非静水应力作用固体的化学位及其构造地球化学意义

非静水应力作用的含水岩石中的力学 -化学相互作用是构造地球化学研究的主要对象之一 ,非静水应力作用固体物质的化学位则是了解这种作用的关键。本文在总结前人有关成果的基础上 ,从理论上了提出了非静水应力作用固体岩石中固 -液界面上的固体物质的化学位的一般形式。在此基础上 ,根据 Onsager扩散方程和局部平衡假设 ,推导了固体物质在颗粒间流体中溶解浓度随固体岩石中应力场和应变能的时空变化关系的动力学方程。以此论证了在温度较低时 ,固体物质在颗粒间流体中的溶解的浓度的时间变化是受固体岩石中应力梯度和应变能梯度控制的     

应力作用下岩石的化学动力学溶解机制研究

通过结合化学热力学及动力学、过渡态理论和岩石力学等方面的知识,建立了应力作用下岩石的溶解动力学模型,分析了应力作用对岩石固相物质活度及矿物溶解动力学速率的影响,探讨了应力作用下水岩相互作用机制。研究结果表明：岩石所承受应力与周围流体压力之间存在的应力差所产生的化学势差是应力作用下溶解反应的驱动力;应力的施加显著提高了岩石中固相物质的活度,由此加快了矿物溶解反应的动力学速率;应力作用下的岩石细观溶解机制可根据固液界面应力分配及优先溶解部位上的差别分别用水膜扩散模型或岛渠模型进行描述;应力作用下水岩相互作用存在着应力、化学与渗流的3场耦合问题：应力推动化学反应的发生,化学作用使得岩石表面的细观形貌发生改变,局部的应力分布及大小也随着形貌的变化而改变,进而影响化学反应发生的位置及进程,同时也改变渗流通道的演化规律     

流体晶、流体晶矿物组合、流体岩及其研究意义

流体是地球各圈层之间相互作用的纽带,在成岩、成矿过程中起着十分重要的作用。目前,流体的研究主要集中在流体对先存矿物岩石进行的交代作用方面,而对流体直接结晶形成的矿物领域研究较少。文中根据作者近几年的研究成果对从流体直接结晶而成的矿物——流体晶以及流体晶矿物组合、流体岩等的定义、特征进行了归纳总结。最新的研究结果显示：岩浆中可以含有大量的流体,这些流体来源既可以是岩浆演化富集、岩浆与围岩相互作用产生,亦可以是外部来源。因此,流体晶矿物、流体岩在自然界应该是普遍存在的。流体晶矿物的提出将深化人们对地质过程的理解,发展岩石学及矿床学的研究新领域,有利于矿床勘探和成矿预测。     

高温高压岩石粒间熔体（和流体）形态学及其研究进展

高温高压岩石粒间熔体（和流体）形态学是现代岩石学的前沿领域之一。它主要研究高温高压下低程度部分熔融（或含少量流体）岩石中,矿物颗粒之间熔体（或流体）形态特征、连通性,以及与周围矿物相互关系的科学。研究中较多地借鉴了材料科学的研究方法,与界面物理化学密切相关。高温高压下地幔岩石粒间熔体（和流体）形态学的研究为探讨地幔部分熔融作用、软流圈和地幔交代作用的成因提供了重要的实验依据,已成为地球深部研究的重要手段之一。目前该学科还没有为我国广大地学工作者所熟悉。为此,对高温高压岩石粒间熔体（和流体）形态学的基础理论、实验方法,以及某些实验研究结果进行简要介绍,从而为读者对该学科的了解提供一些便利。     

砂岩中绿泥石膜形貌和组成的成岩过程响应:以鄂尔多斯盆地陇东地区长8砂岩为例

通过铸体薄片、带有能谱仪的场发射扫描电镜技术观察、测试了鄂尔多斯盆地延长组砂岩中绿泥石膜的形貌特征和化学组成,研究了其成因和成岩过程响应及对砂岩物性的影响。研究结果表明,绿泥石膜具有里、外两层膜结构,外层膜的形貌和组成是对粒间孔隙及其流体的物质响应,而里层膜是对颗粒溶蚀小孔腔及其流体的成岩过程响应。外层膜生长在粒间孔隙中,绿泥石晶体大,晶形好,垂直颗粒表面聚集成膜;里层膜发育在碎屑颗粒溶蚀小孔腔中,空间狭窄,致使绿泥石晶体小,晶形差,集合体杂乱堆积。粒间孔隙连通性好,流体组成相近,形成的外层膜化学组成相似;在外层膜对流体的双向阻滞作用下,颗粒溶蚀物质难以移出,而粒间孔中富铁、镁质流体也难以进入,引起溶蚀小孔腔中的流体富颗粒特征组分而贫铁、镁质,形成独具特色的里层膜;外层膜阻碍长石溶解和里层膜消耗长石溶蚀产生的部分硅质流体,造成粒间孔隙中流体的硅质浓度不足以形成大量石英胶结物,从而有利于粒间孔隙的保存。     

试论地球内部流体与地质作用——现代地质科学研究思考

把以地球固体部分作为主要研究对象所建立起来的地质科学称为传统地质科学,它只在该学科研究的起点——沉积地质学和学科研究的最终目的——成矿地质学两个领域不自觉地将地球内部流体放到了重要地位,而在其间的绝大多数研究则忽略了对地球内部流体的讨论,在其原有的知识体系范围内已找不到关于地球内部物质和能量转移、转换等方面所存在的大量问题的解决途径和完整答案。现代地质科学的发展已经开始将地球内部流体作为主要研究对象,并将其贯穿到了所有地质学研究的领域当中。其基本出发点应是：地球内部流体广泛存在,并永不停息地运动着,它与固体地球部分同样重要,是现代地质科学研究的主要对象。它不仅在各种地质作用中起着极其重要的作用, 而且, 它基本上可以认为是一切地质作用的最初根源, 也就是说, 流体作用贯穿于一切地质作用( 包括构造活动、岩浆作用、变质作用、沉积作用、成矿作用、地质自然灾害等) 过程的始终。地球内部一切地质作用又通过地球内部流体有机地统一在一起。可将地球内部流体按其与特定地质作用的关系划分为具包含循环性质的初始流体、过程流体和终结流体三类。针对目前的研究大量地集中在过程流体和终结流体方面的现状, 在体现现代地质科学和传统地质科学本质区别的地质作用初始流体方面进行了系统整理和论述, 并提出了可能成为现代地质科学基础性学科的(地球内部) 流体统一地质学。     

地壳中流体对变质作用的影响

地壳中流体在变质作用过程中具有重要的地位。流体不仅是一种质量运输的介质,更是反应的催化剂或反应物。在一定程度上,变质反应中矿物组合的更替难易度和反应进程主要取决于流体的参与,特别是退变质过程中,流体通过溶解-迁移-沉淀机制使得变质矿物共生组合发生改造。流体与岩石相互作用的研究也进一步的表明反应本身促进了裂隙的发生,即反应促进了岩石渗透率,增加了流体与岩石的接触面积,使得流体与岩石反应界面的反应更加快速与完全。同时,对岩石的力学性质也有重要的影响,诸如岩石的流变学性质及其应变性质,对地壳变形、断裂、岩浆作用、变质作用及成矿作用等有重要的意义。     

两刚性圆球间双黏度流体挤压流动压力分析

颗粒物质是大量固体颗粒相互作用而组成的复杂体系。颗粒间孔隙水具有复杂连通结构和复杂的流动规律,直接影响颗粒体系的变形和强度,目前颗粒间隙液体的挤压流动和剪切运动分析是流体力学的难点。基于Reynolds润滑理论,导出了存在填隙双黏度流体时,两刚性圆球间流体的挤压流动速度场和压力方程。根据应力的变化情况,将流体分为屈服区和未屈服区,讨论了两区厚度与流体及颗粒参数的关系,分析了流体压力分布随计算参数的变化规律,得到了法向挤压黏性力的积分表达式,并给出了黏性力随不同参数的变化规律。     

