基于JERS-1雷达干涉测量的格罗夫山冰盖信息提取

东南极格罗夫山地区是由我国科学家最新发现的南极内陆冰盖陨石富集地。本文采用该地区1996年三个时相的JERS-1合成孔径雷达(SAR)原始数据,进行了成像和干涉处理;分析了该地区的雷达图像特征,干涉条纹图与冰面地形、干涉基线(时相、空间)和冰川流动的关系,干涉相干性与基线和冰面变化的关系;定性地揭示了格罗夫山地区冰流的模式,发现了存在于角峰群内部的冰流。此外,本文还分析了该地区干涉去相干的主导因素。     

南极格罗夫山核心区冰下地形测绘

格罗夫山地区位于中山站和冰穹A之间,是中国进行南极内陆科学综合考察的重点区。我们先后组织过5次格罗夫山地区的考察工作,开展了地质构造、古气候环境、陨石、冰盖运动监测、基础测绘和气象观测等多学科考察研究。2010年中国第26次南极科学考察期间,格罗夫山考察队利用专业探地雷达对格罗夫山东部核心区进行了冰下地形测绘工作。本文利用野外采集的测量数据(GPS/GPR数据),经数据处理后,利用专业的制图软件Corel Draw首次绘制出了格罗夫山核心区两幅冰下地形图,初步揭开了这一区域冰原岛峰冰下的地貌形态,对于今后研究整个格罗夫山地区真实的基岩地貌和可能存在的上新世古冰下沉积盆地具有探索性意义。本文还对哈丁山-萨哈罗夫岭间横截面进行分析,发现这两个冰原岛峰之间的槽谷形态已经发育成熟。     

Grove Mountains （GRV） 024237： A new ureilite from Antarctica

Ureilites share the characteristics of differentiated meteorites and of primary chondrites. GRV 024237 is a ureilite, which was found in the 19th Chinese National Antarctic Research Expedition （CHINARE）, at the No. 4 moraine, Grove Moun- tains, Antarctica. GRV 024237 consists mainly of coarse-grained olivine （60 vol%）, pigeonite （30 vol%） and opaque minerals （10 vol% ）. Tri-junction texture between olivine and pigeonite is common. Carbonaceous materials with minor amounts of troilite and nickel-iron metal were observed as interstitial phases. The Fa value of olivine composition varies from 6.2 to 16.8 from rim to core, but pyroxene is homogeneous in composition, with Fs 14.0 to 15.5. Both olivine and pyroxene have normal extinctions. Net-like iron or limonite veins filled in the fractures of olivine and pyroxene, and no diamond was observed. Based on petrographic and mineralogical features, GRV 024237 is a Type I and Group 2 monomict ureilite.     

前言

除了月球外,人类尚无法直接通过航天器获得太阳系其他天体的岩石样品,直到目前,采集降落到地表的陨石是获得地外岩石样品的唯一手段.陨石保存了太阳星云凝聚、行星堆积、地球等类地行星熔融分异等全部过程的信息.同地球上其他资源相比,陨石极为稀少而珍贵.自1969年日本南极考察队在南极大陆和山脉的蓝冰上发现9块陨石以来,人们认识到南极冰盖有利于陨石的长期保存,并存在陨石的独特富集机制,日本、美国、中国、欧盟等各国南极考察队共在南极大陆找到了约40000块陨石.南极大陆成为地球上迄今为止发现陨石最集中的区域.     

Progress in study of Chinese Antarctic Meteorites

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.     

Petrography and Mineral Chemistry of 4 Carbonaceous Chondrites from the Grove Mountains, Antarctica

Petrography and mineral chemistry of four carbonaceous chondrites (GRV 020017, GRV 020025, GRV 021579, GRV 022459) collected from the Grove Mountains (GRV), Antarctica, were reported here. All four chondrites are unequilibrated, as indicated by well shaped chondrules and the chemical variations of olivine and low-Ca pyroxene. The modal abundance ratio of matrix/chondrule are 2(GRV 020017), 2.8(GRV 020025), 1.2(GRV 021579), 1(GRV 022459). GRV 022459 has the largest chondrules(0.6-2.0mm). A total of 30 Ca-Al-rich inclusions were found in the four meteorites. Most inclusions were highly altered, with abundant phyllosilicates in the inclusions of GRV 020017 and GRV 020025. On the base of petrography and mineral chemistry, these chondrites are classified as CM2 (GRV 020017 and 020025), CO3 (GRV 021579) and CV3 (GRV 022459).     

Shock metamorphism of ordinary chondrites from Grove Mountains, Antarctica

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).     

我国首批回收的四块南极陨石类型的确定

中国第15次南极考察队于1999年元月在格罗夫山实施首次考察时回收了四块陨石，填补了我国南极陨石回收的空白。根据国际陨石协会命名委员会新回收陨石的命名原则，这些陨石已分别命名为GRV98001，GRV98002，GRV98003和GRV98004。根据初步岩石、矿物以及全岩化学分析，这四块陨石分别属于石质球粒陨石（GRV98001），L5型球粒陨石（GRV98002），H4型球粒陨石（GRV98004）和极细粒八面体缺陨石（GRV98003）。