西藏那曲地区嘎加组闪长玢岩LA-ICP-MS锆石U-Pb年龄与地球化学特征

西藏那曲地区的中—晚三叠世嘎加组中存在一套闪长玢岩,对这套闪长玢岩进行了LA-ICP-MS锆石U-Pb同位素测定,获得的年龄为115.4±0.6Ma,属早白垩世,与区域上多尼组和则弄群时代一致。闪长玢岩Si O2含量均值为57.96%,富集Rb、Th元素,亏损Nb、P、Ti元素,与上地壳具有相似的蛛网图曲线。εHf(t)值在2.0~4.1之间,平均值为3.0,岩浆来自新生地壳。结合地球化学和构造环境综合分析,闪长玢岩可能形成于拉萨地块和羌塘地块碰撞环境,115Ma时研究区洋壳俯冲作用已结束,进入陆—陆碰撞的演化阶段,随着羌塘地块与拉萨地块的碰撞,地壳不断加厚,慢慢聚集在浅部岩浆房中的大量岩浆把已经加厚的地壳不断加热,从而引起上覆地壳的部分熔融。     

Zircon U‐Pb age,Trace Element,and Hf Isotopic Compositions of Nordmarkite in the Lizhuang Rare Earth Element Deposit in the Western Margin of the Yangtze Block

The Mianning–Dechang(MD) rare earth element(REE) belt, located in the northern Kangdian axis(KDA) in the western margin of the Yangtze platform, is one of the most economically significant REE mineral belts in China. REE mineralization is associated with Himalayan carbonatite–alkaline complexes. The Lizhuang nordmarkite occurred in the northern part of the MD REE belt. The majority of zircons from the Lizhuang nordmarkite are characterized by pronounced positive Ce yet slightly negative Eu anomalies and high U/Yb. Moreover, all zircons have stable Hf isotopic compositions with initial ~(176) Hf/(~(177)Hf) ratios ranging from 0.282739 to 0.282808 and an average value of 0.282773. The negative Lu/Hf and positive ε_(Hf)(t) range from-0.98 to-0.94(average value of-0.96) and from-0.56 to 1.89(the majority is positive, with an average of 0.66), respectively. These characteristics indicate that the rock is derived from an enriched mantle and subducted material. LA-ICP-MS analysis of the zircons from the intrusion yields a weighted mean ~(206)Pb/(~(238)U) age of 28.57±0.61 Ma. During this period, the tectonic activity in the KDA is not plate subduction but an intraplate tectonic exhibiting fold–thrust and strike–slip behaviors in the western marginal zone of the Yangtze platform(WMYB). We suggest the possibility of an existing eastward old slab subduction under WMYB combined with a regional tectonic evolution. The Lizhuang nordmarkite may be derived from an enriched mantle beneath the western part of the Yangtze craton, which originated from the remelting of the Tethys subducting slab, because of the Himalayan strike–slip that formed a special type of REE deposit called strike–slip-type REE deposits.     

Metamorphic Rock-hosted Disseminated Gold Deposits—A Case Study of the Xiaotongjiapuzi Gold Deposit of Eastern Liaoning

The Xiaotongjiapuzi gold deposit occurs in a Palaeoproterozoic rift accretionary terrane in eastern Liaoning and is hosted by a carbonate formation of the Dashiqiao Formation, Liaohe Group. The metamorphic grade of the host rock is low amphibolite-high greenschist facies. Gold, which is mainly invisible, is distributed in pyrite and arsenopyrite. The grains of Au-bearing sulphide minerals are fine, ranging from 0.0 n to 1 mm. The wall-rock alterations are characterized by low-temperature silification, hydro-sericitization, sericitization and carbonatization. The homogenization temperatures of the fluid inclusions in quartz closely associated with gold mineralization range from 140 to 240° C. The metallogenic age represented by the Ar-Ar isotopic age of sericite is 167 Ma. Comparisons and studies show that the Xiaotongjiapuzi gold deposit can be classified as the submicron-sized disseminated deposit (analogous to the Carlin-type) hosted in metamorphic rocks.     

越南岸外晚第四纪上升流与东亚夏季风变迁

通过对南海西部越南岸外１７９５４—３柱状样中浮游和底栖有孔虫的定量分析,结合碳酸钙、有机碳和稳定同位素数据,获得南海西部上升流区近２０万年来的古海洋学记录,进而讨论了晚第四纪东亚夏季风的变迁。结果表明,在间冰期,尤其是末次间冰期,越南岸外出现表层海水古温度低、温跃层浅、生产力高,同时底层海水富营养的现象,说明上升流的存在,且该上升流有从氧同位素５期(ＭＩＳ５期)向１期逐渐减弱的趋势。结合南海现代海流及生产力分布的研究,推断该上升流由东亚夏季风驱动,其强弱的变化说明,东亚夏季风在近２０万年来有间冰期增强、冰期减弱,且从ＭＩＳ５期向ＭＩＳ１期递减的特征。     

东方肝胆医院基坑土钉墙支护测试

通过对工程从土钉内力、喷层土压、挡墙的变形及环境影响范围等方面量测,研究复合型土钉墙支护的工作特性,为理论研究及工程设计提供了有益的依据。     

A study of soil water movement combining soil water potential with stable isotopes at two sites of shallow groundwater areas in the North China Plain

In the shallow groundwater areas of the North China Plain (NCP), precipitation infiltration and evapotranspiration in the vertical direction are the main processes of the water cycle, in which the unsaturated zone plays an important role in the transformation process between precipitation and groundwater. In this paper, two typical sites in Cangzhou (CZ) and Hengshui (HS) of Hebei province with shallow water tables were selected to analyse the relationship among precipitation, soil water and groundwater. At each site, precipitation, soil water at depths 10, 20, 30, 50, 70, 100, 150, 200, 300 cm, and groundwater were sampled to analyse the stable isotope compositions of hydrogen and oxygen. The soil water potentials at the corresponding depths were observed. Although the climates at the two sites are similar, there are some differences in the infiltration process, soil water movement and groundwater recharge sources. Evaporation occurred at the upper depths, which led to the decrease of soil potential and the enrichment of heavy isotopes. At the CZ site, precipitation infiltrated with piston mode, and an obvious mixture effect existed during the infiltration process. Preferential flow may exist in the soil above 100 cm depth. However, at the HS site soil water moved in piston mode, and groundwater was mainly recharged by precipitation. When precipitation recharged the groundwater it experienced a strong evaporation effect. The results of the soil water movement mechanism provides the transformation relationship among precipitation, soil water and groundwater in the middle and eastern NCP. Copyright © 2009 John Wiley & Sons, Ltd.     

1765-2010年黄河中游5-10月面降雨序列重建与特征分析

基于清代黄河流域水位志桩设置与报汛制度运作情况考证,梳理出清代陕州（陕县,今三门峡市）“万锦滩”水位志桩水尺记录数据,重建了黄河中游1765-2010年5-10月面降雨量变化序列。累积距平法分析显示,面降雨量变化具有较明显阶段性,3个降雨趋增阶段为1816-1863年、1902-1918年、1938-1989年;3个降雨趋减阶段为1765-1815年、1864-1901年、1919-1937年;Morlet小波分析显示,面降雨有5种时间尺度的周期特征,平均周期分别为72.7年,46.8年,30.3年,22.5年和11.2年;滑动t-检验显示面降雨序列存在1824-1826年、1856-1874年和1933-1937年3处突变时段最显著。通过与其他代用指标反映降雨序列及外部因子比对,在1810s、1840-1850s、1880-1900s、1920s、1970s及1990s等几个时段,各序列十年尺度变化趋势比较吻合,显示出基于历史文献和自然指标等不同代用资料重建结果基本一致,亦反映了历史气候变化研究中的不确定性特征。     

北京西山中生代火山岩中单斜辉石矿物化学及成因意义

本文对北京西山中生你火山岩中单斜辉石的矿物化学特点进行了研究,确定了矿物种属,计算了晶胞体积、密度和平均折射率。对单斜辉石－熔体平衡进行了判别,计算了平衡温度、压力和氧逸度,进而估算了岩浆房的深度。依据单斜辉石的成分和演化,结合岩石化学和地球化学特点,对火山岩的系列以及岩浆形成机制进行了讨论,探讨了岩浆活动的构造背景。     

大水沟碲矿中楚碲铋矿显微文像结构：交代成因新证据

大水沟楚碲铋矿的产状及其文像矿物形态既有普遍的“交代”现象,也有明显的“出溶”特征。文像黄铁矿与伴生或残余的磁黄匠矿成分的相似性,以及文像矿物在分布和成分上与溶动力实验以及理论模式的差异,表明形成显微文像结构的根本原因富碲、铋流体交代早期磁黄铁矿。楚碲铋矿及其显微文像结构的特征取决于交代环境的“封闭”程度：强度弱、无铁带出的交代形成具明显“交代”特征的楚碲铋矿;当交代强度大、环境封闭时,交代残余矿     

浙江铜山源水库美国大口胭脂鱼的年龄组成及生长

2002-2004年,在浙江衢州铜山源水库,对该库放养的美国大口胭脂鱼的生长情况进行了研究,结果表明,该水 库美国大口胭脂鱼的鳞片以环片的切割型为主要年轮特征．用刺网所捕的美国大口胭脂鱼渔获物中以Ⅱ、Ⅲ、Ⅳ龄个体为 主．体长和体重的关系式为：W=8．595×10~(-5)15 L~(2.662),Von Bertalanffy 生长方程的主要生物学参数：L_∞=36．54cm,W_∞= 1．245kg,K=0．6377,t_0=-0．261龄,体重生长的拐点年龄 t_1=1．92龄,拐点体重W_1=0．396kg．与池养鱼类生长情况相 比,铜山源水库的美国大口胭脂鱼生长较慢．