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1.
为了探讨江西簧碧萤石矿床的成矿物质来源、成矿机理与演化,对其地质背景、萤石稀土元素地球化学特征进行了研究。研究结果表明:簧碧萤石矿中萤石稀土元素配分曲线显示为中等程度的左倾,呈较为平坦的"V"字形,且δEu负异常明显,与我国东南部中生代火成岩区的萤石矿床的稀土分布型式极其相似。根据La/Ho-Y/Ho关系图,萤石稀土元素数据投点在图中近水平展布,表明该矿区内萤石的成矿流体是同源的,可能为同一成矿流体不同成矿阶段的产物。簧碧萤石矿的成矿物质Ca元素可能主要是由岩浆期后热液对周潭岩组变质岩地层的淋滤萃取而来,F元素来源除了岩浆期后热液以外,区域上周潭岩组变质岩具富含F的黑云母,也非常有可能是F的主要来源之一。综合矿床地质特征、萤石稀土元素La/Ho-Y/Ho关系图及其Tb/Ca-Tb/La关系图,说明簧碧萤石矿为岩浆期后热液成因—断裂带充填交代型脉状萤石矿床。  相似文献   

2.
为研究滇西小龙河锡矿床和来利山锡矿床的成矿流体演化特征和矿床成因,采用等离子质谱法(ICP-MS)对2个矿床中的脉石矿物萤石和方解石进行了微量元素和稀土元素分析测试。结果表明,小龙河矿床萤石的稀土元素总量(ΣREE)为12.86×10-6~2275.96×10-6,具有弱的负Ce异常和强的负Eu异常,相对富集Rb、Th、U、Pr、Nd和Sm等元素。来利山矿床方解石的ΣREE值低,为3.18×10-6~29.16×10-6,具有弱的负Ce异常,相对富集Rb、Ba、Th、U、Sr和Eu等元素。2个矿床的Y/HoLa/Ho图解和Tb/Ca-Tb/La图解指示萤石和方解石均为热液成因。小龙河矿床成矿物质主要来源于岩浆热液,随着成矿流体的演化,后期明显带有沉积地层物质加入,而来利山矿床成矿物质主要来源于围岩地层。  相似文献   

3.
为进一步明确内蒙古喀喇沁旗地区萤石矿床的成因,为该区下一步萤石矿找矿勘查工作提供参考,在系统总结研究区萤石矿床地质特征及分布规律的基础上,通过分析典型萤石矿床围岩和萤石的微量元素及稀土元素地球化学特征,探讨萤石矿床的成因及成矿物质来源。结果表明,喀喇沁旗地区萤石矿中萤石的Cu、Pb和Zn含量较低,轻稀土元素略富集,稀土元素总量相对较低,说明该区萤石矿成矿流体为岩浆期后热液成因的可能性较小; 萤石矿与赋矿围岩的球粒陨石标准化稀土元素配分曲线相似且同步,当围岩为黑云母二长花岗岩时,萤石及围岩与华南黑云母的球粒陨石标准化稀土元素配分曲线一致,表明萤石中的稀土元素可能主要来源于被破坏了的黑云母,说明这类萤石成矿物质主要来源于地下热水流体对围岩的淋滤和萃取。结合研究区北部林西地区萤石矿床H-O、S同位素研究成果,认为喀喇沁旗地区萤石矿属于有大气降水参与的热液脉状充填型成因类型。  相似文献   

4.
为进一步明确内蒙古喀喇沁旗地区萤石矿床的成因,为该区下一步萤石矿找矿勘查工作提供参考,在系统总结研究区萤石矿床地质特征及分布规律的基础上,通过分析典型萤石矿床围岩和萤石的微量元素及稀土元素地球化学特征,探讨萤石矿床的成因及成矿物质来源。结果表明,喀喇沁旗地区萤石矿中萤石的Cu、Pb和Zn含量较低,轻稀土元素略富集,稀土元素总量相对较低,说明该区萤石矿成矿流体为岩浆期后热液成因的可能性较小;萤石矿与赋矿围岩的球粒陨石标准化稀土元素配分曲线相似且同步,当围岩为黑云母二长花岗岩时,萤石及围岩与华南黑云母的球粒陨石标准化稀土元素配分曲线一致,表明萤石中的稀土元素可能主要来源于被破坏了的黑云母,说明这类萤石成矿物质主要来源于地下热水流体对围岩的淋滤和萃取。结合研究区北部林西地区萤石矿床H-O、S同位素研究成果,认为喀喇沁旗地区萤石矿属于有大气降水参与的热液脉状充填型成因类型。  相似文献   

