新疆哈密三岔口石英闪长岩体中发现锌铜矿

锌铜矿是自然界较为少见的含金矿物,以往均发现于基性——超基性岩中,在中酸性岩中发现锌铜矿,在新疆尚属首次.     

塔克拉玛干沙漠石英氧同位素与粒级关系的研究

沙漠与黄土的物源联系是黄土研究关注的问题之一。石英氧同位素可示踪物源,粒度被用以分析沉积环境,但在沙漠物源研究中将二者结合应用的报道尚不多。本文测定了塔克拉玛干沙漠沙丘沙和沙丘剖面中河湖相沉积物的粒度及不同粒级的石英氧同位素,结果显示:1沙丘沙以极细砂和细砂为主,粉砂和黏土含量很低;河湖相沉积物以粉砂和黏土为主,砂含量低于5%。2各粒级石英δ~(18)OSMOW值介于13.8‰~19.7‰,其中沙丘沙为13.8‰~19.7‰,河湖相沉积物为15.6‰~17.6‰;沙丘沙石英δ~(18)O值随粒级增大未呈现减小趋势,同一粒级石英的δ~(18)O值存在一定变异。3经比较,塔克拉玛干沙漠砂和粉砂粒级的石英δ~(18)O值均高于中国其他沙漠,且20μm的石英δ~(18)O值与黄土高原的马兰黄土、洛川黄土—古土壤序列20μm的石英δ~(18)O值并无显著性差异。     

陕西石泉北部羊坪湾金矿石英脉流体包裹体特征研究

羊坪湾金矿为陕西石泉-汉阴-旬阳金矿整装勘查区东部的一个重要的金矿,前人曾在该地区开展过大量勘探和综合研究,并取得一定的认识成果（李会民等,1997;李福让等,2009;任小华等,2015）。本次研究通过采集羊坪湾金矿中S2和S3不同期次的石英脉,对其进行流体包裹体测温研究,分析总结不同期次的石英脉包裹体特征,并对探讨其同金矿之间的关系。     

北部湾北部沉积物中石英砂表面的微结构

本文利用扫描电镜,观察了调查区现代石英砂表面的微结构。研究结果表明,在亚热带海域中的石英颗粒表面化学溶蚀痕迹最为发育。     

Integrated methodology for determining provenance of detrital quartz using optical petrographic microscopy and cathodoluminescence (CL) properties

The provenance of detrital quartz is a useful predictor in frontier basin sandstone reservoirs of the availability of coarse-grained quartz grains of plutonic or high grade metamorphic origin. The standard approach is to use scanning electron microscope (SEM) panchromatic cathodoluminescence (CL) imagery and observations from an optical petrographic microscope. We describe a work flow, modified from previous literature proposals, to determine quartz provenance in detrital grains using optical petrographic microscopy and CL properties from both a hot-cathode cathodoluminescence microscope attachment (HCMA) and panchromatic SEM-CL. HCMA analysis permits better discrimination of different types of metamorphic quartz. This method is applied to a Middle Jurassic to Lower Cretaceous section in the Bandol-1 wildcat well, located in the Laurentian sub-basin south of Newfoundland. Two types of high-grade metamorphic quartz are distinguished, one with low luminescence as described in previous literature and one with medium blue CL colour and a moderate colour shift that is also known from granulite in the hinterland. Three phases of detrital supply are identified, suggesting progressive unroofing of higher grade metamorphic sources through the middle Jurassic and major input of plutonic quartz in the early Cretaceous.     

New insights into a late-Pleistocene human occupation in America: The Vale da Pedra Furada complete chronological study

Within the framework of the studies focusing on the Pleistocene peopling of the Americas, our French-Brazilian team has undertaken a pluridisciplinary research on different archaeological sites, inside and in the neighborhood of the Serra da Capivara National Park, in Brazilian Nordeste. The present study regards an archaeological site, Vale da Pedra Furada, situated in the Piauí state in Brazil. The results of technological and functional studies suggest the existence of different successive human occupations during the Pleistocene in this region. Moreover, the geological and geomorphological studies shed new light on our understanding of sedimentary processes and confirm that the levels were not subject to any significant post-depositional processes. This is also confirmed by macro- and micro-analysis of quartz artefact surfaces. The chronological study has recently been completed employing both radiocarbon and luminescence techniques; radiocarbon dates were obtained on charcoal, multi-grain and single-grain OSL ages on sedimentary quartz grains. The results obtained with the different methods are consistent with each other: the most recent archaeological level is dated to around 8 ka and the oldest to 24 ka, indicating the open-air site of Vale da Pedra Furada to be a succession of human occupations beginning from OIS 2. These results are discussed in the context of some archaeological sites studied in the Serra da Capivara National Park of the last few decades.     

