Distribution Characteristics and Metallogenic Regularity of Graphite Deposits in Qinling Orogen, China     

FENG Yangwei  QU Hongjun  YANG Chenyi  LV Lushi 《《地质学报》英文版》2015,89(4):1244-1263

Qinling orogen is one of the five main repository distribution provinces of large scale graphite resources. Graphite occurrence strata are multitudinous including Neo Archaean group to Neopaleozoic. Mineral deposit types are complete consisting of crystal flaky graphite deposit and aphanitic graphite deposit, ore types of the former are main graphite gneiss, graphite schist and graphitized marble, and ore types of the latter are main graphite layer metamorphosised from coal bed and graphitic carbargilite. At present, most graphite deposits with low research degree only implement preliminary investigations of the graphite resource, which has a good prospect. Based on the basic material of dozens of graphite deposits, spots and plays discovered in the Qinling orogen, this paper applied geologic multidisciplinary analysis method to disclose the graphite deposit types of the Qinling orogen, mainly through outdoors geologic survey and specimen examination with analysis of some typical deposits: regional metamorphism crystal graphite deposits and thermo-contact metamorphic aphanitic graphite deposits, with the control of latitudinally trending regional tectonic, graphite deposits of the Qinling orogen distribute sublatitudinally trending three large ore belts: I the Neoarchean–Proterozoic basement crystal graphite enrichment deposits zone along the south margin of North China plate; II the Carboniferous intermountain basin group aphanitic graphite enrichment deposits zone near the Shangdan suture of the West Qinling; III Paleozoic crystal graphite enrichment deposits zone in the Qinling paleomicroplate of the west part of the East Qinling.Conclusions are reached from multiple inquiries: Qinling multi-cycle complex continental collision orogen zone has experienced multiple tectonic framework transformation and polyphase tectonic thermal event from Neo Archean Erathem adjointing multiple graphite tectonic mineralization cycle. In the light of chief control of mineralization and ore types, each of the three large graphite deposits belts of the Qinling orogen has its own genesis: I graphite deposits enriched metallogenetic zone is that regional tectogenetic movement from Neo Archaean caused polyphase metapepsis, which superimposed up and reconstructed Neo Archean Erathem to Proterozoic basement, forming regional metamorphic big flake crystal graphite deposits; II graphite deposits enriched metallogenetic zone is that polyphase regional tectogenetic movement associated with multiple heating caused by multiphase igneous intrusion, which resulted in original coal layers emerging multiple thermo-contact metamorphisms and formed thermo-contact metamorphic aphanitic graphite deposits. III graphite deposits enriched metallogenetic zone is that Palaeozoic cap–rock experienced polyphase metapepsis, forming regional metamorphic finely flake crystal graphite deposits. Comprehensive research of metallogenetic mechanism in graphite deposits and its associated profitable deposits of the Qinling orogen is importance for future exploration.  相似文献   

西盟地区奥陶纪花岗片麻岩的锆石U-Pb年代学、Hf同位素组成特征及其大地构造意义   总被引：2，自引：0，他引：2  

邢晓婉  张玉芝  王岳军  刘汇川 《大地构造与成矿学》2015,(3)

对云南西部侵入于原西盟群帕可组的花岗片麻岩开展主量元素、锆石U-Pb年龄及原位Hf同位素组成分析。岩石地球化学特征显示其为高钾钙碱性强过铝质S型花岗岩,两件代表性样品分别给出了461.4±2.5 Ma和461.5±3.3 Ma的206Pb/238U加权平均年龄,相应的锆石εHf(t)值分别介于-6.45~-1.90和-5.60~-1.44之间,二阶段模式年龄(tDM2)分别为1.57~1.86 Ga和1.54~1.90 Ga。这些数据表明西盟地区侵入于原西盟群帕可组内的花岗片麻岩并非前人所认为的中元古代岩石,而是中奥陶世产物,其源岩可能是元古宙变质杂砂岩。结合前人研究成果,作者推测西盟地区早古生代花岗片麻岩是环冈瓦纳大陆边缘安第斯型造山作用的产物。  相似文献   

内蒙古大青山北麓蓝晶石榴长英质片麻岩的发现:岩相学、地球化学和锆石SHRIMP定年   总被引：5，自引：0，他引：5       下载免费PDF全文

徐仲元  刘正宏  董晓杰  董春艳  万渝生 《地质论评》2011,57(2):243-252

最近1:5万地质填图发现,在华北克拉通西部阴山地块西乌兰不浪地区的高级变质杂岩中,存在一套由蓝晶石榴长英质片麻岩、石墨蓝晶石榴长英质片麻岩、石墨石榴长英片麻岩和石榴蓝晶石英岩构成的岩石组合(蓝晶石榴长英质片麻岩组合).它们以构造残片形式产于由太古宙兴和岩群和紫苏石英闪长质-紫苏斜长花岗质-紫苏花岗质片麻岩(狼牙山片麻岩...  相似文献   

赞皇前寒武纪变质杂岩区变质反应结构与变质作用P-T-t轨迹   总被引：4，自引：4，他引：0  

肖玲玲  蒋宗胜  王国栋  万渝生  王涛  吴春明 《岩石学报》2011,27(4):980-1002

赞皇变质杂岩位于华北克拉通中部造山带中南段、太行山东麓低山区。出露于该变质杂岩区中南部的含石榴石的斜长角闪片麻岩、泥质片麻岩,均保存了三期矿物组合:进变质、峰期变质和退变质矿物组合。这两大类变质岩石中,进变质阶段矿物组合(M₁)以石榴石变斑晶核部的包裹体矿物组合为代表,变质高峰期矿物组合(M₂)由石榴石变斑晶"边部"和基质矿物组成,退变质阶段矿物组合(M₃)主要是环绕石榴石边部发育的"白眼圈"状后成合晶矿物组合。泥质片麻岩中的石榴石变斑晶均保存了明显的成分环带,且在边部很窄的范围内X_Mn有所增加、Mg/(Mg+Fe)有所降低,指示存在变质高峰期后的退变质过程。温度与压力计算结果表明,赞皇斜长角闪片麻岩所经历的进变质阶段(M₁)温度约为640~710℃、 压力约为8.2~8.6kbar;高峰期(M₂)变质温度超过810℃,压力大于12.1kbar;退变质阶段(M₃)的温压范围为590~670℃和3.2~5.6kbar。此前的研究已说明泥质片麻岩的进变质阶段(M₁)变质温度为660~690℃,压力为9.0~9.2kbar;高峰期(M₂)变质温度超过780℃,压力大于12.5kbar。变质高峰属于中压相系的顶部至高压相系的底部。斜长角闪片麻岩、泥质片麻岩均记录了典型的顺时针P-T轨迹,并显示近等温减压(ITD)的退变质片段。对泥质片麻岩中多颗锆石的变质增生边的SHRIMP U-Pb定年表明,变质高峰期时代为1821±17Ma。变质作用历史说明赞皇变质岩区卷入了华北克拉通东部陆块和西部陆块之间的俯冲-碰撞、随后的快速隆升过程,为华北克拉通中部造山带早元古代末期(~1850Ma)存在的造山事件提供了新的证据 。  相似文献   

贺兰山北段贺兰山岩群富铝片麻岩碎屑锆石LA-ICP-MS U-Pb定年及区域对比   总被引：6，自引：1，他引：5  

校培喜  由伟丰  谢从瑞  李平  白生明 《地质通报》2011,30(1):26-36

贺兰山北段贺兰山岩群中发育一套富铝片麻岩,Al2O3含量较高,总体与粘土质岩石化学成分相似,显示孔兹岩系的特征,变质矿物组合主要为石榴子石、堇青石、硅线石、十字石、紫苏辉石等,变质级别达角闪岩相—麻粒岩相。从宗别立岩组含石榴矽线黑云二长片麻岩中选取100粒各种类型的锆石进行了LA-ICP-MS U-Pb同位素测年,获得47个测年数据,锆石年龄多数介于1.80~2.15Ga之间,峰值为2.00~2.05Ga。碎屑锆石年龄频谱图与鄂尔多斯地块北缘的集宁岩群和乌拉山岩群十分相似,总体与吕梁构造运动的时限一致,为华北克拉通成熟陆壳演化阶段的产物,证明孔兹岩系形成于古元古代,之后长期处于稳定状态,很少受到构造热事件的干扰。  相似文献   

SHRIMP U–Pb ages of ultrahigh-pressure and retrograde metamorphism of gneisses, south-western Sulu terrane, eastern China     

Fulai Liu  Zhiqin Xu  J. G. Liou  Biao Song 《Journal of Metamorphic Geology》2004,22(4):315-326

Laser Raman spectroscopy and cathodoluminescence (CL) images reveal that most zircon separated from paragneiss and orthogneiss in drillhole CCSD‐PP2 at Donghai, south‐western Sulu terrane, retain low‐P mineral‐bearing inherited cores, ultrahigh‐pressure (UHP) mineral‐bearing mantles and low‐P mineral‐bearing (e.g. quartz) rims. SHRIMP U–Pb analyses of these zoned zircon identify three discrete and meaningful age groups: Proterozoic protolith ages (> 680 Ma) are recorded in the inherited cores, the UHP metamorphic event in the coesite‐bearing mantles occurred at 231 ± 4 Ma, and the late amphibolite facies retrogressive overprint in the quartz‐bearing rims was at 211 ± 4 Ma. Thus, Neoproterozoic supracrustal protoliths of the Sulu UHP rocks were subducted to mantle depths in the Middle Triassic, and exhumed to mid‐crustal levels in the Late Triassic. The exhumation rate deduced from the SHRIMP data and metamorphic P–T conditions is 5.0 km Ma^?1. Exhumation of the Sulu UHP terrane may have resulted from buoyancy forces after slab break‐off at mantle depths.  相似文献   

