摘要:

Abstract—Experimental partial melting of Allende in a modest thermal gradient produces compacted crystalline residues on the cold side and silicate liquid segregations on the hot side of the gradient. The mechanism leading to this segregation is a type of zone refining: thermal migration. Chemical diffusion produces relative migration of phases along a saturation gradient induced by a temperature gradient. The compacted crystals have many features reminiscent of ureilite meteorites: olivine major element compositions, surface‐equilibrium‐controlled adcumulus textures, ripened grain sizes, virtually complete silicate melt removal, and textural elongation. Sulfide melt fails to segregate from crystals by this mechanism. If thermal migration is responsible for the textural features of ureilite compaction, then often‐assumed constraints about ambient gravity fields and cooling regimes do not apply to ureilite origins irrespective of whether the compaction is of a melting residue or a cumulus crystal pile. Certain ingrained expectations relating the geochemistry of complementary liquids to these crystals also will be unsatisfied. Because virtually any crystal consolidation regime operates through a thermal gradient, it is likely that thermal migration must play at least a small role in the process. It would be a particularly appropriate mechanism for consolidating ureilites within planetesimals undergoing vigorous primordial heating by radioactivity or electromagnetic induction—circumstances in which the efficacy of the process is not truncated by cooling. The possible existence of this mechanism does not invalidate less unusual suggestions for the origin of ureilites. However, some of the constraints on ureilite origin and complementary liquid geochemistry are now considerabl

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1988.tb00899.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract—The paper presents the infrared transmission spectrum of the Salzwedel meteorite. Further, the spectrum is used to characterize the meteorite's mineralogical compositio

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1988.tb00900.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Book reviewed in this article:Meteorites and Their Parent Planets by Harry Y. McSween, Jr.Meteorite Craters by Kathleen Mark.Coon Mountain Controversies. Meteor Impact and the Development of the Impact Theory by William Graves Hoyt.The Tucson Meteorites by Richard R. Willey.

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1988.tb00901.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1988.tb00902.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1988.tb00903.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY