胶东文登长山南花岗闪长岩体的岩浆混合成因：闪长质包体及寄主岩石的地球化学、Sr-Nd同位素和锆石Hf同位素证据

胶东昆嵛山杂岩文登长山南花岗闪长岩体中广泛分布具有火成结构的闪长质包体,这些包体主要为椭圆形或纺锤形,定向排列,大小不等(几cm至几m),颜色较寄主岩深,粒度较细。包体具有与寄主岩石相似的矿物组合,但铁镁质矿物及斜长石含量明显比寄主岩石高,而石英和钾长石含量低于寄主岩石;镜下包体具有明显的不平衡反应结构,广泛发育针状磷灰石。在地球化学特征上,包体和寄主岩石部富集大离子亲石元素和轻稀土元素,亏损高场强元素,并具有相近的Sr、Nd同位素组成,ISr为0．70784-0．70818,εNd为-15．0--15．5。然而,包体和寄主岩石的主量元素在相关图上呈明显的线性关系, 并且岩石学和锆石Hf同位素特征也明显表明文登长山南岩体在成岩过程中发生了镁铁质岩浆和长英质岩浆的混合作用。在岩浆混合作用过程中,全岩Sr、Nd同位素和晚期生成的矿物组成比较快速地达到了均一化,而主量元素和高温矿物锆石Hf同位素组成则残留了原始岩浆的部分特征。研究表明,锆石Hf同位素在岩浆混合作用过程中不容易达到同位素平衡,其同位素组成比全岩Sr、Nd同位素更能有效地示踪混合岩浆的源区特征和岩浆混合过程。     

华南花岗岩暗色微粒包体的岩石化学组成特征及其意义

对华南诸多花岗岩体暗色微粒包体的野外调查表明, 非均一包体是包体中最普遍的类型,常具有暗色基性边.岩石化学分析结果表明,包体边缘的岩性为二长岩-石英二长岩-二长闪长岩,中心则为石英二长闪长岩-英云闪长岩.从包体中心到边缘,具有Si、Ca含量和Na/K比值降低,K、Al、Ti、P和Fe+Mg含量升高的变化趋势,揭示包体应...     

Petrological and Mineralogical Study of Enclaves in Plutons in the Typical Mining Districts of Tongling,Anhui and Its Bearing on the Process of Magmatism—Metallogeny

Two types of enclaves occur in magmatic plutons in Tongling,Anhui.Enclaves of the first type are residuals of metamorphic rocks of high amphibolite facies,and those of the other type are magmatic rocks ranging from monzonitic to dioritic in composition. A combined petrological and mineralogical study has been carried out on the two types of enclaves in order to estimate their forming conditions and analyze their relations to their hosts.so as to have an insight into the material sources of magmatic rocks and associated mineral deposits and give a clue to better understanding the mechanism of magmatism-metallogeny.This leads us to propose a new metallogenic model for strats-bound skarn-type ore deposits associated with a syntectic type of magmatic rocks.The new model can be simply summarized as partial melting of old metamorphic basement rocks at depth and accumulating,differentiating and positioning of magmas to form deep-level and shallow-level magma chambers,follower by mixing of different magmas associated with their crypto-explosion,migration of gas-bearing ore fluids and precipitation of metals in fluids within the magmas.     

Post-collisional plutonism with adakitic signatures： The Triassic Yangba granodiorite （Bikou terrane,northern Yangtze Block）

