Abstract:Garnet glaucophane schist coexistent with Permian limestone, quartzite and muscovite schist was recognized below Permian (meta)basalts and altered gabbro in the vicinity of Pana Village within the southern central Lhasa terrain. The blueschist consists of corroded garnet and amphibole porphyroblasts situated in a matrix of finegrained muscovite, epidote, chlorite, biotite, albite, quartz, and accessory rutile, titanite and apatite. Mn and Mg contents of the corroded garnet enclosing aegirinerich clinopyroxene, rutile and quartz decrease and increase, respectively, from core to rim. Amphibole porphyroblasts grew in several stages, as evidenced by two different galucophane components in the cores and NaCa amphibole and/or Ca amphibole in the rims. The glaucophane surrounded by late glaucophane is richer in Fe and poorer in Na than the late one that is close to the pure glaucophane endmember. The Si contents of phengite are high in the center but low along the rim. The p-t path, starting above 2.5 GPa450℃ and showing subsequently first a temperature increase to 500℃ and then a pressure release via blueschist conditions to 0.6 GPa, was reconstructed using a p-t pseudosection calculated for the p-t range 0.4~2.8 GPa and 250~650℃. Such a low gradient is typical for the subduction of a cold oceanic plate along a continental margin. In combination with early Triassic Chaqupu andesite, late Triassicearly Jurassic peraluminous granites and Permian fossils within the metamorphic complex, this finding has led to the conclusion that, prior to Gondwana dispersion in early Mesozoic, the subduction of an ocean plate beneath the northeastern Gondwana margin took place during the PermoTriassic period and that, subsequent outgrowth of NEtrending Gondwana triggered off the final formation of the Lhasa terrain.

Abstract:Located in Tengjiaji of Rongcheng area, Shandong Province, the Macaokuang peridotite lies in the northeastern part of the Sulu ultrahigh pressure metamorphic belt. The protolith of the peridotite is the residual mantle harzburgite, which underwent ultrahigh pressure and then granuliteamphibolite facies metamorphism. Trace and rare earth element abundances of olivine, orthopyroxene and amphibole in the Macaokuang mantle peridotite and the orthopyroxenite veins and amphibolite veins within the peridotite were analyzed, and the result shows that Co and Ni are high and mainly concentrated in olivine, but their contents are low in orthopyroxene and amphibole, suggesting that the bulk rock is enriched in Co and Ni due to the high proportion of olivine in the rock. Although it makes up only 3%~8% of the whole rock, the amphibole controls the contents and distribution patterns of trace and rare earth elements of the bulk rock with the exception of Co and Ni. Orthopyroxene and olivine have much lower trace and rare earth element abundances than amphibole, and the element distribution patterns of orthopyroxene and olivine are quite similar to the pattern of amphibole. Amphibole in orthopyroxenite veins and amphibolite veins is more enriched in trace and rare earth elements than that in peridotite. Geochemistry of the elements shows that peridotite must have experienced repeated metasomatic actions of at least such components as Co and Nirich fluids, LREE, Ba, Sr, Tarich and Th, Uextremely low silicate fluids and carbonic fluids. Fluid metasomatism occurred after UHP metamorphism at a shallow mantle depth. Olivine, orthopyroxene and amphibole in the peridotite together with the intruded veins are characterized by normal mantle oxygen isotopic ratios and show equilibrium each other. Meanwhile, the oxygen fugacity of the peridotite is +1.0~+2.0, falling in the normal continental mantle range, implying that the rock has not experienced metasomatic action of crustal fluids. 

Abstract:The Songshugou ultramafic pluton north of the Shangdan fault is the largest ultramafic body in the East Qinling Orogen and assumes the emplacement contract with the Qinling complex. The pluton is composed mainly of finegrained as well as medium and coarsegrained dunite and plagioclasepyroxene peridotite. Debates exist concerning whether ultramafic rocks and adjacent mafic rocks were formed in the same tectonic cycle and whether they experienced a common metamorphismdeformation event or not. This paper presents new data on the inclusions and trace element concentrations of zircons from garnet amphibolites that occur in a metamorphic contact zone. Studies indicate that the ultramafic intrusion and adjacent amphibolites experienced different tectonic events, and the ultramafic pluton was emplaced in amphibolites formed before. Geochemical data suggest that amphibolites have characteristics of MORB and IAT and likely belong to the Qinling Group.

Abstract:Based on a systematic petrographic and geochemical study and a zircon UPb SHRIMP age analysis, the authors revealed that the age of orehosting volcanics (XC011 rhyolitic tuff) is 180.4±3.5 Ma. This age suggests that the volcanic suite was formed in Early Jurassic instead of formerly widelyaccepted Late Cretaceous. The age of peripheral monzonitic granite (XTM041) is 46.6±0.6 Ma, implying that this granite suite was formed in the oreforming stage of Eocene. According to these data, the authors tend to believe that the Xiongcun superlarge deposit belongs probably to the altered cataclastite type CuAu deposit, and is very similar to Jiaodong “Jiaojiastyle” gold deposits.

Abstract:Siliceous rocks are widely distributed in FengxianTaibai basin and composed mainly of siliceous ankeriteankeritic siliceous rockssiliceous rocks, characterized by stable and long extension and a close relationship with regional mineralization. Therefore, the survey and study of the genesis of these siliceous rocks help conduct regional prospecting. Based on field observation, microscopic examination, LRM and electron microprobe analysis, the author investigated geochemical characteristics of siliceous rocks in such aspects as major elements, trace elements and rare earth elements. It is shown that concentrations of Fe and Mn in siliceous rocks are high whereas concentrations of K, Na and Ti are low in these rocks. The Fe2O3/FeO ratios are lower than 1, suggesting that they were formed in a relatively reduction condition. The Fe, Ti, Mn and Al concentrations also imply that the depositional environment of siliceous rocks belongs to a continental margin. Pb, Zn and Cu in siliceous rocks are obviously concentrated. The ∑REE values are low (12.10×10-6～40.46×10-6) and the differentiation between LREE and HREE is evident (2.34～8.68). The chondritenormalized REE patterns of siliceous rocks are inclined to the right, and Ce and Eu assume intermediately negativepositive anomalies. The variation of Ce anomalies from siliceous rocks to siliceous ankerite also indicates that the depositional environment changed from reduction to oxidation.

Abstract:The Kalamaili ophiolite belt controlled by regional deepfracture zone consists of ultramafic rock bodies，mafic dikes and volcanics. The ultramafic rocks are composed of mantle harzburgites with dunite pods and chromitite ores and characterized by low SiO2， high MgO， LREEenriched Vshaped and LREEslightly enriched patterns. They represent a typical mantle section of the suprasubduction zone (SSZ) setting. The lowTi basalts and their crystallized accumulative dikes comprising gabbro and gabbrodiorite display a lowTi affinity of the island arc tholeiite (IAT) ophiolitic series from the SSZ setting， having， as most distinctive chemical features， low Al2O3， TiO2，K2O+Na2O and K2O<50)， low MgO (1.84%～2.81%， 2.60% on average)， enrichment of incompatible elements and high abundance of REE with LREEenriched REE patterns. They probably are remnants of ocean island，representing the ocean hotspot at the early development stage of the ocean， and might have constituted the hotspot that resulted in the initial extension environment in this region. It can be concluded that the Kalamaili ophiolite belt represents the Devonian oceanic lithosphere relics of the ocean basin that separated the KazkhstanJunggar united continental block from Siberian plate, suggesting that the ocean basin experienced the process from the early intraocean hotspot to the late intraocean plate subduction.

