金山金矿热液蚀变粘土矿物特征及水-岩反应环境研究

粘土矿物是流体作用过程中水—岩反应的产物，因此其特征反映了流体活动的特征和水-岩反应的环境。金山金矿蚀变粘土矿物主要由伊利石和绿泥石组成，其中，蚀变糜棱岩中的伊利石含量大于绿泥石含量；而蚀变超糜棱岩中的绿泥石含量大于伊利石含量。蚀变糜棱岩中伊利石的多型为2M1，超糜棱岩中为2M1和1M。金山金矿蚀变绿泥石的成份分析结果表明其为富铁绿泥石，由蠕绿泥石、铁镁绿泥石和密绿泥石组成，绿泥石中Fe、Mg质组分不仅来自围岩，而且也有一部分来自流体。利用地质温度计计算绿泥石的形成温度为206-258℃，流体的f(O2)为10^29.56～10^-31.48。本文认为金山金矿热液蚀变为酸性蚀变，其环境为还原环境，流体作用的水／岩比较高；在水—岩反应过程中，流体中的Fe、Mg、Si为带出组分。粘土矿物的形成机制为溶解—迁移—沉淀。     

江西银山多金属矿床伊利石的形成与流体成矿作用的初步研究

江西银山多金属矿床的热液蚀变粘土矿物主要由伊利石组成,伊利石主要由流体作用过程中长石的伊利石化形成,其结晶度与成矿流体作用密切相关.银山第1期铅锌银成矿作用,水/岩比相对较低,成矿流体以孔隙渗透为主,溶质迁移慢,形成含有少量膨胀层的伊利石;第2期铜金成矿作用,水/岩比相对较高,流体的运移方式以通道式或裂隙式为主,溶质迁移的速度快,形成不含膨胀层的伊利石.研究表明成矿作用过程中的伊利石化主要与铅锌银矿化有关,而绿泥石化与铜金矿化有关.     

成矿流体对德兴斑岩铜矿床中伊利石结晶度的控制作用

伊利石广泛存在于铜厂大型斑岩铜矿床内,是特征的热液蚀变矿物,其结晶度和膨胀层含量受携带矿质的热液流体量控制。以浸染状强矿化为特征的斑岩体中上部及接触带附近伊利石结晶程度较好,主要是高水／岩比作用的结果。同时指示出伊利石结晶程度好的部位,矿化品位高,蚀变程度也强。     

糜棱岩化过程中绿泥石多型与结晶度的演变--以郯庐断裂带南段为例

摘要：根据郯庐断裂带南段韧性剪切带糜棱岩中同构造矿物组合、黑云母的存在以及长石的变形行为，推测其变形．变质温度为400一450oC。bo值分析表明．这些糜棱岩是在低压环境下形成的。在流体作用下。糜棱岩中的绿泥石既可以交代其它矿物而形成，也可以直接从流体中结晶形成。交代其它矿物所形成的绿泥石为Ⅱ型绿泥石，其结晶度值介于0．21^。一0．23^。20．与温度具有较好的对应关系。直接从流体中结晶而产生的绿泥石初始时刻为工型．其结晶度值介于0．236^。-0．341^。20之间，多屑于近变带范畴。其指示温度要低于实际所经历的环境温度。由于糜棱岩化过程中工型绿泥石的不断产生以及工型绿泥石向Ⅱ型绿泥石转化的不充分。导致了在400以上仍然出现工型绿泥石与Ⅱ型绿泥石混合的现象．并且实测的结晶度是不同时刻形成的、具不同结晶度的绿泥石的混合结晶度。     

新疆布尔根韧脆性剪切带金矿地质特征

布尔根金矿带产于上泥盆统卡希翁组中基性火山岩中．金矿带严格地受韧性剪切带控制，赋矿岩石是韧脆性变形的破碎蚀变岩，主要是糜棱岩和石英细脉和网脉，围岩蚀变有硅化、黄铁绢英岩化、黄铁矿化、绿泥石化和高岭土化等．该金矿具韧性剪切破碎蚀变型金矿的特征．     

剪切带中矿化与非矿化地段流体——岩石相互作用差异性研究

以河南西峡石板沟金矿为例,选择了一条控矿剪切带,对其中成矿地段的近矿蚀变岩和非成矿地段糜棱岩进行了系统的采样,探讨了二者在流体-岩石反应及岩石质量平衡之间的差异性。研究表明,剪切带中矿化地段蚀变岩其岩石体积总是扩容的,非矿化地段糜棱岩在变形过程中体积是损失的。矿化地段蚀变岩活性元素(K、Na、Si)总体呈被带入趋势,非矿化地段糜棱岩活性元素总体呈迁出趋势,糜棱岩的流体岩石率(N_u为93.68—468.40)远大于蚀变岩的流体岩石率(Nc_(Ⅳ)^s为36.11-216.67),剪切带中常量元素与微量元素富集与损失是渗透性流体带入、带出,岩石的体积损失与扩容综合作用的结果。     

新疆冰达坂含金剪切带内组分分异及对金矿化的影响

新疆冰达坂含金剪切带内高品位金矿体更倾向定位于低应变带.选取典型剖面,对比蚀变围岩、矿石、未蚀变花岗质初糜棱岩及花岗质原岩组分特征,结果表明花岗质岩石容矿的金矿床剪切变形过程中组分发生分异,动力分异与流体分异对金矿化所起作用及相对程度不同,研究区金成矿主要与流体分异作用有关.流体分异作用过程中,相对于高应变带,低应变带内强分异形成的高Fe环境及扩容空间为金矿化、沉淀提供更有利条件,且碱(Na)交代排出的Si为浅层次硅化蚀变糜棱岩型及石英脉型矿化提供物源基础,K、 Ca、 Mg形成绢云母化、碳酸盐化、绿泥石化等蚀变,从而为区内金矿化定位及共生蚀变提供了合理解释.结合已有研究成果,认为钠长石化带下部应发育钾长石化带,且作为矿根相存在,矿带东、西段深部均有较好金矿化前景     

巴州坳陷下白垩统—中侏罗统的粘土矿物特征

根据岩石薄片、Ｘ衍射和扫描电镜分析资料,本文研究了巴州坳陷下白垩统—中侏罗统粘土矿物特征,发现粘土矿物分为伊利石、伊／蒙混层和绿泥石三种类型。粘土矿物的类型和含量随深度而变化,形成了伊／蒙混层带、混层迅速转化带和伊利石带。粘土矿物的转化和自生粘土矿物的形成是沉积地层非常重要的成岩变化。     

伊犁京希—伊尔曼德金矿床的热液蚀变及成矿流体演化特征

京希－伊尔曼德金矿床的热液蚀变在空间上有明显的分带性，中心蚀变带以强烈的硅化为主，典型的蚀变矿物组合为石英或玉髓和地开石，中间带为高级泥化带，以地开石－高岭石－石英或玉髓为特征；外带为以蒙脱石－高岭石－伊利石－其他粘土矿物等矿物组合为主的泥化带，蚀变强度和矿物组合的分带性是温度、压力和化学梯度的反映，是流体在不断的水或流体－岩石反应和成分交换的产物。该矿床成矿流体演化过程为：早期酸性（pH=2-3)含矿流体在沿断裂上升过程中，受围岩灰岩中的流体（pH为中性）缓冲，在其进入高渗透性的碎屑岩层时，流速和水－岩石或流休－岩石反应大大加快，并在与大气降水的混合作用下，pH值逐步升高（3－5），产生了流体的温度及成分梯度，在温度和压力迅速下降的条件下，金及蚀变矿物沉淀、结晶生长，形成了蚀变空间分带，中心带保存完好的多孔状石英和地开石等高级泥化矿物组合说明该矿床是高硫化热液体系作用下的产物。     

陕川丁家林-太阳坪-董家院金矿带的矿田构造-岩相学研究

陕西丁家林-四川太阳坪-四川董家院北东向金矿带位于后龙门山陆内造山带,构造动力学背景为陆-陆板块碰撞而形成的逆冲推覆造山带,金矿带内发育一系列与陆内造山作用密切有关的北东向递进脆-韧性剪切带。本文以构造-岩相学新方法为指导,在矿田构造-岩相学层次上,通过实测构造-岩相学剖面和岩石地球化学研究,对该金矿带物质学和运动学特征研究表明,赋矿地层志留系黄坪组(S1-2hn)区域性岩相学特征整体为陆棚相。黄坪组中部层间流体活动强烈,地壳浅部富Fe-Mg-CO32–型构造流体活动形成了斑点状铁碳酸盐千枚岩相;随构造变形层次加深,强应变带发育构造片岩相和初糜棱岩相,富Si O2型流体排泄的构造分异成岩作用形成了流变状糜棱岩相。强烈的构造成岩作用及造山带流体的大规模排泄形成了糜棱岩相,同位发育密集的流变状糜棱岩相和蚀变菱铁矿铁白云石网脉相。构造流体成岩成矿作用集中于强应变带形成蚀变糜棱岩相,后期脆性蚀变碎裂岩相叠加时,金矿化(体)发育。早期韧性剪切和脆韧性剪切变形并叠加有后期脆性变形构造,富集Au-Cu-Sb-W-Bi等元素组合。本区缺少或未见早三叠世以后形成的岩浆活动。大规模富Fe-Mg碳酸盐型流体及同构造期造山带流体活动与龙门山陆内造山带密切相关,表明丁家林-太阳坪-董家院金矿为造山型金矿。     

A Study of Illite Kiibler Indexes and Chlorite "Crystallinities" with Respect to Shear Deformation and Alterations, Jinshan Gold Deposit, East China

Abstract. This paper presents a measurement and study of Kübler Indexes (KI) of illite, "crystallinities" of chlorite (ChC), and apparent mean crystallite sizes and lattice strain of both illite and chlorite of the Jinshan ductile shear zone in the Jinshan gold deposit of East China. It is found that the KI values and apparent mean crystallite sizes of illite decrease and the lattice strain of chlorite apparently increase, whereas the apparent mean crystallite sizes of chlorite and the lattice strain of illite remain constant, from altered mylonite to altered and higher-strained ultramylonite in the shear zone. Only slight decrease of ChC is observed.
An obvious negative correlation exists between KI and apparent mean crystallite sizes in altered mylonite with lower strain, whereas a positive correlation is found between ChC and apparent mean crystallite sizes in altered ultramylonite with higher strain. No any correlations between KI and lattice strain exist, whereas a negative correlation and a positive correlation between ChC and lattice strain occur separately in the altered mylonite and ultramylonite. It is suggested that illite Kiibler Indexes and chlorite "crystallinities" most likely reflect deformation behaviors and mechanisms of altered rocks although other factors involving water/rock ratio may apply as well.     

德兴斑岩铜矿田两类伊利石的存在及其在蚀变分带中的意义

德兴斑岩铜矿田内存在两种成因类型的伊利石：一是特征的热液蚀变矿物,它是在热液流体 作用过程中斜长石、云母类矿物通过伊利石化过程形成的,其结晶度(IC)和膨胀层含量受携 带矿质的热液流体量控制;二是浅变质作用自身的产物,其结晶度远较小于前者,具2M1 多型,且不含膨胀层,是原始蒙皂石完全伊利石化形成的。作者发现,在斑岩体和接触带内 ,伊利石结晶度小的部位,蚀变程度强,矿化品位也高。     

Postsedimentation transformation of triassic terrigenous rocks in West Chukotka as an indicator of folding conditions

Postsedimentation alteration and structural assemblies of the Triassic sedimentary complexes of West Chukotka are discussed. Zoning of the alteration is based on examination of newly formed structural and mineral assemblages, the chemical composition, and the polytypes of clay minerals. Three zones of postsedimentation transformation of sandstones are distinguished: (1) the zone of chlorite, illite, and mixed-layer disordered chlorite-smectite; (2) the zone of illite and chlorite; and (3) the zone of phengite and ferroan chlorite. The grade of postsedimentation transformation and the composition of the newly formed micas are correlated with the cleavage type. The development of two-three types of cleavage leads to the highest degree of rock transformation. The assemblages of clay minerals and the crystal chemistry of the authigenic phengite show that the grade of postsedimentation transformation of the Triassic rocks attains the stage of greenschistfacies metamorphism in the zone of development of two cleavage types. Where the second cleavage is not documented or poorly developed, the rocks remain unmetamorphosed. Evidence is given that postsedimentation transformation of terrigenous rocks in the foldbelt is controlled largely by deformation.     

