PETROLOGY OF IGNEOUS LITHIC CLASTS FROM POLYMICT EUCRITES ALHA76005 AND ALHA77302

A total of seven lithic clasts from the polymict eucrites ALHA76005 and ALHA77302 have been studied petrographically and analyzed with the electron microprobe. All clasts are composed predominantly of pyroxene and plagioclase, ± ilmenite, troilite, Fe-Ni metal, mesostasis, and silica. Pyroxene compositions in unequilibrated clasts and clast bulk compositions, calculated by modal recombination, indicate that the clasts originally crystallized under similar conditions and that they may be genetically related to each other by fractionation of pigeonite and plagioclase.     

THE NOMENCLATURE OF POLYMICT BASALTIC ACHONDRITES

The subgroups within the basaltic achondrite suite are defined using the structural criterion of Wahl (1952). The ‘monomict’ meteorites are samples of a single lithology while the polymict meteorites are those containing two or more lithologies. The ‘monomict’ subgroups eucrites, cumulate eucrites and diogenites are subdivided into both brecciated and unbrecciated meteorites. The polymict achondrites sample a petrological-compositional continuum that contains both mafic and ultramafic rock types and may be subdivided into several groups. Two groups of polymict basaltic achondrites, the polymict eucrites and howardites are separated using an arbitrarily defined criterion. The recommended criterion is based on the amount of magnesian ortho-pyroxenite (diogenite) component in the meteorite. Howardites contain more than 10% and polymict eucrites contain less than 10%. The criteria proposed (perhaps with minor variations), appear to reconcile the ambiguities caused by the polymict eucrites. These meteorites, using earlier structural criteria, are howardites, but using mineralogical-chemical criteria are eucrites. As a subgroup of the polymict achondrites, their relationship with the howardites is clear, and the preservation of the term ‘eucrite’ in their name highlights their modal affinity to the monomict eucrites.     

MINERALOGY AND PETROLOGY OF THE YILMIA ENSTATITE CHONDRITE

Yilmia, a new enstatite chondrite contains moderately well defined radiating and granular chondrules. The plagioclase to enstatite ratio is appreciably higher within than outside of the two granular chondrules in our microprobe sections. Osbornite was observed within the granular chondrules, but not in the rayed chondrules or surrounding matrix Major phases include enstatite, plagioclase (Ab₈₀ An₁₆ Or₄), silica, silicon-rich kamacite and titanian troilite. Minor phases are many and varied: sinoite, silicon-rich taenite, schreibersite, graphite, osbornite, oldhamite, “normal” and zincian daubreelite, ferroan alabandite and a new FeZnMn monosulfide The new mineral (Fe_.538 Zn_.246 Mn_.159 Mg_.004 S) closely resembles albandite and could easily have been overlooked in other meteorites unless a microprobe was used. A new form of oldhamite was also found. Indarch oldhamite, analyzed for comparative purposes, consists of two similar but distinct species: Ca_.96 Mn_.005 Mg_.04 Fe_.01 S and Ca_1.000 Mn_.004 Mg_.02 Fe_.005 S. These have not been reported from other meteorites Based on its mineralogy and texture this is a type II (E6) enstatite chondrite that is transitional toward the intermediate type (E5). It is unique in its mineralogical complexity, abundance of taenite, diversity of zincian minerals and monosulfides, and restriction of osbornite to certain chondrules     

PETROLOGY AND CLASSIFICATION OF THE GARRAF,SPAIN CHONDRITE

Microscopic and electron microprobe studies indicate that the Garraf meteorite is a highly-recrystallized chondrite of petrologic type 6. Olivine (Fa24.7; PMD 1.1) and low-Ca pyroxene (Fs20.9; PMD 1.1) compositions indicate that it belongs to the L-group. Based on contents of noble gases, pervasive fracturing of silicates, common undulose extinction of olivine and plagioclase, and the lack of melt pockets and maskelynite, we place Garraf into shock facies b. We conclude that Garraf is a highly recrystallized L6b chondrite that, after recrystallization, was cataclased and comminuted by shock.     

