新疆尉犁蛭石矿中金云母—蛭石的间层结构研究

利用单晶片定向样品法测定了7个金云母-蛭石间层矿物样品的X射线衍射谱,计 算了底面反射的偏差系数和层结构因子。结果表明,所研究的样品可分为金云母-蛭石间层结构 和金云母与金云母-蛭石间层结构的分结型间层结构。金云母-蛭石的1∶1间层结构对于给出一 个新的矿物名称具有足够的交替规则性。对于给定的1∶1规则间层结构模型,层结构因子的实 验值与计算值非常吻合。进而,将这种规则间层结构矿物定义为水金云母。     

异类矿物结构基元层间层矿物及墨铜矿的研究

本文提出了“异类矿物结构基元层间层矿物”这一新概念，从五个方面限定了其含义，扩展了“间层矿物”的内涵。对其典型矿物墨铜矿进行了Ｘ射线，电子探针和高分辨透射电镜的初步研究，取得了一些新认识，墨铜矿在ｃ方向有序，重复周期为１１．４５Ａ，在ａ，ｂ方向无序，不存在超晶胞。     

一种三八面体缘泥石／皂石1：1规则间层矿物（绿间皂石）的初步研究

在湖北恩施利川地区的三叠系中统巴东组钙质砂质粘土岩及砂质泥质岩中，产出一 种褐灰色粘土矿物。通过X射线粉末衍射、红外、热分析、化学分析及电镜观察等测试研究，各 项实验数据证明该粘土矿物是三八面体绿泥石与三八面体皂石1:1规则间层矿物(绿间皂石)。自 然风干样和各种化学处理样的OOl衍射数据，都具育良好的整数倍关系。风干样001衍射的标准偏 差δ=0.1007，波动系数υc= 0.347。d060=1.531A, b0=9.19A，cosinβ=29.05A。并计算出了 该矿物的化学结构式。     

一种白云母/蒙皂石1:1规则间层矿物的初步研究

在湖北随县长岭地区变钠长辉绿岩与绢云母千枚岩接触带中,产出一种青灰色粘土矿物。经X射线衍射、红外、热分析、电镜观察及化学分析等方法研究,证明该矿物是一种二八面体白云母与二八面体蒙皂石的1:1规则间层粘土,(K_2O含量达到4.97%)。风干样的00l衍射具有良好的整数倍关系,δ=0.059,VC=0.239,d_(060)=1.503,a_0=5.20,b_0=9.02,c_0sinβ=24.70并依据化学分析值计算出该矿物的化学结构式。     

一种三八面体绿泥石/皂石1:1规则间层矿物(绿间皂石)的初步研究

在湖北恩施利川地区的三叠系中统巴东组钙质砂质粘土岩及砂质泥质岩中,产出一种褐灰色粘土矿物。通过X射线粉末衍射、红外、热分析、化学分析及电镜观察等测试研究,各项实验数据证明该粘土矿物是三八面体绿泥石与三八面体皂石1:1规则间层矿物(绿间皂石)。自然风干样和各种化学处理样的00l衍射数据,都具有良好的整数倍关系。风干样00l衍射的标准偏差δ=0.1007,波动系数vc=0.347。d_(060)=1.531,b_0=9.19,c_0sinβ=29.05。并计算出了该矿物的化学结构式。     

砂岩型铀矿床中SiO2/Al2O3比值与含矿性的关系研究:以库捷尔太和乌库尔其铀矿床为例

对库捷尔太和乌库尔其铀矿床进行了详细的层间氧化带的分带研究,在此基础上分析了主要元素Si,Al,Fe在层间氧化带各亚带中的迁移规律。研究表明,被认为稳定元素的So,Al在砂岩层间氧化过程中具有明显的变化规律：Si在氧化带具迁出特征,并随氧化作用的减弱而迁出的份额有规律的减少;而Al的地球化学行为则相反。不同的SiO2／Al2O3比值能够反映层问氧化带的含矿性。     

Crystallisation of sodium sulfate: supersaturation and metastable phases

Crystallisation of sodium sulfate solutions by evaporation under controlled climatic conditions has revealed the existence of crystalline hydrated sodium sulfate salts not previously reported. The sodium sulfate phase crystallising and the concentration of the solution at the point of crystallisation depends on the climatic conditions (temperature and evaporation rate). During the rehydration of the anhydrous sodium sulfate phase, thenardite, another previously unreported phase was formed prior to the nucleation of the stable phase, mirabilite Na₂SO₄ · 10H₂O. The addition of organic inhibitors changes both the crystallisation and the rehydration behavior in this system.     

