Abstract:Charmockites exposed inMashikou area,northwestern Hebei,intruded into tonalitic gneisses and assume lenticular and elliptical forms.Charnockites have low K2O,CaO,TiO2,high Al2O3,Na2O,rich LREE,depleted HREE,and strongly fractionated patterms.K/Rb ratios range from 500 to1000.These Chemical characteris are similar to those of typical Archean gray gneisses in the world. U-Pb single zircon isotope ages of the charmockites have been obtained.The coarse charmockites with block structure have ages of 2462±1Ma(Z9143B)and 2477+85-77Ma(Z9146),suggesting that charmockites were formed in the period of 2477—2461Ma.The fine-grained charmockite with gneissosity has an age of 2272+68-52.As the sample underwent multi-episodic Pb loss,the age has no clear geological implication.

Abstract:Widely distributed in the Zhenyuan gold deposits and closely related to gold mineralization in time and space,lamprophyres underwent different degrees of alteration and partly experienced mineralization.According to degrees of alteration and mineralization,lamprophyres in the orefield might be divided into fresh (Weakly altered),altered and mineralized ones.According to calculations by the mass balance equation for element activity regularity in tye process of lamprophyic alteration and mineralization,it is shown that fluids responsible for lamprophyric alteration were Si ,Al rich alkaline fluids containing transitional,lthophile,volatile and chalcophile(or ore forming)elements.These fluids are considered to have been products of crystallization of lamprophyric magma.The fluibs responsible for lamprophyric mineralization were enriched in such components as K2O,CaO,CO 2,F,Cl,S,As,Sb,Au,and Ag,thus exhibiting multi source character.

Abstract:This paper reports Pb, Sr, Nd, isotopic compositions of 8 granitoid plutons from Ningshan,South Qinling, which were all formed about 200 Ma B.P. The results indicate that the granitic rocks from these plutons are characterized by low radiogenic Pb isotopic composition. Initial (87 Sr/86Sr)tratios range from 0.70495 to 0.70908,εNd(t) values from -2.41 to -8.55, and Nd isotopic model ages (TDM) from 1.20 Ga to 1.71 Ga. From east to west,εNd(t) values gradually increase, whereas TDMvalues gradually decrease. This study reveals that the magmatic source of the Ningshan plutons was derived from the deep crust. In the magmatic source, basic magmatic material in the crust similar to Yaolinghe Group basic volcanic rocks (Pt3) in South Qinling is the major source for the formation of granitoids with less significant old continental crust material (Ar-Pt1). However, the proportion of the old continental crustal material in magmatic source increases from east to west. It is suggested that the deep crust of the Fuping Dome is mainly com- posed of Late Proterozoic basic magmatic material (Pt3) that was underplated beneath the Fuping Group (Pt1), but the old continental crustal material in the deep crust gradually increases from east to west in the Fuping Done. This indicates that the deep crust material displays east-west zoning and south-north structure, which is different from the ring distribution of surface-crust material of the Fuping Dome.

Abstract:The petrogenesis of eclogites scattered in gneisses on the northwestern margin of the Southern Shandong-Northern Jiangsu tectonic melange zone has been studied in this paper by petrological, mineralogical and petrochemical methods. Through our study, we have reached the conclusion that the protolith of eclogite is tholeiite formed in an island-arc environment. Geothermometry and geobarometry show that theP-Tconditions for the formation of eclogites areT788.35℃andP2.5 GPa. The formation of the eclogites is related to the subduction-collision orogeny between the North China and the Yangtze plate.

