最优化的矿物扩散地质速率计:北大别黄土岭麻粒岩缓慢冷却的证据

对北大别黄土岭麻粒岩中石榴子石进行了详细的电子探针工作，并根据一颗石榴子石的成分环带，建立了扩散模型并进行了数值模拟，结合最优化的方法，得到了极其缓慢的冷却速率0.1℃/a。从扩散动力学数值模拟的角度对大别山造山带的冷却速率进行了探索性研究。该结果表明，黄土岭麻粒岩在受麻粒岩相改造后经历的是一个极其缓慢、持续时间很长的冷却过程。     

东南极格罗夫山泛非期麻粒岩相变质作用

东南极格罗夫山主要由麻粒岩相高级变质岩和花岗岩类组成，其中变质岩以浅色和暗色含斜方辉石长英质片麻岩占主导地位，夹有少量镁铁质麻粒岩、变沉积岩和含方柱石钙硅酸盐岩。这些岩石一般都展示了平衡的矿物共生结构，但在镁铁质麻粒岩的单斜辉石中普遍发育斜方辉石(易变辉石)的出溶片晶。根据出溶辉石的重组分析获得麻粒岩相变质作用的峰期温度约为850℃，而浅色片麻岩中的石榴子石—斜方辉石—斜长石—石英组合给出的变质压力为0．61～0．67GPa。镁铁质麻粒岩中火成亚钙质普通辉石斑晶的保存表明格罗夫山地区可能只发育单一的泛非期高温麻粒岩相变质事件，岩石在高温变质之后经历了缓慢冷却过程，这主要归因于花岗质岩浆的板底垫托作用。     

0．7Ma以来的念青唐古拉山脉隆升过程——来自冰川剥蚀作用的证据

通过对念青唐古拉山冰碛地层划分及冰碛物同位素测年，发现最早一期冰碛物形成于0．7～0．6MaBP，指示自中更新世以来念青唐古拉山脉开始隆升，主峰地区发生了大规模的冰川剥蚀作用，形成了大面积分布的冰碛高平台；0．2～0．14MaBP念青唐古拉山又快速隆升，并堆积了刚刚伸出各大沟谷口的高侧碛；0．07～0．03MaBP念青唐古拉山再次小规模隆起，形成各大沟谷内的侧碛和终碛垄；0．01Ma BP还有小规模冰川活动。念青唐古拉山主峰地区的冰川剥蚀作用反映出的山脉隆升过程，可较好地与青藏高原的隆起过程相对比，它应是青藏高原隆升的响应。     

Carboniferous Post-collisional Rift Volcanism of the Tianshan Mountains, Northwestern China

The Tianshan Carboniferous post-collisional rift volcanic rocks occur in northwestern China as a large igneous province. Based on petrogeochemical data, the Tianshan Carboniferous post-collisional rift basic lavas can be classified into two major magma types: (1) the low-Ti/Y type situated in the eastern-central Tianshan area, which exhibits low Ti/Y (<500), Ce/Yb (<15) and SiO2 (43-55%), and relatively high Fe2O3T (6.4-11.5%); (2) the high-Ti/Y type situated in the western Tianshan area, which has high Ti/Y (>500), Ce/Yb (>11) and SiO2 (49-55%), and relatively low Fe2O3T (5.8-7.8%). Elemental data suggest that chemical variations of the low-Ti/Y and high-Ti/Y lavas cannot be explained by fractional crystallization from a common parental magma. The Tianshan Carboniferous basic lavas originated most likely from an OIB-like asthenospheric mantle source (87Sr/86Sr(t) ≈ 0.703-0.705, εNd(t) ≈ +4 to +7). The crustal contamination and continental lithospheric mantle have also contributed significantly to the formation of the basic lavas of the Tianshan Carboniferous post-collisional rift. The silicic lavas were probably generated by partial melting of the crust. The data of this study show that spatial petrogeochemical variations exist in the Carboniferous post-collisional rift volcanics province in the Tianshan region. Occurrence of the thickest volcanics dominated by tholeiitic lavas may imply that the center of the mantle-melting anomaly (mantle plume) was in the eastern Tianshan area at that time. The basic volcanic magmas in the eastern Tianshan area were generated by a relatively high degree of partial melting of the mantle source around the spinel-garnet transition zone, whereas the alkaline basaltic lavas are of the dominant magma type in the western Tianshan area, which were generated by a low degree of partial melting of the mantle source within the stable garnet region, thus the basic lavas of the western Tianshan area might have resulted from relatively thick lithosphere and low geothermal gradient.     

Rivers, chemical weathering and Earth's climate

We detail the results of recent studies describing and quantifying the large-scale chemical weathering of the main types of continental silicate rocks: granites and basalts. These studies aim at establishing chemical weathering laws for these two lithologies, describing the dependence of chemical weathering on environmental parameters, such as climate and mechanical erosion. As shown within this contribution, such mathematical laws are of primary importance for numerical models calculating the evolution of the partial pressure of atmospheric CO₂ and the Earth climate at geological timescales. The major results can be summarized as follow: (1) weathering of continental basaltic lithologies accounts for about 30% of the total consumption of atmospheric CO₂ through weathering of continental silicate rocks. This is related to their high weatherability (about eight times greater than the granite weatherability); (2) a simple weathering law has been established for basaltic lithologies, giving the consumption of atmospheric CO₂ as a function of regional continental runoff, and mean annual regional temperature; (3) no such simple weathering law can be proposed for granitic lithologies, since the effect of temperature can only be identified for regions displaying high continental runoff; (4) a general law relating mechanical erosion and chemical weathering has been validated on small and large catchments. The consequences of these major advances on the climatic evolution of the Earth are discussed. Particularly, the impacts of the onset of the Deccan trapps and the Himalayan orogeny on the global carbon cycle are reinvestigated. To cite this article: B. Dupré et al., C. R. Geoscience 335 (2003).     

昆仑山口西8.1级地震前青藏块体边界断层异常活动

系统分析了青藏块体边界断层的形变资料，研究了断层活动的动态过程及空间分布。结果表明，昆仑山口西8．1级地震前孕震影响范围达到青藏块体的周边地区；发震断层所在的构造带震前断层活动最为剧烈；加强对构造块体断层整体活动的宏观动态比较和分析，有助于判定未来强震发生的危险地段；震后应力将转移并集中到西秦岭构造带及其邻近地区。     

2001年11月14日昆仑山口西8.1级地震前地震活动性异常及其思考s

2001年11月14日在昆仑山口西发生了8.1级地震，震中位置为90.9E、36.2N．分析表明，8.1级地震前一些主要地震活动性异常都出现了，例如空区、条带、增强、平静和震群等，且与7级大震比较，这些前兆图象的演变具有类似的过程，所不同的是8.1级地震的前兆地震活动图象涉及的区域范围更大、地震震级更高，这为特大地震的前兆识别和预报提供了依据．最后回顾了对这次大震的粗略预测，并讨论了有关大震预测的某些问题．      

Mobility of heavy metals as a function of pH of samples from an overbank sediment profile contaminated by mining activities

Parts of the flood plains north of the Harz Mountains are contaminated with heavy metals, such as Pb, Cu, Zn and Cd derived from mining, which has been carried out in the Harz Mts. since the Middle Ages. It is important to know the mobility of the heavy metals in these overbank sediments in order to estimate the danger to the environment arising from this source. This paper deals with the effect of pH on heavy-metal mobility, using a constant-pH method. The investigations were carried out on an overbank sediment profile near Salzgitter Bad, north of the Harz Mts. The mobility of the heavy metals in the overbank sediment profile is described as a function of pH and depth. Besides the mobile heavy-metal fraction at a certain pH, the buffering capacity of the sediment at this pH must be taken into consideration. The different layers of the overbank sediment profile show distinct differences in buffering capacity and a natural pH harrier could be identified in the upper part of the profile. Therefore, to avoid increasing heavy-metal mobility the natural layering of the overbank sediment profile should not be disturbed. Two different kinds of desorption experiments at constant pH are also discussed, as well as the conversion of the heavy-metal species in the ore minerals into the species in the sediment.     

天山泥石流灾害的形成条件和过程特点

泥石流是天山主要自然灾害之一， 天山泥石流按触发因素可以分为暴雨型泥石流和冰川型泥石流两类。目前天山泥石流主要对效能运输造成灾害在部分地点对厂矿企业和居民点造成灾害，天山泥石流的形成和发生有其特点，掌握其形条件和过程特点有利于减轻自然灾害。     

铅—试铁灵络合物吸附波及溴化十六烷基三甲基铵增敏效应的研究

在０３０ｍｏｌ／ＬＨＡｃ介质中，Ｐｂ（Ⅱ）与７＿碘＿８＿羟基喹啉＿５＿磺酸（试铁灵，Ｆｅｒｏｎ）的络合物于－０５４Ｖ（ｖｓ．ＳＣＥ）产生一尖锐的极谱波，加入溴化十六烷基三甲基铵（ＣＴＭＡＢ）显著增敏，可使极谱波增高约４倍。峰电流与Ｐｂ（Ⅱ）浓度在９６×１０－９～４８×１０－６ｍｏｌ／Ｌ呈良好的线性关系，检出限为４８×１０－９ｍｏｌ／Ｌ。用多种电化学方法研究了该极谱波的性质及电极反应机理表明，络合物组成比为ｎＰｂ（Ⅱ）∶ｎＦｅｒｏｎ＝１∶１，极谱波为吸附波，峰电流由中心离子Ｐｂ（Ⅱ）还原产生，电子转移数为２。试验了多种离子对峰电流的影响，拟定的方法用于矿样分析，结果与原结果相符。