造山型金矿中富CO_(2)高内压流体包裹体完全均一温度的有效测定实验研究——以东天山玉峰金矿床为例SCIEI北大核心CSCD     

于立栋  李胜虎  张静  何西恒  于学峰  单伟  迟乃杰 《岩石学报》2022,38(1):267-280

形成于中-深成条件下的造山型金矿的成矿流体属于H_(2)O-NaCl-CO_(2)体系,金矿化阶段的石英中发育大量的富CO_(2)流体包裹体。长期以来,用常规冷热台对其进行显微测温热力学研究时,较高的内压力会造成绝大多数CO_(2)充填度>0.4的包裹体在尚未达到完全均一状态前就发生爆裂或泄露,导致所测的完全均一温度值明显偏离真实值,甚至无法测得完全均一温度,这制约了对造山型金矿床成矿条件的认知。针对该问题,本文以东天山玉峰金矿床富金矿石中的H_(2)O-NaCl包裹体(A型)和H_(2)O-NaCl-CO_(2)包裹体(AC型)为研究对象,介绍了利用最新型热液金刚石压腔(HDAC-VT型号)测试富CO_(2)高内压的AC型包裹体完全均一温度的实验流程与结果,并将实验数据与Linkam THMSG600冷热台测得的A型、AC型包裹体的完全均一温度进行了对比分析。实验结果表明,热液金刚石压腔能够有效阻止富CO_(2)流体包裹体在升温过程中发生爆裂、泄露等非弹性体积改变现象的发生,从而获得有效的完全均一温度。同时,本文还提出了一个新的压力-温度拟合线两线相交法,对热液金刚石压腔所测富CO_(2)流体包裹体的完全均一温度数据进行校正,以最大程度上减少外压力造成的影响,获得更为接近真实成矿流体的完全均一温度。基于此,获得玉峰金矿床的成矿温度和成矿压力分别为312~343℃和181~268 MPa。本文的实验研究工作显示了热液金刚石压腔在中-深成造山型金矿富CO_(2)成矿流体的研究领域具有重要应用前景。  相似文献   

滇西兰坪盆地茅草坪脉状Cu矿床流体包裹体和稳定同位素地球化学研究   总被引：2，自引：2，他引：0  

程杨  宋玉财  侯增谦  薛传东  黄世强  韩朝辉  庄亮亮 《岩石学报》2015,31(11):3363-3379

兰坪盆地西缘发育一条重要的脉状Cu矿带,矿床的成矿流体来源一直存在较大的争议。本次研究对该矿带南段新发现的茅草坪矿床进行流体包裹体和H-O-C-S同位素研究,结合前人发表的该矿带矿床的同位素数据,探讨矿床成矿流体特征和来源。茅草坪矿床早(A1脉)、晚(A2脉)两期含矿石英脉中的流体包裹体均为含CO2盐水包裹体,可细分为含石盐子晶、富液相(水溶液相)、富气相(CO2相)包裹体等不同类型。根据流体包裹体的共生特点,将其划分为3组包裹体组合:(1)第I组,出现在A1脉石英中,为富液相(I-W型)、富气相(I-C型)和含石盐子晶(I-S型)包裹体共生;(2)第Ⅱ组,同样出现在A1脉石英中,为富液相(Ⅱ-W型)和富气相(Ⅱ-C型)包裹体共生;(3)第Ⅲ组,出现在A2脉石英中,为富液相(Ⅲ-W型)和富气相(Ⅲ-C型)包裹体共生。测温结果显示:I-S型包裹体均一温度在293~370℃之间,流体盐度为30.06%~39.76%Na Cleqv;Ⅱ-W型包裹体均一温度在302~490℃之间,流体盐度为1.23%~18.63%Na Cleqv;Ⅲ-W型包裹体均一温度在263~400℃之间,流体盐度为1.20%~11.34%Na Cleqv。同一组内,包裹体气/液相比高度变化,表明包裹体捕获时的流体呈不均一态,此时包裹体均一温度中低值部分近似代表该组包裹体真实的捕获温度。因此,从I组到Ⅲ组,包裹体分别捕获于280~320℃(I组、Ⅱ组)和260~280℃(Ⅲ组),结合盐度数据,反应初始成矿流体发生沸腾作用,伴随石盐子晶析出,流体盐度下降,随后温度降低。茅草坪矿床成矿流体富CO2的特点与区域内其他脉状Cu矿床一致,但盐度明显偏高。矿床热液石英的δDV-SMOW值变化在-94.6‰~-56.2‰之间,计算的流体的δ18OV-SMOW值集中在+8.1‰~+9.6‰之间,与区域其他脉状Cu矿床相似,数据主要落在原生岩浆水区域的下方,表明流体来源于岩浆水,但经历了开放系统下的脱气作用,没有盆地流体或大气降水的贡献;热液碳酸盐方解石的δ13CV-PDF值为-8.3‰~-2.4‰,δ18OV-SMOW值为14.46‰~16.63‰,与区域其他脉状Cu矿床的C-O同位素组成相似,但C同位素组成明显低于区域脉状Pb-Zn矿床(碳主要来自盆地流体溶解的碳酸盐岩);黄铜矿的δ34SV-CDT值变化于-6.4‰~-3.9‰之间,处于区域其他脉状Cu矿床的S同位素组成范围内,但区别于区域砂岩型Cu矿床(硫来自硫酸盐的细菌还原作用)。因此,推测矿床的CO2和硫可能也来自脱气的岩浆。茅草坪脉状Cu矿床成矿流体的研究表明:兰坪盆地西缘脉状Cu矿床成矿流体可能来自富CO2、经历脱气的岩浆水,没有大气降水和盆地卤水的参与。  相似文献   