Fluid behaviors from the seismogenic region of Longmenshan fault zone,eastern Tibetan PlateauSCIEI北大核心CSCD

震间期、同震期和震后期流体对断裂带物质的强度和运动性质起到重要作用。前人已识别出断裂带浅部区域流体对断层的弱化以及矿物沉淀导致的断层愈合,然而对于断裂带深部流体的研究鲜有报道。为深入了解孕震区流体行为以及地震成核过程中流体对断层的影响,本文以龙门山断裂带的映秀-北川断裂南段虹口乡八角庙村附近碎裂岩滑动带中石英和方解石脉为研究对象,通过对断裂带脉体的显微构造、碳氧同位素和主量元素含量等分析,开展地震相关脉体的特征结构、流体来源和矿物沉淀环境的研究。结果表明,碎裂岩主滑移带由颜色结构不同的三层断层泥和细小的方解石条带组成,在主滑动带边部和上盘碎裂岩中则分别发育了指示震间期、同震期和震后期三个阶段断层活动的脉体:(1)沿阶步生长的纤维状方解石脉和拉伸型柱状颗粒方解石脉;(2)断层泥楔入脉;(3)近等粒状方解石脉以及具有横向竞争生长结构的非等粒状方解石脉和石英脉。它们分别代表了震间期封闭的还原环境下的微滑动、同震外源高压流体注入以及震后开放的氧化环境至还原环境下的矿物沉淀。碳氧同位素结果表明主滑动带和碎裂岩方解石脉δ^(18)O V-PDB值为-20.5‰~-20.3‰,低于围岩碳酸钙胶结物,表明方解石脉具有大气水来源特征。方解石沉淀温度结合地温梯度表明方解石脉的形成深度大于4km,与碎裂岩形成深度及龙门山断裂带震源深度一致。该地区方解石脉和石英脉的研究深化了关于龙门山断裂带孕震区流体行为的理解,并且对进一步认识震间期、同震期和震后期断层的强度变化机制具有重要意义。     

Development of crystallographic preferred orientations by nucleation and growth of new grains in experimentally deformed quartz single crystals

Deformation experiments have been carried out to investigate the effect of dynamic recrystallisation on crystallographic preferred orientation (CPO) development. Cylindrical samples of natural single crystals of quartz were axially deformed together with 1 vol.% of added water and 20 mg of Mn₂O₃ powder in a Griggs solid medium deformation apparatus in different crystallographic orientations with compression direction: (i) parallel to <c>, (ii) at 45° to <c> and 45° to <a> and (iii) parallel to <a>. The experiments were performed at a temperature of 800 °C, a confining pressure of 1.2 GPa, a strain rate of  10^− 6 s^− 1, to bulk finite strains of  14–36%. The deformed samples were analysed in detail using optical microscopy, electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). Two different microstructural domains were distinguished in the deformed samples: (i) domains with undulatory extinction and deformation lamellae, and (ii) domains with new recrystallised grains. Within the domains of undulatory extinction, crystal-plastic deformation caused gradual rotations of the crystal lattice up to  30° away from the host orientation. New recrystallised grains show a strong CPO with c-axis maxima at  45° to the compression direction. This is the case in all experiments, irrespective of the initial crystallographic orientation. The results show that c-axes are not continuously rotated towards the new maxima. The new grains thus developed through a mechanism different from subgrain rotation recrystallisation. New grains have a subeuhedral shape and numerous microcavities, voids, fluid channels and fluid inclusions at their grain boundaries. No host control is recorded in misorientation axes across their large angle grain boundaries. New grains might have been created by nucleation from solution in the μm-scale voids and microfractures. The CPO most likely developed due to preferred growth of the freshly precipitated grains with orientations suitable for intracrystalline deformation at the imposed experimental conditions.     

Fluid inclusion characteristics of hematite-bearing quartz vein from the Daenam mine, Republic of Korea

The Daenam mine, which produced over 9250 tons of iron oxide ore from 1958 to 1962, is situated in the Early Cretaceous Yeongyang subbasin of the Gyeongsang basin. It consists of two lens-shaped, hematite-bearing quartz veins that occur along faults in Cretaceous leucocratic granite. The hematite-bearing quartz veins are mainly composed of massive and euhedral quartz and hematite with minor amounts of pyrite, pyrrhotite, mica, feldspar and chlorite.Fluid inclusions in quartz can be divided into three main types: CO₂-rich, CO₂–H₂O, and H₂O-rich. Hydrothermal fluids related to the formation of hematite are composed of either H₂O–CO₂–NaCl ± CH₄ (homogenization temperature: 262–455 °C, salinity <7 eq. wt.% NaCl) or H₂O–NaCl (homogenization temperature: 182–266 °C, and salinity <5.1 eq. wt.% NaCl), both of which evolved by mixing with deeply circulating meteoric water. Hematite from the quartz veins in the Daenam mine was mainly deposited by unmixing of H₂O–CO₂–NaCl ± CH₄ fluids with loss of the CO₂ + CH₄ vapor phase and mixing with downward percolating meteoric water providing oxidizing conditions.     

东濮凹陷桥口-白庙地区砂岩石英增生及其对流体活动的反映

对东濮凹陷下第三系储层砂岩石英增生边及其中的流体包裹体进行了鉴定和检测,结果表明东濮凹陷桥口-白庙地区共有3期石英增生现象,代表3期流体活动。第1期与第2期发生在盆地深陷期,当时埋深1700～3000m,年代28～37Ma,第3期增生边尚不能确定其形成条件,但可确定其形成于碳酸盐大规模交代石英颗粒之后。桥口地区第1期所代表的流体活动温度主要在110～115℃,第2期所代表的流体活动温度主要在130～135℃。白庙地区第1期所代表的流体活动温度主要在105～110℃,第2期所代表的流体活动温度主要在120～125℃。这3期流体活动的性质可能是粘土矿物转化过程中释放的晶格水通过泥岩的幕式压裂作用向砂岩中释放的结果。