The post-collisional Yangba granodiorite intruded into the Bikou metasedimentary-volcanic group, southern Mianlue Suture, central China. The host granodiorites contain many mafic microgranular enclaves which have acicular apatite, phenocrysts of host granodiorites, implying that the enclaves have been incorporated as magma globules into host granodioritic magma and undergone rapid cooling. The variation trends of major and trace elements between enclaves and host rocks suggest a mixing and mingling process with respect to their petrogenesis. The mafic microgranular enclaves are characterized by shoshonite with SiO2≤〈63%, σ （4.54-6.18）〉3.3, high K2O content （4.22%-6.04%）, K2O/Na2O〉1; in the K2O-SiO2 diagram, all the samples plot in the shoshonite field, which are enriched in LILE and LREE, with obvious Nb, Ta negative anomalies, indicating a subducting fluid-metasomatised mantle source. Zircon LA-ICP-MS dating of the granodiorites yielded an age of 215.4±8.3 Ma, indicating they were formed during the late-orogenic or post-collisional stage （≤242±21 Ma） of the South Qinling Mountain Belt. The host granodiorites have many close compositional similarities to high-silica adakites from supra-subduction zone setting, but tend to have a higher concentration of K2O （3.22%-3.84%） and Mg^#. Chondrite-normalized rare-earth element patterns are characterized by high ratios of （La/Yb）N, the extreme HREE depletion and a lack of significant Eu anomalies. In conjunction with the high abundances of Ba and Sr as well as the low abundances of Y and HREE, these patterns suggest a feldspar-poor, garnet ± amphibole-rich fractionation mineral assemblage. High Mg^# values demonstrate that the host granodiorites were contaminated by enclave magma. On a whole, integrated geological and geochemical studies suggested the Yangba granodiorites and their mafic microgranular enclaves resulted from mixing of enriched mantle-derived shoshonitic magma and thickened lower crust-derived felsic magma. In combination w     

小兴安岭东南金山屯一带晚三叠世二长花岗岩成因及其地质意义

在小兴安岭东南端金山屯一带,广泛发育近南北向展布的晚三叠世似斑状二长花岗岩岩石组合,岩石中普遍见有暗色微细粒闪长质包体和中-基性脉岩群。对岩体及其包体、中-基性脉岩的宏观、微观特征和地球化学特征的研究表明,包体形态多呈浑圆的外形,显示出明显的塑性流变特点,具典型的岩浆结构包体中见针状磷灰石和含寄主岩钾长石、石英巨晶,具有明显的岩浆混合成因的包体特征;岩体的中-基性脉岩（群）形态多样,与花岗岩的界面或呈小波浪状或呈平直状,并见寄主岩长石斑晶,表现出壳幔混合作用形成的同深成岩墙群特征。该区晚三叠世二长花岗岩具显著的岩浆混合成因特征,其形成可能与碰撞后伸展动力学机制下的基性岩浆底侵作用有关。     

Current Research Status and Prospect of Tectonically Deformed Coal

A number of studies have shown that development areas of weak deformation brittle series of tectonically deformed coal are often the favorable areas for coalbed methane development, and the distribution area of the mylonitic coal of ductile deformation is a danger zone of mine gas outburst. Therefore, faced with solving the key scientific issues and technical problems of the coal bed methane exploration and development and gas outburst prediction and evaluation, more and more attention has been paid to the research on tectonically deformed coal. This paper first systematically elaborated the main research progress on the concept and classification of tectonically deformed coals, their deformation characteristics, and the pore fissure structure and chemical structure. Then, it pointed out that there was a lack of research on the ductile deformation mechanism of coal, and this key scientific problem needs further research in the future. It seemed that the structural and geochemical process of chemical elements migration and accumulation during coal deformation was a new field which is worth exploring. Through refining stress sensitive elements, their distribution and evolution patterns in different stress-strain environments and different types of tectonically deformed coals might be revealed, and then they could become a predictive index which indicates the significance of distribution of tectonically deformed coals and gas outburst prediction. It was thought that geophysical response characteristics and research of detection theory and interpretation method of different types of tectonically deformed coal and gas enrichment area should be an important development direction in the future.     

Multiple sources for the origin of granites: Geochemical and Nd/Sr isotopic evidence from the Gudaoling granite and its mafic enclaves, northeast China

