The Gove relict iron meteorite from Arnhem Land,Northern Territory,Australia

On February 24, 1979, a deeply oxidized mass of iron meteorite was excavated from bauxite at an open cut mine on the Gove Peninsula, Northern Territory, Australia. The meteorite, measuring 0.75–1 m in diameter and of unknown total weight, was found at coordinates 12°15.8′S, 136°50.3′E. On removal from the ground, the meteorite is reported to have disintegrated rapidly. A preliminary analysis at the mine laboratory reportedly gave 8.5 wt% Ni. A modern analysis of oxidized material gave Ni = 32.9, Co = 3.67 (both mg g^?1), Cr = 168, Cu = 195, Ga = 22.5, Ge = <70, As = 4.16, W = 1.35, Ir = 10.5, Pt = 21.2, Au = 0.672 (all μg g^?1), Sb = <150, and Re = 844 (both ng g^?1). Competent fragments of oxidized material retain a fine to medium Widmanstätten pattern with an apparent average bandwidth of 0.5 mm (range 0.2–0.9 mm in plane section). Primary mineralogy includes rare γ–taenite and daubréelite, and secondary minerals produced by weathering include awaruite (with up to 78.5 wt% Ni) and an, as yet, unnamed Cu‐Cr‐bearing sulfide with the ideal formula CuCrS₂ that is hitherto unknown in nature. Deep weathering has masked many of the features of the meteorite; however, the analysis normalized to the analyses of fresh iron meteorites favors chemical group IIIAB. The terrestrial age of the meteorite is unknown, although it is likely to be in the Neogene (2.5–23 Ma), which is widely accepted as the major period of bauxite formation in the Northern Territory of Australia. Gove is the second authenticated relict meteorite found in Australia.     

The Foelsche structure,Northern Territory,Australia: An impact crater of probable Neoproterozoic age

Abstract— The Foelsche structure is situated in the McArthur Basin of northern Australia (16°40′ S, 136°47′ E). It comprises a roughly circular outcrop of flat‐lying Neoproterozoic Bukalara Sandstone, overlying and partly rimmed by tangentially striking, discontinuous outcrops of dipping, fractured and brecciated Mesoproterozoic Limmen Sandstone. The outcrop expression coincides with a prominent circular aeromagnetic anomaly, which can be explained in terms of the local disruption and removal or displacement of a regional mafic igneous layer within a circular area at depth. Samples of red, lithic, pebbly sandstone from the stratigraphically lowest exposed levels of the Bukalara Sandstone within the Foelsche structure contain detrital quartz grains displaying mosaicism, planar fractures (PFs) and planar deformation features (PDFs). PFs and PDFs occur in multiple intersecting sets with orientations consistent with a shock metamorphic origin. The abundance and angular nature of the shocked grains indicates a nearby provenance. Surface expression and geophysical data are consistent with a partly buried complex impact crater of ?6 km in diameter with an obscured central uplift ?2 km in diameter. The deformed outcrops of Limmen Sandstone are interpreted as relics of the original crater rim, but the central region of the crater, from which the shocked grains were likely derived, remains buried. From the best available age constraints the Foelsche structure is most likely of Neoproterozoic age.     

Nullarbor 018: A new L6 chondrite from Australia

Abstract— A new meteorite find from the Nullarbor Plain in Australia was studied using optical, SEM, and electron microprobe techniques. The meteorite, Nullarbor 018, is an orthodox L6 chondrite that experienced minor-to-moderate alteration of metal during terrestrial weathering (grade A–B to B). During weathering, troilite was preferentially altered, and roughly 20% of the original complement of S in the meteorite was removed. Shock metamorphic effects corresponding to shock stage S4 (or shock facies d) are found, including the presence of some diaplectic feldspar (maskelynite). The meteorite is not obviously paired with other finds from the Nullarbor region, but the possibility that it is paired cannot be excluded.     

A survey of Saturn''s Northern Hemisphere from 1979 to 1987

A photographic survey in four spectral regions (ultraviolet, blue, visible and red) of the Northern Hemisphere of Saturn's atmosphere, has been carried out between 1980 (epoch of the edgewise apparition of the rings) and 1987 (ring's maximum aperture), with the aim of analyzing the changes in the cloud morphology and reflectivity with respect to the spacecraft aspects in 1979 (Pioneer 11) and 1980–1981 (Voyager 1 and 2). Very few variations were detected in the meridional position of the belts and zones ; only a shift of 4000 km toward the North appeared to occur in 1984 in ultraviolet light to the region at latitude 46°N (occupied in 1980–1981 by the “ribbon” feature). Other belts and zones remained stable to ground-based telescopic resolution during the whole period. An increase of 7% in the reflectivity ratio of the belt NEB and the zone EZ, was noted in the spectral interval from 4000 to 6500 Å last year. This can be attributed to the seasonal insolation variation.     

Denman 002: A new CV3 chondrite from South Australia

Abstract— Denman 002 is a new Australian carbonaceous chondrite. A single stone of 30 g was recovered in 1991 May near Fisher Station on the Trans Australian Railway, Nullarbor Plain, South Australia (30°36′S, 130°04′E). Texture, mineral and chemical composition indicate that it is a CV3 chondrite of oxidised subgroup with several similarities to Allende. It is composed of sharply defined chondrules, Ca-Al rich inclusions up to 3.5 mm across, olivine aggregates and fine-grained, nearly opaque matrix (40 vol%). Silicates are compositionally highly heterogeneous (olivine Fa: 0.2–45.6 mol%, PMD: 109.7). Denman 002 shows shock effects of stage SI and weathering of category A.     

The Loxton meteorite: A new olivine-bronzite chondrite from South Australia

Abstract— The Loxton meteorite is a single stone of 22 g found in South Australia in 1968. It has been classified as an L5 chondrite, shock facies ‘a,’ and contains olivine (Fa₂₄), orthopyroxene (Fs_21–22), clinopyroxene (Wo_44.7En_45.9Fs_9.4), nickel-iron, troilite, chromite and chlorapatite.     

A catalogue of RR Lyrae stars from the Northern Sky Variability Survey

A search for RR Lyrae stars has been conducted in the publicly available data of the Northern Sky Variability Survey. Candidates have been selected by the statistical properties of their variation; the standard deviation, skewness and kurtosis with appropriate limits determined from a sample 314 known RRab and RRc stars listed in the General Catalogue of Variable Stars. From the period analysis and light-curve shape of over 3000 candidates 785 RR Lyrae have been identified of which 188 are previously unknown. The light curves were examined for the Blazhko effect and several new stars showing this were found. Six double-mode RR Lyrae stars were also found of which two are new discoveries. Some previously known variables have been reclassified as RR Lyrae stars and similarly some RR Lyrae stars have been found to be other types of variable, or not variable at all.     

The Binningup H5 Chondrite: A New Fall from Western Australia

Abstract— Following a brilliant daylight fireball at 10:10 a.m. (local time) on 30 September 1984, a single stone weighing 488.1 grams was recovered from Binningup beach (33°09′23″S, 115°40′35″E), Western Australia. Data from 23 reported sightings of the fireball indicate an angle of trajectory 20–40° from the horizontal, a flight-path bearing N210°E and an end-point (ca. 32°39′S, 115°54.5′E) at a height of ～20–30 km. A recrystallized chondritic texture and the presence of olivine and low-Ca orthopyroxene with compositions of Fa_18.4 (PMD 1.1)and Fs_16.1 (PMD 1.1), respectively, show that Binningup is a typical member of the H-group of ordinary chondrites. Uniform mineral compositions and the presence of generally microcrystalline plagioclase feldspar indicate that the meteorite belongs to petrologic type 5. Pervasive fracturing of silicates suggests mild pre-terrestrial shock loading. Measurements (dpm kg^?1) of cosmogenic radionuclides including ²²Na (61 ± 5), ²⁶Al (49 ± 3) and ⁵⁴Mn (66 ± 10) indicate a normal history of irradiation.     

New Chilean iron meteorites: Medium octahedrites from Northern Chile are unique

Abstract— We report data on three new iron meteorites from Northern Chile and propose names. All are unnamed iron meteorites from the meteorite collection at the Universidad de La Serena. For two, the provenance is unknown; for the third, the presumed discovery site is in the countryside east of Iquique. The three meteorites have been analyzed by instrumental neutron activation analysis (INAA) and their structures examined with a binocular microscope. La Serena is a complete 663 g iron, a new member of group IIICD; it is not paired with any other iron. Elqui has a mass of 260 g; two faces are fractures, possibly produced by human actions, but fusion crust appears to be present on some of the remaining surface. It is a hexahedrite and a member of group IIAB, but its composition differs from that of all other Chilean hexahedrites. The third iron, Pozo Almonte, is a medium octahedrite member of group IIIAB, one of the most common meteorite groups. To find out whether it is paired, we assembled a full set of IIIAB iron meteorites from Northern Chile. Our compositional data show that Pozo Almonte is not paired with any other IIIAB iron, and that there are no pairings within the full set with the possible exception of Joel's Iron and Sierra Sandon, which differ only in their contents of Ir, 0.39 and 0.34 μg/g, respectively. However, Buchwald's (1975) structural observations rule out this possible pairing. We find appreciable differences in Cu, As and Au between the previously paired IIIAB irons Chañaral and Ilimaës and conclude that these should not be paired.     

Structures of Well Preserved Australite Buttons from Port Campbell,Victoria, Australia

Abstract. Complete and nearly complete australite buttons in good states of preservation from Port Campbell, Victoria, show excellent structural details and are of great scientific importance. Some of the features on their posterior surfaces are doubtfully assigned a primary origin in an extraterrestrial birthplace but have been modified by terrestrial solution-etching. Secondary features on their anterior surfaces are due to the effects of aerodynamic frictional heating during transit with stable orientation at supersonic velocity through the earth's atmosphere. Tertiary processes such as subaerial weathering have played some part in slightly modifying their shape and sculpture patterns. They contrast strongly with the many thousands of australites collected from the arid and sub-arid regions of Australia, and with a considerable number that were abraded by stream or gravity transportation in the more temperate zones of the strewnfield. The majority of such specimens have been more severely weathered with the resultant loss of much or all of their primary and secondary features.     

Petrology and microstructure of distal impact ejecta from the Flinders Ranges,Australia

Abstract— The Acraman impact ejecta from Bunyeroo Gorge in the central Flinders Ranges consist of clast-bearing and sandy sublayers set in a shale host rock. A calculated transient crater diameter for the Acraman impact of at least 34 km was obtained from average thicknesses and estimated distances of the ejecta from the impact in the Gawler Ranges. The ejecta contain numerous grains of quartz and zircon that display impact-produced features, including one or more sets of decorated planar deformation features. There is also much unshocked material incorporated in the ejecta layer. The coarse-grained ejecta layer embedded within fine-grained sediments allowed easy passage for diagenetic fluids that produced a porous honeycomb structure in the clays and enhanced the content of elements such as Cu, Pb, Zn, and U. The clay fraction of the ejecta layers consists of vermiculite and kaolinite, probably formed from alteration and weathering of glassy components. It appears that quartz and zircon grains are the only remnants unaltered by diagenetic processes.     

Tabbita: An L6c chondrite from New South Wales,Australia

Abstract— A crusted stone weighing 3.10 kg was found in 1983 near Tabbita in south central New South Wales (ca. 34°03′S, 145°50′E), Australia. Compositions of the ferro-magnesian silicates (olivine Fa_24.6; orthopyroxene Fs_20.9) show that the meteorite belongs to the L-group of chondrites. Uniformity of silicate compositions and the presence of abundant crystalline plagioclase feldspar (An_10.8Ab_81.7Or_7.5) show that the meteorite belongs to petrologic type 6. Silicates that display undulose extinction, and the absence of any thermal effects induced by shock indicate that Tabbita is shock facies c. Tabbita is distinct from several other L6 chondrites found in the same general area.     

The Yarle Lakes 001 meteorite: A H5 chondrite from South Australia

Abstract— The Yarle Lakes 001 meteorite was a single stone of 913 g found approximately 20 km north of Watson, South Australia, in 1990 October. It consists of olivine (Fa_{18.7 ± 0.4}, n = 30), low-Ca pyroxene (Fs_{16.6 ± 0.2} Wo _{12 + 0.4}, n = 15). feldspar, high-Ca pyroxene, metallic Fe-Ni and troilite. Based on texture and mineral chemistry, Yarle Lakes 001 is classified as a H5 chondrite of shock stage S3.     

Lake Machattie,a weathered H5 chondrite find from Queensland,Australia

Abstract— Lake Machattie is an H5a chondrite find. The 2.6-kg stone is heavily weathered; unoxidized metal occurs only as 10-μm-size blebs enclosed in olivine.     

Element composition of dust from a shallow Dunde ice core, Northern China

The Dunde ice cap (38°06'N, 96°24'E, with a summit of 5325 m) is situated at the centre of the northern Chinese deserts and receives dust from these regions. Here, we present the trace and rare earth element (REE) compositions of dust extracted from a shallow ice core from the Dunde ice cap, which provide a framework to trace the source of Dunde dust. Trace and REE parameters of Dunde dust show characteristics of a typical eolian deposit, with an average La/Th ratio of 2.6, a Th/U ratio of 3.7, and a strong negative Eu anomaly (0.61). The dirty layers in the ice core section have the same element characteristics as in the clear layers, indicating that the dust in Dunde is well-mixed and has a stable composition. Trace element and REE ratio plots show that Dunde dust has a similar composition to the finer fraction materials in the Taklimakan desert, suggesting that the Tarim Basin might be an important source for Dunde dust under the present circulation, but not favoring a material contribution from Badain Jaran. Our results reveal distinct differences in composition between Dunde dust and Chinese loess materials, which suggests that they have different sources.     

Characterization and significance of shocked quartz from the Woodleigh mpact structure,Western Australia

Abstract— We re‐examined the buried Woodleigh structure in Western Australia, which has been inferred to be a multi‐ringed, 120 km diameter impact crater, because the proposed size and possible synchronicity with one of the pre‐Mesozoic mass extinction events has attracted controversy. We undertook a detailed study of the petrology and mineralogy of a number of samples of core from the Woodleigh‐1 borehole that was drilled into the central uplift of the structure. Crystalline Proterozoic basement rocks comprising granites and gneisses in the Woodleigh‐1 core contain minor brecciation in discrete veins and reveal clear evidence of shock metamorphism over the full extent of the core. Imaging of laboratory‐etched quartz showed that a large number of grains contain shock deformation lamellae. Microstructural and crystallographic analysis of these lamellae by TEM showed that they are planar deformation features (PDFs) that have subsequently undergone annealing and water assisted recrystallization. The available geological, petrographic, and mineralogical evidence suggest that Woodleigh is an eroded impact crater that is nearer to 60 km than 120 km in diameter. Future drilling projects should better constrain the level of erosion, and may reveal any preserved impact lithologies.     

Geochemistry of Darwin glass and target rocks from Darwin crater,Tasmania, Australia

Abstract— Darwin glass formed about 800,000 years ago in western Tasmania, Australia. Target rocks at Darwin crater are quartzites and slates (Siluro‐Devonian, Eldon Group). Analyses show 2 groups of glass, Average group 1 is composed of: SiO₂ (85%), Al₂O₃ (7.3%), TiO₂ (0.05%), FeO (2.2%), MgO (0.9%), and K₂O (1.8%). Group 2 has lower average SiO₂ (81.1%) and higher average Al₂O₃ (8.2%). Group 2 is enriched in FeO (+1.5%), MgO (+1.3%) and Ni, Co, and Cr. Average Ni (416 ppm), Co (31 ppm), and Cr (162 ppm) in group 2 are beyond the range of sedimentary rocks. Glass and target rocks have concordant REE patterns (La/Lu = 5.9–10; Eu/Eu* = 0.55–0.65) and overlapping trace element abundances. 87Sr/⁸⁶Sr ratios for the glasses (0.80778–0.81605) fall in the range (0.76481–1.1212) defined by the rock samples. ε‐Nd results range from –13.57 to –15.86. Nd model ages range from 1.2–1.9 Ga (CHUR) and the glasses (1.2–1.5 Ga) fall within the range defined by the target samples. The ⁸⁷Sr/⁸⁶Sr versus 8⁷Rb/⁸6Sr regression age (411 ± 42 Ma) and initial ratio (0.725 ± 0.016), and the initial ⁴³Nd/144Nd ratio (0.51153 ± 000011) and regression age (451 ± 140 Ma) indicate that the glasses have an inherited isotopic signal from the target rocks at Darwin crater. Mixing models using target rock compositions successfully model the glass for all elementsexcept FeO, MgO, Ni, Co, and Cr in group 2. Mixing models using terrestrial ultramafic rocks fail to match the glass compositions and these enrichments may be related to the projectile.