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   

冀北中生代高Sr低Y和低Sr低Y型花岗岩：地球化学、成因及其与成矿作用的关系   总被引：20，自引：22，他引：20  

李承东 张旗苗来成  孟宪锋 《岩石学报》2004,20(2):269-284

冀北是我国重要的金矿成矿区，冀北金矿有不同的类型，但大多与中生代中酸性侵入岩有关。本文的研究表明，冀北与金矿有关的中酸性侵入岩大体可划分为两类：一类为高Sr低Y型岩体，具有埃达克质岩的地球化学特征。推测可能是加厚的下地壳部分熔融形成的，其残留相为榴辉岩或角闪榴辉岩；另一类为低Sr低Y型岩体，以较低的Sr、Al和具明显的负铕异常而区别于埃达克质岩，又因其低Y和HREE而类似于埃达克质岩，推测源岩残留相中有斜长石存在，相当于高压麻粒岩相的环境，可能也形成于加厚下地壳底部。冀北金矿的S、Ph、H、O和C同位素大多显示深源的特点,且在时空分布上与上述两类中酸性侵入岩存在密切的关系，表明冀北金矿床的成矿物质和流体可能是幔源的，与中生代高Sr低Y和低Sr低Y型岩浆的成因有关。这一认识对于理解冀北金矿的成因和找矿可能是有益的。  相似文献   

Integrated approach of using ASTER-derived emissivity and pixel temperature for delineating different granitoids – a case study in parts of Dharwar Craton,India     

Arindam Guha  K. Vinod Kumar 《国际地球制图》2016,31(8):860-869

We have delineated different granitoids based on variation in emissivity and relative surface temperature recorded in thermal bands of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) sensor of EO-1 satellite. In this regard, we have used emissivity normalization algorithm to derive broadband emissivity from thermal bands of ASTER sensor to delineate different lithounits of the granitoid family. We have compared emissivity and radiance image composites in terms of delineation of different granitoids. We have also used false colour composite (FCC) image derived using two emissivity bands and temperature (derived using emissivity normalisation method) bands to delineate different granitoids. We could differentiate different granitoids in the three-dimensional (3D) data space of ASTER-derived emissivity bands (second and third bands) and temperature bands. Based on the analysis of 3D scatter plot, we also proposed a ternary diagram of emissivity and temperature, which can be used to delineate different granitoids.  相似文献   

西准噶尔成矿带晚古生代花岗岩类岩浆活动及其构造意义   总被引：1，自引：0，他引：1  

黄鹏辉  陈宣华  王志宏  叶宝莹  李学智  杨屹 《大地构造与成矿学》2016,(1):145-160

中亚造山带是晚古生代地壳显著生长与大规模成矿的重要地区。本文采集了中亚造山带西部的西准噶尔成矿带哈图-别鲁阿嘎希及其附近地区11个岩体共33件花岗岩类样品,对其开展了岩石地球化学与同位素示踪等研究,厘定了该地区晚古生代岩浆活动的特点与大地构造环境,并与哈萨克斯坦境内的巴尔喀什成矿带晚古生代岩浆活动进行了对比。研究表明,哈图地区晚石炭世花岗岩类主要为后碰撞伸展构造环境的A型花岗岩类,别鲁阿嘎希等地区存在洋内俯冲与岛弧环境的埃达克岩,显示了西准噶尔晚古生代构造环境时空变化的复杂性。该地区花岗岩类εNd(t)值较高(+4.62~+7.53)、εSr(t)值为(-57.61~+18.21),具有中亚造山带花岗岩类的共同特征,为古生代增生的新生陆壳,其源区与亏损地幔组分具有亲缘关系,这与巴尔喀什成矿带东段的花岗岩类具有一致性。花岗岩的~(206)Pb/~(204)Pb、~(207)Pb/~(204)Pb和~(208)Pb/~(204)Pb比值范围分别为18.2776~19.1677、15.5260~15.5796和38.2080~39.0821,为造山带花岗岩类。  相似文献   

Late mesozoic A-Type granitoids in se China and paleo-pacific plate subduction and slab rollback北大核心CSCD     

Xia Y.  Liu L.  Xu X.-S. 《矿物岩石地球化学通报》2016,(6):1109-1119

This study has reviewed the distribution and pedogenesis of late Mesozoic A-Type granitoids in SE China. These A-Type granitoids belong to four belts ( S Jiangxi-SW Fujian belt, Xiang-Gui-Yue belt, Can-Hang belt and coastal belt) due to their temporal-spatial distribution. Based on the comparative analysis of chronology, geochemistry and magmatic association, this study has discussed the formation of A-Type granitoids and the subduction and slab rollback process of paleo-Pacific plate beneath SE China.  相似文献   

Apatite Composition of Representative Magnetite‐series and Ilmenite‐series Granitoids in Japan          下载免费PDF全文

Shunso Ishihara  Takeru Moriyama 《Resource Geology》2016,66(1):55-62

Apatites of representative magnetite‐series and ilmenite‐series granitoids were studied in the Japanese Islands. Concentrations of the volatile components F, Cl and SO₃ are differently distributed in apatites of these granitoid series. Apatites are always fluoroapatite. They have weakly higher F content in the ilmenite series than in the magnetite series. In contrast, Cl and SO₃, are significantly concentrated in apatites of the magnetite series compared to the ilmenite series. These characteristics reflect the original concentrations of these components in the host granitic magmas. A high fO₂ seems most important for the S‐concentration as sulfate in apatite of the magnetite series. REE and Y are only erratically high in the studied apatites.  相似文献   

Early Proterozoic granitoids of the Olenek complex (northern Siberian craton): petrogenesis and geodynamic setting     

T.V. Donskaya  D.P. Gladkochub  A.M. Mazukabzov 《Russian Geology and Geophysics》2018,59(3):226-237

The paper deals with geological and geochemical studies of granitoids of the Olenek complex in the Olenek uplift of the basement of the northern Siberian craton. The age of these granitoids was earlier estimated at 2036 ± 11 Ma. The granitoids of the Olenek complex correspond in composition to high-alumina quartz diorites, granites, and leucogranites of the normal petrochemical series. According to geochemical and mineralogical characteristics, the quartz diorites can be assigned to granites of the transitional I-S type, and the granites and leucogranites, to S-type granites. The 8_Nd(T values in the granites of the Olenek complex vary from -0.2 to + 1.4, and the Nd model age is 2.4-2.5 Ga. The quartz diorite is characterized by 8_Nd(T) = + 3.0 and a Nd model age T(DM) = 2.2 Ga. The geochemical characteristics of the granites and leucogranites indicate their formation through the melting of a source of graywacke composition, whereas the quartz diorites resulted, most likely, from the mixing of granitic and basaltic melts. The fact that the granitoids of the Olenek complex intruded the folded rocks of the Eekit Formation but stay virtually undeformed massive bodies suggests that they formed at the postdeformation stage of the regional evolution after the completion of the Paleoproterozoic orogenic events. The intrusion of granitoids marks the completion of the formation of the Early Proterozoic Eekit fold belt on the western (in the recent coordinates) margin of the Birekta terrane of the Olenek superterraine and the final formation of the superterrane structure. At the next stage of magmatism (1.98-1.96 Ga), best pronounced in the uplifts of the basement of the northern Siberian craton, all terranes forming the Anabar and Olenek superterranes assembled into a single structure.  相似文献   

武夷山中段司前花岗岩体形成时代、地球化学特征及地质意义     

辛宇佳  李建华  董树文  张岳桥 《地球学报》2018,39(3):269-281

本文对武夷山中段的司前岩体进行了系统的岩石学、地球化学、年代学及Lu-Hf同位素研究。结果表明,司前岩体形成于(140±1)Ma,主要由黑云母二长花岗岩组成,富碱(K_2O+Na_2O=6.67 wt%~8.25 wt%),富钾(K_2O/Na_2O=1.16~2.41),A/CNK值介于1.01~1.25之间。岩体具有较高的∑REE(177.73×10~(-6)~427.88×10~(-6))、Zr+Nb+Y+Ce含量(262.6×10~(-6)~581.5×10~(-6))和Zr饱和温度(平均824°C),FeOt/MgO(3.06~3.93)和10 000×Ga/Al(2.64~3.28)比值均较高,属典型的铝质-过铝质A型花岗岩。岩体的锆石εHf(t)值均为负值(–18.6~–7.9),暗示其源于古老的地壳物质重熔。综合上述结果和区域背景推测,司前岩体的源岩为新元古代麻源群变质火山-碎屑岩,源岩可能经历早古生代和白垩纪两期熔融事件,地幔岩浆为花岗岩的形成提供了热源,但并未贡献物质,岩体的形成与古太平洋板块俯冲过程中因俯冲板片后撤诱发的弧后扩张作用有关。  相似文献   

Constraints of Mantle and Crustal Sources Interaction during Orogenesis of Pre- and Post-collision Granitoids from the Northern Arabian-Nubian Shield: A Case Study from Wadi El-Akhder Granitoids,Southern Sinai,Egypt     

Moustafa M. MOGAHED  Khaled M. ABDELFADIL 《《地质学报》英文版》2021,95(5):1527-1550

The Egyptian older and younger granitic rocks emplaced during pre- and post-collision stages of Neoproterozoic Pan-African orogeny, respectively, are widely distributed in the southern Sinai Peninsula, constituting 70% of the basement outcrops. The Wadi El-Akhder, southwestern Sinai, is a mountainous terrain exposing two granitoid suites, namely the Wadi El-Akhder Older Granites (AOG) and the Homra Younger Granites (HYG). The AOG (granodiorites with subordinate tonalite compositions) have geochemical characteristics of medium-K calc-alkaline, metaluminous to mildly peraluminous granitoids formed in an island-arc environment, which are conformable with well-known Egyptian older granitoids rocks, whereas the HYG display calc-alkaline to slightly alkaline nature, peraluminous syeno-, monzogranites and alkali feldspar granites matching well those of the Egyptian younger granites. With respect to the AOG granitoids, the HYG granites contain lower Al2O3, FeO*, MgO, MnO, CaO, TiO2, Sr, Ba, and V, but higher Na2O, K2O, Nb, Zr, Th, and Rb. The AOG are generally characterized by enrichment in LILE and LREE and depletion in HFSE relative to N-MORB values (e.g., negative Nb and Ta anomalies). The geochemical features of the AOG follow assimilation-fractional crystallization (AFC) trends indicative of extensive crustal contamination of magma derived from a mantle source. The chemical characteristics of the AOG are remarkably similar to those of subduction-related granitoids from the Arabian-Nubian Shield (ANS). The compositional variations from monzogranites through syenogranites to alkali feldspar granite within HYG could not be explained by fractional crystallization solely. Correlating the whole-rock composition of the HYG to melts generated by experimental dehydration melting of meta-sedimentary and magmatic rocks reveals that they appear to be derived by extended melting of psammitic and pelitic metasediments, which is similar to the most of younger granitic suites in the ANS.  相似文献   

阿拉善地块南缘古生代花岗岩类研究进展          下载免费PDF全文

于锴  武磊  王二腾  郭志昂  王赟  王金荣 《甘肃地质》2021,(2):23-29

阿拉善地块处于华北克拉通,塔里木克拉通和祁连造山带的交汇处,其南缘古生代花岗岩广泛分布。结合近年来阿拉善南缘古生代花岗岩研究成果,从锆石U-Pb年代学和地球化学等方面进行分析总结,认为阿拉善南缘早古生代花岗岩主要受控于祁连造山带的构造演化,其岩浆活动可分为两期,中奥陶世—早志留世和中志留世—早泥盆世,前者处于俯冲环境,后者为后碰撞伸展环境;晚古生代花岗岩仅零星出露于龙首山地区,岩石地球化学特征与宗乃山—沙拉扎山构造带花岗岩相似,与中亚造山带的构造演化相关。并对目前研究中存在的问题和未来研究的方向提出了建议。  相似文献