浅析莱芜接触交代-热液铁矿的双交代渗滤作用     

杨昌彬  宗信德  卢铁元  汪云  方传昌 《地质找矿论丛》2006,21(Z1):85-89

莱芜接触交代-热液铁矿赋存于奥陶系马家沟组碳酸盐岩与燕山晚期闪长岩的接触带及其附近.通过对各矿床有益有害组分分析,以及对成矿母岩、围岩岩石化学特征、双交代渗滤作用和围岩蚀变类型等研究,总结出"三位一体"成矿模式,进而探讨了矿体的空间分布规律及其找矿意义.  相似文献   

Kinetics of bubble collision and attachment to hydrophobic solids: I. Effect of surface roughness     

M. Krasowska  K. Malysa 《International Journal of Mineral Processing》2007

Influence of surface roughness of the Teflon plates on kinetics of the bubble attachment was studied. Phenomena occurring during collisions of the air bubble, rising in clean water, with Teflon plates, differing only in their surface roughness, were recorded and analysed using a high-speed camera. Variations of the local velocity of the bubble during the collisions and the time of the bubble attachment were determined. It was found that the Teflon surface roughness was the parameter of a crucial importance for the attachment time of the colliding bubble. Depending on degree of the surface roughness the time of the attachment varied by over order of magnitude (from 3 to over 80 ms). In the case the Teflon surfaces having roughness below 1 μm there were recorded four to five “approach–bounce” cycles prior to the bubble attachment. Moreover, after the first collision the rapid pulsations of the bubble shape (within fraction of millisecond) were recorded. For surfaces of roughness ca. 50 μm and larger the attachment always occurred during the first collision—there was no bouncing observed and the time of the attachment was below 3 ms. It was documented that presence of a micro-bubble at the surface facilitated attachment of the colliding bubble.  相似文献   

Accessory phase petrogenesis in relation to major phase assemblages in pelites from the Nelson contact aureole, southern British Columbia     

H. S. TOMKINS  D. R. M. PATTISON 《Journal of Metamorphic Geology》2007,25(4):401-421

Monazite petrogenesis in the Nelson contact aureole is the result of allanite breakdown close to, but downgrade and therefore independent of, major phase isograds involving cordierite, andalusite and staurolite. The development of garnet downgrade of the staurolite and andalusite isograds does not appear to affect the onset of the allanite-to-monazite reaction but does affect the textural development of monazite. In lower pressure, garnet-absent rocks, allanite breakdown results in localized monazite growth as pseudomorphous clusters. In higher pressure, garnet-bearing rocks, allanite breakdown produces randomly distributed, lone grains of monazite with no textural relationship to the original reaction site. Fluids liberated from hydrous phases (chlorite, muscovite) during garnet formation may have acted as a flux to distribute light rare earth elements more widely within the rock upon allanite breakdown, preventing the localized formation of monazite pseudomorphs. Despite these textural differences, both types of monazite have very similar chemistry and an indistinguishable age by electron microprobe chemical dating (157 ± 6.4 Ma). This age range is within error of isotopic ages determined by others for the Nelson Batholith. Garnet from the garnet, staurolite and andalusite zones shows euhedral Y zoning typified by a high-Y core, low-Y collar and moderate-Y annulus, the latter ascribed to allanite breakdown during garnet growth in the garnet zone. The cause of the transition from high-Y core to low-Y collar, traditionally interpreted to be due to xenotime consumption, is unclear because of the ubiquitous presence of xenotime. Accessory phase geothermometry involving monazite, xenotime and garnet returns inconsistent results, suggesting calibration problems or a lack of equilibration between phases.  相似文献   

多覆盖地区花岗岩接触带及其控矿特征的遥感研究   总被引：3，自引：0，他引：3  

王志刚  郭子祺  马超飞 《国土资源遥感》1998,9(2):41-45,32

本文主要介绍应用TM图像对西秦岭地区的中川岩体进行研究的成果,即研究在多植被、多黄土覆盖的复杂条件下,如何依据接触带蚀变岩的遥感图像像元亮度值及实验室测得的光谱曲线特征,区分不同的岩体接触带类型,并探讨它们对金矿的控制作用。  相似文献   

夹皮沟金矿燕山期花岗岩体外接触带构造控矿及成矿预测   总被引：4，自引：0，他引：4  

孙忠实  杨永强  冯亚民 《地质找矿论丛》1998,13(3):15-23

夹皮沟金矿床主要成矿时代和控矿构造类型－直悬而未决,矿区及外围找矿始终处于徘徊阶段,经控矿构造深部组成和岩浆岩,脉岩,金矿石相互间关系的研究,金主要成矿归代为燕山期,控矿构造类别属外接触带断裂型,找矿靶区应重点选在燕山期隐伏花岗岩体北东侧变质围岩中。  相似文献   

Thermal calculation for high-pressure contact metamorphism: application to eclogite formation in the Sebadani area, the Sambagawa belt, SW Japan     