西秦岭阳山金矿带安坝矿床热液蚀变作用   总被引：6，自引：4，他引：2  

张志超  李楠  戢兴忠  韩忠  郭耀宇  李在春 《岩石学报》2015,31(11):3405-3419

安坝金矿床是阳山金矿带内已探明金资源储量最大的金矿床,矿体受NEE向的区域性安昌河-观音坝断裂带及其次级断裂-裂隙系统控制,主要赋存于紧邻断裂带的千枚岩和斜长花岗斑岩中。围绕断裂-裂隙系统的赋矿围岩硫化、硅化、绢云母化、碳酸盐化、绿泥石化、绿帘石化和粘土化蚀变发育,其中前三种蚀变与金成矿作用关系最为密切。论文在厘定安坝金矿床热液蚀变类型、矿物组合特征、以及断裂变形与蚀变空间变化关系的基础上,通过对蚀变岩及其原岩的地球化学分析,剖析了热液蚀变作用过程与机理。研究结果表明,硅化蚀变贯穿发育于成矿前、成矿期和成矿后,绢云母化蚀变为成矿前和成矿期的产物,碳酸盐化蚀变主要发育于成矿晚阶段和成矿后,而粘土化蚀变为成矿后的产物。在长石蚀变为绢云母的过程中,有少量Al2O3带出,而TiO 2在蚀变过程中相对稳定,为此选取TiO 2作为不活动组分,开展质量平衡计算得出:在硅化过程中,明显带入的组分有SiO 2、Fe2O3、FeO、MgO、CaO、C、S、Au、As、Hg、Pb和Zn,而被带出的元素为Rb和Ba;在绢云母化过程中,明显带入的组分为SiO 2、Fe2O3、CaO、C、S、Au、As、Hg、Pb、Zn、Rb和Ba,带出组分为Na2O。稀土元素地球化学特征显示千枚岩原岩稀土元素含量比硅化和绢云母化千枚岩的稀土元素含量高,表明在蚀变过程中有稀土元素的流失。此外,千枚岩原岩的δEu=0.70,δCe=0.95;硅化千枚岩的δEu=0.72,δCe=1.00;绢云母化千枚岩的δEu=0.76,δCe=0.95。硅化、绢云母化千枚岩与千枚岩原岩的REE球粒陨石标准化配分模式曲线变化趋势相似,表现为明显的Eu负异常、无Ce异常的富轻稀土的右倾型曲线。含矿流体沿断裂带运移并与围岩反应,形成了石英和绢云母等蚀变矿物。硅化过程中,含矿流体中还原硫活度降低导致金沉淀;而绢云母化过程中,含矿流体的pH增大及K+和H+含量的减少和CO2含量的增加,致使载金黄铁矿、毒砂和金的沉淀。  相似文献   

Characterization of Galena and Vein Paragenesis in the Penjom Gold Mine, Malaysia: Trace Elements, Lead Isotope Study and Relationship to Gold Mineralization Episodes     

