Recent Progress in the Impact of the Tibetan Plateau on Climate in China

Studies of the impacts of the Tibetan Plateau （TP） on climate in China in the last four years are reviewed. It is reported that temperature and precipitation over the TP have increased during recent decades. From satellite data analysis, it is demonstrated that most of the precipitation over the TP is from deep convection clouds. Moreover, the huge TP mechanical forcing and extraordinary elevated thermal forcing impose remarkable impacts upon local circulation and global climate. In winter and spring, stream flow is deflected by a large obstacle and appears as an asymmetric dipole, making East Asia much colder than mid Asia in winter and forming persistent rainfall in late winter and early spring over South China. In late spring, TP heating contributes to the establishment and intensification of the South Asian high and the abrupt seasonal transition of the surrounding circulations. In summer, TP heating in conjunction with the TP air pump cause the deviating stream field to resemble a cyclonic spiral, converging towards and rising over the TP. Therefore, the prominent Asian monsoon climate over East Asia and the dry climate over mid Asia in summer are forced by both TP local forcing and Eurasian continental forcing.
Due to the longer memory of snow and soil moisture, the TP thermal status both in summer and in late winter and spring can influence the variation of Eastern Asian summer rainfall. A combined index using both snow cover over the TP and the ENSO index in winter shows a better seasonal forecast.
On the other hand, strong sensible heating over the Tibetan Plateau in spring contributes significantly to anchor the earliest Asian monsoon being over the eastern Bay of Bengal （BOB） and the western Indochina peninsula. Qualitative prediction of the BOB monsoon onset was attempted by using the sign of meridional temperature gradient in March in the upper troposphere, or at 400 hPa over the TP. It is also demonstrated by a numerical experiment and theoretical study that the heating over the TP lea     

陕西凤县八方山-二里河（铜）铅锌矿床地质特征及成矿模式

在综合分析凤-太矿集区成矿构造特征的基础上，依据以往总结的凤．太矿田铅锌、金矿聚矿构造模式，通过对八方山-二里河铅锌矿床地质特征的分析，总结了找矿标志，初步认为八方山-二里河（铜）铅锌矿床的成矿模式为：“前泥盆纪海底热水喷流沉积一印支-燕山期构造改造型”铅锌矿床。认为成矿物质来源于基底，后期的构造-岩浆改造使基底成矿元素活化，沿同生断裂迁移、改造，最后在泥盆系中形成的扩容性构造部位富集成矿。提出了下一步扩大找矿的方向和建议。     

预测矿井涌水量的计算级别与精度评述

根据水利部2005年发布的《建设项目水资源论证导则（试行）》技术文件中的有关规定与要求,参照《供水水文地质勘察规范》以及《固体矿产资源/储量分类,》认为地下水可开采量与预测矿井涌水量的计算可按勘查研究程度,将其可分为A、B、C、D、E等5个精度等级。参照各级别的允许误差,论证了目前矿井涌水量预测计算公式及方法的可靠程度。     

SHRIMP U-Pb zircon age,geochemistry and Nd-Hf isotope of Neoproterozoic mafic dyke swarms in western Sichuan:Petrogenesis and tectonic significance

Neoproterozoic magmatic rocks are widespread in the western margin of the Yangtze block, and their origin and genesis have significant implications for understanding the evolution of the Rodinia super- continent. However, there are currently two opposing interpretations for their petrogenesis and tectonic setting: mantle plume-related and island arc origin. To further verify these two competing models, SHRIMP U-Pb zircon age determinations and geochemical and Nd-Hf isotopic analyses are conducted on the mafic dykes in the Kangdian Rift, western Sichuan. U-Pb dating suggests that these mafic dykes were emplaced at 780―760 Ma, spatially and temporally coeval with the Kangding granitoid complex. The parental magmas of these dykes were derived from a depleted asthenosphere mantle source likely triggered by an anomalously-hot mantle plume. Despite some arc-geochemical features caused by variable degrees of contamination of young island arc crust during magma ascending and emplace- ment, they show general geochemical and Nd-Hf isotopic features similar to those of the intraplate basalts. Our results support the reconstruction model of Rodinia in which the South China block was located between Australia and Laurentia.     

达县—宣汉地区长兴组礁滩白云岩成岩过程中的孔隙演化

川东北达县—宣汉长兴组礁滩白云岩具有良好的油气储集潜力。作者通过大量岩石常规薄片、铸体薄片观察研究,发现该礁滩白云岩储层储集空间主要为次生成因的晶间孔、晶间溶孔、粒间粒内溶孔、生物体腔内溶孔和生物格架间溶孔。这些孔隙的形成和演化除了受沉积作用、构造作用和有机质热演化史的影响外,还受成岩作用的控制。首先在海底-暴露-浅埋藏环境下,压实及胶结使原生孔隙基本消失;而准同生混合水白云石化及早期暴露溶蚀作用改变了沉积物内部结构,形成众多微小孔隙的网络及溶孔,为后期形成大量孔隙创造了条件。其次在中—深埋藏环境下,强烈的重结晶作用和溶蚀作用使得岩石形成大量的次生孔隙,大大提高了礁滩白云岩的储集性能。     

气候波动和土地覆盖变化下的黄河源区水资源预测

以黄河源区为研究对象,以分布式水文模型SWAT为研究工具,建立不同气候波动和土地覆盖变化情景,模拟和预测未来水资源的变化。针对黄河源区特殊的下垫面条件,着重冰雪和冻土的水文过程调试,对模拟结果的评价显示,SWAT模型能够较好地模拟黄河源区的水资源变化。不同情景下演算得出的水资源量数据可信,具有一定的实用意义,随着认识的深入和模型结构以及参数的优化,模型在寒区水资源研究和管理中会发挥更大作用。     

离子色谱法测定水果和蔬菜中硝酸盐

利用DIONEX-2020i离子色谱仪、IonPac AS3分离柱对蔬菜和水果中硝酸盐进行测定。通过．等冀合适的前处理方法，获得纯清溶液。提出只使用分离柱，以提高灵敏度、缩短出峰时间和改善峰形。方法精密度好、检出限低、操作简便快速，用于实际样品的检测，10次测定的相对标准偏差小于2％，加标回收率为97％～98％。     

CCSD HP-UHP变质岩中磷灰石稀土元素(REE)地球化学及其示踪意义

磷灰石是一种能在UHP变质峰期稳定存在并富含稀土元素(REE)的常见副矿物,其REE组成变化可以对变质过程进行地球化学示踪。本文利用激光剥蚀等离子光谱仪(LA-ICP-MS)对中国大陆科学钻探(CCSD)钻井中及其附近出露的不同变质程度的HP-UHP变质岩(榴辉岩、角闪(片)岩和片麻岩)中的磷灰石进行了REE组成原位测定,结果显示不同围岩中磷灰石的REE组成特征及其相关系数变化很大,其球粒陨石标准化配分曲线可以分为3大类:Ⅰ.轻稀土(LREE)富集型,其REE总量(∑REE)很高,可达n×1000×10~(-6);Ⅱ.中稀土(MREE)富集型,其(La/Sm)_N<1,Eu异常变化较大;Ⅲ.重稀土(HREE)富集型,其配分曲线呈明显的左倾形式,∑REE总量很低,仅为9.228×10~(-6),且具明显的Eu负异常。磷灰石颗粒原位分析显示从边部到中心∑LREE有逐渐升高的趋势,表明了在俯冲折返的过程发生过短时增温作用,并极有可能发生过部分熔融。部分熔融过程中磷灰石中的LREE将与其它大离子半径元素一起优先释放。     

起伏地表条件下的声波散射数值模拟的积分方程法

从散射理论的角度来看,起伏地表可以看作是一种特殊的扰动介质,因此应用散射积分方程求解起伏地表条件下的散射场在理论上是可行的。从三维频率域声波方程出发,由格林函数定理,得出起伏地表条件下的散射积分方程。散射积分方程为关于起伏地表的面积分和与速度扰动体有关的体积分之和,同时给出了格林函数在奇异点的积分方法。由于数值离散求解积分方程存在着计算时间太长和存储内存不足的问题,采用电磁散射积分方程的拟解析近似的方法。在假设反射函数为缓变函数的基础上,最终得到其近似表达式,因此散射场的数值求解不必再借助于代数方程组,只要进行数值积分即可。这种方法避开了传统数值计算方法存在的问题,为地震散射波场快速正演模拟打下了基础。理论分析表明,这种方法适用于小扰动的问题。当扰动较大时,拟解析近似会产生较大的误差。     

均匀介质中F-K反偏移法正演模拟

F-K反偏移法正演模拟是在给定地质模型后通过构建人工偏移场,再对人工偏移场进行F-K反偏移来实现。人工偏移场的构建是在地质模型上直接放上经正确拉伸和幅度校正后的地震脉冲子波。F-K反偏移中插值映射采用两点sinc插值,其能避免假同相轴的出现且具有较快的速度。奇异点处理使用泰勒近似展开。最后对凹陷模型进行了F-K反偏移法正演模拟实现,得到了预期的效果。