Field evidence,mineral chemical and geochemical constraints on mafic-felsic magma interactions in a vertically zoned magma chamber from the Chotanagpur Granite Gneiss Complex of Eastern India     

Bibhuti Gogoi  Ashima Saikia  Mansoor Ahmad 《Chemie der Erde / Geochemistry》2018,78(1):78-102

The Nimchak granite pluton (NGP) of Chotanagpur Granite Gneiss Complex (CGGC), Eastern India, provides ample evidence of magma interaction in a plutonic regime for the first time in this part of the Indian shield. A number of outcrop level magmatic structures reported from many mafic-felsic mixing and mingling zones worldwide, such as synplutonic dykes, mafic magmatic enclaves and hybrid rocks extensively occur in our study domain. From field observations it appears that the Nimchak pluton was a vertically zoned magma chamber that was intruded by a number of mafic dykes during the whole crystallization history of the magma chamber leading to magma mixing and mingling scenario. The lower part of the pluton is occupied by coarse-grained granodiorite (64.84–66.61?wt.% SiO₂), while the upper part is occupied by fine-grained granite (69.80–70.57?wt.% SiO₂). Field relationships along with textural and geochemical signatures of the pluton suggest that it is a well-exposed felsic magma chamber that was zoned due to fractional crystallization. The intruding mafic magma interacted differently with the upper and lower granitoids. The lower granodiorite is characterized by mafic feeder dykes and larger mafic magmatic enclaves, whereas the enclaves occurring in the upper granite are comparatively smaller and the feeder dykes could not be traced here, except two late-stage mafic dykes. The mafic enclaves occurring in the upper granite show higher degrees of hybridization with respect to those occurring in the lower granite. Furthermore, enclaves are widely distributed in the upper granite, whereas enclaves in the lower granite occur adjacent to the main feeder dykes.Geochemical signatures confirm that the intermediate rocks occurring in the Nimchak pluton are mixing products formed due to the mixing of mafic and felsic magmas. A number of important physical properties of magmas like temperature, viscosity, glass transition temperature and fragility have been used in magma mixing models to evaluate the process of magma mixing. A geodynamic model of pluton construction and evolution is presented that shows episodic replenishments of mafic magma into the crystallizing felsic magma chamber from below. Data are consistent with a model whereby mafic magma ponded at the crust-mantle boundary and melted the overlying crust to form felsic (granitic) magma. The mafic magma episodically rose, injected and interacted with an overlying felsic magma chamber that was undergoing fractional crystallization forming hybrid intermediate rocks. The intrusion of mafic magma continued after complete solidification of the magma chamber as indicated by the presence of two late-stage mafic dykes.  相似文献   

北阿尔金地区古元古代ca.2.0Ga岩浆-变质事件   总被引：4，自引：3，他引：1  

朱文斌  葛荣峰  吴海林 《岩石学报》2018,34(4):1175-1190

中国有三个主要的克拉通,分别是华北、华南和塔里木,它们在显生宙经造山过程聚集到一起。塔里木克拉通位于中国的西北部,面积超过60万平方千米,其北侧为中亚造山带,南侧为西昆仑造山带和阿尔金造山带。塔里木克拉通的前寒武纪岩石主要出露在其南北两侧边缘,包括库鲁克塔格、敦煌、阿尔金、铁克里克和阿克苏地块,它们记录了塔里木克拉通早期的构造演化。北阿尔金地块的阿克塔什塔格地区位于塔里木克拉通的东南边缘。该地区最老的岩石被称为米兰群或阿克塔什塔格杂岩。主要岩石包括太古宙的TTG岩石和表壳岩,以及古元古代的片麻状花岗岩,另有少量变质基性岩呈包体状出露在强变形的长英质侵入体中。本文对该区闪长质片麻岩开展了锆石SHRIMP U-Pb定年,同时还对变质基性岩进行了锆石LA-ICP-MS U-Pb测年和地球化学分析,目的是要约束北阿尔金地区古元古代的岩浆-变质事件。闪长质片麻岩的结晶年龄为2.04～2.03Ga,它们形成于岛弧环境。地球化学分析表明,变质基性岩的原岩是拉斑玄武岩。它们有类似于E-MORB的平坦的稀土配分模式,Nb、Ta、Zr、Hf不亏损,说明它们形成于大洋板内环境。在变质基性岩中还识别出两期变质锆石,其中2.05～2.01Ga的早期锆石代表了麻粒岩相的变质作用,而1.98～1.96Ga的晚期锆石可能与角闪岩相的退变质作用有关。无论该区岩浆作用还是变质作用都与约2.0Ga发生的俯冲增生造山事件有关。  相似文献   

