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大吉山花岗岩人工重砂中的宇宙尘呈黑色,具强磁性,平均粒径为0.206mm,按形态可分为球状、椭球状和不规则状,按成分可分为铁质和硅酸质两种类型。主要矿物有方铁矿、α-Fe、自然铜、钠长石和钾长石。主要组构类型有瘤状突起构造、喷气孔构造、“毛刺”构造、壳层构造、空腔构造、花边构造和脑纹状构造。通过研究得出如下结论:(1)大吉山宇宙尘是低氧逸度条件下高温淬火形成的非平衡结晶产物;(2)宇宙尘的来源与大吉山花岗岩的成因有密切联系,是花岗岩岩源层的残留物;(3)宇宙尘可以作为花岗岩成因指示物。 相似文献
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山西三交区太原组含煤岩系中宇宙尘的发现及其成因探讨 总被引：1，自引：0，他引：1
在扫描电镜下发现的太原组中的宇宙尘的表面显,微构造有皱纹构造、熔蚀构造、瘤状构造、碎裂构造和球粒构造5种,它们是铁质宇宙尘,确系地外星球物质,属于消融型宇宙尘。 相似文献
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河东煤田中部晚古生代含煤岩系中宇宙尘的首次发现及其特征 总被引：3，自引：0，他引：3
宇宙尘系重要的太阳系物质.笔者在利用双目镜、扫描电镜研究河东煤田中部晚古生代含煤岩系沉积岩时,发现了沉积的宇宙尘.可见到的表面显微构造特征有:无规则全晶质构造、晶间孔构造、熔蚀构造、瘤状构造、气孔和空腔构造、球粒构造、皱纹构造和碎裂构造等八种类型。由电子探针测定的化学成分得知,本区宇宙尘有玻璃质、硅酸盐质和铁质三种。它们均与已报道的宇宙尘的化学成分相似。但铁质宇宙尘中的Ir含量高达1.09%,这种“指纹元素”的大量存在,进一步证明了它们确系地外星球物质。 相似文献
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本文研究的宇宙尘,是研究南大地质系研究生傅成义同志送本室三个花岗岩人工重砂样(其中两个改造型的花岗岩)所发现的。两个样品中一个是太古代的混合花岗岩,在其中发现了近百颗黑色磁性球粒;另一个样品是晚侏罗纪的细粒二长花岗岩,发现了大小一千多颗黑色磁性宇宙尘,还有个别褐黑—棕色、灰白色的玻璃质、硅质球粒。这些磁性球粒具有层壳结构、熔蚀结构、空腔构造和气印构造。大多数球粒都包含有亮钢灰色的金属核心(图1)。本文通过双目镜鉴定、反光镜观察测定、X光粉晶分析、电子探针分析,初步对宇宙尘的物理性质、光学性质、化学成分进行了研究。主要通过扫描电镜的微观形态观察、照 相似文献
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昌黎-阜新构造岩浆钼金成矿带,沿NE向断裂带分布有中生代花岗岩体27处,以重熔岩浆花岗岩为主,交代花岗岩次之,包括Ⅰ、A和S型三种花岗岩,分四期侵入,第三期花岗岩伴随有钼金多金属成矿作用,其中的11个不同期次不同类型的花岗岩体中发现有宇宙尘,可分为铁质空心球、铁质实心球和硅酸玻璃球状三种宇宙尘,组成矿物有磁铁矿、蔷薇辉石、石英、刚玉和锥纹石。花岗岩中宇宙尘的发现进一步证明该区花岗岩是壳源产物,而且这种源岩曾经出现在地表,接受宇宙降落物质,而后下沉重熔或交代改造生成花岗岩。 相似文献
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苏北宇宙尘的首次发现及其地质意义 总被引：2，自引：0，他引：2
笔者近几年在苏北古老片麻岩,花岗斑岩,石英斑岩,石英脉,硅化角砾岩,蚀变碎裂岩及第四纪砂砾层中,均发现了一种黑色具磁性的球粒。经形貌特征分析,结构构造鉴定及电镜扫描,x—射线纷晶分析,电子探针,中子活化分析,证明这种磁性球是铁质宇宙尘。但其元素丰度与铁陨石有某些差异。如Ni,Co含量低,贫缺贵金属Os,Ir而富Cu,As、Sb、W等元素。所以推测这种宇宙尘并非是铁陨石消融产物,而可能是流星体(慧星)的消融产物。文中从宇宙尘该区多种岩石中都有产出,探讨了宇宙尘参与地壳物质演化过程,以及演化后宇宙在种类上,数量上,成分上的变化。同时对宇宙尘的降落背景及在解决岩石成因上做了探讨。对其研究无疑是重要的。 相似文献
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宇宙尘似文象结构的图像分析和成因探讨 总被引：2，自引：0，他引：2
宇宙尘较广泛地分布于各地质时代和各种岩石中,它形成在不同的物理化学环境下,因此具有比较复杂的结构构造。本文对产于不同时代、不同岩性岩石中具有似文象结构的宇宙尘进行了广泛的研究,一方面研究Si、Al等元素的赋存状态,另一方面研究这些元素与似文象结构的关系,进一步为它们的成因提供信息。 相似文献
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SONG Tianrui ZHENG Ning LIU Yongqing KUANG Hongwei PENG Nan LI Chao TANG Jigang YAN Qinggao GAO Linzhi ZHU Zhicai XIA Xiaoxu WANG Yuchong 《《地质学报》英文版》2020,94(1):38-56
This study covers cosmic spherules derived from the Mesoproterozoic Dahongyu Formation in the Ming Tombs area, Beijing. The cosmic spherules include iron oxide cosmic spherules, carbonaceous chondrites, and atomic iron “steely bead”-shaped cosmic spherules. The mineral assemblage of silicon carbide, forsterite, zircon, and glass spherules and fragments were picked from melt-silicified carbonate of the Mesoproterozoic Dahongyu Formation (ca. 1625 Ma). Cosmic spherule assemblages are solely discovered from sedimentary rocks in China. Platinum group elements (PGE) were determined for the first time in cosmic spherules and associated minerals. PGE comparative observation between meteorite and cosmic spherules is presented in this study. It is recognized that an extraterrestrial meteorite impact event might have occurred in the Dahongyu Stage. The main evidence is a large number of iron cosmic spherules in silicified oncolitic limestone, and associated cosmic silicon carbide, glass spherules, and fragments, as well as the presence of forsterite. The impact-volcanic crater is characteristic of a big black shale block dropped into the bended silicified limestone. 相似文献
