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Overprinting porphyry‐type veinlets on the intrusive rocks and phreatomagmatic breccias in the Southwest prospect, southwestern Sto. Tomas II (Philex), Baguio District, Philippines 西南远景区侵入岩与渗透岩浆角砾岩上的套印斑岩型脉脉。托马斯二世(Philex),碧瑶区,菲律宾
IF 1.4 4区 地球科学 Q2 Earth and Planetary Sciences Pub Date : 2020-10-13 DOI: 10.1111/rge.12242
Avriel Venis Literal Cirineo, A. Imai, R. Takahashi, Redempta P. Baluda, N. Oliveros, V. B. Maglambayan, Roy Ronald C. Luis, Maria Lourdes M. Faustino, Jacky P. Almadin
The Southwest prospect is located at the southwestern periphery of the Sto. Tomas II porphyry copper–gold deposit in the Baguio District, northwestern Luzon, Philippines. The Southwest prospect hosts a copper‐gold mineralization related to a complex of porphyry intrusions, breccia facies, and overlapping porphyry‐type veinlets emplaced within the basement Pugo metavolcanics rocks and conglomerates of the Zigzag Formation. The occurrences of porphyry‐type veinlets and potassic alteration hosted in the complex are thought to be indications of the presence of blind porphyry deposits within the Sto. Tomas II vicinity. The complex is composed of at least four broadly mineralogically similar dioritic intrusive rocks that vary in texture and alteration type and intensity. These intrusions were accompanied with at least five breccia facies that were formed by the explosive brecciation, induced by the magmatic–hydrothermal processes and phreatomagmatic activities during the emplacement of the various intrusions. Hydrothermal alteration assemblages consisting of potassic, chlorite–magnetite, propylitic and sericite–chlorite alteration, and contemporaneous veinlet types were developed on the host rocks. Elevated copper and gold grades correspond to (a) chalcopyrite–bornite assemblage in the potassic alteration in the syn‐mineralization early‐mineralization diorite (EMD) and contemporaneous veinlets and (b) chalcopyrite‐rich mineralization associated with the chalcopyrite–magnetite–chlorite–actinolite±sericite veinlets contemporaneous with the chlorite–magnetite alteration. Erratic remarkable concentrations of gold were also present in the late‐mineralization Late Diorite (LD). High XMg of calcic amphiboles (>0.60) in the intrusive rocks indicate that the magmas have been oxidizing since the early stages of crystallization, while a gap in the composition of Al between the rim and the cores of the calcic amphiboles in the EMD and LD indicate decompression at some point during the crystallization of these intrusive rocks. Fluid inclusion microthermometry suggests the trapping of immiscible fluids that formed the potassic alteration, associated ore mineralization, and sheeted quartz veinlets. The corresponding formation conditions of the shallower and deeper quartz veinlets were estimated at pressures of 50 and 30 MPa and temperatures of 554 and 436°C at depths of 1.9 and 1.1 km. Temperature data from the chlorite indicate that the chalcopyrite‐rich mineralization associated with the chlorite–magnetite alteration was formed at a much lower temperature (ca. 290°C) than the potassic alteration. Evidence from the vein offsetting matrix suggests multiple intrusions within the EMD, despite the K‐Ar ages of the potassic alteration in EMD and hornblende in the LD of about the same age at 3.5 ± 0.3 Ma. The K‐Ar age of the potassic alteration was likely to be thermally reset as a result of the overprinting hydrothermal alteration. The constrained K‐Ar ages also indicate
西南远景区位于Sto的西南边缘。菲律宾吕宋岛西北部碧瑶地区的托马斯二斑岩型铜金矿床。西南远景区有一个与斑岩侵入体、角砾岩相和叠置斑岩型脉脉有关的铜金矿化,这些斑岩侵入体位于基岩Pugo变质火山岩和锯齿组砾岩中。斑岩型脉脉的出现和钾蚀变被认为是Sto内存在盲斑岩矿床的迹象。托马斯二世附近。该杂岩由至少4块矿物学上大致相似的闪长质侵入岩组成,它们的结构、蚀变类型和强度各不相同。这些侵入体还伴有至少5个角砾岩相,这些角砾岩相是由各种侵入体侵位过程中岩浆热液作用和呼吸岩浆活动诱发的爆炸角砾岩形成的。热液蚀变组合主要为钾质蚀变、绿泥石—磁铁矿蚀变、丙质蚀变和绢云母—绿泥石蚀变组合以及同生脉蚀变类型。铜和金品位的升高对应于(a)同矿化早期闪长岩(EMD)钾化蚀变中的黄铜矿-斑铜矿组合和同时期的细脉;(b)与同时期的绿泥石-磁铁矿-绿泥石-放线石±绢云母细脉相关的黄铜矿富矿化。在成矿晚期闪长岩(LD)中也存在不稳定的显著金浓度。侵入岩中钙质角闪石的高XMg值(>0.60)表明岩浆从结晶早期开始就处于氧化状态,而EMD和LD中钙质角闪石边缘与岩心之间存在Al组成的间隙,表明这些侵入岩在结晶过程中出现了某种程度的降压。流体包裹体显微测温表明,形成钾蚀变、伴生矿化和片状石英脉的不混溶流体被圈闭。在1.9 km和1.1 km的压力为50 MPa和30 MPa,温度为554℃和436℃的条件下,估计了较浅和较深石英脉的形成条件。绿泥石的温度数据表明,与绿泥石-磁铁矿蚀变相关的富含黄铜矿的矿化形成于比钾蚀变低得多的温度(约290℃)。尽管EMD中钾质改变的K - Ar年龄与LD中角闪石的K - Ar年龄大致相同,均为3.5±0.3 Ma,但来自静脉偏移基质的证据表明EMD中存在多个侵入。钾化蚀变的K - Ar年龄可能由于热液的叠印蚀变而被热重置。限定的K - Ar年龄也表明西南远景区形成较早的侵入岩,可能与Sto最早的“暗闪长岩”侵入岩同时期。托马斯二世存款。西南远景区硫化物矿物δ34S范围为+1.8‰~ +5.1‰,与其余斑岩型铜矿和浅成热液矿床有密切的重叠。托马斯二世矿床及其附近。这表明该矿床的硫化物可能是在该区的斑岩铜矿床和浅成热液矿床中形成的。托马斯二世矿体及其附近。研究结果表明,与碧瑶地区其他斑岩矿床相比,西南远景区斑岩型铜脉及其钾蚀变形成时间较早,层位较浅。
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引用次数: 4
Geochronology and S–Pb–O–H isotopic constraints on the generation of the Luoyang Fe deposit in southwest Fujian Province, SE China 闽西南洛阳铁矿成矿的年代学及S-Pb-O-H同位素约束
IF 1.4 4区 地球科学 Q2 Earth and Planetary Sciences Pub Date : 2020-10-06 DOI: 10.1111/rge.12247
Sen Wang, Da Zhang, Tengda Yu, Ganguo Wu, Y. Di, Yaoyao Zhang, Jimin Yao
The Luoyang Fe polymetallic deposit is a well‐known Makeng‐type ore deposit in a late Paleozoic basin in southwest Fujian, southeast China. To investigate the generation of Makeng‐type Fe deposits, we conducted an integrated study of geochronology and S–Pb–O–H isotope compositions of the Luoyang Fe deposit. The LA–ICP–MS zircon U–Pb ages of the granite and Re–Os ages of the molybdenite suggest that the emplacement of the granite was coeval with the mineralization of the Luoyang deposit at 133–131 Ma. The H–O and S–Pb isotope compositions indicate that the metallogenic material of the Luoyang deposit had a magmatic hydrothermal source, and was derived mainly from the upper crust with a low degree of contamination of mantle material. The Pb isotope analyses of the ore minerals show that the Luoyang Fe deposit formed in an orogenic setting.
洛阳铁多金属矿床是闽西南晚古生代盆地中一个著名的马坑型矿床。为探讨洛阳马坑型铁矿的成因,对洛阳马坑型铁矿进行了年代学和S-Pb-O-H同位素组成的综合研究。花岗岩的LA-ICP-MS锆石U-Pb年龄和辉钼矿的Re-Os年龄表明,花岗岩的侵位与洛阳矿床的成矿作用在133 ~ 131 Ma之间。H-O和S-Pb同位素组成表明,洛阳矿床成矿物质为岩浆热液源,成矿物质主要来源于上地壳,地幔物质污染程度较低。矿石矿物Pb同位素分析表明,洛阳铁矿形成于造山带。
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引用次数: 5
Geochemical characteristics of gold mineralization of the Huai Kham On deposit, Sukhothai Fold Belt, Northern Thailand 泰国北部素可泰褶皱带淮坎安金矿化地球化学特征
IF 1.4 4区 地球科学 Q2 Earth and Planetary Sciences Pub Date : 2020-09-29 DOI: 10.1111/rge.12246
L. Tangwattananukul, D. Ishiyama, P. Charusiri
The Huai Kham On gold deposit is located in the central part of the Sukhothai Fold Belt, northern Thailand. The Sukhothai Fold Belt represents an accretionary complex formed by subduction and collision between the Indochina and Sibumasu Terranes. There are many small gold deposits in the Sukhothai Fold Belt; however, the styles and formation environments of those gold deposits are not clear. The geology of the Huai Kham On deposit consists of volcanic and volcanosedimentary rocks, limestone, and low‐grade metamorphic rocks of Carboniferous to Triassic age. Gold‐bearing quartz veins are hosted by volcanic and volcanosedimentary rocks. The quartz veins can be divided into four stages. The mineral assemblage of the gold‐bearing quartz veins of Stages I and II comprises quartz, calcite, illite, pyrite, native gold, galena, chalcopyrite, and sphalerite. Quartz veins of Stage III consist of microcrystalline quartz, dolomite, calcite, pyrite, native gold, and chalcopyrite. Veins of Stage IV consist of calcite, dolomite, chlorite, and quartz. Fluid inclusions in quartz veins are classified into