多条太阳光球FeI线在磁场中形成及形成深度的综合分析(Ⅰ)

针对多通道滤光器太阳磁场望远镜的磁场观测定标及掌握(所采用的)谱线特征之需要,取VAL宁静太阳大气模型计算了7条Fel光球线的Stokes轮廓、形成深度、贡献函数分布,从而较为系统地对多条反常及正常Zeeman线的特征及性质作出了分析与总结,解释了在磁光效应影响下Stokes Q,U参量的形成深度曲线在近线心区域处出现陡峭峰值的原因。     

THE Mg-Cr RELATIONSHIP IN ACHONDRITES AND IN THE SILICATE FRACTION OF MESOSIDERITES,AND ADDITIONAL OBSERVATIONS ON EUCRITES

New data are used to confirm the positive correlation between Mg and Cr in howardites and eucrites, and the identity of the Mg/Cr ratio in the two meteorite groups is established, provided Chaves is treated as an anomalous howardite. Macibini, usually classed as a eucrite, has higher contents of Mg and Cr than all but the cumulate eucrites; the suggestion is made, on the basis of its polymict character, the wide compositional range of its constituent clasts, and its bulk chemistry, that it should be re-classified as a howardite. The Mg-Cr relationship in diogenites is one of almost constant Mg but extremely variable Cr. The “average diogenite” plots fairly close to the trend established for the howardites and eucrites, indicative of the genetic link between these three meteorite classes. The silicate fractions of nine mesosiderites studied do not show a close coherence of Mg and Cr. With the exception of Patwar, they contain more Cr than howardites and eucrites, and exhibit greater variation of Cr relative to Mg. The general lack of clear inter-element trends in these silicate fractions suggests that they had a more complex origin and evolution than the silicates of the achondrites. Preliminary results of quantitative computer modeling of major and trace elements in the eucrites indicate that about 32 percent fractional crystallization of a eucritic liquid of the composition of Sioux County yields a residual liquid similar to Nuevo Laredo; the cumulate produced has the approximate composition of the cumulate eucrite Moama. These results are in agreement with the model developed by Consolmagno and Drake (1977), using the rare earth elements, for a corresponding stage in the solidification of an initial eucritic liquid produced by equilibrium partial melting of the source region of the parent body (Stolper, 1977). Plotting of the Ti concentrations of the meteorites studied against their Fe/Fe+Mg ratios supports Stolper's idea that the eucrites and the Mg-rich achondrites do not lie on the same liquid line of descent, and shows that the mesosiderite silicates do not conform to either trend.     

GENESIS OF THE CUMULATE EUCRITES SERRA DE MAGÉ AND MOORE COUNTY: A GEOCHEMICAL STUDY

Major, minor and trace element abundances have been determined by instrumental neutron activation analysis (INAA) in whole rock and plagioclase separates of Serra de Magé (SdM). The whole rock contains 52% normative plagioclase and its chondritic normalized REE abundance pattern shows a large Eu anomaly, dominated by the plagioclase REE distribution, and nearly unfractionated La-Sm and Sm-Lu abundances. The plagioclase separates contained ～ 6% pyroxenes and exhibited a typical plagioclase REE distribution. The REE abundances in the derivative equilibrium magmas from which SdM and Moore County (MC) plagioclases crystallized have been estimated from the plagioclase data and the plagioclase mineral/liquid partition coefficients. The REE distributions in possibly earlier parental magmas were calculated by assuming that various degrees of plagioclase and pigeonite (plagioclase/pigeonite = 1) fractional crystallization had been operative prior to the crystallization of SdM and MC. The calculated La/Sm and Sm/Yb ratios for the earlier magmas are essentially the same as the equilibrium magmas over a wide range (10–95%) of the assumed fractional crystallization. Considering the REE distributions and the Fe/Fe+Mg ratios, calculation shows that there is no simple genetic relationship between MC and SdM via fractional crystallization processes. A hypothesis for the derivation of these cumulate eucrites in the plutonic environment from residual diogenitic liquid, which was produced by the extensive partial melting of an eucritic source material followed by the crystallization of diogenite, also fails to account for the fractionated REE patterns calculated for the equilibrium and the possible parental magmas for either SdM or MC. Equilibrium non-modal partial melting calculations indicate that SdM and MC could be genetically related by a factor ～ 6 difference in the degrees of partial melting from a similar source material. However, this common source material which should contain > 30% high-Ca clinopyroxene and has a chondritic normalized La/Yb ～ 3, is different than that proposed for the non-cumulate eucrites.     

MINERALOGY,PETROLOGY AND CHEMISTRY OF THE MESSINA (ITALY) CHONDRITE

The meteorite which fell near Messina, Italy, on 16 July 1955 is a typical olivine-hypersthene (L-group) chondrite. Its mineralogical composition is: olivine (Fa24), orthopyroxene (Fs20) with some polysynthetically twinned clynopyroxene, plagioclase (An10) and merrillite. Opaque phases present are: copper, kamacite, taenite, plessite, chalcopyrrhotite, mackinawite, troilite and chromite. The stone contains abundant chondrules. The matrix consists chiefly of broken chondrules with tiny fragments of crystals and rare amorphous material. Chondrules form more than 42% of the meteorite by volume. Some unusual features of the fabric of this meteorite include silicate grains showing deformation; silicates with fusion spots of dark glass containing blebs of metallic iron; iron and troilite with marginal fusion yielding globules and droplets sometimes showing flow structures. The classification of this chondrite is confirmed by bulk chemical analysis.     

