Characteristics of Breccias and C-O-Sr-S Isotope Geochemistry of the Duocaima Pb-Zn Deposit in Tuotuohe, Qinghai Province: Implications for the Ore-forming Process

The Duocaima carbonate-hosted Pb-Zn deposit is a newly found large deposit in the southern area of Qinghai Province.In this paper, the characteristics, genesis, significance to Pb-Zn mineralization of the widely developed breccias, and the ore-forming process have been carefully studied based on geological documentation of drilling holes, microscopic observations of petrography and microstructure and some stable isotope measurements.Based on the compositions of the clast and matrix, the breccias can be classified into three types： limestone clasts cemented by marl; limestone clasts with fine-grained calcareous materials; and limestone clasts cemented by hydrothermal calcite.The mineralization in the first type of breccia is weak, whereas it is strong in the latter two types of breccias.According to the locations of occurrence and structural characteristics of the breccias along with the relationship between the breccias and mineralization, part of the limestone clasts that are cemented by marl and outcrop in the contact zone between the Wudaoliang Formation（Nw） and the underlying Jiushidaoban Formation（Pj） are attributed to synsedimentary fault-genetic breccia, whereas the last of the limestone clasts that are cemented by marl and developed in the Jiushidaoban Formation（Pj） are attributed to the breccia generated by karst cave collapse; the limestone clasts with fine-grained calcareous materials and the limestone clasts cemented by hydrothermal calcite are attributed to breccia formed by hydrothermal dissolution.The breccia formed by karst collapse had consistently evolved for a long period of time, while the breccias with other origins were formed around the period of mineralization（i.e., about or slightly later than 20–16 Ma）.The breccia generated by karst cave collapse and hydrothermal dissolution are somewhat related; the formation of the breccia from karst cave collapse provided open space for the later mineralization and reaction between hydrothermal fluids and host rocks, and the subsequent strong dissolution by hydrothermal fluids transformed some of the breccia formed earlier by karst cave collapse.Meanwhile, carbonate host rocks with breccias and brecciaed mineralization can be a potential sign of Mississippi Valley Type（MVT） deposits and important indicators for regional mineral exploration.The δ13CV-PDB, δ18OVSMOW, and 87Sr/86 Sr values of hydrothermal calcite in the Duocaima deposit range from 4.3‰ to 7.1‰, 14.9‰ to 20.1‰, and 0.707494 to 0.708185, respectively; the δ13CV-PDB, δ18OV-SMOW, and 87Sr/86 Sr values of the host limestones of the Jiushidaoban Formation range from 3.6‰ to 5.3‰, 18.0‰ to 20.5‰, and 0.707372 to 0.707945, respectively.The δ13CV-PDB and 87Sr/86 Sr values of hydrothermal calcite and limestone are similar, indicating single sources of C and Sr in this deposit, with the likely source being the limestone of the Jiushidaoban Formation.The minor scattering of the δ18OV-SMOW values suggests that different O isotope fluids underwent the isotope exchange reaction.The C-O-Sr isotope characteristics indicate that the host limestones experienced a dissolution and precipitation process during mineralization, which is beneficial to improving the porosity of host rocks and promoting the precipitation of metal sulfides.The δ34SV-CDT value of the breccia-type mineralization sulfides ranges from-30.4‰ to-0.3‰; that is, the δ34SV-CDT value is negative with considerable variation, illustrating that during the breccia-type mineralization process, the bacteriogenic reduction of sulfates provided the vast majority of sulfur, whereas the thermochemical reduction of sulfates was relatively unimportant.The brecciation that occurred as a result of karst cave collapse was mainly generated by the dissolution of groundwater; however, the brecciation related to hydrothermal dissolution and mineralization processes were caused by mixing of different fluids.

Tellurium-Gold Mineralization Related to Cryptoexplosive Breccias within Volcanic Pipe in Zhuojiazhuang Gold Deposit,Shandong Province, China

Zhuojiazhuang gold deposit (ZGD) is the most enriched breccia pipe type gold deposit in East China, resulted from cryptoexplosion related to alkalinic magmatism and orebearing fluid filling. The ZGD is a small-sized mine with over 5 tons of gold reserves and grade of 156g/t in average and the highest 2 728 g/t as known. In addition, tellurium and silver are also valuable.The mineralized breccia pipe is cylinder-like in shape with 15 m long and 10 m wide and controlled by intersection ofNW and EW trend faults. Mining level has reached 170 m below the surface, but the whole pipe mineralization is still stable. Mineralization commonly occurs within the cements of breccias. Gold ores consist of hydrothermal breccia ore, shatteredbreccia ore and cataclastic ore. From the center of the ore body outwards, there is the transition from hydrothermal breccia toshattered breccia and then to cataclastic ores. According to composition and amount of the cements, the hydrothermal brecciaores can further be divided into three subtypes: sulfides cemented, hydrothermal mineral cemented and magma cemented.The content of gold is closely related to the types of the cements. The grade of the sulfide cemented breccia is the highestone, usually more than 1 000 g/t, and the known maximum grade is 2 728 g/t. The composition of the shattered breccia ismainly dioritic porphyrite and cemented by hydrothermal minerals, the grade ranges from ten to several tens g/t. The catsclastic ores are mainly composed of dioritic porphyrite, syenitic porphyry, as well as carbonate with mineralized veins, and the grade is only 35 g/t.Major ore minerals consist of pyrite, native tellurium, sphalerite, with minor calaverite, galena and altaite. Gangueminerals are composed of microcrystalline quartz, decktite and fluorite, with minor sericite and calcite. Brecciated and disseminited structures are main structures of ores. Four ore-forming stages are defined: microcrystalline quartz-pyrite stage,microcrystalline quartz-polymetal sulfides stage, quartz-adular stage and dickite stage. Wall rock alteration is characterized bysilicification, sericitization, adularization and fluoritization.The enrichment of tellurium may indicate that the ore-forming fluid was of a deep origin from upper mantle or lower crust. Mineral assemblage of microcrystalline quartz, fluorite, adularia and dickite suggest a relatively low-temperature forming condition. An extensive suite of elements, including Au, Ag, Te, Hg, Sb, As, Mo, F, Zn, and Tl, is significantly enriched in mineralized rocks. They can be geochemical indicators for exploration in the study area.Comprehensive studies show that the Zhuojiazhuang gold deposit is a type of sericite-adular gold deposit, belongs to epithermal gold deposits, or can be classified into alkali gold deposit series.

准噶尔盆地红车断裂带石炭系重新认识及油气成藏特征

准噶尔盆地红车断裂带石炭系岩性、内幕结构及接触关系复杂,为建立其地层层序,以野外露头建立的石炭系地层系统为基础,通过岩性、电性和地震属性精细地层标定,依据岩性组合特征、地震波组特征和地层接触关系进行综合分析,将西北缘后山石炭系地层系统引入盆内进行井下地层对比,建立石炭系层序剖面并开展精细地层划分与对比,在石炭系地层格架基础上开展优势岩相分析。结果表明:(1)准噶尔盆地盆内井下钻揭地层为上石炭统,由新到老依次为阿腊德依克赛组、哈拉阿拉特组和成吉思汗山组,整体向西超覆抬升,呈现“东西分带、南北分块”构造格局。(2)成吉思汗山组主要发育爆发相火山角砾岩,受推覆作用影响,阿腊德依克赛组和哈拉阿拉特组超覆尖灭,南部爆发相剥蚀减少,主体发育火山沉积相和碎屑岩沉积相。(3)主要含油层为成吉思汗山组和哈拉阿拉特组,南部火山角砾岩及局部安山玄武岩为油气有利指向区。

内蒙古多伦县义盛店火山岩型铀多金属矿综合信息找矿模型

【研究目的】义盛店铀多金属矿(化)体赋存于西干沟破火山机构附近的晚侏罗世满克头鄂博期次火山岩体中,主要受NW-NNW向断裂构造与次流纹岩体内隐爆角砾岩带的结合部位控制,研究并建立该矿床综合信息找矿模型对指导成矿带找矿意义重大。【研究方法】本文在研究该地区铀成矿地质条件,成矿地质体、成矿构造与成矿结构面、成矿作用特征标志的基础上,结合矿区土壤地球化学特征和激电、伽马能谱、活性炭及静电α异常特征信息开展了系统综合研究工作。【研究结果】通过研究建立了矿区地质找矿模式,归纳并总结了矿区成矿主要受火山构造控制和土壤地球化学异常区与低电阻率高极化体异常及具有深穿透放射性形成的几何形态异常等物化探找矿标志,构建了该区地质-地球化学-地球物理“三位一体”的综合信息找矿模型。【结论】研究认为在义盛店矿区断裂破碎带、次火山岩接触带与隐爆角砾岩构造的叠加部位,地球化学异常与地球物理异常区相吻合地段,存在形成中-大型铀多金属矿床的潜力,并应用模型指导找矿取得了新突破。

