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Structure Refinement of Cs-rich Na-Li Beryl and Analysis of Its Typomorphic Characteristics of Configurations

Acta Geologica Sinica(English Edition) 2007年第1期81卷 61-67页

作者： LIU Yan DENG Jun LI Guowu shi guanghai State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences Beijing 100083 Key Laboratory of Lithosphere Tectonics and Lithoprobing Technology of the Ministry of Education China University of Geosciences Beijing 100083 Laboratory of Single-Crystal X-Ray Diffraction China University of Geosciences Beijing 100083

The tabular beryl found in Huya Country, Sichuan Province is a rare and special member among beryls. Chemical analysis reveals that the beryl is a new type of Cs-rich Na-Li beryl, and the content of alkalis （Li20, Na2O, K2O, Rb2O, Cs2O） is up to 2.41%. The CCD system on the SMART APEX four circle single crystal diffractometer was used in this experiment to determine the structure of the sample accurately. The beryl belongs to the hexagonal system; its space group is P6/mcc. The dimensions of the unit cell are as follows： a = 0.91961（3） nm, c = 0.91969（7） nm, c/a = 1.0000, V= 0.67357 nm3, 7 = 120°, α= 90°, β = 90°. The accurate atomic coordinates of alkali metal ions and other crystallographic parameters are also obtained： Z = 2, the calculated density D = 2.754 g/cm^3 and final R （ I 〉 2 σ （/3）= 0.046 for 5597 reflections. The crystal structure was described by coordination polyhedron. Based on the data gained, a three-dimensional graph of the crystal structure of tabular beryl was made with the ATOMS 6.0 software. The refinement of crystal structure indicates that there are two main reasons for the cause of the tabular configuration：（1） The substitution of Be by Li into the tetrahedral framework weakened the stacked six-sided rings [Si6O18]^12- of the tetrahedral Si; （2） Alkalis （mainly Na and Cs） are too large to substitute in four-fold or six-fold coordination within the structure and are accommodated in the vacant channel. The accommodation of these alkalis strengthened the structure of six-sided rings of the tetrahedral Si. And other alkali metal ions and free volatile molecules such as H2O and CO2 occupy variable positions in the channel. The equation of the electrovalence is Li＋＋Na＋→Be^2＋. According to structural and compositional differences, the monoclinic crystal of tabular beryl is considered to be a new member of the beryl group. Chemical constraints of the environment, namely, the bulk-rock chemistry and the fluid-phase composition and physical-chemica

关键词： beryl crystal structure tabular crystal typomorphic characteristics

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The fluid inclusions in jadeitite from Pharkant area, Myanmar

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Chinese Science Bulletin 2000年第20期45卷 1896-1901,1923页

作者： shi guanghai CUI Wenyuan WANG Changqiu ZHANG Wenhuai Department of Geology Peking UniversityBeijing 100871China Institute of Resource China University of GeosciencesWuhan 430074China

A lot of liquid-gas and liquid-gas-solid inclusions were found in Pharkant jadeitites, northwestern Myanmar and their characteristics, geological setting and porphyroclastic jadeites with inclusions in them were described in detail. The results analyzed by Raman spectrometer showed that the component of liquid-gas phase and solid phase (daughter minerals) in fluid inclusions is H2O + CH4 and jadeite separately. The results indicated that Pharkant jadeitites were crystallized from H2O + CH4 bearing jadeitic melt which may originate from mantle. The P-T conditions in which the jadeitites were crystallized were speculated to be T>650℃, P>1.5 GPa.

关键词： Pharkant Myanmar jadeitite jadeite fluid inclusion H2O + CH4 jadeitic melt mantle.