Geochemical barriers: theory and practical applications

Geochemical barriers are zones in the Earth's crust with sharp physical or chemical gradients and they are often associated with concentrations of elements, sometimes to the extent of forming ore deposits. Four fundamental classes of geochemical barriers have been identified: (1) mechanical; (2) physico-chemical; (3) biochemical; (4) anthropogenic.Mechanical barriers are the simplest class and placer deposits are a good example. Physico-chemical barriers (the dominant class) are formed in zones characterized by sharp changes in the intensity of certain physico-chemical parameters of waters; tables of observed and predicted element associations have been prepared and these can be used to identify element concentrations which depend principally on the properties of waters. Biochemical barriers are specifically related to element concentrations brought about through reactions associated with life on Earth, for example, the accumulation of trace elements in effects are one variety. Although barriers consisting of combinations of several classes can occur, the main emphasis of this paper is on physico-chemical barriers with respect to ore deposits, soil geochemistry and groundwaters.     

Clay smear: Review of mechanisms and applications

Clay smear is a collection of fault processes and resulting fault structures that form when normal faults deform layered sedimentary sections. These elusive structures have attracted deep interest from researchers interested in subsurface fluid flow, particularly in the oil and gas industry. In the four decades since the association between clay-smear structures and oil and gas accumulations was introduced, there has been extensive research into the fault processes that create clay smear and the resulting effects of that clay smear on fluid flow. We undertake a critical review of the literature associated with outcrop studies, laboratory and numerical modeling, and subsurface field studies of clay smear and propose a comprehensive summary that encompasses all of these elements. Important fault processes that contribute to clay smear are defined in the context of the ratio of rock strength and in situ effective stresses, the geometric evolution of fault systems, and the composition of the faulted section. We find that although there has been progress in all avenues pursued, progress has been uneven, and the processes that disrupt clay smears are mostly overlooked. We highlight those research areas that we think will yield the greatest benefit and suggest that taking these emerging results within a more process-based framework presented here will lead to a new generation of clay smear models.     

查干凹陷下白垩统砂岩储层碳酸盐胶结物成岩期次及形成机理

通过矿物学、岩石学和地球化学方法,分析了查干凹陷下白垩统巴音戈壁组碎屑岩储层中多期碳酸盐胶结物的特征及成因机理。结果表明,根据碳酸盐胶结物的组分和结构,从矿物学和成岩序列的角度,可划分出三期胶结物类型,分别是Ⅰ期泥晶方解石、Ⅱ期含铁方解石,以及Ⅲ期的铁方解石、白云石及少量铁白云石。碳氧同位素研究表明,Ⅰ期泥晶方解石胶结物形成于常温常压中,主要从过饱和的碱性湖水介质中析出,形成于早成岩阶段A期,早于压实期,对孔隙的形成起到保存作用;Ⅱ期铁方解石形成于早成岩阶段B期-中成岩阶段A期,受控于埋藏过程中的水岩作用影响,其中的碳酸根来源于有机酸脱羧产生的CO_2,而Ca~(2+)和Fe~(3+)来自长石类颗粒的溶解和黏土矿物的转化,该期胶结物主要充填在残余原生粒间孔和各类次生溶孔中,对储层以破坏作用为主;Ⅲ期碳酸盐胶结物主要形成于中成岩阶段B期,成岩环境由弱酸向弱碱性转化,黏土矿物转化释放Mg~(2+)和Fe~(3+),其中Fe~(3+)被烃类还原成低价铁,为Ⅲ期含亚铁碳酸盐胶结物提供了充足来源,该期胶结物与Ⅱ期胶结物类似,对储层形成也属于"破坏型成岩作用"。     

Thermodynamic model of formation of carbonates and uranium mineral phases in lakes Namshi-Nur and Tsagan-Tyrm (Cisbaikalia)

The Tazheran lakes are located compactly in the small Tazheran steppe area. Their bottom sediments are predominantly various calcite-dolomite carbonates, and their waters are rich in uranium. The studies have shown that the main process in these lakes is chemogenic carbonate precipitation with the participation of carbon dioxide formed through the bacterial destruction of organic matter. For thermodynamic modeling of the composition of bottom sediments, we chose two lakes with different basic parameters. Calculations were made for the 15-component heterogeneous system H₂O-Na-Ca-Mg-K-Sr-Ba-Si-Al-Cl-C-S-Fe-U-Mn including particles in the solution, minerals, and gases at 25 °C and 1 bar. As starting information, we used the obtained analytical data on the natural composition of waters and bottom sediments. The results show that calcite-dolomite carbonates are predominant in the bottom sediments and the destruction of organic matter results in reducing conditions. This confirms the hypothesis of the formation of mineral phases of U(IV) during diagenetic processes in the bottom sediments of the studied lakes.     

Impact of solid second phases on deformation mechanisms of naturally deformed salt rocks (Kuh-e-Namak,Dashti, Iran) and rheological stratification of the Hormuz Salt Formation

Viscosity contrasts displayed in flow structures of a mountain namakier (Kuh-e-Namak - Dashti), between ‘weak’ second phase bearing rock salt and ‘strong’ pure rock salt types are studied for deformation mechanisms using detailed quantitative microstructural study. While the solid inclusions rich (“dirty”) rock salts contain disaggregated siltstone and dolomite interlayers, “clean” salts reveal microscopic hematite and remnants of abundant fluid inclusions in non-recrystallized cores of porphyroclasts. Although the flow in both, the recrystallized “dirty” and “clean” salt types is accommodated by combined mechanisms of pressure-solution creep (PS), grain boundary sliding (GBS), transgranular microcracking and dislocation creep accommodated grain boundary migration (GBM), their viscosity contrasts observed in the field outcrops are explained by: 1) enhanced ductility of “dirty” salts due to increased diffusion rates along the solid inclusion-halite contacts than along halite–halite contacts, and 2) slow rates of intergranular diffusion due to dissolved iron and inhibited dislocation creep due to hematite inclusions for “clean” salt types Rheological contrasts inferred by microstructural analysis between both salt rock classes apply in general for the “dirty” salt forming Lower Hormuz and the “clean” salt forming the Upper Hormuz of the Hormuz Formation and imply strain rate gradients or decoupling along horizons of mobilized salt types of different composition and microstructure.     

Using estimated thermodynamic properties to model accessory phases: the case of tourmaline

Accessory phases and minor components in minerals are commonly ignored in thermodynamic modelling. Such an approach seems unwarranted, as accessory phases can represent a significant element reservoir and minor components can substantially change their host mineral's stability field. However, a lack of thermodynamic data prohibits assessment of these effects. In this contribution, the polyhedron method is used to estimate the thermodynamic properties of tourmaline, a common and widespread accessory phase, stable over a range of P–T–X conditions. The polyhedron method allows Δ H , S , V , C _P and V _m ( T , P ) properties to be estimated from a linear stoichiometric summation over the fractional properties of its polyhedron constituents. To allow for estimates of tourmaline, fractional thermodynamic properties for B^III and B^IV polyhedra were derived. Mixing contributions to molar volume were evaluated and symmetrical mixing parameters derived for Al-Mg, Al-Fe and Al-Li interaction on tourmaline's Y-site and T-site Al-Si interaction. Evaluation of the estimated properties using experimental and natural equilibria between tourmaline and melts, minerals and hydrothermal fluids, shows that reliable semi-quantitative results are obtained. The boron contents in fluids coexisting with tourmaline are calculated to within an order of magnitude of measured content, and where anchor-points are available, agreement improves to within a factor of 2. Including tourmaline in petrogenetic modelling of metamorphic rocks indicates that its presence leads to disappearance of staurolite and garnet, among others, and modifies the X _Mg of coexisting phases, in line with observations on natural rocks.     