贵州省天柱县大河边地区寒武系乌训组滑塌建造的物源及其意义

沉积岩中普遍发育滑塌滑移建造。贵州天柱大河边地区寒武系第二统乌训组即普遍发育滑塌滑移建造,通过地质调查分析,可见滑塌滑移角砾岩建造、瘤状灰岩建造、散布于炭质粘土岩中的“钙质结核”和灰岩中的泥岩脉,以及一系列滑移褶皱褶曲等软沉积物变形构造等类型。根据滑塌滑移角砾岩建造中的鲕粒灰岩角砾和乌训组沉积建造处于大陆斜坡环境的古地理背景分析,滑塌滑移角砾岩建造中的鲕粒灰岩角砾应来源于乌训组北西侧处于台地边缘相的清虚洞组,结合灰岩中的泥岩脉即典型震积泥岩脉现象,综合认为,乌训组普遍发育的各种类型滑塌滑移角砾岩建造和其它变形建造,系地震营力及其导致的滑塌滑移事件作用的结果。

安徽枞阳县黄龙桥地区隐爆角砾岩筒特征及其与铀成矿关系

安徽枞阳黄龙桥地区隐爆角砾岩筒地处庐枞盆地黄梅尖A型花岗岩体内,是岩体内发育的规模最大、最为典型的隐爆角砾岩筒。文章在详细的野外地质调查、物化探测量和钻孔岩心地质编录的基础上,通过显微岩石学、元素地球化学特征研究,分析其地质特征并探讨其与铀成矿的关系。分析研究表明:隐爆角砾岩具有角砾成分杂、隐爆作用强度大、“隐爆源”埋藏深特点,其自身并不含有铀矿化现象,铀元素平均含量远远低于石英正长岩;ΣREE为293.16×10^(-6)~453.45×10^(-6),LREE/HREE为6.71~11.00,δCe为0.89~1.02,δEu为0.46~0.57,呈现较明显的负Eu异常,稀土元素配分模式呈右倾斜型,具有轻稀土分馏明显,重稀土分馏不明显的特点;隐爆角砾岩内部发育的大量赤铁矿形成于岩浆“隐爆”作用之前,铀成矿作用发生在隐爆角砾岩筒形成之后,推测隐爆角砾岩爆发时间在124~115 Ma;隐爆角砾岩筒主要为铀成矿提供了重要的导矿通道,外围具有较好的铀矿找矿潜力,而其深部具有寻找铁矿的潜力。

液压成因含矿构造主要特征——以华南热液钨矿和铀矿为例

液压致裂是整个地壳−岩石圈范围内一种重要的变形破裂方式,也是一些热液矿床的重要含矿构造。通过分析液压致裂构造的形成机制和液压成因含矿构造的类型(液压致裂型和液压撑开型),以华南地区典型热液钨、铀矿为例,基于野外精细调查,明确了包括石门寺钨矿、行洛坑钨矿和邹家山铀矿等的液压成因含矿构造的基本特征。新生性液压致裂含矿构造的主要特征表现为形态复杂(有弧形、分叉树枝形、放射状、菊花形和蟹腿状等)、规模较小、宏观力学性质以张性破裂为主、走向和倾向多变、方向性不明显、仅局部区域发育优势方位、常伴生有热液隐爆角砾岩;因此,可以从弧形分叉或不规则形态、总体较小规模、产状多向性、分布不均匀性和伴生热液隐爆角砾岩这5个标志来识别液压致裂含矿构造。对比分析液压致裂含矿构造与应力致裂含矿构造的差异认为,液压致裂含矿构造发育比较局限,而液压撑开型含矿构造相对普遍,热液蚀变分带与该含矿构造是液压致裂还是应力致裂无明显相关性;压性成因构造在成矿期表现出的张性力学性质有些是成矿流体超压作用的结果,而并非区域构造应力场的改变;液压致裂导致的断裂末端的扩展破裂与成矿流体的耦合作用为成矿末端效应的构造控制机制。

云南开远市吉德金矿地质特征及成矿模式

吉德金矿矿体主要呈似层状、透镜状产于峨眉山玄武岩与下伏灰岩岩溶不整合面、玄武质火山碎屑岩夹层及次级构造破碎带中,有红土型和岩溶角砾岩型两种类型,金以微粒自然金为主,目前矿床规模较小、地质研究程度较低。通过总结成矿规律、构建成矿模式,对矿区及外围寻找红土型和岩溶角砾岩型金矿具有指导作用。

西藏拿若铜(金)矿床隐爆角砾岩对成矿时代的约束

【研究目的】拿若矿床是多龙矿集区4个超大型矿床之一,由斑岩型和角砾岩型矿体组成。斑岩型矿体研究资料丰富,角砾岩矿体研究程度较浅,隐爆作用与成矿作用的时代关系还缺乏详细的研究。隐爆角砾岩整体呈筒状产出,角砾成分为长石石英砂岩和花岗闪长斑岩,胶结物成分主要为岩粉。【研究方法】本次研究旨在通过年代学证据探讨隐爆角砾岩形成与成矿的时代关系。【研究结果】锆石矿物学显示花岗闪长斑岩(NR1)锆石边部发生溶蚀边,震荡环带减弱,未彻底重结晶;胶结物(NR2)锆石结晶较好,震荡环带清晰。两种样品的锆石微量元素特征显示,两期岩浆源区均为陆壳环境;稀土配分曲线均较陡,富集重稀土,亏损轻稀土;具有显著的正Ce异常和负Eu异常。LA-ICP-MS锆石U-Pb定年结果显示,花岗闪长斑岩的锆石206Pb/238U年龄为117.3~125.4 Ma,加权平均年龄为(120.8±1.4)Ma,成岩时间在120.8 Ma左右;胶结物的锆石206Pb/238U年龄为113.5~119.9 Ma,加权平均年龄为(116.4±1.2)Ma,隐爆时代在116.4 Ma左右。【结论】拿若矿床共发生两期成岩作用,分别为~120 Ma和~117Ma。拿若矿床成矿作用发生在116~117 Ma,而非~120 Ma。根据年代学证据认为,成矿作用和隐爆作用受同期岩浆作用控制,隐爆作用在前而成矿作用在后,岩浆演化在时间和空间上存在差异。

广西水汶盆地晚白垩世火山角砾岩锆石U-Pb年代学及其地质意义

利用锆石U-Pb年代学和岩相学对广西水汶盆地上白垩统西垌组下段火山角砾岩的形成时代、锆石特征和角砾来源进行了研究,并探讨了它们的地质意义。该火山角砾岩主要由大量砂岩和变质砂岩角砾、浆屑、玻璃质和细小长英质矿物组成。锆石U-Pb定年结果主要集中在418~469 Ma,较年轻的为107、104和90 Ma;锆石Th/U值均大于0.1,且稀土元素球粒陨石标准化配分模式具有明显的Ce正异常和Eu负异常,表明其为岩浆成因锆石。锆石形态研究显示,年龄老的锆石磨圆度较好,环带不清晰;年龄新的锆石磨圆度较差,环带较发育。区域地质资料显示,原来划分为新元古界的变质砂岩获得的碎屑锆石U-Pb年龄为393~456 Ma。因此,本文认为上白垩统西垌组下段火山角砾岩中418~469 Ma的年龄不是该火山角砾岩的成岩年龄,该年龄段的锆石可能来自早白垩世砂岩角砾,也可能来自曾被认为是新元古界的变质砂岩角砾。90 Ma的锆石年龄代表了上白垩统西垌组下段火山角砾岩形成之前,深部岩浆喷发活动的年龄,该岩浆活动时限比上段的石英斑岩早约7 Ma。

鲁西归来庄金矿断裂构造控矿规律研究

鲁西地区位于华北克拉通中部,晚中生代受到强烈的克拉通破坏-金成矿作用影响,归来庄金矿是该区内产出最大的低温热液构造-隐爆角砾岩型金矿床。笔者对归来庄金矿主控矿断裂F1的空间变化,从不同标高、不同勘探线统计其走向和倾向上控矿的规律、F1断面产状变化规律、断裂-隐爆角砾岩体中角砾大小和形态的变化规律,对成矿期的构造应力场及其控矿作用展开剖析,查明了成矿期该断裂受左行张剪性应力作用,南部上盘向东下方滑落,北部下盘向西上方移动,具有陡倾面受张开启,缓倾面受压闭合的特点;沿F1断裂的NE上方-SW下方,矿体和蚀变带由浅入深、由陡而缓,角砾粒径逐渐变大,金含量逐渐下降。

安徽淮南舜耕山奥陶系古溶洞发育特征及成因

古溶洞对隐伏地区岩溶地下水储存与运移至关重要,查明其形态及内部结构特征对于认识隐伏煤田岩溶形成过程及矿山岩溶水害防治具有一定的指导意义。近年来,通过对华北板块南缘安徽淮南舜耕山地区奥陶系岩溶野外露头详细的地质勘查,在奥陶系发现1处典型古溶洞。采用野外观测、显微鉴定、古水文和古构造等方法,对古溶洞几何形态特征、内部结构进行系统分析,该溶洞发育于奥陶系古溶洞沿马家沟组和萧县组的沉积层面间,洞体形态宽窄不一,西侧较宽、东侧较窄,最大层间高度达9.8 m,洞体长度为125 m。洞顶面保留古水流冲刷溶蚀痕迹,洞体内存在多处因重力作用垮落坍塌充填物,按其成因,可分为碎屑垮落充填、化学充填以及混合充填等,充填岩屑以灰岩、白云岩类为主,其矿物成分为方解石、白云石、隐晶硅质等。结合区域地质构造演化史,古溶洞形成于加里东运动抬升阶段,经过了裂隙发育、层面岩溶形成、层面间溶洞生长以及崩塌跨落充填压实4个阶段,主要受层面裂隙、侵蚀流体以及岩溶垂向分带控制。研究成果可为淮南煤田乃至华北煤田古岩溶突水防治提供有益参考。

西藏邦铺钼(铜)多金属矿床隐爆角砾岩型矿体的发现及找矿意义

邦铺矿床为冈底斯成矿带东段一个大型斑岩-矽卡岩Mo(Cu)多金属矿床,笔者首次在矿区东部发现了隐爆角砾岩型Pb-Zn-Cu矿体,从而进一步深化完善了邦铺斑岩成矿系统。通过详细的钻孔地质编录和岩相学研究发现,角砾岩筒在垂向上和横向上具有明显的分带性:从浅部到深部,从角砾岩筒中心到边部,依次为爆破相-震碎相-震裂相-裂隙相。角砾岩型Pb-Zn-Cu矿体主要赋存于角砾岩筒的裂隙相和震裂相中,少数赋存于震碎相和爆破相中。方铅矿和闪锌矿呈脉状、网脉状、条带状产于裂隙相的裂隙中和震裂相胶结物中。根据隐爆角砾岩中石英二长斑岩角砾LA-ICP-MS锆石U-Pb年龄((14.51±0.12)Ma)将隐爆角砾岩的形成年龄限定在~14 Ma,该年龄与斑岩矿体成矿年龄((14.67±0.54)Ma~(14.11±0.31)Ma)及矽卡岩矿体成矿年龄((13.93±0.87)Ma)相一致,统一的形成年龄说明隐爆角砾岩应为斑岩成矿系统的一部分。根据斑岩成矿系统中各类型矿体的分布规律,结合冈底期成矿带碰撞造山背景下后碰撞阶段斑岩成矿系统多中心复合成矿的特征,推测邦铺矿区东部很可能还存在另一个同期的斑岩型矿化中心。

Triaxial mechanical properties and precursors of instability damage in rocks with different laminar dip angles

