ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1977.tb00334.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

The Kramer Creek, Colorado, chondrite was found in 1966 and identified as a meteorite in 1972. Bulk chemical analysis, particularly the total iron content (20.36%) and the ratio of Fetotal/SiO2(0.52), as well as the compositions of olivine (Fa21.7) and orthopyroxene (Fs18.3) place the meteorite into the L‐group of chondrites. The well‐defined chondritic texture of the meteorite, the presence of igneous glass in the chondrules and of low‐Ca clinopyroxene, as well as the slight variations in FeO contents of olivine (2.4% MD) and orthopyroxene (5.6% MD) indicate that the chondrite belongs to the type 4 petrologic

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1977.tb00335.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Happy Canyon [found: 1971, 34° 46.5′N, 101° 33.6′W, Texas] consists of about 85 vol. % enstatite (Fs 0.4%), 5 to 10 vol % plagioclase (An 26%), and 5 vol % diopside (Fs 0.9%). In addition, there are minor remnants of metal (Ni 6.35 wt %, Si‐free) and troilite (with 5.10 wt % Cr and 1.15 wt % Ti) that have survived extensive terrestrial weathering. The meteorite has a cumulate texture, uniform‐size euhedral, prismatic crystals of enstatite (0.3 to 0.4 mm long) with interstitial plagioclase, diopside, troilite, and metal. The enstatite crystals are dominantly disordered and occur in alignments that suggest flow. There are no chondrules or remnants of chondrules. The enstatite crystals contain internal negative crystal voids, which are charactieristic of enstatite achondrites, as well as internal branching submicron rivulet dislocations. The bulk composition is that of an E6 enstatite chondrite, however, it has the texture of a crystal cumulate; achondritic, but unlike that of enstatite achondrites. Glass of a granitic composition occurs mainly in the mesostasis and is compositionally like the glass found inside pyroxene crystals in the Cumberland Falls enstatite achondrite.Happy Canyon is most simply explained as an E6 composition that has melted and reprecipitated at a slightly higher oxidation state, at some depth (>7 km), possibly in the core volume of a small, asteroidal‐size parent body. In terms of classification, it occupies the gap between the recrystallized enstatite chondrites and the igneous, crystalline, unbrecciated enstatite achondrites like Shallowater. Happy Canyon is a new type of enstatit

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1977.tb00336.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Supuhee is a shocked and brecciated H6 chondrite containing foreign lithic clasts. Three such clasts were analysed with the electron microprobe in an attempt to locate “mysterite,” a volatile‐rich material postulated to be present in Supuhee. Clast 1 bears chemical and mineralogical similarities to C1 and C2 chondrites, but its total volatile content,<9.4%, is lower than that of either of these types. The composition of Clast 2 suggests its derivation from H‐group chondrite material via loss of metal and sulfide. The third clast is apparently a unique meteorite type bearing compositional similarities to both ordinary and enstatite chondrites. The occurrence of these clasts in a highly recrystallized host is evidence for their incorporation after metamorphism. The presence of Clast 1, coupled with this time sequence, indicates that conditions were favorable for the formation, incorporation and preservation of volatile‐rich materials such as

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1977.tb00337.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1977.tb00338.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Elgygytgyn crater (lat. 67–30 N, long. 172–00 E) in remote northeastern Siberia is proposed as the meteorite impact site from which the Australasian tektite strewnfield was splashed. The following points support this interpretation: 1, Elgygytgyn very likely is an impact crater and is of adequate size, 18 km across, to generate tektites; 2, the apex of the strewnfield points towards this crater; 3, the terrane is Mesozoic which fits the age of the tektite parental material from Sr/Rb data; 4, compositional and specific gravity lineations within the strewnfield are directed, in part, toward this crater; 5, the high velocity tektites, australites, are distal with respect to this crater while the low velocity tektites, splash forms and Muong Nong tektites, are proximal; 6, the loess deposits and mixed acid/basic rocks of the impact site provide a suitable subgraywacke‐type source material; 7, the erosional state of Elgygytgyn suggests that its age may well be in accordance with that of the Australasian tektite event, i.e., 700,000

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1977.tb00339.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1977.tb00340.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY