冀北西部银矿成矿地质条件

冀北西部地处西伯利亚板块，华北板块及太平洋板块接壤的三角地带，区域地质构造复杂，岩浆活动频繁，是成矿的有利地带，区内银矿资源丰富。区内银矿床可划分为岩浆热液、火山一次火山热液和层控三种矿床成因类型。     

应重视选用芳烃演化参数评价高演化碳酸盐岩

现被广泛应用的测定高演化碳酸盐岩成熟度指标的多项有机岩石学评价方法，各有其不同的局限性，应用效果并不理想。研究发现，可利用芳烃演化新参数来代替其它失效的分子参数来评价碳酸盐岩有机质。芳烃因其结构、组成的特殊性和稳定性，在高演化阶段与油气生成及煤源岩成熟度有着良好的相关性，具有成为高演化碳酸盐岩成熟度指标的基础。从生产实践的角度看，芳烃演化参数有特殊适用性及选取的可行性。     

层序地层学在油储勘查研究中的新思维

当前层序地层学面临的问题是不能充分证明所研究的层序具有等时性和可对比性。层序界面和体系域与固，液体矿产的成矿作用存在内在的，有机的成因联系。最大海泛面以上各体系 叠置可构成自生的生储盖组合；具有古喀斯特作用的高水位体系域的溶蚀孔洞和其上的暴露面为成矿流体的运移提供了通道，因此它们不仅是层控型金属矿产的储矿空间，而且也是最有利的储油构造的地层圈闭。     

当阳地区地震地质特征浅析

本区构造发展存在三个不同阶段，印支期为初始褶皱阶段；燕山期为逆冲推覆定型阶段；喜马拉雅期为改造与破坏阶段。其地质结构明显具有双重构造，构造反转和推覆滑税三大特征。区内地震反射特征与岩性组合有一定对应关系，本文首次尝试利用地震反射信息特征对沉积环境进行分析。     

滇黔桂地区中古生界油气地质条件及勘探选区

滇黔桂大部分地区属中国板块,在哀牢山—藤条河缝合带及昌宁—双江缝合带以西属青藏板块。前者自震旦纪至中三叠世沉积了一套海相台、盆序列的碳酸盐岩和碎屑岩;后者在二叠纪至侏罗纪早中期沉积了一套深海、半深海槽盆相地层。在海相沉积之后接受了陆相沉积,中生代盆地环特提斯洋分布,属南前陆盆地带。全区发育了众多的中—新生代盆地,对其中七个盆地进行了油气地质条件综合分析,提出了有利选区依次为:楚雄盆地、十万大山盆地、南盘江盆地、思茅盆地、绥江地区。     

