不同初始饱和度红砂岩冻融后物理力学性质研究

对不同初始饱和度红砂岩冻融循环前后进行物理及力学试验研究,探讨初始饱和度对红砂岩冻融损伤的影响。本文设定红砂岩试样初始饱和度为20%、40%、60%、80%、100%,冻融次数设定为20次,对冻融前后试样分别测定质量、纵波波速以及进行单轴压缩试验。试验结果表明：1）冻融后不同初始饱和度红砂岩的物理性质发生变化,纵波波速降低、质量减小,但变化程度不同;2）随饱和度的增大,试样经冻融后峰值强度和弹性模量均呈降低趋势,但只有饱和度大于60%时,降低趋势较明显。本文研究为寒区隧道及地下工程建设以及岩土地质灾害监测与治理提供理论依据和试验基础。     

天然气水合物体系的相平衡及甲烷溶解度计算

海洋环境中天然气水合物的形成除了合适的温压条件外,还必须有充分的甲烷供给.本文介绍了甲烷-水体系的甲烷饱和溶解度、水合物体系中甲烷水合物溶解度计算方法.在气-液二相平衡甲烷饱和溶解度计算中,关键在于状态方程的选择和合适的混合规则的运用,Duan的计算模型在温度、压力和盐度变化上都具有很大的适用性,且易于应用.在含水合物的相平衡体系中,在已知组分和假定可能存在相的前提下,可利用模拟退火算法优化总吉布斯自由能,确定是二相还是三相体系,并求解甲烷水合物溶解度.在海水环境下盐的存在使平衡发生移动,利用德拜—休克尔理论或Pitzer电解质溶液理论校正盐度对于海水活度的影响,求解海水环境中甲烷水合物溶解度.基于气-液二相平衡理论的K-K方程,在临近水合物生成条件下实验或计算确定亨利常数等参数后,可计算三相平衡甲烷水合物溶解度,且简单易用.     

西风槽与副高相互作用的暴雨过程动热力场结构特征分析

利用常规气象观测、自动气象站加密观测、NCEP/NCAR(1°×1°,逐6 h)再分析以及FY 2C卫星云图等资料,分析了2007年8月15—18日发生在山东的一次暴雨过程中,西风槽与副热带高压(以下简称副高)相互作用三个阶段的热力、动力场结构特征。结果表明:整个过程先后经历了副高西进切变线缓慢西移、横槽南压副高减弱和横槽转竖副高南撤三个阶段,三个阶段的共同特征是中低层有切变线和θ_(se)锋区;700 hPa有低空急流;产生暴雨的对流云团具有后向传播特征,生命史中多次发生合并。三个阶段的不同点是:(1)副高西进过程中,锋区随高度向北倾斜,坡度小,切变线和θ_(se)锋区均为后倾,为典型的暖锋降水。暴雨区范围大,强度均匀,位于850 hPaθ_(se)锋区与暖脊的交界处的水汽辐合中心附近。饱和区宽广,伸展高度高。低层气旋性辐合、切变线辐合、锋面抬升是触发暴雨的动力机制,低空急流是暴雨增强机制。(2)副高减弱过程中,干冷空气分别从低层和中层侵入θ_(se)暖脊,θ_(se)锋区随高度先向北后向南,呈交错倾斜现象,坡度大,为典型的强对流降水,上升运动最为激烈。暴雨区范围小,强度大,分布不均,位于θ_(se)暖脊垂直方向轴线附近。饱和区狭窄,伸展高度高。锋面抬升运动是触发对流性强降水的主要动力机制,对流层中层干冷空气入侵是强降水的增强机制。(3)副高南撤过程中,θ_(se)锋区随高度向南倾斜,坡度大,呈前倾特征,为典型的高空槽降水。暴雨区狭长分散,强度弱,位于850 hPa切变线上、θ_(se)暖舌靠近锋区一侧。饱和区狭窄,伸展高度低。低层切变线辐合抬升是触发强降水动力机制,中层干侵入是降水增强机制。     

金川与黑山铜镍硫化物矿对比及找矿预测

分析研究甘肃金川与甘肃肃北黑山铜镍硫化物矿床,认为两者存在明显相似,矿床成因都属岩浆熔离矿床,局部都发现有贯入型特富矿石。根据在两地的实际工作情况,作者对黑山矿田含矿超基性岩体的形成与空间展布规律进行新的研究判断。     

鄂尔多斯盆地延安地区山西组山2段储层可动流体赋存影响因素分析

山2段是鄂尔多斯盆地延安地区致密砂岩气生产的重要层段,目前对其流体赋存规律认识明显不足。因此在铸体薄片、扫描电镜、X射线衍射、高压压汞、恒速压汞、核磁共振测试的基础上,分析该储层可动流体的赋存特征及其影响因素。结果表明:山2储层主要为岩屑石英砂岩和岩屑砂岩,溶蚀孔和晶间孔为主要储集空间,粒间溶孔显著发育。山2储层可动流体饱和度为34.74%～91.83%,平均为69.94%,T2谱多为双峰态,呈左低右高型。储层孔隙度、渗透率、孔隙类型、孔喉特征及胶结物影响可动流体饱和度。孔隙为可动流体提供主要空间,平均孔隙半径越大,平均喉道半径越大,孔喉比越小,可动流体饱和度越高。硅质含量越高,粒间孔保存越好,可动流体饱和度越高。铁方解石含量越高,孔隙破坏越明显,可动流体饱和越低。高岭石含量较高,长石溶孔及晶间孔发育较好,有利于流体流动,可动流体饱和度也较高。     

天然水CaCO_3侵蚀量与沉淀量的计算

天然水ＣａＣＯ３侵蚀量与沉淀量的计算是岩溶地球化学研究中的一个重要问题，本文在指出有关文献对这一问题的处理存在严重问题的同时，提出了天然水ＣａＣＯ３侵蚀量与沉淀量计算的新方法。该方法以水溶液相对ＣＳＣＯ３饱和度的计算为基础，对ＣａＣＯ３溶解或沉淀所引起的水溶液ｐＨ值、组分的活度系数以及水溶液中各组分存在形式含量的变化统一地作了考虑，且区分开放系统与封闭系统两种不同的情况分别进行了计算。实际水样的计算结果表明，计算中若不考虑上述的种种变化，则计算结果的误差将是相当大的。     

Mineralogical,petrological, and geochemical studies of the Limahe mafic–ultramatic intrusion and associated Ni–Cu sulfide ores,SW China

The Limahe Ni–Cu sulfide deposit is hosted by a small mafic–ultramafic intrusion (800 × 200 × 300 m) that is temporally associated with the voluminous Permian flood basalts in SW China. The objective of this study is to better understand the origin of the deposit in the context of regional magmatism which is important for the ongoing mineral exploration in the region. The Limahe intrusion is a multiphase intrusion with an ultramafic unit at the base and a mafic unit at the top. The two rock units have intrusive contacts and exhibit similar mantle-normalized trace element patterns and Sr–Nd isotopic compositions but significantly different cumulus mineralogy and major element compositions. The similarities suggest that they are related to a common parental liquid, whereas the differences point to magma differentiation by olivine crystallization at depth. Sulfide mineralization is restricted to the ultramafic unit. The abundances of sulfides in the ultramafic unit generally increase towards the basal contacts with sedimentary footwall. The δ ³⁴S values of sulfide minerals from the Limahe deposit are elevated, ranging from +2.4 to +5.4‰. These values suggest the involvement of external S with elevated δ ³⁴S values. The mantle-normalized platinum-group element (PGE) patterns of bulk sulfide ores are similar to those of picrites associated with flood basalts in the region. The abundances of PGE in the sulfide ores, however, are significantly lower than that of sulfide liquid expected to segregate from undepleted picrite magma. Cr-spinel and olivine are present in the Limahe ultramafic rocks as well as in the picrites. Mantle-normalized trace element patterns of the Limahe intrusion generally resemble those of the picrites. However, negative Nb–Ta anomalies, common features of contamination with the lower or middle crust, are present in the intrusion but absent in the picrites. Sr–Nd isotopes suggest that the Limahe intrusion experienced higher degrees of contamination with the upper crust than did the picrites. The results of this study permit us to suggest that the parental magma of the Limahe intrusion was derived from picritic magma by olivine fractionation and contamination in a staging chamber at mid-crustal levels. Depletion of PGE in the sulfide ores in the Limahe intrusion is likely due to previous sulfide segregation of the parental magmas in the staging chamber. Sulfide mineralization in the Limahe intrusion is related to second-stage sulfide segregation after the fractionated magmas acquired external S from pyrite-bearing country rocks during magma ascent to the Limahe chamber. The abrupt change in mineralogical and chemical compositions between the ultramafic unit and the overlying unit suggests that at least two separate pulses of magma were involved in the development of the Limahe intrusion. We propose that the Limahe intrusion was once a wider part of a dynamic conduit that fed magma to the overlying subvolcanic dykes/sills or lavas. The ultramafic unit formed by the first, relatively more primitive magma, and the mafic unit formed by the second, relatively more fractionated magma. Immiscible sulfide droplets that segregated from the first magma settled down with olivine crystals to form the sulfide-bearing, olivine-rich rocks in the base of the intrusion. The overlying residual liquids were then pushed out of the chamber by the second magma. Critical factors for the formation of an economic Ni–Cu sulfide deposit in such a small intrusion include the dynamic petrologic processes involved and the availability of external sulfur. The Limahe deposit reminds us that small, multiphase, mafic–ultramafic intrusions in the region should not be overlooked for the potential of economic Ni–Cu sulfide deposits.     

Review on Researches of Aragonite Saturation State in the Southern Ocean:A Key Parameter of Southern Ocean Acidification

The Southern Ocean is a strong sink for atmospheric CO₂, making it especially vulnerable to ocean acidification (OA). The aragonite saturation state (Ω_arg) of seawater has been used as an index for the estimation of OA, which plays a critical role in evaluating the living environment of marine calcified organisms. However, it is very difficult to perform the studies of OA and Ω_arg in the Southern Ocean due to its harsh climate. Therefore, in order to better understand the OA and its further influences, the advances of Ω_arg studies were summarized in the oceans surrounding the Antarctica. Significant spatial and temporal variations of surface seawater Ω_arg are demonstrated in the Southern Ocean. In general, the surface seawater Ω_arg shows a lower value in the off-shore areas than in the open oceans. And, Ω_arg also exhibits a strong seasonal cycle with a higher value in summer than in winter. The distributions of Ω_arg in vertical water column generally present a declining tendency from surface to bottom. In addition, the shoaling of Ω_arg horizon at high latitude could be attributed to the ventilation and upwelling of deep waters in the Southern Ocean. There are many factors that could impact the Ω_arg in the Southern Ocean, including sea ice melting, sea-air CO₂ exchange, biological activities and hydrological processes, etc. Finally, the future changes and key scientific problems of OA in the Southern Ocean are proposed.     

连续局部阈值分割的阴影检测方法

遥感图像中通常存在大量的阴影,阴影会对图像分割、目标识别造成一定的影响,阴影检测是阴影去除的基础。针对传统Tsai算法准确度上不足,提出了一种改进方法。首先,采用chuang所提出的方法定制了新的比例图,通过对定制比例图进行全局阈值分割将输入图像分为候选阴影点与非阴影点;再对大致阴影图中的每一个候选阴影区进行迭代分割处理来从候选阴影点中挑选出真正的阴影点;剩下的每一个候选阴影点进行fine-shadow判断处理。实验证明,改进算法可以提高阴影检测的准确性。