摘要:

In this paper we show that the explosive products from O‐shells of massive stars which contain124Xe with large overproduction factors do not contain any of the naturally occurring isotopes of Os and Pb. We show further that the explosive products from C‐shells (explosive carbon burning) do contain Os and Pb along with Xe which is strongly enriched in r‐Xe of anomalous isotopic composition. The composition of Os in this matter is probably s‐like rather than r‐like. Pb in this matter is enriched in208Pb. The results and arguments of this paper have implications for studies of isotopic compositions of Xe, Os, and Pb in residues of the Allende and other carbonaceous c

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1980.tb00168.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

The combination of the O‐shell theory of Heymann and Dziczkaniec and the supernova theory of Woosley and Howard clearly identifies the astrophysical sites for the formation of the anomalous light Xe component in carbonaceous chondrites. These sites are the O‐ and Ne‐shells, and possibly C‐shell of a massive star. Most of the124Xe and126Xe are formed in the O‐shell during hydrostatic core silicon‐burning, when a seed of heavy nuclei is exposed to an effective temperature near T9= 2.0.128Xe is formed via128Ba in the O‐shell, but the amounts appear too small to satisfy the deduced128Xe/124Xe and128Xe/126Xe yield ratios from the chondrites. However, substantial amounts of128Xe can be formed in the adjacent Ne‐ and C‐shells during the explosion. The formation of128Ba in the O‐shell would increase if the (γ, α) photodisintegration rate in128Ba is actually smaller than calculated by Woosley and Howard. Lewis et al. have proposed that the anomalous light Xe component is mass‐fractionated normal Xe. It is in this sense that the process of stellar nucleosynthesis of the present paper mim

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1980.tb00169.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Questions are raised concerning the possible sources of heat necessary for converting martensite to coarse Type III plessite in ordinary chondrites.It is suggested that the unusual Type III plessite in the Kingfisher, Oklahoma black chondrite was formed by partial homogenization of preexisting Type III plessite as a result of shock reheating of the metal into the γ field of the Fe‐Ni phase diagram, rather than by decomposition of shock reheated prior martensite in the α + γ field, as originally proposed by Taylor and Heymann.Because martensite is sporadically distributed within Kingfisher plessite it is suggested that microstructures of this kind be called Type II‐III pl

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1980.tb00170.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

The elements Na, Mg, Al, Si, S, K, Ca, (V), Cr, Mn, Fe, Co and Ni have been determined in 19 Yamato meteorites by spark source mass spectrometry. For comparison the chondrites Allan Hills 7603, Mt Baldr (b) and Holbrook and the achondrites Johnstown, Pasamonte and Stannern also have been analyzed by the same method. By virtue of their chemical composition the Yamato meteorites 74002 and 74144 prove to be ordinary chondrites of type L; 74001, 74103, 74155 and 74156 are ordinary chondrites of type H; 74662 is a carbonaceous chondrite; Yamato 74010, 74011, 74016, 74037, 74097, 74125 and 74136 are diogenites; Yamato 7308(1) is a howardite; and Yamato 74450 is a eucrite. This agrees with earlier classifications based on petrological and mineralogical arguments (Nagata, 1978; Motylewski, 1978). For the chondrites Yamato 74002, 74106, 74144 and the diogenite 74125, however, no previous classifications could be found in the literature.In a Mg‐Al diagram the eucrites, the howardites, the diogenites and the ureilites fall into characteristic fields. This enabled not only the classification of the Yamato achondrites investigated in this paper but also confirmed the previous identification of Yamato 74123 as a ureilite (Hintenberger et al., 1978).A very high chromium content is characteristic of some Yamato diogenites, especially Yamato 74037 (3.4%). Chromium and vanadium are positively correlated in the achondrites investigate

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1980.tb00171.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

The Adams County, Colorado, H5 chondrite contains a lithic fragment, 1 cm in size, that is texturally and mineralogically quite different from the chondritic host. It is composed of: a groundmass of fine‐grained euhedral to subhedral olivine (3–15 μm) and interstitial glass enclosing larger olivine and pyroxene grains (0.15‐0.5 mm; about 15 vol %); an assemblage of enstatite grains (subfragment within) and an assemblage of olivine plus orthopyroxene (a second subfragment); and about 11 vol % grains of mixed troilite and nickel‐iron metal. Analyses yielded these results: (i) olivine grains of the fragment groundmass have a compositional range (Fa12–45) and most grains contain substantial CaO and Cr2O3(∼ 0.20 and 0.30 avg. wt%, respectively); interstitial glass has ∼ 55 wt% SiO2; (ii) larger olivine grains of the fragment are similarly high in CaO and Cr2O3and also have a wide FeO/MgO range; one unusual pyroxene is an Mg‐rich pigeonite; (iii) the metal is martensite in composition (11–14 wt% Ni); and (iv) major and trace element analyses by INAA indicate an H‐group bulk composition for the entire 1 cm lithic fragment.On the basis of its texture and bulk and mineral compositions, the fragment is interpreted to represent unequilibrated H‐group material that was partly melted by impact. The Ca‐ and Cr‐enriched groundmass olivine and interstitial glass resulted from rapid crystallization of the chondritic melt. The Ca‐ and Cr‐enriched larger silicate grains, including the enstatite sub‐fragment and the pigeonite grain, are residual, unmelted clasts from the target material (this is supported by the presence of similar material in actual H3 chondrites). Further impact brecciation of the clast‐laden melt material, and resultant impact‐splashing accounts for the presence of the fragment in the H‐group Adams County host and documents the coexistence of unequilibrated and equilibrated H‐group materia

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1980.tb00172.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.tb00173.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Petrographic, mineralogical and bulk chemical data are presented for three of approximately 25 L‐group chondrites with which we are attempting to define and interpret major element chemical variations in the L‐group. Two of these unbrecciated L6 chondrites ‐ Aïr and Apt ‐ have olivine and feldspar characteristics that testify to shock pressures of approximately 240–260 kb; they contain sparse veins and pockets of glass. The third, Tourinnes‐la‐Grosse, experienced a lower shock pressure and lacks such evide

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1980.tb00174.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.tb00175.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

At various times the Black Stone of the Ka'ba has been considered to be lava, basalt, a meteorite and lately an agate. This paper discusses the possibility that it may consist of impactite glass, derived from the meteoritic craters of Al‐Hadidah, called Waba

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1980.tb00176.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.tb00177.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY