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1.
Organic carbon isotope composition was studied in the sedimentary cover of the southern Siberian Platform and its surrounding fold systems. The rocks experienced catagenesis, metamorphism, and metasomatism. The chloroform bitumoid (CB) has a stable carbon isotope composition within a wide range of postsedimentation transformations. The average values of δ13C in CB of the sedimentary cover are ?29.5‰. Metamorphism and, especially, ore metasomatism, at the Sukhoi Log deposit caused a 2‰ increase in the heavy carbon isotope concentration of CB as compared to that of the platform deposits. The narrow variations in carbon isotope composition of the bitumoid are defined by their derivation from lipids, whose components are almost insusceptible to changes in the PT conditions. Kerogen from platform deposits is more strongly depleted than CB in the heavy carbon isotope (δ13Cav ? 32.2‰). The insoluble carbonaceous matter (ICM) of the metamorphic shales is significantly enriched in the heavy carbon isotope (δ13Cav ? 21.9‰). The highest changes in carbon isotope composition were found in concentrates of ICM from metasomatically altered rocks of the Sukhoi Log deposit (δ13Cav ? 17.5‰). The heavier carbon isotope composition caused by metamorphism and metasomatism is evidently defined by isotopic exchange between the carbonate carbon and CO2 of metasomatic solutions, on one hand, and ICM of shales, on the other. 相似文献
2.
青龙—阜新构造岩浆成矿带,展布2类5型中生代花岗岩27处,分5次侵入,燕山期第2序Ⅰ型细粒二长花岗岩与成矿直接有关。两大矿源层——建平群中的钼铜金硫和长城系中的铅锌锰铁。壳源重熔花岗岩浆以多种方式将多源成矿物质汇集成多种类型的多金属矿床,在空间上形成紧密共生有规律展布的花岗岩成矿系列。在水平方向上以花岗岩体为中心划分出四个成矿带和相应的三套围岩蚀变组合。火山机构中由下而上呈现两层楼成矿模式。 相似文献
3.
《地学前缘(英文版)》2016,7(3)
The Chertovo Koryto gold deposit(80 t Au at 1.84 g/t) in the Lena world-class province,Siberia,is hosted in a metamorphosed sequence of the Paleoproterozoic Mikhailovsk Formation that comprises the oldest black shale strata of the Baikal-Patom region.The mineralisation is confined to the thrust zone complicated with a conjugate anticline fold,zones of shearing and dislocation.The struaural position of the mineralisation is similar to that at the giant Sukhoi Log deposit in the neighbouring Mama-Bodaibo zone.In the latter,the isotope age data suggest that Khomolkho black shales,hosts to Sukhoi Log mineralisation,are of Ediacaran age and underwent prograde metamorphism during early Paleozoic.The geochemical composition of the terrigenous rocks that host Sukhoi Log,Chertovo Koryto,and a number of other deposits at the various stratigraphic levels throughout the Proterozoic sequence have much in common.They do not show elevated metal contents above the common black shale abundances,except for Au and As,which is at variance with the accepted view on diagenetic enrichment of black shales in the Lena province.The occurrence of sagenitic rutile in quartz and chlorite pseudomorphs after biotite and other petrographic observations provide evidence on a retrograde nature of the metamorphic mineral assemblages in the Mikhailovsk rocks.The sulphides are pyrrhotite and arsenopyrite with very minor pyrite at Chertovo Koryto,whereas pyrite is the predominant sulphide in the Sukhoi Log ore.Fluid inclusion data on both deposits emphasise a high-temperature nature of the mineralisation albeit revealing great contrast in the fluid composition.Sukhoi Log mineralisation was formed at mixing between low-salinity aqueous solutions and dense gaseous carbonic fluids,which facilitated effective gold scavenging and precipitation,as demonstrated by thermodynamic simulation.The precursory devolatilisation of the Mikhailovsk sediments at the prograde stage results in the paucity of gaseous carbonic fluid during retrograde metamorphism and mineralisation.The similarity in the styles and chemical parameters of mineralisation,and the predominant structural control of ore localisation within the same Precambrian regional tectonic unit support an idea that orogenic gold mineralisation in the Lena province was produced during a single early Paleozoic event. 相似文献
4.