Juxtaposition of Barrovian and migmatite domains in the Chinese Altai: a result of crustal thickening followed by doming of partially molten lower crust   总被引：1，自引：0，他引：1       下载免费PDF全文

Y. D. Jiang  P. Štípská  M. Sun  K. Schulmann  J. Zhang  Q. H. Wu  X. P. Long  C. Yuan  M. Racek  G. C. Zhao  W. J. Xiao 《Journal of Metamorphic Geology》2015,33(1):45-70

Ordovician metasedimentary rocks are the oldest and most extensive sedimentary sequence in the Chinese Altai. They experienced two major episodes of deformation (D1 and D2) resulting in the formation of juxtaposed Barrovian‐type and migmatite domains. D1 is characterized by a penetrative sub‐horizontal fabric (S1), and D2 is marked by upright folds (F2) with NW–SE‐trending axial planes in shallow crustal levels and by sub‐vertical transposition foliations (S2) in the high‐grade cores of large‐scale F2 antiforms. In the Barrovian‐type domain, successive growth of biotite, garnet and staurolite is observed in the S1 fabric. Kyanite included in garnet and plagioclase in the migmatite domain is interpreted to have formed also in S1. In the biotite and garnet zones, the spaced S2 cleavage is marked by biotite and muscovite, and in the staurolite and kyanite zones, the penetrative S2 fabric is characterized by sillimanite, locally with late cordierite. Phase equilibria modelling indicates that the S1 fabric was associated with an increase in pressure and temperature under Barrovian‐type conditions in both domains. The S2 fabric was related to decompression, in which rocks in the biotite and garnet zones well preserve the peak assemblage, and the higher grade rocks in the staurolite and kyanite zones re‐equilibrated to different degrees under high‐temperature/low‐pressure (HT/LP) conditions. The D1 metamorphic history is attributed to the progressive burial related to Early–Middle Palaeozoic crustal thickening and the metamorphism associated with D2 is interpreted to result from exhumation by vertical extrusion. The extrusion of hot rocks was contemporaneous with the formation of gneiss domes accompanied by the intrusion of juvenile magmas at middle crustal levels during the Middle Palaeozoic. Consequently, there is a genetic link between the Barrovian‐type and migmatite domains related to continuous transition of the Barrovian‐type fabric into the HT/LP one during development of domal structures in the southern Altai orogenic belt. This study has a broad impact on the understanding of the thermo‐mechanical behaviour of accretionary orogenic systems worldwide. The lower crustal flow and doming of hot crust, so far reported only in continental collisional settings, seems to be also an integral mechanism responsible for both horizontal and vertical redistribution of accreted material prior to continental collision.  相似文献   

大兴安岭北段扎兰屯哈多河“花岗质糜棱片麻岩”年代学及地球化学特征研究   总被引：2，自引：0，他引：2  

高峰  郑常青  姚文贵  李娟  施璐  崔芳华  高源  张行行 《地质学报》2013,87(9):1277-1292

哈多河“花岗质糜棱片麻岩”为一套变质变形的花岗质岩石,其岩石组合为细粒黑云母二长花岗质糜棱片麻岩、细粒黑云母花岗质糜棱片麻岩和细粒石榴二云母花岗质糜棱片麻岩.SiO2含量在66.4％～74.52％之间,K2O+ Na2O介于7.36％～8.84％之间,Al2()3含量在13.43％～15.74％之间,A/CNK =0.974～1.092,属于高钾钙碱性、准铝质到过铝质岩石;具有较高的稀土总量(ΣREE=94.15×10-6～164.30×10-6),稀土元素配分模式表现为轻稀土元素(LREE)富集、重稀土元素(HREE)相对亏损的右倾型曲线,具有弱的负铕异常;富集Rb、Ba、U、K等大离子亲石元素,相对亏损Ta、Nb、P、Ti等元素.锆石U-Pb测年结果表明,哈多河“花岗质糜棱片麻岩”的岩浆侵入期次可分为两期,第一期在320Ma左右,代表性岩石为细粒黑云母花岗质糜棱片麻岩和细粒石榴二云母花岗质糜棱片麻岩;第二期在304Ma左右,代表性岩石为细粒黑云母二长花岗质糜棱片麻岩.综合岩相学、年代学及岩石地球化学特征,哈多河“花岗质糜棱片麻岩”原岩为高钾钙碱性Ⅰ型花岗岩,形成于晚石炭世兴安地块与松嫩地块的后碰撞构造环境下,之后在早二叠世末遭受“后碰撞作用”的影响,发生较强的韧脆性变质变形.  相似文献