摘要:

The Hedjaz meteorite has been studied in detail and on a chemical basis, with 22.1% total Fe, 9% metallic Fe, 1.3% Ni and constant olivine composition (Fa23–24), can be classified as an L‐group chondrite. However, petrographically Hedjaz is quite hoterogeneous and contains features characteristic of types 3, 4, 5, and 6, observations that refute a petrographic type classification. Indeed, Hedjaz, as a complex breccia, exhibits no evidence of metamorphic equilibration after accretion and supports the contention that type 4 (also 5 and 6) chondrites are not derivatives of type 3 material, and that types 5 and 6 are not necessarily more “metamorphosed,” only better cryst

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1986.tb01238.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1986.tb01239.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1986.tb01240.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1986.tb01241.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

The comparison of the Tunguska body explosion with the effect of terminal flares of meteors and fireballs leads us to the conclusion that these events are of a similar nature but differ only by their scale. We consider that the dynamics of progressive breaking and evaporation of meteoric bodies during their entry into the terrestrial atmosphere could explain the terminal burst. An extremely porous body model for the Tunguska meteorite was analysed and rejected as unsatisfactory. The realistic values of the initial velocity (∼30 km/sec) and of the inclination angle for the Tunguska's trajectory (5–15°) give orbital elements not in contradiction with the cometary origin of the Tunguska

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1986.tb01242.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

The Ragland, New Mexico chondrite was found in 1978, and consists of a single stone of 12.16 kg that broke into three pieces. The stone is moderately weathered and has a pronounced chondritic texture. Bulk composition favors an LL classification, and modal analysis and oxygen isotopic composition are consistent with this. The thermoluminescence sensitivity of 0.056 ± 0.020 normalized to Dhajala, compositional variability of olivine (mean Fa 18.3, σ = 10.1) and low‐Ca pyroxene (mean Fs 14.6, σ = 6.7), and Ca concentrations in olivine indicate metamorphic subtype 3.4 ± 0.1. The isotopically heavy oxygen composition, which is characteristic of subtypes 3.0–3.1, may be a primary characteristic and not a result of weathering. Low concentrations of radiogenic40Ar and planetary36Ar suggest noble g

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1986.tb01243.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1986.tb01244.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1986.tb01245.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1986.tb01246.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1986.tb01237.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY