳ inclusions,and is interpreted to reflect fluid immiscibility.The group-3 FIA comprises type Ⅱ and Ⅲa inclusions,and the group-4FIA consists of type Ⅱ inclusions with consistent phase ratios.The group-1 and group-2 FIAs are interpreted to be entrapped during mineralization,whereas group-3 and group-4 FIAs probably represent the post-mineralization fluids.The solid CO_2 melting temperatures range from-60.6 to56.6℃ and from-66.0 to-63.4℃ for type Ⅰa and type Ⅳ inclusions,respectively.The homogenization temperatures for type Ⅱ inclusions range from 132 to 170℃ for group-3 FIAs and115 to 219℃ for group-4 FIAs.The halite melting temperatures range from 530 to 562℃ for typeⅢ b and Ⅳ inclusions,whereas those for type Ⅲa inclusions range from 198 to 398℃.Laser Raman and SEM-EDS results show that the gas species in fluid inclusions are mainly CO_2 with minor CH_4,and the solids are dominated by calcite and halite.The calcite in the hosting marble and dolomite in the hydrothermal veins have δ~(13)C_(V-pdb) values of-0.2 to 1.2‰ and-1.2 to-6.3‰,and δ~(18)O_(v-smow) values of 14.0 to 20.8 ‰ and 13.2 to 14.3‰,respectively.The fluid inclusion and carbon-oxygen isotope data suggest that the ore-forming fluids were probably derived from metamorphic fluids,which had reacted with organic matter in sedimentary rocks or graphite and undergone phase separation at 1.4-1.8 kbar and 230-240℃,after peak metamorphism.It is proposed that the Hujiayu Cu deposit consists of two mineralization stages.The early stage mineralization,characterized by disseminated and veinlet copper sulfides,probably took place in an environment similar to sediment-hosted stratiform copper mineralization.Ore minerals formed in this precursor mineralization stage were remobilized and enriched in the late metamorphic hydrothermal stage,leading to the formation of thick quartz-dolomite-sulfides veins. 相似文献
9.
The Don Sixto mining area in Mendoza province, central‐western Argentina, contains an epithermal low sulfidation Au–Ag deposit. It is a small deposit (～4 km2), with a gold resource of 36 t. In Don Sixto, ore minerals are disseminated in the hydrothermal quartz veins and hydrothermally altered volcanic‐pyroclastic rock units of Permian–Triassic age. On the basis of the texture, ore mineral paragenesis and cross cutting relationship of gangue minerals, seven stages of mineralization were recognized and described. The first six stages are characterized by quartz veins with minor amounts of base metal minerals and the last stage is represented by fluorite veins with minimal quantities of base metal minerals; the precious metal mineralization is mainly related to the fourth stage. The hydrothermal veins exhibit mainly massive, crustiform and comb infilling textures; the presence of bladed quartz replacement textures and quartz veins with adularia crystals are indicative of boiling processes in the system. Fluid inclusion and complementary stable isotope studies were performed in quartz, fluorite, and pyrite samples from the vein systems. The microthermometric data were obtained from primary, biphasic (liquid‐vapor) fluid inclusion assemblages in quartz and fluorite. The maximum values for salinity and homogenization temperature (Th) came from the stage IV where quartz with petrographic evidence of boiling has average values of 4.96 wt% NaClequiv. and 286.9°C respectively. The lower values are related to the last stage of mineralization, where the fluid inclusions in fluorite have average salinities of 1.05 wt% NaClequiv. and average homogenization temperatures of 173.1°C. The oxygen and sulfur isotopic fractionation was analyzed in quartz and pyrite. The calculated isotopic fractionation for oxygen in the hydrothermal fluid is in the range of δ18OH2O = ?6.92 up to ?3.08‰, which indicates dominance of a meteoric source for the water, while sulfur reaches δ34SH2S = 1.09‰, which could be reflecting a possible magmatic, or even a mixed source. 相似文献
10.
11.
