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陡倾层状斜向岩层视向溃屈机制力学分析——以陕西山阳滑坡为例 总被引：2，自引：1，他引：1
以陕西山阳滑坡为例,分析了陡倾层状斜向岩层岩质滑坡的视向滑动特征、滑移-溃屈破坏模式与机制。基于梁板理论、层状板裂结构岩体弯曲-溃屈破坏的力学模型在考虑自重、地下水静水压力作用及斜倾层状山体视向滑动侧向摩阻力作用的影响下,采用岩体结构力学分析的方法建立了相应的力学模型;经过力学分析,推导出基于斜坡自重、地下水静水压力与侧向摩阻力作用下的陡倾层状斜向岩层斜坡溃屈段长度条件方程。为验证条件方程的正确性,以山阳滑坡为例进行了验算,最后得出与实际调查较一致的结果,为防御陡倾层状斜向岩层斜坡产生视向溃屈破坏提供依据。 相似文献
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大型反倾库岸岩体变形过程及破坏机制数值模拟 总被引：1，自引：1，他引：0
随着边坡地质结构、地层岩性和诱发因素的不同,反倾岩体的主控变形破坏模式都会发生改变。金沙江龙蟠边坡岩体主要为反倾向千板岩和砂岩互层状结构,坡脚河床深厚覆盖层构成了边坡的软弱支座。本文运用离散单元法模拟了大型反倾库岸岩体在漫长的地质历史时期中的变形演化过程,并基于反倾岩体变形的时效性观点,引入强度折减法分析边坡在不同阶段的剪切屈服区扩展情况及相应的稳定性状态。结论表明龙蟠边坡变形岩体是重力弯曲蠕变为主导的成因机制,并归纳提出了软基效应和互层效应共同作用下的大规模反倾岩体的累进性剪切破坏模式,俗称龙蟠模式。 相似文献
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连通率是岩体内部结构面发育尺寸及贯通程度的重要指标, 决定着岩体的工程力学特性, 对边坡、坝基等工程岩体的整体强度和稳定性评价等发挥着至关重要的作用。以西南地区某水电站拱坝建基典型岩体缓倾结构面为研究对象, 根据现场岩体实测数据, 基于自行开发的裂隙网络模拟程序, 采用蒙特卡洛(Monte-Carlo)随机模拟方法对水电站左、右岸岩体不同剪切方向下缓倾结构面的连通率和岩体强度参数开展研究。研究表明: 该水电站左、右岸岩体在不同剪切方向上的连通率是不同的, 通过不同方向的角度旋转, 总体获得的裂隙连通率较低; 水电站右岸平洞PD02处缓倾角结构面的裂隙连通率约在27.35%左右, 摩擦系数为1.04, 黏聚力为0.89 MPa。研究成果可为水电工程建设提供理论参考和借鉴。 相似文献
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地壳浅表层岩体因受到风化和蚀变作用的影响而导致岩体的孔隙性增加,干密度、抗压强度等物理力学特性降低; 孔隙度作为岩体遭受风化和蚀变作用的重要特征,可以反映出风化和蚀变作用对岩体物理力学特性的影响。因此,可以通过对风化和蚀变花岗斑岩物理力学特性的室内试验,建立孔隙度与其他各项物理力学参数的函数关系,以此分析风化和蚀变对花岗斑岩物理力学特性的影响。研究表明:风化和蚀变花岗斑岩的干密度和抗压强度均随孔隙度的增加而减小,且呈乘幂函数关系,相关系数皆大于0.83; 吸水率与孔隙度则呈二项式函数关系,且随着孔隙度的增加而增加,其相关系数大于0.90; 风化和蚀变都削弱了花岗斑岩的物理力学特性,且随着风化、蚀变程度的增加,花岗斑岩的物理力学特性也呈相应的函数关系降低; 陡倾结构面受风化和蚀变的影响较缓倾结构面强。 相似文献
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本文就四川白马辉长岩质层状岩体中,斜长石的形变现象和分布加以介绍,并对其形成作初浅分析。一、岩体概况和辉长岩的结构构造层状岩体分布于川滇南北构造带中段西侧。南北走向,向西倾。出露长24公里,宽2～2.5公里,总厚三千多米。岩体分异良好,主要由橄榄辉长岩和钛铁矿、磁铁矿超基性岩(下称含矿超基性岩)组成。根据我队裂谷研究队资料,整个岩体自下而上可分为A、B、C三个大的韵律旋回,五个岩相带。本文只涉及到斜长石形变较明显的A、B旋回中的A、B_1、B_2岩相带,即条带状橄榄辉长岩——含矿橄长岩相带(A),条带状 相似文献
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在1∶5万内蒙古察哈尔右翼前旗、隆盛庄、西官村及永善庄4幅区域矿产地质调查的基础上,对以油篓山为代表的侏罗纪岩体从岩石学、岩石化学、稀土及微量元素等特征方面进行了初步研究。采用富集系数来讨论元素富集成矿问题,侏罗纪岩体富集—强富集的元素有Ag、Pb、Zn、As、Sn、Sb、Hg、W、Bi和Mo,说明侏罗纪岩浆活动为成矿提供了含矿热液。岩石化学及地球化学特征研究表明,测区侏罗纪岩体属钙碱性系列的铝饱和—过饱和类型,显示为碰撞阶段岩浆作用产物; 似斑状花岗岩岩体稀土元素配分曲线向右陡倾,倾角较陡,说明轻、重稀土分离明显; 石英斑岩岩体稀土元素配分曲线右倾,倾角平缓,表明轻、重稀土未有明显分馏。 相似文献
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Chemical differences between minerals from mineralizing and barren intrusions from some North American porphyry copper deposits 总被引：1，自引：0，他引：1
D. A. F. Hendry A. R. Chivas J. V. P. Long S. J. B. Reed 《Contributions to Mineralogy and Petrology》1985,89(4):317-329
Major-element analyses (by electron microprobe) and copper contents (by ion-probe) are reported for primary biotite, amphibole,
magnetite, pyroxene, ilmenite, sphene and secondary biotite from intrusive rocks from mineralizing and barren stocks. The
districts studied include Christmas, Globe-Miami, Sierrita and Tombstone, in Arizona; Bingham and Alta, Utah; Ely, Nevada;
and Brenda, British Columbia.
Amphiboles from barren rocks are relatively iron-rich and display only minor compositional variation. In contrast, amphiboles
from mineralizing rocks span the range from magnesio-hornblende to actinolite, commonly even within one grain.
Barren intrusions (type B) that are temporally distinct from mineralizing intrusions, and barren intrusions outside areas
of known mineralization have higher Cu contents in their constituent minerals than do mineralizing intrusions.
Barren intrusions (type A) that are deep-level temporal equivalents of Cu-bearing porphyritic rocks are depleted in copper.
This suggests that copper is abstracted from not only the apical portions of porphyries but from parts of the deeper parent
intrusions.
The Cu contents of biotites (av. 23 ppm) and magnetites (97 ppm) from barren type B intrusions contrast with those from mineralizing
intrusions, with biotites containing 7 ppm Cu and magnetites 3 ppm Cu. Primary amphiboles from all intrusive rock types have
low copper contents, typically 2 to 5 ppm.
In the continental North American deposits, the amount of copper available by liberation from or non-incorporation into amphibole,
biotite and magnetite during magmatic crystallization or the early hydrothermal stage is low, perhaps too low to be the sole
source of copper mineralization, unless copper is abstracted from large volumes (∼ 100 km3) of rock. These results contrast with a study of the island-arc porphyry copper at Koloula, Guadalcanal, where it was argued
that sufficient copper for mineralization could have been abstracted from relatively small volumes of host rocks that originally
contained as much Cu as the contemporaneous barren rock types. 相似文献
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铜陵凤凰山岩体SHRIMP锆石U-Pb年龄与构造变形及其对岩体侵位动力学背景的制约 总被引：31，自引：0，他引：31
地球动力环境对岩浆来源和侵位机制具有重要的控制作用.铜陵矿集区中生代中酸性侵入岩和大规模成矿作用有密切关系.凤凰山岩体为凤凰山矿田的主要组成部分, 主要岩石类型为花岗闪长岩、石英二长闪长岩.根据精确锆石SHRIMP测年结果, 凤凰山岩体206Pb/238U年龄为(144.2±2.3) Ma, 是晚侏罗世形成的一个典型岩体, 和铜陵矿集区主要成矿岩体的形成时代一致.接触带构造变形特征显示岩体侵位受控于区域左旋剪切应力场作用.内部构造变形特征表明凤凰山岩体在深部主要为左旋螺旋式强力上升, 浅部为气球膨胀式主动侵位.岩体形成时代及构造变形特征表现出晚侏罗世铜陵矿集区和成矿有关的侵入岩系列的形成可能和古太平洋板块的向北斜向俯冲所导致的左旋剪切应力场有关. 相似文献
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安徽凤凰山岩体岩浆侵位过程的磁性研究 总被引：2，自引：0，他引：2
通过对安徽省铜陵地区凤凰山岩体25个采样点302件岩石样品的磁性分析,认为研究区内所得的岩石磁组构能代表岩浆侵位时的流动型磁组构,它受岩浆形成之后的构造活动的影响较小;岩浆侵位过程是准静态过程,岩浆流动性较弱、分异作用和同化混染作用强烈;岩浆侵位过程的早期可能受北北东方向的最大主压应力的控制,后期受西南方向最大主压应力场的控制;凤凰山岩体的西南部(药园山矿床所在地段)是岩体的上盘,北东部(仙人冲矿床所在地)是岩体的下盘,即凤凰山岩体向西南方向倾伏;凤凰山岩体的西南部附近地区(如来龙山等地),可能有与凤凰山岩体侵位同时期形成的小岩株,是找矿的远景区段。 相似文献
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多宝山斑岩铜矿床成因模式 总被引：4，自引：1，他引：4
多宝山斑岩铜矿床位于蒙古—鄂霍茨克(古亚洲)地槽东部。矿区周围出露的地层以中古生界为主,在复背斜核部出露有奥陶系。从多宝山矿区向东南40公里为新开岭隆起,隆起呈北东东走向,上面地层多属下古生界和前古生界,而其东南广大地区地层多属石炭二叠系。多宝山矿区含矿的花岗岩体,经K-Ar法年龄测定,为292百万年,属中石炭世。由此可见,在多宝山矿床形成期间,多宝山矿区应位于正负构造单元接壤处偏隆起一侧。 相似文献