Origin of Illites at Dexing Porphyry Copper Deposit,Jiangxi Province,East China：Implications for Alteration Zoning and Ore—Forming Fluid Evolution

According to differences in features of illites including spatial distribution, crystallinity index, volume of swelling layer, polytype and relationship between its index and copper grade, two typical kinds of illite can be classified within the Tongchang porphyry copper deposit, Dexing County, East China. One is a kind of hydrothermally altered minerals within the hydrothermal alteration zone, including altered granodiorite-porphyry and altered metamorphic tuffaceous phyllite near the contact zone with porphyry rockbody. The illite crystallinity and expandability are mainly affected by water/rock ratio or fluid flux, and hydrothermal illite is formed by illitization of plagioclase and/or micas during hydrothermal fluid evolution within the porphyry body and near the contact zone with wall rocks. The other is a product of low-grade metamorphism itself by illitization of smectite, whose crystallinity index is lower than the hydrothermal illite and which is of 2M₁ polytype with no swelling layer, in the altered metamorphic tuffaceous phyllite far from porphyry rockbody ( > 2 km). Moreover, the negative correlation between illite index and copper grade indicates that, within the alteration zone, the smaller the illite crystallinity, the stronger the alteration degree, and the higher the copper grade due to higher water/rock ratio. At lower levels of the porphyry body, however, the illite crystallinity (IC) values are controlled mainly by temperature and time.     

Comparison of diagenetic and low-grade metamorphic evolution of chlorite in associated metapelites and metabasites: an integrated TEM and XRD study

Chlorite is a common sheet silicate that occurs in various lithologies over a wide grade range involving diagenesis and low‐grade metamorphism. Thus, the reaction progress of chlorite offers a unique opportunity for direct correlation of zonal classification of metasedimentary rocks based on illite crystallinity with metabasite mineral facies. To provide such correlation, chlorite crystallinity indices, apparent mean crystallite sizes and lattice strains, crystallite size distributions and compositions of chlorite from coexisting metapelites and metabasites were determined by X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), analytical electron microscopy (AEM) and electron microprobe (EMP) methods. Samples were from Palaeozoic and Mesozoic formations of the Bükkium (innermost Western Carpathians, Hungary) that underwent Alpine (Cretaceous) orogenic metamorphism. Metapelites range in grade from late diagenesis to epizone, whereas metabasites vary from prehnite–pumpellyite through pumpellyite–actinolite to greenschist facies. Despite significant differences in composition, mineral assemblages and textures, reaction progress, as measured in part by chlorite crystallinity, in metapelites paralleled that in metabasites. Chlorite crystallinity and mean crystallite size increase and the proportion of mixed layers in chlorite decreases, whereas the calculated lattice strain does not change significantly with increasing metamorphic grade. Similar trends, but (especially at higher grades) significant differences, were found in mean crystallite size values using various methods for XRD line profile analyses. The increase in crystallite size with increasing grade was demonstrated also by direct TEM measurements on ion‐milled whole‐rock samples, but with a larger scatter of data at higher grades. In spite of the different kinds of mixed layering in chlorite (Mg‐rich smectitic, mostly random, local corrensite‐like units in metabasites, and Fe‐rich berthierine and dioctahedral smectite in metapelites), XRD‐calculated and TEM‐measured parameters were found to be reliable tools for measuring reaction progress and metamorphic grade of the same degree in both lithotypes.     