Samira Mokhtari Asl Mohammadreza Jafari Reza Zarei Sahamiyeh Vahid Shahrokhi 《Arabian Journal of Geosciences》2015,8(9):7125-7139
Farsesh barite in the central part of Iranian Sanandaj-Sirjan zone is a sample of epigenetic hydrothermal mineralization in dolomitized limestone, which provides appropriate chemicophysical conditions making the passage of mineral-bearing fluids possible. Barite veins may range from a few centimeters to 2 m in thickness that increases downward. The microthermometry measurements obtained from more than 30 fluid inclusions show relative homogenization temperatures ranging from 125 to 200 °C with an average of 110 °C for Farsesh barite deposits. The mean salinity measured proves 16 times as much as weight percentage of NaCl for barite. Coexistence of liquid- and vapor-rich fluid inclusions in barite minerals may provide an evidence of boiling in ore veins. Moreover, occurrence of bladed calcite, high-grade ore zones, and presence of hydrothermal breccia are all consistent with boiling. Thermometric studies indicate that homogenization temperatures (Th) for primary and pseudosecondary fluid inclusions in barite range from 125 to 200 °C with an average of 1,100 °C. The δ34S values of barite also lie between 8.88 and 16.6 %. The relatively narrow spread in δ34S values may suggest uniform environmental conditions throughout the mineralization field. Thus, δ34S values are lower than those of contemporaneous seawater, which indicates a contribution of magmatic sulfur to the ore-forming solution. Barite is marked by total amounts of rare Earth elements (REEs) (6.25–17.39 ppm). Moreover, chondrite-normalized REE patterns of barite indicate a fractionation of light REEs (i.e., LREEs) from La to Sm, similar to those for barite from different origins. The LaCN/LuCN ratios and chondrite-normalized REE patterns reveal that barite in Farsesh deposit is enriched in LREEs compared with heavy rare Earth elements (HREEs). Similarity between Ce/La ratios in barite samples and those found in deep-sea barite supports its marine origin. Lanthanum and Gd exhibit positive anomalies, which are common features of chemical marine sediments. Cerium shows a negative anomaly in most samples inherited from the negative Ce anomaly of hydrothermal fluid that is mixed with seawater at barite precipitation. The available data including tectonic setting, host rock characteristics, REE geochemistry, and sulfur isotopic compositions may support a hydrothermal submarine origin for Farsesh barite deposit. 相似文献
12.
XU Hai GAO Junbo YANG Ruidong DU Lijuan LIU Zhichen CHEN Jun FENG Kangning YANG Guanghai 《《地质学报》英文版》2020,94(1):90-102
The Zunyi manganese deposits, which formed during the Middle to Late Permian period and are located in northern Guizhou and adjacent areas, are the core area of a series of large-medium scale manganese enrichment minerogenesis in the southern margin and interior of the Yangtze platform, Southern China. This study reports the universal enrichment of rare earth elements(REEs) in Zunyi manganese deposits and examines the enrichment characteristics, metallogenic environment and genesis of REEs. The manganese ore bodies present stratiform or stratoid in shape, hosted in the silicon–mud–limestones of the Late Permian Maokou Formation. The manganese ores generally present lamellar, massive, banded and brecciated structures, and mainly consist of rhodochrosite, ropperite, tetalite, capillitite, as well as contains paragenetic gangue minerals including pyrite, chalcopyrite, rutile, barite, tuffaceous clay rock, etc. The manganese ores have higher ΣREE contents range from 158 to 1138.9 ppm(average 509.54 ppm). In addition, the ΣREE contents of tuffaceous clay rock in ore beds vary from 1032.2 to 1824.5 ppm(average 1396.42 ppm). The REEs from manganese deposits are characterized by La, Ce, Nd and Y enriched, and existing in the form of independent minerals(e.g., monazite and xenotime), indicating Zunyi manganese deposits enriched in light rare earth elements(LREE). The Ce_(anom) ratios(average-0.13) and lithofacies and paleogeography characteristics indicate that Zunyi manganese deposits were formed in a weak oxidation-reduction environment. The(La/Yb)_(ch), Y/Ho,(La/Nd)_N,(Dy/Yb)_N, Ce/Ce* and Eu/Eu* values of samples from the Zunyi manganese deposits are 5.53–56.92, 18–39, 1.42–3.15, 0.55–2.20, 0.21–1.76 and 0.48–0.86, respectively, indicating a hydrothermal origin for the manganese mineralization and REEs enrichment. The δ~(13) C_(V-PDB)(-0.54 to-18.1‰) and δ~(18) O_(SMOW)(21.6 to 26.0‰) characteristics of manganese ores reveal a mixed source of magmatic and organic matter. Moreover, the manganese ore, tuffaceous clay rock and Emeishan basalt have extremely similar REE fractionation characteristic, suggesting REEs enrichment and manganese mineralization have been mainly origin from hydrothermal fluids. 相似文献
13.
We studied calcite and rhodochrosite from exploratory drill cores (TH‐4 and TH‐6) near the Toyoha deposit, southwestern Hokkaido, Japan, from the aspect of stable isotope geochemistry, together with measuring the homogenization temperatures of fluid inclusions. The alteration observed in the drill cores is classified into four zones: ore mineralized zone, mixed‐layer minerals zone, kaolin minerals zone, and propylitic zone. Calcite is widespread in all the zones except for the kaolin minerals zone. The occurrence of rhodochrosite is restricted in the ore mineralized zone associated with Fe, Mn‐rich chlorite and sulfides, the mineral assemblage of which is basically equivalent to that in the Toyoha veins. The measured δ18OSMOW and δ13CPDB values of calcite scatter in the relatively narrow ranges from ?2 to 5‰ and from ?9 to ?5‰, respectively; those of rhodochrosite from 3 to 9‰ and from ?9 to ?5‰, excluding some data with large deviations. The variation of the isotopic compositions with temperature and depth could be explained by a mixing process between a heated surface meteoric water (100°C δ18O =?12‰, δ13C =?10‰) and a deep high temperature water (300°C, δ18O =?5‰, δ13C =?4‰). Boiling was less effective in isotopic fractionation than that of mixing. The plots of δ18O and δ13C indicate that the carbonates precipitated from H2CO3‐dominated fluids under the conditions of pH = 6–7 and T = 200–300°C. The sequential precipitation from calcite to rhodochrosite in a vein brought about the disequilibrium isotopic fractionation between the two minerals. The hydrothermal fluids circulated during the precipitation of carbonates in TH‐4 and TH‐6 are similar in origin to the ore‐forming fluids pertaining to the formation of veins in the Toyoha deposit. 相似文献
14.
The Quebrada Marquesa Quadrangle in Chile exhibits a series of mineralizations comprising manto-type manganese and copper
deposits of Lower Cretaceous age, and copper and silver veins of Tertiary age. The deposits are hosted by volcanic and volcaniclastic
units of the Arqueros (Hauterivian-Barremian) and Quebrada Marquesa (Barremian-Albian) Formations. Three episodes of manganese
mineralization (Mn1-3) are recognized within the study area. Hydrothermal activity leading to episodes 1 and 3 was of minor importance, while the
second one (Mn2) gave rise to major manto-type deposits of both manganese and copper in the Talcuna mining district. Extensional faulting
during Tertiary time resulted in block faulting and the unroofing of the oldest andesitic volcanics and marine sediments (Arqueros
Formation). This episode was accompanied by magmatic and hydrothermal activity leading to vein formation in the Arqueros (Ag)
and Talcuna (Cu) districts. The latter veins cross-cut the previous manto-type copper deposits. Ore mineralogy is similar
in both styles of mineralization (manto- and vein-type) and consists mainly of chalcopyrite and bornite, with variable amounts
of galena, tetrahedrite (vein-related), chalcocite, sphalerite, pyrite, hematite, digenite and covellite. Alteration processes
at Talcuna can be divided into two categories, those related to the Lower Cretaceous manto-type episode (LK alteration: chlorite-epidote-calcite-albite, prehnite, zeolite), and those associated with the locally mineralized normal faults of
Tertiary age (Tt alteration: chlorite-calcite, sericite). The Arqueros silver veins display an ore mineralogy consisting of arquerite, argentite, native
silver, polybasite, cerargyrite and pyrargyrite-proustite; associated alteration includes strong chloritization of the country
rock. The manto-type deposits formed from fluids of salinity between 11 and 19 wt.% NaCl equivalent and temperatures between
120 and 205 °C. Mineralizing fluids during the vein-type stage circulated at lower temperatures, between 70 and 170 °C, with
salinity values in a wide range from 3 to 27 wt.% NaCl equivalent. This distribution of salinities is interpreted as the result
of the complex interplay of two different processes: boiling and fluid mixing; the former is considered to control the major
mineralogical, textural and fluid inclusion features of the vein-type deposits. We suggest that the Lower Cretaceous mineralization
(manto-type stage) developed in response to widespread hydrothermal activity (geothermal field-type) involving basinal brines.
Received: 18 July 1997 / Accepted: 28 January 1998 相似文献
15.