MINERAL INCLUSIONS IN MUONG NONG-TYPE INDOCHINITES: IMPLICATIONS CONCERNING PARENT MATERIAL AND PROCESS OF FORMATION

Mineral inclusions have been recovered from 11 Muong Nong-type indochinites by heavy liquid separation of crushed and sieved (74–149 μm) specimens. The mineral inclusions were identified by x-ray diffraction analysis and energy dispersive x-ray analysis. The phases identified include zircon, Al₂SiO₅ (corundum plus SiO₂), rutile, chromite and quartz. In addition, cristobalite and tridymite were apparently associated with some of the quartz grains. The inclusions were all silt size and size sorted according to specific gravity. All the inclusions showed evidence of various degrees of shock metamorphism (e.g. fracturing, droplet formation, x-ray asterism). The mineral assemblage indicates a sedimentary source material. Thus it appears that the Muong Nong-type indochinites were formed by shock melting of a well-sorted, silt-size, sedimentary material.     

MINERALOGY,PETROLOGY AND CHEMISTRY OF THE ISNA (C3) METEORITE

A total chemical analysis of the Isna, Egypt, meteorite is similar to analyses for chondrites of type C3, Ornans sub-type; however, comparison with one group of chemical data indicates that Isna is intermediate between the C3(O)'s and C3(V)'s in terms of total Fe. On the basis of atom ratios of Fe, Ca, Al, and Ti to Si, Isna can also be placed into a chemical group which includes types C1 and C2, as well as C3(O). Thin sections show a variety of small, closely-packed chondrules, fragments, and aggregate-like masses in a poorly translucent matrix. Olivine + clinoenstatite inclusions rich in metal and troilite, and olivine-rich inclusions are abundant and show evidence of shock. Ca-Al-Ti-rich inclusions, of probable high-temperature origin, contain olivine, spinel, Ca-rich nepheline, gehlenite, diopside, augite, enstatite, and anorthite. Kamacite and taenite from various occurrences in the meteorite have rather uniform Ni and Co contents, and Ni/Co for kamacite is close to that for several C3(O)'s.     

太阳黑子半影的形成和返回磁通量的来源

本文从无半影的黑子成长为带半影的黑子伴随着磁场强度增强和延伸运动这个观测事实出发，通过MHD数值模拟，证明了：（1）对流层内黑子中涡旋流动的自然形成；（2）仅在黑子表面附近磁矢才急速向外移动，最终形成我们观测到的半影磁场位形；（3）光球之上由于β迅速减少，这么小的延伸速度（0.2公里／秒）仅在β～1的光球区200公里厚的层里使磁矢有效地旋转，在约几小时至一天量级时间内将近似垂直的本影磁场向水平方向旋转，形成Osherovich所期的ReturnFlux磁位形，将注入日冕空间的本影主磁流同在色球和光球内就返回的半影磁流自然地划分开来．     

等离子体团型日冕物质抛射的形成机制

本文在球坐标二维磁静力平衡基态下，数值研究了电阻撕裂模不稳定性引起日冕电流片中发生磁场重联的过程，结果表明发生了具有两个Ｘ线的磁场重联，形成了磁岛和高温高密度的等离子体团，等离子体团在向上运动过程中有着明显的膨胀，其上升速度和膨胀过程与等离子体β值有关，这些结果可用于解释等离子体团型日冕物质抛射的形成。     

MINERALOGY,PETROLOGY AND CHEMISTRY OF LUNAR ROCK 12039

Rock 12039 belongs to the olivine-depleted group of magmatic rocks characterized by normative and modal SiO₂, absence or very low abundance of olivine, and high FeO/(FeO + MgO), Ti/Cr, and CaO/MgO ratios. Clinopyroxenes in this rock show a complex, essentially continuous, compositional zonation from augite cores through ferroaugite to ferrohedenbergite with an abrupt discontinuity at the pyroxferroite contact and, thus, are different from pyroxene in most other Apollo 12 rocks. Two grains contain thin subcalcic pigeonite zones. Texture, presence of very fine (< 1 μm) exsolution lamallae, and pyroxene zoning indicate a relatively rapid cooling history and pronounced in situ chemical fractionation. Rock 12039, on the basis of mineralogy and bulk composition, is the most highly differentiated member of the olivine-depleted basalt group     