5.
为进一步明确内蒙古喀喇沁旗地区萤石矿床的成因,为该区下一步萤石矿找矿勘查工作提供参考,在系统总结研究区萤石矿床地质特征及分布规律的基础上,通过分析典型萤石矿床围岩和萤石的微量元素及稀土元素地球化学特征,探讨萤石矿床的成因及成矿物质来源。结果表明,喀喇沁旗地区萤石矿中萤石的Cu、Pb和Zn含量较低,轻稀土元素略富集,稀土元素总量相对较低,说明该区萤石矿成矿流体为岩浆期后热液成因的可能性较小; 萤石矿与赋矿围岩的球粒陨石标准化稀土元素配分曲线相似且同步,当围岩为黑云母二长花岗岩时,萤石及围岩与华南黑云母的球粒陨石标准化稀土元素配分曲线一致,表明萤石中的稀土元素可能主要来源于被破坏了的黑云母,说明这类萤石成矿物质主要来源于地下热水流体对围岩的淋滤和萃取。结合研究区北部林西地区萤石矿床H-O、S同位素研究成果,认为喀喇沁旗地区萤石矿属于有大气降水参与的热液脉状充填型成因类型。  相似文献   

6.
笔者总结了福建余朋—南口地区火把山萤石矿床的地质特征, 并通过萤石的微量元素及稀土元素地球化学特征, 探讨了矿床的成因及成矿物质、流体来源。萤石矿石的微量元素及稀土元素结果显示: 火把山萤石呈中等Eu负异常及弱Ce异常, 稀土元素配分模式具有轻稀土富集型及轻稀土弱亏损的平缓型等两种曲线型式。根据萤石矿石特征、微量元素、稀土元素等特征及Y/Ho-La/Ho图解, 可知萤石存在至少三期成矿地质作用。依据M?ller的Tb/La-Tb/Ca成因判别图解, 结合常口萤石矿床的萤石及围岩的稀土元素特征, 认为火把山萤石成矿流体一方面与常口大型萤石矿床受同一成矿流体场控制, 并在有利的部位富集成矿; 另一方面, 成矿热液流体流经下峰岩组发生了淋滤、萃取、交换作用, 形成了不同地球化学特征的另一成矿期次的萤石。综合分析认为, 火把山萤石矿床为受断裂控制的大气降水成因的中低温热液充填矿床。  相似文献   

7.
塔里木盆地巴楚-柯坪野外露头区和塔中井区奥陶系萤石矿体呈串珠状或沿裂缝呈条带状分布,通过露头岩心、钻井岩心、普通薄片、电子探针、X衍射、阴极发光、流体包裹体和微量元素、稳定同位素分析等方法,对萤石矿及其围岩和油藏进行详细研究,探讨萤石矿和礁滩相油藏耦合关系与成矿模式.萤石矿体富集在礁、滩相灰岩为基岩的与断层相关的部分岩溶洞穴中,和萤石一起共生的矿物还有方解石、重晶石、硬石膏、石英及黑色沥青,萤石中含丰富的液态、气态烃包裹体、固态沥青包裹体和柱条状石膏子晶;萤石的K/Rb和Sr/Ba比值远小于正常海水值,富铕及轻稀土元素而贫重稀土元素,其礁滩相围岩碳、氧同位素具越靠近萤石脉体δ13C和δ18O值负偏移越明显特征,萤石相对其围岩具有更高的87Sr/86 Sr比值.研究表明塔里木盆地奥陶系萤石矿属于“被动型”密西西比层控矿床,成矿机理为礁滩型“油气藏”转化为“矿捕”作用,具先成藏后成矿、多期成藏多期成矿特点,成矿流体具有盆地油田卤水和深循环大气淡水双重特征的后期低温热液成因性质,成矿物质来源于下寒武统下部黑色硅质岩及磷块岩,不整合面和断层是热液流体及成矿流体运移通道,生物礁滩和区域断层对萤石矿或油藏具有极其重要的“层、相、位”控制作用.  相似文献   

8.
长坑金矿地质特征与成因探讨   总被引：4，自引：0，他引：4  
通过含矿复成因角砾岩带特征，金矿物，微量元素，，稀土，硫，氢，氧稳定同位素和流体包裹体研究，确定成矿物质主要来自下石炭统碳酸盐岩，滑脱断裂叠不合面为控矿构造，矿体主要赋存在复成因角砾岩带中，成矿流体以大气水为主，矿床成因属浅成低温热液矿床。  相似文献   

9.
贵州务川-沿河地区分布大量萤石矿床(点),这些矿床(点)多与重晶石矿共生,萤石矿赋存在奥陶系桐梓组和红花园组碳酸盐岩内,矿体分布严格受地层与北西向张性断裂控制。本文选择务川涪洋地区双河、鹿坪、一碗水和通木水等萤石矿床开展稀土元素地球化学研究,结果显示,各矿床萤石稀土元素配分模式均为右倾的轻稀土富集型,且具有一定的相似性。∑REE含量分别为28.96×10-6～115.12×10-6、123.10×10-6～124.11×10-6、14.77×10-6～22.35×10-6和20.73×10-6～123.69×10-6,总体具有较强的Eu正异常、Ce负异常,表明这类萤石矿形成于较为氧化环境中。区内萤石属于北西向张性断裂和下奥陶统地层碳酸盐岩控制的中-低温热液充填交代型矿床。结合La/Ho-Y/Ho图解及矿床地质特征,本研究认为区内萤石为同一来源的成矿流体在同一成矿期次不同阶段成矿,其中双河矿床经历了多个阶段成矿叠加...  相似文献   

10.
为了探讨浙江天台盆地下陈萤石矿床的成矿机理、成矿物质来源与演化,对其地质背景、微量和稀土元素地球化学特征进行了研究。研究结果表明:天台盆地下陈萤石矿中围岩的稀土总量、轻稀土、中稀土和重稀土的含量远高于矿石。萤石、石英和围岩的稀土元素特征均为轻稀土相对富集,重稀土显示相对亏损,(La/Yb)_N通常多数大于8,配分曲线显示较陡的右倾斜。萤石的Eu均呈弱正异常,而石英则呈现弱的Eu负异常,萤石和石英的Ce基本不显异常。根据La/Ho-Y/Ho关系图,该成矿带上萤石的成矿物质是同源的,且萤石与石英为同期形成的产物。天台盆地下陈萤石矿的成矿物质Ca元素可能主要来自朝川组紫红色沉积岩,F的来源除了朝川组地层以外,陈蔡群变质岩系也应是F的主要来源之一。根据矿床地质特征及其Tb/Ca-Tb/La关系图可知,其为低温热液成因——断裂带充填交代型矿床。  相似文献   

