新疆阿尔泰可可托海伟晶岩型稀有金属矿床中磷灰石地球化学特征及意义     

白应雄  申萍  曹冲  潘鸿迪  李昌昊  罗耀清  冯浩轩  索青宇 《岩石学报》2021,37(9):2843-2860

磷灰石可以记录和保存岩浆和热液活动的信息。可可托海伟晶岩型稀有金属矿床磷灰石发育,为研究该矿床伟晶岩成岩成矿过程提供了优良的条件。已有对可可托海伟晶岩型稀有金属矿床磷灰石的研究集中在其稀土元素特征,较少讨论其对伟晶岩成岩成矿过程的制约。本文选取可可托海伟晶岩型稀有金属矿床富矿伟晶岩脉(3号脉)和相对贫矿伟晶岩脉(1号、2b号和3a号脉)中的磷灰石作为研究对象,进行磷灰石岩相学和地球化学研究。岩相学分析表明,磷灰石主要与钠长石、石英、白云母、锰铝榴石等伴生。EPMA分析显示,磷灰石F含量为3.67%～4.41%,Cl含量小于0.67%,较低的Cl含量表明伟晶岩熔体出溶的流体Cl含量较低;大部分磷灰石MnO含量为4.67%～8.71%,但2b号脉磷灰石MnO含量变化较大(1.23%～14.28%),这是由于2b号脉磷灰石具有分带结构,暗示其遭受后期热液作用,促使磷灰石溶解-再沉淀,导致MnO含量发生较大变化。LA-ICP-MS分析显示,贫矿伟晶岩脉磷灰石的稀土元素含量较低(180×10~(-6));相反,富矿伟晶岩脉磷灰石的稀土元素含量较高( 700×10~(-6)),并具有明显的四分组效应(TE_(1-3)平均值为1.7)。1号脉和3a号脉磷灰石均显示轻稀土元素富集,反映其形成过程中有含Cl热液的参与。3号脉磷灰石显示强烈Eu负异常和Ce正异常,而2b号脉磷灰石显示强烈Ce负异常和中等Eu负异常,这种Eu、Ce异常的差异可能与岩浆-热液阶段大量流体出溶密切相关。磷灰石的沉淀将导致热液中HF含量的降低,促使磷灰石周围铌钽矿结晶和Nb、Ta进入磷灰石中。可见,在伟晶岩形成过程中,磷灰石并非保持稳定,其分带结构和主微量成分变化记录了后期热液活动,暗示后期热液活动对伟晶岩的成矿具有重要作用。  相似文献   

金川铜镍硫化物矿床中铂族矿物的主要类型和产出特征:热液蚀变过程中铂族元素的富集机理     

董宇  魏博  王焰 《岩石学报》2021,37(9):2875-2888

金川铜镍硫化物矿床是我国最主要的铂族元素(PGE)资源产地,其矿石受热液蚀变作用影响明显,并产出多种铂族矿物(PGM)。岩浆演化和热液蚀变过程中PGE的迁移富集机制和PGM的成因,一直是研究PGE地球化学行为非常关注的问题。本文对金川铜镍硫化物矿床中PGM的研究发现,其主要类型包括含PGE的硫砷化物(硫砷铱矿)和砷化物(砷铂矿),Pd的铋化物、碲化物和硒化物,以及少量其他铂族矿物。其中,硫砷铱矿可包裹于各种贱金属硫化物(镍黄铁矿、磁黄铁矿和黄铜矿)中,表明硫砷铱矿可能结晶于早期的含As硫化物熔体,随后被包裹于硫化物熔体冷凝分异产生的单硫化物固溶体(MSS)和中间硫化物固溶体(ISS)中。硫化物熔体中的As可能主要通过地壳混染作用加入幔源岩浆。大量铋钯矿(PdBi)呈微细乳滴状包裹于黄铜矿中,为晚期ISS冷凝形成黄铜矿过程中出溶的产物。少量铋钯矿(PdBi_2)呈不规则状充填于矿物裂隙,与次生磁铁矿脉紧密共生,并随矿石的蚀变程度增加,铋钯矿的化学成分由PdBi逐渐向PdBi_2转变,表明这部分铋钯矿为后期热液蚀变产物。铋碲钯矿和钯的硒化物则主要产出于镍黄铁矿裂隙且与次生磁铁矿紧密共生,指示明显的热液成因。钯的硒化物的出现表明,岩浆期后酸性、高盐度、高氧逸度的富Cl~-流体对金川铜镍硫化物矿床中Pd的迁移和富集起到了关键控制作用。  相似文献   

内蒙古黄岗梁铁锡矿床中红色萤石的地球化学特征及成因探讨     

陈缘  韩禹  许博  刘金高 《岩石学报》2021,37(12):3869-3879

内蒙古黄岗梁萤石呈现稀有的红色特征,该颜色萤石全球产量稀少,本文利用LA-ICP-MS原位测试技术对其微量元素地球化学特征进行了系统分析,探讨黄岗梁铁锡矿床中红色萤石的成因。微量元素分析结果显示黄岗梁萤石样品中总稀土元素含量较低,并表现出左倾的富集重稀土特征,其中红色和粉色萤石的稀土元素配分曲线显示出Dy-Tm拱顶式凸起的配分模式,表明其结晶作用发生在成矿流体演化的最后阶段;Y/Ho比值104~197,与热液成因萤石一致,且La/Ho比值为0.027~0.126,具强的负异常,表明了黄岗梁萤石为热液成因;Ce/Ce^*比值0.57~0.98,Eu/Eu^*比值0.22~0.63,均表现出负异常,表明形成黄岗梁萤石的热液流体是在相对还原环境下形成且温度高于200℃。综合分析萤石的地球化学特征和其与围岩的接触关系,认为黄岗梁萤石主要分为两阶段结晶,一阶段为与石英同期结晶形成红色、粉色部分,二阶段为在石英形成后结晶形成的由阳起石他色致色的绿色部分,而黄岗梁萤石罕见的红色是由于Y元素较为富集且含量远高于其他稀土元素,从而形成YO₂色心并在萤石中作用而显色。  相似文献   

Hydrothermal alteration processes in the giant Dahutang tungsten deposit,South China: Implications from litho-geochemistry and mass balance calculation     

Hai-Bo Zhao  Yong Zhang  Lei Liu 《China Geology》2021,4(2):230-244

The giant Dahutang tungsten (W) deposit has a total reserve of more than 1.31 Mt WO₃. Veinlet-disseminated scheelite and vein type wolframite mineralization are developed in this deposit, which are related to Late Mesozoic biotite granite. Four major types of alterations, which include albitization, potassic-alteration, and greisenization, and overprinted silicification developed in contact zone. The mass balance calculate of the four alteration types were used to further understanding of the mineralization process. The fresh porphyritic biotite granite has high Nb, Ta, and W, but low Ca and Sr while the Jiuling granodiorite has high Ca and Sr, but low Nb, Ta, and W concentrations. The altered porphyritic biotite granite indicated that the Nb, Ta, and W were leached out from the fresh porphyritic biotite granite, especially by sodic alteration. The low Ca and Sr contents of the altered Neoproterozoic Jiuling granodiorite indicate that Ca and Sr had been leached out from the fresh granodiorite by the fluid from Mesozoic porphyritic biotite granites. The metal W of the Dahutang deposit was mainly derived from the fluid exsolution from the melt and alteration of W-bearing granites. This study of alteration presents a new hydrothermal circulation model to understand tungsten mineralization in the Dahutang deposit.  相似文献   

热液金刚石压腔(HDAC)高温高压实验平台简介          下载免费PDF全文

李胜虎  熊玉新  单伟  舒磊  迟乃杰 《山东国土资源》2021,37(1):50-52

热液金刚石压腔(HDAC)高温高压实验平台是在金刚石压腔的基础上发展起来的一种高温高压原位实验模拟设备.近年来,HDAC技术已经在地质科研领域取得了大量成果,多篇重要研究成果被《Science》《Nature》等知名期刊刊发.本文介绍了HDAC高温高压实验平台结构与组成、实验优势和应用前景.  相似文献   

云南香格里拉市热林铅锌银矿特征及找矿标志     

赵贤  孙涛  胡成军 《云南地质》2021,(1):42-46

云南香格里拉市热林铅锌银矿,矿体呈似层状赋存于三叠系上统曲嘎寺组三段(T3q3)之大理岩与板岩的层间构造破碎带中,矿体明显受断层构造及特定的岩性控制.该矿床属断层破碎带控制的热液型铅锌银矿床,断层破碎带和地球化学异常是直接的找矿标志,沿断层带出现的硅化、碳酸盐化、黄铁矿化和角岩化是间接的找矿标志.  相似文献   

基于 MODIS 数据的吐鲁番盆地 2001—2017 年 植被变化及水热组合影响分析          下载免费PDF全文

庞冉  王文 《干旱区地理》2020,43(5):1242-1252

中国西北干旱地区的气候变化及其对植被的影响一直备受关注。以地形特殊的吐鲁番盆 地为研究对象,利用实测气象站点数据、再分析气象格点数据以及 MODIS 卫星遥感植被指数,采用 趋势检验、线性回归、偏相关分析等方法,探究了该地区 2001—2017 年间的植被变化及其与水热组 合特征之间的关系。结果表明：（1）吐鲁番盆地降水量整体没有显著变化,但北部山区降水增长较 多,气温总体呈显著上升趋势,尤其是盆地底部中心区域增温较大。（2）全区域植被指数（NDVI）总 体呈极显著上升趋势,山区及中心区域 NDVI 增长率较大。（3）受水汽来源和日照时长的影响,吐鲁 番盆地周边山区高程 3 000 m 左右 NDVI 值最高,山区植被最好的坡向是西北坡。（4）吐鲁番盆地水 热组合复杂,水分条件是大部分地区植被生长的主要限制因素,降水与 NDVI 有较好的正相关,在 山区和荒漠区热量增加不利于植被生长,但中心区域受地下水和人类活动影响,水分的供给相对 稳定,热量增加利于植被生长。  相似文献   

