The origin of non-porphyritic pyroxene chondrules in UOCs: Liquid solar nebula condensates?

A total of 56 non-porphyritic pyroxene and pyroxene/olivine micro-objects from different unequilibrated ordinary chondrites were selected for detailed studies to test the existing formation models. Our studies imply that the non-porphyritic objects represent quickly quenched liquids with each object reflecting a very complex and unique evolutionary history. Bulk major element analyses, obtained with EMPA and ASEM, as well as bulk lithophile trace element analyses, determined by LA-ICP-MS, resulted in unfractionated (solar-like) ratios of CaO/Al₂O₃, Yb/Ce as well as Sc/Yb in many of the studied objects and mostly unfractionated refractory lithophile trace element (RLTE) abundance patterns. These features support an origin by direct condensation from a gas of solar nebula composition. Full equilibrium condensation calculations show that it is theoretically possible that pyroxene-dominated non-porphyritic chondrules with flat REE patterns could have been formed as droplet liquid condensates directly from a nebular gas strongly depleted in olivine. Thus, it is possible to have enstatite as the stable liquidus phase in a 800 × Cl dust-enriched nebular gas at a ptot of 10⁻³ atm, if about 72% of the original Mg is removed (as forsterite?) from the system. Condensation of liquids from vapor (primary liquid condensation) could be considered as a possible formation process of the pyroxene-dominated non-porphyritic objects. This process can produce a large spectrum of chemical compositions, which always have unfractionated RLTE abundances. Late stage and subsolidus metasomatic events appear to have furthered the compositional diversity of chondrules and related objects by addition of moderately volatile and volatile elements to these objects by exchange reactions with the chondritic reservoir (e.g., V, Cr, Mn, FeO as well as K and Na). The strong fractionation displayed by the volatile lithophile elements could be indicative of a variable efficiency of metasomatic processes occurring during and/or after chondrule formation. Histories of individual objects differ in detail from each other and clearly indicate individual formation and subsequent processing.     

Noble gases in metal and schreibersite of the Acuña (IIIAB) iron meteorite

Abstract— We measured abundances and isotopic compositions of noble gases in metal and schreibersite of the Acuña (IIIAB) iron meteorite. The concentrations of noble gases in Acuña metal are very low compared to those reported so far for other iron meteorites. The isotopic ratios of He, Ne and Ar indicate that they are mostly of cosmogenic origin. Cosmogenic components are even present in Kr and Xe, which could not have been produced from Fe, Ni and P and are probably due to the spallation of trace elements of higher masses. The high ⁴He/²¹Ne ratio of 420 in Acuña metal indicates that the samples were at a deep position within a very large meteoroid. The exposure ages of Acuña were estimated to be 50–200 Ma from ³He, ²¹Ne and ³⁸Ar abundances and by utilizing the diagrams of production rates vs. the ⁴He/²¹Ne ratio based on the Signer-Nier model. The low exposure age of Acuña may indicate a history different from that of other IIIAB irons whose exposure ages cluster at ～670 Ma. Otherwise, Acuña may be one of the samples with the low production rate, which can not be estimated from the diagrams of the Signer-Nier model.     

Der Weinsberger Granit im südlichen österreichischen Moldanubikum

Zusammenfassung Der Weinsberger Granit, der älieste der moldanubischen Granite Österreichs, ist ein sehr grobkörniger porphyrischer Biotitgranit mit (Volum-%) 35 bis 37% Mikroklin, 33–35% Plagioklas, 19–22% Quarz und 9–13% Biotit. Die Mikrokline sind dicktafelig nach M, erreichen eine Länge von bis zu 18 cm, fübren häufig orientierte Plagioklas- und Biotiteinschlüsse und sind stark perthitisch. Die Zusammensetzung liegt um 80 Gew. % Or, die der entmischten Kalifeldspatphase um 88% Or. Charakteristisch sind noch die hohe Triklinität und der inverse Zonarbau. Die Plagloklase sind wesentlich kleiner, sind selten primär, jedoch immer sekundär verzwillingt und zeigen einen schwachen oszillatorischen oder progressiven Zonarbau. Die durchschnittliche Zusammensetzung liegt zwischen 27 und 31% An. Die Biotite sind rothraun, stark pleochroitisch und durchweg 1 M-Polymorphe. Die Zirkone magmatischen Ursprungs sind rötlich bis undurchsichtig, zonar und sehr groß (bis zu 0·8 mm). In den Randzonen finden sich vom Nebengestein übernommene Zirkone, welche etwas kleiner und farblos sind. Das häufigste Akzessorium ist der Apatit, sehr selten findet sich Magnetit. Sehr nahe am Kontakt tritt als Verunreinigung Almandin und Muskowit auf. Auf Grund der vorliegenden Untersuchung und der im Felde von verschiedenen Autoren und vom Verfasser gemachten Beobachtungen ist die Entstehung des Weinsberger Granites auf magmatische Vorgänge zurückzuführen. Die Intrusion, die wahrscheinlich in engem Zusammenhang mit der Metamorphose des Moldanubikums stand, erfolgte unter Bedingungen, die einem p-H₂O von zinka 5000 Bar enlaprechen, also in großer Tiefe und bei relativ niedriger Temperatur.Mit 6 Textabbildungen     

A reconstruction of Quaternary pluvial environments and human occupations using stratigraphy and geochronology of fossil‐spring tufas,Kharga Oasis,Egypt

We carried out a geologic survey and a preliminary archaeological survey of four fossil‐spring tufa localities in Kharga Oasis, Egypt, to constrain the timing of pluvial episodes in the Western Desert, and to document prehistoric occupation contemporaneous with times of increased rainfall. Uranium‐series dating of the tufas confirms that at least five episodes of tufa deposition are represented in Kharga, although not every event is represented at each locality. Across the region studied, tufas were most frequently deposited as part of a fluvial barrage system, characterized by terraced, vegetated pools impounded by arcuate tufa dams and separated by small waterfalls. Available water resources during pluvial phases would have included not only spring‐fed streams but also small freshwater lakes. While Earlier Stone Age (ESA) and Middle Stone Age (MSA) lithic artifacts may be found either as surficial lags on tufas, or, less commonly, encased within tufas, Epipalaeolithic and Neolithic artifacts are generally found in or on silts within surface deflation depressions in the tufas, principally at Wadi Midauwara. © 2004 Wiley Periodicals, Inc.     

Basaltic micrometeorites from the Novaya Zemlya glacier

Abstract– A large number of micrometeorites (MMs) was recovered from glacier deposits located at the north‐eastern passive margin of the Novaya Zemlya glacier sheet. Melted, scoriaceous, and unmelted micrometeorites (UMMs) are present. Unmelted micrometeorites are dominated mostly by chondritic matter, but also a few achondritic MMs are present. Here we report the discovery of four UMMs that, according to their texture, mineralogy, and chemistry, are identified as basaltic breccias. Mineral chemistry and Fe/Mn ratios of two basaltic micrometeorites indicate a possible relationship with eucrites and/or mesosiderites, whereas two others seem to have parents, which appear not to be present in our meteorite collections. The basaltic breccia UMMs constitute 0.5% of the total population of the Novaya Zemlya MM suite. This content should be lowered to 0.25% because the Novaya Zemlya MM collection appears to be biased with carbonaceous UMMs being underrepresented.     

Buddha from space—An ancient object of art made of a Chinga iron meteorite fragment*

Abstract– The fall of meteorites has been interpreted as divine messages by multitudinous cultures since prehistoric times, and meteorites are still adored as heavenly bodies. Stony meteorites were used to carve birds and other works of art; jewelry and knifes were produced of meteoritic iron for instance by the Inuit society. We here present an approximately 10.6 kg Buddhist sculpture (the “iron man”) made of an iron meteorite, which represents a particularity in religious art and meteorite science. The specific contents of the crucial main (Fe, Ni, Co) and trace (Cr, Ga, Ge) elements indicate an ataxitic iron meteorite with high Ni contents (approximately 16 wt%) and Co (approximately 0.6 wt%) that was used to produce the artifact. In addition, the platinum group elements (PGEs), as well as the internal PGE ratios, exhibit a meteoritic signature. The geochemical data of the meteorite generally match the element values known from fragments of the Chinga ataxite (ungrouped iron) meteorite strewn field discovered in 1913. The provenance of the meteorite as well as of the piece of art strongly points to the border region of eastern Siberia and Mongolia, accordingly. The sculpture possibly portrays the Buddhist god Vai?ravana and might originate in the Bon culture of the eleventh century. However, the ethnological and art historical details of the “iron man” sculpture, as well as the timing of the sculpturing, currently remain speculative.     

Mineralogy and geochemistry of lunar meteorite Queen Alexandra Range 93069

Abstract— Queen Alexandra Range (QUE) 93069 is a glass-rich regolith breccia derived from the lunar highlands. The high abundance of glassy fragments, the presence of agglutinates, the small size of all mineral and glass fragments, the presence of mostly melt rocks, and the low abundance of pristine lunar crustal rocks, all indicate that QUE 93069 is derived from a mature regolith. This conclusion is also supported by its high siderophile element content. The most common mafic mineral is pyroxene, with compositions that indicate derivation from ferroan ANT suite rocks. Rare gabbro differentiation products may be indicated by the presence of silica, fayalitic olivine, and one pyroxferroite grain. Lithic fragments are mostly meta-melt rocks of ANT composition. The glass compositions are dominated by troctolitic anorthosite compositions, followed by gabbroic anorthosite and noritic anorthosite. Most glasses are ol-normative in composition. Some rare basic glasses of noritic composition were observed. Glass fragments and matrix glasses are alkali-poor, except for some rare alkali-rich shards. The bulk chemical composition of QUE 93069, as well as the rare-earth-element (REE) abundance pattern, is very similar to that of other highlands meteorites, such as MAC 88105 and Y-86032 and to average lunar highlands crust. One small porous clast was found to be very rich in volatile elements, as well as in most lithophile and siderophile elements. As this sample also contains abundant sulfides, the enrichments could be related to element mobilization and redistribution by volatile sulfur species.     

Trace element studies of silicate‐rich inclusions in the Guin (UNGR) and Kodaikanal (IIE) iron meteorites

Abstract— A devitrified glass inclusion from the Guin (UNGR) iron consists of cryptocrystalline feldspars, pyroxenes, and silica and is rich in SiO₂, Al₂O₃, and Na₂O. It contains a rutile grain and is in contact with a large Cl apatite. The latter is very rich in rare earth elements (REEs) (～80 × CI), which display a flat abundance pattern, except for Eu and Yb, which are underabundant. The devitrified glass is very poor in REEs (<0.1 × CI), except for Eu and Yb, which have positive abundance anomalies. Devitrified glass and Cl apatite are out of chemical equilibrium and their complementary REE patterns indicate a genesis via condensation under reducing conditions. Inclusion 1 in the Kodaikanal (IIE) iron consists of glass only, whereas inclusion 2 consists of clinopyroxene, which is partly overgrown by low‐Ca pyroxene, and apatite embedded in devitrified glass. All minerals are euhedral or have skeletal habits indicating crystallization from the liquid precursor of the glass. Pyroxenes and the apatite are rich in trace elements, indicating crystallization from a liquid that had 10–50 × CI abundances of REEs and refractory lithophile elements (RLEs). The co‐existing glass is poor in REEs (～0.1–1 × CI) and, consequently, a liquid of such chemical composition cannot have crystallized the phenocrysts. Glasses have variable chemical compositions but are rich in SiO₂, Al₂O₃, Na₂O, and K₂O as well as in HFSEs, Be, B, and Rb. The REE abundance patterns are mostly flat, except for the glass‐only inclusion, which has heavy rare earth elements (HREEs) > light rare earth elements (LREEs) and deficits in Eu and Yb—an ultrarefractory pattern. The genetic models suggested so far cannot explain what is observed and, consequently, we offer a new model for silicate inclusion formation in IIE and related irons. Nebular processes and a relationship with E meteorites (Guin) or Ca‐Al‐rich inclusions (CAIs) (Kodaikanal) are indicated. A sequence of condensation (CaS, TiN or refractory pyroxene‐rich liquids) and vapor‐solid elemental exchange can be identified that took place beginning under reducing and ending at oxidizing conditions (phosphate, rutile formation, alkali and Fe²⁺ metasomatism, metasomatic loss of REEs from glass).     

Rock 14318: A polymict lunar breccia with chondritic texture

Rock 14318 is a complex microbreccia consisting of lithic fragments, chondrules, glass spherules, and glass and mineral fragments that are embedded into a fine-grained, partly glassy matrix. Rock fragmenta, chondrules, and glasses are tightly welded to the matrix and partly recrystallized, indicating a relatively high-temperature agglomeration history. Few lithic fragments have igneous textures; most are miorobreccias that have suffered various degrees of recrystallization before they were embedded into rock 14318. Compositions of lithic fragments, glasses and chondrules, in terms of compositional rock and rock suite equivalents, represent members of the ANT (anorthositic-noritic-troctolite) suite; the alkalic high-alumina basalt (KREEP) group; high-alkali quartz basalt; basalt; and dunite. The polymict nature of many lithic fragments suggests that rook 14318 require at least two, and probably more, impact episodes for its formation. Final agglomeration took place while part of the material was hot, as is indicated by the welded texture, suggesting that the final impact event was a large one, producing a fiery cloud similar to a nuée ardente. The close similarity in texture of lunar rock 14318 to certain polymict-brecciated meteorites such as Siena suggests that meteorites of this type were also formed by complex and successive impact events on the surface of the meteorite parent body, rather than during agglomeration of the parent body.     

Human Response to Extreme Events: a review of three post-tsunami disaster case studies

Investigating survivors' behaviour prior to, during and after a disaster provides emergency management agencies with greater understanding of the complexities which influence public response. This information can then be used to develop better community-based disaster risk-reduction strategies. In this paper, we review three post-tsunami disaster case studies: the Indian Ocean tsunami (IOT) on 26 December 2004, the Java tsunami on 17 July 2006 and the South Pacific tsunami on 29 September 2009. The 2004 IOT and 2006 Java tsunami surveys involved delayed-response post-disaster research using video interviewing. The 2009 South Pacific tsunami entailed rapid-response post-disaster research using questionnaire interviews. We highlight the major outcomes of each case study and, based on these, make recommendations for improving tsunami education programs in Australia. These include educating the public about tsunami risk, natural warning signs of tsunamis and regionally specific behavioural response. To help facilitate improvements to future post-disaster research, discussion on survey-related issues from each case study is provided.