辽宁省八家子铅锌矿炉沟旋扭构造的控矿作用     

春乃芽  金成洙  冯国清  宋雨春 《矿产与地质》2004,18(5):446-449

在成因上，八家子铅锌矿被认为是岩浆热液充填交代型多金属矿田，断裂构造特别是断裂交汇部位严格控制着若干矿床和矿体的产出，而矿区中部的炉沟岩体与各矿床有着重要的联系，通过对矿区断裂构造的形态特征及相关控矿地质特征的综合分析，认为八家子矿实际上是受一个以炉沟岩体为砥柱的旋扭构造控制的大型矿田。指出以炉沟岩体为中心的主要控矿断裂以左旋式构造形态呈弧形展布，在这些断裂上，无论是矿床分布、元素分带还是矿床成矿温度都表现出分带性特点，而这些特点均符合一般意义上的旋扭构造的特征。这一认识的重要意义在于；控矿断裂和炉沟岩体是一个有机的整体，两者在找矿预测中应处于同等重要的地位。  相似文献   

山西原平狐狸山金矿围岩蚀变特征与金矿化的关系   总被引：1，自引：0，他引：1  

刘恩锋  李远镭 《吉林地质》2002,21(3):54-59

狐狸山金矿是韧性剪切带型金矿床，矿区围岩蚀变发育广泛，类型有碳酸盐化，绢云母化，硅化等，蚀变分带明显，且蚀变强度与金矿化关系密切。围岩蚀变受韧性剪切变形影响，金矿化与围岩蚀变的主要期次同时形成。  相似文献   

Oscillatory zoning in eclogitic garnet and amphibole,Northern Serpentinite Melange,Cuba: a record of tectonic instability during subduction?   总被引：1，自引：0，他引：1  

A. García-Casco  R. L. Torres-Roldán  G. Millán  P. Monié  J. Schneider 《Journal of Metamorphic Geology》2002,20(6):581-598

Exotic blocks of eclogite from distant localities along the Northern Serpentinite Melange of Cuba have comparable P–T histories that include high‐pressure prograde sections (450–600 °C, >15 kbar) associated with subduction of oceanic lithosphere, and retrograde sections within the albite–epidote amphibolite facies (<500 °C, <10 kbar) related to melange uplift. ⁴⁰Ar/³⁹Ar and Rb/Sr cooling ages (118–103 Ma) of one of the blocks indicate pre‐Aptian subduction and Aptian–Albian uplift. Detailed X‐ray imaging and profiling further reveals that minerals in these eclogite blocks (notably garnet and amphibole) display subtle but well defined oscillatory zoning that developed along the prograde trajectory of the rocks, previous to attainment of peak eclogitic conditions. The chemistry (e.g. coupled changes of Mg# and Mn in garnet, and of Si, Ti, Al and Na in amphibole) and geometry (euhedral to anhedral shapes) of the oscillations can be interpreted in terms of subtle fluctuations in P–T during the general prograde subduction‐related metamorphic path. A (near‐) equilibrium model is presented for the formation of oscillations at near peak conditions by means of recurrent dissolution‐growth reaction processes. This model for near‐peak conditions, and the chemical signatures of earlier oscillations (notably in amphibole), suggest that episodes of retrogression (upward movement?) affected parts of the subducting slab. It is proposed that these retrograde episodes record the tectonic rupture of the subducting slab and, probably, of the upper plate mantle, either due to the intrinsic dynamic behaviour of subduction systems or to the effects of the plate‐tectonic rearrangement of the Caribbean region during the Early Cretaceous.  相似文献   

Regional variation in exhumation and strain rate of the high-pressure Sambagawa metamorphic rocks in central Shikoku, south-west Japan   总被引：1，自引：0，他引：1  

K. Yagi  T. Takeshita 《Journal of Metamorphic Geology》2002,20(7):633-647

Regional variation in the P–T path of the Sambagawa metamorphic rocks, central Shikoku, Japan has been inferred from compositional zoning of metamorphic amphibole. Rocks constituting the northern part (Saruta River area) exhibit a hairpin type P–T path, where winchite/actinolite grew at the prograde stage, the peak metamorphism was recorded by the growth of barroisite to hornblende and sodic amphibole to winchite/actinolite grew at the retrograde stage. In the southern part (Asemi River area), rocks exhibit a clockwise type P–T path, where barroisite to hornblende core is rimmed by winchite to actinolite. The difference in P–T path could suggest a faster exhumation rate (i.e. more rapid decompression) in the southern than in the northern part. On the other hand, physical conditions of deformation during the exhumation stage have been independently inferred from microstructures in deformed quartz. Recrystallized quartz grains in rocks from the low‐grade (chlorite and garnet) zones are much more stretched in the southern part (aspect ratio ≥ 4.0) than in the northern part (aspect ratio< 4.0), indicating a higher strain rate in the former than in the latter. These facts may indicate that the exhumation and strain rates are correlated (i.e. the exhumation rate increases with increasing the strain rate). The difference in the exhumation rate inferred from amphibole zoning between the northern and southern parts could be explained by an extensional model involving normal faulting, where the lower plate can be exhumed faster than the upper plate due to the displacement along the fault. Furthermore, the model may explain the positive correlation between the exhumation and strain rates, because the lower plate tended to support more stress than the upper plate.  相似文献   

辽宁瓦房店金伯利岩中铬尖晶石成分的两种分带趋势及其成因探讨     

鲍学昭  关雅先  王公庆  黄顺福 《吉林大学学报(地球科学版)》1995,(4)

首次报道金伯利岩中铬尖晶石的两种成分分带趋势，其中斑晶铬尖晶石以核部富Ｃｒ、边缘逐渐富Ａｌ和Ｆｅ￣（＋３）为特征，该铬尖晶石为金伯利岩岩浆上升过程中形成的；基质铬尖晶石则同上述变化趋势相反，它们是岩浆在温、压增大或母岩在熔融程度增加过程中形成的。根据Ｃｒ＿２Ｏ＿３含量，基质铬尖晶石可分为两类：一是岩浆演化晚期，岩管爆发前槽压过程中结晶的低铬铁尖晶石（Ｃｒ＿２Ｏ＿３＜５４％）；二是来自深源捕虏体的高铬铁尖晶石（Ｃｒ＿２Ｏ＿３＞６０％），本文探讨了它们的形成机制。  相似文献   

小兴安岭地区与加里东期花岗岩类有关的矿床成矿系列   总被引：6，自引：1，他引：6  

韩振新  郝正平  侯敏 《矿床地质》1995,14(4):293-302

加里东期花岗岩类岩浆活动及其有关的成矿作用，在小兴安岭地区形成了一批铁、铜、锌、铅、锡、钼和钨等矽卡岩型和热液型的矿床。这些成因上紧密相关的矿床形成时间相近。不过，在不同的岩浆活动阶段和不同的地质环境中形成的矿床，，其矿化特征又有明显的差别，而且，矿种和矿化类型在空间的分布上，呈现有规律的分带象。本文着眼于研究上述的矿床所处的地质背景、成矿条件和成矿作用，用成矿系列的观点，对矿床进行矿亚系列和矿床  相似文献   

太行山区土岭、石湖金矿区地球化学及其找矿标志   总被引：5，自引：0，他引：5  

杨殿范  刘荣访  李高山  贾克实 《吉林地质》1991,(4)

本文讨论了土岭、石湖金矿区与成矿有关的地质体的地球化学特征及其找矿标志。认为该矿区成矿物质—Au具有多源性;As、Sb、Ag、Au、Cu、Pb、Zn、Co、Ni为找矿指示元素;Hg是远程指示元素,而Au则是直接指示元素。指示元素的轴向分带序列为:As—Ag—Sb—Cu—Zn—Au—Pb—Ni—Co,并以此建立了预测矿体埋藏深度关系式:H=38.790As/Co+442.842 LnH=0.0923Ln[(As.Ag.Sb)/(Au.Co.Ni)]+6.3116  相似文献   

吉林放牛沟硫铁多金属矿床原生地球化学异常特征     

朴寿成  刘树田 《吉林大学学报(地球科学版)》1992,(2)

放牛沟矿床主要成矿元素Zn、Pb并非由地层提供,而是来自岩体深部,通过岩体接触带构造向火山—沉积岩系运移而形成矿床及原生异常的。Zn、Pb、Cu、Ag等元素正异常与Cr、Sr等元素负异常的套合产出是矿床存在的重要标志.矿体、矿组、矿床异常有明显的分带规律,分带性指数从浅部到深部呈规律性变化.根据Ag/Bi可判别前缘、尾晕,利用PbZnAgBa/CuBi可判别矿组和矿床原生异常的剥蚀程度.  相似文献   

应用微晶石英标型特征研究某隐伏铀矿床的垂直分带     

倪师军  金景福 《矿物学报》1992,12(3):243-250

所研究的矿床为一个大型隐伏铀矿床,是华南铀成矿区一个典型的花岗岩型铀矿床。本文重点研究了该铀矿床主成矿阶段微晶石英的标型特征。在矿床垂直方向上,微晶石英的杂质组分、晶胞参数和人工热释光(ATL)性质均显示较大的变化。微晶石英标型特征的这些差异可以作为研究隐伏铀矿床垂直分带的有效手段,并可用于判断其侵蚀截面。  相似文献   

Random field characteristics of seismic zoning map     

Meng-Tan Gao  Hua Pan 《地震学报(英文版)》1993,6(2):437-445

How to test the reasonability of the seismic zoning map with probabilistic means is the most concerned problem. So far, there were no good methods to test zoning map using actual intensity data. Firstly, the author suggest the concept of random field, then proved that the average value of the randomifield is ergodic by using Monte Carlo method, therefor the spatial average tend to be the average of the random field with probability of the zoning map. Thus, a method of testing seismic zoning map with probabilistic means using spatial distributing samples of intensity caused by actual earthquakes was provided. The Chinese seismic zoning map made in 1990 was tested using recent 15 years and 50 years intensity samples. The results shows that this zoning map is reasonable. The method provided in this paper can be used in other circumstance in which random field methods were used. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 53–60, 1993.  相似文献