liquid‐rich two‐phase (Types IA and IB), carbonic‐aqueous (Type II), and carbonic (Type III) fluid inclusions. The homogenization temperatures of Types IA and II fluid inclusions that are related to the gold‐bearing quartz veins from Stages I to III ranged from 240° to 280°C. The δ18O values of quartz veins of Stages I to III range from +12.9 to +13.4‰, suggesting the presence of a homogeneous hydrothermal solution without temperature variation such as a decrease of temperature during the formation of gold‐bearing quartz veins from Stages I to III in the Huai Kham On gold deposit. Based on the calculated formation temperature of 280°C, the δ18O values of the hydrothermal solution that formed the gold‐bearing quartz veins range from +3.2 to +3.7‰, which falls into the range of metamorphic waters. The gold‐bearing quartz veins of the Huai Kham On deposit are interpreted to be the products of metamorphic water.
淮康安金矿位于泰国北部素可泰褶皱带的中部。素可泰褶皱带有许多小型金矿床;然而,这些金矿床的样式和形成环境尚不清楚。淮康安矿床地质主要由石炭-三叠纪火山岩、火山沉积岩、灰岩和低品位变质岩组成。含金石英脉赋存于火山岩和火山沉积岩中。石英脉可分为四个阶段。第一阶段和第二阶段含金石英脉的矿物组合包括石英、方解石、伊利石、黄铁矿、原生金、方铅矿、黄铜矿和闪锌矿。第三阶段石英脉由微晶石英、白云石、方解石、黄铁矿、原生金和黄铜矿组成。第四阶段的矿脉由方解石、白云石、绿泥石和石英组成。石英脉中的流体包裹体分为富液两相(IA型和IB型)、碳水(II型)和碳水(III型)流体包裹体。ⅰ~ⅲ期与含金石英脉相关的IA型和II型流体包裹体均一温度范围为240 ~ 280℃。ⅰ~ⅲ期石英脉的δ18O值在+12.9 ~ +13.4‰之间,表明淮康安金矿ⅰ~ⅲ期含金石英脉形成过程中存在均匀热液,没有温度降低等温度变化。根据280℃的地层温度计算,形成含金石英脉的热液的δ18O值为+3.2 ~ +3.7‰,属于变质水的范畴。淮康安金矿床含金石英脉被解释为变质水的产物。
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引用次数: 1
Early Miocene metallogenic event formed the Bosawa low‐sulfidation epithermal gold deposit, Northeast Japan arc 早中新世成矿事件形成了日本东北弧渤泽低硫化浅成热液金矿床
IF 1.4 4区 地球科学 Q2 Earth and Planetary Sciences Pub Date : 2020-09-21 DOI: 10.1111/rge.12248
Teruhiro Suzuki, Shota Satori, Yuho Fujimaki, Yasushi Watanabe
There are a number of epithermal Au‐Ag deposits in the Tohoku region of the Northeast Japan arc; however, these deposits have undergone limited exploration for over the past seven decades. This reconnaissance research study of the Bosawa deposit in Akita Prefecture was conducted to support future gold exploration in the Tohoku region. The Bosawa deposit is a vein‐type Au‐Ag deposit, with a production of 42,486 t of ore at 7.01 g/t Au and 14.9 g/t Ag recorded for the period from 1936 to 1957; mining started in the 18th century. The deposit consists of the Ohgiri vein system, which is hosted in felsic volcanic rocks of the Early Miocene Katsurabuchi Formation. The study included geological prospecting, ore description, K‐Ar dating, and fire assay analyses. The deposit is characterized by (a) strongly silicified host lapilli tuff fringed by pyrite‐adularia‐illite alteration; (b) presence of sulfide‐poor banded quartz veins with adularia; (c) abundance of bladed quartz in veins, pseudomorphs after bladed calcite; (d) presence of colloform opal texture in veins; and (e) simple ore mineralogy consisting of gold and argentite. These characteristics are typical of low‐sulfidation epithermal Au deposits. The K‐Ar age of adularia (19.33 ± 0.45 Ma) indicates that mineralization at Bosawa is distinctly older than the ages of other epithermal deposits in the Tohoku region but similar to the age of the initial mineralization episode of the Sado and Tsurushi deposits (24.4–22.1 Ma), Japan's second largest gold producer. This mineralization age coincides with the start of rifting of the Northeast Japan arc and separation from the Asian continent. As the felsic rocks related to this rifting event are widespread in the arc, and some are associated with epithermal gold deposits, the confirmation of typical low‐sulfidation style of mineralization in the Early Miocene provides evidence for a previously unrecognized metallogenic event in the Tohoku region.
在日本东北弧的东北地区有大量的浅成热液型金银矿床;然而,在过去的70年里,这些矿床经历了有限的勘探。对秋田县Bosawa矿床进行了勘查研究,为今后在东北地区进行金矿勘探提供了依据。Bosawa矿床为脉状金银矿床,1936 ~ 1957年记录的产量为42486 t, Au为7.01 g/t, Ag为14.9 g/t;采矿始于18世纪。矿床为大树脉系,赋存于早中新世胜口组长英质火山岩中。该研究包括地质勘探、矿石描述、K - Ar定年和火焰分析。该矿床的特征为:(a)强硅化的寄主石堆凝灰岩,外围是黄铁矿-亚黄铁矿-伊利石蚀变;(b)含硫化物的带状石英脉;(c)叶脉中有丰富的叶状石英,叶状方解石后有假晶;(d)静脉中存在胶状蛋白石织构;(e)由金和辉钼矿组成的简单矿石矿物学。这些特征是低硫化浅成热液型金矿的典型特征。其中,Bosawa的K - Ar年龄(19.33±0.45 Ma)表明,Bosawa的成矿年龄明显高于东北地区其他浅成热液矿床,但与日本第二大金矿Sado和Tsurushi矿床的初始成矿年龄(24.4-22.1 Ma)相似。这一成矿时代与日本东北弧的裂陷开始和与亚洲大陆的分离相吻合。由于与此裂谷事件相关的长英质岩在弧内分布广泛,其中一些与浅成热液型金矿床有关,早中新世典型低硫化型成矿作用的确认为东北地区以前未被认识的成矿事件提供了证据。
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引用次数: 1
Hydrothermal activity in the Obiro deposit embedded in the Tagawa acidic rocks, Uetsu region, NE Japan 日本东北部上津地区田川酸性岩中Obiro矿床的热液活动
IF 1.4 4区 地球科学 Q2 Earth and Planetary Sciences Pub Date : 2020-08-18 DOI: 10.1111/rge.12244
Yuki Nakajima, Y. Izumino, Shin‐ichi Kagashima, K. Nakashima
The Obiro deposit is located in the Tagawa Acidic Rocks (AR), Uetsu region, NE Japan. The Tagawa AR is composed of a volcanic phase of dacitic welded tuff and a plutonic phase of porphyritic granodiorite. Drill core and ore samples were collected from the deposit and examined by XRD, EPMA, and microthermometry. The drill core samples have suffered pervasively from sericite (illite) alteration, whereas pinkish K‐feldspar alteration halo occur close to veins. The results of EPMA and microthermometry is interpreted as that the magnatic‐hydrothermal fluids has changed as follows; the granodioritic magma intruded at about 1.0 kb and 700°C near the water‐saturated granite solidus; after cooling to about 500°C the fluids boiled according to a change in the pressure regime from lithostatic to hydrostatic; mixing with meteoric water led to sulfide mineralization at around 400°C or less. The main reasons for the mineralization in the Obiro deposit are as follows; the oxidized magma intruded at a shallower level, and thereafter hydrothermal fluids were boiled, resulting in a saline fluid. The saline fluid then dissolved metals such as Pb, Zn, Cu, and Bi, and these metals precipitated during cooling accompanied by dilution of the meteoric water and increasing pH, resulting in decreasing solubility.
Obiro矿床位于日本东北部上津地区的田川酸性岩(AR)。田川地区由火山期的英安质焊接凝灰岩和深裂期的斑岩花岗闪长岩组成。从矿床中采集钻孔岩心和矿石样品,并采用XRD、EPMA和显微测温法进行了检测。钻芯样品普遍遭受绢云母(伊利石)蚀变,而粉红色的钾长石蚀变晕出现在靠近脉的地方。EPMA和显微测温结果表明,岩浆热液流体发生了如下变化;花岗闪长岩岩浆在700℃、1.0 kb左右侵入水饱和花岗岩固体附近;冷却至约500℃后,流体根据从静压到静压的压力状态变化而沸腾;与大气水混合导致硫化物矿化温度在400°C左右或更低。奥比罗矿床成矿的主要原因有:氧化岩浆侵入较浅的层位,随后热液流体沸腾,形成含盐流体。盐水溶解了铅、锌、铜和铋等金属,这些金属在冷却过程中沉淀下来,伴随着大气水的稀释和pH值的增加,导致溶解度降低。
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引用次数: 0
Geology and inclusion studies on the genesis of the Baolun gold deposit in Hainan Province, South China 海南宝伦金矿床成因地质与包裹体研究
IF 1.4 4区 地球科学 Q2 Earth and Planetary Sciences Pub Date : 2020-07-16 DOI: 10.1111/rge.12243
Liangliang Yu, Deru Xu, Weixin Chen, Boyou Zhang, L. Tian, Q. Shan
The late Triassic Baolun gold deposit hosted by Silurian phyllites is a large‐scale high‐grade gold deposit in Hainan Island, South China. The ores can be classified into quartz‐vein dominated type and less altered rock type. Three mineralization stages were recognized by mineral assemblages. The early stage, as the most important mineralization stage, is characterized by a quartz–native gold assemblage. The muscovite−quartz−pyrite−native gold assemblage is related to the intermedium mineralization stage. In late mineralization stage, native gold and Bi‐bearing minerals are paragenetic minerals. Microthermometry analyses show that the early mineralization stage is characterized by two types of fluid inclusions, including CO2‐rich inclusions (C‐type) and aqueous inclusions (W‐type). C‐type inclusions homogenize at 276–335°C with an averaged value of 306°C and have salinities of 1.0–10.0 wt% NaCl equivalent (mean value of 4.9 wt% NaCl equivalent). W‐type inclusions homogenize at 252–301°C (mean value of 278°C) with salinity of 4.0–9.7 wt% NaCl equivalent (mean value of 7.4 wt% NaCl equivalent). In intermedium mineralization stage, C‐type and W‐type inclusions homogenize at 228–320°C (mean value of 283°C) and 178–296°C (mean value of 241°C), with salinities of 2.4–9.9 wt% NaCl equivalent (mean value of 6.5 wt% NaCl equivalent) and 3.7–11.7 wt% NaCl equivalent (mean value of 7.7 wt% NaCl equivalent), respectively. No suitable mineral, such as quartz or calcite, was found for fluid inclusion study from late mineralization stage. In contrast, only aqueous inclusions were found from post‐ore barren veins, which yielded lower homogenization temperatures ranging from 168–241°C (mean value of 195°C) and similar salinities (2.6–12.6 wt% NaCl equivalent with averaged value of 7.2 wt% NaCl equivalent). The different homogenization temperatures and similar salinities of C‐type and W‐type from each mineralization stage indicate that fluid immiscibility and boiling occurred. The Baolun gold deposit was precipitated from a CO2‐bearing mesothermal fluid, and formed at a syn‐collision environment following the closure of the Paleo‐Tethys.
晚三叠世宝伦金矿床为志留系千层岩赋存物,是海南岛的一个大型高品位金矿床。矿石可分为石英脉为主型和少蚀变岩型。根据矿物组合划分出3个成矿阶段。早期是最重要的成矿阶段,以石英-原生金组合为特征。白云母-石英-黄铁矿-金矿组合与中成矿阶段有关。在成矿晚期,原生金矿物与含铋矿物为共生矿物。显微测温分析表明,成矿早期主要有两类流体包裹体,即富CO2包裹体(C型)和含水包裹体(W型)。C型包裹体在276-335℃均匀化,平均值为306℃,盐度为1.0-10.0 wt% NaCl当量(平均值为4.9 wt% NaCl当量)。W型包裹体在252-301°C(平均值278°C)下均匀化,盐度为4.0-9.7 wt% NaCl当量(平均值7.4 wt% NaCl当量)。在中矿化阶段,C型和W型包裹体在228 ~ 320℃(平均值283℃)和174 ~ 296℃(平均值241℃)均匀化,盐度分别为2.4 ~ 9.9 wt% NaCl当量(平均值6.5 wt% NaCl当量)和3.7 ~ 11.7 wt% NaCl当量(平均值7.7 wt% NaCl当量)。未发现石英、方解石等适合成矿晚期流体包裹体研究的矿物。相比之下,仅在矿后无矿脉中发现了含水包裹体,其均质温度较低,范围为168-241°C(平均值为195°C),盐度相似(2.6-12.6 wt% NaCl当量,平均值为7.2 wt% NaCl当量)。各成矿阶段均质温度不同,C型和W型矿化度相近,表明成矿过程中存在流体不混溶和沸腾现象。宝伦金矿床由含CO2的中温流体沉积而成,形成于古特提斯闭合后的同步碰撞环境。