Evolution of Yanliao aulacogen in the Paleo-Mesoproterozoic and its control on manganese deposit 
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下载免费PDF全文 It is found that the bottom of Sangshu'an subgroup,which belongs to the Mesoproterozoic Gaoyuzhuang Formation located at the Yanliao aulacogen,is rich in manganese. Although there are still different viewpoints on the origin of manganese and the formation environment of manganese deposits,most scholars believe that the manganese is closely related with the extensive rifting background of the Yanliao aulacogen. In this paper,based on the analysis of exploration data on many manganese ores,the Qinjiayu manganese deposit located at Qianxi belonging to the Yanliao aulacogen,is selected. The manganese ore characteristics,ore types,and element geochemistry are analyzed. The results show that manganese mainly comes from submarine hydrothermal fluids. By analyzing the relationship between the distribution of main manganese deposits and the tectonic faults in the Yanliao aulacogen,it is found that the manganese ore of Gaoyuzhuang formation mainly concentrates at the intersections of the northeast-trending main fault and the northwest-trending transverse fault,and the relatively blocked,deep-water stagnant environment surrounded by faults,where the ore layers are thick and show a relatively high grade. It shows that the structure of the Yanliao aulacogen plays an important role in controlling the formation of Gaoyuzhuang manganese deposits. The syn-depositional faults act as channels for hydrothermal activity,providing a major source of minerals for the manganese-forming basins. 相似文献
16.
燕辽坳拉槽中元古界高于庄组桑树鞍亚组底部为锰富集层段,虽然对于锰质来源、锰矿成因及形成环境存在认识分歧,但多数学者均认为高于庄组锰矿的形成与燕辽坳拉槽的盆地裂谷背景有着密不可分的联系。在搜集前人锰矿勘查资料的基础上,重点对典型锰矿床——迁西秦家峪锰矿进行了矿床地质特征、矿石类型及元素地球化学分析,结果显示其锰质主要来源于海底热液。通过分析主要锰矿点分布与燕辽裂谷盆地主要断裂之间的关系,发现在裂谷盆地内北东向主断裂与北西向传递断裂的交汇处,或被断裂所围限的闭塞、深水滞流环境,是高于庄组锰矿形成的最有利部位,矿层厚度大,品位相对较高。该研究表明燕辽坳拉槽裂谷盆地结构对高于庄组锰矿的形成具有重要的控制作用,且同沉积断裂作为热液活动的通道,为成锰盆地提供了主要的矿质来源。 相似文献
17.
There are 10 types of tungsten ore deposits in South China: granite, porphyry, volcanic, pegmatite, skarn, greisen, wolframite-quartz ± microcline veins, stratabound, ferberite-quartz veins and placer. Most are chronologically related to Yenshanian granites. Integrated field, mineralogic, fluid inclusion and geochemical studies were undertaken to determine the characteristics and origin of the ores. Most of the tungsten ore deposits are also spatially related to Yenshanian granites. These granites include several intrusions, isotopically dated at 160–180 m. y. and 70–100 m. y. The concentration of trace elements, especially W Mo, Sn, Ta, Nb, Li, and F are relatively high in the granites. In the granites of South China, the average WO3 is 4.35 ppm, but in Yenshanian granites, which are the youngest of these, the average WO3 is 5.16 ppm. In the youngest of Yenshanian granites, a light mica-albite granite has been identified, whose average WO3 is as high as 242.3 ppm. From this line of evidence, the tungsten ore deposits in South China are considered to be genetically related to Yenshanian granites. Wolframite-sulfide-quartz veins and scheelite skarns provide the bulk of the reserves and production. There are many different kinds of alteration associated with the different tungsten ore deposits, but the principal ones are silicification, greisenization, potash-feldspathization and chloritization. Four types of fluid inclusions were found:
- Liquid-rich;
- Gas-rich;
- Liquid CO2-bearing;
- Polyphase with daughter minerals.
18.
Takeru Moriyama Mruganka K. Panigrahi Dinesh Pandit Yasushi Watanabe 《Resource Geology》2008,58(4):402-413
The major, trace and rare earth element (REE) composition of Late Archean manganese, ferromanganese and iron ores from the Iron Ore Group (IOG) in Orissa, east India, was examined. Manganese deposits, occurring above the iron formations of the IOG, display massive, rhythmically laminated or botryoidal textures. The ores are composed primarily of iron and manganese, and are low in other major and trace elements such as SiO2, Al2O3, P2O5 and Zr. The total REE concentration is as high as 975 ppm in manganese ores, whereas concentrations as high as 345 ppm and 211 ppm are found in ferromanganese and iron ores, respectively. Heavy REE (HREE) enrichments, negative Ce anomalies and positive Eu anomalies were observed in post‐Archean average shale (PAAS)‐normalized REE patterns of the IOG manganese and ferromanganese ores. The stratiform or stratabound shapes of ore bodies within the shale horizon, and REE geochemistry, suggest that the manganese and ferromanganese ores of the IOG were formed by iron and/or manganese precipitation from a submarine, hydrothermal solution under oxic conditions that occurred as a result of mixing with oxic seawater. While HREE concentrations in the Late Archean manganese and ferromanganese ores in the IOG are slightly less than those of the Phanerozoic ferromanganese ores in Japan, HREE resources in the IOG manganese deposits appear to be two orders of magnitude higher because of the large size of the deposits. Although a reliable, economic concentration technique for HREE from manganese and ferromanganese ores has not yet been developed, those ores could be an important future source of HREE. 相似文献
19.