11.
老挝班康姆矿床是近年来在琅勃拉邦-黎府成矿带新发现的一个大型铜金矿床。该矿床矽卡岩与矿体主要赋存在安山岩中且缺乏矽卡岩分带,与典型矽卡岩矿床的地质特征存在一定的差别。因此,厘清班康姆铜金矿床的成矿流体、成矿物质来源及矿床成因机制是后续开展琅勃拉邦-黎府成矿带大型铜金矿床找矿勘探的基础。该矿床矿化阶段石英流体包裹体δD分布于-110‰~-90‰,δ18O分布于-1.5‰~7.1‰,其中低δD的样品具有相对高的δ18O值;黄铁矿流体包裹体的3He/4He为0.41~3.43Ra(大部分<1Ra),40Ar/36Ar为314.8~362.4。H-O及He-Ar同位素结果表明,班康姆矿床成矿流体来源于岩浆流体(至少部分来自地幔)与低δD的大气雨水的混合,雨水占更大的比例,且某些矿化流体的雨水端元在混合前经历了明显的水岩作用。除一件样品(BK64)的黄铁矿具有高的δ34S(8.1‰)外,其余硫化物的δ34S分布于-0.9‰~1.5‰,位于地幔硫的范围。共生硫化物对的硫同位素平衡分馏计算以及动力学分馏不支持高δ34S(8.1‰)黄铁矿的硫来自从热液流体,可能来自围岩。热液方解石的δ13C范围为-3.1‰~2.5‰,δ18O变化于26.0‰~28.4‰,指示其碳来自矿区灰岩,而灰岩的溶解为热液摄取围岩的重硫提供了可能。矿石黄铁矿Pb同位素组成(206Pb/204Pb:17.9284~18.7756;207Pb/204Pb:15.5336~15.6651;208Pb/204Pb:37.9125~38.8090)位于黎府褶皱带和长山褶皱带晚二叠世—中三叠世大陆弧岩浆岩的Pb同位素范围,介于印支地块玄武岩和泰国-老挝S-型花岗岩及相关矿床的Pb同位素组成之间,指示班康姆矿床的Pb来自壳幔混合源。本文S-Pb-He-Ar同位素结果及区域Cu-Au成矿过程的岩石地化研究,表明班康姆矿床Cu、Au主要来自地幔。与典型矽卡岩Cu-Au矿床的S-Pb-H-O同位素及矽卡岩矿物流体包裹体盐度特征的对比,结合前人的火山气热液交代火山岩形成矽卡岩的实验结果,认为班康姆矽卡岩型Cu-Au矿床的形成机制为深部出溶的气相为主的含矿岩浆流体沿断裂上升到浅部交代安山岩或大理岩并经历了流体混合、沸腾及矿石沉淀等过程。  相似文献   

12.
This paper deals with characteristics of silicon isotope compositions and siliceous cathodolumines-cence of host rocks, ores and hydrothermal silicified quartz of the Carlin-type ore deposits in the Yunnan-Guizhou-Guangxi triangle area. The study shows that primary silicified quartz is nonluminescent but quartz in host rocks andsecondary silicified quartz are luminescent by the action of cathode rays. Correspondingly, silicon isotope composi-tions of host rocks, ores and hydrothermal quartz veins are clearly distinguished. In strata from the Middle Triassic tothe "Dachang" host bed, δ~(30)Si of the host rocks ranges from 0.0‰-0.3‰, while that of primary ore-forming silici-fied fluids from -0.1‰ to -0.4‰, in the Upper Permian and Lower Carboniferous strata and Indosinian diabasehost beds, δ~(30)Si of the host rocks is from -0.1‰ to -0.2‰ and that of the primary silicified quartz veins from 0.3‰-0.5‰. This pattern demonstrates the following geochemical mineralization process: primary ore-forming sili-ceous fluids migrated upwards quickly along the main passages of deep-seated faults from mantle to crust and en-tered secondary faults where gold deposits were eventually formed as a result of permeation and replacement of thesiliceous ore-forming fluids into different ore-bearing strata. This gives important evidence for the fact that ore-forming fluids of this type of gold deposits were mainly derived from upper mantle differentiation and shows goodprospects for deep gold deposits and geochemical background for large and superlarge gold deposits.  相似文献   

13.
为探讨灰家堡金矿田矿化剂和成矿物质来源,系统开展了热液方解石的稀土元素和C-O-Sr同位素研究。结果表明,热液方解石的稀土元素具有"上凸型"配分模式,低的(La/Sm)N值(0.003~0.580),较高的(Gd/Yb)N值(1.21~15.73),Eu正异常,显示成矿流体的壳源特征;产于龙潭组(P3l)的矿体中的方解石δ13CPDB为-9.3‰~1.7‰(均值为-3.93‰);产于构造蚀变体(SBT)的矿体中的方解石δ13CPDB为-7.8‰~3.3‰(均值为1.04‰),C-O同位素组成介于地幔碳酸岩与海相碳酸盐岩之间,在δ13CPDB-δ18OSMOW图解上呈近水平分布,与矿体全岩及围岩碳同位素组成相似,表明成矿流体的C可能具有多来源特征。成矿流体与围岩之间的水-岩反应并未改变矿石的碳、氧同位素组成,流体-岩石相互作用不是导致热液方解石沉淀的主要机制,而更可能与CO2的脱气作用有关;方解石的87Sr/86Sr值接近碳酸盐岩围岩、明显高于幔源物质的平均值,表明成矿热液中的Sr可能主要来自碳酸盐岩围岩。  相似文献   

