共查询到20条相似文献，搜索用时 46 毫秒
1.
The GRV 024516 and GRV 024517 meteorite samples collected from Grove Montains,Antactica are ureilite and H5 ordinary chondrite,respectively.Based on the study of mineralogy-petrology,the cosmic-ray exposure ages and gas retention ages of these two meteorites were determinated and calculated.Their cosmic-ray exposure ages are 33.3 Ma,51.7 Ma,and gas retention ages are 1936.8 Ma and 3720 Ma,respectively.The ureilite contains diamond,graphite and amorphous C,which are mainly carrier of noble gases indicating obviously shock metamorphism effects,which induced 40Ar partial loss.The H5 chondrite indicates thermal metamorphism of parent body,its gas retention age fall the range between 3220 Ma and 4510 Ma of the least shocked H5 chondrites 相似文献
2.
中条山涑水杂岩的同位素年代学研究及其地质意义 总被引：2，自引：0，他引：2
中条山是中国重要的铜多金属成矿带,拥有著名的晚太古代"变斑岩型"铜矿峪大型铜矿床和元古代"层控型"胡家峪—篦子沟铜矿床,近年来又在中条山西南段的涑水杂岩中发现以变基性火山岩(斜长角闪岩)为容矿岩石的桃花洞铜矿。为了弄清楚该铜矿的形成时代及其成矿地质背景,利用电感耦合等离子质谱(LA-MC-ICP-MS)方法对桃花洞铜矿容矿围岩—涑水杂岩中的寨子—西姚灰色片麻岩、斜长角闪岩及二长花岗岩进行了同位素年代学研究。结果表明:寨子—西姚灰色片麻岩、斜长角闪岩脉和二长花岗岩中锆石的岩浆结晶年龄分别为(2 625±11)、(2 592±16)、(2 548±15)Ma;岩石中古老继承性锆石的年龄分别为(2 790±15)、(2 773±24)、(2 782±34)Ma;三种不同成生顺序的岩石中均有大于2 700Ma的锆石存在,且年龄相当接近;中条山地区涑水杂岩可能最初形成于太古代。涑水杂岩作为与成矿关系密切的容矿围岩,其成岩时代可以间接指示成矿时代,由此得出赋存在变基性火山岩层中的古火山含矿原岩建造型铜矿有可能是中国最古老的铜矿之一。 相似文献
3.
The colorful satellite image maps with the scale of 1∶100 000 were made by processing the parameters-on-satellite under the condition of no data of field surveying. The purpose is to ensure the smooth performance of the choice of expedition route, navigation and research task before the Chinese National Antarctic Research Expedition (CHINARE) first made researches on the Grove Mountains. Moreover, on the basis of the visual interpretation of the satellite image, we preliminarily analyze and discuss the relief and landform, blue ice and meteorite distribution characteristics in the Grove Mountains.
Key words Grove Mountains, parameters-on-satellite, satellite image, digital mapping, blue ice, meteorites distribution. 相似文献
4.
Thirty-two meteorites were collected in Grove Mountains area, Antarctica, by the 15th and 16th Chinese Antarctic Research Expeditions (CHINARE). Petrography and mineral chemistry of these meteorites are reviewed, among which there are one Martian lherzolite, one eucrite, one ungrouped iron meteorite, and six unequili-brated and twenty-three equilibrated ordinary chondrites. An equilibrated ordinary chondrite GRV 98004 ( H5 ) has an unusually low cosmic-ray exposure age. Meteorite concentrating processes in Grove Mountains area are discussed. In addition, future studies on Grove Mountains (GRV) meteorites are proposed. 相似文献
5.
LA-ICP MS zircon U-Pb dating results of granites from Sawuer Mountains in North Xinjiang, NW China, are reported based on 1:50 000 regional geologic surveys. Zircon U-Pb dating shows that the granitoids have magmatic crystallization age of 320 ±2 Ma. In addition, zircons with ages of 341 ～358 Ma could be subdi- vided into two groups, i.e. , Group 1 with a weighted mean age of 342 + 3 Ma and Group 2 with a weighted mean age of 354 + 2 Ma. The petrology and geochemistry of granitoids from Sawuer Mountains suggest their mixed origin. The granite from Sawuer Mountains occurred in an extensional setting, most probably related to post-orogenic processes during the closure of the Peo-Asian Ocean; namely, represent the tectonic setting shif- ted from compress to post-collisional setting. 相似文献
6.
Influence of Collective Boulder Array on the Surrounding Time-averaged and Turbulent Flow Fields 总被引：1，自引：0，他引：1
Achilleas G.TSAKIRIS A.N.Thanos PAPANICOLAOU Seyed M.HAJIMIRZAIE James H.J.BUCHHOLZ 《山地科学学报》2014,(6):1420-1428
Arrays of large immobile boulders,which are often encountered in steep mountain streams,affect the timing and magnitude of sediment transport events through their interactions with the approach flow.Despite their importance in the quantification of the bedload rate,the collective influence of a boulder array on the approach timeaveraged and turbulent flow field has to date been overlooked.The overarching objective is,thus,to assess the collective effects of a boulder array on the time-averaged and turbulent flow fields surrounding an individual boulder within the array,placing particular emphasis on highlighting the bed shear stress spatial variability.The objective of this study is pursued by resolving and comparing the timeaveraged and turbulent flow fields developing around a boulder,with and without an array of isolated boulders being present.The results show that the effects of an individual boulder on the time-averaged streamwise velocity and turbulence intensity were limited to the boulder’s immediate vicinity in the streamwise（x/d c 〈 2-3） and vertical（z/d c 〈 1） directions.Outside of the boulder’s immediate vicinity,the time-averaged streamwise velocity was found to be globally decelerated.This global deceleration was attributed to the form drag generated collectively by the boulder array.More importantly,the boulder array reduced the applied shear stress exerted on theindividual boulders found within the array,by absorbing a portion of the total applied shear.Furthermore,the array was found to have a ＂homogenizing＂ effect on the near-bed turbulence thus significantly reducing the turbulence intensity in the near-bed region.The findings of this study suggest that the collective boulder array bears a portion of the total applied bed shear stress as form drag,hence reducing the available bed shear stress for transporting incoming mobile sediment.Thus,the effects of the boulder array should not be ignored in sediment transport predictions.These effects are encapsulated in this study by E 相似文献
7.
The Mushroom Stone Forest, which consists of granite boulders looking like mushrooms with flared sidewalls, is located in eastern Guangdong China, and is a famous scenic spot that draws many tourists each year. The Mushroom Stone Forest has been traditionally recognized as a collection of wave erosion landforms and used for the reconstruction of palaeo-sea-level changes along the coastal areas of eastern Guangdong in previous coastal researches. By combining in situ measurements of the aspect,vertical profile and height of boulder sidewalls,palaeo-coastal wave direction estimation, rock density determination, major elemental analysis, and petrographic thin section analysis, this paper presents an alternative origin for the Mushroom Stone Forest.Our results suggest that wave or wind erosion cannot offer a satisfactory explanation for the formation of the Mushroom Stone Forest; The boulders that make up the Mushroom Stone Forest originated from the corestones in the granite weathering crusts of the Little Sangpu Mountain; When the debris of the weathering crust was removed, the corestones are perched on rocky outcrops or half-buried by weathering debris beneath the natural land surface;The flared sidewall (concave vertical profile) of the boulders is a particular form developed in the foot zone of a half-buried boulder through increased chemical weathering beneath the land surface. A recent exposed half-buried boulder found in the study area provides convincing evidence to support this argument. Sea water reached the foot of the Sangpu Mountain during the Holocene transgression, but it merely provided a mechanism to erode the weathering debris from the bottom of the mushroom rocks and enhanced salt weathering that created tafoni on the boulders. These findings demonstrate that the boulders of the Mushroom Stone Forest are not sea stacks and cannot be served as a palaeo-sea-level indicator. 相似文献
8.