To investigate the mechanical failure characteristics of volcanic breccia with different bedding dip angles in deep layers,triaxial compression experiments were conducted on specimens taken from volcanic rock layers in the Junggar Basin,Xinjiang.By changing the confining pressure,we compared the mechanical properties,acoustic emission characteristics,and fractal features of the acoustic emission sequence for volcanic breccia with different bedding dip angles.The research results indicate that as the bedding dip angle increases,peak strength,internal friction angle,and cohesion exhibit a“U-shaped”variation pattern.The correlation dimension of the acoustic emission amplitude was calculated using the G-P algorithm,revealing that volcanic breccia exhibits fractal characteristics.Furthermore,a positive correlation between the correlation dimension and the bedding dip angle was observed.When the stress of the test specimen reaches 0.8σ_(c),there is a significant decrease in the fractal dimension,serving as a criterion for predicting the failure of the specimen.By analyzing the changes in fractal dimension at different stress levels,the slope of the fractal dimension△D<-0.5 can be used as a precursor to failure for test specimens with a bedding dip angle of 15°≤β≤45°.Similarly,when the bedding dip angle of the specimen is 0°≤β<15°or 45°<β≤90°,△D<0 can be considered as a precursor to specimen failure.This study provides theoretical references for understanding the failure patterns of volcanic rock.

川东五百梯地区石炭系岩溶古地貌识别及储集意义

综合利用钻井、测井、岩心及地震资料,通过建立地震正演模型模拟、RGB分频融合技术及波形分类分析等手段,对川东五百梯地区石炭系岩溶古地貌进行了识别与刻画。研究结果表明:(1)川东五百梯地区石炭系遭受的岩溶作用强度自西向东逐渐变小,东南部石炭系原始沉积厚度更大,但残余厚度分布不均匀,主要为10~30 m;西北部地层厚度较小,为0~15 m。(2)研究区石炭系自西向东可识别出岩溶高地和岩溶斜坡2个二级地貌单元,岩溶斜坡可划分为残丘和浅洼2个三级地貌单元,再依据其差异溶蚀特征,可进一步划分为陡斜坡浅洼和缓斜坡浅洼,浅洼内发育残丘、暗河及落水洞。反射同相轴的上提和下拉特征、岩溶角砾岩的发育、地震层拉平剖面、RGB分频融合及波形变化特征等均可识别出岩溶古地貌的发育。(3)研究区石炭系各地貌单元的分布受构造控制,浅洼和残丘多以椭圆状或不规则长条状呈北西—南东向展布,暗河的展布与浅洼长轴方向一致;岩溶古地貌控制着地层厚度以及溶蚀孔洞的发育,残丘残余厚度较大,岩溶作用强,充填作用较弱,溶蚀孔洞较发育,储层平均孔隙度为4.34%;缓斜坡浅洼残余厚度较小,充填作用较强,溶蚀孔洞不发育,储层平均孔隙度为2.68%,而陡斜坡浅洼虽然残余厚度小,但因潜水位低、泄水能力强,溶蚀作用强而充填作用弱,储集空间发育,储层平均孔隙度为5.05%;缓斜坡和陡斜坡储层平均孔隙度分别为3.67%和3.31%,岩溶高地孔隙度最小,平均为2.51%。

鲁西龙宝山地区隐爆角砾岩特征及稀土成矿意义

兰陵县龙宝山稀土矿是鲁西重要的稀土矿床,其分布受热液流体控制明显,而隐爆角砾岩作为良好的流体通道和容矿空间,为稀土矿勘探的有利目标。通过野外勘查、岩相学观察、扫描电镜以及能谱仪分析,研究隐爆角砾岩筒的结构及其对应的热液蚀变矿化情况,来探讨龙宝山地区隐爆角砾岩的稀土分布规律,结果表明:龙宝山隐爆角砾岩体从内至外大致分为隐爆角砾岩类、隐爆热液岩浆圆化角砾岩类、隐爆震碎角砾岩类以及隐爆破裂岩类多种类型;隐爆角砾岩类、隐爆热液岩浆圆化角砾岩类、隐爆震碎角砾岩类岩石,其分别对应着黄铁绢英岩化、钾长石化绢英岩化以及硅化碳酸盐化;钾化热液富含稀土络合阴离子有助于其迁移,而且黄铁绢英岩化与钾长石化可造成pH和温度的降低等有利于REE沉淀的环境,发生此类蚀变作用的隐爆角砾岩类与隐爆热液浆液圆化角砾岩类是稀土富集的有利场所。