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在吉林省南部元古宇石英岩内发现磁性微球粒３９２枚,根据其产状,形貌及一般特征,微结构和化学组成表明为陨石消融型宇宙尘,由４亚４小类组成一个宇宙尘系列,（１）金属球粒;（２）纯铁球粒,（ｂ）ＦＣＮ型（天然不锈钢）球粒;（２）氧化物球粒（ａ）普通铁质宇宙尘（ｂ）铬铁氧化物球粒;（３）玻璃质球粒;（４）氧化物－金属过渡型球粒,其母体要能是一分异的ＦＣＮ型石－铁陨石质陨星体,核部为ＦＣＮ合金,经消融分异作 相似文献
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Clément Suavet Carole Cordier Luigi Folco Corinne Sonzogni 《Geochimica et cosmochimica acta》2011,75(20):6200-6210
In order to identify the parent bodies of cosmic spherules (melted micrometeorites) with porphyritic olivine (PO) and cryptocrystalline (CC) textures, we measured the oxygen isotopic composition of 15 giant (>800 μm) cosmic spherules recovered in the Transantarctic Mountains, Antarctica, with IR-laser fluorination/mass spectrometry, and we conducted a characterization of their petrographic and magnetic properties. Samples include 6, 8 and 1 spherules of PO, CC and barred olivine (BO) textural types, respectively. Eleven spherules (∼70% of the total: 4/6 PO and 6/8 CC, and the BO spherule) are related to ordinary chondrites based on oxygen isotopic compositions. Olivines in ordinary chondrite-related spherules have compositions Fa8.5-11.8, they are Ni-poor to Ni-rich (0.04-1.12 wt.%), and tend to be richer in CaO than other spherules (0.10-0.17 wt.%). Ordinary-chondrite related spherules also have high magnetite contents (∼2-12 wt.%). One PO and one CC spherules are related to previously identified 17O-enriched cosmic spherules for which the parent body is unknown. One CC spherule has an oxygen isotopic signature relating it to CM/CR carbonaceous chondrites. The majority of PO/CC cosmic spherules derive from ordinary chondrites; this result exemplifies how the texture of cosmic spherules is not only controlled by atmospheric entry heating conditions but also depends on the parent body, whether be it through orbital parameters (entry angle and velocity), or chemistry, mineralogy, or grain size of the precursor. 相似文献
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焦作矿区太原组宇宙尘的发现及其特征 总被引：3，自引：0，他引：3
<正> 宇宙尘的研究,有助于了解太阳系的起源与演化;有助于地层的划分与对比和估计沉积速率等。1876年莫雷(Murray)描述宇宙尘微球粒以来,一些科学家也在深海沉积物中发现了这种磁性微球粒,同时利用现代技术在高空中也收集到微球粒,证实了宇宙尘的存 相似文献
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We have determined the major and trace element compositions of 176 individual microtektites/spherules from the Australasian, Ivory Coast, and North American microtektite and clinopyroxene-bearing (cpx) spherule layers. Trace element contents for up to 30 trace elements were determined by instrumental neutron activation analysis (INAA), and major element compositions were determined using energy dispersive X-ray (EDX) analysis in combination with a scanning electron microscope (SEM). In addition, petrographic data were obtained for the cpx spherules using the SEM and EDX. This is the first trace element study of individual Australasian microtektites, and the data revealed the presence of a previously unrecognized group of Australasian microtektites with high contents of Ni (up to 471 ppm). In previous studies the high-Mg (HMg) Australasian microtektites were thought to be related to the HMg Australasian tektites, but our trace element data suggest that the high-Ni (HNi) Australasian microtektites, rather than the high-Mg microtektites, are related to the high-Mg Australasian tektites. We find that Cenozoic microtektites/spherules from a given layer can be distinguished from microtektites/spherules from other layers as a group, but it is not always possible to determine which layer an individual microtektite/spherule came from based only on trace element compositions. The cpx spherules and most of the microtektites have Cr, Co, and Ni contents that are higher than the average contents of these elements in the upper continental crust, suggesting the presence of a meteoritic component. The highest Cr, Co, and Ni contents are found in the cpx spherules (and low-Si cpx-related microtektites). Unetched to slightly etched cpx spherules have Ni/Cr and Ni/Co ratios that generally lie along mixing curves between the average upper continental crust and chondrites. The best fit appears to be with an LL chondrite. The moderately to heavily etched cpx spherules have values that lie off the mixing curves in a direction that suggests Ni loss, probably as a result of solution of a Ni-rich phase (olivine?). The Ni-rich Australasian microtektites also have Ni values that lie close to mixing curves between the average upper continental crust and chondrites. However, both the cpx spherules and HNi Australasian microtektites appear to have Ir (and to a lesser extent Au) contents that are much too low to have Ni/Ir ratios similar to chondritic values. We have no explanation for the low-Ir and -Au contents except to speculate that they may be the result of a complex fractionation process. The Ivory Coast and North American microtektites do not have high enough siderophile element contents to reach any firm conclusions regarding the presence of, or nature of, a meteoritic component in them. Trace element compositions are consistent with derivation of the Cenozoic microtektite/spherule layers from upper continental crust. The normal Australasian microtektites appear to have been derived from a graywacke or lithic arenite with a range in clay and quartz content. The source rock for the high-Mg Australasian microtektites is not known, but the HMg microtektites do not appear to be normal Australasian microtektites that were simply contaminated by meteorites or ultramafic rocks. The average Ivory Coast microtektite composition can be matched with a mixture of target rocks at the Bosumtwi crater. The average composition of the North American microtektites suggests an arkosic source rock, but with graywacke and quartz-rich end members. However, we could not match the composition of the North American microtektites with lithologies in impact breccias recovered from the Chesapeake Bay impact structure that is believed to be the source crater. Likewise, we could not match the composition of the cpx spherules with mixtures of basement rocks and overlying sedimentary deposits (for which compositional data are available) at the Popigai impact crater that may be the source crater for the cpx spherules. This may be because the cpx spherules were derived, in large part, from clastic surface rocks (sandstones and shales) for which no compositional data are available. 相似文献
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地质记录中的微球粒 总被引：1，自引：0，他引：1
地质记录中的微球粒根据成因可以分为宇宙尘、地外物体撞击成因微球粒、火山成因微球粒、生物成因微球粒、沉积作用微球粒和现代微球形飞灰等。宇宙尘含有丰富的宇宙物质,出现Fe、Ni核心和方铁矿等,具有宇宙尖晶石和宇宙不丰富的元素的亏损是判断宇宙尘的关键特征。撞击事件可以产生近源区的撞击熔融玻璃球和远源区的撞击汽云凝结球两类微球粒,常与其他撞击成因矿物伴生。火山微球粒是在低粘稠度的岩浆岩喷发形成的玻璃质火山灰中,有球形、液滴形和哑铃形的微颗粒。这三种成因的微球粒在各种地层中的赋存对于地层对比和地史事件研究中有着非常重要的意义,为判断和研究不同的地质事件提供了一个很好的媒介,因此长期以来一直是微球粒研究的主要对象。另外,在现代工业生产过程中也可以产生大量微球形飞灰,这些飞灰经常包含非常复杂的表面纹饰和独特的化学组成,比如高的ZnO含量等。 相似文献
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Ahmed El Goresy 《Contributions to Mineralogy and Petrology》1968,17(4):331-346
Numerous magnetic spherules and grains collected from the Greenland ice and suspected of being of cosmic origin were studied microscopically and with the microprobe. Seven types of spherules and grams were recognized.Several magnetite spherules contain metallic cores. The metallic cores of three spherules are composed of nearly pure Fe with traces of Ni. The metallic nuclei of two other spherules contain appreciable amounts of Ni; the nucleus of one of these is composed of a Ni-rich NiFe alloy (96.9% Ni), and that of the other contains 3% Ni. This latter spherule is probably of cosmic origin, perhaps formed in the fusion crust of an iron meteorite. Its magnetic shell contains no detectable Ni.The majority of the spherules consist of magnetite, which is more or less transected by martite lamellae [parallel to {111} planes of the magnetite]. One composite grain of titanomagnetite, ilmenite, hematite, and pyroxene was also found. This grain is of terrestrial origin, probably derived from the metamorphic crystalline complex of Greenland. The mineralogy and chemistry of the observed magnetite spherules and grains are discussed in detail.This work was begun at Smithsonian Astrophysical Observatory, Cambridge, Massachusetts, where it was supported in part by Grant GA-855 from the National Science Foundation, and completed at Max-Planck-Institut für Kernphysik, Heidelberg. 相似文献
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金石滩是大连地区的国家级风景旅游地,在玫瑰园景点的现代沉积物研究中,首次发现了铁质宇宙球粒,而且含量较多,在2.4 kg(<0.5 mm)的砂样中分离出18个宇宙球粒,其大小介于158～423μm,大多数宇宙球粒的表面具有典型的融熔-分凝构造,按其表面化学成分可分为:Fe质、Si-Al-Fe质、Cr-Fe质和Ti-Fe质等4种;笔者特别对其中的Ti-Fe质宇宙颗粒的成分及矿物演变进行了研究,认为宇宙球粒快速冷凝化学分异可在磁铁矿边缘形成钛磁铁矿;对大连、西藏泽当现代沉积物中、太平洋深海现代沉积物中,以及北京十三陵元古宙沉积岩中的宇宙球粒进行了比较,结果表明它们在化学成分上虽有差别,但在颗粒大小和表面结构上是类似的。 相似文献