Glaciogene sedimentary rocks have been found in modem tills of the Grove Mountains, east Antarctica during the 1998 - 1999 Chinese National Antarctic Research Expedition （CHNARE）. Based on the lithilogic and sedimentary features, these sedimentary rocks are correlated with Cenozoic sedimentary strata of the Pagodroma Group in the neighboring Prince Charles Mountains and the Sorsdal Formation in VestFold Hills. Sedimentary clasts contain sparsely Late Tertiary spores and pollens, including ： Toroisporis （ Lygodiaceae）, Osmunda, Granulatisporites （ Pteridaceae？） , Polypodiaceae, Podocarpus , Araucariaceae, Artemisia , Rhus , Nothofagidites , Proteacidites （Proteaceae） , Quercus , Fraxinoipollenites （ Oleaceae ） , Oleoidearumpollenites（ Oleaceae ）, Operculumpollis, and Tricolpopollenites. Most of the pollen and spores contained in these samples originate from local sources according to the conditions of their preservations as well as correlations with the microfossil assemblages found in the neighboring areas. The majority of the pollen assemblages, as represented by Podocarpus and Nothofagus, belong to the Weddellian biogeocenose, however some exotic components from the old sedimentary basement rocks may have been included during erosion of the proximal ice sheet. If the source areas of glaciogenic sedimentary rocks that bear the pollen and spores are assumed to be local, or in the up glacier areas, the pollen assemblages in these samples might represent an inland flora during a warmer period of the ice-sheet evolutionary history. The finding of the Artemisia and Chenopodiaceae in the pollen assemblages implies that they may belong to late Tertiary （most probably Pliocene）. The absence of diatoms in the samples analyzed may indicate that there are no Cenozoic marine strata in the interior of the east Antarctica beyond the Grove Mountains. The significances of the finding of the Nothofagus in these pollen assemblages are discussed on the basis of current knowledge about the age, distribution and ecological conditions of this kind of fossils found in Sirius Group or other strata outcropped in Antarctica. As a preliminary conclusion, we think that the existence of the Cenozoic glaciogenenic rocks and their pollen assemblages present new evidence for a large scale glacial retreat history in Grove Mountains of east Antarctica, and thus support a dynamic East Antarctic Ice Sheet （EAIS）. This is consistent with the interpretations of Webb et al. （1984）. 相似文献
9.
Progress in study of Chinese Antarctic Meteorites 总被引：1，自引：0，他引：1
This paper reviews and summarizes the Chinese Antarctica meteorite search, classification and research. During the past four antarctic explorations, a total of 9834 meteorites were collected in the Grove Mountains region. Among them, 2431 meteorites were classified by the end of 2008. So far, 684 meteorites have been officially published in the Meteoritical Bulletin, Meteoritical Society, including 2 martian meteorites, 2 eucrites, 6 ureilites, 5 mesosiderites, 1 pallasite, 1 iron and 10 carbonaceous chondrites. Comprehensive studies were carried out on a number of these rare type meteorites. In addition, we propose to continue the meteorite searching project in Grove Mountains and other regions in Antarctica. We also suggest several key topics of the future researches on the Chinese Antarctic meteorites. 相似文献
10.
南极Grove山自然保护区信息系统的设计与实现 总被引：1，自引：0，他引：1
位于东南极Grove山地区的天然地质和独特地貌有助于解决许多重大的科学问题.为了保护该地区特殊的科学价值、美学价值和荒野价值,中国提出了建立南极Grove山自然保护区的设想,如何有效管理该地区的信息资源,为保护区的设立和管理提供决策支持成了一个急需解决的问题.本文介绍了南极自然保护区的研究现状,分析了南极Grove山自然保护信息系统数据特点,以及功能和性能需求,设计了双重模式(C/S模式和B/S模式)三层体系框架(数据层、应用层和表现层)的南极Grove山自然保护区信息系统,在此基础上,采用组件式GIS和Web GIS技术实现了原型系统,从而为Grove山空间数据和专题数据的有效管理,以及自然保护区的决策支持管理,提供了保护区信息交流与共享的平台. 相似文献
11.
1 Introduction The Grove Mountains is located at Princess Elizabeth land in East Antarctica, about 400 km from Zhongshan station and 160 km east of the Mawson Escarpment, consists of a scattered group of mountains and nunataks. The range extends73°-76°E… 相似文献
12.
别也萨麻斯矿床是目前新发现的分布在新疆北阿尔泰以Li矿化为主的花岗伟晶岩型稀有金属矿床,具有独特性和代表性。矿区发育Li-Nb-Ta矿化和Nb-Ta矿化两类伟晶岩,二云母二长花岗岩是含矿伟晶岩脉群的直接围岩。在系统的野外地质特征调查(包括野外露头和钻孔岩芯赋矿岩系、矿化特征、蚀变类型等的详细观察)基础上,对含矿伟晶岩和二云母二长花岗岩开展了LA-ICP-MS锆石U-Pb定年和原位Hf同位素研究。获得锆石206Pb/238U加权平均年龄分别为(151.0±1.8)Ma和(449.0±4.2)Ma,含矿伟晶岩形成于晚侏罗世,二云母二长花岗岩则形成于晚奥陶世。含矿伟晶岩和二云母二长花岗岩的εHf(t)值分别为0.62~1.30和1.35~6.07,二阶段Hf模式年龄为1161~1118 Ma和1345~1037 Ma。含矿伟晶岩的εHf(t)值较花岗岩小得多,二阶段Hf模式年龄与形成年龄的差值较花岗岩大得多,表明两者是阿尔泰造山带在不同演化阶段下的产物。悬殊的年龄差、不同的大地构造背景与不同的形成物源表明别也萨麻斯稀有金属矿床含矿伟晶岩与二云母二长花岗岩在成因上并无联系,近矿花岗岩围岩并非含矿伟晶岩脉的真正母体。 相似文献
13.
We performed a comparison analysis of the variations .in Mercury ( Hg) concentrations and the precipitation proxies ( e. g. , 18 O values and 10 Be concentrations) in the Dome C ice core. The results showed that there were significant correlations between Hg and δ 10O values, 10Be concentrations, indicating that the accumulation rate in Dome C is one of the key factors controlling the variations of Hg concentrations in the past 34 ,000 years, and implying that Hg concentrations in ice core can be used as another reliable proxy of precipitation rate in Antarctica. Based upon the high-resolution δ 18O values, we estimated the variations in mercury deposition flux to Antarctica over the past 34,000 years. The highest mercury deposition flux is about 3. 80 pg cm-2 yr-1 during the Last Glacial Maxium (LGM) as high as 3. 5 times of the mercury deposition flux ( about 1. 08 pg cm -2 yr -1) in Holocene due to the fluctuations in natural mercury emissions such as the oceanic biological emissions. 相似文献
14.
东秦岭华县西沟钼矿床Re-Os同位素年龄及其地质意义 总被引：2，自引：0，他引：2
东秦岭华县西沟钼矿床位于华北陆块南缘老牛山岩体与华山岩体所夹持的EW向长廊中,产出于太古界太华群黑云斜长片麻岩地层内。该矿床已经被确定为中型矿床。西沟钼矿区内构造发育,岩浆活动强烈,展布的多条长石-石英脉、碳酸盐脉型钼矿体主要受近EW向剪切带控制,矿石类型以石英脉型、长石-石英脉型、方解石-石英脉型及蚀变岩型为主。应用Re-Os同位素地质年代学方法测得西沟钼矿床的成矿模式年龄为(206.7±2.8)~(214.7±2.8)Ma,等时线年龄为(212.4±2.8)Ma,属于印支晚期;辉钼矿Re质量分数为(306.6~401.0)×10-6,暗示成矿物质主要来源于上地幔。区域成矿条件对比发现,西沟钼矿床与黄龙铺钼矿床在成矿时代、成因类型等方面具有一致性,矿床类型划归为长石-石英脉、碳酸盐脉型。依据化探异常及初步勘查结果,预测西沟地区深部可能存在有隐伏岩体,具有寻找大型钼矿床的潜力。 相似文献
15.
16.
Petrography and mineral chemistry of ninety-eight ordinary chondrites from Grove Mountains (GRV), Antarctica, were presented and their.weathering effect, shock metamorphism and type distribution patterns were discussed in this study. Among them, six are unequilibrated ordinary chondrites, including 3 H3 and 3 L3; and 92 meteorites are equilibrated ordinary chondrites, including 24 H-group (13 H4, 10 H5, 1 H6), 64 L-group (2 L4, 44 L5, 18 L6) and 4 LL-group (3 LL4, 1 LL5). Most GRV chondrites (>90%) displayed minor weathering effect (W1 and W2). About half of the meteorites experienced severe shock metamorphism. They commonly contain shock-induced melt veins and pockets. These heavily shocked meteorites provide us with natural samples for study of high-pressure polymorphs of minerals. In addition, the Grove Mountains collection seems to have more abundant unequilibrated and L group ordinary chondrites compared to the US Antarctic meteorite collection which were mainly found along the Transantarctic Mountains. 相似文献
17.
Shock effects of 93 Grove Mountains (GRV) ordinary chondrites were studied in this work, including fracture, various types of extinction, and recrystallization of silicates observed under optical microscopy. Shock-induced veins and pockets show various microtextures, decomposition and phase transformation of minerals. The confirmed high-pressure polymorphs of silicates are ringwoodite, majorite, pyroxene glass and maskelynite. Based on the shock effects and assemblages of high-pressure minerals, shock stages of all of 93 GRV chondrites were classified. In comparison with literature, the Grove Mountains meteorites have a higher fraction (23 out of 93) of heavily shocked samples (S4-S5). Most of the heavily shocked meteorites are L group (22 out of 23), except for one H chondrite. The distinct shock metamorphism between H and L groups may indicate different surface properties of their parent bodies. In addition, there is relationship between petrologic types and shock stages, with most heavily shocked samples observed in equilibrated ordinary chondrites (especially Type 5 and 6). 相似文献
18.
豫西甘山第四纪冰斗系统的发现及其与MIS的耦合关系分析 总被引：1，自引：0，他引：1
在调查东亚冷槽西壁冰川遗迹及其海拔梯度的过程中,发现了甘山冰斗系统与磨光面、擦痕、漂砾等冰川遗迹。进而对该冰斗系统进行成因分析的过程中,发现了冰斗系统的"冰斗环退"的形成方式。以此为基础,就甘山冰斗系统与MIS之间的耦合关系进行了对比分析。研究表明,甘山冰斗系统是以"冰斗环退"方式形成的,该冰斗环退系统完整展现了我国东部第四纪冰川作用的过程,对研究冰期的雪线高程、环境演化规律、冰川作用的进退等,都有着极其重要的意义。在"冰斗环退"的研究基础上,发现了对应的"冰斗环进"机制。冰斗环进代表了冰川作用由高向低推进过程,冰斗环退代表了冰川作用由低向高撤退过程。通过影像分析,初步将甘山冰斗系统划分四段,共解析出了50余套冰斗环,冰川作用的时代可追溯到2.56 Ma。根据冰斗的环进、环退特征,进而发现C28冰斗环所对应MIS56,也即1.60Ma,可能为我国第四纪冰川作用过程中的冰进向冰退演化的重要拐点。 相似文献
19.
Donald A. FRIEND 《山地科学学报》2005,2(3):181-192
Introduction Studies on microfabric and macrofabric are common, spanning from the sedimentology of fine grained rock to fabric analyses of glacial and periglacial deposits. These studies generally focus on one deposit that is all the same age. This study is unique in that identical measures of fabric were taken on a series of like deposits on the steep slopes (~25° to ~35°) of rhyolite domes in eastern California (Figures 1 and 2) whose maximum possible age stretches over a one-million-year… 相似文献
20.
The impact effect of boulder within debris flow is the key factor contributing to peak impact as well as to the failure of debris flow control work. So accurate measuring and calculating the impact force of debris flow can ensure the engineering design strength. However, limited to the existing laboratory conditions and piezoelectric sensor performance, it is impossible, based on the conventional measurements, to devise a computing method for expressing a reliable boulder impact force. This paper has therefore designed a new measurement device according to the method of integrating Fiber Bragg grating (FBG) and reinforced concrete composite beam (RCB) for measuring the impact force of debris flows, i.e. mounting FBG on the axially stressed steel bar in the composite beam at regular intervals to monitor the steel strain. RCB plays the role of contacting debris flow and protecting FBG sensors. Taking this new device as the experimental object, drop testing is designed for simulating and reflecting the boulder impact force. In a series of impacting tests, the relationship between the peak dynamic strain value of the steel bar and the impact force is analyzed, and based on which, an inversion model that uses the steel bar strain as the independent variable is established for calculating the boulder impact force. The experimental results show that this new inversion model can determine the impact force value and its acting position with a system error of 18.1%, which can provide an experimental foundation for measuring the impact force of boulders within the debris flow by the new FBG-based device. 相似文献