Abstract:The Fogang granitoid complex is the largest Late Mesozoic batholith in Nanling region, and the Wushi diorite-hornblende gabbros are the mostbasic end_member of Fogang calc-alkaline series rocks. Both the Wushi diorite-hornblende gabbros and the surrounding granite-granodiorites belong to high-K calc-alkaline series. Based on a systematic comparison of different Al-in-hornblende geobarometers and hornblende-plagioclase geothermometers, the authors have proposed an improved temperature and pressure grid of Al-Ti in hornblende and applied it to estimating crystallization conditions of Wushi diorite-hornblende gabbros. Hornblendes in Wushi diorite-hornblende gabbros crystallized at 820±20℃ and 70～130 MPa, with a XH2O of 0.7±0.1. The hornblendes in surrounding granodiorites crystallized at 820℃ and 260 MPa.

Abstract:Major and trace elements and Sr-Nd isotope data of adakitic high-K calc-alkaline volcanic rocks in Chibzhang Co area are presented, which yield ages of 35～40 Ma. All of the rocks exhibit characteristics of adakites formed by partial melting of an eclogitic lower crust: SiO2＝58%～69%，high K2O,Al2O3 and Sr contents，low Y, Yb contents and Mg＃ values, strong depletion of Nb and Zr, weak depletion of Ti and P，LREE enrichment with no remarkable Eu negative anomaly，ISr＝0.70723～0.70777 and INd＝0.512320～0.512352. The adakitic geochemical features and crustal anatectic isotopic characteristics suggest a primitive magmatic generation process responsiblefor the partial melting of an eclogitic lower crust of northern Tibetan Plateau. It is also implied that the crust was thickened to over 40 km and an eclogiticlower crust was formed in northern Tibet area during Eocene. The adakitic volcanic rocks of 40 Ma indicate that the continental crust of Qiangtang area in Tibetan Plateau has been thickened to over 40 km，and the plateau probably started its uplifting 40 Ma ago.

Abstract:Based on a study of SHRIMP U-Pb chronology of zircons from diabase dykes in Laiwu area of western Shandong, this paper deals with zircon chronology of mafic dyke swarms. Two types of zircons are distinguished: zircons entrapped from the host rock with the concordia age of 2537±16 Ma, and originaligneous zircons with the concordia ages of 1139±25 Ma and 1157±18 Ma. The data suggest that the mafic dyke swarms in Laiwu area were emplaced during Mesoproterozoic. Few original zircons are developed in mafic dykes, so the origin and age populations of zircons should be analyzed with care. It is not proper to regard the average of most values as the real age of dyke emplacement. The field relationship between overlying strata and dyke swarms and the intersecting relations of the intrusions should be studied in detail.

Abstract:Based on a study of Sidaohe area in UHP metamorphic terrane within the Dabieshan Mountains, it is discovered that there exist three types of rock associations, namely eclogite, gneiss and foliated garnet-bearing granites. Eclogites underwent retrograde metamorphism of different degrees, and amphibolites seem to be retrograded products from eclogites. Gneiss is the country rock of eclogites, and there exist mutational relationships in major element components. Major and trace elements and REE in foliated garnet-bearing granites are characterized by enrichment of SiO-2, K-2O Na-2O, Ga, Y and REE components and depletion of K-2O/Na-2O, Al, Ca, Mg, Ti and P. Combined with Rb-Hf-Ta diagram and isotopic and geochronologic data, it is held that this type of granites belong to post-collisional A-type granites. Based on the above evidence, the authors have reached the conclusions that continental slab underwent UHP metamorphism and produced eclogites during its subduction to the depth of the upper mantle, that extensive decompression retrograde occurred in UHP metamorphic rocks and produced amphibolites when UHP slab migrated to the middle and lower crust, and that the UHP slab, together with gneiss and foliated garnet-bearing granites, further moved from the middle and lower crust to the surface and experienced subsequent metamorphism and deformation.

Abstract:The stability of the magma chamber is controlled by interior factors such as the behavior of activities and the cooling rate of the magma chamber as well as exterior factors like the extrusion and vibration of the rocks around the magma chamber. Under certain conditions, the activities of the rocks around the magma chamber can play a crucial role in the stability of magma chamber, especially in the area with frequent crustal movement. The aim of this study is to simulate the processes of the magma chambers of Laoheishan volcano in Wudalianchi area. On the basis of the heat conduction equation and the coupling of Duffing equations of the magma chamber, it is concluded that whether the Laoheishan magma chamber has been cooled or not is closely related to the heating history of the rocks around the magma chamber, and that the magma has approached complete solidification and some nonlinear processes must have existed in the dynamic system of the magma chamber.

Abstract:Tazhong 45 reservoir, lying in the Middle-Upper Ordovician strata of Tazhong area, is a fluoritized carbonate reservoir. There exist many fluorite veins filled with crude oils in its reservoir bed. The well core and microscope observation indicates that fluorite is formed by replacement of calcite. There are many hydrothermal minerals accompanying fluorite, such as pyrite, quartz and chlorite. Two generations of fluid inclusions are observed in fluorite, namely the primary and the secondary inclusions. Most of the primary fluid inclusions have homogenization temperatures between 260 and 310℃, which represent the temperature of hydrothermal fluid responsible for fluorite precipitation. The secondary fluid inclusions have homogenization temperatures between 100 and 130℃, which represent the hydrocarbon charging temperatures because there are many petroleum inclusions among the secondary inclusions. Characteristics of the mineral assemblage and primary homogenization temperatures indicate that the precipitation of fluorite is related to hydrothermal activities in Tazhong area. Theoretically, the volume will be reduced by 33.5% after the replacement of calcite by fluorite, which is likely to raise the reservoir quality to a great extent. There are also numerous intergranular pores filled with hydrocarbons in fluorite. Therefore, the hydrothermal activities and the precipitation of fluorite in Tazhong area greatly improvethe reservoir property and make the Tazhong 45 reservoir more suitable for hydrocarbon accumulation.

Abstract:The electric conductivity of pyrophyllite was measured by means of Sarltron-1260 frequency and phase impedance spectroscopic analyzer under the condition of 1.0, 2.0 GPa and 873～1223 K and on the basis of microcosmic mechanism analysis. The experimental results indicate that (1) the electric conductivity of the sample depends on frequency, (2) the relationship between electric conductivity and temperature is in linear accord with the Arrenhius equation,and (3) the dehydration temperature of pyrophyllite is 1074 K and 1101 K at1.0 GPa and 2.0 GPa, respectively. A conclusion different from previous conclusions has been drawn, which holds that an inflexion appears after dehydration.

Abstract:More than one hundred K feldspars were collected from gold-bearing Vein Ⅰ(K feldspar-quartz vein) and Vein Ⅱ (quartz vein) as well as various other rock types in the Wulashan gold deposit, China. Chemical compositionsof K feldspars were analyzed using electron microprobe analysis (EMPA). The powder X-ray diffraction (XRD) patterns of K feldspars were collected using Cu Kα source. Au contents of the corresponding ore samples were analyzed by fire assay. Q- and R-mode cluster analysis and Spearman rank correlation analysis of the experimental data were performed. The results indicate that K feldspars from gold-bearing veins, magmatic hydrothermal veins and altered wall rocks are intermediate to maximum microclines characterized by higher content of K2O, lower contents of Na2O, CaO and BaO, and relatively small variations in chemical compositions. K feldspars from other rock types are likely sanidine, orthoclase or microclines that show greater variations in chemical compositions and are characterized by lower content of K2O but higher contents of Na2O, CaO and BaO. K feldspars from auriferous samples are much richer in K2O, indicating that gold mineralization might have been related to potassic hydrothermal fluids and intense K feldspar metasomatism. There exist two gold mineralization stages in the Wulashan deposit. K feldspars from the major K feldspar_quartz veins are characterizedby higher K2O and higher formation temperatures of 307～379℃ with an averageof 353℃. K feldspars from the quartz veins of the second stage are characterized by lower K2O and lower formation temperatures of 260～318℃ with an averageof 281℃. These results indicate that the mineralization fluids were associatedwith magmatic hydrothermal events and evolved toward lower temperatures and lower content of K2O, but the hydrothermal fluids of higher K2O and the temperatures of 260～380℃ may favor gold mineralization.

Abstract:Based on such analytical methods as EMPA, XRD and IR, the authors extensively studied a new Cr-bearing edenite variety. The results show that the empirical formula of Cr-bearing edenite is (Na0.50 Ca0.17 K0.06) 0.73 Ca2.00 (Mg3.92 ⅥAl0.79 Cr3+0.06Ti0.04Fe2+0.01Co0.01) 4.83 (Si6.54ⅣAl1.46) 8.00O22(OH)2 according to revised IMA98 amphibole nomenclature, with the deal expression being NaCa2(Mg4Al)Si7AlO22(OH)2. Its unit-cell parameters are a=9.8437（19）A，b=17.9474（37）A,c=5.2796（15)A，β=105.222（17）, V=904.404A3 and Z=2.It has been discovered in its structure that Ca is at the A site, Mg is displaced by Cr and Si by Al. All this indicates that the studied mineral is a new chromic-calcic amphibole related closely to a Si-poor and Ca- and Cr-rich genetic environment. The name given to Cr-bearing edenite is based on the chemical composition and the special color caused by chromium.

Abstract:Surface acid-base properties of kaolinite were investigated by potentiometric surface titration. On the basis of the multi-sites model (assuming the presence of (Al-2OH)()(), (AlOH)()() and (SiOH)()()), relative parameters of proton adsorption/desorption were calculated according to the experimental data which had been corrected in consideration of the kaolinite dissolution. The reactions at every site were also discussed. The influence of various ionic strengths and kaolinite dissolution on the results of potentiometric surface titration was studied. The point-of-zero-net-proton charge of kaolinite (pH-(PZNPC),5.2) differed from the point of zero charge. Below pH 5.2, the positive charge at the kaolinite surface was mainly attributed to the formation of silica rich/aluminum deficient precursor complex and proton adsorption at aluminum sites, whereas above pH 5.2, the negative charge at the kaolinite surface was contributed chiefly by deprotonation of Si and Al sites.