磷灰石裂变径迹与结晶C轴的夹角对模拟热历史的影响

磷灰石裂变径迹退火行为是磷灰石裂变径迹技术模拟热历史的基础,退火程度的不同会导致径迹的长度不同,其中退火的各向异性（与结晶C轴夹角不同退火行为不同）是导致长度差异的重要因素。首先利用C轴投影模型将任意夹角的径迹转化成与C轴平行的径迹,以此消除分布方位的影响,进而探讨实际测量长度相同而分布方位不同的径迹模拟的热历史之间的差异。研究结果表明,磷灰石裂变径迹与结晶 C轴夹角不同揭示的最高古地温之间最大差异为15℃,用来研究剥蚀量和年轻造山带冷却抬升速率引起的最大差异可分别达到430 m及1.5℃/Ma,揭示构造抬升事件的初始抬升时间最大可相差2Ma。因此,在实际模拟热历史时应注意该参数的影响,准确测量磷灰石裂变径迹与结晶C轴的夹角将有助于提高模拟热历史的精度。     

融化压缩下水泥改良冻土的微观孔隙特征演变

水泥改良冻土在融化压缩下的微观孔隙演变特征研究,对了解水泥改良冻土的过程具有重要意义。将水泥改良后的冻土进行融化压缩实验,通过冷冻干燥法对试验后的土样进行电镜样品制取并获取其微观特征图像。对试验土样进行比重测试,得到土样真实的三维孔隙比。最后以真实孔隙比作参考,确定图像分割所选取的灰度值并提取其孔隙特征。结合融化压缩试验结果,对水泥改良冻土的孔隙数量、面积、定向角及丰度值随改良土压缩量的变化关系进行了分析。研究结果表明:经过水泥改良后的冻土,大孔隙结构强度增大明显;随着水泥掺量及养护龄期的增加,孔隙比与孔隙面积变大,压缩量变小;随着土体压缩量的增大,孔隙的定向角分布逐渐由均匀状向锯齿状发展;土样压缩过程中,丰度值大于0.5的孔隙发生压缩明显,孔隙逐渐趋于细长状,并且随着压缩量的增大,孔隙丰度值的分布越来越趋于正态分布。孔隙微观结构演变研究为阐释水泥改良冻土宏观力学特性增强的机制提供了科学依据。     

大营地区古层间氧化带识别与空间定位预测

潜在铀储层内部的层间氧化作用与铀成矿作用同时进行而且密不可分,（古）层间氧化带被认为是砂岩型铀矿的重要找矿标志。运用岩芯和钻孔资料以及各分带的岩石矿物学以及地球化学特征等信息识别古层间氧化带,结合铀储层中具有古氧化性质和还原性质的岩石地球化学标志,定量地给予古层间氧化带以空间定位,并据此可以划分出古完全氧化带、过渡带和还原带。在此基础上,探讨了铀储层规模、隔挡层、暗色泥岩及煤层等因素对于古层间氧化带分布的影响。     

靖远煤田宝积山-红会矿区外围赋煤特征及勘查方向研究

靖远煤田宝积山、红会矿区含煤地层为中侏罗统窑街组,煤炭资源较丰富。由于多年开采,资源面临枯竭,解决资源接续问题已成当务之急。通过对区内主要控煤构造白土梁一马饮水复式向斜的展布方向和分布范围、F1h断层特征和煤系地层层序的研究．预测研究区有可采煤层存在．且煤层埋藏深度在1200～2000m。通过分析宝积山、红会两矿区赋煤地层及构造特征,认为研究区与两矿区应属同一山间聚煤坳陷,成煤环境为河湖沼泽相,岩相旋回以河流相开始,泛湖相结束,煤层位于旋回中上部,煤系地层薄,煤层层数少、厚度大,含煤性好,资源储量丰度大。根据已知矿区地质条件,结合以往地质工作程度的差别,提出宜采用不同的勘查方法分区分段开展地质找煤工作。     

Particle Flow Simulation on Collapse Characteristics of Silt Under Mutation of Principal Stress Orientation

The behaviors of granular material and influencing factors under complex dynamic loading are studied by more and more researchers with particle flow method. Only the strain-controlled loading has been generally used in the current study, although this method was not consistent with the practice of engineering in many situations. In this article, stress-controlled dynamic simulation tests were carried out with particle flow method, which were used to study the collapse characteristics of silt under mutation of principal stress orientation. The tests were performed by PFC2D. The simulation results and the laboratory real tests’ results had a high degree of similarity, particularly in the collapse strain and vibration times. It was very useful to forecast the silt's critical failure state. Based on the verification data, the effects of confining pressure and cyclic shear stress ratio on the collapse characteristics of silt were studied further. With the increase of cyclic shear stress ratio, the deviator strain amplitude increased and the required vibration times gradually reduced to achieve the same strain level. Under the same dynamic shear stress ratio and vibration times, the initial dynamic elastic modulus slightly increased with the increase of initial confining pressure, and the variation range of final collapse deviator strain was small. In the analysis of micro-structural evolution, the redistribution of internal stress of sample was revealed during cyclic loading. With the increase of vibration times, the development of distribution gradually stabilized, and then the high shear stress appeared in some connected regions. On that stage, the particle system developed to instability and failure. The PFC simulation results confirmed that the collapse state was the critical stage to trigger the liquefaction of silt.     

An inverse approach to constraining strain and vorticity using rigid clast shape preferred orientation data

We describe a three-part approach for modeling shape preferred orientation (SPO) data of spheroidal clasts. The first part consists of criteria to determine whether a given SPO and clast shape are compatible. The second part is an algorithm for randomly generating spheroid populations that match a prescribed SPO and clast shape. In the third part, numerical optimization software is used to infer deformation from spheroid populations, by finding the deformation that returns a set of post-deformation spheroids to a minimally anisotropic initial configuration. Two numerical experiments explore the strengths and weaknesses of this approach, while giving information about the sensitivity of the model to noise in data. In monoclinic transpression of oblate rigid spheroids, the model is found to constrain the shortening component but not the simple shear component. This modeling approach is applied to previously published SPO data from the western Idaho shear zone, a monoclinic transpressional zone that deformed a feldspar megacrystic gneiss. Results suggest at most 5 km of shortening, as well as pre-deformation SPO fabric. The shortening estimate is corroborated by a second model that assumes no pre-deformation fabric.     

江苏溧水金驹山金多金属矿的控矿因素及找矿方向

通过分析金驹山矿区的地层、构造、岩浆岩、围岩蚀变及矿石构造等地质因素,认为金驹山矿区的断裂构造严格控制着矿区内矿脉和岩脉的规模、产状及产出位置,是矿区的主控矿因素,同时也是矿区的主要找矿标志;粗安斑岩与矿区成矿热液源于同一母岩浆,其分布对矿体分布有一定的指示意义。同时总结矿区成矿规律,认为金驹山矿区神墩山与金驹山之间第四系覆盖区和矿区以北曲山地区为今后寻找金驹山类型矿床的有利地段。     

湖南香花岭地区有色、稀有多金属矿床主要类型及找矿方向

通过研究区域成矿地质背景和香花岭地区有色、稀有多金属矿主要类型及地质特征,总结了本区的成矿条件和成矿规律,认为地层、构造、岩浆岩对矿床的形成起了不同的控制作用,其中岩浆岩是内因,有利的地层岩性及构造空间是外部条件。在此基础上,进一步分析了香花岭地区找矿前景,并指出了炮金山—杉木溪(铷铌钽钨锡铅锌)、黄沙寺—长冲(铅锌锡)、蕉溪—塘官铺—癞子岭(锡铅锌)、新风深部及东部(锡铅锌)、五里山—铁砂坪(锡钨铅锌)、唐家洞(铅锌)等勘查区找矿工作部署重点位置。     

龙岩煤田地质特征及“四下”找煤研究

通过对龙岩煤田深部地质特征及煤系地层之上的各类盖层特征分析,从沉积环境、同沉积构造及后期构造等方面,研究其对童子岩组煤系发育的控制作用,研究其深部煤炭赋存条件及规律,通过勘查案例,提出隐伏区下找煤思路,即推覆体、滑覆体、红层、火山岩下找煤(简称"四下"找煤)。通过分析龙岩煤田隐伏区深部煤炭资源潜力,指出找煤方向,为该区煤田深部勘查和资源预测提供依据。     

基于姿轨参数的高分辨率卫星遥感影像定向模型

文章在基于传统姿轨参数的高分辨率卫星遥感影像定向模型基础上,用轨道半径变化率代替轨道偏心率和近地点幅角,并通过差商内插法求解姿轨参数的偏导系数,使平差所需控制点减少为4个.对SPOT-5HRG影像的试验表明,影像定向后像方检查点中误差小于±2pixels,对地定位精度可满足1∶50 000比例尺测图要求.