Distribution and spatial variation of hydrothermal faunal assemblages at Lucky Strike (Mid-Atlantic Ridge) revealed by high-resolution video image analysis     

Daphne Cuvelier  Joze Sarrazin  Ana Colao  Jon Copley  Daniel Desbruyres  Adrian G. Glover  Paul Tyler  Ricardo Serro Santos 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(11):2026-2040

Whilst the fauna inhabiting hydrothermal vent structures in the Atlantic Ocean is reasonably well known, less is understood about the spatial distributions of the fauna in relation to abiotic and biotic factors. In this study, a major active hydrothermal edifice (Eiffel Tower, at 1690 m depth) on the Lucky Strike vent field (Mid-Atlantic Ridge (MAR)) was investigated. Video transects were carried out by ROV Victor 6000 and complete image coverage was acquired. Four distinct assemblages, ranging from dense larger-sized Bathymodiolus mussel beds to smaller-sized mussel clumps and alvinocaridid shrimps, and two types of substrata were defined based on high definition photographs and video imagery. To evaluate spatial variation, faunal distribution was mapped in three dimensions. A high degree of patchiness characterizes this 11 m high sulfide structure. The differences observed in assemblage and substratum distribution were related to habitat characteristics (fluid exits, depth and structure orientation). Gradients in community structure were observed, which coincided with an increasing distance from the fluid exits. A biological zonation model for the Eiffel Tower edifice was created in which faunal composition and distribution can be visually explained by the presence/absence of fluid exits.  相似文献   

热液条件下CO2和H2反应产烃研究进展     

季福武  周怀阳  杨群慧 《地球科学进展》2007,22(1):41-48

热液条件下CO2和H2形成烷烃的反应,提供了自然条件下CO2转化为有机质的一条非生物途径。研究这一过程,对于油气费托非生物成因研究和海底热液生命起源的讨论具有重要意义。已有研究表明,热力学有利的温度、压强条件和合适的催化剂,是热液条件下CO2和H2发生反应形成烷烃的必需条件。在热力学有利的条件下,铬铁矿能够催化反应形成CH4、C2H6和C3H8,但还不清楚是否存在能够促使反应产生C4H10等长链烷烃的天然矿物催化剂。含一种或多种过渡金属元素的磁铁矿,可能是值得考察的对象。另外,研究热液条件下CO2和H2反应形成烷烃的过程和机理,建立反应所形成烷烃的C、H同位素综合判识指标,是今后值得探索的研究课题。  相似文献   

Structurally controlled hydrothermal dolomites in Albian carbonates of the Asón valley,Basque Cantabrian Basin,Northern Spain     

M.A. López-Horgue  E. Iriarte  S. Schröder  P.A. Fernández-Mendiola  B. Caline  H. Corneyllie  J. Frémont  M. Sudrie  S. Zerti 《Marine and Petroleum Geology》2010

Shallow marine carbonate sedimentation dominated during the Albian in the western part of the Basque Cantabrian Basin in Northern Spain, forming the large Ramales Platform. This platform originated on a less subsiding tectonic block facing deeper and more subsiding areas to the south and east, which were created by tectonic activity in the Basin. Fracture-related hydrothermal dolomites hosted in these Albian carbonates are well exposed in the Asón valley area. Mapping in the studied area revealed several dolomite bodies related to main faults that cut the stratification almost at right angles. The bodies show a vertical development along fault-strike up to 900 m thick from which kilometre-scale branches expand following the stratification. Dolomitization is pervasive and independent of the limestone facies. Main dolomite facies are fine replacive, sucrosic and saddle. Petrography, C, O and Sr isotopes and fluid-inclusion analysis support a polyphase hydrothermal dolomitization at fluid temperatures between 75 °C and 240 °C and highly variable salinity of up to 22 wt.% NaCl. Fine dolomite replaced limestone first and then, sucrosic and saddle dolomites replaced part of the first dolomite and cemented newly created fracture porosity together with different calcite cements. Zebra dolomites and hydroclastic breccias are products of this later stage. Burial analysis of the host rock supports maximum burial temperatures of 80 °C and intense tectonic activity from the Albian to Turonian with a latest Albian peak subsidence. Albian stretching of the crust and subsequent ascent of the isotherms in the area is suggested to have produced sufficient heat to the dolomitizing fluids. The structural analysis indicates a strong transtensional tectonic activity in the studied area during Albian to Turonian time with the creation of an overstep between W–E trending and N–S trending faults. Fluids moved from subsiding areas to fractured uplifted parts of the Ramales Platform, enhanced by diapiric activity.  相似文献