摘要:

The Timmersoi meteorite, a new type L5 hypersthene chondrite from the Niger Republic is described and microprobe analyses of its olivine, orthopyroxene, clinopyroxene, plagioclase, kamacite, taenite, troilite, chromite, whitlockite, chlorapatite and limonite presented. Veins and patches of black “glassy” material are regarded as products of shock melting. In places this material contains immiscible droplets of troilite each with one or more well‐formed crystals of taenite. Calculations indicate equilibrium between olivine and orthopyroxene with a temperature of equilibration of about 8

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1972.tb00418.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

To improve the labelling value of meteoritic names, new meteorites should be assigned geographical names which are not used for other meteorites, which are simple, and, if possible, of mnemonic value. A Committee on Meteoritic Nomenclature should be established to supervise the assignment of new meteorite names, and to assist in the work necessary to confirm that new meteorite finds are not paired with meteorites which were previously cataloged.

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1972.tb00419.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Olivine grains were analysed by microprobe for Si, Ca, Mg, and Fe. Distribution of Mg and Fe is similar to that already established for Type II and III carbonaceous chondrites. Calcium concentration varies by a factor of about 4 and seems to be independent of fayalite content: its range (about 0.1 − 0.45 weight percent) resembles that in the olivines of Murray (Fredriksson and Keil, 1964).Olivines of carbonaceous chondrites are the product of mechanical mixing of pre‐existing crystals (Van Schmus, 1969). More than one fractionation process is necessary to account for Ca variation superimposed on Mg:Fe fractionation observed in Murray, Murchison and Vigar

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1972.tb00420.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

The Landes silicate‐bearing octahedrite is a new find from Grant County, West Virginia. Minerals and their compositions are very similar to those in Odessa‐type silicate inclusions. The angular nature of the inclusions, recrystallization textures, and mineral compositions indicate a “xenolithic” origin for the inc

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1972.tb00421.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1972.tb00422.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1972.tb00423.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

We have carried out reconnaissance gravity surveys across three Mauritanian craters: Aouelloul, an undoubted meteorite crater; Tenoumer, a probable meteorite crater with a unique array of concentric dikes on its outer rim flanks containing xenoliths of country rock showing abundant shock artifacts; and Temimichat Ghallaman, a crater of possible meteorite impact origin. All three have residual negative gravity anomalies associated with their interiors. In all cases the gravity values return to “normal” immediately outside their rims. At Tenoumer the anomaly has the form and magnitude expected for a meteorite crater which has been subsequently in‐filled with unconsolidated sediments to the level of the surrounding country. Maximum depth from the present crater floor to the bottom of the sedimentary fill (top of the original crater floor) is at least 750 feet. With a rim‐rim diameter of 6,300 feet, the origin depth/diameter ratio of about 1:8 is virtually identical with that of Meteor Crater, Arizona. Temimichat, with a rim‐rim diameter of 2,100 to 2,400 feet, is somewhat larger than has been previously reported. If it is meteoritic in origin the gravity data dictate a surprisingly shallow structure, with a depth from the present floor to the original crater floor of 150 feet maximum and an original depth/diameter ratio of 1:15. No positive evidence for an impact origin has yet been found for Temimichat. Aouelloul is also larger than generally reported, with a rim‐rim diameter averaging 1,275 feet. As for Temimichat the gravity data dictate a remarkably shallow structure having a depth/diameter ratio of about 1:13. The combination of a shallow depth and a reasonably high rim apparently requires a scaled depth of burst for the impact event substantially in excess of 0.50, a value previously considered a maximum for explosive impacts. The morphological resemblance between Temimichat and Aouelloul is striking but, without additional evidence, this fact alone cannot be used to infer a sim

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1972.tb00424.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

A crater, 80 m diameter by 6 m deep, was created in 1959 on the Nyika Plateau between Zambia and Malawi. It may have been the result of a meteorite.

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1972.tb00425.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1972.tb00426.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1972.tb00417.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY