辽宁五龙金矿石英的标型特征及其与金矿化的关系

石英是辽宁五龙金矿含金石英脉矿体中最重要的脉石矿物,而且也是主要的载金矿物。石英的分布及世代、形态、物理性质和成分特征反映了金矿床形成的地质环境,不同特征的石英含金性也不相同,其中第二世代的灰色石英含金量高。石英与金矿化关系密切,是重要的找矿标型矿物。     

黑龙江省平顶山金矿石英的成因矿物学与找矿信息研究

所研究的石英有四个成矿阶段,第一、四成矿阶段石英不含金;第二、三成矿阶段石英含金。细粒、灰白—黄白色石英为重要的宏观找矿标志。SiO_2含量低,Al_2O_3、Na_2O、K_2O含量高,Cu、Pb、Zn、As含量高的石英可作为含金石英的成分标志。双峰和多峰的石英热发光曲线是含金石英的物性标志。     

Dauphiné twinning and texture memory in polycrystalline quartz

Mechanical twinning in polycrystalline quartz was investigated in situ with time-of-flight neutron diffraction and a strain diffractometer. Dauphiné twinning is highly temperature sensitive. It initiates at a macroscopic differential stress of 50–100 MPa and, at 500°C, saturates at 400 MPa. From normalized diffraction intensities the patterns of preferred orientation (or texture) can be inferred. They indicate a partial reversal of twinning during unloading. The remaining twins impose residual stresses corresponding to elastic strains of 300–400 microstrain. Progressive twinning on loading and reversal during unloading, as well as the temperature dependence, can be reproduced with finite element model simulations.     

Pb Isotope Compositions of Shibaqinghao Gold Deposit in Central Inner Mongolia, China

1ＧｅｏｌｏｇｉｃＳｅｔｔｉｎｇＳｈｉｂａｑｉｎｇｈａｏｇｏｌｄｄｅｐｏｓｉｔｉｓｓｉｔｕａｔｅｄｉｎｔｈｅｗｅｓｔｅｒｎｐａｒｔｏｆｔｈｅｎｏｒｔｈｅｒｎｍａｒｇｉｎｏｆｔｈｅＮｏｒｔｈＣｈｉｎａＣｒａｔｏｎ .ＩｔｉｓｃｏｎｔｒｏｌｌｅｄｂｙａｎＥ -ＷｔｒｅｎｄｉｎｇｔｅｃｔｏｎｉｃｚｏｎｅｔｈａｔｉｓｌｏｃａｔｅｄｉｎｔｈｅｍｉｄｄｌｅｕｎｉｔｏｆＤｏｎｇｗｕｆｅｎｚｉＧｒｏｕｐ ,ｗｈｉｃｈｃｏｎｓｉｓｔｓｏｆａｓｅｑｕｅｎｃｅｏｆｇｒｅｅｎｓｃｈｉｓｔ -ｆａｃｉｅｓｍｅｔａｍｏｒ ｐｈｉｃｒ…     

宽甸石柱子-东北沟铜(金、钼)矿床石英热发光研究

石柱子－东北沟铜（金、钼）矿床、矿化点，产于石柱子花岗闪长岩体中。对其大面积取样，并测试了２４７个石英热发光样品，发现其含矿石英热发光曲线主要为单峰型，温度一般为２６０℃±２０℃之间的中温区。这两个特征可作为该地区成矿石英热发光的主要特征。另外还对东北沟铜（金、钼）矿床ＤＺＫ５钻孔样品进行了连续测试，认为矿体深部仍有潜力，不至于马上尖灭。     

The fractal shape of sutured quartz grain boundaries: application as a geothermometer

Along grain boundaries of quartz from metamorphic and igneous rocks complex interfingering (sutures) may occur. Under the light microscope the lengths of the sutures range from approximately 10–1000 m. The sutured grain boundaries are statistically self-similar over one to two orders of magnitude. They represent fractals. Their mathematical counterpart are Koch curves which are developed after two to four iterations. The fractal (Hausdorff-Besicovitch) dimensions D of sutured quartz grain boundaries from different grades of metamorphism are between ca. 1.05 and 1.30. The D-value decreases with increasing temperature during formation of the sutures. On a statistical basis, D can be used as a measure of this temperature and, therefore, as a deformation-related thermometer.     

牟乳石英脉型金矿成矿构造地球化学实验研究

牟乳金矿带位于华北克拉通东缘的胶北花岗岩－绿岩地体东部活化区。区内元古宙荆山群绿岩建造是金的矿源层。北北东向断裂为主要控矿控矿构造。金矿床主要为含金硫化物石英脉型。金的成矿作用与一定的构造－热－动力事件相联系。根据成矿特征和物理化学条件,作者进行了成矿构造地球化学实验。实验表明：分散在黄铁矿中的Ａｕ等成矿元素在高温高压（剪）应力作用下,产生迁移。金的迁移可以固态纳米金形式及在化学迁移作用下进行。在     

南黄海4个沉积岩芯的热释光测年及地层划分

本文利用热释光技术对南黄海4个柱状岩芯样品进行测年,结果与其他方法所获年代相符甚好;并综合岩性、古地磁和~(14)C等资料对该海区第四纪地层进行划分。对此,初步确定其全新世地层厚度变化于十几厘米至几米之间。     

Retrograde evolution of quartz segregations from the Dos Picos shear zone in the Nevado-Filabride Complex (Betic chains,Spain). Evidence from fluid inclusions and quartz c-axis fabrics

Synkinematic quartz veins are ubiquitous in the shear zone separating the Veleta unit from the Calar Alto unit in the internal part of the Betic Cordilleras. They have been studied with respect to quartz c-axis fabrics, microstructures and fluid inclusions. Veins were probably generated during syn-metamorphic stacking of the units at P = 500 – 600 MPa and T = 400 – 500°C. Quartz displays two groups of microstructures in the shear zone: (1) older coarse-grained mosaics (CGM) resulting from exaggerated grain growth; and (2) younger fine-grained mosaics (FGM) developed at the expense of the former. The fine-grained mosaics show polygonal granoblastic and elongate mosaic microstructures in general, with ribbon microstructures often found near the boundary of the units. Fluids contained in secondary inclusions vary from high salinity brines to different types of CO₂—brine mixtures and low density CO₂ fluids. Differences in composition and P-T trapping conditions are indicated for the different types of inclusions. Some fluid inclusions are older than the FGM, whereas others are younger, thus constraining the P- T conditions at which the two microstructural events took place. Fluid inclusion evidence suggests conditions of P_fluid > 170 MPa and T 370–430°C for the CGM and P_fluid 20–80 MPa and T > 340°C for the FGM.The quartz c-axis fabrics dealt with here correspond to the second recrystallization event, as little evidence of older fabrics is preserved in the shear zone. C-axis patterns vary across the shear zone from slightly asymmetrical type I crossed girdles in the hanging wall and footwall to more asymmetrical crossed girdles at the boundary of the units. This indicates a correlative increase in the magnitude of the heterogeneous shear strain in the same direction. Most of the deformation is concentrated at the top of the Veleta unit. The sense of movement is top to the west, in agreement with other kinematic markers.The quartz c-axis fabrics resulted from dynamic recrystallization during simple shear. The retrograde P-T path inferred from fluid inclusion analysis, along with other geological and geochronological evidence, indicates that this deformation is coeval with a reduction in the crustal overburden.Geochronological and stratigraphic data show that the proposed Dos Picos extensional detachment, separating the Calar Alto and Veleta units, took place during the early Miocene, synchronous with the intense thinning of the Nevado-Filábride Complex and of the whole continental crust underlying the Alborán Basin.     

Millennial timescale resolution of rhyolite magma recharge at Tarawera volcano: insights from quartz chemistry and melt inclusions

Most rhyolite eruption episodes of Tarawera volcano have emitted several physiochemically distinct magma batches (∼1–10 km³). These episodes were separated on a millennial timescale. The magma batches were relatively homogeneous in temperature and composition at pumice scale (>4 cm), but experienced isolated crystallisation histories. At the sub-cm scale, matrix glasses have trace element compositions (Sr, Ba, Rb) that vary by factors up to 2.5, indicating incomplete mixing of separate melts. Some quartz-hosted melt inclusions are depleted in compatible trace elements (Sr, Ti, Ba) compared to enclosing matrix glasses. This could reflect re-melting of felsic crystals deeper in the crystal pile. Individual quartz crystals display a variety of cathodoluminescence brightness and Ti zoning patterns including rapid changes in melt chemistry and/or temperature (∼50–100°C), and point to multi-cycle crystallisation histories. The Tarawera magma system consisted of a crystal-rich mass containing waxing and waning melt pockets that were periodically recharged by silicic melts driven by basaltic intrusion. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.