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1.
INDIA/ASIA CONVERGENCE AND HIMALAYAN SHORTENING   总被引:1,自引:0,他引:1  
INDIA/ASIA CONVERGENCE AND HIMALAYAN SHORTENING  相似文献   

2.
As a widely‐developed mineral in various types of rocks, pyrite features important geological information such as temperature and pressure during its formation and evolution (An et al., 2014; An et al., 2018). It is an important geological formation for studying the origins of rocks, mineralization, and deposits (Xue et al., 2014; An et al., 2016). The study of the genesis of gold deposits is a research hotspot in current geology and mineral deposits not only because of high economic value, but also because of important practical significance (An et al., 2017; Yang et al., 2014). Shandong Zhaoyuan, as the third largest gold production area in the world, has important research significance of the origin and generation of gold‐bearing minerals (Xue et al., 2014; Wen et al., 2014). In this study, pyrite from augen granite (figure 1a), syenite (figure 1b), basite (figure 1c) and gold ore (figure 1d) at Zhaoyuan gold deposit Shandong Province, was selected as the research object. The morphological and structural micro‐fabrics were analysed by polarized light microscopy (PLM) and Raman spectroscopy to reveal the source and process of gold further.  相似文献   

3.
CHRONOSTRATIGRAPHY,SEDIMENTATION AND EVOLUTION OF THE XIGAZE FOREARC BASIN: IMPLICATIONS FOR DYNAMIC EVOLUTION OF THE YARLUNG ZANGBO SUTURE ZONE1 All埁greCJ,CourtillotV ,TapponnierP ,etal.StructureandevolutionoftheHimalaya Tibetorogenicbelt[J] .Nature,1984 ,30 7:17~ 2 2 . 2 CoulonC ,MaluskiH ,BollingerC ,etal.MesozoicandCenozoicvolcanicrocksfromcentralandsouthernTibet:3 9Ar 40 Ardating ,petrotogicalcharacteristicsandgeodyn…  相似文献   

4.
浙江中生代火山岩的时代长期以来存在不同意见,主要分岐为浙江磨石山群和浙西建德群时代窨是晚侏罗世、早白垩世、抑或晚白垩世。Lapierre等(1997)的一文中据两条Rb-Sr等时线年龄,给出了如下论断;浙西火山活动(建德群)时代为124Ma,划归为第一幕第一次岩浆事件;浙东(磨石山群)时代为97Ma,划归为第一幕第二次岩浆事件,而第二幕岩浆事件(指永康群)时代〈97Ma,本文就Lapierre等文  相似文献   

5.
The main objective of this work was to define directions and principal features of the evolution of volcanism and sedimentation in Early Precambrian active volcanic zones. Analysis of reconstructed type sections of intensely metamorphosed and greenstone (sedimentary-volcanic) complexes revealed a general similarity of their structure and universal presence of two principal (contrast and differentiated) volcanic associations that replace each other from the bottom to top (Lazur, 2006). Volcanic complexes are crowned with significantly sedimentary sequences and the manifestation of bimodal (basalt-rhyolite) or acid (dacite-rhyolite) volcanism (Luchitskii et al., 1982). Our work is based on specific rock complexes, for which the primary nature of intensely metamorphosed Early Precambrian rocks has been reconstructed by geological, mineralogical, geochemical, and other methods (Lazur, 1986; Rosen et al., 2005).  相似文献   

6.
GEOMORPHIC EVIDENCES FOR CENOZOIC UPLIFT IN THE EASTERN MARGIN OF QINGHAI—TIBET PLATEAU  相似文献   

7.
<正>This study aims to uses paleomagnetic and anisotropy of magnetic susceptibility(AMS)methods to recognize the initial deposit position and to track the paleoflow at the origin of an iron skarn-related deposit.The Yamansu deposit is located in eastern Tianshan(Charvet,2007).This province has a substantial mining potential for Fe–(Cu)skarn,Cu–Ni and V–Ti orthomagmatic deposits,and orogenic Au lodes(Branquet et al.,2012;Zhang et a.,2005;Mao et al.,2005).Recent publication dates the Yamansu deposit at 323 Ma,and uses this deposit to define a model of Submarine Volcanogenic Iron Oxide(SVIO)deposits(Hou et al.,  相似文献   

8.
元谋盆地的新第三纪地层   总被引:4,自引:1,他引:3  
宗冠福 《地层学杂志》1996,20(2):138-145
元谋北部芝麻地段新发现的动物化石层位相当于小河组下部的湖相地层,据之将小河组分为上下两部分,并进一步探讨元谋盆地含古猿动物化石层的地质时代。  相似文献   

9.
LOW TEMPERATURE DATING OF HIGH MOUNTAIN ROCKS:(U-Th)/He AGES FROM HIGHER HIMALAYAN SAMPLES, EASTERN NEPAL1 HouseMA ,WernickeBP ,FarleyKA .DatingtopographyoftheSierraNevada ,California ,usingapatite (U Th) /Heages[J].Nature,1998,396 (5 ) :6 6~ 6 9. 2 HubbardMS ,Harrison .4 0 Ar/ 3 9ArageconstraintsondeformationandmetamorphismintheMainCentralThrustzoneandTibetanSlab ,EasternNepalHimalaya[J].Tectonics,1989,8(4) :86 5~ 880 . 3 HubbardMS …  相似文献   

10.
11.
The U-Pb zircon dates obtained for the Sutara (480 ± 4 Ma), Kabalinskii (471 ± 10 Ma), and Durilovskii (461 ± 5 Ma) massifs reliably confirm an Early Proterozoic orogenic event, which took place after granulite metamorphism at approximately 500 Ma (Wilde et al., 2003) in the Lesser Khingan (Jiamusi) terrane. The rocks emplaced most shortly after the main metamorphic event are the granites of the Sutara Massif and leucogranites of the Kabalinskii Massif, whose geochemistry is close to that of collision granites. The quartz diorites and subalkaline granites of the Durilovskii Massif, whose geochemistry suggests their origin in a postcollision environment with the participation of an enriched mantle source, were emplaced longer after metamorphic event and after the aforementioned massifs.  相似文献   

12.
TWO TYPES OF CENOZOIC HIGH-K MAGMATINSM IN EASTERN TIBET:IMPLICATIONS FOR THE NATURE OF MANTLE SOURCES1 ArnaudNO ,VidalP ,TapponnierP ,etal.ThehighK2 OvolcanismofnorthwesternTibet:geochemistryandtectonicim plications[J] :EarthPlanetSciLett,1991,11:351~ 36 7. 2 DengW .CenozoicvolcanicrocksinthenorthernNgaridistrictoftheTibet Discussionontheconcurrentsubduction[J] .Ac taPetrolSinica ,1989( 3) :1~ 11. 3 HarrisonTM ,LeloupPH ,RyersonFJ,…  相似文献   

13.
Loesses of the Lower Mississippi Valley (LMV) are world-famous. Sir Charles Lyell (1847), Hilgard (1860), Stafford (1869), Call (1891) and Mabry (1898), thought the LMV loess was a single water deposit although “double submergence” was noted by Call (1891) and Salisbury (1891). Shimek (1902) and Emerson (1918) recognized LMV loess as a wind deposit which came from the valley. Although wind-deposited loess gained wide acceptance, Russell (1944a) published his controversial theory of “loessification” which entailed weathering of backswamp deposits, downslope movement and recharge by carbonates to form loess. Wascher et al. (1947) identified three LMV loesses, mapped distributions and strongly supported eolian deposition. Leighton and Willman (1950), identified four loesses and supported eolian deposition as did Krinitzsky and Turnbull (1967) and Snowden and Priddy (1968), but Krinitzky and Turnbull questioned the deepest loess. Daniels and Young (1968) and Touchet and Daniels (1970) studied the distribution of loesses in south-central Louisiana. West et al. (1980) and Rutledge et al. (1985) studied the source areas and wind directions which deposited the loesses on and adjoining Crowley's Ridge. B.J. Miller and co-workers (Miller et al., 1985, 1986, Miller and Alford, 1985) proposed that the Loveland Silt was Early Wisconsin rather than Illinoian age and advanced the name Sicily Island loess. They proposed the underlying loess was Illinoian and advanced the name Crowley's Ridge. We termed the loesses, from the surface downward, Peoria Loess, Roxana Silt, Loveland/Sicily Island loess, Crowley's Ridge Loess and Marianna loess. Researchers agree that the surfical Peoria Loess is Late Wisconsin and the Roxana Silt is Late to Middle Wisconsin, but little agreement exists on the age of the older loesses. Pye and Johnson (1988) proposed Early Wisconsin for the Loveland/Sicily Island. McKay and Follmer (1985) suggested this loess correlated with a loess under Illinoian till. Clark et al. (1989) agreed on Crowley's Ridge, but suggested the Loveland/Sicily Island loess on Sicily Island was older. Mirecki and Miller (1994) and Millard and Maat (1994) suggested an Illinoian age for the Loveland/Sicily Island loess. Miller and co-workers suggested, as did Pye and Johnson (1988), an Illinoian age for the Crowley's Ridge loess. McKay and Follmer (1985) suggested it correlated with a loess under “Kansan” till. Stratigraphy indicates the Marianna is the older of the five loesses.

