西南天山二叠纪中酸性侵入岩的地质学和地球化学：岩石成因和构造背景

选择3个典型岩体,即位于西南天山东段的拜城县英买来岩体和位于西段阔克萨岭区的川乌鲁岩体、巴雷公岩体（为了对比,也选择了位于塔里木盆地西北缘的麻扎山岩体）,进行了岩石学和地球化学研究。结果表明,这些岩体具有不同的特点。英买来岩体为黑云母花岗岩和二云母花岗岩,具有高的SiO2含量,弱过铝,高的Sr同位素初始值（约0.710）和负的εNd(t)值（-4～-6）,属于S—A型之间的过渡类型。麻扎山岩体由正长岩组成,属于碱性岩,微量元素标准化图解和其他岩体明显不同的是没有明显的Nb和Ta的负异常。川乌鲁岩体是一个由3个不同期次岩石组成的杂岩体,主体为正长岩-二长岩,地球化学特征显示是由基性岩浆和酸性岩浆不同程度混合形成的。位于同一构造区的巴雷公岩体则与川乌鲁岩体中的花岗斑岩的地球化学特征相似。综合岩石学和地球化学特征推测,南天山东段的英买来岩体是地壳熔融的结果,没有任何地幔物质加入的地球化学信息,西段的阔克萨岭地区酸性岩浆的形成则可能是来自于幔源底侵的基性岩浆导致薄的地壳发生熔融的结果。麻扎山岩体则完全是不同构造背景的产物,有可能与发生在塔里木盆地的二叠纪大规模的岩浆活动有关。因此,二叠纪岩浆活动的性质主要受地壳成分和结构的控制。     

南祁连山前区中生代晚期古构造特征的研究

南祁连山前区可以分为露头和盆地区两个不同的大地构造单元,本区晚中生代构造活动强烈,控制了新生代的沉积过程和现今中生界残余层序的分布。本文提出了均匀平板状沉积体后期的构造变形可以利用古地质图以及高精度残余地层厚度的变化规律判断古构造带的分析方法,并且对于研究区中生代晚期的古构造特征进行了分析。露头区主要利用古地质图分析方法,研究区集中在赛什腾山—埃姆尼克山北缘的鱼卡和红山地区。盆地区主要利用中生界残余厚度图的分析方法,研究区集中在赛什腾山—埃姆尼克山南侧的赛什腾南部凹陷和马海凸起地区。通过这4个地区古构造特征的研究,提出南祁连山前区中生代晚期在区域性隆升的背景下,形成了一系列古构造带,古构造活动的特点是形成北西—北北西走向的背斜和向斜构造,这些褶皱的波长为15～20 km,为中尺度规模。同时指出,中国西部多数地区均缺失上白垩统,暗示着当时的中亚地区存在一个广阔的晚白垩世古高原。     

三论花岗岩按照Sr-Yb的分类:应用

在"再论"中我们提出了花岗岩按照Sr-Yb分类的新标志(张旗等,2010a),本文进一步讨论该分类的应用。文中举了国内外许多实例(包括柴达木、北祁连、内蒙古、松潘-甘孜、大别、太行、华北古元古代和华南新元古代以及土耳其、俄罗斯、巴西、刚果、波西米亚、意大利等),着重讨论了花岗岩Sr和Yb含量与其形成压力和深度的关系,指出本分类最重要的地球动力学意义在于与其形成的深度有关,并在一定条件下与其产出地区的地壳厚度有关。例如应用本方法分析华北克拉通古元古代花岗岩,很难得出该带在古元古代发生过碰撞的结论,华北克拉通是否分为东西两块也需要重新认识。又如对华南新元古代花岗岩的分析表明,华南地块内部在新元古代时地壳较薄,但是,与Rodinia大陆的裂解似乎无关。文中还对花岗岩与成矿的关系进行了讨论,提出成矿与压力有关的概念。如金铜与地壳厚度大的埃达克型和喜马拉雅型花岗岩有关,钨锡与地壳厚度薄的南岭型花岗岩有关,而不论矿床是什么类型的,只要它们与花岗岩有关,必定受矿液源区深度的控制,要么是在加厚地壳的地球动力学背景下,要么是在地壳减薄的地球动力学背景下。花岗岩无比复杂,我们用Sr和Yb两个元素对花岗岩重新进行了分类,只是一个探索性的尝试,问题肯定不少,需要广泛的实践的检验,需要深入的实验研究的检验,需要理论的探讨,需要经过一系列否定-肯定-否定的过程,才能逐渐臻于完善。     

洞室声波测试及数据处理技术

洞室声波测试是为获得准确、详细的岩体物理学参数,而在洞室内进行的一系列声波测试方法,通过计算和观察岩体声波速度的量值变化和分布规律,对岩体工程特性进行了评价,并了解洞壁岩体因施工开挖引起的松弛状况,还可以与岩体变形试验成果结合建立起动静态弹性模量之间的对比关系。     

基于对数指数型蓄水容量曲线改进新安江模型

原新安江模型利用一个经验函数即抛物线来考虑下垫面张力水蓄水容量空间分布不均,其数学和物理基础不明确.基于地形指数和土地利用覆被类型与包气带厚度的相关关系可以推求出张力水蓄水容量曲线,与传统概化出的曲线不同,为更好地描述流域张力水蓄水容量空间分布,在此提出用一种新的函数——对数指数函数来代替新安江模型中的抛物线以改进新安...     

利用石香肠恢复能干层原始厚度的等面积法

在恢复岩层古环境、计算岩石流变学参数时常需要岩层的原始厚度.利用在褶皱地区伴生的肿缩石香肠可恢复岩层的原始厚度.经过沉积、压实作用以后,岩层压实率趋近最终压实率,岩石中矿物颗粒骨架基本上保持不变,则岩层体积保持不变.褶皱一般是受到垂直岩层或平行岩层作用力而形成的,肿缩石香肠在褶皱轴向(b轴)上变形通常很微小,根据体积不变的假设,则石香肠体在褶皱横向剖面(ac面)上变形前后的面积应是相等的,以此来恢复岩层的原始厚度.为了求解肿缩石香肠横向剖面面积,对其边界进行拟合、积分,发现它相当于一些梯形面积之和.运用此方法进行模拟实验并对铁山地区进行计算,并把计算结果与肿缩石香肠的最大厚度比较,发现它更能反映真实情况.     

均匀倾斜层状地层中地震波球面扩散补偿方法研究

在分析地层深度、炮检距以及地层倾角变化对球面扩散补偿因子影响的基础上,总结了不同因素对补偿因子影响的趋势,以及资料处理中常规球面扩散补偿方法的应用条件．实际应用效果表明,该方法能更加合理的保证不同深度地震信息能量的均衡程度,提高资料的可信度。     

Effects of sand-mulch thickness on soil evaporation during the freeze–thaw period

Control of evaporation from seasonally frozen soil is an important method for alleviating water shortages in arid and semi-arid areas. To investigate the inhibition of soil evaporation by sand and the major factors that influence soil evaporation, a series of field experiments with five sand-mulch thicknesses (0 cm, bare soil [BS], 1 cm [T1], 2 cm [T2], 3 cm [T3] and 4 cm [T4], with an average diameter of 1 mm) were conducted during the freeze–thaw period in Northern China. Soil evaporation characteristics in the three freeze–thaw stages were revealed and the major factors influencing soil evaporation were analysed using grey correlation analysis. The results showed that the cumulative soil evaporation decreased with increasing sand-mulch thickness during the freeze–thaw period, and only small differences in soil evaporation were observed between the T3 and T4 treatments. The reduction in soil evaporation under different sand-mulch thicknesses was 19.2–62.6% in the unstable freezing stage (P1), 2.0–28.3% in the stable freezing stage (P2) and 4.8–20.4% in the thawing stage (P3). In P1, solar radiation was a major factor influencing soil evaporation in all treatments and vapour pressure was a major factor in the sand-mulch treatments, and the influence of relative humidity on soil evaporation decreased in the T4 treatment. During the coldest P2, solar radiation was lowest so that relative humidity and wind speed became the more dominant influence factors on soil evaporation in all treatments, and surface soil water content was a major factor in the sand-mulch treatments. In P3, average air temperature and solar radiation were major factor influencing soil evaporation in all treatments and vapour pressure was a major factor in the BS and T1 treatments, whereas water surface evaporation was the major factor in the T2, T3 and T4 treatments. The results suggest that the addition of sand mulch in agricultural fields may be a beneficial practice to reduce water stress in arid and semi-arid areas.     

An anisotropic elastic‐decohesive constitutive relation for sea ice

Thermodynamic growth or melt and mechanical redistribution due to lead opening or ridge formation shape the thickness distribution of the Arctic ice cover and impact the overall strength of pack ice. Specifically, the deformation and strength of ice are not isotropic but vary with the thickness and lead orientation. To reflect these facts, we develop an anisotropic, elastic‐decohesive constitutive model for sea ice together with a model to describe an oriented, ice thickness distribution. The tight connection between the mechanical response and the thickness distribution is an improvement over a previous model that only depended on the average ice thickness. The model describes mechanical responses anisotropically in both the elastic and failure regimes. In the elastic regime, the constitutive relation implicitly reflects strong and weak directions of the pack ice depending on the distribution of thin ice (including open water) and thicker ice (e.g., multi‐year ice or ridges). In the failure regime, the model predicts both failure initiation and the lead orientation. Evolution from initial failure to complete failure when traction‐free crack surfaces are formed is also modeled. Crack or lead width is determined during the evolution. Various examples of failure surfaces are presented to describe the behavior of modeled ice when the thickness distribution varies. The model predictions are also illustrated and compared with previous modeling efforts by examining regions of ice under idealized loading. Copyright © 2015 John Wiley & Sons, Ltd.     

Quantifying ice storage in upper Indus river basin using ground-penetrating radar measurements and glacier bed topography model version 2

Ice reserve estimates is a fundamental prerequisite for water resources management. We selected the UIB (upper Indus river basin) as study area because it contains the most abundant mid-latitude glaciers outside the polar region, however, the ice reserve estimates remain unclear due to the harsh topography. In this study, we validated the parameters of the GlabTop2 model (Glacier Bed Topography version 2) using the ice thickness measured by GPR (ground-penetrating radar) and compared the “GPR-measured ice thickness and ice bed elevation” versus “the estimated results obtained from GlabTop2.” Integrated with IDW (inverse distance weighted) interpolated results of glaciers of various sizes, a reasonable parametric scheme (τ = 120 kPa and f = 0.8) of GlabTop2 was applied on vast amounts of glaciers in the UIB region. The GlabTop2 estimates indicated that the ice thickness of the UIB varied from 0 to 736.0 ± 110.0 m, with an average value of 74.5 ± 11.2 m. A significant spatial heterogeneity exists in the sub-basins. The Shyok, Shigar and Hunza that contain the most abundant ice reserve. Lesser quantities are stored in the Western Himalaya and Hindu Kush ranges, which account for 11.3 % and 6.7 % of the total ice reserve in the UIB, respectively. A total volume of 1162.4 ± 175.1 km³ of glacier can be converted to 1046.2 ± 157.6 Gt ice reserve; this is 13.6 times the annual average discharge obtained from the outlet of the Besham hydrological station. We aim to present estimates that can provide the baseline information for glaciology study of the Indus river.