鲜水河断裂带炉霍旦都土林构造初步研究

鲜水河断裂带的断层破碎带在四川省炉霍县旦都一带发育成土(石)林构造。其原岩为中-上三叠统如年各岩群(一套含灰岩滑塌块体的火山-构造混杂岩地层单位)变质砂岩夹板岩,在再脆性变形机制下断裂破碎形成。其内发育一组倾角较缓的劈理构造,可能是重力与地震波联合作用的产物。其内的擦痕、阶步构造显示至少存在早期右行,晚期左行两个活动阶段,并且左行走滑常伴有逆冲分量。     

川东北元坝地区须家河组石英砂岩沉积与储层特征

在川东北元坝及周边地区首次发现纯净的石英砂岩沉积,石英砂岩厚度10~15 m左右。研究表明,石英砂岩主要以夹层形式出现在须一、二段,但沉积环境相当特殊,主要为海泛或湖泛早期沉积的滩坝砂体,不属于须家河组广泛发育的三角洲沉积体系,石英砂体呈近东西向展布,明显受到米仓山-大巴山前陆前渊带的控制。石英砂岩以粉-细砂为主,分选好,磨圆度高,杂基含量低,具有较高的成熟度,与其它地区不同,研究区石英砂岩具有良好的储集性能,其主要原因是由于石英砂岩中石英颗粒内具有高密度原生微裂缝,这些原生裂缝在沉积后成岩过程中可能闭合,但在后期的构造挤压背景下石英砂岩的脆性特性及破碎颗粒容易导致大量裂缝发育,裂缝的发育同时促进原生裂缝充填物和粒间填屑物的溶蚀,形成以裂缝为主的孔隙性储层。在研究区具有裂缝的石英颗粒并不局限在石英砂岩,我们推测具有裂缝的石英与物源有关。     

贝尔凹陷油成藏要素空间匹配关系及对油成藏的控制作用

通过贝尔凹陷油成藏要素--南屯组源岩、裂缝及断层圈闭和源断裂的空间匹配关系研究得到,贝尔凹陷裂缝和断层圈闭与南屯组源岩在空间上有4种接触关系,第一种是布达特群裂缝圈闭位于南屯组源岩侧上方,由T₅-T₁源断裂连接;第二种是南屯组断层圈闭位于南屯组源岩内,由T₂₃-T₁源断裂连接;第三种是南屯组断层圈闭位于南屯组源岩外侧,由T₂₃-T₁断裂沟通的砂体连接;第四种是大磨拐河组二段断层圈闭位于南屯组源岩之上,由T₂₃-T₁断裂连接。贝尔凹陷3个成藏要素空间匹配关系对油成藏与分布的控制作用表现在以下3个方面:①南屯组源岩分布控制着油藏分布;②油藏均沿源断裂分布;③圈闭距南屯组源岩距离越近越有利于油藏形成。     

崇安地区铀矿成因与矿区断裂构造的关系

崇安地区位于武夷-云开-台湾造山系华夏地块桃山-诸广岩浆弧北部东缘部位,其东侧与武夷山基底断隆带毗邻,断裂构造极其发育。断裂构造发育在地壳的不同深度和圈层,对各种矿化起着不同的控制作用。笔者通过对区内控矿构造和铀矿化主要地质特征的分析,论述了断裂构造与铀成矿的关系,认为断裂构造不仅为成矿流体的运移提供了通道,为成矿物质提供了沉淀富集的场所,而且还影响着铀矿床的空间分布、成矿力学环境、成矿物理化学条件等。该区断裂构造具有多期活动的特点,具有压性、压扭性、张性、张扭性等性质。岩浆期后含矿热液沿火山盆地盖层与基底接触的构造破碎带或外带的构造破碎带运移,并在破碎带中充填、交代而形成铀矿体。因此,断裂构造是铀成矿的必要条件,与成矿有着密切关系。     

河南嵩县庙岭金矿地质特征与钾长石~（40）Ar/^（39）Ar定年

河南嵩县庙岭金矿位于华北陆块南缘熊耳山—外方山地区。矿床赋存于中元古界熊耳群火山岩中近南北向断裂带内,矿体呈似层状、透镜状产出,矿石具浸染状、细网脉状构造和微细粒它形粒状晶粒结构、交代结构,围岩热液蚀变有硅化、钾长石化、绢云母化、黄铁矿化等,矿化具有多阶段的特点,属破碎带蚀变岩型金矿。成矿热液蚀变矿物钾长石Ar-Ar法测年的结果：坪年龄为121.6Ma±1.2Ma,等时线年龄为117.0Ma±1.6Ma,表明矿床形成于早白垩世,与熊耳山地区祁雨沟、瑶沟等金矿床形成于同一时期,属与早白垩世构造-岩浆-流体活动有关的产物。     

复式断陷边界控陷断层生长特征及油气地质意义

内容提要：在陆内裂陷盆地中,复式断陷的边界控陷断层具有分段生长的特征,通过古断距回剥技术利用最大断距相减法,对松辽盆地长岭早白垩世复式断陷群东部的5个断陷边界控陷断层形成演化历史进行恢复。得到各边界控陷断层形成均经历“孤立分段”—“软连接”—“硬连接”3个演化阶段,最终形成一条统一的边界控陷断层,即沿边界控陷断层走向多个次级断陷复合最终形成统一的断陷特点。但各个边界控陷断层分段生长演化历史具有差异性。这对复式断陷内油气聚集成藏具有十分重要的地质意义：边界控陷断层的分段生长控制复式断陷的复合时期,进而控制着不同时期有效烃源岩的分布范围;边界控陷断层分段生长的连接部位对火山岩与碎屑岩储层发育均有控制作用;各个次级断陷在复合过程中形成的古隆起往往是油气聚集的有利部位。     

Rock interface strength influences fluid-filled fracture propagation pathways in the crust

Rock interface strengths have often been assumed to be zero in numerical and analogue models of fracture propagation and magma intrusion in the crust. Rock strength tests were performed to explore the role that rock interfaces have on the geometry and propagation dynamics of fluid-filled fractures in the crust. We used a 1 kN test machine to study 5 mm thick cuboidal specimens cut from a sandstone-siltstone rock core, where the strata were known to host magma intrusions and the rock interface between the units was intact. By measuring the load required to grow a crack running along the lithological contact between the layers we calculate its fracture toughness K_c. The siltstone had an average K_c of 0.56 ± 0.03 MPa m^1/2 compared to the sandstone at 0.42 ± 0.02 MPa m^1/2. The rock interface had intermediate average fracture toughness to the parent units at 0.45 ± 0.03 MPa m^1/2. These results have important implications on fracture propagation pathways through rocks, as well as for the geometry and propagation dynamics of magma intrusions in the crust.     

A coupled hydro-mechanical analysis for prediction of hydraulic fracture propagation in saturated porous media using EFG mesh-less method

The details of the Element Free Galerkin (EFG) method are presented with the method being applied to a study on hydraulic fracturing initiation and propagation process in a saturated porous medium using coupled hydro-mechanical numerical modelling. In this EFG method, interpolation (approximation) is based on nodes without using elements and hence an arbitrary discrete fracture path can be modelled.The numerical approach is based upon solving two governing partial differential equations of equilibrium and continuity of pore water simultaneously. Displacement increment and pore water pressure increment are discretized using the same EFG shape functions. An incremental constrained Galerkin weak form is used to create the discrete system of equations and a fully implicit scheme is used for discretization in the time domain. Implementation of essential boundary conditions is based on the penalty method. In order to model discrete fractures, the so-called diffraction method is used.Examples are presented and the results are compared to some closed-form solutions and FEM approximations in order to demonstrate the validity of the developed model and its capabilities. The model is able to take the anisotropy and inhomogeneity of the material into account. The applicability of the model is examined by simulating hydraulic fracture initiation and propagation process from a borehole by injection of fluid. The maximum tensile strength criterion and Mohr–Coulomb shear criterion are used for modelling tensile and shear fracture, respectively. The model successfully simulates the leak-off of fluid from the fracture into the surrounding material. The results indicate the importance of pore fluid pressure in the initiation and propagation pattern of fracture in saturated soils.     

Damage characterization during laboratory strength testing: A 3D-finite-discrete element approach

A combined finite-discrete element approach is used to simulate the complete 3D fracture process during conventional laboratory testing, including Brazilian indirect tension and uniaxial and biaxial compression. A typical granite rock type (based on the Lac du Bonnet granite) was simulated to investigate the fracture pattern and mechanical strength of brittle rock in the laboratory. Damage intensity parameters (D₂₁ and D₃₂) are introduced and utilized to characterize the induced damage in the models. These parameters provide an improved representation of the cumulative associated damage and facilitate a quantitative characterization of crack intensity during testing. The numerical simulations included both 3D and 2D models, and show that there is a good agreement between the strength response derived from simulations both in 3D and 2D and the considered rock material. A good correlation also exists between the fracture pattern in 3D and the equivalent 2D models. The influence of confinement on the biaxial strength and the associated damage in compression is investigated. While axial splitting is the dominant failure mode at low confinement, finite-discrete element simulations show that a shear failure mode tends to dominate as the confinement increases. The dependency of dilation upon the confining pressure is also demonstrated, the dilation angle decreasing with increased confinement.     

广西福海山地区物探测量结果及其解释

简要介绍了高精度磁测、210 Po法和EH-4电导率成像系统的工作原理。通过对已知矿床剖面试验成果分析解释,发现在铀矿体上方地表存在负磁异常和210 Po异常。把福海山地区高精度磁测和210Po法面积测量结果与已知矿床剖面试验成果进行对比分析,圈出了铀矿化区和断裂构造F1、隐伏断裂F0的分布特征,并采用EH-4电磁测深进行验证。说明利用高精度磁测和210 Po法可以有效地推测出测区构造、断裂带的分布范围,为矿区矿化地段深部找矿工作提供有利的勘查区域范围,为下一步的普查工作提供了可靠的地球物理依据。