The mixing of gas and aqueous fluid in hydrothermal ore-forming processes is discussed with reference to gold deposits to demonstrate that this phenomenon may affect ore deposition. Data on fluid inclusions in samples from the Sukhoi Log and Olimpiadinskoe deposits in Russia are utilized to demonstrate possible implications of gas mixing with hydrothermal solution when gold ores are formed. A simplified thermodynamic model is suggested to show how interaction between aqueous saline solutions with pure carbon dioxide or carbon dioxide—methane mixture may affect gold solubility. Further studying such processes may provide interesting information for understanding the genesis of ore mineralization. 相似文献
5.
I. V. Chernyshev A. V. Chugaev Yu. G. Safonov M. R. Saroyan M. A. Yudovskaya A. V. Eremina 《Geology of Ore Deposits》2009,51(6):496-504
The lead isotopic composition of 33 sulfide samples from orebodies of the Sukhoi Log deposit was studied by high-precession
MC-ICP-MS with a precision of ±0.02% (±2SD from 120 analyses of the SRM 981 standard sample). The deposit is located in the
Bodaibo gold mining district in the northern Baikal-Patom Highland. Gold mineralization is hosted in Neoproterosoic black
slates. Variations of lead isotope ratios of the Sukhoi Log sulfides are generally typical of Phanerozoic deposits and ore
fields. They are significant for 206Pb/204Pb (17.903–18.674), moderate for 208Pb/204Pb (37.822–38.457), and relatively narrow for 207Pb/204Pb (15.555–15.679). In the Pb-Pb isotope diagrams, the data points of pyrite and galena constitute a linear trend. The points
corresponding to pyrite from metasomatic ore occupy the left lower part of the trend. Galena from late gold-quartz veins shows
more radiogenic Pb, and corresponding data points are located in the upper part of the trend. According to the Stacey-Kramers
model, the end points of the trend, which is regarded as a mixing line, have μ2 = 9.6 and μ2 = 13.2 and model Pb-Pb ages 455 and 130 Ma, respectively. The isotope characteristics of ore lead, their relationships in
pyrite and galena, and the mixing trend of Pb isotopic compositions are clearly tied to two Paleozoic stages in the formation
of the Sukhoi Log deposit (447 ± 6 and 321 ± 14Ma) and testify to the leading role of crustal sources, which are suggested
as being the Neoproterozoic black-shale terrigenous-carbonate rocks. 相似文献
6.
碱型地幔流体与富碱热液成矿 总被引：10，自引：1，他引：9
碱交代作用是整个热液作用成矿的一个基本机理,包括:①所有的热液作用是碱型地幔流体从对岩石(或岩体或地层)进行碱交代(K、Na的带入)开始的;②提供矿源(靠富K、Na热液的强烈交代作用在热液上升路途中萃取岩石矿质);③形成碱交代岩,使热液由强碱性向酸性([H+]离子浓度增长)演化,以破坏稳定的矿质迁移形式,导致沉淀、卸载、成矿;④碱交代岩是高压高温爆裂岩,角砾和次生孔隙度由此大增,有利于热液和构造再活动,成为金属成矿和油气成藏的有利储矿围岩.文章用新的证据证明此富碱热液来自深部碱型地幔流体(A-HA00NS).通过碱金属地球化学这条纲把热液作用和地幔流体作用串联为深浅一个整体. 相似文献
7.
8.
A review of previous studies of the world's large hydrothermal gold deposits indicates that the largest deposits tend to show complicated parageneses where multiple gold enrichment events and processes have been involved in the deposit generation. These observations suggest that multistage processes may even be a requirement for the formation of large deposits. In some deposits (e.g. Witwatersrand, Boddington Cadia, Sukhoi Log or Carlin) the different enrichment processes occur millions of years apart. In others, such as many large porphyry deposits, the different stages are much closer in time. In many deposits, particularly sedimentary-hosted deposits, early diffuse enrichment occurs within a particular province that is then upgraded by more focused processes (e.g., Sukhoi Log; Kalgoorlie). The presence of this early diffuse enrichment could explain the tendency for gold deposits to cluster into camps.This model has important implications, as the presence or absence of multiple gold events could be used to discriminate, at the exploration and feasibility stages, between small deposits with single stage ore genesis and more complicated deposits with multistage enrichment and the potential for larger gold endowment. 相似文献
9.
T. A. Ikonnikova E. O. Dubinina M. R. Saroyan A. V. Chugaev 《Geology of Ore Deposits》2009,51(6):505-512
The relationships between the δ18O of quartz veins and veinlets pertaining to the main stage of gold mineralization at the Sukhoi Log deposit and metasomatically
altered host slates are estimated. The oxygen isotopic composition of veined quartz and host slates is not uniform. The δ18O of quartz veins from the Western, Central, and Sukhoi Log areas of the deposit vary from +16 to + 18 ‰. The δ18O range of metasomatically altered slates in the Western and Sukhoi Log areas attains 6 ‰. The δ18O of quartz veins are always higher than those of host slates by 3–7‰. The regular difference in the δ18O between quartz veins and host slates indicates that the oxygen isotopic composition of the ore-bearing fluid forming the
system of quartz veins and veinlets at the Sukhoi Log deposit could have formed as a result of interaction with silicate rocks,
for instance, terrigenous slates enriched in δ18O. Such interaction, however, took place at deeper levels of the Sukhoi Log deposit. It is suggested that the fluid phase
participating in the formation of the vein and veinlet system had initially high δ18O(>+10‰) due to interaction with the rocks enriched in δ18O at a low fluid/rock ratio. The oxygen isotope data indicate that the fluid participating in the formation of gold mineralization
at the Sukhoi Log deposit was not in equilibrium with igneous rocks at high temperatures. 相似文献
10.
贺兰山北段牛头沟金矿床为华北克拉通西北缘新发现的金矿床,包括构造破碎带蚀变岩型和石英脉型两种矿化类型,后者可进一步细分为低缓石英脉型和陡窄石英脉型2个亚类。矿区所有矿体均赋存在古元古界贺兰山群变质杂岩和混合花岗岩内,受主干断裂F_1及其上盘次级断裂体系控制。综合本文及前人研究成果表明,破碎带蚀变岩型石英流体包裹体以纯液相水溶液包裹体为主,而低缓石英脉型和陡窄石英脉型石英流体包裹体则以气液两相水溶液包裹体为主,不同矿化类型成矿流体均为中低温(160~210℃)、中低盐度(6%~12%NaCl_(eq))的H_2O-NaCl流体。对矿区内3种矿化类型石英流体包裹体和硫化物分别开展的H-O和S-Pb同位素研究显示:破碎带蚀变岩型和陡窄石英脉型流体包裹体δD_(H2O)组成相近,分别为-75.2‰~-89.3‰和-87.0‰~-93.8‰,而低缓石英脉型流体包裹体则具有较高的δD_(H2O)值(-45.7‰~-67.7‰);流体包裹体δ~(18)O_(H2O)值则由破碎带蚀变岩型(3.7‰~4.4‰)→低缓石英脉型(1.9‰~3.3‰)→陡窄石英脉型(0.5‰~0.9‰)依次降低。破碎带蚀变岩型和陡窄石英脉型δ~(34)S组成均为正值,分别为1.3‰~6.9‰和2.2‰~5.8‰,而低缓石英脉型则具有较低的δ~(34)S值(-5.1‰~-2.6‰)。低缓石英脉型金矿具有明显不同的δD_(H2O)和δ~(34)S组成,可能与含矿断裂性质及其距离导矿构造F_1断裂较远等因素所共同导致的成矿流体氧逸度升高有关。3种矿化类型对应的矿石均表现出明显富集Th放射成因Pb的特点,~(206)Pb/~(204)Pb(16.467~17.994)和~(207)Pb/~(204)Pb(15.382~15.582)组成相对均一,而~(208)Pb/~(204)Pb变化较大(37.413~42.345)。总体上,石英流体包裹体H-O同位素组成表明成矿流体均为岩浆水和大气降水形成的混合流体,其大气降水比例自破碎带蚀变岩型→低缓石英脉型→陡窄石英脉型依次升高;矿石S-Pb同位素指示成矿物质为深部岩浆和具有高Th/U比的基底围岩双重来源。结合区域构造–岩浆演化,笔者将牛头沟金矿床成矿过程概括为晚古生代裂陷盆地形成阶段、中晚侏罗世区域挤压推覆阶段和晚侏罗世至早白垩世岩浆热液活动阶段等3个阶段。 相似文献
11.
