Genesis of the Gold Deposit in the Indus-Yarlung Tsangpo Suture Zone, Southern Tibet: Evidence from Geological and Geochemical Data

The Nianzha gold deposit,located in the central section of the Indus-Yarlung Tsangpo suture(IYS) zone in southern Tibet,is a large gold deposit(Au reserves of 25 tons with average grade of 3.08 g/t) controlled by a E-W striking fault that developed during the main stage of Indo-Asian collision(~65-41 Ma).The main orebody is 1760 m long and 5.15 m thick,and occurs in a fracture zone bordered by Cretaceous diorite in the hanging wall to the north and the Renbu tectonic melange in the footwall to the south.High-grade mineralization occurs in a fracture zone between diorite and ultramafic rock in the Renbu tectonic melange.The wall-rock alteration is characterized by silicification in the fracture zone,serpentinization and the formation of talc and magnesite in the ultramafic unit,and chloritization and the formation of epidote and calcite in diorite.Quartz veins associated with Au mineralization can be divided into three stages.Fluid inclusion data indicate that the deposit formed from H_2O-NaCl-organic gas fluids that homogenize at temperatures of 203℃-347℃ and have salinities of 0.35wt%-17.17wt%NaCl equivalent.The quartz veins yield δ~(18)O_(fluid) values of 0.15‰-10.45‰,low δD_(V-SMOW)values(-173‰ to-96‰),and the δ~(13)C values of-17.6‰ to-4.7‰,indicating the ore-forming fluids were a mix of metamorphic and sedimentary orogenic fluids with the addition of some meteoric and mantle-derived fluids.The pyrite within the diorite has δ~(34)S_(V-CDT) values of-2.9‰-1.9‰(average-1.1‰),~(206)Pb/~(204)Pb values of 18.47-18.64,~(207)Pb/~(204)Pb values of 15.64-15.74,and ~(208)Pb/~(204)Pb values of 38.71-39.27,all of which are indicative of the derivation of S and other ore-forming elements from deep in the mantle.The presence of the Nianzha,Bangbu,and Mayum gold deposits within the IYS zone indicates that this area is highly prospective for large orogenic gold deposits.We identified three types of mineralization within the IYS,namely Bangbu-type accretionary,Mayum-type microcontinent,and Nianzha-type ophiolite-associated orogenic Au deposits.The three types formed at different depths in an accretionary orogenic tectonic setting.The Bangbu type was formed at the deepest level and the Nianzha type at the shallowest.     

2000国家大地坐标系转换常见问题分析

在现有成果向2000国家大地坐标系转换工作中,各省市都做了很多理论研究和实际转换工作。本文阐述了现有成果向2000国家大地坐标系转换的方法,对不同数据、不同方法转换过程中常见的问题进行汇总、整理,并分析问题产生的原因及对成果的影响,为今后现有成果向2000国家大地坐标系转换工作提供参考和建议,以确保成果转换的质量。     

天津市GPS连续站数据的处理与分析

简要介绍了天津市12个GPS连续运行站的建设状况和在各领域中的应用,通过最新的精密处理策略对一年多的数据进行计算,得到精确的ITRF坐标时间序列,并分析了ITRF框架下天津市地面水平和垂直坐标变化规律,为GPS技术的进一步运用打下基础。     

光合细菌在海湾扇贝人工育苗中应用的研究

光合细菌是一类组份较全且营养价值较高的细菌。在缺氧弱光条件下，具有处理低分子有机物、净化水质等显著功效。本研究利用了光合细菌所具有的独特生理功能和生态习性，在海湾扇贝人工升温育苗过程中，以单胞藻为基础饵料适当添加光合细菌，增强了海湾扇贝整体营养水平和改善了育苗水体生态环境条件，促进了亲贝性腺发育，提高了幼虫生长率。亲贝性腺指数平均日增长达２％以上，幼虫日平均增长１３．８５μｍ，同时，光合细菌可降低     

南极格罗夫山陨石岩石学特征Ⅱ:平衡型普通球粒陨石

我国第16次南极科考队回收的28块陨石中,除1块火星陨石、1块HED陨石和6块非平衡L3型陨石外,其余20块为平衡型普通球粒陨石。根据橄榄石的平均Fa值、低Ca辉石的平均Fs值和Fe-Ni金属含量将这20块陨石分别划分为H、L和LL等化学群;根据球粒结构、基质重结晶程度和矿物成分对这些陨石进行岩石类型的划分。由于平衡型普通球粒陨石已达热力学平衡,橄榄石和低Ca辉石的成分相当均一,并且平均Fa和Fs值均与陨石的含Fe总量呈很好的反比关系,因此橄榄石平均Fa值和低钙辉石平均Fs值是平衡型陨石重要的化学群分类标准。20块平衡型普通球粒陨石的化学-岩石类型为:6个H群(3个H4、1个H5和2个H6)、9个L群(3个L4、1个L5和5个L6)和5个LL群(2个LL4、3个LL5)。     

内蒙古蓬勃山地区土壤地球化学特征及找矿方向

蓬勃山地区位于天山—阴山构造带东段,隶属于甜水井—乌珠尔嘎顺—雅干成矿带。研究区矿化主要表现为金矿化,矿化类型较为单一。通过对研究区的土壤地球化学测量,共圈出单元素异常66处。根据各元素聚类分析结果,并结合元素异常的套合情况,进一步圈定了4处组合异常。综合考虑研究区土壤地球化学异常特征、土壤地球化学组合异常所在位置及异常与地质体、矿脉的关系,在研究区内圈定了三个找矿靶区并进行了工程验证,取得了良好的找矿效果。     

Zircon Senstive High Resolution Ion Microprobe (SHRIMP) study of granitoid intrusions in Zhaoye Gold Belt of Shandong Province and its implication

The zircon Sensitive High Resolution Ion Microprobe (SHRIMP) results show that granitoid intrusions in Zhaoye Gold Belt were emplaced at two periods of Mesozoic: Linglong and Luanjiahe types of granitic intrusions were emplaced between 160 Ma and 150 Ma (late Jurassic); Guojialing type of granodioritic intrusions, 130 Ma and 126 Ma (early Cretaceous). All the three types contain at least two major generations of inherited zircons with Precambrian (>650 Ma) and early Mesozoic ages (200–250 Ma), respectively. The former suggests that these plutonic rocks are of crustal origin and that Precambrian basement with component of sialic crust up to 3.4 Ga old (Middle Archean) exists in the region. The presence of abundant inherited zircons with early Mesozoic age indicates that the Precambrian basement was affected by a major tectono-thermal event, that is the collision of the North and South China blocks, at 250 Ma to 200 Ma. SHRIMP results also indicate that the gold mineralization in the region took place between 126 Ma and 120 Ma. Project supported by the Sino-Australian Economic and Technical Fund.     

江苏省粮食单产空间差异的因素分解

区分粮食单产空间差异的来源,是粮食单产空间特征和成因机制研究的一个基础问题,可以为粮食促产政策的制定提供较为可靠的依据。基于粮食作物配置的视角,以江苏省为例,运用因素分解法,探讨粮食单产空间结构及单产变化空间差异的贡献因素。结果表明:1)当前江苏省粮食作物配置结构的空间差异可以说明近80%的粮食单产的空间差异,而江苏省粮食生产力的空间分布与粮食单产空间差异仅低度相关。2)1990s中期以来,江苏省粮食单产增幅有南弱北强的倾向,主要来源是生产力效应,结构效应对这种空间分化起到强化作用。因此,相对于笼统的粮食单产指标,排除结构因素的粮食生产力因素能更为准确地体现粮食现实生产力的变化。     

FY-3D MERSI-II云顶产品算法及精度检验

云顶温度和云顶高度作为基本的云参数,在云的热辐射强迫估计,航空气象保障,数值天气预报,天气气候研究等方面具有十分重要的意义。FY-3D/MERSI-II云顶温度产品基于云在红外波段的发射率假设,利用两个红外分裂窗通道(11.0 μm、12.0 μm)结合一维变分方法寻找最优云顶温度层,再利用数值天气预报廓线产品插值反演对应的云顶高度和压强。利用AQUA/MODIS所提供的云产品数据对FY-3D/MERSI-II云顶温度、云顶高度、云顶压强产品进行精度检验,结果表明:FY-3D/MERSI-II水云云顶温度精度为-1.2±4.6 K,云顶高度精度为1.4±1.8 km,云顶压强精度为-140.9±114.5 hPa;厚冰云云顶温度精度为7.0±6.0 K,云顶高度精度为-1.0±0.9 km,云顶压强精度为37.1±36.0 hPa;混合云云顶温度精度为1.5±8.5 K,云顶高度精度为0.8±2.2 km,云顶压强精度为-87.4±157.8 hPa,单层卷云和多层云的反演偏差较大。辐射传输模式在云顶性质反演中有十分关键的作用,但目前对冰云特别是卷云的性质认识不足,因此如何精确描述冰晶辐射特性,提高冰云特别是卷云辐射传输的模拟精度将是下一步的工作重点。