固液两相流体中的空泡振荡计算

本文导出了固液两相流体中球空泡的振荡方程,并用数值方法讨论了固体颗粒对它泡运动及泡壁压强的影响,得到了固相浓度、颗粒尺寸等因素与空泡运动之间的定性关系。在分析过程中,考虑了液体与颗粒之间力的双向耦合作用。     

颗粒间的毛细作用以及吸应力特征曲线分析

颗粒之间的毛细作用是分析湿颗粒体系力学特性的一个重要方面。考虑两球形颗粒与粒间弯液面的相互作用,采用打靶法求解得到了粒间气-液-固交界面的几何形状与基质吸力关系的精确解答,并与环形近似方法和数据拟合方法得到的粒间作用力进行了比较,分析了两种简化方法的精确度。在此基础上,分析了不同粒间间距、液-固接触角以及基质吸力时,两球形颗粒间由毛细作用引起的吸应力特征曲线。分析结果表明,当液体体积较小时,拟合方法得到的结果更好,而当液体体积较大时,采用环形近似得到的结果要比拟合方法更接近精确解,为非饱和土中吸力的认识以及非饱和土力学微观分析提供了一定的理论指导。     

The role of the fluid phase during regional metamorphism and deformation

Evidence from rock microstructures, mass transfer and isotopic exchange indicates that substantial quantities of aqueous fluids are involved in low- and medium-grade regional metamorphism. Similar conclusions are drawn from many retrograde environments, whereas high-grade metamorphic fluids may be melt dominated. The mobile fluids play essential roles in metamorphic reactions, mass transport and deformation processes. These processes are linked by the mechanical consequences of metamorphic fluid pressures (P_f) generally being greater than or equal to the minimum principal compressive stress. Under such conditions metamorphic porosity comprises grain boundary tubules and bubbles together with continuously generated (and healed) microfractures. Deformation results in significant interconnected porosity and hence enhanced permeability. Lithologically and structurally controlled permeability variations may cause effective fluid channelling.
Simple Rayleigh-Darcy modelling of a uniformly permeable, crustal slab shows that convective instability of metamorphic fluid is expected at the permeabilities suggested for the high P_f metamorphic conditions. Complex, large-scale convective cells operating in overpressured, but capped systems may provide a satisfactory explanation for the large fluid/rock ratios and extensive mass transport demonstrated for many low- and medium-grade metamorphic environments. Such large-scale fluid circulation may have important consequences for heat transfer in and the thermal evolution of metamorphic belts.     

油气幕式成藏及其驱动机制和识别标志

连续稳态流动和周期性(幕式)瞬态流动是沉积盆地流体的 2种流动方式。幕式流体流动是压力和应力的作用引起地层周期性破裂或断裂、先存裂隙周期性开启的结果。幕式成藏是沉积盆地中油气与地层水组成的混相、不连续流体的多期次充注/聚集过程,超压顶界面附近、底辟和深断裂附近是幕式成藏的有利场所。与油气稳态连续聚集过程相比,幕式成藏更快,大 中型油气田可在较短的时间内形成,根据传统模式难以成藏的年轻圈闭可成为有效的勘探目标。幕式流体流动的主要特征是流体成份和流动过程的不连续性、流体流动过程中温度、压力的快速变化及流体流动的多期性和周期性。流体的时空非均质性、流体流动的瞬态温度响应和运移相态分异及其揭示的多期流体相互作用是幕式成藏的有效识别标志。     

The nature of grain boundaries in slates implications for mass transport processes during low temperature metamorphism

The structure of grain boundaries in some very low-grade slates has been studied with transmission electron microscopy. All phyllosilicate boundaries have structural widths of less than 1 nm. A range of structural types have been observed from apparently coherent basal layer chlorite-muscovite boundaries, semi-coherent chlorite-chlorite boundaries and incoherent boundaries which are commonly defined by a thin layer, 7–10 nm thick, of crystalline second phase. Remnants of isolated fluid inclusions are only found at quartz-quartz boundaries. The cleavage microstructures suggest that a large amount of volume loss occurred during cleavage development at low temperatures. This is most likely to have been achieved by diffusion and/or advection through a fluid-filled network present along grain boundaries or grain edges. The phyllosilicate grain boundaries in their present state could not have acted as the pathways for extensive fluid-assisted mass transport. This suggests that the grain boundary structure during cleavage formation was different from the present state. An interconnected fluid network may be maintained along grain boundaries during deformation by hydrofracturing or by grain boundary migration during dehydration reactions, but as deformation and reactions cease the grain boundaries develop an equilibrium structure with very narrow structural widths and restricted fluid distribution.     

The effects of stress on reactions in the Earth: Sometimes rather mean,usually normal,always important

Stress affects chemical processes on all scales in the Earth but the magnitude of its effect is debated. Here, I give a new synthesis of the theory that describes the effects of stress on chemistry, elaborating upon work in Materials Science which is built from fundamental thermodynamic laws, and show its significance in Earth Science. There are separate but compatible relationships describing what happens (1) at interfaces and (2) within grains. (1) The main chemical effects of stress in the Earth are due to variations in normal stress along grain interfaces and between interfaces with different orientations. For reactions involving diffusion these variations give effects on mineral stability broadly equivalent to pressure changes of (molar volume)/(molar volume change during reaction) × (stress variation). The volume ratio is generally large and so the effects of normal stress variations are always important since all stressed rocks have interfaces supporting different normal stresses. There is no global chemical equilibrium in a stressed system, so reaction kinetics contribute to ongoing evolution until stresses relax: this evolution can include deformation by diffusion creep and pressure solution, possibly with new mineral growth. These effects are relevant for predicting the conditions for reactions involving fluids, such as serpentinite formation and breakdown (relevant for the Earth's volatile cycles) and for other reactions such as ringwoodite breakdown (relevant for understanding the 660 km mantle discontinuity). (2) Within stressed solid solution grains it is not possible to define chemical potentials of all chemical components since one has to be specified as “immobile.” The chemical potential of a “mobile” component such as an exchange vector can be defined. It depends on the “partial molar strain,” a second rank tensor defining the variation in unit cell geometry with composition. In cubic crystals the partial molar strain is isotropic and the chemical potential of a mobile component depends on mean stress. In other crystal systems the partial molar strain is anisotropic and the chemical potential depends on a “weighted” mean stress; orientation as well as magnitude of stress has an influence. I propose “chemical palaeopiezometry”—the possibility of measuring past stress levels via chemistry. Examples show that stress variations in hundreds of MPa to GPa are required to produce 2% variations in composition but high stresses and/or precise chemical analyses will allow this proposal to be tested. High stresses around inclusions and dislocations could be targeted. So, the weighted mean stress inside grains has an effect which is relatively minor although potentially valuable in explaining chemical variations; the normal stress at interfaces plays the main role in chemical processes and its effects are of significant magnitude.     

Chemo‐mechanics of cemented granular solids subjected to precipitation and dissolution of mineral species

This paper studies the chemo‐mechanics of cemented granular solids in the context of continuum thermodynamics for fluid‐saturated porous media. For this purpose, an existing constitutive model formulated in the frame of the Breakage Mechanics theory is augmented to cope with reactive processes. Chemical state variables accounting for the reactions between the solid constituents and the solutes in the pore fluid are introduced to enrich the interactions among the microstructural units simulated by the model (i.e., grains and cement bonds). Two different reactive processes are studied (i.e., grain dissolution and cement precipitation), using the chemical variables to describe the progression of the reactions and track changes in the size of grains and bonds. Finally, a homogenization strategy is used to derive the energy potentials of the solid mixture, adopting probability density functions that depend on both mechanical and chemical indices. It is shown that the connection between the statistics of the micro‐scale attributes and the continuum properties of the solid enables the mathematical capture of numerous mechanical effects of lithification and chemical deterioration, such as changes in stiffness, expansion/contraction of the elastic domain, and development of inelastic strains during reaction. In particular, the model offers an interpretation of the plastic strains generated by aggressive environments, which are here interpreted as an outcome of chemically driven debonding and comminution. As a result, the model explains widely observed macroscopic signatures of geomaterial degradation by reconciling the energetics of the deformation/reaction processes with the evolving geometry of the microstructural attributes. Copyright © 2015 John Wiley & Sons, Ltd.     

论油气成藏流体动力系统

提出了油气成藏流体动力系统的概念和重力驱动型、压实驱动型、流体封存及滞流型油气成藏流体动力学系统类型的划分方案。流体动力系统类型的确定从盆地演化史分析和流体动力特征分析两方面来进行。油气成藏主要驱动力的相对重要性在重力驱动型、压实驱动型、流体封存型系统中不同,浮力在３类系统中都重要,水动力只在前两类中重要,而热力仅在第三类中发挥重要作用,地应力在第一和第三类系统中重要。油气成藏流体动力系统研究对油     

岩石和岩体的本构关系

引言岩石和岩体的本构关系(包括适用于可压缩流体的状态方程)是岩石介质的应力(或压力)、应变(或比容)、比内能(或温度)、及加载路径、应变率等之间的普遍关系式.它是研究应力波在岩石介质中的传播规律及其与地下结构相互作用的基础;在估价地下结构对各种爆炸作用的抵抗能力以设计经得起这些作用的防护结构时,在预报周围环境地运动及确定结构--介质相互作用时,都需要岩石和岩体介质的动力响应的精确描述;     

CONSTITUTIVE RELATIONS OF ROCK AND ROCK MASS

The constitutive relations of rock and rock mass are essential to the study of propagation of stress wave in rock medium and its interaction with structure .in this paper ,the development of the research on constitutive relations of rock and rock mass is briefly reviewed ;the equations of state of rock in fluid state at high pressures and the con equations of rock in solid state are mainly described .The cop model as the constitutive equation of rock and its generaligations especially discussed .     

Thermo-hydro-mechanical modeling of fracturing porous media with two-phase fluid flow using X-FEM technique

In this paper, a fully coupled thermo-hydro-mechanical model is presented for two-phase fluid flow and heat transfer in fractured/fracturing porous media using the extended finite element method. In the fractured porous medium, the traction, heat, and mass transfer between the fracture space and the surrounding media are coupled. The wetting and nonwetting fluid phases are water and gas, which are assumed to be immiscible, and no phase-change is considered. The system of coupled equations consists of the linear momentum balance of solid phase, wetting and nonwetting fluid continuities, and thermal energy conservation. The main variables used to solve the system of equations are solid phase displacement, wetting fluid pressure, capillary pressure, and temperature. The fracture is assumed to impose the strong discontinuity in the displacement field and weak discontinuities in the fluid pressure, capillary pressure, and temperature fields. The mode I fracture propagation is employed using a cohesive fracture model. Finally, several numerical examples are solved to illustrate the capability of the proposed computational algorithm. It is shown that the effect of thermal expansion on the effective stress can influence the rate of fracture propagation and the injection pressure in hydraulic fracturing process. Moreover, the effect of thermal loading is investigated properly on fracture opening and fluids flow in unsaturated porous media, and the convective heat transfer within the fracture is captured successfully. It is shown how the proposed computational model is capable of modeling the fully coupled thermal fracture propagation in unsaturated porous media.