位于右江盆地南部的滇东南底圩金矿床是近年来新发现的一处金矿床,为理清其成因,对不同类型矿石和赋矿围岩进行了主、微量元素及硫化物的硫同位素分析.结果表明,相较于赋矿围岩,矿石中明显富集Au、As、Sb、Hg、Tl、S、K、C元素,应为热液带入;而Si、Mg、Fe、Zr 和Th在矿石和围岩中变化不大,Fe主要来源于赋矿围岩... 相似文献
12.
E. O. Dubinina A. V. Chugaev T. A. Ikonnikova A. S. Avdeenko A. I. Yakushev 《Petrology》2014,22(4):329-358
Complex (δ18O, δ13C, 87Sr/86Sr, 143Nd/144Nd, and REE composition) data were obtained on quartz-carbonate veins in metasedimentary rocks to elucidate the material sources and to evaluate fluid regime during low-sulfide gold-quartz ore mineralization at the Sukhoi Log deposit. In order to use an oxygen isotopic thermometry for quartz veins, we calibrated empirical dependence of fractionation factors between vein quartz and altered wall rocks. The temperature range of quartz equilibration with wall rocks was evaluated at 380–190°C. Independent temperatures obtained using this thermometer indicate that the vein ankerite can be both earlier and later than vein quartz. The isotopic systematics (δ13C and δ18O) of ankerite in the quartz-carbonate veins, carbonates in the ore-hosting shales of the Khomolkho and Imnyakh formations both within and outside mineralized zones at the deposit indicate that the ore-hosting rocks and veins in the mineralized zone contain incoming carbonate, which was most probably borrowed from the carbonate rocks of the Imnyakh Formation. REE composition of vein ankerite shows that these elements were transported by fluid as carbonate complexes. The behavior of the Eu/Eu* and (La/Yb)n ratios and Mn of the vein ankerite suggest that during carbonate crystallization the system was closed with respect to fluid. Sr-Nd isotope systematics indicates that the isotopic parameters of the vein ankerite were formed with the participation of metasedimentary host rocks of both the Imnyakh and Khomolkho formations, which are contrastingly different in Nd isotopic composition. A fluid/rock ratio during metasomatic processes in the wall rocks was calculated for two scenarios of their thermal history: with a continuously operating heat source beneath the Sukhoi Log structure and with a linear cooling of the structure. The effective integral W/R ratios calculated lie within the range of 0.046–0.226 and suggest that the veins were produced with the metamorphic fluid. Low W/R ratios are inconsistent with the mechanism of vein quartz crystallization due to fluid oversaturation with respect to SiO2 at decreasing temperature. We believe that the main mechanism responsible for the origin of these veins was variations of fluid oversaturation due to pressure variations (pressure solution mechanism). This hypothesis is consistent with the reported isotopic-geochemical characteristics of the wall rocks at the Sukhoi Log deposit. 相似文献
13.