Geochemical and Sr- and Nd-isotopic data have been determined for mafic to intermediate microgranular enclaves and host granitoids from the Early Cretaceous Gudaoling batholith in the Liaodong Peninsula, NE China. The rocks include monzogranite, porphyric granodiorite and quartz diorite. Monzogranites have relatively high ⁸⁷Rb/⁸⁶Sr ratios (0.672-0.853), low initial ⁸⁷Sr/⁸⁶Sr ratios (0.7052-0.7086) and ε _Nd(t) values (−18.5 to −20.9) indicating that they were mainly derived from a newly underplated crustal source with a short crustal residence time. Quartz diorites have high initial ⁸⁷Sr/⁸⁶Sr ratios (0.7118-0.7120) and negative ε _Nd(t) values (−13.2 to −18.1) coupled with high Al₂O₃ and MgO contents, indicating they were derived from enriched lithospheric mantle with contributions of radiogenic Sr from plagioclase-rich metagreywackes or meta-igneous rocks, i.e., ancient lower crust. Two groups of enclaves with igneous textures and abundant acicular apatites are distinguished: dioritic enclaves and biotite monzonitic enclaves. Dioritic enclaves have low Al₂O₃ (13.5-16.4 wt%) and high MgO (Mg# = ∼72.3) concentrations, low initial ⁸⁷Sr/⁸⁶Sr ratios (0.7058-0.7073) and negative ε _Nd(t) values (∼−7.2), and are enriched in LILEs and LREEs and depleted in HFSEs, suggesting they were derived from an enriched lithospheric mantle source. Biotite monzonitic enclaves have Sr and Nd isotopic compositions similar to the monzogranites, indicating they were crystal cumulates of the parental magmas of these monzogranites. Granodiorites have transitional geochemistry and Nd- and Sr-isotopic compositions, intermediate between the monzogranites, quartz diorites and the enclaves.Geochemical and Sr- and Nd-isotopic compositions rule-out simple crystal-liquid fractionation or restite unmixing as the major genetic link between enclaves and host rocks. Instead, magma mixing of mafic mantle-derived and juvenile crustal-derived magmas, coupled with crystal fractionation and assimilation of ancient lower crust, is compatible with the data. This example shows that at least some calc-alkaline granitoids are not produced by pure intracrustal melting, but formed through a complex, multi-stage hybridization process, involving mantle- and crustal-derived magmas and several concomitant magmatic processes (crystal fractionation, crustal assimilation and crustal anatexis).     

广西米场花岗岩及其暗色微粒包体的地球化学特征和成因分析

本文对博白-岑溪断裂带西南段的米场黑云母花岗岩体及其包体进行了岩石学和地球化学研究.结果表明,米场黑云母花岗岩体暗色包体广泛分布,暗色包体中发育有碱性长石斑晶、暗色镶边的眼球状石英、针状磷灰石和包裹有内环带的斜长石等.寄主岩及暗色包体两者都为准铝质、高钾钙碱性系列岩石,其主要氧化物含量在Harker图解中多呈直线变异趋...     

西准噶尔夏尔莆岩体岩浆混合的锆石U-Pb年代学证据

尽管岩相学标志是识别岩浆混合的最直接、最重要的证据,但其寄主岩石、幔源包体及基性岩墙群的精确同位素定年则是对岩浆混合证据的重要补充。夏尔莆岩体由寄主岩石、微细粒镁铁质包体和中基性岩墙群组成,高精度LA-ICP-MS锆石U-Pb测年表明三者的年龄分别为297.6±2.5Ma、298.2±8.0Ma、298.9±5.0Ma,在误差范围内一致,说明三者是同一岩浆事件的产物,为夏尔莆岩体岩浆混合成因提供了年代学证据。夏尔莆岩体的岩浆混合成因的确立证实了早二叠世西准噶尔地壳深部发生过强烈的壳幔岩浆混合作用,并导致了该地区一次重要的地壳垂向生长事件,而岩体中大量的微细粒镁铁质包体和中基性墙群正是这次生长事件的物质记录者。     

秦岭早中生代壳幔岩浆混合作用——来自东江口花岗岩体闪长质包体的地球化学证据

      东江口花岗岩及闪长质包体分别获得了218 Ma 和224 Ma 的形成年龄,闪长质包体中存在岩浆不平衡结构并发育与寄 主花岗岩相同的钾长石斑晶及淬冷形成的针状磷灰石,揭示了花岗岩形成过程中曾发生二元岩浆混合作用。这种混合作用 已造成寄主花岗岩和闪长质包体化学组成的趋同,同时使得它们的Sr-Nd-Pb 同位素组成发生强烈均一化。但暗色闪长质包 体锆石具有较宽的εHf（t ）值（-4.58~3.31）,保留了二端元岩浆源区的特征。秦岭早中生代同期闪长质包体锆石εHf（t ）＞ 10 及寄主花岗岩锆石εHf（t ）＜ -10 的差异表明,它们分别来自相对亏损地幔源区和中元古代滞留于地壳的幔源基性物质, 而两个源区的岩浆,自224 Ma 以来发生强烈混合作用,形成大规模的壳幔混合花岗岩体。