摘要:

An ordinary chondrite weighing 472 g kept in the Shinto shrine, Suga Jinja, Nogata‐shi, Fukuoka‐ken, Japan, as treasure, was said to have fallen in the precinct of the shrine, approximately 130°45.0′E. and 33°43.5′N., on May 19, 861 A.D. The date of fall was confirmed by old literature, as well as written script on, and14C age determination of, the lid of the wooden box in which it has been stored.The chondrite was named Nogata after the present name of the place of fall.Although the Fe content of Nogata is a little too low, the bulk chemical composition, comparison of the norm with average H‐, L‐ and LL‐group chondrites, the relation of Femetal/Ni versus Femetal/Fetotal, and molar composition of olivine and orthopyroxene indicate that Nogata is an L‐group chondrite.From the well recrystallized structure, extreme obliteration of the primary chondrule texture, homogeneous composition of olivine and orthopyroxene, absence of igneous glass and interstitial and well‐developed plagioclase, it should be classified as petrologic type 6.Nogata appears lightly shocked, upper b or the border of b and c by Van Schmus and Ribbe's classification, whereas most L6 chondrites are more heavily shocked.Nogata contains rather high amounts of both radiogenic and spallogenic light noble gases, and gives gas retention ages and cosmic‐ray‐exposure ages (e.g.21Ne age) of 4.5 and 4.7 × 103years and 4.00 × 107years, respectively. From such results combined with the light shock effects of Nogata, it is concluded that metamorphism of this chondrite was completed just after the formation of the parent body in a very short interval,>108years, w

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1983.tb00580.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The subgroups within the basaltic achondrite suite are defined using the structural criterion of Wahl (1952). The ‘monomict’ meteorites are samples of a single lithology while the polymict meteorites are those containing two or more lithologies. The ‘monomict’ subgroups eucrites, cumulate eucrites and diogenites are subdivided into both brecciated and unbrecciated meteorites. The polymict achondrites sample a petrological‐compositional continuum that contains both mafic and ultramafic rock types and may be subdivided into several groups. Two groups of polymict basaltic achondrites, the polymict eucrites and howardites are separated using an arbitrarily defined criterion. The recommended criterion is based on the amount of magnesian ortho‐pyroxenite (diogenite) component in the meteorite. Howardites contain more than 10% and polymict eucrites contain less than 10%.The criteria proposed (perhaps with minor variations), appear to reconcile the ambiguities caused by the polymict eucrites. These meteorites, using earlier structural criteria, are howardites, but using mineralogical‐chemical criteria are eucrites. As a subgroup of the polymict achondrites, their relationship with the howardites is clear, and the preservation of the term ‘eucrite’ in their name highlights their modal affinity to the

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1983.tb00581.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Atlanta is the fifth known brecciated enstatite chondrite. It contains a centimeter‐sized troilite‐rich clast, similar to those that occur in Blithfield. All of these clasts probably formed in the solar nebula under high pS2/pO2conditions in a gas of non‐cosmic composition. The absence of ordinary or carbonaceous chondrite clasts in any of the enstatite chondrite breccias and absence of enstatite chondrite clasts or materials formed at high pS2/pO2ratios in ordinary and carbonaceous chondrite breccias support the model that enstatite chondrites were formed at a location distant from those of the other chondritic g

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1983.tb00582.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Lithium contents have been determined by neutron activation analysis in 54 meteorites distributed as: C (9), H (13), L (10), LL (3), E (2), achondrites (11), and stony irons (6). Among the undifferentiated meteorites Li contents range from 1 to 3 ppm. Li contents are higher in Ca‐rich achondrites and mesosiderites than in Ca‐poor achondrites and pallasites respectively. Among achondrites, Li correlates positively with Ca and Al and inversely with Mg. A minor Li‐rich phase might be associated with the plagioclase component of achondrites. In several meteorites Li concentration is determined in magnetic and nonmagnetic fractions, chondrules, and light and dark components (for the gas‐rich mete

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1983.tb00583.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The study of carbon abundance and isotopic composition in extraterrestrial samples is fraught with problems related to contamination in the terrestrial environment and during sample handling. A stepped combustion method is described which demonstrates that progress can be made towards resolving the indigenous species from contamination which for the most part burns at low temperature (<425 ± 25 ±C). The proposed method is not applicable to samples which have indigenous phases burning at low temperatures e.g. the C1 and C2 carbonaceous chondrites. A number of examples where its application is possible are given.Even meteorites collected immediately after their fall, such as Allende, contain a proportion of extraneous carbon which has deleterious effects on any bulk estimate of isotopic composition. “Falls” which have spent a considerable time in museum collections and “finds” (other than Antarctic samples) can be considered as grossly contaminated. Bulk isotope and carbon abundance measurements in the literature for most samples having less than 1 wt% C are thus of questionable value. Antarctic samples have much less contamination of an organic nature but all seem to contain a weathering component which can be easily recognised and hence disregarded in estimates of bulk composition. Stepped combustion, applied to an Apollo 11 lunar soil which has not been specially stored and which now contains, due to contamination, nearly twice as much carbon as when originally collected, can still afford data closely resembling those obtained from the sample when it was first returned

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1983.tb00584.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

A new composition of primordial terrestrial xenon is derived, on the assumption that it lies on an extension of the mixing line between solar Xe and anomalous (CCF) Xe in carbonaceous chondrites. With this composition, the apparent fission components in atmospheric and well gas Xe become larger, and resemble244Pu fission xenon.

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1983.tb00585.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1983.tb00586.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The results obtained from the specimen labelled BRIANZA revealed that it is an artificial iron and not a chondritic meteorite, as previously supposed.

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1983.tb00587.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1983.tb00589.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1983.tb00590.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY