西天山喇嘛苏铜矿成矿斑岩的岩石学、地球化学特征及成因探讨

位于西天山别珍套-科古琴晚古生代岛弧西段的喇嘛苏铜矿床是区内最大的铜矿床,与成矿作用有着密切关系的斑岩体为英云闪长斑岩、花岗闪长斑岩,是同源岩浆分异演化的产物,且花岗闪长斑岩可能属于岩浆演化晚期的产物。本区成矿斑岩的主量、微量元素和Sr-Nd同位素地球化学特征表明,其富集大离子亲石元素,而相对亏损高场强元素,出现了较为明显的Ta、Nb负异常,初始锶同位素ISr和εNd(t=390Ma)值分别为0.7072～0.7076和-0.32～0.17,显示壳幔混合源的特征,利用Sr和Nd同位素估算其源区物质约有50%来源于地壳。岩石地球化学特征指示了其为典型钙碱性火山弧花岗岩,暗示其形成于大陆弧环境。结合区域地质背景,推测本区成矿斑岩是在洋壳俯冲作用下发生部分熔融,交代原先的地幔楔,并混合了部分下地壳的物质,经历分离结晶作用的产物,其形成可能与晚古生代准噶尔洋板块向南的俯冲作用有关。结合东西天山的成矿斑岩的地球化学特征对比研究,岩浆源区的差别可能导致不同类型斑岩型矿床的形成,斑岩型铜矿床的形成较斑岩型钼矿床可能有更少的地壳物质贡献。     

Emission line widths of an asymmetric bowshock inside a cloud of dust

A model is presented that explains the anomalous emission line widths in the Herbig-Haro object HH 1 in terms of emission from a lop-sided bowshock and scattering by surrounding dust.     

Relationships between molecular bacterial diversity and chemistry of groundwater in the Wairarapa Valley,New Zealand

Groundwater plays an important role in New Zealand water supplies and hence monitoring activities are conducted regularly. Most monitoring programmes aim to evaluate groundwater chemistry and almost completely overlook the microbial component in this ecosystem. In our present study, the bacterial community structure of groundwater in the Wairarapa Valley was examined using the terminal restriction fragment length polymorphism (T-RFLP), and relationships between bacterial community structure and groundwater chemistry, aquifer confinement and groundwater usage were explored. In addition, the results from this study were compared with a previous T-RFLP survey of the same area in an attempt to detect changes in bacterial community structure over time. The data obtained suggested that bacterial community structure was related to groundwater chemistry, especially to redox conditions. Species composition showed minimal variation over time if groundwater chemistry remained unchanged. These findings reflect the potential of using bacterial communities as biological indicators to evaluate the health of groundwater ecosystems. We suggest that it is important to include this type of broad bacterial diversity assessment criteria into regular groundwater monitoring activities.     

南天山川乌鲁碱性杂岩体的岩石学和地球化学特征及其岩石成因

位于中国南天山西侧阔克萨彦岭一带的川乌鲁碱性杂岩体,与该区川乌鲁铜金多金属矿床有着直接的成因联系,该杂岩体由早期的辉长岩—闪长岩岩、主期的二长岩—正长岩和晚期的正长花岗斑岩脉组成,各期岩石在矿物组成和化学成分上有明显的变化。从早到晚,SiO2含量增加,变化范围是50.52%～70.64%;全碱含量先增后减,在SiO2含量小于61.69%时,随SiO2含量增加而增加,而当SiO2含量大于61.69%时,与SiO2含量负相关。在AR-SiO2图解上,大多样品落入碱性区间,在A/CNK-A/NK图解上表现出由准铝质向过碱性演化的趋势。微量元素表现为大离子亲石元素相对高场强元素富集,Rb、Ba、Th、Sr等元素的相对富集和Nb、Ta、P、Ti等元素的负异常。稀土元素表现为轻稀土相对富集的特征,其(La/Yb)N为14.13～25.09,具有Eu的正异常或极微弱的Eu负异常。一些元素比值的线性关系暗示了该杂岩体为岩浆混合成因,基性岩浆的源区为富水的岩石圈地幔,而酸性岩浆是中下地壳中性火成岩在含饱和水条件下部分熔融的产物。这些性质指示川乌鲁杂岩体是在后碰撞拉张环境中由岩石圈地幔熔融的基性岩浆的底侵作用导致地壳的熔融以及后期的岩浆混合作用有关。     

Low-Degree Low-Order Solar p Modes As Seen By GOLF On board SOHO

Data recovered from the GOLF experiment on board the ESA/NASA SOHO spacecraft have been used to analyze the low-order low-degree solar velocity acoustic-mode spectrum below =1.5 mHz (i.e., 1n9,l2). Various techniques (periodogram, RLAvCS, homomorphic-deconvolution and RLSCSA) have been used and compared to avoid possible biases due to a given analysis method. In this work, the acoustic resonance modes sensitive to the solar central region are studied. Comparing results from the different analysis techniques, 10 modes below 1.5 mHz have been identified.     

About the rotation of the solar radiative interior

In the modern era of helioseismology we have a wealth of high-quality data available, e.g., more than 6 years of data collected by the various instruments on board the SOHO mission, and an even more extensive ground-based set of observations covering a full solar cycle. Thanks to this effort a detailed picture of the internal rotation of the Sun has been constructed. In this paper we present some of the actions that should be done to improve our knowledge of the inner rotation profile discussed during the workshop organized at Saclay on June 2003 on this topic. In particular we will concentrate on the extraction of the rotational frequency splittings of low- and medium-degree modes and their influence on the rotation of deeper layers. Furthermore, for the first time a full set of individual |m|-component rotational splittings is computed for modes ℓ≤4 and 1<ν<2 mHz, opening new studies on the latitudinal dependence of the rotation rate in the radiative interior. It will also be shown that these splittings have the footprints of the differential rotation of the convective zone which can be extremely useful to study the differential rotation of other stars where only these low-degree modes will be available.     

Mixed Caledonian appinite magmas: implications for lamprophyre fractionation and high Ba-Sr granite genesis

Ach'Uaine Hybrid appinites represent a rare example of lamprophyric magmas that were demonstrably exactly contemporaneous with felsic differentiates, preserved within a suite of minor, hypabyssal intrusions emplaced at the end of the Caledonian orogeny in northern Scotland. Numerous small stocks, bosses and dykes show outcrop-scale relationships characteristic of mingling between lamprophyric and syenitic magmas, and are commonly cut by sharp-sided granite veins. The mafic rocks are characterised by Ni and Cr abundances and MgO sufficiently high to signal derivation from a mantle source within which radiogenic ⁸⁷Sr/⁸⁶Sr and nonradiogenic ¹⁴³Nd/¹⁴⁴Nd ratios require significant time-integrated incompatible element enrichment. This is manifest in high Ba, Sr and light REE abundances and incompatible element ratios in the derived magmas directly comparable with those of high Ba-Sr granitoids and related rocks. Quantitative major element, trace element, radiogenic and stable isotope modelling is consistent with early fractionation of clinopyroxene and biotite, accompanied by minor crustal assimilation, having driven the evolving lamprophyric magma to cogenetic syenite. Subsequent derivation of granite required a major change to feldspar-dominated crystal fractionation with continued, still minor contamination. The elemental and isotopic characteristics of the granitic terminus are so similar to high Ba-Sr granitoids both locally and worldwide, that these too may have had large mantle components and represent significant juvenile additions to the crust. Received: 26 September 1995 / Accepted: 5 June 1996     

Solar Wind Forecasting with Coronal Holes

An empirical model for forecasting solar wind speed related geomagnetic events is presented here. The model is based on the estimated location and size of solar coronal holes. This method differs from models that are based on photospheric magnetograms (e.g., Wang–Sheeley model) to estimate the open field line configuration. Rather than requiring the use of a full magnetic synoptic map, the method presented here can be used to forecast solar wind velocities and magnetic polarity from a single coronal hole image, along with a single magnetic full-disk image. The coronal hole parameters used in this study are estimated with Kitt Peak Vacuum Telescope He I 1083 nm spectrograms and photospheric magnetograms. Solar wind and coronal hole data for the period between May 1992 and September 2003 are investigated. The new model is found to be accurate to within 10% of observed solar wind measurements for its best 1-month period, and it has a linear correlation coefficient of ∼0.38 for the full 11 years studied. Using a single estimated coronal hole map, the model can forecast the Earth directed solar wind velocity up to 8.5 days in advance. In addition, this method can be used with any source of coronal hole area and location data.