Zakaria ENDUT  NG Tham Fatt  Jasmi Hafiz ABDUL AZIZ  Sebastien MEFFRE  Charles MAKOUNDI 《《地质学报》英文版》2015,89(6):1914-1925

The Penjom Gold Mine is located 30 km from the Bentong-Raub Suture at the western boundary of the Central Belt in Peninsular Malaysia. Gold mineralization hosted within the vein system is associated with pyrite, arsenopyrite, and minor base metals including galena. Trace element and lead isotope analysis was undertaken on nine samples that represent two stages of galena formed during two tectonic events. Both the Pb isotopes and the trace elements show that the first stage galena within the mineralized areas at the footwall has different geochemical characteristics compared with galena in non mineralized areas in the hanging wall, suggesting that galena crystallized from two different ore fluids and probably at two different times. Higher Te, Se and Bi in the galena from the mineralized area may indicate hydrothermal fluids that migrate through the structural conduit and leached out the metal along the pathway that consist of dominant carbonaceous unit. The Pb isotopic ratio composition are transitional between the bulk crustal growth and an upper crustal growth curve, indicating that derivation was from arc rocks associated with continental crust or a crustal source that includes arc volcanic and old continental sedimentary rocks.  相似文献   

A range of fault slip styles on progressively misoriented planes during flexural-slip folding,Cape Fold Belt,South Africa     

《Journal of Structural Geology》2015

Flexural slip folds are distinctive of mixed continuous-discontinuous deformation in the upper crust, as folding is accommodated by continuous bending of layers and localized, discontinuous slip along layer interfaces. The mechanism of localized, layer-parallel slip and the stress and fluid pressure conditions at which flexural slip occurs are therefore distinctive of shear localization during distributed deformation. In the Prince Albert Formation mudstone sequence of the Karoo Basin, the foreland basin to the Cape Fold Belt, folds are well developed and associated with incrementally developed bedding-parallel quartz veins with slickenfibers oriented perpendicular to fold hinge lines, locally cross-cutting axial planar cleavage, and showing hanging wall motion toward the fold hinge. Bedding-parallel slickenfiber-coated veins dip at angles from 18° to 83°, implying that late increments of bedding-parallel shear occurred along unfavorably oriented planes. The local presence of tensile veins, in mutually cross-cutting relationship with bedding-parallel, slickenfiber-coated veins, indicate local fluid pressures in excess of the least compressive stress.Slickenfiber vein microstructures include a range of quartz morphologies, dominantly blocky to elongate-blocky, but in places euhedral to subhedral; the veins are commonly laminated, with layers of quartz separated by bedding-parallel slip surfaces characterized by a quartz-phyllosilicate cataclasite. Crack-seal bands imply incremental slickenfiber growth, in increments from tens of micrometers to a few millimeters, in some places, whereas other vein layers lack evidence for incremental growth and likely formed in single slip events. Single slip events, however, also involved quartz growth into open space, and are inferred to have formed by stick-slip faulting. Overall, therefore, flexural slip in this location involved bedding-parallel faulting, along progressively misoriented weak planes, with a range of slip increments.  相似文献   

南秦岭主要类型热水沉积岩的REE地球化学   总被引：1，自引：0，他引：1  

薛春纪  马国良  隗合明  曾章仁 《地球科学与环境学报》1996,(3)

南秦岭泥盆纪沉积柱中产有多种类型海底热水沉积岩．它们的ΣＲＥＥ偏低（平均６３．０９×１０－６），ＲＥＥ配分曲线平缓右倾，Ｌａ／Ｙｂ＝２～８，Ｃｅ亏损，总体上与海水相似。产于Ｓｅｄｅｘ含矿层中的热水沉积岩具有正Ｅｕ异常，与现代海底热液及红海热液沉积物可比；而产在Ｓｅｄｅｘ含矿层以下地层中的热水沉积岩Ｅｕ亏损，与ＥＰＲ热液沉积物相似。ＲＥＥ地球化学研究和岩石学研究结果一致，支持热水沉积岩ＲＥＥ来源于海水及部分下伏沉积柱（包括基底），含矿热水沉积岩是盆地热演化到一定阶段具有一定深度和规模的循环对流体系在海底的化学沉积，而Ｓｅｄｅｘ含矿层以下地层中的热水沉积岩则是浅部热水对流循环的海底显示．成岩和变质作用对岩石的ＲＥＥ未造成影响。  相似文献   