14.
A comparison of ore-lead isotope ratios of Pb-Zn deposits hosted in Triassic carbonates of the Eastern and Southern Alps with the isotopic composition of trace leads of their host rocks, of Triassic volcanics, and of the underlying clastic sediments shows that these rocks could have supplied only part of the ore lead. The isotopic signature of feldspar lead from crystalline basement rocks, however, reveals that they must have contributed a significant amount of metal to these deposits. The presence of barite and of thallium is also indicative that feldspars were the main source of lead. Arsenic is one of the few important trace elements in these deposits and is known to occur in some areas of Lower Paleozoic metasediments in unusually high concentrations. Any model explaining the origin of these deposits must consider the extensive leaching of the basement and to some extent of the overlying clastic sediments as well. How the metal-bearing solutions entered the lagoonal back-reef areas is still open to question as feeder channels have not yet been positively identified. The results further demonstrate that the basement also acted as a metal source for galena-bearing deposits hosted in Permian sediments, vein-type deposits in Permian volcanics, and probably the barite-fluorite polymetallic deposits along a Devonian erosional surface in the Carnic Alps as well.  相似文献   

15.
刘敬秀 《地质科学》1998,33(3):349-358
采用分阶段加热爆裂法测定了不同成因热液矿床脉石英流体包裹体的氩同位素,计算出各温度段内大气氩的相对含量,从而,总结出大气降水热液矿床、再平衡岩浆水热液矿床等成矿流体的氩同位素组成特征及其演化规律。典型的大气降水热液矿床,其成矿流体以具有高大气Ar组分(约95%-100%)为特征;再平衡岩浆水热液矿床成矿流体的Ar同位素组成特征取决于与其有成因关系的初始岩浆水的Ar同位素组成及矿源层和围岩的性质,产于古老变质岩中的,一般以具有低大气Ar组分(约6%-20%)为特征,其它的再平衡岩浆水热液矿床在主成矿温度范围内一般为50%-60%左右。  相似文献   

16.
Although Zn–Pb deposits are one of the most important Cd reservoirs in the earth, few studies have focused on the Cd isotopic fractionation in Zn–Pb hydrothermal systems. This study investigates the causes and consequences of cadmium and sulfur isotope fractionation in a large hydrothermal system at the Tianbaoshan Zn–Pb–Cd deposit from the Sichuan–Yunnan–Guizhou (SYG) metallogenic province, SW China. Moderate variations in Cd and S isotope compositions have been measured in sphalerite cover a distance of about 78 m. Sphalerite has δ114/110Cd values ranging from 0.01 to 0.57‰, and sulfides (sphalerite, galena and chalcopyrite) have δ34SCDT values ranging from 0.2 to 5.0‰. Although δ34SCDT and δ114/110Cd values in sphalerites have no regular spatial variations, the δ34SCDT values in galena and calculated ore-forming fluid temperatures decreased from 2.1 to 0.2‰ and from about 290 to 130 °C, respectively, from the bottom to the top of the deposit. Heavy Cd isotopes are enriched in early precipitated sphalerite in contrast to previous studies. We suggest that Cd isotopic compositions in ore-forming fluids are heterogeneous, which result in heavy Cd isotope enrichment in early precipitated sphalerite. In comparison with other Zn–Pb deposits in the SYG area, the Tianbaoshan deposit has moderate Cd contents and small isotope fractionation, suggesting differences in origin to other Zn–Pb deposits in the SYG province.In the Tianbaoshan deposit, the calculated δ34S∑S-fluids value is 4.2‰, which is not only higher than the mantle-derived magmatic sulfur (0 ± 3‰), but also quite lower than those of Ediacaran marine sulfates (about 30 to 35‰). Thus, we suggest that reduced sulfur of ore-forming fluids in the deposit was mainly derived from the leaching of the basement, which contains large amount of volcanic or intrusive rocks. Based upon a combination of Cd and S isotopic systems, the Tianbaoshan deposit has different geochemical characteristics from typical Zn–Pb deposits (e.g., the Huize deposit) in SYG area, indicating the unique origin of this deposit.  相似文献   