The Kalahari Goldridge Mine is located within the Archaean Kraaipan Greenstone Belt, about 60 km southwest of Mafikeng in the North West Province, South Africa. The ore body thickness varies from 15 to 45 m along a strike length of about 1.5 km within approximately N–S striking banded iron formation (BIF). The stratabound ore body is hosted primarily by BIF, which consists of alternating chert and magnetite–chlorite–stilpnomelane–sulphide–carbonate bands of millimetre- to centimetre scale. A footwall of sericite–carbonate–chlorite schist underlain by mafic amphibolite occurs to the west and carbonaceous metapelites in the hanging wall to the east. Overlying the hanging wall, carbonaceous metapelites, units of coarse-grained metagreywackes fining upwards, become increasingly conglomeratic up the stratigraphy. Small-scale isoclinal folds, brecciation, extension fractures and boudinage of cherty BIF units reflect brittle-ductile deformation. Fold axial planes have foliation, with subvertical plunges parallel to prominent rodding and mineral lineation in the footwall rocks. Gold mineralisation is associated with two generations of quartz–carbonate veins, dipping approximately 20° to 40° W. The first generation consists of ladder-vein sets (group IIA) preferentially developed in centimetre-scale Fe-rich mesobands, whereas the second generation consists of large quartz–carbonate veins (group IIB), which locally crosscut the entire ore body and extend into the footwall and hanging wall. The ore body is controlled by mesoscale isoclinal folds approximately 67° E, orthogonal to the plane of mineralised, gently dipping veins, defining the principal stretching direction and development of fluid-focussing conduits. The intersections of the mineralised veins and foliation planes of the host rock plunges approximately 08° to the north. Pervasive hydrothermal alteration is characterised by chloritisation, carbonatisation, sulphidation and K-metasomatism. Gold is closely associated with sulphides, mainly pyrite and pyrrhotite, and to a lesser extent, with bismuth tellurides and carbonate minerals. Mass balance transfer calculations indicate that hydrothermal alteration of BIF involved enrichment of Au, Ag, Bi, Te, S and CO2 (LOI), MgO, Ba, K and Rb, but significant depletion of SiO2 and, to a lesser extent, Fe2O3. Extensive replacement of magnetite and chlorite in BIF and other pelitic sedimentary rocks by sulphide and carbonate minerals, both on mesoscopic and microscopic scales, is evidence of interaction of CO2- and H2S-bearing fluids with the Fe-rich host rocks. The fineness of gold grains ranges from 823 to 921, similar to that of other epigenetic Archaean BIF-hosted gold deposits, worldwide. 相似文献
20.
隐伏矿床上方纳米铜颗粒存在形式与成因 总被引：3，自引：0，他引：3
在铜镍矿床覆盖层土壤颗粒中和其下伏原生矿石中同时采集到金属纳米颗粒,颗粒在其粒径大小、形貌、连接和簇聚形式、微粒元素组合等性质上相似,表明两者为同成因物质,是内生成矿作用元素存在形式,土壤颗粒中金属纳米颗粒来自深部矿体。在金矿上方土壤颗粒中采集的纳米金属颗粒,与在铜镍矿床覆盖层土壤颗粒中采集观测到的微粒,在微粒性质可以对比,表明元素的纳米微粒是稳定形式,在其源区形成后可借助多种营力,穿越后期地质作用覆盖层,在近地表被土壤地球化学障捕获滞留,是深部矿化的有效传递物质。深穿透地球化学技术可从土壤中分离富集采集到此纳米微粒,并通过其微粒性质,追踪其源区性质。此研究结果在实用意义上,可为以土壤作为采样介质的深穿透地球化学勘查探测覆盖区隐伏矿方法提供理论依据。 相似文献