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引用次数: 1
Setting, sulfur isotope variations, and metamorphism of Jurassic massive Zn‐Pb‐Ag sulfide mineralization associated with arc‐type volcanism (Skra, Vardar zone, Νorthern Greece) 与弧型火山作用相关的侏罗纪块状Zn - Pb - Ag硫化物矿化背景、硫同位素变化及变质作用(Skra, Vardar带,Νorthern希腊)
IF 1.4 4区 地球科学 Q2 Earth and Planetary Sciences Pub Date : 2020-06-29 DOI: 10.1111/rge.12241
N. Skarpelis
Massive Zn‐Pb‐Ag sulfide mineralization appears conformable with felsic volcanism, developed in an Upper Jurassic volcanic arc to the Southwest (SW) of the Serbo‐Macedonian continent in Northern Greece. The host volcanic sequence of the mineralization comprises mylonitized rhyolitic to rhyodacitic lavas, pyroclastics, quartz‐feldspar porphyries, and cherty tuffs. A “white mica—quartz—pyrite” mineral assemblage characterizes the volcanic rocks in the footwall and hanging‐wall of massive sulfide ore layers, formed as a result of greenschist‐grade regional metamorphism on “clay‐quartz‐pyrite” hydrothermal alteration haloes. Massive ore lenses are usually underlain by deformed Cu‐pyrite and quartz‐pyrite stockworks. Most of the sulfide ore bodies have proximal‐type features. Ductile deformation and regional metamorphism have transformed many of the stockwork structures. The mineralization is characterized by high Zn, Pb, and Ag contents, while Cu and critical metals are low. Primary depositional textures, for example, layering, clastic pyrite, colloform, and atoll textures were identified. The overall textural features of the mineralization indicate it has undergone mechanical deformation. The most prominent features of the effects of metamorphism, folding and shearing, are modification of the ore body morphology toward flattened and boudinage structures and transformation of the ore textures toward the dominance of planar fabrics. Sulfur isotope analyses of sulfides along with textural observations are consistent with a dual source of sulfide sulfur. Sulfur isotope values for sphalerite, non‐colloform pyrite, galena, and chalcopyrite fall in a limited range from −1.6 to +4.8‰ (mean δ34S + 2‰), indicating a hydrothermal source derived from the reduction of coeval seawater sulfate in the convective system. Pyrites with colloform and atoll textures are characterized by a 34S depletion, indicating a bacterial reduction of coeval seawater sulfate. The morphology of ore beds, the mineralogy, sulfide textures, and ore chemistry along with the petrology and tectonic setting of the host rocks can be attributed to typical of a bimodal‐felsic metallogenesis. Although similar in many respects to classic Kuroko‐type volcanogenic massive sulfide mineralization, it has some atypical features, like the absence of barite ore, which is possibly a result of significant temporal depletion in sulfate due to bacterial reduction, a conclusion supported by the widespread occurrence of colloidal and atoll textures of pyrite.