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Timing of Anatexis within the Berere HTHP Complex Belt of Maevatanana Area,North-Central Madgascar,and its Geological Significance

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Acta Geologica Sinica(English Edition) 2020年第5期94卷 1393-1409页

作者： LI Peng LIU Shanbao LI Jiankang shi guanghai LIU Xiang MNR Key Laboratory of Metallogeny and Mineral Assessment Institute of Mineral ResourcesChinese Academy of Geological SciencesBeijing 100037China State Key Laboratory of Geological Processes and Mineral Resources China University of GeosciencesBeijing 100083China Hunan Nuclear Geology Changsha 410011China

The Berere HTHP Complex belt in Maevatanana area of north–central Madagascar formed in the^2.5 Ga orogeny and underwent high temperature(up to 1050℃)and high pressure(up to 11.5 kbar)granulite facies *** a widespread anatexis took place and numerous widely distributed felsic leucosomes *** majority of these leucosomes are parallel to the schistosity of the complex or are present as stockworks,as thin layers,or as lenses at different scales in the host ***,we report new petrographic data,zircon LA-ICP-MS U-Pb ages,and Lu–Hf isotopic data for felsic leucosomes within this ***,as identified by the petrological study of felsic leucosomes in the field and in thin sections,involved initial ternary feldspar exsolving to produce antiperthite and a quartz+plagioclase±K-feldspar+sericite mineral assemblage around feldspar grain *** is apparent along muscovite grain boundaries,and residual sericite is present around the margins of feldspar and quartz,all suggesting that anatexis was driven by reactions involving *** U–Pb dating indicates that the felsic leucosomes within the complex formed at 2467–2369 *** majority of samples have positiveεHf(t)values,although a few have negative values,suggesting their formation from magmas predominantly sourced from the depleted mantle,possibly with the involvement of minor amounts of crustal ***-stage Hf model ages andεHf(t)values for these samples are consistent with those for gneisses of the basement,indicating that the felsic leucosomes were formed by the anatexis of gneisses and both of their protolith formed during the formation of continental crust in Meso-Neoarchean(ca.3.1–2.7 Ga).As such,the crystallization age of the felsic leucosome(~2.4 Ga)represents the timing of regional anatexis and a change to post-orogenic *** this anatexis is also corresponds to the thermal event in Dharwar craton in India which has a pronounced similar Precambri

关键词： anatexis felsic leucosome U-Pb zircon dating Lu-Hf isotope Madagascar

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Origin and Geological Significance of TTG Gneisses from the Maevatanana Greenstone Belt in North-Central Madagascar,and A Comparison with India

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Acta Geologica Sinica(English Edition) 2017年第3期91卷 1003-1024页

作者： LI Peng LI Jiankang LIU Shanbao PEI Rongfu shi guanghai Key Laboratory of Metallogeny and Mineral Resource Assessment Institute of Mineral ResourcesChinese Academy of Geological Sciences State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences

The Maevatanana greenstone belt in north-central Madagascar contains widespread exposures of tonalite-trondhjemite-granodiorite （TTG） gneisses, and is important for its concentrations of various metal deposits （e.g., chromium, niekle, iron, gold）. In this paper we report on the petrography, and major and trace element compositions of the TTG gneisses within the Berere Complex of the Maevatanana area, as well as LA-ICP-MS U-Pb ages and Lu-Hf isotopic compositions of zircons from the gneisses. The gneisses consist mainly of granitoid gneiss and biotite （± hornblende） plagiogneiss, and analysis of thin sections provides evidence of crushing, recrystallization, and metasomatism related to dynamic metamorphism. Samples have large variations in their major and trace element contents, with SiO2 = 55.87-68.06 wt%, Al2O3 = 13.9-17.8 wt%, and Na2O/K2O= 0.97-2.13. Geochemically, the granitoid gneisses and biotite plagiogneisses fall on a low-Al trondhjemite to granodiorite trend, while the biotite-hornblende plagiogneisses represent a high-Al tonalite TTG assemblage. Zircon U-Pb dating shows that the Berere Complex TTG gneisses formed at 2.5-2.4 Ga. Most εHf（t） values of zircons from the biotite （q- hornblende） plagiogneisses are positive, while most εHf（t） values from the granitoid gneisses are negative, suggesting a degree of crustal contamination. Two-stage Hf model ages suggest that the age of the protolith of the TTG gneisses was ca. 3.4-2.6 Ga, representing a period of paleocontinent formation in the Mesoarchean. Geothermometries indicate the temperature of metamorphism of the TTG gneisses was 522-612℃. Based on these data, the protolith of the TTG gneisses is inferred to have formed during the development of a Mesoarchean paleocontinent that is now widely exposed as a TTG gneiss belt （mostly lower amphibolite facies） in the Maevatanana area, and which records a geological evolution related to the subduction of an ancient oceanic crust and the collision of microcontinent

关键词： TTG gneiss petrology geochronology Maevatanana greenstone belt Madagascar India

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Paleomagnetic data from Early Cretaceous volcanic rocks of West Liaoning:Evidence for intracontinental rotation

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Chinese Science Bulletin 2002年第21期47卷 1832-1837页

作者： ZHU Rixiang SHAO Ji’an PAN Yongxin shi Ruiping shi guanghai LI Darning Institute of Geology and Geophysics Chinese Academy of SciencesBeijing 100101China Department of Geology Peking UniversityBeijing 100871China Institute of Geology China Seismological BureauBeijing 100029China

Detailed rock magnetic studies of 55 lavas from Yixian and Fuxin area, West Liaoning, show the primary carriers of remanence to be pseudo-single domain ti-tanomagnetite. K/Ar dating indicates that the volcanic sequence spans 93 to 133 Ma. Stepwise thermal demagnetization successfully isolated well-defined characteristic magnetization (ChRM) in all lavas thermal-treated above 250℃ The mean paleodirections are D/I=5.9°/58.8° (α95 = 2.9°) and D/I =179.2°/-59.9° (α95 = 5.2°) for 27 normally magnetized flows and 28 reversibly magnetized flows, respectively. It indicates that since the Early Cretaceous there is no significant horizontal movement and rotation between the Yixian-Fuxin area and Eurasia. However, Korea Peninsula may have undergone a clockwise rotation of 33.9° relative to the Yixian-Fuxin area during the Cretaceous. On the basis of characteristics of hotspot origins (core-mantle boundary or upper mantle), the clockwise rotation of Korea Peninsula relative to Eurasia is assumed to be

关键词： Cretaceous paleomagnetism geodynamics.

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REE composition in scheelite and scheelite Sm-Nd dating for the Xuebaoding W-Sn-Be deposit in Sichuan

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Chinese Science Bulletin 2007年第18期52卷 2543-2550页

作者： LIU Yan DENG Jun LI ChaoFeng shi guanghai ZHENG AiLi State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences Beijing 100083 China Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China

The scheelite with large size and euhedral shape from Xuebaoding, Sichuan Province is an ideal min- eral to study REE patterns and Sm-Nd dating of non-gold deposits. The scheelite has diameters of 1― 10 cm and colors of pale beige to deep orange. Most of these scheelites occur in association with beryl, cassiterite and muscovite. The rare earth elements indicate that scheelite samples from Xuebaoding W-Sn-Be deposits contain high concentrations of rare earth elements with total ΣREE+Y contents in the range of 369―1725 μg·g?1 and nearly all of these scheelite samples are enriched in LREE and depleted in HREE and have negative Eu anomalies. The REE patterns of the scheelites are similar to those of A-type granite with obvious tetrad effect, similar to that of type II scheelites. Based on reported fluid inclusion studies, the mineralizing-fluid of the Xuebaoding W-Sn-Be deposit indicates low Na activity. The REE patterns of the scheelite are probably controlled by partition coefficient in hydrothermal fluid. In the 147Sm/144Nd-143Nd/144Nd diagram, the scheelites show a linear array corresponding to an isochron age of 182.0±9.2 Ma (MSWD = 0.52). The Sm-Nd age represents the formation age of the scheelite and can indicate that the W, Sn and Be mineralization at Xuebaoding took place in the Early Yanshanian. The Sm-Nd dating result is important for the study of the multi-metal resources in western Sichuan Province.

关键词：白钨矿钐-钕同位素测年四川钨-锡-铍沉积物

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Formation of a Hydrothermal Kaolinite Deposit from Rhyolitic Tuff in Jiangxi, China

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Journal of Earth Science 2014年第3期25卷 495-505页

作者： Ye Yuan guanghai shi Mengchu Yang Yinuo Wu Zhaochong Zhang Anjie Huang Jiajing Zhang State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences Geological Survey of Jiangxi Province Northeast Geological department of Jiangxi Geological Exploration Bureau

The Longmen kaolinite deposit is one of the largest hydrothermal clay deposits of Ganxi volcanic basin（northern Wuyi Mountain area, China）. The pristine host rocks are rhyolitic crystal-vitric tuff and minor lapilli tuff from the Late Jurassic Ehuling Formation. The ore consists of kaolin-group minerals（kaolinite, dickite）, pyrophyllite with minor quartz, sericite, pyrite, etc.. From the host rocks to the transition zones（altered rocks） then to the vein ores, contents of SiO2 and TFe2O3 decrease, whereas Al2O3 and LOI increase, consistent with the contents increase of kaolin minerals and pyrophyllite in the samples. The total REE abundances of the ores are much lower than that of the host and altered rocks, Rb, Nb, Nd, Zr, Ti and Y are significantly depleted. Apparent zoning features of bulk geochemistry and mineral component reflect that the kaolinite deposit occurred at the expense of the host rock by ascending hydrothermal fluids with distinct removal of SiO2, TFe2O3, Na2O, K2O. According to the mineral assemblage, the formation temperature of this deposit falls within the range of 270–350 ℃. With regard to the industrial applications, the kaolinized ores are suitable for use in ceramics and gemologic materials crafted for seal stones. Moreover, in mineralogical terms, this deposit is also proved to be an excellent example for studying channeled hydrothermal alterations of rhyolitic tuff.

关键词： China geochemistry hydrothermal alteration Jiangxi kaolinite pyrophyllite.

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The Tashisayi nephrite deposit from South Altyn Tagh, Xinjiang,northwest China

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Geoscience Frontiers 2019年第4期10卷 1597-1612页

作者： Kong Gao guanghai shi Meili Wang Gen Xie Jian Wang Xiaochong Zhang Ting Fang Weiyan Lei Yan Liu State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences (Beijing)Beijing 100083China No.11 Gold Geological Party of the CAPF Lasa 850000China School of Earth and Ocean Sciences Cardiff UniversityCardiffCF10 3ATUK School of Civil and Resource Engineering University of Science and Technology BeijingBeijing 100083China School of Resources and Materials Northeastern University at Qinhuangdao BranchQinhuangdao 066004China Institute of Geology Chinese Academy of Geological SciencesBeijing 100037China

The Tashisayi nephrite deposit is located in South Altyn *** Qiemo County,Xinjiang Province,northwest *** is a recent discovery in the vast,well-known Kunlun-Altyn nephrite belt distributed along the south of the Tarim Basin,producing more than half of the nephrite from the whole belt in *** investigations revealed that it is a dolomitic marble-related(D-type)nephrite deposit,but little is known about its age of formation and relationships between the granites and *** we report field investigations,petrography of the neph rite,as well as petrography,geochemistry,geochronology of the zoisite-quartz altered intrusive rock and adjacent *** A-type granite is identified with a SHRIMP U-Pb zircon age of 926±7 Ma,suggesting it was emplaced in an extensional tectonic environment at that *** altered intrusive rock has a cluster of U-Pb zircon age of 433±10 *** similar trace element features to the A-type granite,suggesting it was formed in an extensional regime at this later *** formed because of the metasomatism of dolomite marble by hydrothermal *** is inferred that Ca^2+was released from the dolomitic marble by metasomatism forming Ca-rich fluids,which caused alteration of both the intrusive rocks(6.00-8.22 wt.%CaO)and granite(1.76-3.68 wt.%CaO)near the nephrite ore *** is also inferred that Fe^2+from the granite migrated towards the dolomite *** fluids gave rise to the formation of *** as zoisite,in the nephrite and altered intrusive rock,and epidote in the *** on the contact *** in hydrothermal processes,and consumption of Ca^2+,the Tashisayi nephrite is considered to have formed at the same time as the alteration of the intrusive rocks,i.e.~433 *** geochronological similarity(~926 Ma.433 Ma)of South Altyn and North Qaidam may suggest that tectonically they belong to one single complex in the past,which was offset by the Altyn Tagh fault(ATF).The similar

关键词： Nephrite Dolomite marble A-type granite Altyn Tagh fault Zircon U-Pb dating

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北祁连川刺沟A型花岗岩的年代学及其意义

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岩石学报 2018年第6期34卷 1657-1668页

作者：王建谢亘施光海王妍中国地质大学地质过程与矿产资源国家重点实验室北京100083 武警黄金部队第十一支队拉萨850000

关于北祁连南蛇绿岩带蛇绿岩,前人多认为是形成于早古生代洋中脊的大洋岩石圈残片。本次对川刺沟A型花岗岩和其周围超基性岩的研究,有助于较全面认识该区时代序列与构造格架。川刺沟A型花岗岩的组成矿物为碱性长石(～45%)、石英(～30%)... 详细信息

关于北祁连南蛇绿岩带蛇绿岩,前人多认为是形成于早古生代洋中脊的大洋岩石圈残片。本次对川刺沟A型花岗岩和其周围超基性岩的研究,有助于较全面认识该区时代序列与构造格架。川刺沟A型花岗岩的组成矿物为碱性长石(～45%)、石英(～30%)、斜长石(～15%)以及少量的霓辉石(～5%)等,发育条纹和显微文象等结构。岩石具有高SiO_2(72.58%～73.96%)和高Na_2O+K_2O(10.12%～10.39%),A/NK<1,10000Ga/Al值为2.59～3.49。微量元素型式显示该花岗岩富集Rb、Ba、Th、K,强烈亏损Sr、P、Ti、Nb、Ta,稀土元素型式呈明显负铕异常(δEu=0.56～0.60)的海鸥形。岩相学和地球化学特点均符合A型花岗岩特征,进一步细分可将其归属于A_2型,形成于后造山环境。其周围的超基性岩稀土型式呈"U"型,富集Th、Zr、Hf,推测其经历过俯冲熔/流体交代。SHRIMP锆石U-Pb定年给出一组该A型花岗岩的谐和年龄501±5Ma,可以代表其侵位年龄。该年龄早于北祁连造山带陆-陆碰撞时间,晚于大陆裂谷发生时间。由于A_2型花岗岩后造山环境有两亚类:陆-陆碰撞后造山和活动大陆边缘拉张环境,本次研究结果更加倾向后者,即,该A型花岗岩为在中-晚寒武世俯冲作用影响下,活动大陆边缘弧前发生拉张,软流圈部分熔融产生幔源岩浆底侵形成。进一步推测该地区超基性岩可能与俯冲有关,为非经典定义的蛇绿岩。

关键词：北祁连早古生代 A型花岗岩 SHRIMP锆石测年活动大陆边缘蛇绿岩

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缅甸硬玉岩区的硬玉化绿辉石岩

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岩石学报 2006年第4期22卷 971-976页

作者：易晓施光海何明跃中国地质大学(北京) 北京100083

绿辉石岩是缅甸硬玉岩区一种新的岩石类型,普遍遭受多期次硬玉化。未发生硬玉化的绿辉石含较高TFeO和CaO,但较低的MgO,按化学成分分类部分已属霓石-普通辉石系列的中间相。这种绿辉石很可能是硬玉质的流体/熔体交代地幔辉石岩类的产物,... 详细信息

绿辉石岩是缅甸硬玉岩区一种新的岩石类型,普遍遭受多期次硬玉化。未发生硬玉化的绿辉石含较高TFeO和CaO,但较低的MgO,按化学成分分类部分已属霓石-普通辉石系列的中间相。这种绿辉石很可能是硬玉质的流体/熔体交代地幔辉石岩类的产物,与主期大规模硬玉岩的结晶、钠质-钠钙质角闪石边和钠铬辉石的形成同期或稍后,是该区第Ⅰ期的硬玉化。沿绿辉石的解理或裂隙交代并伴有充填的硬玉是在相对拉张的构造背景下形成的,是该区第Ⅱ期的硬玉化。切割早期绿辉石和硬玉的充填硬玉细脉可能是最晚一期的硬玉化。硬玉化绿辉石岩的结构与显微构造特征指示了在缅甸硬玉岩区,至少存在不少于3期的硬玉化的交代充填作用。文中讨论了硬玉化物质的可能来源,认为其可能与俯冲板片上的沉积物有密切关系。

关键词：绿辉石绿辉石岩硬玉交代作用多期次矿化缅甸

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