Robin Bernau Stephen Roberts Mike Richards Bruce Nisbet Adrian Boyce James Nowecki 《Mineralium Deposita》2013,48(2):137-153
The Lumwana Cu (± Co ± U) deposits of NW Zambia are large, tabular, disseminated ore bodies, hosted within the Mwombezhi Dome of the Lufilian Arc. The host rocks to the Lumwana deposits are two mineralogically similar but texturally distinct gneisses, a granitic to pegmatitic gneiss and a banded to augen gneiss which both comprise quartz–feldspar ± biotite ± muscovite ± haematite ± amphibole and intervening quartz–feldspar ± biotite schist. The sulphide ore horizons are typically developed within a biotite–muscovite–quartz–kyanite schist, although mineralization locally occurs within internal gneiss units. Contacts between the ore and host rocks are transitional and characterized by a loss of feldspar. Kinematic indicators, such as S-C fabrics and pressure shadows on porphyroblasts, suggest a top to the north shear sense. The sulphides are deformed by a strong shear fabric, enclosed within kyanite or concentrated into low strain zones and pressure shadows around kyanite porphyroblasts. This suggests that the copper mineralization was introduced either syn- or pre-peak metamorphism. In addition to Cu and Co, the ores are also characterized by enrichments in U, V, Ni, Ba and S and small, discrete zones of uranium mineralization, occur adjacent to the hanging wall and footwall of the copper ore bodies or in the immediate footwall to the copper mineralization. Unlike typical Copperbelt mineralization, unmineralized units show very low background copper values. Whole rock geochemical analyses of the interlayered schist and ore schist, compared to the gneiss, show depletions in Ca, Na and Sr and enrichments in Mg and K, consistent with replacement of feldspar by biotite. The mineral chemistry of muscovite, biotite and chlorite reflect changes in the bulk rock chemistry and show consistent increases in X Mg as the schists develop. δ34S for copper sulphides range from +2.3?‰ to +18.5?‰, with pyrite typically restricted to values between +3.9?‰ and +6.2?‰. These values are atypical of sulphides precipitated by bacteriogenic sulphate reduction. δ34S data for Chimiwungo (Cu + Co) show a broader range and increased δ34S values compared to the Malundwe (Cu) mineralization. The Lumwana deposits show many characteristics which distinguish them from classical Copperbelt mineralization and which suggests that they are formed by metasomatic alteration, mineralization and shearing of pre-Katangan basement. Although this style of mineralization is reported elsewhere in the Copperbelt, sometimes associated with the more widely reported stratiform ores of the Lower Roan, none of the previously reported occurrences have so far developed the tonnages of ore reported at Lumwana. 相似文献
14.
15.
The Pb-Zn metallogenic district in NW Guizhou Province is an important part of the Yun-nan-Sichuan-Guizhou Pb-Zn metallogenic province, and also is one of the most important Pb-Zn producers in China. The hosting rocks of the Pb-Zn deposits are Devonian to Permian carbonate rocks, and the basement rocks are meta-sedimentary and igneous rocks of the Proterozoic Kunyang and Huili groups. The ore minerals are composed of sphalerite, galena and pyrite, and the gangue minerals are include calcite and dolomite. Geology and C-O isotope of these deposits were studied in this paper. The results show that δ13C and δ18O values of hydrothermal calcite, altered wall rocks-dolostone, sedimentary calcite and hosting carbonate rocks range from -5.3‰ to -0.6 ‰ (mean -3.4‰) and +11.3‰ to +20.9 ‰ (mean +17.2‰), -3.0‰ to +0.9 ‰ (mean -1.3‰) and +17.0‰ to +20.8‰ (mean +19.7‰), +0.6‰ to +2.5 ‰ (mean +1.4‰) and +23.4‰ to +26.5 ‰ (mean +24.6‰), and -1.8‰ to +3.9‰ (mean +0.7‰) and +21.0‰ to +26.8‰ (mean +22.9‰), respectively, implying that CO2 in the ore-forming fluids was mainly a result of dissolution of Devonian and Carboniferous carbonate rocks. However, it is difficult to evaluate the contribution of sediment de-hydroxylation. Based on the integrated analysis of geology, C and O isotopes, it is believed that the ore-forming fluids of these carbonate-hosted Pb-Zn deposits in this area were derived from multiple sources, including hosting carbonate rocks, Devonian to Permian sedimentary rocks and basement rocks (the Kun-yang and Huili groups). Therefore, the fluids mixing is the main precipitation mechanism of the Pb-Zn deposit in this province. 相似文献
16.