17.
湘西北花垣矿集区位于扬子地台东南缘,是湘西-鄂西成矿带上最典型的超大型铅锌矿床所在地.通过对花垣矿集区典型铅锌矿床流体包裹体显微测温、成分分析及C、H、O同位素研究,结果表明,该区铅锌矿床闪锌矿与方解石中流体包裹体的均一温度范围集中在120~200℃,盐度范围集中在8%~20% NaCleqv.流体中液相离子成分主要为Ca2+、Na+、Mg2+、SO42-、Cl-,气相成分主要为H2O、N2和CO2及少量的CO、CH4和H2.流体的δDSMOW值范围为-60.4‰~-33.0‰,δ18O流体值范围为3.8‰~9.2‰.以上流体包裹体和稳定同位素分析结果表明,花垣矿集区铅锌矿床的成矿流体具有热卤水的性质,主要来源于建造水和大气降水.成矿期方解石的δ13CPDB值范围为-4.89‰~0.57‰,δ18OSMOW值范围为13.37‰~21.73‰,略低于碳酸盐围岩,说明成矿流体中的碳主要来源于碳酸盐围岩的溶解作用.矿石沉淀机制可能为两种流体的混合,即来自深部的富含金属物质的热卤水与富含有机质和硫酸盐的建造水及下渗大气降水的混合导致了铅锌矿石的沉淀.对地质和地球化学资料的综合结果表明,花垣矿集区铅锌矿床属于密西西比河谷型（MVT）铅锌矿床.   相似文献   

18.
Chilean manto-type (CMT) Cu(–Ag) hydrothermal deposits share a characteristic association of volcano-sedimentary Jurassic to Lower Cretaceous host rocks, style of mineralization, ore and associated mineralogy and geochemistry, with ore grades typically > 1%Cu, that make this family of deposits significant and interesting, both academically and economically. Although often stratabound, geological evidence supports an epigenetic origin for these deposits. We present a detailed stable isotope study of La Serena and Melipilla–Naltahua Lower Cretaceous deposits, central Chile, which reveals extremely negative δ34S values, to − 50‰, which are among the lowest values found in any ore deposit. In addition, the range of δ34S values from sulfides in the two areas is very wide: − 38.3 to − 6.9‰ in La Serena, and − 50.4 to − 0.6‰ in Melipilla–Naltahua. These new data significantly extended the reported range of δ34S data for CMT deposits. Co-existing sulfates range from 7.9 to 14.3‰, and are exclusive to La Serena deposit. The wide sulfide isotopic range occurs at deposit and hand specimen scale, and suggests a polygenic sulfur source for these deposits, where bacteriogenic sulfide dominates. While sulfur isotope data for the bulk of Jurassic CMT deposits, northern Chile, suggests a predominant magmatic source in their origin (mean = − 2.7 ± 1.9‰, 1σ), contributions of a magmatic component is only likely to be involved at Melipilla–Naltahua deposit.The δ13C values obtained for calcites associated with the mineralization range from − 20.1 to 0.2‰ also suggesting polygenic carbon sources, with the likely strong involvement of degradation of organic matter and leaching of limestone.Two different genetic models, with involvement of hydrocarbon, are proposed for both areas. For Melipilla–Naltahua, a two-step model can be developed as follows: 1) Framboidal pyrite growth, with very low δ34S, formed by bacterial sulfate reduction in an open system, and with diagenetic degradation of oil-related brines, leaving pyrobitumen. 2) Cu-bearing stage, replacing of framboidal pyrite, inheriting depleted sulfur as low as − 50.4‰, together with sulfides directly precipitated from a hydrothermal fluid with δ34S close to 0‰. For La Serena, a single step model fits best, without framboidal pyrite generation. Cu-bearing sulfides were precipitated mainly in veins where Cu plus base metal-bearing hydrothermal fluids mixed with H2S generated by bacterial sulfate reduction in the host rocks. Isotopic evidence clearly illustrates that bacterial activity, perhaps enhanced by hydrothermal activity, was fed by hydrocarbon brines and sulfate remobilized from continental evaporites. It is possible that variable ecological conditions led to different extents of isotopic fractionation, adding to the typical sulfur isotopic heterogeneity of such bacterial systems. For both areas, the Cu-bearing stage occurred during the peak to waning stages of the very low-grade metamorphism that affected the Lower Cretaceous sequence.  相似文献   