大量的锌-铅-银硫化物矿化与长英质火山作用一致,形成于希腊北部塞尔维亚-马其顿大陆西南(SW)的上侏罗世火山弧中。成矿的主火山序列包括糜棱岩化流纹岩至流纹酸熔岩、火山碎屑、石英长石斑岩和硅质凝灰岩。“白色云母-石英-黄铁矿”矿物组合是块状硫化物矿层下盘和上盘火山岩的特征,是绿片岩级区域变质作用在“粘土-石英-黄铁矿”热液蚀变晕上形成的。块状矿石透镜体通常被变形的铜-黄铁矿和石英-黄铁矿网所覆盖。多数硫化物矿体具有近端型特征。韧性变形和区域变质作用改变了许多网状构造。矿化特征为锌、铅、银含量高,铜和关键金属含量低。确定了层状、碎屑黄铁矿、胶状和环礁等原始沉积结构。矿化的整体构造特征表明其经历了机械变形。变质作用、褶皱作用和剪切作用的最突出特征是使矿体形态向扁平、破碎构造转变,使矿体结构向平面组构为主转变。硫化物的硫同位素分析以及结构观测与硫化物硫的双重来源一致。闪锌矿、非胶状黄铁矿、方铅矿和黄铜矿的硫同位素值在- 1.6 ~ +4.8‰(平均δ34S + 2‰)范围内有限下降,表明其为对流系统中同期海水硫酸盐还原形成的热液源。具有胶状和环礁结构的黄铁矿具有34S耗损特征,表明同时期海水硫酸盐的细菌还原。矿床的形态、矿物学、硫化物结构和矿石化学以及寄主岩石的岩石学和构造环境可归因于典型的双峰-长英质成矿作用。虽然在许多方面与经典的Kuroko型火山成因块状硫化物矿化相似,但它也有一些非典型特征,比如缺乏重晶石矿石,这可能是由于细菌还原导致硫酸盐的显著时间损耗的结果,这一结论得到了广泛存在的黄铁矿胶体和环礁结构的支持。
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引用次数: 1
Greetings from the editorial office 编辑部的问候
IF 1.4 4区 地球科学 Q2 Earth and Planetary Sciences Pub Date : 2020-06-25 DOI: 10.1111/rge.12236
Yasushi Watanabe
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引用次数: 0
Mineralization age and sources of ore‐forming material of the Nanmushu Zn‐Pb deposit in the Micangshan Tectonic Belt at the northern margin of the Yangtze Craton, China: Constraints from Rb‐Sr dating and Sr‐Pb isotopes 扬子克拉通北缘米沧山构造带南木树锌Pb矿床成矿年龄及成矿物质来源:Rb - Sr测年和Sr - Pb同位素约束
IF 1.4 4区 地球科学 Q2 Earth and Planetary Sciences Pub Date : 2020-06-25 DOI: 10.1111/rge.12235
Zhi-Min Song, Cuihua Chen, Yulong Yang, Yan Zhang, L. Yin, Hongzhi Li
The Nanmushu Zn‐Pb deposit, hosted by the Neoproterozoic Dengying Formation dolostone, is located in the eastern part of the Micangshan tectonic belt at the northern margin of the Yangtze Craton, China. This study involves a systematic field investigation, detailed mineralogical study, and Rb‐Sr and Pb isotopic analyses of the deposit. The results of Rb‐Sr isotopic dating of coexisting sphalerite and galena yield an isochron age of 486.7 ± 3.1 Ma, indicating the deposit was formed during the Late Cambrian to Early Ordovician. This mineralization age is interpreted to be related to the timing of destruction of the paleo‐oil reservoir in the Micangshan tectonic belt. All initial 87Sr/86Sr ratios of sphalerite and galena (0.70955–0.71212) fall into the range of the Mesoproterozoic Huodiya Group basement rocks (0.70877–0.71997) and Dengying Formation sandstone (0.70927–0.71282), which are significantly higher than those of Cambrian Guojiaba Formation limestone (0.70750–0.70980), Cambrian Guojiaba Formation carbonaceous slate (0.70766–0.71012), and Neoproterozoic Dengying Formation dolostone (0.70835–0.70876). Such Sr isotope signatures suggest that the ore strontium was mainly derived from a mixed source, and both of the Huodiya Group basement rocks and Dengying Formation sandstone were involved in ore formation. Both sphalerite and galena are characterized by an upper‐crustal source of lead (206Pb/204Pb = 17.849–18.022, 207Pb/204Pb = 15.604–15.809, and 208Pb/204Pb = 37.735–38.402), and their Pb isotopes are higher than, but partly overlap with, those of the Huodiya Group basement rocks, but differ from those of the Guojiaba and Dengying Formations. This suggests that the lead also originated from a mixed source, and the Huodiya Group basement rocks played a significant role. The Sr and Pb isotopic results suggest that the Huodiya Group basement rocks were one of the most important sources of metallogenic material. The geological and geochemical characteristics show that the Nanmushu Zn‐Pb deposit is similar to typical Mississippi Valley type, and the fluid mixing may be a reasonable metallogenic mechanism for Nanmushu Zn‐Pb deposit.