北祁连中段北缘冷龙岭铀矿带处于祁连-龙首山NW向海西碱交代热液型铀成矿带,是典型的钠交代型铀矿带。铀成矿与钠交代有着十分密切的关系,矿体几乎都产在钠交代岩内。矿床内钠交代岩矿物组成上的最大特点是原岩矿物大多消失,代之以红色的钠长石。钠交代使岩石有效孔隙度增大,并且降低了抗压强度,从而成为构造活动的薄弱环节。钠交代促使原岩中铀的赋存状态发生改变,使铀发生活化转移。在钠质交代过程中,许多铀元素的载体矿物被钠长石交代,也是使铀发生活化转移的重要因素。以上事实充分说明,钠交代不仅为铀沉淀提供了良好的空间,而且为铀成矿奠定了物质基础。 相似文献
17.
V. A. Koroteev V. N. Sazonov V. N. Ogorodnikov Yu. A. Polenov 《Geology of Ore Deposits》2009,51(2):93-108
Rift-related (1.2 Ga) and collision (380–240 Ma) suture zones of the Urals are described. The riftrelated suture zones comprise an ultramafic-gabbro complex with titanomagnetite mineralization, an ultramafic complex with chromite mineralization, and a complex of alkali granitoids with rare-metal (including REE) mineralization accompanied by K-feldspathites, albitites, and calcite metasomatic rocks. The collision suture zones are distinguished by early collision granitoids specialized for tungsten (scheelite) and gold, as well as by raremetal granites and such derivatives of them as pegmatite and greisen with rare-metal and colored-stone mineralization. The suture zones are characterized by long-term (up to 80 Ma or more) continuous-discontinuous periods of ore deposition; heterogeneous sources of ore matter and ore-bearing fluids; a polyelemental composition of lithogeochemical halos and an integral mineral composition of altered wall rocks; and the occurrence of mafic, intermediate, and felsic dikes at large gold deposits, as well as wide variations in PT parameters of the ore-forming process: T = 620?150°C and P = 3.2?0.6 kbar. Collision played a dual role in ore formation. On the one hand, collision led to deformation and metamorphism of precollision massive sulfide deposits and, to a lesser degree, Au-bearing Fe and Cu skarn and porphyry copper deposits, and, on the other hand, to the formation of new gold, rare-metal, quartz, colored-stone, talc, muscovite, and noble serpentine deposits. As a rule, this polygenetic mineralization differs in age and is related to collision volcanic and plutonic complexes. This diversity can be a good basis for metallogenic analysis, forecasting, and prospecting of various metallic deposits and industrial minerals. Polygenetic mineralization of various age known in suture zones is accompanied by integral lithogeochemical and metasomatic halos characterized by a continuous-discontinuous history. The complexity of ore mineralization and often nonlinear metallogeny increase the practical value of suture zones. 相似文献
18.
