吉林省兰家金矿原生地球化学特征

兰家金矿床位于大黑山条垒的金银多金属成矿带中。具有矽卡岩型、破碎带蚀变岩型及细脉浸染型三种类型的金矿体,矿床的形成与晚三叠世泉眼沟序列南泉眼单元的石英闪长岩的多次活动有密切的关系。Ａｕ、Ａｇ、Ｂｉ是成矿元素的特征组合,其原生地球化学特征可做为矿床评价及指导找矿的依据。     

《国内外金银矿床四十例》

《国内外金银矿床四十例》已由核工业北京地质研究院情报室(北京1401信箱)编辑出版发行。此书是在收集了大量国内外金银矿床资料的基础上,经过认真选题、整理、编辑加工而成的。书中系统而全面地介绍了国内外有名的40个金银矿床的基本情况,其中有国内各种类型金银矿床28个,国外有名的大型及超大型金银矿床12个。在每个矿床实例中,都详细介绍了     

桂东南金银矿床成矿规律与成矿模式

根据桂东南金银矿床成矿地质条件，典型金银矿床的硫、氢、氧、铅同位素、稀土元素、矿物包裹体流作组份和成矿物理化学条件，提出了桂东南金银矿床的混合岩化─岩浆热液型和变质─岩浆热液型的成因类型，并建立了桂东南金银矿床的成矿模式。即地槽发展时期形成矿源层，变质─混合岩化作用促进金银组份活化迁移与初始富集，剥离作用使金银组份再次迁移富集；燕山期构造─岩浆作用成矿。     

桂东南金银矿床成矿规律与成矿模式

根据桂东南金银矿床成矿地质条件，典型金银矿床的硫、氢、氧、铅同位素、稀土元素、矿物包裹体流体组份和成矿物理化学条件，提出了桂东南金银矿床的混合岩化－岩浆热液型和变质－岩浆热液型的成因类型，并建立了桂东南金银矿床的成矿模式。即地槽发展时期形成矿源层；变质－混合岩化作用促进金银组份活化迁移与初始富集；剥离作用使金银组份再次迁移富集；燕山期构造－岩浆作用成矿。     

朝鲜半岛南部金银矿床的矿物学和地球化学

南朝鲜的大多数金银矿床产于前寒武纪的花岗片麻岩及与之密切相关的侏罗纪花岗岩中。这些矿床即所渭的“鲜朝式”金银矿床属高温或中温热液型矿床。其在地质和矿物特征方面与日本的奥伊阿(Ooya)矿床类似。朝鲜式金银矿床和日本奥伊阿矿床的含金银矿物均为银金矿和辉银矿,与之伴生的硫化物矿物主要是黄铁矿和毒砂,其次有少量的黄铜矿和方铅矿。     

论自然金银矿物Au、Ag含量的标型意义

本文对自然金银矿物的Au、Ag含量的标型意义做了比较全面的论述。自然金银矿物Au、Ag含量的标型意义主要由以下三方面来反映:(1)矿床中自然金银矿物的组合特点;(2)自然金银矿物内部Au、Ag含量的均匀性;(3)自然金银矿物的成色。对以上三方面所反映的矿床成因、矿床形成条件、形成时代及矿床类型等的意义分别作了探讨。对于指导矿床深部的评价及寻找矿金的源区等有实用意义。     

山门金银矿床重砂异常特征及找矿意义

本文通过对山门金银矿床自然重砂矿物的系统研究,揭示了山门金银矿床自然重砂异常的分布特征,优选出具有重要找矿指示作用的重砂矿物,并确定标型矿物组合,结合地质特征建立山门金银矿床的自然重砂找矿模式,为找矿预测提供重要依据。     

浙江遂昌—龙泉地区金银矿床中石英和黄铁矿的标型特征

本文着重研究了浙江遂昌—龙泉地区金银矿床中石英和黄铁矿的标型特征,可作为本区金银矿床找矿勘探的矿物学标志。     

浅成热液金银矿床的沸腾-酸化成矿模式研究

近年来,对与中一新生代陆相火山活动有关的浅成热液金银矿床的成矿模式,如环太平洋全球性火山带金银成矿带内的金银矿床的成矿模式深受重视,对浅成热液金银矿床的沸腾-酸化成矿模式尤为赞赏。该模式是Reed和Spycher(1985,1989)等通过对现代活动的地热系统的金银矿化特征的详细观察与研究,并结合模拟实验而提出来的。     

辽宁红石砬子金银矿床中金银矿物标型特征及成因意义

从金银矿物形态、金矿物成色、微量元素等方面对红石砬子金银矿床金银矿物标型进行了研究,对其成因标志意义进行了探讨.认为金矿物以银金矿为主,赋存状态为晶隙金、裂隙金和包体金.金矿物成色为334~813,平均为664.微量元素以含Bi、Cu、Sb相对高为特征,反映出该金银矿床成因类型是浅成中低温热液矿床.     

Condensed sections: Terminology,types, and accumulation conditions

Condensed sections (CS) are abnormally thin but nominally complete sections embracing large stratigraphic intervals. They are subdivided with regard to sedimentation rate into CS (at sedimentation rate of 0.5–1 cm/ka) and ultracondensed sections (with a sedimentation rate <0.5 cm/ka), which can be both deep-water and shallow-water types. The mechanisms of CS accumulation include mechanical, chemical, biotic condensation, and nondeposition. Their combinations allow one to suggest some models of CS accumulation: (1) fast and (2) slow sea level rise and/or its low-amplitude fluctuations; (3) sea level drop; (4) global warming and (5) global cooling.     

基于信息量、逻辑回归及其耦合模型的滑坡易发性评估研究:以青海沙塘川流域为例

滑坡易发性定量评估是预测滑坡发生空间概率的重要手段,基于统计分析原理的评估方法目前在国内外应用最为广泛,且不同评估方法的对比研究逐渐成为热点。以青海沙塘川流域黄土梁峁区为例,剖析了信息量模型和逻辑回归模型在滑坡易发性评估中的优越性和局限性,并探索提出基于二者的耦合模型。考虑坡度、坡向、起伏度、岩性、与干流距离、与支流距离和植被指数等7个影响因素,对比分析了基于信息量、逻辑回归及二者耦合模型的滑坡易发性评估的技术流程及结果。3种模型的成功率分别为:耦合模型成功率(78. 9%)>信息量模型成功率(71. 8%)>逻辑回归模型成功率(70. 8%)。在沙塘川流域黄土滑坡的易发性评估中,信息量和逻辑回归模型的表现基本相当,但信息量-逻辑回归耦合模型的成功率明显提升。该研究结果可为黄土高原区滑坡易发性定量评估提供借鉴。     

Degradation of rock fracture asperities in unloading,reloading, and reversal

Among the constitutive models for rock fractures developed over the years, Barton's empirical model has been widely used. Although Barton's failure criterion predicts peak shear strength of rock fractures with acceptable precision, it has some limitations in estimating the peak shear displacement, post‐peak shear strength, dilation, and surface degradation. The first author modified Barton's original model in order to address these limitations. Barton proposed his model for degradation of fracture asperities in unloading, reloading, and shear displacement reversal based on just one cyclic direct shear test. In this study, a database of results of 18 cyclic direct shear tests available in the literature was collected and analyzed. Modifications were made to Barton's original model (in terms of fracture cyclic shearing) to make it consistent with the modified model proposed by the first author. Copyright © 2010 John Wiley & Sons, Ltd.     

云南保山核桃坪铅矿床地球化学特征及其成矿模式与找矿模型

核桃坪铅锌矿区容矿地层地球化学特征研究表明上寒武统核桃坪组下段、沙河厂组下段和保山组上段可能是Cu矿化的矿源层;核桃坪组中段和沙河厂组可能是Zn矿化的矿源层;核桃坪组中段可能是Pb矿化的矿源层.此外,上寒武统整体上以强烈富集(K≥5)Bi、B,富集(K≥1.2)Sb、As、W、Sn为特征;Bi、Sb、As、B等金属、半金属和非金属矿化剂元素在容矿地层中的普遍富集可能为在后期热液成矿作用过程中捕获成矿元素、导致成矿物质巨量堆积,最终形成工业矿床奠定了基础.基性岩脉以强烈富集(K≥5)Au、Ag、Cu、Pb、Zn、W、As、Sb、Bi、F为特征,富集元素的种类和矿石具有一致性.综合各类控矿因素,并结合稳定同位素和成矿流体特征等认为,矿床是在晚寒武世特定的沉积条件下形成矿源层和矿化剂的基础上,再经后期岩浆热液作用叠加,并在有利的构造部位形成的层控型热液矿床;成矿作用具多期、多阶段,成矿物质具多来源的特点.在上述基础上,初步建立了该矿床的成矿模式和找矿模型.     

长白山地区新生代火山岩的岩石化学及Sr、Nd、Pb同位素地球化学研究

通过主元素、稀土元素、Sr、Nd、Pb同位素地球化学特征并结合板块俯冲模式来讨论长白山地区新生代火山岩系的形成和演化。大部分样品都进入上地幔Sr演化范围,具低Sr高~(87)Sr/~(86)Sr特点;∑Nd介于-2.3—+2.9之间;不同岩性熔岩的Pb同位素组成变化不大。主元素、REE模式和同位素的资料都证实区内火山岩是源自上地幔的同源岩浆分异演化而成,并有地壳物质的混染。     

浙江省永嘉县滑坡灾害危险性区划

永嘉县是浙江省滑坡灾害发生频繁的区县之一,其滑坡受地质、地形和人类工程活动等因素的影响。本文根据永嘉县滑坡灾害分布情况,选择了影响滑坡分布的主要因素,将各种因子归一化处理后转换成相同分辨率的定量数据,选择了逻辑回归分析模型和信息量模型进行滑坡灾害危险性评价。在逻辑回归模型中,利用SPSS软件,通过逐步回归分析筛选出影响滑坡的最直接的因子,计算出各个因子的回归系数,得到逻辑回归方程,据此编制了危险性预测分区图。在信息量模型中,通过MAPGIS软件及其二次开发的信息量模型,对永嘉县滑坡灾害进行了危险性区划,并依信息量法的结果编制了该区的危险性预测分区图。两种方法所编制的危险性分区图中高危险区和中危险区重合率达到了87%,具有很高的一致性,起到了相互验证的作用,为滑坡的有效防治提供了依据。最后根据"云娜"台风期间永嘉县实际灾害发生情况的资料分析,新灾害点绝大部分落在危险性预测区中的高危险区,表明模型的预测准确率很高。     

团结沟金矿床地质模型

矿床地质模型是综合信息找矿模型的基础。本文从团结沟金矿床地质特征入手，分析了团结沟金矿床的控矿地质条件，探讨矿床的成因，进而建立起团结沟金矿床的矿床地质模型。     

Flooding and its relationship with land cover change,population growth,and road density

Bangladesh experiences frequent hydro-climatic disasters such as flooding.These disasters are believed to be associated with land use changes and climate variability.However,identifying the factors that lead to flooding is challenging.This study mapped flood susceptibility in the northeast region of Bangladesh using Bayesian regularization back propagation(BRBP)neural network,classification and regression trees(CART),a statistical model(STM)using the evidence belief function(EBF),and their ensemble models(EMs)for three time periods(2000,2014,and 2017).The accuracy of machine learning algorithms(MLAs),STM,and EMs were assessed by considering the area under the curve-receiver operating char-acteristic(AUC-ROC).Evaluation of the accuracy levels of the aforementioned algorithms revealed that EM4(BRBP-CART-EBF)outperformed(AUC＞90％)standalone and other ensemble models for the three time periods analyzed.Furthermore,this study investigated the relationships among land cover change(LCC),population growth(PG),road density(RD),and relative change of flooding(RCF)areas for the per-iod between 2000 and 2017.The results showed that areas with very high susceptibility to flooding increased by 19.72％between 2000 and 2017,while the PG rate increased by 51.68％over the same period.The Pearson correlation coefficient for RCF and RD was calculated to be 0.496.These findings highlight the significant association between floods and causative factors.The study findings could be valuable to policymakers and resource managers as they can lead to improvements in flood management and reduction in flood damage and risks.     

绍兴土地信托流转的运行机制、实施困境与发展策略

作为一种重要的土地流转模式,土地信托流转曾极大地提高了土地流转的效率,而时至今日其运作推广却陷入了困局。本文通过对绍兴土地信托流转的研究,分析了绍兴土地信托流转的运行机制和实施困境,同时在新的土地流转发展趋势下,为绍兴土地信托流转模式提出发展策略。     

A model for dilatation, densification, and static liquefaction of loose sands

Utilizing basic balance laws of saturated granular media, a theoretical model for describing the phenomena of dilatation and densification of dry sand, as well as the increase of pore water pressure of saturated sand during shear loading, is developed. An expression for the free-energy function of loose sands is postulated, and the problem of static shearing of a sand sample is analyzed. Predictions of the model for pore water pressure are compared with those obtained experimentally for dry pluviated and moist vibrated samples of fine Ottawa sand and solid-glass beads and discussed.