Mutsuki Aoya   《Earth and Planetary Science Letters》1998,160(3-4):681-693

Eclogite, a high-pressure–temperature metamorphic rock characterized by garnet + omphacite, is usually considered to be a product of regional metamorphism under a low geothermal gradient. However, in the Sebadani area of the Sambagawa metamorphic belt most petrologists agree that the eclogite formed by localized contact metamorphism due to intrusion of a body in the solid-state (the Sebadani mass). This process is termed ‘high-pressure contact metamorphism'. However, geological considerations suggest that the effect of such a process would be limited, firstly because the speed of emplacement for solid-state material will generally be much lower than that for magma and secondly because in the solid-state there is no heat of fusion in the body available for thermal effects. Thermal modelling of a solid-state intrusion, based on the heat conduction equation, allows the relationship between size of intrusion, velocity of emplacement and thermal effects to be calculated. Two cases have been considered: (1) a hot model, where none of the heat conducted into the surroundings is lost during the rise of the body; and (2) a cold model where all the heat conducted into the surroundings is lost. These models bracket possible thermal histories of the body. Calculations suggest that in the Sebadani region, production of the observed metamorphic features requires unrealistically high velocity and a much larger intruded body than is observed. These conclusions suggest that it is unlikely that eclogite in the Sebadani area was formed by high-pressure contact metamorphism, but rather that it represents the highest-grade part of the regional Sambagawa metamorphism.  相似文献   

高速铁路对东北城市网络结构的空间影响   总被引：2，自引：0，他引：2  

刘书舟  韩增林  郭建科 《地理科学》2020,40(2):270-279

借鉴复杂网络理论,以铁路列车时刻表为基础数据,探讨高速铁路的开通对东北地区铁路网络结构和城市网络结构的空间影响。结果表明：① 高铁强化了东北地区铁路网络的小世界、无标度等网络特征,各网络节点在可达性和辐射能力方面受到4种不同形式的影响;② 高铁强化了沈阳和哈尔滨的主-副双核心铁路网络结构,使得拓扑网络的离散程度大幅降低,长春、大连等城市的网络联系中心性显著提升;③ 铁路交通重心向西北方向偏移,区域间不平衡性增强,吉林省成为东北铁路客运联系强度最高的地区;④ 大连市拥有特殊的门户城市特征,即对外联通能力强,但未形成足够吸引力。  相似文献   

DEM analyses of crack propagation in flawed rock mass under uniaxial compressionEI北大核心CSCD     

Jiang Ming-jing  Zhang Ning  Shen Zhi-fu  Chen He 《岩土力学》2015,(11):3293-+

A contact model for rock is established and imbedded into a DEM software by summarizing the bond granule tests. DEM simulation of uniaxial compression test on the pre-cracked Lac du Bonnet granite is performed, and then stress distributions are further analyzed and compared with the theoretical results. Different fracture criteria are employed to predict the crack initiation angles that are compared with theoretical ones. The results show that the failure modes obtained from DEM simulation are similar to experimental results, and stress distributions in DEM simulation are qualitatively similar to theoretical values. When the angle of pre-crack is small, the lateral stresses are compressive and tensile. The compressive strains concentrate at two edges, resulting in the tensile strains in the up-and downward cracks. When the angle of the pre-crack is large enough, the stress concentration is unobvious, leading to a discrepancy between the DEM and theoretical results. The crack extension angle resulting from uniaxial compression measured from DEM tests are in good agreement with those acquired from experimental tests. These angles are consistent with theoretical predictions by the maximum circumferential stress criterion and the maximum energy release rate criterion.  相似文献   

基于半数值方法的限弯器剪弯刚度分析     

丁乐声  陈金龙  陈潇  郭豪  张聪 《海洋工程》2022,40(6):152-159

柔性管缆限弯器存在接触非线性导致剪弯刚度分析困难。为此先基于悬臂梁方程建立剪弯刚度理论模型;然后构建考虑接触边界的锁合结构数值模型,得到其扭转刚度曲线;最后结合理论分析和数值计算求得考虑接触非线性的限弯器剪弯刚度曲线,并同传统的整体数值方法相比较,验证该半数值分析方法的有效性。对比发现基于半数值方法的限弯器剪弯计算效率远高于传统数值方法,其结果误差也满足工程需求;并且限弯器锁合结构处受接触边界影响有明显的非线性;限弯器子梁这一短梁结构基于Timoshenko梁理论计算的结果精度更高也更保守。相较于传统数值方法,该半数值方法用方程直接表达部分参数与剪弯刚度关系,并可以高效地分析限弯器剪弯刚度,使设计工作更加高效。  相似文献   

Empirical Analysis of City Contact in Zhujiang （Pearl） River Delta,China     

TONG De  LIU Tao  LI Guicai  YU Lei 《中国地理科学(英文版)》2014,24(3):384-392

In traditional urban geography, city contact research is a classic study element in city research. In general, researchers use the traditional gravity model to characterize the contacts that exist between two cities. The traditional gravity model assumes ideal condi- tions, but these preconditions and their results often do not exist in realistic conditions. Thus, we used a modified gravity model to char- acterize the city contacts within a specific region. This model considers factors such as intercity complementarities, government inter- vention, and the diversity of the transportation infrastructure which is characterized as the transportation distance instead of the tradi- tional Euclidean distance. We applied this model to an empirical study of city contact in the Zhujiang （Pearl） River Delta （PRD） of China. The regression results indicated that the modified gravity model could measure city contact more accurately and comprehen- sively than the traditional gravity model, i.e., it yielded a higher adjusted R2 value （0.379） than the traditional gravity model result （0.259）. Our study also suggests that, in addition to urban-regional and metropolitan development, the complementarities of the basic functions of cities at the administrative and market levels, as well as the corporeal and immaterial levels, play very significant roles in the characterization of city contact. Given the complexity of city contact, it will be necessary to consider more relevant influential fac- tors in the modified gravity model to characterize the features of city contact in the future.  相似文献