磁场对辐射及中子星结构的影响

本文是近几年“攀登计划”执行情况的汇报。它概括了同步曲率辐射新机制发现的意义、解决的问题及应用前景。同时它阐明了中子星内部超强磁场存在的影响,以及可与观测相比较的效应。     

THE METEORITIC SHOWER OF PARAMBU,CEARA STATE,BRAZIL: — MINERALOGY AND PETROLOGY

The fall of a meteorite shower in Parambú, Ceará State, Brazil, is described. Parambú is an L-group chondrite (Urey and Craig, 1953). The mineralogical composition is olivine Fa₂₈. ortho- and clinopyroxenes, plagioclase, maskelynite, whitlockite, nickel-iron, troilite, chromite, and ilmenite. The structure of Parambú is characteristically polymict and shows an advanced brecciation. Interesting features of metamorphism are notable, with good evidence of shock.     

THE LOOP CHONDRITE: PETROLOGY,MINERAL CHEMISTRY,AND OPAQUE MINERALOGY

The Loop meteorite was found in 1962 in Gaines County, Texas, at a location very close to that where the Ashmore chondrite was found in 1969. The two specimens were assumed to be fragments of the same meteorite. The Loop meteorite is a type L6 chondrite composed of olivine (Fo_75.4Fa_24.6), orthopyroxene (En_77.6Wo_1.5Fs_20.9), clinopyroxene (En_47.5Wo_45.1Fs_7.4), plagioclase (Ab_84.3Or_5.5An_10.2), Fe-Ni metal, troilite, and chromite. Fe-Ni metal is represented by kamacite (5.8-6.4 wt % Ni, 0.88-1.00 wt % Co), taenite (30.0–52.9 wt % Ni, 0.16-0.34 wt % Co), and plessite (16.8–28.5 wt % Ni, 0.38-0.54 wt % Co). Native copper occurs as rare inclusions in Fe-Ni metal. Both chondrules and matrix have similar mineral compositions. The mineral chemistry of the Loop meteorite is quite different from that of the Ashmore, which was classified as an H5 chondrite by Bryan and Kullerud (1975). Therefore, the Ashmore and Loop meteorites are two different chondrites, even though they were recovered from the same geographic location.     

STUDIES OF BRAZILIAN METEORITES XIV. MINERALOGY,PETROLOGY, AND CHEMISTRY OF THE CONQUISTA,MINAS GERAIS,CHONDRITE

The Conquista chondrite consists of major olivine, low-Ca pyroxene (both ortho- and twinned clino-), troilite and metallic nickel-iron; minor glassy to microcrystalline material and pigeonite; and accessory chromite, high-Ca clinopyroxene and hydrous ferric oxides that formed by terrestrial weathering of metallic nickel-iron. Results of microscopic, electron microprobe, and bulk chemical studies, particularly the compositions of olivine (Fa_17.2) and low-Ca pyroxene (Fs_15.4); the contents of metallic nickel-iron (18.5%) and total iron (25.83%); and the ratios of Fe°/Fe_total (0.64), Fe°/Ni° (9.59) and Fe_total/SiO₂ (0.69) indicate H-group classification. The pronounced, well-developed chondritic texture; the slight compositional variations in constituent phases; the high Ca contents of pyroxene and the presence of pigeonite, glassy to microcrystalline interstitial material rich in alkalis and SiO₂, and of twinned low-Ca clinopyroxene suggest that Conquista is of petrologic type 4.     

日食射电观测和资料预处理

本文介绍了日食射电观测及其资料预处理的基本方法。其中包括日食观测点的选址、观测前的准备、日食观测和食后资料的预处理等。通过资料预处理 ,可得到归一化天线温度和斜率食变曲线 ,为研究日面亮度温度分布和射电源参数等基本物理量提供基本数据和资料     

拟合后剩余残差的统计检验与待估参数的选择

在空间技术的实际资料处理中,经常遇到不同待估参数组合解算的ＲＭＳ水平大致相当而估值结果相差甚远的情况．本文提出采用残差统计检验的方法,结合ＲＭＳ的大小,来判断精密定轨和参数解算的好坏．将拟合后的剩余残差序列看作一个随机变量样本,并假设其满足正态分布,采用高阶矩和皮尔逊χ２ 统计量来度量残差序列偏离正态分布的程度．根据统计检验的结果,提出选择合适的待估参数的标准