Abstract:During the field work in the Jinling skarn iron deposit of Shandong Province, the authors discovered a Al-rich alkali metasomatite composed of spinel-corundum-alkali feldspar in Jinling complex on the southwestern slope of Huashan Mountain. Jinling rock body is a slightly basic-intermediate-intermediate (slightly alkaline) complex affected by late alkali metasomatite, which might be divided into gabbro diorite, biotite (amphibole) diorites, syenopegmatite and aplite dikes. In the rock body there are commonly lots of wall rock xenoliths of various sizes such as siliceous rocks with chert stripes and argillaceous hornfels,and the spinel-corundum-alkali feldspar metasomatite occurs just in the xenoliths. Being light white or dark grey in color, the metasomatite assumes massive form with local taxitic structure, and is composed of corundum (10%—25%), spinel (belonging chemically to ceylonite, (3%—7%), and anorthoclase (40%—55%) as well as small amounts of muscovite magnetite, rutile and zircon. Being genetically obviously different from complex corundum formed by metamorphism of clay deposit, it might be a metasomatic product formed through reaction between pegmatite fluids rich in late alkaline volatile components (Na2O+K2O) and xenoliths of Carboriferous strata (claystone, clayey shale or clayey hornfels) within the complex body.

Abstract:Parnauite was first discovered in the United States in 1978. In China, it was first found in the Debao ore district of Guangxi in 1984. There are two forms of parnauite in Debao: foliated and fibrous. Chemical compositionof the foliated parnauite is given as follows (in percentage): CuO 56. 09, As2O518. 39, Al2O30. 21, FeO 0. 40, SiO20. 56, SO35. 20, CO23. 83, H2O+14. 40, totally 99. 08, suggestingan ideal chemical formula of Cu9(AsO4)2(SO4) (CO3) (OH)8·6H2O, which is somewhat different from that of parnauite fromtheUnitedStates; nevertheless, the compositionof the fibrousparnauite issimilar to that of parnauite from the United States. The foliated parnauite is jade green to greyish in color, and transparent, glassy to pearly in luster.H=2,Dm=3. 33,Dc=3. 35, biaxial negative. Refractive indicesNp=1. 709,Nm=1. 732,Ng=1. 738; 2V=54. 63°. The strongest lines in X-ray diffraction pattern of the foliated parnauite are 14. 85 (100), 10. 45 (15), 7. 20 (10), 6. 46 (12),4. 55 (60), 4. 03 (20), 2. 867 (17), 2. 818 (10). Orthorhombic system, space groupP2122, cell dimensionsa=14. 92°A,b=14. 28°A,c=6. 02°A, calculated cell dimensionsa=15. 052 (18)°A,b=14. 320 (7)°A,c=6. 002 (6)°A,Z=2.

Abstract:Melting, crystallization and quenching experiments were made on certain typical basalts (including alkaline picriticbasalt, olivine tholeiite and high-alumina basalt) aswell as some andesites from Fujian, Jiangxi andHenan of China and columbretitic tephrite from Vesuvian volcano of Italy. Three forms of minerals, namely microcrystals, skeletal crystals and embryonic crystals were formed. The microcrystal minerals included tabular-prismatic plagioclase, hourglass clinopyroxene, granular-prismatic leucite and magnetite; the skeletalcrystals included hollow tabular-prismatic plagioclase,”工-shaped”olivine, herringbone enstenite and zonal magnetite; the microcrystals included spherulitic plagioclase, petal-like-spherulitic clinopyroxene,snowflake-branched magnetite. This paper has summarized morphological characteristics and compositional features of experimental crystallized minerals, calculated growth rates of minerals, analysed formation mechanism of skeletal crystal and embryonic crystal minerals, probed into mechanisms fororientated arrangement of skeletal crystal minerals plagioclase and olivine as well as growth of skeletal crystal dendrite of enstenite, dealt with the growing process of crystal whisker, described the relationship of the embryonic crystal form to grain of crystallization as well as that of the crystal form to crystallization temperature, growth rate, and viscosity and acidity of magmatic melt.