Researchers identified loess on both the east and west side of the LMV as well as on higher terraces within the valley. Many researchers assumed unaltered loesses were commonly yellowish brown, and silts or silt loams (West et al., 1980; Miller et al., 1986). The nonclay fraction of unweathered LMV loesses was dominated by quartz followed * Corresponding author. by carbonates, mainly dolomites, followed by feldspars, and micas. Clays were dominated by montmorillonite followed by micaceous minerals, kaolinite and vermiculite (Miller et al., 1986). Soils in the Crowley's Ridge loess are most developed, followed by the soils in the Loveland/Sicily Island which are more developed than the modern soils in the Peoria Loess. Soils in the Roxana and Marianna loesses are least developed and the Farmdale Soil of the Roxana is the weaker of the two (Miller et al., 1986). There is certainly overlapping range in the degree of soil development in the various loesses.  相似文献   


14.
<正> 我国寒武-奥陶系界线的研究在20年代就已涉及(孙云铸,1923),周志毅、张进林(1978)认为我国北方寒武-奥陶系的界线应该划在上寒武统的Mictosaukia orientalis组合与下奥陶统的Onychopyge-Leiostegium组合之间;并且认为这条界线大致可与澳大利亚昆士兰上寒武统Payntonian顶部的Mictosaukia perplexa带与下奥陶统Datsonian底部Cordylodus proavus带之间的界线进行对比。周志毅、王志浩等(1984)根据三叶虫、  相似文献   

15.
青藏高原已识别出柴北缘、南阿尔金和高喜马拉雅三条超高压变质带。这些超高压变质带提供了一个不可多得的研究超高压变质岩石形成和折返的机会。柴北缘超高压变质带位于阿尔金断裂的东边,是柴达木—东昆仑地体与祁连—阿尔金微地体和阿拉善—敦煌地体碰撞的产物,由榴辉岩、石榴石橄榄岩和含柯石英片麻岩组成,榴辉岩形成时代500~440Ma,峰期超高压变质年龄440Ma。南阿尔金超高压变质带位于阿尔金断裂带的西边,以产出榴辉岩和石榴石橄榄岩为特征,榴辉岩形成时代为500Ma。南阿尔金超高压变质带被认为是柴北缘超高压变质带的西延,两者被阿尔金断裂左旋位移约400km。阿尔金断裂是巨大的深度>200km的岩石圈走滑断裂,断裂的活动时代至少早到240~220Ma,认为走滑过程中伴随的隆升作用有可能为柴北缘和南阿尔金超高压变质岩石的折返和出露地表做出了贡献,其中阿尔金断裂起到了类似剪刀型断裂的作用。高喜马拉雅超高压变质带在巴基斯坦和印度被发现,以榴辉岩中含柯石英或金刚石为特征,榴辉岩的超高压变质年龄为46Ma,表明超高压变质岩石发生在雅鲁藏布江缝合线关闭后并快速折返。喀喇昆仑断裂走滑过程中伴随的抬升作用则可能对高喜马拉雅地区超高压变质岩石的折返和出露地表做出贡献。在中国东部出露的大别—苏鲁超高压变质带被巨大郯庐断裂左旋走滑位移约500km,可以看作是走滑作用伴随的抬升运动对超高压变质岩石的最后折返和出露地表做出重要贡献的又一例证。青藏高原的隆升通常被认为是印度板块和欧亚大陆新生代以来的碰撞结果。根据高原北部断裂的时代、火山活动和沉积盆地的形成,我们提出高原的隆升是两次俯冲碰撞的结果。第一次发生在中特提斯班公湖-怒江洋盆在白垩纪时期的关闭,其时由于北部来自塔里木盆地和北中国板块及东部来自太平洋板块俯冲产生的抵柱效应,高原北部开始隆升;第二次发生在印度板块的新生代俯冲碰撞作用,造成高原的整体抬升,由此可以解释高原北部平均海拔(5000m)要高于高原南部(平均海拔4000m)。  相似文献   

