摘要:

Spherical translucent green glasses found in New Guinea for many years have the external appearance of stream abraded tektites, but are chemically distinct from known tektite groups. Their chemical composition is most similar to artificial glasses. If these objects are the source of reports of tektites occurring in New Guinea, the existence of New Guinea tektites must now be discounted.

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1980.tb00522.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Petrographic measures of disequilibrium in the ALHA 77278 chondrite indicate that this meteorite is more equilibrated than its exceptionally high volatile element contents suggest. Based on its metal compositions, this meteorite should be classified as an LL3 rather than an L3 chondrite.

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1980.tb00523.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

The Gomez meteorite, weighing slightly over 47 kg, was found near the town of Gomez, Terry County, Texas (33° 10′53 “N, 102° 24′5” W) prior to 1974. It is a highly weathered, equilibrated L‐6 chondrite of composition Fa 26, Fs 23. A large number of chromite grains and possibly partially weathered lawrencite grains

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1980.tb00524.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

The mineralogical and chemical compositions of meteorites from the Motta di Conti, Vercelli, Italy, shower (February 29, 1868) have been determined. Microprobe analyses, of olivine (Fa19,6) and orthopyroxene (Fs17,8), as well as the bulk chemical composition, particularly the ratios of SiO2/MgO (1.50), Fe°/Ni° (11.03), Fetotal/SiO2(0.81), Fe°/Fetotal(0.70) and the content of Fetotal(28.60%) classify the meteorite as an H‐group chondrite. The percentage of total metallic nickel‐iron (22.06%) is somewhat higher than the average in H‐group chondrites. The texture of our stone shows evidence of metamorphism. The integration between matrix and chondrules is advanced and may suggest a high petrographic grade, but the identification of several microscopic features (e.g. small grains of monoclinic twinned pyroxene, FeNi‐FeS intergrowths, globules and mosaic) leads to the conclusion that a variety of petrographic types (4–6) are present. Metamorphic equilibration in chondrites is discussed and a preliminary hypothesis for H4–6 chondrite

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1980.tb00525.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Two meteoritic stones weighing roughly 600 and 200 g fell on 14 April 1942 near Parsa, Bihar, India. The meteorite is a high‐Fe (EH) enstatite chondrite on the basis of its large abundance of chondrules, its low concentrations of refractory elements, the Si content of its metal (25–30 mg/g), and its enstatite composition Mg0.975Ca0.007Fe0.018. The high contents of Zn, Cd and In suggest that Parsa is petrologic type 4. A unique feature is an irregular nodule of coarse enstatite, several cm long which is chemically different in its Ca and Fe content compared to the matrix. We have increased the elemental concentrations by 10% to allow for terrestrial oxidation and hydration. The revised siderophile and moderately volatile element concentrations fall within the range observed in EH chondrites and mostly outside the range found in EL chondrites. Terrestrial alteration is indicated by the presence of limonite and other hydrated minerals as well as the morphologies revealed by scanning electron microscopy. The26Al activity is 51 ± 6 dpm/kg consistent with the calculated production rate. Cosmogenic track densities combined with the21Ne,38Ar exposure age of 17 Myr indicate 4–10 cm ablation loss, or a preatmospheric mass of about

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1980.tb00526.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1980.tb00527.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1980.tb00528.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1980.tb00529.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1980.tb00530.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1980.tb00531.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY