武夷山高溪和富城花岗岩体地球化学及其与铀成矿的关系   总被引：6，自引：2，他引：6  

陈迪云  章邦桐 《岩石学报》1997,13(1):71-84

从成矿地质条件分析，武夷火山铀成矿带中的主要铀矿床的共同点是都具有花岗岩基底岩石。选择富城和高溪两花岗岩体进行地球化学研究。这两个岩体均为复式岩基，其主体岩石都形成于印支晚期（高溪：２１４．６Ｍａ；富城：２０３～２２６Ｍａ）。岩体中的长石为微斜长石；黑云母为铁云母和铁叶云母。岩石化学表现为富硅、偏碱和铝过饱和的特征。微量元素Ｃｏ、Ｎｉ、Ｃｒ、Ｓｒ、Ｂａ含量和Ｓｒ／Ｂａ比值较低，Ｒｂ、Ｎｂ、Ｐｂ、Ｚｎ的含量和Ｒｂ／Ｓｒ比值高。稀土总量较高，轻稀土富集，轻、重稀土的比值高，并有强烈的铕亏损。高溪和富城两岩体的初始锶同位素组成高（分别为０．７１２３９和０．７１９８），钕同位素组成低（－６．６２～－１２．８４），这些表明高溪岩体属改造型花岗岩。两岩体中活性铀的比例高，特别是在蚀变作用中活性铀的比例增加。铅同位素追踪研究表明，在蚀变过程中岩体中的铀发生了大量的丢失。矿石铅同位素和岩体铅同位素都位于造山带的演化线附近，且矿石铅、火山岩铅、花岗岩铅及基底变质岩铅同位素组成呈线性关系，据此认为高溪和富城花岗岩体分别是形成５７０和６７２２矿床主要铀源体之一  相似文献   

Important Geological Factors Controlling the Formation of Gold Deposits in East China     

徐克勤  倪培等 《中国地球化学学报》1997,16(1):1-7

The major gold deposits in east China are characterized by their occurrence in pre-Cambrian host metamorphic rocks,restriction in some specific stratigraphic-structural terranes,tendentious localization in ductile or ductile-brittle shear zones,association with the syntexis type granitoids,and significant remobilization,superimposition and enrichment by the later stage Mesozoic tectono-magmatic activities.  相似文献   

Ages of Lueliang Group and Its Metamorphism in Mt.Lueliang Region,Shanxi Province：Evidence form Single Grain Zircon U—Pb Dating     

于津海  王德滋等 《中国地球化学学报》1997,16(2):170-177

Presented in this paper are the newly obtained grain zircon U-Pb ages of volcanic rocks of the Lueliang Goup and associated Kuanping granitic migmatitic gneiss in Shanxi Province.The zircon U-Pb ages of bimodal volcanic rocks(basalt and rhyolite)of the Upper Lueliang Group indicate that the rocks erupted at about 2100 Ma.So the Lueliang Group was formed during the Early Proterozoic.In the area studied the second-stage metamorphism experienced by the Lueliang Group is the dominant one which took place at about 1806 Ma.i.e.,during the late Early Proterozoic.  相似文献   

Crustal structure of Dabieshan orogenic belt   总被引：2，自引：0，他引：2  

Chunyong Wang  Xiankang Zhang  Buyun Chen  Xuebo Chen  Songyan Song  Jinhan Zheng  Hongxiang Hu  Hai Lou 《中国科学D辑(英文版)》1997,40(5):456-462

The crustal structures ofP velocity and density on the deep seismic sounding profile across the Ilabieshan orogenic belt are presented. There is a 5-km-thick crustal “root” between the Yuexi and Xiaotian where the elevation is highest on the profile. An apparent Moho offset of 4. 5 km beneath the Xiaotian-Mozitan fault marks the paleo-suture of the Triassic collision. A high-velocity anomaly zone at the depth below 3 km beneath the ultra-high pressure (UHP) zone may be correlated to the higher content of UHP metamorphic rocks. Project supported by the National Natural Science Foundation of China and the Joint Earthquake Science Foundation.  相似文献   

Assessment of hydrogeological conditions in basement aquifers of the Precambrian Oban massif, southeastern Nigeria   总被引：1，自引：0，他引：1  

A.E. Edet  C.S. Okereke 《Journal of Applied Geophysics》1997,36(4):195-204

A combined analysis of lineament length density from radar imagery and surface resistivity data is used to assess the hydrogeological conditions in the Oban massif, Nigeria. The results show that the data guided the qualitative and quantitative estimation of some aquifer parameters. These include resistivity of the water bearing formations (280–740 ω m), thickness (5–140 m), limited hydraulic conductivity (8.53-13.18 m/day) and transmissivity (410.65–725.88 m²/day) data. In addition, the lineament length density for the area ranged between less than 0.2 to slightly more than 0.4. Site evaluation for the location of productive boreholes/wells using a groundwater potential index (GWPI) indicates that areas with a GWPI of greater than 35 are consistent with relatively high yield.  相似文献   

煤的变质程度对焦炭结构构造的影响     

康西栋  胡善亭  潘治贵  潘银苗  王凌志 《吉林大学学报(地球科学版)》1997,(3)

从宏观和微观两方面对不同变质程度煤所形成焦炭的结构、构造进行了深入研究。从气煤到肥煤阶段（Ｒｏ，ｍ：０．７７％～１．１６％），焦炭气孔壁厚度逐渐增大；进入焦煤阶段（Ｒｏ，ｍ＞１．１６％），焦炭气孔壁厚度降低。气煤、１３焦煤形成的焦炭结构以各向同性体为主，焦煤、肥煤炼出的焦炭以粒状镶嵌结构为主。由气煤和高变质程度的焦煤形成的焦炭，其气孔以微孔和大孔为主，气孔分布标准差Ｄｓ最大；肥煤炼出的焦炭，其气孔分布大小较均一；１３焦煤和低变质程度的焦煤成焦后，气孔分布状况介于上述二者之间  相似文献   

张宣幔枝构造的成矿作用研究     

牛树银  孙爱群 《吉林大学学报(地球科学版)》1997,(4)

地幔热柱具有多级演化特征。河淮亚热柱顶部地幔物质以薄板状斜插至燕山造山带之下，燕山造山带轴部东西向尚义－赤城韧性剪切带与太行山构造岩浆带轴部北北东向乌龙沟－上黄旗韧性剪切带交汇叠加，使深部中下地壳应变软化岩石及深部幔源物质减压释荷产生深熔岩浆并上侵，从而加速了造山带的上隆速度，并可形成地幔热柱的第三级构造单元——幔枝构造。其中隆升较快的地段发育成为典型的变质核杂岩构造。幔枝构造控制着构造变形－岩浆活动－蚀变变质－成矿作用统一体系，并形成与幔枝构造密切相关的内带为金（铜钼）、外带为银（铅锌）多金属的成矿系列。论述了不同构造部位的成矿特征及其相关性、统一性。据此提出了在有利构造部位（参照已有矿点分布）扩大找矿和向深部扩大找矿的认识。  相似文献   

柴达木北缘超高压变质带中的岛弧火山岩   总被引：45，自引：3，他引：45       下载免费PDF全文

史仁灯  杨经绥  吴才来  Tsuyoshi IIZUKA  Takafumi HIRATA 《地质学报》2004,78(1):52-64

青藏高原北部柴北缘发育一套与超高压变质带并行的早古生代岛弧火山岩带,岛弧火山岩以玄武岩类为主,包括一些中酸性岩类,岩石以普遍遭受绿片岩相蚀变为特征,区别于该地区普遍遭受角闪岩相区域变质的元古代的基性火山岩。该早古生代的岛孤火山岩显示三组地球化学特征:①VTG-Ⅰ,岛弧拉斑玄武岩(IAT);②VTG-Ⅱ,高Al次钙碱性-碱性过渡型玄武岩;③VTG-Ⅲ,较N-MORB更亏损的拉斑玄武岩(异常MORB)。研究认为前两组火山岩是成熟岛弧两个发育阶段的特征性产物:洋壳俯冲到陆壳的初用,由俯冲洋壳和地幔楔的部分熔融形成岛弧拉斑玄武岩(IAT),随着俯冲板块的速度加快和岛弧周围地壳的加厚,则形成钙碱性玄武岩(CA)、高Al玄武岩。第三组火山岩形成于弧间盆地,由亏损的地幔楔高度部分熔融形成比N-MORB亏损的的火山岩(异常MORB)。岛弧火山岩的锆石LA-ICP-MS法U-Pb年龄为514.2±8.5 Ma,说明柴北缘在早古生代发生过洋壳向陆壳的俯冲作用。鉴于该地区代表陆-陆俯冲作用的柴北缘超高压变质岩石也是形成于早古生代(494Ma),认为陆-陆俯冲作用发生在洋-陆俯冲作用之后,二者时间和空间相伴随。  相似文献   

A comparative study on the illite crystallinity and the clay mineral reflectance spectral index for subdividing the very low-grade metamorphic belt along the Lizhou-Hekou geological section in the Youjiang sedimentary basin, Guangxi, China     

YAN Shouxun Laboratory of Remote Sensing Information Sciences  Institute of Remote Sensing Applications  Chinese Academy of Sciences  Beijing  China 《中国科学D辑(英文版)》2004,47(9)

To examine the application potential of hyperspectral remote sensing techniques in classifying very low-grade metamorphic belts, the composition of clay minerals and the cyrstallinity of illite from mudstones were measured using XRD and VIS-SWIR (400-2500 nm) reflectance spectroscopy. Based on the illite cyrstallinity, Kubler Index (KI), the Early Triassic LuoLou Group and the Middle Triassic lower Baifeng Formation were classified as the lower Epizone with KI△2θ° ranging from 0.22 to 0.25, the upper Baifeng Formation as upper anchizone with KI△2θ°ranging from 0.26 to 0.33, and the Hekou Formation as lower anchizone with KI△2θ° ranging from 0.38 to 0.40. According to a KI△2θ° value of 0.43, it is possible that there may exist a local diagenetic zone in the upper strata. The illite cyrstallinity Kubler index and the metamorphic grade increase from the bottom to the top of the stratigraphic sequence. The metamorphic grade boundaries nearly match the stratigraphic boundaries, indicating a burial metamorphism nature for the stratigraphic sequence. From the bottom to the top of the sequence, the spectral absorption band center of clay minerals from fresh rocks is around 2200 nm. The absorption band centers change towards shorter wavelengths: the Luolou Group being at 2220 nm, the Baifeng Formation at 2217-2213 nm, the lower member of the Hekou Formation at 2214-2206 nm, and the upper member of the Hekou Formation at 2205-2197 nm. The spectral absorption band center of illite shows the same change pattern. These results indicate that very low-grade metamorphic belts can be subdivided using spectral indices of clay minerals, which are measured by using field portable spectroradiometers. However, it may not work well with satellite and airborne sensors.  相似文献   

中国大陆科学钻探主孔100～2000米超高压变质岩中的钛矿化   总被引：14，自引：12，他引：14  

徐珏陈毓川  王登红余金杰李纯杰  傅旭杰陈振宇 《岩石学报》2004,20(1):119-126

中国大陆科学钻探工程100～2000m的岩心、矿心的观察、编录揭示主要有经济价值的舍钛相是金红石．其次是钛磁铁矿。主要含矿岩石是普通金红石榴辉岩和石英金红石榴辉岩，其次有多硅白云母金红石榴辉岩，蓝晶石金红石榴辉岩，金红石黑云绿帘纤闪石岩(退变的石榴辉石岩)和金红石-含钒钛磁铁矿榴辉岩。划分了四个矿化层位。金红石在矿层中的含量一般为2％～5％(体积)，多高达8％～10％。金红石的TiO2含量在95％(重量)以上，多产于石英榴辉岩、多硅白云母榴辉岩中。钛磁铁矿的TiO2含量在49％～55％(重量)，钛磁铁矿多见于黄铁矿-金红石-钛磁铁矿榴辉岩(546～608m岩性段)中，含钛磁铁矿5％～25％，石榴单辉橄榄岩(608～683m岩性段)，含钛磁铁矿达5％～10％和第三含矿层中局部黑云绿帘角闪岩夹层内，舍钛磁铁矿可达6％。30个榴辉岩和超铁镁质岩中8种主要造岩矿物148个点的电子探针分析结果揭示：榴辉岩可分为壳源和幔源两大类，钛磁铁矿富含V、Ni、Cr说明来自幔源，大部分金红石则来自壳源榴辉岩，它们的原岩是曾经居留地表的基性火成岩，在深俯冲的过程中经超高压变质成为含柯石英的榴辉岩。岩石薄片中金红石和柯石英的假像共存于同一石榴石或绿辉石晶粒中，也见金红石粒内有“柯石英”假象，这清楚说明金红石结晶于超高压的峰期变质阶段，在后继的变质地体隆升过程中，钛磁铁矿和金红石都有退变质成为钛铁矿和榍石的种种岩石记录，因此，退变质作用势必导致钛矿品位的降低。  相似文献