19.
湘西-黔东地区位于扬子陆块东南缘,在该地区碳酸盐岩地层中,目前已发现大、中、小型铅锌矿床及矿点200余处.为了解湘西-黔东地区铅锌矿床成矿作用过程,系统总结了区内主要铅锌矿床地质与地球化学特征,并对成矿机制进行探讨,建立成矿模式.区内铅锌矿床主要赋存于下寒武统碳酸盐岩中,分布明显受断裂及褶皱构造控制,矿体主要为层状、似层状或透镜状,矿物组成主要为闪锌矿、方铅矿、黄铁矿、方解石及少量萤石、重晶石和沥青,并伴随着广泛的以方解石化为主的热液蚀变.闪锌矿与方解石中的流体包裹体均一温度集中在120~200℃之间,盐度集中在8%~20%(NaCleqv)之间;成矿期方解石的δ13CPDB值范围为-4.89‰~1.50‰,δ18OSMOW值范围为13.37‰~25.09‰,略低于碳酸盐围岩;矿石硫化物δ34S值变化范围为22.3‰~36.1‰,以富含重硫为主;矿石硫化物铅同位素组成较为均一,变化范围较小,206Pb/204Pb在17.952~18.678之间,207Pb/204Pb在15.635~15.832之间,208Pb/204Pb在38.015~39.255之间.对地质和地球化学资料的综合分析表明,湘西-黔东地区铅锌矿床成矿流体为低温、中高盐度热卤水,主要来源于建造水和大气降水,成矿流体中的碳主要来源于碳酸盐围岩的溶解作用,硫来源于碳酸盐岩地层中硫酸盐热化学还原作用(TSR),铅锌主要来源于下伏地层,成矿时代为晚志留世-早泥盆世,属于比较典型的密西西比河谷型(MVT)铅锌矿床.综合以上分析建立了该地区铅锌矿床有机质参与下的多源流体混合成矿模式.   相似文献   

20.
宁芜陶村磁铁矿矿床成矿流体及成矿作用   总被引：2，自引：0，他引：2  
陶村磁铁矿矿床位于长江中下游成矿带宁芜盆地中段,矿床地质特征及岩浆构造背景与Kiruna型磷灰石-铁氧化物矿床相似。本文在野外工作基础上,通过流体包裹体测温和氢氧硫同位素研究,探讨该矿床成矿流体性质、来源及成矿作用。陶村主要矿石类型为浸染状和脉状磁铁矿,脉状矿石形成稍晚。通过包裹体显微测温获得:磷灰石中包裹体的均一温度集中在210~390℃,盐度集中在15%~23%NaCl_(eqv);石英中包裹体的均一温度集中在330~390℃,盐度主要集中在9%~13%NaCl_(eqv),此外还存在部分高盐度原生包裹体。石英的δD为-96‰~-54‰,δ~(18)O_(H2O)除了一个为8.3‰,其余为1.9‰~4.0‰,指示原始成矿流体为岩浆来源,后期有地表水加入。黄铁矿δ~(34)S为4.8‰~9.3‰,平均值为7.4‰,综合中段地区硫同位素资料,认为成矿流体中的硫来自三叠纪膏盐层与岩浆硫的混合。结合矿床地质特征,陶村成矿作用过程可概括为:岩浆出溶形成的高温含矿气液同化三叠纪膏盐层,带入SO_4~(2-)、Cl~-、Na~+等矿化剂;这种高温气液在岩体内以钠质交代形式富集Fe后,于岩体上部形成浸染状磁铁矿,岩体顶部和边部断裂部位形成(网)脉状磁铁矿。  相似文献   

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