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地球内部物质、能量交换与资源和灾害 总被引：11，自引：1，他引：11
通过对凤凰山岩体接触带的变质与变形特征、显微构造及变形缩短量的计算 ,分析了凤凰山岩体侵位与接触带变形及区域变形的关系。通过接触带变质矿物变形特征的研究 ,揭示了热变质作用与侵位变形的同时性 ;接触带构造变形研究表明 ,岩体周围发育的流变褶皱、韧性剪切带、压溶缝合线等与岩体左旋上升与汽球膨胀侵位有关 ;围岩缩短量的计算结果表明 ,岩体侵位过程造成强烈的围岩缩短是一种强力侵位机制。研究表明 ,凤凰山岩体侵位是在区域NNE向水平左旋剪切应力场作用下完成的。岩体接触带变形是NNE向水平左旋剪切应力与横向推挤的侵位应力联合作用下形成的。 相似文献
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斯克瑞斯斑岩型铜矿位于希腊北部哈尔基迪基半岛,塞尔维亚马其顿成矿带。矿体赋存于侵入到韦尔蒂斯科斯组的古近纪—新近纪碱性岩体中,岩体的分布受深部断裂影响。截至2011年,斯克瑞斯矿床已开采5.2×108t铜,Cu平均品位为0.5%,Au平均品位为0.8×10-6,Pd平均品位为110×10-9,Pt平均品位为17×10-9。铜-金矿化呈脉状、网脉状及浸染状分布于岩体及围岩中。矿石矿物主要为黄铜矿、斑铜矿、黄铁矿等,与矿化有关的围岩蚀变主要有钾长石化、硅化、青磐岩化、绢云母化等。锆石U-Pb年龄、全岩Ar-Ar年龄和矿床地球化学特征均显示,岩浆侵位与成矿作用之间关系密切,其形成时代约为19Ma。该矿床以Pd-Pt含量较高为特征。对斯克瑞斯斑岩型富铂族元素斑岩铜矿特点及成矿规律的系统总结,可以为在中国境内寻找同类矿床提供参考。 相似文献
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安徽铜陵凤凰山铜矿是铜陵矿集区内最典型的矽卡岩型铜矿床之一,也是凤凰山矿田内规模最大的铜矿床。矿区内新屋里岩体属于高钾钙碱性系列,主要岩性为石英二长闪长岩和花岗闪长岩。岩石地球化学特征表明凤凰山中酸性侵入岩岩浆属于壳幔混合型,原始岩浆来源于上地幔碱性玄武岩区并有地壳物质混染,在岩浆不断演化过程中有外来物质的加入,成岩过程以混合作用为主。凤凰山铜矿体分布于岩体与大理岩的内矽卡岩带上,岩体中铜含量较高。铜矿体是岩浆期后热液交代碳酸盐地层形成的。矿体的空间分布受构造变形-岩浆侵入高温高压作用的双重控制。矿化经历了从高温矽卡岩阶段到中低温热液阶段的多期次复合成矿作用。 相似文献
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Avriel Venis L. Cirineo Akira Imai Ryohei Takahashi Redempta P. Baluda Noel C. Oliveros Victor B. Maglambayan Roy Ronald C. Luis Maria Lourdes M. Faustino Jacky Almadin 《Resource Geology》2021,71(1):1-40
The Southwest prospect is located at the southwestern periphery of the Sto. Tomas II porphyry copper–gold deposit in the Baguio District, northwestern Luzon, Philippines. The Southwest prospect hosts a copper‐gold mineralization related to a complex of porphyry intrusions, breccia facies, and overlapping porphyry‐type veinlets emplaced within the basement Pugo metavolcanics rocks and conglomerates of the Zigzag Formation. The occurrences of porphyry‐type veinlets and potassic alteration hosted in the complex are thought to be indications of the presence of blind porphyry deposits within the Sto. Tomas II vicinity. The complex is composed of at least four broadly mineralogically similar dioritic intrusive rocks that vary in texture and alteration type and intensity. These intrusions were accompanied with at least five breccia facies that were formed by the explosive brecciation, induced by the magmatic–hydrothermal processes and phreatomagmatic activities during the emplacement of the various intrusions. Hydrothermal alteration assemblages consisting of potassic, chlorite–magnetite, propylitic and sericite–chlorite alteration, and contemporaneous veinlet types were developed on the host rocks. Elevated copper and gold grades correspond to (a) chalcopyrite–bornite assemblage in the potassic alteration in the syn‐mineralization