山西省代县羊延寺—张山沟直闪岩矿床特征及其成因浅析

山西省代县羊延寺-张山沟直闪岩矿床产于五台系石咀群金刚库组变质岩中。直闪岩矿体呈带状延长，由十几个矿体组成，可分为含硅灰石直闪岩和含石榴子石直闪岩两种岩材类型。由于其独特的矿物组合特征和结构构造特征，以及良好的岩石物理性质，使之成为品种独特、技术加工性能较好的饰面材料。通过区域地质及岩石化学认为，直闪岩系古老夕卡岩经后期变质作用而成。     

新矿物等轴铂铜矿的发现及其命名问题

Isoplatinocopper,a new mineral,has been found in a bistagite-pyroxene amplhibolite intrusive in the Yenshan Region,China,This mineral has been identified to be isometric and pale yellowish-white in color with a molecular formula of Pt4Cu5,α0=3.786A,specifie gravity=14.5,and no magnetism.In reflected light it is essentially isotropic,and yellowish-white in eclor with reflective power being 58% for green light,61% for yellow and 61.5% for red respectively,and its microhardness 127-220kg/mm^2.On the ground of the data on their chemical composition and crystal structure,Pt-Fe-Cu and Pt-Cu platinum minerals are divisible into two types,i.e.tulameenite which includes those with a composition of Pt5Fe4Cu-Pt2Fe3Ci2 and Pt2FeCu,and isoplatinocopper which possesses a composition of Pt4Cu4-Pt4Cu5.5     

Petrology, chronology and isotope geochemistry of the proterozoic amphibolites from Xiangshan, central Jiangxi province, China

On the basis of a comprehensive study on the petrology,trace elements and isotopic geochemistry of the Xiangshan amphibolites,we suggest that the protoliths of the amphibolites were basalts formed in an island-arc tectonic setting.The basaltic magma was derived from a slightly depleted mantle source with a small amount of crustal contamination.Assemblage of the rock-froming minerals indicates that these amphibolites underwent a low-grade metamorphism of amphibolite facies.According to the formation age(1113Ma) and subsequent metamophic age(726.6Ma) of the basalts aw well as the geological and gochemical features of these amphibolites,a tectonic model of Proterozoic oceanic island-arc setting is proposed for central Jiangxi.     

Geochemical Characteristics and LA-ICP-MS Zircon U-Pb Dating of Amphibolites in the Songshugou Ophiolite in the Eastern Qinling

Geochemical studies on the arnphibolites in the Songshugou ophiolite from Shangnan County, Shaanxi Province demonstrate that the protolith of the amphibolites is tholeiitic. The arnphibolites can be classified into two groups according to their REE patterns and trace element features. Rocks of the first group are depleted in LREE while rocks of the second group are slightly depleted in LREE or flat from LREE to HREE without significant Eu anomaly. The first group of rocks have (La/Yb)N=0.33-0.55, (La/Sm)N= 0.45-0.65, and their La/Nb, Ce/Zr, Zr/Nb, Zr/Y and Ti/Y ratios are averaged at 1.20, 0.12, 31.02, 2.92 and 198, respectively, close to those of typical N-MORB. The second group of rocks have (La/Yb)N=0.63-0.95, (La/ Sm)N = 0.69--0.90, and their average La/Nb, Ce/Zr, Zr/Nb, Zr/Y and Ti/Y ratios are 0.82, 0.83, 1.15, 0.16, 19.00, 2.58 and 225, respectively, which lie between those of typical N-MORB and E-MORB but closer to the former. The two groups of rocks both exhibit flat patterns from Th to Yb in th     

Geochemistry of the Shushui Complex,South Shanxi Province,China

The Shushui Complex can be divided into three rock units based on field investigation, petrography and geochemistry:(1) felsic gneisses, (2) supracrustal rocks consisting of amphibolite, marble and quartzite, and (3) late granites. Of the complex, felsic gneisses are dominant and formed in the Late Archaean, which were intruded by a basic dyke with a whole-rock Rb-Sr isochron age of 2264±219 Ma. The data on rare-earth elements as well as on major and trace elements presented for most of the rock types making up the complex suggest that (1) basic gneisses were produced by partial melting of mantle peridotite, followed by fractional crystallization, and (2) felsic gneisses produced by varying degree of melting of a mafic source. The most suitable tectonic setting to account for the generation of both types would be similar to the underplate setting.     

REE Characteristics and Petrogenesis of Amphibolites in the Dabie Complex

Based on their REE features, stratoid or lenticular amphibolites in the Dabie Complex are di-vided into two types:one is characterized by flat REE distribution patterns and the other by LREE-enrichment. Results of the REE quantitative modeling suggest that the amphibolites were formed from 20% partial melting of garnet lherzolite and 35-56% fractional crystallization of olivine(type TH1) or 14-20% fractional crystallization of olivine and clinopyroxene(type TH2).     

Petrochemical Comparison of 3.5 Ga Old Mafic Amphibolite Inclusions from Eastern Hebei Province with Archean Mafic—ultramafic Supracrustals of Uncertain Antiquity,Southern Jilin Eastern Liaoning Prov

New major element data for coexisting minerals and bulk-rock REE analyses,combined with previously obtained petrologic/geologic information,allow comparison of Archean mafic-ultramafic meta-igneous rocks from adjacent portions of northeastern Sino-Korean shield .Isotope data published by previous workers document an Early Archean age of formation for metabasaltic rocks now occurring as mafic amphibolite inclusions in tonalitic gneisses west of Bohai Bay(area).Mafic-ultramafic mineral assemblages developed in tonalitic gneisses west of Bohai Bay(areaA).Mafic-ultramafic mineral assemblages developed in amphibolite facies Archean supracrustals east of Bohai Bay(areaB)are chemically similar ,but pre-existing phase associations have been overprinted by the effects of several later metamorphic events.Non0peridotitic area B protoliths appear to be more magnesian ,averaging-12wt.%MgO(versus-7wt.%for area A),and are slightly less fractionated in REE concentrations relative to chondrites(La-Lu=30-8X versus 37-14X for area A),thus perhaps being more mantle-like than area A metabasaltic analogues.The basaltic-komatiitic series east of Bohai Bay probably represents the most ancient crust of that region,being invaded by Archean tonalities,which were subsequently converted to orthogneisses.These observations are compatible with the hypothesis that ,similar to area A metabasaltic rocks now found as amphibolitic inclusions in orthogneisses,are B mafic supracrustals were formed during Early of Middle Archean time ,prior to widespread isofacial amphibolite facies metamorphism(600-700℃,5-7kb,low αH2O).     

东疆哈尔里克造山带中角闪石的特征及其地质意义

东疆哈尔里克造山带中角闪石的特征及其地质意义＠赵明＠王赐银￥南京大学地球科学系哈尔里,克造山,带角闪,石角闪岩,相温压条件东疆哈尔里克造山带中角闪石的特征及其地质意义赵明王赐银（南京大学地球科学系,南京２１００９３）关键词哈尔里克造山带角闪石角闪岩相温压...