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Titolo:
CRYSTALLINITY AND B(0) SPACING OF K-WHITE MICAS IN A PALEOZOIC ACCRETIONARY COMPLEX, EASTERN AUSTRALIA - METAMORPHISM, PALEOGEOTHERMS, AND STRUCTURAL STYLE OF AN UNDERPLATED SEQUENCE
Autore:
OFFLER R; MILLER JM; GRAY DR; FOSTER DA; BALE R;
Indirizzi:
UNIV NEWCASTLE,DEPT GEOL CALLAGHAN NSW 2308 AUSTRALIA
Titolo Testata:
The Journal of geology
fascicolo: 4, volume: 106, anno: 1998,
pagine: 495 - 509
SICI:
0022-1376(1998)106:4<495:CABSOK>2.0.ZU;2-5
Fonte:
ISI
Lingua:
ENG
Soggetto:
LACHLAN FOLD BELT; SOUTHEASTERN AUSTRALIA; PROGRESSIVE DEFORMATION; SOUTHWEST JAPAN; KODIAK-ISLANDS; SHIMANTO BELT; ALASKA; CALIFORNIA; TECTONICS; SAMPLES;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
65
Recensione:
Indirizzi per estratti:
Citazione:
R. Offler et al., "CRYSTALLINITY AND B(0) SPACING OF K-WHITE MICAS IN A PALEOZOIC ACCRETIONARY COMPLEX, EASTERN AUSTRALIA - METAMORPHISM, PALEOGEOTHERMS, AND STRUCTURAL STYLE OF AN UNDERPLATED SEQUENCE", The Journal of geology, 106(4), 1998, pp. 495-509

Abstract

White micas in slates and meta-sandstones from deformed and imbricated chert-basalt-turbidite sequences of the Narooma Accretionary Complexof the eastern Lachlan Fold Belt, Australia, show b(0) cell values indicative of intermediate P metamorphic facies conditions ((x) over bar= 9.025; n = 73). Illite crystallinity (IC) values indicate middle toupper anchizonal metamorphic conditions and are constant throughout the area. They are in general agreement with the inferred structural position representing the mid-upper levels of a subduction complex. IC values show little change throughout the area, indicating limited vertical displacement on later inferred tectonic breaks. Differences in burial pressure estimates and inferred geothermal gradients occur betweenthe chert-basalt-turbidite sequence (similar to 10 km and 26 degrees C km-l) and the structurally lower chaotic block in-matrix melange (similar to 7 km and 36 degrees C km(-1)). Metamorphism of chaotic block-in-matrix melange is inferred to have occurred at shallow levels closer to the toe of the accretionary complex, in a higher geotherm prior to underplating beneath the chert-basalt-turbidite sequence. Mica crystallization ages from 445-450 Ma indicate subduction activity in the Late Ordovician very close in time to the age of sedimentation.

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Documento generato il 26/09/20 alle ore 11:52:11