HAPPY CANYON: A NEW TYPE OF ENSTATITE ACHONDRITE

Happy Canyon [found: 1971, 34° 46.5′N, 101° 33.6′W, Texas] consists of about 85 vol. % enstatite (Fs 0.4%), 5 to 10 vol % plagioclase (An 26%), and 5 vol % diopside (Fs 0.9%). In addition, there are minor remnants of metal (Ni 6.35 wt %, Si-free) and troilite (with 5.10 wt % Cr and 1.15 wt % Ti) that have survived extensive terrestrial weathering. The meteorite has a cumulate texture, uniform-size euhedral, prismatic crystals of enstatite (0.3 to 0.4 mm long) with interstitial plagioclase, diopside, troilite, and metal. The enstatite crystals are dominantly disordered and occur in alignments that suggest flow. There are no chondrules or remnants of chondrules. The enstatite crystals contain internal negative crystal voids, which are charactieristic of enstatite achondrites, as well as internal branching submicron rivulet dislocations. The bulk composition is that of an E6 enstatite chondrite, however, it has the texture of a crystal cumulate; achondritic, but unlike that of enstatite achondrites. Glass of a granitic composition occurs mainly in the mesostasis and is compositionally like the glass found inside pyroxene crystals in the Cumberland Falls enstatite achondrite. Happy Canyon is most simply explained as an E6 composition that has melted and reprecipitated at a slightly higher oxidation state, at some depth (> 7 km), possibly in the core volume of a small, asteroidal-size parent body. In terms of classification, it occupies the gap between the recrystallized enstatite chondrites and the igneous, crystalline, unbrecciated enstatite achondrites like Shallowater. Happy Canyon is a new type of enstatite achondrite     

THE TIMMERSOI†, NIGER,HYPERSTHENE CHONDRITE

The Timmersoi meteorite, a new type L5 hypersthene chondrite from the Niger Republic is described and microprobe analyses of its olivine, orthopyroxene, clinopyroxene, plagioclase, kamacite, taenite, troilite, chromite, whitlockite, chlorapatite and limonite presented. Veins and patches of black “glassy” material are regarded as products of shock melting. In places this material contains immiscible droplets of troilite each with one or more well-formed crystals of taenite. Calculations indicate equilibrium between olivine and orthopyroxene with a temperature of equilibration of about 850 °C.     

新发现的一颗Z=1.66类星体

本文作者用北京天文台兴隆站２．１６米望远镜及卡焦ＣＣＤ摄谱仪，观测到一颗红移为１．６６的类星体，讨论了该望远镜卡焦摄谱系统的总体光效率。     

ACHONDRITE ALHA77005: ALTERATION OF CHROMITE AND OLIVINE

The olivine crystals of the 77005 achondrite are brown except for colorless shock lamellae, mottled patches, and grains adjacent to pools of impact melt. Sporadic dark alteration patches in brown olivine and Cr-rich spinel gave the following average electron-microprobe analyses: (olivine) P₂O₅ 0.9, SiO₂ 57.9, TiO₂ 0, Al₂O₃ 0.7, Cr₂O₃ 0.4, V₂O₃ 0, Fe₂O₃ (assumed oxidation state) 17.0, MgO 1.6, CaO 0.2, Na₂O 0, K₂O 1.8, SO₃ (assumed oxidation state) 9.2, Cl 0.1, sum 89.8 wt. %; (spinel) P₂O₅3.5, SiO₂2.1, TiO₂.2.2, Al₂O₃2.1, Cr₂O₃ 13.4, V₂O₃ 0.8, Fe₂O₃ 40.7, MgO 0.9, CaO 0.1, Na₂O 0, K₂O 2.0, SO₃ 11.1, Cl 0.1, sum 79.0 wt.%. Ion-microprobe analyses revealed H in both. Rare orange patches in brown olivine from another area gave SiO₂ 33–35, FeO 30-28, MgO 28–32, sum 93 wt. %. Thermal metamorphism under dry oxidizing conditions is discussed as a possible alternative to shock-induced oxidation for generation of the brown olivine (McSween and Stöffler). Because alteration patches transgress shock lamellae, and because sulfatic alteration occurs in fusion crusts of Antarctic meteorites (Gibson et al., 1983), alteration of the 77005 achondrite at the Antarctic surface is preferred to a complex series of processes needed for pre-terrestrial alteration.     

TIERRA BLANCA: AN UNUSUAL ACHONDRITE FROM WEST TEXAS

Tierra Blanca is an achondrite (sensu stricto) composed chiefly of orthopyroxene, olivine, plagioclase and clinopyroxene. The mineralogy, major element chemistry and texture are similar to Winona and also Mt. Morris, Acapulco and Antarctic meteorite ALHA 77081 to some degree. The designation of this group as “Winonaites,” as suggested by Prinz et al. (1980), seems justified and useful.     

自由波核章动的光学和新技术检测

本文应用当今最高精度的经典仪器光学观测资料、新技术的综合观测资料和单一的ＶＬＢＩ观测资料检测了自由液核章动，得到其周期为４１５—４１８天，分析了其运动形态为逆向的圆周运动，并计算了其振幅为亚毫秒级．     

GDJ目视经纬仪光电改装后的观测方法

本文主要介绍GDJ打印经纬仪经光电改装后的系统特点及新的观测方法,并由此而获取的效益。     

Metal/sulfide–silicate intergrowth textures in EL3 meteorites: Origin by impact melting on the EL parent body

Abstract– We document the petrographic setting and textures of Fe,Ni metal, the mineralogy of metallic assemblages, and the modal mineral abundances in the EL3 meteorites Asuka (A‐) 881314, A‐882067, Allan Hills 85119, Elephant Moraine (EET) 90299/EET 90992, LaPaz Icefield 03930, MacAlpine Hills (MAC) 02635, MAC 02837/MAC 02839, MAC 88136, Northwest Africa (NWA) 3132, Pecora Escarpment 91020, Queen Alexandra Range (QUE) 93351/QUE 94321, QUE 94594, and higher petrologic type ELs Dar al Gani 1031 (EL4), Sayh al Uhaymir 188 (EL4), MAC 02747 (EL4), QUE 94368 (EL4), and NWA 1222 (EL5). Large metal assemblages (often containing schreibersite and graphite) only occur outside chondrules and are usually intergrown with silicate minerals (euhedral to subhedral enstatite, silica, and feldspar). Sulfides (troilite, daubréelite, and keilite) are also sometimes intergrown with silicates. Numerous authors have shown that metal in enstatite chondrites that are interpreted to have been impact melted contains euhedral crystals of enstatite. We argue that the metal/sulfide–silicate intergrowths in the ELs we studied were also formed during impact melting and that metal in EL3s thus does not retain primitive (i.e., nebular) textures. Likewise, the EL4s are also impact‐melt breccias. Modal abundances of metal in the EL3s and EL4s range from approximately 7 to 30 wt%. These abundances overlap or exceed those of EL6s, and this is consistent either with pre‐existing heterogeneity in the parent body or with redistribution of metal during impact processes.     

THE MILLS,NEW MEXICO,CHONDRITE — A NEW FIND

A mineralogical and chemical analysis has been performed on a slice of the Mills, New Mexico, chondrite, which was found in August 1970. The mineralogical composition is olivine Fa_19.5, bronzite, Fs_17.4, plagioclase, nickel-iron, troilite and ilmenite. The chemical analysis confirms that Mills is a typical bronzite, H5 chondrite, with considerable degree of weathering, as indicated by the presence of large amounts of Fe₂O₃. A comparison with other stones found in the same New Mexico region by Nininger may show a possible relation between Mills and previous finds.     

USTÍ NAD ORLICI: A NEW L6 CHONDRITE FROM CZECHOSLOVAKIA

Ustí nad Orlici (Kerhartice), a meteorite which fell on June 12, 1963 in Czechoslovakia, is classified as a L6 chondrite. Compositions of olivine (Fa 23.4), orthopyroxene (Fs 20, Wo 1.3), plagioclase (Ab₈₅An₁₀Or₅) along with the bulk composition of the meteorite support this classification. Chromite compositions vary with grain size. Large chromites are higher in TiO₂ and lower in Fe³ than small chromites. This may indicate that either these two chromites formed initially under different fO₂ conditions, or that this difference resulted from different equilibration behaviors of both chromites as a function of grain size. The meteorite contains three distinct sulfide assemblages: 1) troilite-pentlandite, 2) troilite, pentlandite-cubanite-chalcopyrite-pyrrhotite-mackinawite, 3) troilite-tetrataenite-(Fe, Cu, Ni)_{1***. 02}S. These assemblages indicate equilibration down to temperatures close to 200 °C.     

CILIMUS: A NEW CHONDRITE FALL

Cilimus is a new Indonesian chondrite. Its mineralogy and chemistry categorize it as a veined, intermediate-to-white hypersthene or L-5 chondrite. Black veins and impact-produced glasses including maskelynite show evidence that Cilimus has been severely shocked.     

新状态方程下中子星的性质

利用扩展的Skyrme作用可从Hartree-Fock多体理论中给出一种新的状态方程。本文在这个状态方程的基础上研究了静态中子星的性质。对于SKM和SG2这两个较好的Skyrme相互作用模型计算得到中子星的最大质量分别为Mmax=1.7M。，Max=1.67M。，此外，本文还研究了中子星的其它性质，如引力红移、惯量矩等，计算结果与观测以及Glitch模型符合。最后还发现在这种状态方程下，中子星冷却仅能通过冷却速度相对较慢的修正的Urca过程来实现。为便于比较，文中还计算了AV14＋TBF和Paris TBF这两种三体相互作用模型下的中子星的性质。     

A comparative study of opaque phases in Qingzhen (EH3) and MacAlpine Hills 88136 (EL3): Representatives of EH and EL parent bodies

Abstract— Opaque minerals in the Qingzhen (EH3) and MacAlpine Hills (MAC) 88136 (EL3) enstatite chondrites were studied and compared with other EH and EL chondrites. All opaque minerals usually occur in multi‐sulfide‐metal clasts and nodules in the matrix between chondrules (El Goresy et al., 1988). The higher abundance of opaque minerals, the occurrence of niningerite and various alkali‐sulfides (e.g., caswellsilverite, phases A and B, djerfisherite) are diagnostic criteria for EH chondrites, while alabandite is characteristic for EL chondrites. In addition, EH chondrites are characterized by enrichments of Si in both kamacite and perryite, and alkali elements in sphalerite and chalcopyrite. The Mn contents of daubreelite and sphalerite are lower in EH than in EL chondrites. These are consistent with lower oxygen fugacity and higher H₂S fugacity of EH than EL chondrites. In contrast, the discovery of sphalerite and Zn‐rich daubreelite in MAC 88136 indicates that their absence in EL6 chondrites is probably related to thermal metamorphism in the parent body. Schreibersite microspherules are commonly enclosed in most sulfides in Qingzhen, but are absent in MAC 88136. They were once molten, and probably predated all sulfide host phases. The petrographic setting and chemical compositions of the sulfide hosts of the schreibersite microspherules in EH3 chondrites are consistent with formation by condensation. The earliest sulfide condensates oldhamite and niningerite occupy the interiors of the clasts and nodules, whereas the rims consist of troilite and djerfisherite. In addition, in Qingzhen, some other troilite, djerfisherite and sphalerite assemblages coexist with perryite. They were produced by sulfurization of metallic Fe‐Ni in the nebula. In MAC 88136, sulfurization of Si‐bearing Fe‐Ni metal is less pronounced, and it produced troilite, schreibersite and less abundant perryite. Two kinds of normal zoning and a reverse zoning trends of niningerite, and both normal and reverse zoning of sphalerite were found in clasts and nodules in Qingzhen. The coexistence of normal and reverse zoning profiles in niningerite grains in the same meteorite strongly suggests that they formed before accretion in the parent body, because an asteroidal metamorphic or an impact event in the parent body would have erased these contrasting profiles and destroyed the textural settings. In contrast, alabandite in MAC 88136 shows only normal zoning, with the FeS content decreasing to 9.3 mol% toward troilite, indicating very slow cooling at low temperature.     

FLUX EMERGENCE AND PROMINENCES: A NEW SCENARIO FOR 3-DIMENSIONAL FIELD GEOMETRY BASED ON OBSERVATIONS WITH THE ADVANCED STOKES POLARIMETER

This paper presents an interpretation of the evolution of the vector magnetic field at the photosphere based on measurements of the advanced Stokes polarimeter, along with chromospheric H from the Lockheed instrument operating on La Palma and X-ray images of the corona from Yohkoh. These measurements are consistent with the emergence of a nearly closed magnetic structure from the solar interior into the corona. The highly non-potential field topology inferred from the data suggests that strong field-aligned currents exist in the emergent magnetic structure as it buoyantly rises through the photosphere. Material trapped in this closed structure is pulled upward to later condense into a prominence. By analogy of this small active region evolution with the observed properties of large quiescent prominences, we speculate that this process might also be operative on a much larger scale. A 3-dimensional magnetostatic model is presented which has many topological features in common with the observations.     