Abstract:The Qilian fold belt is one of the major orogenic belts in China. Traditionally, it is divided into north Qilian fold belt, central Qilian uplift, south Qilian fold belt and Lajishan area. The study area is located at 150 km northeast of Lanzhou City, and its major part belongs to the Maxianshan Group and the adjacent Sinian and Ordovician strata(including Siergou, Tiechenggou, Tianzhusanxia Forest Park, Naxingou and Gangkouzibei).According to the mineral assemblages, microtectonics and mineral chemistry， the PreSinian metamorphic rocks, i.e., the Maxianshan Group, have experienced a complex history of three stages of metamorphism. StageⅠ(amphibolite facies) is the peak metamorphism, whose mineral assemblage is biotite+ calcium amphibole, with the conditions being 618℃ and 0.65 GPa. Stage Ⅱis epidote amphibolite facies with the mineral assemblage epidote+ albite+ calcium amphibole. Stage Ⅲ is greenschist facies with the mineral assemblage actinolite± corundophilite+ calcite. The compositions of calcium amphiboles are homogeneous. The core and rim temperatures of garnets are 418℃ and 545℃, respectively. The Sinian metamorphic rocks are greenschist facies with the mineral assemblage chlorite+ albite+ hematite+ calcite+ quartz. The Ordovician metamorphic rocks are marbles, which contain apatite layers and phlogopite.40Ar-39Ar dating of hornblende and biotite separated from amphibolite and granite yields plateau ages of 340±0.5Ma and 323.4±0.65Ma, respectively, which may represent the reactive ages of the Maxianshan Group.

Abstract:Diagenesis of Carboniferous clastic rocks controlling pore evolution in Tazhong area of Tarim basin was studied quantitatively through core or thin section observation and analysis of data from scanning electron microscope, vitrinite reflectance and inclusion thermometry. The results show that reservoir space of the objective interval is composed of primary intergranular pores and secondary intergranular pores. Mechanical compaction and cementation damaged pores seriously. Compaction decreased the original porosity by 20.7% and cementation only decreased the original porosity by 7.9%. The original porosity was damaged more seriously by compaction than by cementation. Compaction played an important role in the whole process of pore evolution. Dissolution was the only diagenetic action resulting in the improvement of reservoir space and mainly occurred in early diagenetic stage A, the beginning of early diagenetic stage B, the end of the early diagenetic stage B, and the middle diagenetic stage A. In addition, dissolution increased porosity by 3.2%. The research on reservoir diagenesis and the establishment of the porosity evolution model have revealed the stages of pore evolution, which are of great importance to reservoir study and further exploration.

Abstract:Humus existent in soil and water is often closely associated with clay minerals and forms special complexes. The adsorption of heavy metals on clay mineralhumus complexes is different from that on clay minerals or on humus. The authors investigated the adsorption and competition of Cu2+ and Cd2+ on montmorillonitehumic acid complexes in both the single system (Cu2+ or Cd2+) and the binary system (Cu2+and Cd2+). Experimental results show that, in the single system, the adsorption amounts of Cu2+on the complexes are higher than those of Cd2+ and, in particular, the adsorption amounts of both Cu2+and Cd2+increase linearly with the increasing of their initial concentrations. In the binary system, the adsorption amounts of Cu2+ are consistently a bit higher than those of Cd2+. This indicates that the selectivity of complexes for Cu2+ is better than that for Cd2+. The cation exchange process, which occurs between montmorillonite and Cu2+/Cd2+, may be a predominant mechanism in the process of adsorption. Whether in the single system or in the binary system, Cd2+is liable to replacing Ca2+which has the same electrovalence and a slightly larger radius than Cd2+, whereas Cu2+ is liable to replacing Na+ which has a similar radius and a lower electrovalence than Cu2+. Therefore, the adsorption amounts of Cu2+ on complexes in the binary system are obviously lower than those in the single system， while the adsorption amounts of Cd2+ are almost the same in both systems. These results might provide some clues to the migration and fixation of heavy metal ions in soil and water for further exploration.

Abstract:Highgrade black jadeite is a kind of upscale and fashionable jade material that has become one of the jadeites characterized by fastest growing values in the past 20 years. Based on a comparison of mineralogical and geochemical characteristics between black jadeites (inky black jades）from different producing areas of the world, the authors hold that the black jadeites currently on the market can be mainly classified into jadeite jade, omphacitic jadeite jade and hornblende jade whose main components are jadeite, omphacite and dark green hornblende respectively. They include blackchicken jade, ink jadeite and blackkosmochlor from Myanmar and jade negro and galactic gold from Guatemala, with blackchicken jades similar to those from Myanmar also seen in Japan and Kazakhstan. The research results suggest that the main mineral composition, jade structure and inclusion characteristic combinations of black jadeite jades from different producing areas have their respective typomorphic natures, which can be used as the distinctive characteristics for their sources.