南木树铅锌矿床位于扬子克拉通北缘米仓山构造带东段,赋存于新元古代灯影组白云岩中。本研究包括系统的野外调查、详细的矿物学研究以及矿床Rb - Sr和Pb同位素分析。同时存在的闪锌矿和方铅矿的Rb - Sr同位素定年结果显示,等时线年龄为486.7±3.1 Ma,表明矿床形成于晚寒武世至早奥陶世。这一成矿年龄与米仓山构造带古油藏的破坏时间有关。闪锌矿和方铅矿的初始87Sr/86Sr比值(0.70955 ~ 0.71212)均落在中元古代火崖群基底岩(0.70877 ~ 0.71997)和灯影组砂岩(0.70927 ~ 0.71282)的范围内,显著高于寒武系郭家坝组灰岩(0.70750 ~ 0.70980)、寒武系郭家坝组碳质板岩(0.70766 ~ 0.71012)和新元古代灯影组白云岩(0.70835 ~ 0.70876)。Sr同位素特征表明矿石锶主要为混合来源,火底崖群基底岩和灯影组砂岩均参与了成矿作用。闪锌矿和方铅矿均具有上地壳铅源特征(206Pb/204Pb = 17.849 ~ 18.022, 207Pb/204Pb = 15.604 ~ 15.809, 208Pb/204Pb = 37.735 ~ 38.402),其铅同位素均高于火崖群基底岩石,但与郭家坝组和灯影组基底岩石的铅同位素有一定的重叠。这表明铅的来源也是混合的,火崖群基底岩在其中起了重要作用。Sr、Pb同位素结果表明,火崖群基底岩是其重要的成矿物质来源之一。地质地球化学特征表明,南木树铅锌矿床具有典型的密西西比河谷型成矿特征,流体混合作用可能是南木树铅锌矿床的合理成矿机制。
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引用次数: 2
Mineralization events in the Xiaokele porphyry Cu (–Mo) deposit, NE China: Evidence from zircon U–Pb and K‐feldspar Ar–Ar geochronology and petrochemistry 中国东北小柯勒斑岩型铜(钼)矿床成矿事件:锆石U-Pb和钾长石Ar-Ar年代学和岩石化学证据
IF 1.4 4区 地球科学 Q2 Earth and Planetary Sciences Pub Date : 2020-03-30 DOI: 10.1111/rge.12233
Yonggang Sun, Bile Li, F. Sun, Q. Ding, Baiyi Wang, Yu-jin Li, Kun Wang
The Great Xing'an Range (GXR), Northeast (NE) China, is a major polymetallic metallogenic belt in the eastern segment of the Central Asian Orogenic Belt. The newly discovered Xiaokele porphyry Cu (–Mo) deposit lies in the northern GXR. Field geological and geochronological studies have revealed two mineralization events in this deposit: early porphyry‐type Cu (–Mo) mineralization, and later vein‐type Cu mineralization. Previous geochronological studies yielded an age of ca. 147 Ma for the early Cu (–Mo) mineralization. Our 40Ar/39Ar dating yielded 40Ar/39Ar plateau ages of 124.8 ± 0.4 to 124.3 ± 0.4 Ma on K‐feldspar in altered Cu‐mineralized diorite porphyrite dikes that represent the overprinting vein‐type Cu mineralization, consistent with zircon U–Pb ages of the diorite porphyrite (126.4 ± 0.5 to 125.0 ± 0.5 Ma). The Cr and Ni contents and Mg# of the Xiaokele diorite porphyrites are high. The diorite porphyrites at Xiaokele are enriched in light rare‐earth elements (REEs), and large‐ion lithophile elements (e.g., Rb, Ba, and K), are depleted in heavy REEs and high‐field‐strength elements (e.g., Nb, Ta, and Ti), and have weak negative εHf(t) values (+0.29 to +5.27) with two‐stage model ages (TDM2) of 1,164–845 Ma. Given the regional tectonic setting in Early Cretaceous, the ore‐bearing diorite porphyrites were likely formed in an extensional environment related to lithospheric delamination and asthenospheric upwelling induced by subduction of the Paleo‐Pacific Plate. These tectonic events caused large‐scale magmatic activity, ore mineralization, and lithospheric thinning in NE China.
中国东北大兴安岭是中亚造山带东段的一个重要多金属成矿带。新发现的小柯勒斑岩型铜(钼)矿床位于GXR北部。野外地质和年代学研究揭示了该矿床的两个成矿事件:早期斑岩型铜(-Mo)成矿和晚期脉状型铜成矿。先前的地质年代学研究表明,早期铜(-钼)成矿年龄约为147 Ma。40Ar/39Ar测年结果显示,蚀变铜矿化闪长岩斑岩脉中钾长石的40Ar/39Ar高原年龄为124.8±0.4 ~ 124.3±0.4 Ma,代表了覆印脉型铜矿化,与闪长岩斑岩的锆石U-Pb年龄(126.4±0.5 ~ 125.0±0.5 Ma)一致。小柯勒闪长斑岩中Cr、Ni含量高,Mg#含量高。小科勒闪长玢岩富集轻稀土元素(ree)和大离子亲石元素(Rb、Ba、K),贫重稀土元素和高场强元素(Nb、Ta、Ti), εHf(t)值为弱负(+0.29 ~ +5.27),两阶段模式年龄(TDM2)为1164ma ~ 845ma。考虑到早白垩世的区域构造背景,含矿闪长玢岩可能形成于古太平洋板块俯冲引起的岩石圈拆沉和软流圈上升流的伸展环境。这些构造事件导致了中国东北地区大规模的岩浆活动、矿化和岩石圈变薄。
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引用次数: 11
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Resource Geology
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