Petrology of high-pressure granulites from the eastern Himalayan syntaxis

The eastern Himalayan syntaxis, situated at the eastern terminus of the Himalayas, is the least-known segment of the Himalayas. Recent research in this area has revealed that the syntaxis consists of the Gangdise, the Yarlung Zangbo, and the Himalayan units, each of which is bounded by faults. The Himalayan unit, the northernmost exposed part of the Indian plate, mainly contains amphibolite facies rocks, marked by the assemblages staurolite+kyanite+plagioclase+biotite+muscovite±sillimanite and garnet+amphibole+plagioclase, in the south; to the north, low- to medium-pressure granulite grade pelitic gneisses and marbles are present and are characterized by the assemblages garnet+sillimanite+K-feldspar+plagioclase or antiperthite+biotite+quartz±spinel±cordierite±orthopyroxene in gneisses, and anorthite+diopside±wollastonite and plagioclase+diopside+quartz+phlogopite+calcite in marbles. Within this unit, the Namula thrust system is a series of moderately north-dipping structures that displaced the granulite facies rocks southwards over the amphibolite facies rocks. High-pressure granulites occur as relics within these granulite facies rocks and contain garnet–kyanite granulite and garnet clinopyroxenite. The peak assemblage of the garnet–kyanite granulite includes garnet (core part)+kyanite+ternary feldspar+quartz+rutile. Sillimanite+garnet (rim part)+K-feldspar+ oligoclase+ilmenite+biotite and spinel+albite+biotite or spinel+cordierite±orthopyroxene, which are coronas around sillimanite and garnet, are retrograde products of this peak assemblage. Another peak assemblage includes very-high-Ca garnet (CaO 32–34 wt%, Alm₁₀±Grs_>80) and diopside (CaO 22–24 wt%), scapolite, meionite, quartz, and accessory Al-bearing titanite (Al₂O₃ 4–4.5 wt%). The diopside has kink bands. Partial or complete breakdown of Ca-rich garnet during post-peak metamorphism produced pseudomorphs and coronas consisting of fine-grained symplectic intergrowths of hedenbergite and anorthite. Thermobarometric estimates in combination with reaction textures, mineral compositions, and recent experimental studies indicate that these peak assemblages were formed at P=c. 1.7–1.8 GPa, T =c. 890 °C, and the retrograde assemblages experienced near-isothermal decompression to P=0.5±0.1 GPa, T =850±50 °C. The whole-rock compositions indicate that marble and pelite are plausible candidates for the protoliths. These facts suggest the following (1) sedimentary rocks were transported to upper-mantle depths and equilibrated at those conditions to form these high-pressure granulites, which were then emplaced into the crust quickly. During the rapid exhumation of these rocks, the earlier high-pressure assemblages were overprinted by the later low- to medium-pressure assemblages, that is, the high-pressure granulite belt formed in the syntaxis. (2) The Namula thrust system is an important tectonic boundary in the syntaxis, or even in the Higher Himalaya more generally.     

Experiments with Higdon's absorbing boundary conditions for a number of wave equations

Simulation of wave propagation for seismic purposes is usually restricted to a small portion of the earth. Artificial boundary conditions are required where the subsurface model is truncated. Absorbing boundaries should ensure that waves hitting the artificial boundaries are not reflected. The vast amount of literature on the subject suggests that “good” conditions have not been found, and only “reasonable” solutions exist. A cursory overview of existing and a few new ideas is presented that may guide the construction of suitable boundary conditions. Because the intended application of the boundary conditions was a high-order finite-difference code that runs on a parallel computer, we have restricted our attention to local boundary conditions. A fundamental problem in the design of accurate local boundary conditions is pointed out: accuracy is required to keep the amount of reflected energy small, but at the same time allows for growing low-frequency modes. We have settled for Higdon’s boundary conditions. Higdon proposes to include some damping to suppress the growing low-frequency modes. We show that third-order conditions provide acceptable results for the simple scalar wave equation and the acoustic equation. In the elastic case, an additional low-frequency growing mode may occur. This mode can be suppressed by using a dissipative boundary scheme and by increasing the amount of damping. The increase in damping results in an increase in the amount of reflected energy, which is larger than in the scalar case. Numerical experiments exhibit a reasonable performance, although some improvement would be useful, particularly in the anisotropic elastic case. This revised version was published online in July 2006 with corrections to the Cover Date.     

南京北郊低空污染气象条件若干特征

本文根据南京北郊大厂镇地区实测低空温风资料的统计分析,揭露了该区低空逆温、混合层顶高度、风向、风速、大气稳定度等的铅直分布规律和局地环流的某些特征。     

通化石家铺子金矿床地质特征及成因探讨

金矿床产于中元古界老岭群珍珠门组中,受北东向头道—金厂—通化断裂的次一级F_(210)断裂控制。矿石类型主要为褐铁矿型矿石及黄铁矿型矿石。金与黄铁矿关系密切,主要呈自然金出现。金来源于含金较高的珍珠门组第三段地层岩浆期后的矿液中。成因为岩浆期后热液迭加改造的层控破碎带蚀变岩型金矿床。     

浅成热液成矿系统模型研究评述

目前国内外矿床模型研究的一个明显发展势是研制成矿系统的地质成因模型，即建立具有一定的成因联系的不同矿种的矿系列成因模型。分析了近年来浅成热液矿床概念，分类、成模型式研究进展，评述了浅成热液矿床矿系统研究现状，并对我国此类矿床的研究提出建议。