early‐mineralization diorite (EMD) and contemporaneous veinlets and (b) chalcopyrite‐rich mineralization associated with the chalcopyrite–magnetite–chlorite–actinolite±sericite veinlets contemporaneous with the chlorite–magnetite alteration. Erratic remarkable concentrations of gold were also present in the late‐mineralization Late Diorite (LD). High XMg of calcic amphiboles (>0.60) in the intrusive rocks indicate that the magmas have been oxidizing since the early stages of crystallization, while a gap in the composition of Al between the rim and the cores of the calcic amphiboles in the EMD and LD indicate decompression at some point during the crystallization of these intrusive rocks. Fluid inclusion microthermometry suggests the trapping of immiscible fluids that formed the potassic alteration, associated ore mineralization, and sheeted quartz veinlets. The corresponding formation conditions of the shallower and deeper quartz veinlets were estimated at pressures of 50 and 30 MPa and temperatures of 554 and 436°C at depths of 1.9 and 1.1 km. Temperature data from the chlorite indicate that the chalcopyrite‐rich mineralization associated with the chlorite–magnetite alteration was formed at a much lower temperature (ca. 290°C) than the potassic alteration. Evidence from the vein offsetting matrix suggests multiple intrusions within the EMD, despite the K‐Ar ages of the potassic alteration in EMD and hornblende in the LD of about the same age at 3.5 ± 0.3 Ma. The K‐Ar age of the potassic alteration was likely to be thermally reset as a result of the overprinting hydrothermal alteration. The constrained K‐Ar ages also indicate earlier formed intrusive rocks in the Southwest prospect, possibly coeval to the earliest “dark diorite” intrusion in the Sto. Tomas II deposit. In addition, the range of δ34S of sulfide minerals from +1.8‰ to +5.1‰ in the Southwest prospect closely overlaps with the rest of the porphyry copper and epithermal deposits in the Sto. Tomas II deposit and its vicinity. This indicates that the sulfides may have formed from a homogeneous source of the porphyry copper deposits and epithermal deposits in the Sto. Tomas II orebody and its vicinity. The evidence presented in this work proves that the porphyry copper‐type veinlets and the adjacent potassic alteration in the Southwest prospect are formed earlier and at a shallower level in contrast with the other porphyry deposits in the Baguio District. 相似文献
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本文从地质、地球化学以及矿化蚀变特征等方面对凤凰山矿田内两类不同成矿岩体的特征进行了对比,指出凤凰山复式岩体由早期的花岗闪长岩和晚期的石英二长闪长斑岩所组成,与花岗闪长岩有关的成矿作用主要为矽卡岩型成矿作用,与石英二长闪长斑岩有关的成矿作用主要为斑岩型成矿作用.并对新发现的斑岩型矿化的大地构造背景、围岩、蚀变特征、控矿构造以及矿石类型进行了阐述.最后,在综合分析成矿物质来源、物理化学条件、成矿流体和成矿作用的基础上,对凤凰山铜矿床的成因进行了探讨,认为矿床的形成主要与中酸性岩浆活动有关,经历了多种成矿作用,形成了多种矿化型式,矿床成因属以岩浆热液为主的复合型热液矿床. 相似文献