成岩带、近变质带与一维纳米级层状硅酸盐

运用X射线衍射分析技术，计算了成岩带、近变质带粘土矿物C^*方向的粒度。根据阿尔卑斯造山带前陆碎屑岩粘土矿物粒度与伊利石结晶指数的关系，推导出了伊利石、绿泥石、蒙脱石、伊蒙混层、高岭石和叶蜡石的c^*方向粒度变化趋势曲线。结果表明，大多数产于成岩带和近变质带的粘矿物其c6*方向粒工为几至几十纳米。成岩带和近为质带是一维天然纳为级土帮物的产地。     

Variations in Chemical Composition of Clay Minerals and Magnetic Susceptibility of Hydrothermally Altered Rocks in the Hishikari Epithermal Gold Deposit, SW Kyushu, Japan

Hydrothermal alteration, involving chiefly chlorite and illite, is extensively distributed within host rocks of the Pleistocene Hishikari Lower Andesites (HLA) and the Cretaceous Shimanto Supergroup (SSG) in the underground mining area of the Hishikari epithermal gold deposit, Kagoshima, Japan. Approximately 60% of the mineable auriferous quartz‐adularia veins in the Honko vein system occur in sedimentary rocks of the SSG, whereas all the veins of the Yamada vein system occur in volcanic rocks of the HLA. Variations in the abundance and chemical composition of hydrothermal minerals and magnetic susceptibility of the hydrothermally altered rocks of the HLA and SSG were analyzed. In volcanic rocks of the HLA, hydrothermal minerals such as quartz, chlorite, adularia, illite, and pyrite replaced primary minerals. The amount of hydrothermal minerals in the volcanic rocks including chlorite, adularia, illite, and pyrite as well as the altered and/or replaced pyroxenes and plagioclase phenocrysts increases toward the veins in the Honko vein system. The vein‐centered variation in mineral assemblage is pronounced within up to 25 m from the veins in the peripheral area of the Honko vein system, whereas it is not as apparent in the Yamada vein system. The hydrothermal minerals in sandstone of the SSG occur mainly as seams less than a few millimeters thick and are sporadically observed in halos along the veins and/or the seams. The alteration halos in sandstone of the SSG are restricted to within 1 m of the veins. In the peripheral area of the Honko vein system, chlorite in volcanic rocks is characterized by increasing in Al in its tetrahedral layer and the Fe/Fe + Mg ratio toward the veins, while illite in volcanic rocks has relatively low K and a restricted range of Fe/Fe + Mg ratios. Temperature estimates derived from chlorite geothermometry rise toward the veins within the volcanic rocks. The magnetic susceptibility of tuff breccia of the HLA varies from 21 to less than 0.01 × 10^?3 SI within a span of 40 m from the veins and has significant variation relative to that of andesite (27–0.06 × 10^?3 SI). The variation peripheral to the Honko vein system correlates with an increase in the abundance of hematite pseudomorphs after magnetite, the percentage of adularia and chlorite with high Fe/Fe + Mg ratios, and the degree of plagioclase alteration with decreasing distance to the veins. In contrast, sedimentary rocks of the SSG maintain a consistent magnetic susceptibility across the alteration zone, within a narrow range from 0.3 to 0.2 × 10^?3 SI. Magnetic susceptibility of volcanic rocks of the HLA, especially tuff breccia, could serve as an effective exploration tool for identifying altered volcanic rocks.     

Mineralogical, geochemical and isotopic characteristics of hydrothermal alteration processes in the active, submarine, felsic-hosted PACMANUS field, Manus Basin, Papua New Guinea