四川德昌县大陆槽稀土矿Ⅰ号矿体地质特征及矿石质量研究

四川冕宁-德昌稀土成矿带是中国最重要的稀土成矿带之一,其中,冕宁牦牛坪稀土矿和德昌大陆槽稀土矿为该成矿带上矿床规模最大的开发矿山。德昌大陆槽稀土矿位于德昌县城221°方向,平距31.6 km的大陆槽乡。区内大面积出露石英闪长岩,其中多期次侵入了正长岩株(脉)。区内查明有Ⅰ号矿体、Ⅲ号矿体,Ⅰ号矿体为正在开发的主矿体,主要赋存于碱性正长岩和方解石碳酸岩内,呈扁柱状,大型规模。矿石主要为半自形细-中粒结构、碎裂结构,角砾状构造、浸染状构造。有益组分主要为铈和镧,呈氟碳铈矿相产出,伴生有Sr、Ba、F、Pb,有害组分ThO2和U含量微少。REO矿床平均含量3.64%。矿区水文地质条件、工程地质条件、地质环境质量中等。该矿床属隐爆角砾岩型稀土矿床。

水利枢纽工程溶塌角砾岩隧洞涌水塌方施工技术

对溶塌性角砾岩特性地貌岩溶发育特点进行综合分析后发现,使用普通的处理方法很难实现对塌方体的高效处理,因此,出台了自进式管棚处理办法,使塌方体得以高效处理。论文针对水利枢纽工程溶塌性角砾岩隧洞涌水塌方的初期支护和施工工序等情况开展了全面而透彻的分析,实现了人们从涌水塌方段的安全通过。

Geology, Geochemistry and Origin of the Hongshan Porphyry-Cryptoexplosive Breccia Type Copper Deposit in Huichang County, Jiangxi Prvince

The Hongshan porphyry-cryptoexplosive breccia type copper deposit occurs in a metamorphic rock series of the Mesoproterozoic Zhongcun Group. Orebodies are distributed inside and outside porphyry-cryptoexplosive breccia pipes. The deposit involves five ore-forming types, i.e the porphyry type, cryptoexplosive breccia type, contact-zone veinlet-disseminated type, in-pipe fracture-zone filling-replacement type and out-of-pipe fracture-zone filling-replacement type, forming an ore-forming system of “five ore-forming types within a single rock body”. Fluid inclusion and isotope geochemical studies indicate the following: S, Pb, O and Sr were derived from the lower crust, Nd was derived from the continental crust or depleted mantle and rare earth elements (REE) and trace elements have the crustal source characters; fluids consist dominantly of formation water, metamorphic water and ***meteoric water with a part of magmatic mater, heat came from porphyry while the latter originated from partial melting caused by shear heating in the lower crust and upper mantle. According to its origin the deposit is classified as the hypabyssal and near-surface, meso- and hypothermal copper deposit associated with the late Yanshanian porphyry-cryptoexplosive breccia.

Fluidization: An Important Process in the Formation of the Qiyugou Au-bearing Breccia Pipes in Central China

Fluidization processes based on experiments are reviewed to gain some useful insights and comparisons with those that occur in hydrothermal systems. Field and petrographic work, and microscope observation were carried out on samples from the Qiyugou Au-bearing breccia pipes from the East Qinling region, Henan Province. Evidence from macro- and micro-textures suggests that the style of breccias in the Qiyugou area can be grouped into three types： （1） jigsaw fit-stockwork texture, in which the interval between clasts is marked by fractures or filled with calcite or quartz veins; （2） larger breccias that are supported by smaller breccias, rock flour and alteration materials; in this type clasts moved over short distances, creating open spaces; （3） fluidized texture, where the clasts of different lithologies have rounded shapes. These observations are compared with those resulting from experiments on fluidization processes. The results of this comparison suggest that fluidization is an important geological process in the formation of the Qiyugou Au-bearing breccia pipes and gold mineralization. In addition, fluidization processes such as expansion, bubbling, slugging, channeling and spouting must have contributed to the formation of the pipes and were conducive to the development of gold mineralization. In the Qiyugou breccia pipes, gold mineralization occurs as disseminations, in stockwork veins, and open space infills. The ore zones form subparallel sheets that are nearly perpendicular to the walls of the pipes.