Contrast in Fluid M etallogeny between the Tianmashan Au-S Deposit and the Datuanshan Cu Deposit in Tongling, Anhui Province     

LEE Hyun Koo 《《地质学报》英文版》2003,77(1):116-124

A comprehensive contrast of ore-forming geological background and ore-forming fluid features, especially fluid ore-forming processes, has been performed between the Tianmashan and the Datuanshan ore deposits in Tongling, Anhui Province. The major reasons for the formation of the stratabound skarn Au-S ore deposit in Tianmashan and the stratabound skarn Cu ore deposit in Datuanshan are analyzed in accordance with this contrast. The magmatic pluton in Tianmashan is rich in Au and poor in Cu, but that in Datuanshan is rich in Cu and Au. The wallrock strata in Tianmashan contain Au-bearing pyrite layers with some organic substance but those in Datuanshan contain no such layers. Moreover, the ore-forming fluids in Tianmashan are dominantly magmatic ones at the oxide and sulfide stages, but those with high content of Cu in Datuanshan are mainly groundwater fluids. In addition, differences in compositional evolution and physicochemical condition variation of the ore-forming fluids result in gradual dispersion  相似文献   

Re-Os Age of Cu-Ni Ores from the Huangshandong Cu-Ni Sulfide Deposit in the East Tianshan Mountains and Its Implication for Geodynamic Processes   总被引：4，自引：0，他引：4  

MAO Jingwen  YANG Jianmin  QU Wenjun  DU Andao  WANG Zhiliang  HAN Chunming Faculty of Geosciences  Resources  China University of Geosciences  Beijing  E-mail: jingwenmao@.netInstitute of Mineral Resources  Chinese Academy of Geological Sciences  Beijing National Research Center of Geoanalysis  Chinese Academy of Geological Sciences  Beijing 《《地质学报》英文版》2003,77(2):220-226

An isochron age of 282±20 (95% conf. limit) Ma of the sulfide ores in the Huangshandong Cu-Ni sulfide deposit, the East Tianshan Mountains has been obtained through Re-Os isotopic measurement. The age implies that the Cu-Ni sulfide deposit and other related deposits in the same area occurred in a Permian extensional environment of post-collision instead of Devonian-Early Carboniferous ophiolite-related oceanic or island arc environments inferred before. It shares the same ages with the orogenic and epithermal gold deposit systems in the same area. An initial 187Os/188Os ratio of 0.25±0.04 (1σ) and a γos value of 99 on average display the participation of large quantities of crustal components into the rock-forming and ore-forming system during mineralization and magmatic emplacement.  相似文献   

辽宁地区的幔枝构造          下载免费PDF全文

白永俊  夏洪宝  赵艳秋 《地质找矿论丛》2003,18(Z1):1-6

将辽宁地区划分为4个幔枝构造:山海关幔枝、辽东南幔枝、建平-阜新幔枝、西丰幔枝,文章分述了它们各自组成与构造特点,并举例说明了辽宁幔枝构造通过其三个次级构造单元对成矿的控制规律.  相似文献   

云南泸沽湖畔石炭系-二叠系生物地层再研究     

董致中 《云南地质》2003,22(2):200-205

着重讨论沪沽湖畔相当于石炭系(三分)上统马平阶地层的划分和对比。认为其大部属于我国二叠系(三分)的下二叠统紫松阶(阿瑟尔阶—萨克马尔阶)，上部的硅质页岩已进入隆林阶(亚丁斯克阶)。根据岩性特征及古生物混生现象，推测除顶部外，大部为斜坡相沉积。其中的部分生物应是再沉积产物。  相似文献   

Temporal variations in magma composition at Merapi Volcano (Central Java, Indonesia): magmatic cycles during the past 2000 years of explosive activity   总被引：1，自引：0，他引：1  

Ralf Gertisser  Jrg Keller 《Journal of Volcanology and Geothermal Research》2003,123(1-2):1

Merapi Volcano (Central Java, Indonesia) has been frequently active during Middle to Late Holocene time producing basalts and basaltic andesites of medium-K composition in earlier stages of activity and high-K magmas from 1900 ¹⁴C yr BP to the present. Radiocarbon dating of pyroclastic deposits indicates an almost continuous activity with periods of high eruption rates alternating with shorter time spans of distinctly reduced eruptive frequency since the first appearance of high-K volcanic rocks. Geochemical data of 28 well-dated, prehistoric pyroclastic flows of the Merapi high-K series indicate systematic cyclic variations. These medium-term compositional variations result from a complex interplay of several magmatic processes, which ultimately control the periodicity and frequency of eruptions at Merapi. Low eruption rates and the absence of new influxes of primitive magma from depth allow the generation of basaltic andesite magma (56–57 wt% SiO₂) in a small-volume magma reservoir through fractional crystallisation from parental mafic magma (52–53 wt% SiO₂) in periods of low eruptive frequency. Magmas of intermediate composition erupted during these stages provide evidence for periodic withdrawal of magma from a steadily fractionating magma chamber. Subsequent periods are characterised by high eruption rates that coincide with shifts of whole-rock compositions from basaltic andesite to basalt. This compositional variation is interpreted to originate from influxes of primitive magma into a continuously active magma chamber, triggering the eruption of evolved magma after periods of low eruptive frequency. Batches of primitive magma eventually mix with residual magma in the magmatic reservoir to decrease whole-rock SiO₂ contents. Supply of primitive magma at Merapi appears to be sufficiently frequent that andesites or more differentiated rock types were not generated during the past 2000 years of activity. Cyclic variations also occurred during the recent eruptive period since AD 1883. The most recent eruptive episode of Merapi is characterised by essentially uniform magma compositions that may imply the existence of a continuously active magma reservoir, maintained in a quasi-steady state by magma recharge. The whole-rock compositions at the upper limit of the total SiO₂ range of the Merapi suite could also indicate the beginning of another period of high eruption rates and shifts towards more mafic compositions.  相似文献   

山西宁武陆相二叠系-三叠系界线剖面的磁化率研究   总被引：2，自引：0，他引：2  

袁爱华  朱宗敏  林文姣  刘育燕 《地质科技情报》2003,22(3):37-40

通过对山西宁武陆相二叠系—三叠系剖面的孙家沟组至刘家沟组磁化率的研究，发现该剖面自孙家沟组顶部的粘土岩层至刘家沟组底部，存在着明显的磁化率值升高的现象，认为该现象是由于气温升高和火山事件的影响。对比山西宁武剖面与浙江长兴海相剖面以及贵州威宁陆相剖面二叠系—三叠系界线附近的磁化率研究成果，发现三者具有很好的一致性。这表明，该磁化率值明显升高的现象具有跨区(晋、淅、黔)和跨相(陆、海)的区域性特征，可用于地层的划分和对比。根据磁化率的研究结果，建议将山西宁武剖面的二叠系—三叠系界线设在磁化率值明显升高的地方，印17层顶部纹层粉砂岩之下的粘土岩层。  相似文献   

Paléoenvironnements et caractérisation des roches mères pétrolières des séries pré-salifères du bassin intérieur du Gabon     

Michel Mbina Mounguengui  François Baudin  Jacques Lang  Olivier Jocktane 《Comptes Rendus Geoscience》2003,335(3):327-334

The Interior Basin of Gabon, created during the break-up between South America and Africa, displays thick Neoproterozoic to Aptian p.p. fluvio-lacustrine deposits overlain by Aptian to Albian marine facies. Rock–Eval analyses from outcrop and drillhole samples show high content in organic matter (up to 25%) related to types I and II. These intervals are encountered within Permian, Neocomian–Barremian as well as Aptian siliciclastic succession. They constitute fairly good to excellent potential petroleum source rocks, which are most probably at the origin of oil indices recognized both in drillholes and in surface.  相似文献   

福建龙永煤田二叠纪(竹蜓)生物带的面貌特征与对比     

胡兆曦 《中国煤田地质》2003,(4)

研究地层是有效寻找沉积矿产的重要基础,将龙永煤田内关于的层位及分带性与大区域上的相似层位作了对比,并论述了本煤田的特征与变迁的基本过程。最后,结合多年来的研究成果,就煤田内的产出情况,作了两点必要的说明。  相似文献   

东昆仑造山带花岗岩类Pb-Sr-Nd-O同位素特征   总被引：19，自引：1，他引：19  

刘成东  莫宣学  罗照华  喻学惠  谌宏伟  李述为  赵欣 《地球学报》2003,24(6):584-588

本文报道了东昆仑造山带三叠纪辉长岩、花岗岩类及其包裹体的Pb、Sr、Nd和O同位素组成。东昆仑造山带花岗质岩石全岩和长石Pb同位素组成相差不大，具明显的造山带Pb同位素特征；Sr同位素初始值(ISr)变化于0．70144～0．70972之间，暗示幔源成因；εNd值变化于-4．49939～-9．19258之间，具壳源成因特点；Nd同位素模式年龄(tDM)在1．38～1．761Ga之间，与中元古代变质岩相当；O同位素组成变化范围7．8～9．5，表明花岗岩类成岩物质主要来自地壳。综合岩石的同位素组成，结合矿物学、岩石地球化学的研究，表明花岗岩浆主要起源于地壳，但与来自地幔的基性岩浆曾发生过混合作用，从而导致同位素组成趋于一致。  相似文献   

湘鄂赣二叠纪沉积盆地与层序地层   总被引：5，自引：2，他引：5  

牟传龙  丘东洲  王立全  万方 《沉积与特提斯地质》1997,17(5):1-26

湘鄂赣二叠纪沉积盆地是在统一的陆愉－－华南陆块基础上发展而来的，根据晚古生代以来的地壳活动情况、沉积物充填序列、沉积相带及空间配置，该区可以划分为四种沉积盆地，即扬子克拉通盆地、扬子克拉通缘被动大陆边缘盆地、湘赣板内拉张盆地和华夏克拉能边缘盆地。由于没沉积盆地中层序发展的主控因素及上关效应的差异，从而决定了层序发育特点的差异，本文详细划分了各种沉积层序和沉积体系域，并进行了区域对比。在此基础上，探  相似文献