16.
王志辉  吕庆田 《地球学报》2017,38(S1):79-82
不同于油气藏能源大多产于沉积地层之中, 金属矿成矿部位的地质条件要更为复杂多变。通常情况下矿体表现为不规则形状, 且连续性较差, 难以满足现有地震反射波法所以依据的镜面反射条件(徐明才等, 2009)。不同的围岩地震地质条件差异很大, 甚至同一种岩性受到蚀变、构造作用的影响, 表现出不同的阻抗特征, 当围岩与矿体间的波阻抗差异较小, 难以形成有效的反射波。在控矿构造方面, 通常大规模的构造对成矿具有控矿、控岩作用, 而与成矿部位密切相关的一般是小规模的断裂, 反射波较难识别。根据菲涅耳带理论, 当地质体的尺度小于地震波的一个波长时, 反射地震成像精度会骤降, 而来自这些小尺度、非均匀地质体产生的绕射波和散射波成像较反射波成像具有明显的高分辨率、甚至超高分辨率。利用绕射波成像能够探测和识别地下重要的构造信息, 如破碎带、断层、尖灭点、礁体边界、次火山岩、小尺度的侵入体、不规则盐丘体, 以及其他不连续的地质体(Karimpoul et al., 2015)。考虑金属矿围岩及控矿构造复杂, 矿体几何尺寸较小、形状不规则, 容易产生绕射波, 理论上利用地震绕射波识别这些地质体较反射波更具优势。  相似文献   

17.
GEOCHEMISTRY OF THE PLIOCENE SHOSHONITIC ROCKS FROM OIYUG BASIN, CENTRAL TIBET  相似文献   

18.
Reappraisal of the palaeomagnetic data previously published about the West African Craton and their comparison with the most recent information obtained on doleritic dykes and stromatolite-bearing formations allow us to propose, after a critical examination of the old geochronological data, a new path for the West African Craton between 2200 and 700 Ma. This path has been compared with that of eastern China (which can be simply divided into a northern and a southern China block) between 1400 and 700 Ma. We can observe that these two blocks show a common path before their accretion to the Rodinia super-continent. These two blocks, which were located close the equator and at the outboard of Rodinia at about 1000 Ma, were also characterized by identical stromatolitic assemblages. This result shows that West Africa and Eastern China represented the antipodal continental margins of Rodinia. One can also deduce from our data that the accretion of Rodinia mainly resulted from north–south-oriented displacements. To cite this article: J.-P. Lefort et al., C. R. Geoscience 336 (2004).  相似文献   

19.
在对区内太古宙地层的原岩性质、大的层序、同位素地质测年值的地质意义 (主要是 H2 O、CO2 流体作用在变质作用中能否造成同位素的开放及 TDM值能否反映为变质年龄 )等众多认识分歧进行剖析的基础上 ,将其自下而上划分为桑干岩群、集宁群、单塔子群、红旗营子群 (或称乌拉山群 ) ,其时代依次归属中太古代早期 (330 0—30 0 0 Ma)、晚期 (30 0 0— 2 80 0 Ma)及新太古代早期 (2 80 0— 2 6 5 0 Ma)、中期 (2 6 5 0— 2 5 6 0 Ma)  相似文献   

20.
通过对宁夏固原新生代寺口子剖面的古地磁年代研究,获得该剖面始新统寺口子组共记录的15个正极性和14个反极性,可以与标准极性柱C21n—C11n.1n段进行很好的对比,通过多种地质资料综合分析,确定年龄为47.906—29.401Ma。这一年龄区间正好与现今鄂尔多斯盆地周缘其他新生代断陷盆地(如渭河盆地、银川盆地等)接受沉积的时代基本一致,宁南盆地的发育与这些周缘新生代断陷盆地很可能具有相同的区域地球动力学环境和盆地属性。  相似文献   

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