Zircon LA-ICP-MS U-Pb dating and Sr-Nd isotope study of the Guposhan granite complex, Guangxi, China

Zircon U-Pb dating by the LA-ICP-MS method was applied to determining the ages of different units of the Guposhan granite complex, among which the East Guposhan unit is 160.8±1.6 Ma, the West Guposhan unit is 165.0±1.9 Ma, and the Lisong unit is 163.0±1.3 Ma in age. Much similarity in ages of the three units has thus proved that the whole Guposhan granite complex was formed in the same period of time. They were the products of large-scale granitic magmatism through crust-remelting in the first stage of the Middle Yanshanian in South China. However, the three units have differences both in petrology and in geochemistry. Besides the differences in major, trace and rare-earth elements, they are distinct in their Rb-Sr and Sm-Nd isotopic compositions. The East Guposhan unit and Lisong unit and its enclaves have a similar (87Sr/86Sr)i value of 0.7064 with an average of εNd(t)=-3.03, indicating that more mantle material was evolved in the magma derivation; whereas the West Guposhan unit has a higher (87Sr/86Sr)i value of 0.7173 but a lower εNd(t) value of -5.00, and is characterized by strong negative Eu anomalies and higher Rb/Sr ratios, suggesting that its source materials were composed of relatively old crust components and new mantle-derived components. In addition, an inherited zircon grain in the East Guposhan unit (GP-1) yielded a 206Pb/238U age of 806.4 Ma, which is similar to the ages of the Jiulin cordierite granite in northern Jiangxi and of the Yinqiao migmatic granite in Guangxi in the HZH granite zone. All this may provide new evidence for Late Proterozoic magmatism in the HZH granite zone.     

论兰坪金顶超大型铅锌矿容矿角砾岩的成因

兰坪金顶超大型铅锌矿容矿角砾岩分为两类：一是构造-膏溶角砾岩,不含矿,胶结物孢粉组合显示晚三叠世特征;二是底辟-侵位角砾岩,含铅锌、黄铁矿、天青石和硬石膏矿化,是重要的矿石类型之一,呈脉状产出,系构造-膏溶角砾岩底辟-侵位的产物。它们并非是古新世滑塌堆积成因的角砾岩,不应划归于老第三系云龙组。流行的金顶超大型铅锌矿成矿模式需要重新审定。     

大井锡多金属矿床深部闪长岩体的发现及找矿意义

根据大井西部矿区ZK-29-3、ZK-49-2钻孔中发现的闪长岩体及其岩石学特征,以及对钻孔岩石地球化学特征的分析,论述大井锡多金属矿床深部发现闪长岩体的找矿意义。初步认为,矿区深部存在第二矿化空间和新的矿化类型,具有斑岩系列钼（金）多金属矿的找矿潜力。     

内蒙古查干诺尔铜矿区矿石特征及成因探讨

查干诺尔铜矿床产在西伯利亚板块和华北板块汇聚带附近,华力西晚期构造岩浆带内。成矿与早二叠世洋盆闭合,后碰撞高钾钙碱性花岗岩类岩浆演化晚期的钾质花岗岩有关。铜矿(化)体呈细脉浸染状产在钾质花岗岩的内外接触带内。铜矿石的主要金属矿物为黄铜矿、黄铁矿、闪锌矿、方铅矿等;化学组分以铜、钼、金、银、铅、锌为主。主要的矿化发生在热液期,围岩蚀变明显,有钾长石化、绢英岩化、高岭土化、青盘岩化等。铜矿形成在华力西晚期,属斑岩型铜矿床。     

ArcGIS空间分析技术在地下水评价中的应用

ArcGIS是目前世界具有代表性的地理信息系统，其强大的空间分析技术，在各行业中得到广泛应用。本文就空间分析技术在地下水评价中的应用进行了探讨，并在实际工作中成功地进行了研究区域的地下水评价，其高效特点使工作强度大大减小，是值得进一步推广的地下水评价方法。     

Flat rare earth element patterns as an indicator of cumulate processes in the Lesser Qinling carbonatites, China

The Lesser Qinling carbonatite dykes are mainly composed of calcites. They are characterized by unusually high heavy rare earth element concentrations (HREE; e.g. Yb > 30 ppm) and flat to weakly light rare earth element (LREE) enriched chondrite-normalized patterns (La/Yb_n = 1.0–5.5), which is in marked contrast with all other published carbonatite data. The trace element contents of calcite crystals were measured in situ by laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS). Some crystals show reduced LREE from core to rim, whereas their HREE compositions are relatively constant. The total REE contents and chondrite-normalized REE patterns from the cores of carbonate crystals are similar to those of the whole rock. The carbon and oxygen isotopic compositions of calcites fall within the range of primary, mantle-derived carbonatites. The initial Sr isotopic compositions (0.70480–0.70557) of calcites are consistent with an EM1 source or mixing between HIMU and EM1 mantle sources. However these sources cannot produce carbonatite parental magmas with a flat or slightly LREE enrichment pattern by low degrees of partial melting. Analyses of carbonates from other carbonatites show that carbonates have nearly flat REE pattern if they crystallize from a LREE enriched carbonatite melt. This implies that when carbonates crystallize from a carbonatite melt the calcite/melt partition coefficients (D) for HREE are much greater than the D for the LREE. The nearly flat REE patterns of the Lesser Qinling carbonatites can be explained if they are carbonate cumulates that contain little trapped carbonatite melt. Strong enrichment of HREE in the carbonatites may require their derivation by small degrees of melting from a garnet-poor source.     

水资源优化配置的研究与展望

目前全国水资源优化配置的研究依然停留在借鉴和摸索阶段,对水资源优化配置的主要任务、遵循的原则、配置方案以及未来的发展方向进行了探讨.     

LBM钻井液在绳索取心钻进中的应用

LBM钻井液是一种低粘度低失水量的高效造浆材料，通过在绳索取心中应用，证明了LBM钻井液具有良好的抑制水敏性地层膨胀与分散的能力．可有效防止粘附卡钻事故及解决钻杆内壁结垢问题．是绳索取心钻进较理想的钻井液材料。     

改善钢筋混凝土短柱抗震性能的研究

简要介绍了改善钢筋混凝土短柱抗震性能的若干措施。为进一步提高短柱的抗震性能，本文提出了内藏“斜向劲性核心束”矩形截面混凝土短柱，并进行了7根短柱的抗震性能试验研究，试验表明，内藏“斜向劲性核心束”矩形截面混凝土短柱比普通矩形截面短柱的抗震性能显著提高。     

Wavefield continuation datuming using a near surface model

When topography and low velocity zone differences vary greatly, conventional vertical static time shifts will cause wavefield distortion and influence wave equation seismic imaging for seismic data acquired on a complex near surface. In this paper, we propose an approach to datum correction that combines a joint tomography inversion with wavefield continuation to solve the static problem for seismic data on rugged acquisition topography. First, the near surface model is obtained by refracted wave tomography inversion. Second, the wavefield of sources and receivers are continued downward and upward to accomplish datum correction starting from a flat surface and locating the datum above topography. Based on the reciprocal theorem, Huygens＇ and Fresnel principles, the location of sources and receivers, and regarding the recorded data on the surface as a secondary emission, the sources and receivers are upward-continued to the datum above topography respectively. Thus, the datum correction using joint tomography inversion and wavefield continuation with the condition of a complex near surface is accomplished.