潍北油田储层的成岩作用及成岩相划分

潍北油田位于山东省潍坊市北部,主要含油层系为古始新统孔店组,储层埋藏深。岩石类型主要为长石砂岩、岩屑砂岩、岩屑长石砂岩或长石岩屑砂岩等近源沉积岩类。成岩作用类型主要包括压实作用、胶结作用和次生溶蚀作用,其中压实作用是使储层原生孔隙度迅速变差的主要因素。油田孔店组砂岩储层可以划分为两个成岩阶段,五个成岩亚期。不同的成岩亚期发育不同的成岩作用类型。在成岩作用研究的基础上,笔者引入成岩相和成岩综合系数概念。成岩综合系数可以定量表征各种成岩作用的综合效应。利用视压实率与视胶结率作交会图,结合成岩综合系数与孔隙度,可以将孔店组储层划分为六种成岩相,其中以弱压实中胶结的DRF1型储集性为最好,中压实强胶结的DRF4型储集性最差。潍北油田孔店组储层主要属中压实中胶结的DRF3型,其次是孔二中亚段发育的强压实中胶结的DRF5型与孔一下亚段发育的弱压实中胶结的DRF1型,局部出现其它三种类型的成岩相。     

甘肃合作市阿什加金矿床特征及找矿前景分析

阿什加金矿位于西秦岭夏河—合作断裂带北部,区内成矿条件优越。该矿是近年来新发现的一金矿床,处于岗岔至阿什加矿集区,对其进行分析研究,可为区内综合分析和地质勘查工作提供参考与对比。矿区现已探获8条金矿体,平均金品位3.03×10^-6。矿体受地层岩性、构造和岩浆岩控制,北西向层间构造为成矿热液的运移提供了通道和沉淀的场所,并控制矿体的产出和规模,在其变化段易形成工业矿体。褐铁矿、黄铁矿、辉锑矿和毒砂与金矿化关系密切,金主要以包裹金形式赋存于其中,金矿化的富集与蚀变的强度和硫化物含量呈正相关关系。通过总结分析矿床基本地质特征,并结合岗岔—阿什加矿集区成矿特征,认为在矿区深边部仍具较好的找矿前景。     

Combination of single and sequential chemical extractions to study the mobility and host phases of potentially toxic elements in airborne particulate matter

Risk assessment of metals associated to airborne particulate matter (PM) has usually been based on the analysis of their total concentrations, which is a poor indicator of metal mobility. Chemical fractionation processes may provide an additional level of information, however, chemical complexity and small sample sizes do not allow to combine several extraction methods. Additionally, analysing the metal concentrations during the extractions exceptionally provides restricted information about metals’ speciation. To overcome these limitations we collected total suspended particulate matter (TSP) samples from the air filters placed in the air supply channel of methane-heated turbines of thermal power stations which allows collecting large amounts of TSP materials. Additionally, we combined single and sequential chemical extractions in which not only the concentrations of potentially toxic elements (PTE) (Cd, Cr, Cu, Ni, Pb, Zn) but also that of the major chemical components (Al, Ca, Fe, K, Mg, Mn, Na, P, S, Ti) were analysed. Our aims were to study these metals’ mobility and speciation through the study of their association to major chemical components.Accumulation of the studied PTEs in the TSP material suggests moderate contamination for Ni, Cd and Cr whereas a heavy one for Cu, Zn and Pb. Three groups of these PTEs could be distinguished based on their mobility. The highly mobile Zn and Cd (large ratios of water and weak acid soluble fractions) can be considered as especially harmful elements to environment. The moderately mobile Pb and Cu (large ratios of reducible and oxidizable fractions, respectively) may potentially have a negative effect on the environment, whereas the immobile Cr and Ni cannot be expected to pose a serious risk. Based on the statistical evaluation of extraction data, the potential phases for Zn and Cu are presented by metal-sulphates, -nitrates, -chlorides, -carbonates and -hydroxides, as well as sorbed forms. Lead primarily hosted by metal-carbonates and sorbed forms, as well as by -hydroxides, whereas Cu by organic matter. Finally, Cr and Ni are mostly incorporated into very resistant phases, most probably by magnetite or other resistant metal-oxides.Combination of single and sequential extractions, as well as that of the analysis of not only the target elements but also the major chemical components were found to be a very effective tool to study the host phases of PTEs in the TSP material. The necessity for relatively large sample amounts for such analyses could be fulfilled using special sampling methodology; however, obvious disadvantages of this kind of sampling must be taken into account when resulted data are evaluated.     

Central Atlantic Igneous Province: Origin and mechanisms of formation

The paper considers various aspects of the formation of the Central Atlantic Igneous Province. Generation and eruption of enormous bodies of basic magmas over a short time interval (a few million years) are explained by the accumulation of thermal energy beneath the continental lithosphere. The thermal energy was transferred by heated matter or fluid flows from the lower mantle along separate channels or permeable zones and accumulated beneath the continental lithosphere of Pangea over a long period of time (tens of millions of years) over a vast area. The large thickness ofthe lithosphere hindered melting. A change in the geodynamic regime with the onset of the breakdown of Pangea resulted in extension, formation of linear permeable zones, local decompression, and, as a consequence, in generation and ascent of huge magma bodies along extended linear tectonically weakened zones. The homogeneity of igneous rocks is explained by the short time interval favorable for magma generation, when all the stored thermal energy had been exhausted.     

Nitrogen-heterocyclic compounds in meteorites: significance and mechanisms of formation

Samples of the Murchison (C2), Murray (C2) and Orgueil (C1) carbonaceous meteorites were analyzed for nitrogen-heterocyclic compounds using gas chromatography, cation and anion exclusion liquid chromatography and mass spectrometry. The purines adenine, guanine, hypoxanthine and xanthine were identified in formic acid extracts of all samples, in concentrations ranging from 114–655 ppb. Purines have not previously been found in the Murray meteorite and adenine. hypoxanthine and xanthine have never simultaneously been detected in meteorite extracts. All four biologically significant purines, as well as the pyrimidine uracil have now been identified in these meteorites. A number of other, previously reported N-heterocyclic compounds such as certain hydroxypyrimidines and s-triazines could not be detected in any of the extracts. Laboratory data indicated that both these classes of compounds may be formed from structurally simple precursors (such as guanylurea in the case of s-triazines) during the extraction and analysis of meteorite extracts.We find that the suite of N-heterocyclic compounds identified in meteorites do not, at present, permit a clear distinction to be made between mechanisms of synthesis such as the Fischer-Tropsch type and other candidates. Secondary reactions and conversions in meteorite parent bodies, of HCN and other nitriles produced by Miller-Urey type reactions as well as by Fischer-Tropsch type reactions, must also be considered.     

塔里木盆地北部奥陶系油气相态及其成因分析

塔里木盆地北部地区奥陶系是最重要的勘探层系,油气资源丰富;同时油气相态复杂多样,既有凝析气藏、正常油藏,也有稠油油藏、沥青等。通过对油气藏形成演化与保存过程的系统分析,结合油气地球化学和流体包裹体等分析数据,发现油气相态的多样性与油气多期次充注与次生蚀变作用有关。提出塔北隆起的东部奥陶系存在三期油气充注过程,分别发生在加里东运动晚期-海西早期、海西运动晚期、喜马拉雅运动晚期,原油主要来源于中、上奥陶统烃源岩,天然气主要来自与寒武系烃源岩有关的液态烃的裂解;塔北隆起的中西部奥陶系的油气充注主要发生在海西运动晚期。塔北奥陶系油藏形成以后,经历了三期明显的调整改造过程:海西早期构造抬升导致志留-泥盆系遭受剥蚀,东部源自寒武系油气的古油藏遭受破坏,形成沥青;三叠系沉积前的晚海西运动,使得奥陶系生源的油藏大范围遭受降解稠化;晚喜山期,来自于满加尔坳陷的天然气自东向西充注,致使隆起东部早期形成的油藏发生强烈的气侵改造,形成次生凝析气藏。而中西部奥陶系油藏在三叠系沉积前遭受降解稠化后,一直处于沉降深埋过程,油藏得到有效保存;由于成藏时间较早,轻质组分散失较多,气油比极低,油质较稠。研究认为,油气相态的多样性主要受晚海西期构造运动的抬升造成的生物降解作用和喜马拉雅晚期构造运动造成的天然气自东向西大规模充注对油藏进行气洗改造两大过程的控制。