胶东金矿成矿模式   总被引：14，自引：4，他引：10  

宋明春  林少一  杨立强  宋英昕  丁正江  李杰  李世勇  周明岭 《矿床地质》2020,39(2):215-236

胶东是全球三大金矿集区之一,深入研究其成矿模式对于正确认识胶东金矿类型并指导进一步找矿具有重要的理论意义和实践价值。文章通过系统总结胶东金矿控矿构造特征与型式、构造与矿体的耦合关系、岩浆活动与金矿化的关系及其他成矿地质因素,在分析不同类型和不同层次金矿赋矿规律、成矿机制的基础上,分别建立了破碎带蚀变岩型金矿、石英脉型金矿、胶西北金矿和深部金矿成矿模式。综合分析后,提出了胶东金矿热隆-伸展成矿模式,其要义是:早白垩世,由于板块俯冲、回撤,诱发壳幔相互作用,产生大规模岩浆活动,引起广泛的流体活动;同时,地壳拉张和岩浆隆升,形成花岗岩穹窿-伸展构造,出现大量铲式断层、拆离断层等。与岩浆活动有关的高强度含矿流体活动和交代蚀变作用是胶东金矿大规模集中产出的基础条件,地壳快速隆升引起强烈减压、降温是大量金质从流体中析出、沉淀的重要原因,伸展构造则为大规模金成矿提供了充足的空间。  相似文献   

基于二维连续小波变换的颗粒物数字粒径方法研究     

郭立恒  刘海江 《海洋工程》2018,36(5):38-48

对于海岸工程的研究而言,测定泥沙、砾石、卵石等颗粒物的中值粒径具有重要的研究意义。近年来,许多学者逐渐将统计学方法应用于分析泥沙等颗粒物的粒径大小及其级配分布,小波变换是该研究领域时新的统计计算数学方法之一。由于一维连续小波变换(1D-CWT)在估算颗粒数值粒径方面存在一定的局限性,本研究基于二维连续小波变换(2D-CWT),提出了新的颗粒物粒径统计学分析方法,用于估算筛分良好的颗粒物中值粒径。以玻璃珠、卵石块和砾石三类不同性质的颗粒物构建数字粒径实验分析样本,对新方法进行了测试和验证。研究表明基于2D-CWT的数字粒径分析方法能够快速、便捷地估算出筛分良好的颗粒物的中值粒径,且计算结果准确、稳定。相较于基于1D-CWT的数字粒径分析方法,2D-CWT方法在颗粒物数字粒径分析方面有着更高的计算成功率和更广的适用性。  相似文献   

Stratiform and stratabound tungsten mineralisation in the Broken Hill Block,N.S.W.     

Robert G. Barnes 《Australian Journal of Earth Sciences》2013,60(1-2):225-239

The Early‐Middle Proterozoic Broken Hill Block contains three types of W occurrences, which show close stratigraphic control. All three types occur within a relatively narrow stratigraphic interval (the ‘Mine Sequence’ Suite of Stevens et al., 1980) comprising a highly variable group of metamorphosed silicic and mafic volcanics, clastic sediments, and exhalative and chemical sediments containing base metals. The first type includes occurrences of W and base metals in bedded calc‐silicate rocks. In the second type, W occurs in layered to non‐layered calcsilicate rocks associated with amphibolite; these are intimately associated in a narrow stratigraphic interval containing abundant, small, Broken Hill type deposits. The third type comprises stratabound, W‐bearing pegmatites, which have been remobilised from quartz‐feldspar‐biotite gneiss and bedded quartz‐tourmaline rocks. Tungsten has been mined only from the third type and only in small quantities. The three types of tungsten deposits show a close spatial relationship with stratiform and stratabound Pb‐Zn mineralisation, including the Broken Hill type. The Pb‐Zn and W deposits are inferred to be genetically related.  相似文献   

桂东北地区鹰扬关韧性剪切带的厘定及其构造意义     

秦亚  冯佐海  吴杰  薛云峰  胡乔帆  白玉明  周鹏程 《地球学报》2023,44(3):434-454

论文通过宏-微观构造、磁组构、热液锆石和石英EBSD组构等,厘定鹰扬关韧性剪切带并讨论其构造意义。鹰扬关韧性剪切带具有宏-微观韧性变形组构,发育糜棱岩、拉伸线理、S-C组构、旋转碎斑系、书斜构造、压力影和石英的动态重结晶等。磁组构和宏-微观构造表明,鹰扬关韧性剪切带呈NNE向延伸超过40 km,宽2.5～8 km。糜棱C面理的极密点产状127°∠50°;磁面理的极密点产状107°∠83°。宏-微观构造研究表明,鹰扬关韧性剪切带具有早期左旋逆冲剪切,晚期右旋正滑剪切的运动学性质。石英EBSD组构表明,鹰扬关韧性剪切带具有晚期中低温变形(400～550℃)叠加于早期中高温变形(550～650℃)的特征。年代学研究表明,鹰扬关韧性剪切带早期左旋逆冲剪切的时代为(441.1±2.3)Ma,晚期右旋正滑剪切的时代应晚于420 Ma,区域构造应力由挤压转为伸展的时限为420 Ma。在磁组构、石英EBSD组构和热液锆石定年的基础上,结合区域地质资料,认为鹰扬关韧性剪切带形成于华夏陆块自SE向扬子陆块造山挤压的构造背景。早期造山挤压,产生压扁型应变和中高温左旋逆冲剪切;晚期造山后伸展,产生拉伸型应变和...  相似文献   