Abstract:Quartz is well spread in the deposit and can be divided into five minerogenetic periods. The color, grain size and crystal morphology of quartz can indicate the degree of mineralization.Quartz formed in different minerogenetic periods contains different chemical elements. The contents of Al, Cr, Li, Pb, As, Ca and Mg in quartz are positively related to mineralization. The cell parameters of quartz measured by X-ray powder diffraction are controlled by chemical compo- sitions, which have positive relationship with the content of Al in quartz. The crystallinities of quartz formed in the main mineralizing period are lower than those of quartz formed in nonmineralizing periods. The ratio of D1/D0in higher than 6. 00 and has CO2absorbing peaks in infrared spectroscopic diagrams of quartz, which can indicate mineralization. The electron paramagnetic resonance studies of quartz show that the higher the concentration of the O-(Al) center, the better the mineralization. The specific gravity of quartz decreases with the evolution of hydrothermal fluid.

Abstract:Sylvanite was formed at the late mineralization stage of the Beiling gold deposit and occurs in comby network quartz, associated with native gold. The mineral assemblage includes sylvanite-na tive tellurium-altaite-native gold-quartz and sylvanite-melonite-altaite-quartz. Native tellurium,melonite and altaite exist as inclusions in sylvanite. Sylvanite occurs in columnar, tabular and grained forms and assume polysynthetic twin with strong anisotropy and bireflectance.Hv50=216—219 kg/mm2. Chemical composition:Ag 10.58%—12.36%,Au 23.70%—24.51%, Te 61.67%—62.30%, with small amounts of As,Cu, Zn, Fe and Ni. Chemical formula is Ag Au1.0494—1.2691Te4.215—4.9182. The strongest X-ray diffraction lines are 3.054(85),2.153(31),and 1.984(18). Unit cell parameters:a0=8.9502°A,b0=4.4973°A,c0=14.7063°A andβ=145°58′. The ore deposit was formed at 115.2—161.8℃and lower sulfur fugacity. Hydrogen and oxygen isotopic studies show that ore-forming fluids came from meteoric water of low salinity.The gold deposit is considered to be of volcanic epithermal type.

Abstract:From the discovery of the first new mineral hsianghualite in 1958 to the end of 1995,74 new minerals found in China had been approved by IMA CNMMN. Among them, 2/3 were discovered after 1981. The discovery of new minerals in China has the following features:(1) With the development of analytical methods, the number of new minerals discovered per year increases gradually: from the end of 1950s to 1960s, only one new mineral was discovered every year on the average, whereas from 1980s till now, three new minerals were discovered averagely every year. (2) The structures of many new minerals have been determined. (3) Most of the new minerals are in the lower category, mainly in the monoclinic system, and perfect crystals are rare; hsianghualite has the most abundant crystal faces, whose ideal faces can reach 146. (4) Among those new minerals, silicates take the first place in number, followed by native elements, alloys, and then oxides. (5) The modes of occurrence of new minerals are varied, most of them occurring in oxidized zones of various deposits and deposits related to ma fic or ultramafic rock masses. There are a few new minerals occurring in skarn and placer deposits or even in cosmic dusts and meteorite.(6) The new minerals are characterized by wide but uneven distribution. Till now, new minerals have been discovered in 20 provinces or autonomous regions, especially in Hebei, Qinghai, Inner Mongolia and Henan. The number of new minerals found in North China is larger than that found in South Chine. (7) The number of discoverers of new minerals is in tens. The first discoverer of new mineral is Prof. Huang Yunhui, whereas Prof. Yu Zuxiang is the one who discovered the most numerous new minerals in China, totally disclosing 11 new minerals by himself or together with other experts. Most of the discoverers are members of the Chinese Academy of Geological Sciences, China University of Geosciences, and Institute of Geochemistry, Academia Sinica as well as other educational and scientific research institutions. The discovery of new minerals has promoted the development of mineralogy in China. Tens of discoverers were awardees of the National Natural Sciences Prize or the Science and Technology Progress Prize of the Ministry of Geology and Mineral Resources for the discovery and research results of new minerals in 1980s. More than 60 new mineals discovered in China were collected by the Geological Museum of China, with some of them exhibited in the Minerals and Rocks Exhibiting Room.