Geochemical, Sr–Nd and zircon U–Pb–Hf isotopic studies of Late Carboniferous magmatism in the West Junggar, Xinjiang: Implications for ridge subduction?

Voluminous granitic intrusions are distributed in the West Junggar, NW China, and they can be classified as the dioritic rocks, charnockite and alkali-feldspar granite groups. The dioritic rocks (SiO₂ = 50.4–63.8 wt.%) are calc-alkaline and Mg enriched (average MgO = 4.54 wt.%, Mg^# = 0.39–0.64), with high Sr/Y ratios (average = 21.2), weak negative Eu (average Eu/Eu = 0.80) and pronounced negative Nb–Ta anomalies. Their Sr–Nd and zircon Hf isotopic compositions ((⁸⁷Sr/⁸⁶Sr)_i = 0.7035–0.7042, ε_Nd(t) = 4.5–7.9, ε_Hf(t) = 14.1–14.5) show a depleted mantle-like signature. These features are compatible with adakites derived from partial melting of subducted oceanic crust that interacted with mantle materials. The charnockites (SiO₂ = 60.0–65.3 wt.%) show transitional geochemical characteristics from calc-alkaline to alkaline, with weak negative Eu (average Eu/Eu = 0.75) but pronounced negative Nb–Ta anomalies. Sr–Nd and zircon Hf isotopic compositions ((⁸⁷Sr/⁸⁶Sr)_i = 0.7037–0.7039, ε_Nd(t) = 5.2–8.0, ε_Hf(t) = 13.9–14.7) also indicate a depleted source, suggesting melts from a hot, juvenile lower crust. Alkali-feldspar granites (SiO₂ = 70.0–78.4 wt.%) are alkali and Fe-enriched, and have distinct negative Eu and Nb–Ta anomalies (average Eu/Eu = 0.26), low Sr/Y ratios (average = 2.11), and depleted Sr–Nd and zircon Hf isotopic compositions ((⁸⁷Sr/⁸⁶Sr)_i = 0.7024–0.7045, ε_Nd(t) = 5.1–8.9, ε_Hf(t) = 13.7–14.2). These characteristics are also comparable with those of rocks derived from juvenile lower crust. Despite of the differences in petrology, geochemistry and possibly different origins, zircon ages indicate that these three groups of rocks were coevally emplaced at ~ 305 Ma.A ridge subduction model can account for the geochemical characteristics of these granitoids and coeval mafic rocks. As the “slab window” opened, upwelling asthenosphere provided enhanced heat flux and triggered voluminous magmatisms: partial melting of the subducting slab formed the dioritic rocks; partial melting of the hot juvenile lower crust produced charnockite and alkali-feldspar granite, and partial melting in the mantle wedge generated mafic rocks in the region. These results suggest that subduction was ongoing in the Late Carboniferous and, thus support that the accretion and collision in the Central Asian Orogenic Belt took place in North Xinjiang after 305 Ma, and possibly in the Permian.     

胶州湾东北部海域生态环境污染状况研究

根据2004年5月和2005年5月两次对胶州湾东北部海域海水的盐度、pH、溶解氧、化学需氧量、无机氮、活性磷酸盐、铜、铅、锌、镉、多环芳烃和有机氯农药以及表层沉积物中有机碳、石油烃、硫化物、铜、铅、镉、汞、多环芳烃和有机氯农药测定结果,并结合2001年以来历史资料,对胶州湾东北部海域生态环境质量历史变化趋势进行了分析,该海域生态环境中除个别要素如活性磷酸盐、铅、镉、汞等重金属含量有所增加外,其他污染要素含量相对稳定且有下降趋势,2001—2005年该海域生态环境质量相对稳定,仅部分要素有加重趋势。     

多尺度生态资产遥感综合测量的技术体系

着重论述了如何建立多尺度生态资产遥感综合测量的技术体系，具体包括以下主要内容：①如何建立一整套生态资产遥感监测、野外抽样调查以及监测结果质量控制的技术标准与规范；②并在此基础上，设计出生态资产遥感测量的技术规程、主要研究内容以及野外抽样调查与检验方案；③通过建立生态资产遥感测量和野外抽样测量与检验的集成系统，实现系统的业务化运行。     

内蒙古喀喇沁旗金蟾山金矿床控矿断裂特征

金蟾山金矿位于内蒙古喀喇沁旗安家营子花岗岩体内的断裂中,矿区断裂构造分为东、西两个断裂群,以NNE向和近SN向脆性断裂为主,成群分布,控矿断裂形成于135～126Ma期间;成矿前表现为两组共扼的节理,成矿期近SN向和NNE向断裂、主断裂与派生断裂共同控矿。     

氧化亚铁硫杆菌水文地球化学作用实验初步研究

在某些地球化学环境中，微生物对水─岩相互作用有重要影响。本文通过氧化亚铁硫杆菌与硫化物相互作用试验，初步研究了氧化亚铁硫杆菌作用引起水─岩介质变化特征，分析了氧化亚铁硫杆菌水文地球化学作用的一些规律。     

Release of heavy metals during weathering of the Lower Cambrian Black Shales in western Hunan,China

Weathering of heavy metal enriched black shales may be one of the most important sources of environmental contamination in areas where black shales are distributed. Heavy metal release during weathering of the Lower Cambrian Black Shales (LCBS) in western Hunan, China, was investigated using traditional geochemical methods and the ICP-MS analytical technique. Concentrations of 16 heavy metals, 8 trace elements and P were measured for samples from selected weathering profiles at the Taiping vanadium ore mine (TP), the Matian phosphorous ore mine (MT), and Taojiang stone-coal mine (TJ). The results show that the bedrock at these three profiles is enriched with Sc, V, Cr, Co, Ni, Cu, Zn, Pb, Th, U, Mo, Cd, Sb, Tl, and P. Based on mass-balance calculation, the percentages of heavy metals released (in % loss) relative to immobile element Nb were estimated. The results show significant rates of release during weathering of: V, Cr, Co, Ni, Cu, Zn, U, Mo, Cd, Sn, Sb, and Tl for the TP profile; Sc, Cr, Mn, Co, Ni, Cu, Zn, Pb, Th, Cd, and Sn for the MT profile; and Sc, Mn, Co, Ni, Zn, Th, Cd, Sn, and Tl for the TJ profile. Among these heavy metals, Co, Ni, Zn, Cd, and Sn show very similar features of release from each of the three weathering profiles. The heavy metals released during weathering may affect the environment (especially topsoil and surface waters) and are possibly related to an observed high incidence of endemic diseases in the area.     

内蒙古中部二叠纪碱性花岗岩及其地球动力学意义

西伯利亚板块南缘白音乌拉－东乌珠穆沁旗带的碱性花岗岩（Ｒｂ－Ｓｒ年龄２７６－２８６Ｍａ）生成于张性的构造环境，较西伯亚板块同中朝板块之间晚泥盆世－早石炭世的碰撞事件晚约６０Ｍａ，属于造山后的Ａ型花岗岩，可作为造山作用结束的标志。但在中朝板块北缘晚石炭世－二叠纪只发育钙碱性的晚造山花岗岩，直到三叠纪才出现碱性正长岩。相邻两大板块边缘之间岩浆活动的非对称性可能是受板块间面积和质量差别的制约。     

一些有机物对Ph、Zn、Cu迁移与沉积作用的实验研究

根据一些有机物在成矿溶液中存在的可能性,作者相继就中性、酸性与碱性氨基酸,以及酒石酸在铅、锌、铜迁移与沉积过程中的作用,进行了模拟实验研究。结果表明,在从９０～２１０℃范围内,酸性氨基酸在热卤水中的存在,比中性和碱性氨基酸更有利于铅、锌、铜的活化、迁移。而酒石酸在热卤水中的存在,只在９０℃或更低时,才是铅、锌等金属活化、迁移的最佳温度条件。且无论哪种有机物在热卤水中的存在,随作用时间及温度的变化,不同金属的活化、迁移明显不同。这表明,金属与氨基酸或其它有机物形成的易溶络合物,其稳定性不仅与金属、氨基酸等有机物的种类有关,而且还受温度的显著影响。     

云南兰坪金满中生代沉积岩中的铜矿成矿作用

兰坪－思茅中新生代盆地沉积岩中产出一系列热液型铜矿床（矿点），以石英、铁白云石与含铜硫化物（包括黄铜矿、斑铜矿、黝铜矿和辉铜矿）为主，呈脉状产于砂岩、页岩中，而单独的黝铜矿、方解石和重晶石脉则产于底部碳酸盐岩中．红色碎屑岩中的浅色还原层内的细脉和裂隙中也具有铜矿化。矿石构造以角砾状、脉状最为发育，矿脉多位于褶皱与走向断裂破碎带的叠加部位。金满铜矿的Ｓｒ、Ｓ、Ｐｈ同位素证据、稀土元素地球化学及液体包裹体资料表明，成矿元素主要来自沉积岩层，合矿卤水属于盆地卤水，流来自于硫酸盐的还原作用及沉积硫化物的淋滤溶解作用。含矿流体是Ｈ。Ｏ－ＮａＣＩ～ＣＯ。体系卤水，成矿温度为１５０～３００Ｃ，流体盐度为５％～２０％ＮａＣＩ。据含ＣＯ２包裹体的测温资料估算成矿压力大于６Ｘ１０＇Ｐａ，相当于３ｋｍ深的静岩压力。根据铜矿床成因研究，笔者提出了含矿热卤水储备与突发成矿作用的成矿模式。成矿前，矿化卤水象石油天然气一样，首先集中到一定的构造部位，在构造活动期突然爆炸成矿。成矿期由３个阶段组成，即爆炸充填、渗透充填与改造阶段，热液活动主要在前两个阶段。