During ODP Leg 193, 4 sites were drilled in the active PACMANUS hydrothermal field on the crest of the felsic Pual Ridge to examine the vertical and lateral variations in mineralization and alteration patterns. We present new data on clay mineral assemblages, clay and whole rock chemistry and clay mineral strontium and oxygen isotopic compositions of altered rocks from a site of diffuse low-temperature venting (Snowcap, Site 1188) and a site of high-temperature venting (Roman Ruins, Site 1189) in order to investigate the water-rock reactions and associated elemental exchanges.The volcanic succession at Snowcap has been hydrothermally altered, producing five alteration zones: (1) chlorite ± illite-cristobalite-plagioclase alteration apparently overprinted locally by pyrophyllite bleaching at temperatures of 260-310°C; (2) chlorite ± mixed-layer clay alteration at temperatures of 230°C; (3) chlorite and illite alteration; (4) illite and chlorite ± illite mixed-layer alteration at temperatures of 250-260°C; and (5) illite ± chlorite alteration at 290-300°C. Felsic rocks recovered from two holes (1189A and 1189B) at Roman Ruins, although very close together, show differing alteration features. Hole 1189A is characterized by a uniform chlorite-illite alteration formed at ∼250°C, overprinted by quartz veining at 350°C. In contrast, four alteration zones occur in Hole 1189B: (1) illite ± chlorite alteration formed at ∼300°C; (2) chlorite ± illite alteration at 235°C; (3) chlorite ± illite and mixed layer clay alteration; and (4) chlorite ± illite alteration at 220°C.Mass balance calculations indicate that the chloritization, illitization and bleaching (silica-pyrophyllite assemblages) alteration stages are accompanied by different chemical changes relative to a calculated pristine precursor lava. The element Cr appears to have a general enrichment in the altered samples from PACMANUS. The clay concentrate data show that Cr and Cu are predominantly present in the pyrophyllites. Illite shows a significant enrichment for Cs and Cu relative to the bulk altered samples.Considerations of mineral stability allow us to place some constraints on fluid chemistry. Hydrothermal fluid pH for the chloritization and illitization was neutral to slightly acidic and relatively acidic for the pyrophyllite alteration. In general the fluids, especially from Roman Ruins and at intermediate depths below Snowcap, show only a small proportion of seawater mixing (<10%). Fluids in shallow and deep parts of the Snowcap holes, in contrast, show stronger seawater influence.     

韧性剪切带内的流体与岩石相互作用研究进展

构造变形与流体联合控制成矿作用的机制是矿床学界关注的热点问题之一。作为大陆岩石圈中的应变局部化带,剪切带中一般都渗透着大量流体,流体与岩石的相互作用及其化学效应和物理效应,导致了矿物化学不平衡和组分的迁移,引起岩石化学成分重新调整。文章通过对韧性剪切带内的流体作用、剪切带内的成分与体积变化、剪切变形与成矿模拟实验总结,讨论了剪切变形过程中的力学-化学作用、剪切构造应力和流体在构造成岩成矿过程中的行为。因此,要加强构造应力对温度、岩石物理性质、地球化学相平衡和水岩体系的相关参量方面影响的综合研究。      

可可西里盐湖表层沉积物中粘土矿物的环境信息

通过对可可西里盐湖表层沉积物中粘土矿物的研究,以期获得近年来湖区的某些环境信息.研究结果表明:沉积物中的粘土矿物主要为伊利石和绿泥石,非粘土矿物主要为石英、方解石和长石以及少量白云石、文石、闪石和石膏等.样品中＜2μm的粘土矿物以伊利石和绿泥石为主,局部样品含少量有序伊/蒙混层.根据样品分布特点和粘土矿物的组合类型,将样品划分为3个区域:1区和3区的矿物组合为伊利石、绿泥石和有序伊/蒙混层;2区为伊利石和绿泥石,无伊像混层矿物.其中1区和3区样品的结晶度(IC)范围为0.41～0.59,均值为0.51;2区样品的结晶度范围为0.25～0.40,均值为0.34,明显低于1区和3区,说明2区样品中的伊利石具有更高的结晶度.样品的伊利石化学指数(CI)均小于0.5,表明该伊利石为富Fe-Mg伊利石,主要是物理风化作用的结果.伊利石和绿泥石作为主要粘土矿物反映了近年来整个湖区的环境以干冷为主,局部区域(1区和3区)出现的少量有序I/S混层矿物则指示在短期内曾经历过短暂的干湿交替环境.此外,在酸性介质条件下,少量伊利石发生弱水解作用导致晶格中的K+淋失,并转化为伊/蒙混层矿物,同时也降低了伊利石的结晶度.