Multiple isotope composition (S, Pb, H, O, He, and Ar) and genetic implications for gold deposits in the Jiapigou gold belt, Northeast China 总被引：2，自引：0，他引：2
Qingdong Zeng Zaicong Wang Huaiyu He Yongbin Wang Song Zhang Jianming Liu 《Mineralium Deposita》2014,49(1):145-164
The Jiapigou gold belt (>150 t Au), one of the most important gold-producing districts in China, is located at the northeastern margin of the North China Craton. It is composed of 17 gold deposits with an average grade around 10 g/t Au. The deposits are hosted in Archean gneiss and TTG rocks, and are all in shear zones or fractures of varying orientations and magnitudes. The δ34S values of sulfide from ores are mainly between 2.7?‰ and 10?‰. The Pb isotope characteristics of ore sulfides are different from those of the Archean metamorphic rocks and Mesozoic granites and dikes, and indicate that they have different lead sources. The sulfur and lead isotope compositions imply that the ore-forming materials might originate from multiple, mainly deep sources. Fluid inclusions in pyrite have 3He/4He ratios of 0.6 to 2.5 Ra, whereas their 40Ar/36Ar ratios range from 1,444 to 9,805, indicating a dominantly mantle fluid with a negligible crustal component. δ18O values calculated from hydrothermal quartz are between ?0.2?‰ and +5.9?‰, and δD values of the fluids in the fluid inclusions in quartz are from ?70?‰ to ?96?‰. These ranges suggest dominantly magmatic water with a minor meteoric component. The noble gas isotopic data, along with the stable isotopic data, suggest that the ore-forming fluids have a dominantly mantle source with minor crustal addition. 相似文献
19.
大平沟金矿床是北阿尔金地区典型金矿床之一,矿化类型以钾长石-石英脉型和蚀变岩型为主,矿体赋存于近东西向韧性剪切带中,围岩为太古宇米兰岩群钾长变粒岩。矿石矿物以黄铁矿为主,另有少量褐铁矿和自然金等。大平沟金矿床含金石英脉中石英的δ18OVSMOW值为12.4‰~15.3‰,估算的流体δ18OH2O值介于7.4‰~10.3‰之间,石英中流体包裹体的氢同位素为-97‰~-66‰,表明成矿流体以变质流体来源为主;含金石英脉中硫化物的δ34SVCDT值为6.9‰~8.3‰,主要为壳源硫,与典型造山型金矿的硫值一致;硫化物的206Pb/204Pb值为18.310 1~19.373 9,207Pb/204Pb值为15.587 2~15.654 1,而208Pb/204Pb值为38.119 1~39.143 9,反映硫化物的铅来源具有造山带铅特征。综合分析认为,大平沟金矿床属于造山型金矿,其形成受近东西向次级断裂和韧性剪切带控制,成矿流体以变质流体为主,成矿物质来源于太古宙深变质岩。 相似文献
20.
安徽安庆铜铁矿床成因:矿床地质特征与元素地球化学约束 总被引：2，自引：0，他引：2
安庆铜铁矿床是产于长江中下游铜(金)、铁成矿带内安庆-贵池矿集区中的一典型矽卡岩矿床,矿体赋存于下三叠统南陵湖组大理岩与月山闪长岩体之间的接触带上。典型剖面系统取样分析显示,矿体与围岩在空间上具有显著的矿物组合分带与岩石化学分带特征,即靠近大理岩带发育致密块状磁铁矿矿石与团块状矽卡岩型矿石,远离大理岩带发育浸染状矽卡岩型矿石,靠近闪长岩带发育透辉石矽卡岩。从大理岩到磁铁矿体, Fe2O3T含量显著增加,之后随着靠近闪长岩体,其含量呈逐渐降低趋势;而CaO显示了与Fe2O3T相反的成分变异特征。矿物与全岩微量元素研究表明,致密块状磁铁矿矿石及团块状矽卡岩型矿石均具有岩浆成因的稀土元素配分模式;而浸染状矽卡岩型矿石显示了交代成因的稀土元素配分特征。矿体地质、矿相学与元素地球化学综合研究表明,矽卡岩成矿经历了矿浆贯入期与热液成矿期,前者包括氧化物阶段和硫化物-碳酸盐阶段,后者包括进化交代阶段、早退化蚀变阶段、石英-硫化物阶段和晚退化蚀变阶段。结合已有的区域岩浆岩成岩机制研究成果,认为安庆铜铁矿床应是矿浆贯入与接触交代复合成因的矽卡岩型矿床,由于高位岩浆房中岩浆不混溶作用形成的富Fe熔浆是该矿床中成矿元素的主要来源。 相似文献