Equilibration temperatures of EL chondrites: A major downward revision in the ferrosilite contents of enstatite

Abstract A study of enstatite grains separated from EL6 chondrites shows ferrosilite contents to be ～0.02–0.04 mol%, about an order of magnitude lower than reported in the literature. The higher values reported earlier can probably be attributed to the excitation of Fe atoms in Fe-Ni and FeS, in part from μm-sized blebs of FeS and Fe-Ni commonly present in enstatite grains but mainly from large neighboring opaque grains excited by bremsstrahlung or by doubly backscattered electrons. Our EL6 ferrosilite contents are similar to those observed in coarse enstatite grains in some aubrites. The equilibrium between ferrosilite and Si-bearing kamacite is highly temperature dependent. At constant Si concentration in kamacite, the equilibrium ferrosilite mole fraction drops by a factor of roughly 2.5 for each 100 K decrease in the equilibrium temperature. As a result, the compositions of these two most common EL6 phases can be used to estimate metamorphic equilibration temperatures. The inferred temperatures are near 1200 K.     

RICA AVENTURA: A NEW IRON METEORITE FROM CHILE

Rica Aventura, a group IVA fine octahedrite, was found in 1910 near the now abandoned village of Rica Aventura, Chile (69° 37′W, 21° 59′S). Based on chemical evidence it appears to be a unique new find.     

THE NARAGH METEORITE: A NEW OLIVINE-BRONZITE CHONDRITE FALL

At 9:20 A.M. on August 18, 1974, a stony meteorite of approximately 3200 grams struck the roof of a secondary school at Naragh, Central Iran, (51°30′E, 33°45′N). The ellipsoidal dark-gray meteorite was 17 × 15 × 13 cm (density 3.62 gr/cm³). XRF and wet chemical analysis yields the bulk composition of the meteorite as follows in weight percent: Fe 11.95, Ni 1.05, Co 0.07, FeS 5.49, SiO₂ 37.15, TiO₂ 0.15, Al₂O₃ 2.43, Cr₂O₃0.62, FeO 14.25, MnO 0.23, MgO 23.79, CaO 1.61, Na₂O 0.92, K₂O 0.08, P₂O₅ 0.26. Modal mineral contents (in volume percent) are olivine 40, orthopyroxene 25, clinopyroxene 3, plagioclase 10.5, chromite 0.80, phosphate 0.70, troilite 6, metal phases 14. The meteorite is fine-grained, with average grain size about 0.4–0.6 mm and contains numerous recrystallized glassy chondrules. Olivine occurs as laths and radiating crystals in chondrules and as coarse-grained phenocrysts and interstitial microcrystalline grains in the matrix. These olivines have relatively uniform composition (Fo_80–82Fa_20–18). Fine-grained skeletal orthopyroxenes of average composition (En₁₆Fs₈₂Wo₀₁) are inter-grown with olivine in both chondrules and matrix. Clinopyroxene and plagioclase of average composition (En_6.5Fs₄₈Wo_45.5) and (Ab₈₂An₁₂Or₀₆) respectively, are evenly distributed in the matrix, together with kamacite (Fe_92–95), plessite (Fe_69.6–82.2) and taenite (Fe_46.7–66.1), troilite (Ni-free) and chromite grains. The high ratios of total Fe to SiO₂ of 0.71, metallic Fe to total Fe of 0.54, and SiO₂ to MgO of 1.56 in the bulk composition, the Fa component of olivine grains of 17.5–19.6, and the high Ca content of orthopyroxenes between 0.53 and 0.87 wt % suggest that the Naragh meteorite belongs to the H-group and petrologic type 6 of Van Schmus and Wood (1967) classification. In addition, the occurrence of fine-grained clear sodic plagioclase, the presence of numerous recrystallized chondrules with homogeneous silicate minerals, and the absence of Ni in the sulfide phase indicate that the Naragh meteorite has been metamorphosed after the initial crystallization in the parental body.     

THE TOULON METEORITE: A NEW CHONDRITE FROM ILLINOIS

Toulon is an olivine-bronzite chondrite found near Toulon, Illinois in 1962. It contains abundant, well preserved chondrules, as well as glasses that are not well devitrified. Most of the metal has been weathered out. Olivine and pyroxene are well equilibrated. We have classified it as an H5 chondrite.     

THE IJOPEGA CHONDRITE: A NEW H6 FALL

The Ijopega (Papua New Guinea) meteorite is a new H6 group chondrite fall which contains olivine (Fa 19.9 mole %), bronzite (Fs 17.8 mole %), plagioclase (An 12.1 Or 6.3 Ab 81.6 mole %), diopside, kamacite, taenite, troilite, chromite and whitlockite. The meteorite is extensively recrystallized and brecciated, and shows evidence of moderate shock deformation. Examination of Fe²⁺ and Mg partitioning between ortho- and clinopyroxene indicates a high equilibration temperature (940° or 880 °C). Chemical analysis shows the meteorite to be rich in S, containing about twice the average H-group abundance. Trace elements, including REE, are in accord with established H-group chondrite abundances.