乔治王岛菲尔德斯半岛的地温特征和岩石热物理性质          下载免费PDF全文

杨淑贞  张文仁  沈显杰 《极地研究》1989,1(3):43-51

1985—1986年度和1986—1987年度在菲尔德斯半岛对地面温度进行了测量,共获得129个数据,并对带回的样品进行了岩石热导率测量,共获得210个数据。本文在分析和归纳这些数据的基础上对菲尔德斯半岛的地温特征和岩石热物理性质进行了初步探讨。  相似文献   

东川拖布卡金矿矿化层位与找金方向   总被引：10，自引：3，他引：7  

薛步高 《云南地质》2005,24(3):243-253

超大型拖布卡金矿的发现,表明东川地区具备找金前景.“黑层”是金的成矿前提,断裂加蚀变是成矿必备条件,基性与中性岩脉在容矿层中的侵位,是找富金的重要标志.金成矿全过程应是多旋回（晋宁、华力西、燕山、喜马拉雅山）成矿作用,且受剪切破碎带控制的黑层型金矿.  相似文献   

Diffuse CO<Subscript>2</Subscript> degassing at Vesuvio,Italy   总被引：1，自引：0，他引：1  

Francesco?FrondiniEmail author  Giovanni?Chiodini  Stefano?Caliro  Carlo?Cardellini  Domenico?Granieri  Guido?Ventura 《Bulletin of Volcanology》2004,66(7):642-651

At Vesuvio, a significant fraction of the rising hydrothermal–volcanic fluids is subjected to a condensation and separation process producing a CO₂–rich gas phase, mainly expulsed through soil diffuse degassing from well defined areas called diffuse degassing structures (DDS), and a liquid phase that flows towards the outer part of the volcanic cone. A large amount of thermal energy is associated with the steam condensation process and subsequent cooling of the liquid phase. The total amount of volcanic–hydrothermal CO₂ discharged through diffuse degassing has been computed through a sequential Gaussian simulation (sGs) approach based on several hundred accumulation chamber measurements and, at the time of the survey, amounted to 151 t d^–1. The steam associated with the CO₂ output, computed assuming that the original H₂O/CO₂ ratio of hydrothermal fluids is preserved in fumarolic effluents, is 553 t d^–1, and the energy produced by the steam condensation and cooling of the liquid phase is 1.47×10¹² J d^–1 (17 MW). The location of the CO₂ and temperature anomalies show that most of the gas is discharged from the inner part of the crater and suggests that crater morphology and local stratigraphy exert strong control on CO₂ degassing and subsurface steam condensation. The amounts of gas and energy released by Vesuvio are comparable to those released by other volcanic degassing areas of the world and their estimates, through periodic surveys of soil CO₂ flux, can constitute a useful tool to monitor volcanic activity.Editorial responsibility: H. Shinohara  相似文献   

Using the geologic setting of talc deposits as an indicator of amphibole asbestos content   总被引：1，自引：0，他引：1  

Bradley?S.?Van GosenEmail author  Heather?A.?Lowers  Stephen?J.?Sutley  Carol?A.?Gent 《Environmental Geology》2004,45(7):920-939

This study examined commercial talc deposits in the U.S. and their amphibole-asbestos content. The study found that the talc-forming environment directly influenced the amphibole and amphibole-asbestos content of the talc deposit. Large talc districts in the U.S. have mined hydrothermal talcs that replaced dolostone. Hydrothermal talcs, created by siliceous fluids heated by magmas at depth, consistently lack amphiboles as accessory minerals. In contrast, mineable talc deposits that formed by contact or regional metamorphism consistently contain amphiboles, locally as asbestiform varieties. Examples of contact metamorphic deposits occur in Death Valley, California; these talc-tremolite deposits contain accessory amphibole-asbestos. Talc bodies formed by regional metamorphism always contain amphiboles, which display a variety of compositions and habits, including asbestiform. Some industrial mineral deposits are under scrutiny as potential sources of accessory asbestos minerals. Recognizing consistent relations between the talc-forming environment and amphibole-asbestos content may be used in prioritizing remediation or monitoring of abandoned and active talc mines.  相似文献