山地冰川冰消后（paraglacial）沉积的粒度与石英颗粒表面特征——以贡嘎山东坡为例     

王杰  雷满红  郑利敏 《冰川冻土》2022,44(4):1150-1164

冰期向间冰期转换或现代全球气候变暖等背景下,冰川一旦退缩就会引发基岩和冰碛边坡失稳,甚至冰川泥石流等冰消后（paraglacial）地表过程;因此,该过程成为驱动原冰川作用区及其下游谷地地貌演化的重要因子。然而,冰消后过程时空变化特征及其驱动因子等相关研究,目前仍面临两方面问题：其一,各种冰消后沉积、冰碛等混杂堆积间判别的手段缺乏;其二,冰消后过程对下游谷地演化影响的关注不足。为此,本文以典型海洋型冰川作用区——贡嘎山东坡的冰碛和冰消后沉积为研究对象,并结合两处大陆型冰川冰碛,探讨了粒度和石英颗粒表面形态特征两个指标区分上述混杂堆积的有效性。结果表明,各种冰消后沉积物继承了源区冰碛的很多特征,但也呈现出一定独特性,指示出这两个指标综合对比的方法能实现各类冰消后沉积、冰碛的有效判别;同时,鉴于冰川性质、冰川作用期次和岩性等因素都可能影响源区冰碛的粒度和石英颗粒表面形态,以这两个指标判别时应限于同区域,避免选用沉积物的共性特征。基于贡嘎山东坡冰碛、各种冰消后沉积物与磨西台地不同层位粒度与石英颗粒表面形态的对比和聚类分析,确认台地底部和中部可能分别为MIS3冰碛与MIS3以来的泥石流沉积,上部则可能为河流沉积或河流改造过的冰川泥石流沉积。磨西谷地冰消后过程堆积和暴露时代,指示出强烈冰消后过程使得磨西河谷地末次冰期向全新世转换时一直在堆积,甚至持续到约6~7 ka前后才停止,之后转为侵蚀下切。  相似文献   

Violet stimulated luminescence as an alternative for dating complex colluvial sediments in the Atacama Desert     

《Quaternary Geochronology》2022

Luminescence dating has become a key tool in studies of the Quaternary. The typically stable luminescence response of quartz grains and the absence of a significant internal dose, make quartz minerals the preferred dosimeter for monitoring the burial dose in sediments. Unfortunately, the reliability of conventional OSL (optically stimulated luminescence) dating, based on blue stimulation, can be compromised when the luminescence decay is not dominated by a rapidly decaying and stable part of the luminescence signal (i.e. the fast component). On the other hand, standard methods in luminescence dating are limited to ages of a few hundred kiloyears. In this study, violet stimulated luminescence (VSL) has been used as a means to overcome both problems, applied to a series of colluvial deposits in the Atacama Desert, Chile. Quartz from this region, characterized by poor blue-OSL response, showed a reproducible and stable VSL signal capable of recovering given doses up to ∼500 Gy and a saturation dose twice as high as conventional OSL. The VSL response from these samples has been studied in detail and the estimated ages have been compared with an already established chronology for the same site, based on IRSL of potassium feldspar single grains. Results agree for the dose range of the profile studied, ∼100–250 Gy, equivalent to ages of 29–79 ka confirming the suitability of VSL for dating sedimentary quartz with unreliable blue-OSL response and to extend the age range of conventional OSL dating.  相似文献   

石英包体拉曼偏移压力计——一种变质压力计算方法     

王美慧  张立飞 《岩石矿物学杂志》2023,42(1):113-120

矿物或流体包体可以有效保存寄主矿物生长过程中的化学环境、温度、压力等信息。在高压变质过程中,石榴子石中石英包体的分子振动与环境压力之间具有良好的相关性。根据这一特性,前人提出了石英包体拉曼偏移压力计,其原理是利用显微激光拉曼光谱仪分析石英包体在室温常压下保留的残余压力,再结合石英与寄主矿物的弹性物理特性,恢复石英包体被捕获时的压力,属于矿物物理光谱学压力计,本文介绍了利用石英包体的拉曼位移计算变质压力的基本原理和方法,并对不同方法的适用条件和使用局限做了简要分析。石英包体拉曼偏移压力计是恢复变质岩石形成温度和压力条件的有效方法,具有广泛的应用前景。  相似文献   

湖南省醴陵李畋—王仙地区石炭系岩相特征及其石英砂岩资源潜力分析     

文亭  刘守林  汤贺军  李燕普  刘鹤群  王淑军  刘一帆 《地球学报》2023,44(6):955-966

湖南省石炭系地层蕴藏着丰富的石英砂资源, 对该地层序列的研究不仅有助于深入分析石英砂形成的古地理环境特征, 而且结合构造背景的研究, 可总结石英砂成因及分布规律, 为我省硅产业发展所需原料的开发提供理论依据。为此, 本文以李畋—王仙地区石炭系地层剖面及钻孔岩芯特征为基础, 结合古地理背景, 总结了本区的石炭系地层特征, 认为石炭系地层具以下特点: (1)研究区位于醴陵—攸县断陷盆地的北部边缘地带, 沉积了樟树湾组这套高成熟度石英砂岩; (2)本区石炭系总体经历了多次海退-海进的循环沉积过程, 反映由陆架建设到碳酸盐台地的形成过程; (3)本区石炭系地层受地形条件控制及同生断裂的影响, 其沉积差异明显。本研究对醴陵地区石炭系石英砂岩矿的开发具指导意义。  相似文献   

http://www.sciencedirect.com/science/article/pii/S1674987114001352   总被引：8，自引：5，他引：3  

David E.Kelsey  Martin Hand 《地学前缘(英文版)》2015,6(3):311-356

Ultrahigh temperature(UHT) metamorphism is the most thermally extreme form of regional crustal metamorphism,with temperatures exceeding 900℃.UHT crustal metamorphism is recognised in more than 50 localities globally in the metaniorphic rock record and is accepted as 'normal' in the spectrum of regional crustal processes.UHT metamorphism is typically identified on the basis of diagnostic mineral assemblages such as sapphirine+ quartz,orthopyroxene + sillimanite ± quartz and osumilite in Mg-AIrich rock compositions,now usually coupled with pseudosection-based thermobarometry using internally-consistent thermodynamic data sets and/or Al-in-Orthopyroxene and ternary feldspar thermobarometry.Significant progress in the understanding of regional UHT metamorphism in recent years includes:(1) development of a ferric iron activity-composition thermodynamic model for sapphirine,allowing phase diagram calculations for oxidised rock compositions:(2) quantification of UHT conditions via trace element thermometry,with Zr-in-rutile more commonly recording higher temperatures than Ti-in-zircon.Rutile is likely to be stable at peak UHT conditions whereas zircon may only grow as UHT rocks are cooling.In addition,the extent to which Zr diffuses out of rutile is controlled by chemical communication with zircon;(3) more fully recognising and utilising temperature-dependent thermal properties of the crust,and the possible range of heat sources causing metamorphism in geodynamic modelling studies:(4) recognising that crust partially melted either in a previous event or earlier in a long-duration event has greater capacity than fertile,unmelted crust to achieve UHT conditions due to the heat energy consumed by partial melting reactions:(5) more strongly linking U-Pb geochronological data from zircon and monazite to P-T points or path segments through using Y + REE partitioning between accessory and major phases,as well as phase diagrams incorporating Zr and REE;and(6)improved insight into the settings and factors responsible for UHT metamorphism via geodynamic forward models.These models suggest that regional UHT metamorphism is,principally,geodynamically related to subduction,coupled with elevated crustal radiogenic heat generation rates.  相似文献   

湘西龙山江家垭铅锌矿床石英Rb-Sr同位素测年与示踪研究   总被引：3，自引：1，他引：2       下载免费PDF全文

周云  段其发陈毓川唐菊兴曹 亮甘金木 《中国地质》2015,(2):597-606

江家垭铅锌矿床位于扬子地台东南缘,红岩溪背斜轴部,是湘西—鄂西铅锌成矿带重要的铅锌矿床之一,铅锌矿体呈似层状和脉状,受地层与构造的控制,主要产于下奥陶统南津关组砂屑灰岩中。文章首次采用超低本底石英Rb-Sr同位素测年方法,对湘西龙山江家垭铅锌矿床主成矿期形成的富铅锌石英脉进行了等时线年龄测定,获得成矿年龄为(372±9.8)Ma,n(87Sr)/n(86Sr)=(0.709409±0.000058)。通过成矿地质背景探讨,认为该矿床的形成与晚泥盆世华南地区发生的拉张断陷导致的盆地流体大规模运动有关。锶同位素初始比值测试结果表明江家垭铅锌矿床成矿物质来源可能主要源自围岩碳酸盐岩,成矿过程中陆壳的影响较为明显。  相似文献