Catalogo Articoli (Spogli Riviste)

OPAC HELP

Titolo:
Origin and evolution of mid- to late-Archean crust in the Hanikahimajuk Lake area, Slave Province, Canada; evidence from U-Pb geochronological, geochemical and Nd-Pb isotopic data
Autore:
Yamashita, K; Creaser, RA; Jensen, JE; Heaman, LM;
Indirizzi:
Univ Alberta, Dept Earth & Atmospher Sci, Edmonton, AB T6G 2E3, Canada Univ Alberta Edmonton AB Canada T6G 2E3 Sci, Edmonton, AB T6G 2E3, Canada
Titolo Testata:
PRECAMBRIAN RESEARCH
fascicolo: 3-4, volume: 99, anno: 2000,
pagine: 197 - 224
SICI:
0301-9268(200002)99:3-4<197:OAEOMT>2.0.ZU;2-#
Fonte:
ISI
Lingua:
ENG
Soggetto:
YELLOWKNIFE GREENSTONE-BELT; NORTHWEST-TERRITORIES; SUBDUCTION-ZONE; DEEP CRUST; ROCKS; COMPLEX; ZIRCON; AGE; CONSTRAINTS; MELTS;
Keywords:
Archean; geochemistry; geochronology; Nd isotope; Pb isotope; Slave province;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
79
Recensione:
Indirizzi per estratti:
Indirizzo: Yamashita, K Harvard Univ, Dept Earth & Planetary Sci, 20 Oxford St, Cambridge, MA 02138 USA Harvard Univ 20 Oxford St Cambridge MA USA 02138 MA 02138 USA
Citazione:
K. Yamashita et al., "Origin and evolution of mid- to late-Archean crust in the Hanikahimajuk Lake area, Slave Province, Canada; evidence from U-Pb geochronological, geochemical and Nd-Pb isotopic data", PRECAMB RES, 99(3-4), 2000, pp. 197-224

Abstract

A geochronological, major/trace element geochemical and Nd-Pb isotopic study of early- to mid-Archean basement granitoids/gneisses, similar to 2.68 Ga greenstone belt and 2.58-2.62 Ga late-Archean granitoids from the Hanikahimajuk Lake area of the northern Slave province was undertaken to constrainthe tectonomagmatic evolution of the northcentral area of Slave province, Northwest Territories, Canada. The basement tonalites are precisely dated at 3378 +/- 1 Ma by U-Pb zircon methods and are characterized by steeply fractionated REE patterns with no negative Eu anomalies. They were likely produced through partial melting of mafic crust at >0.8 GPa. The epsilon Nd-T of these rocks range from -0.3 to +2.1, implying involvement of even older crustal material in their genesis. Two different types of similar to 2.68 Gamafic to intermediate volcanic rock are recognized in the Hanikahimajuk Lake area: tholeiitic rocks with no Ta-Nb depletions and calc-alkaline rocks with slight negative Ta-Nb depletions. All of these rocks show clear evidence for contamination by the similar to 3.4 Ga basement tonalite, thus precluding the possibility that some of these tholeiitic mafic rocks were produced in a mid-oceanic ridge setting. From the data presented here, we conclude that the tholeiitic rocks were produced in a back-are setting, likely similar to that of the Japanese are. The calc-alkaline rocks may either be a remnant of the volcanic are or part of the same back-are system. However, the close proximity with the tholeiitic rocks in the field favours the latterpossibility. Mafic to intermediate rocks with similar geochemical and isotopic characteristics are also found from the Yellowknife area of the southwestern Slave province, and from the Indin Lake area of the westernmost Slave province (south of Grenville Lake area). This observation may indicate that the mafic-dominated volcanic belts of the western Slave province may be a remnant of a single, now collapsed and shortened back-are basin. The existence of syn-volcanic calc-alkaline plutonic rocks with similar geochemicaland isotopic features as the calc-alkaline volcanic rocks supports this possibility. The geochemistry of late-Archean granitoids suggests that they are produced mainly through partial melting of mafic igneous protoliths and elastic sedimentary rocks (and possibly tonalitic rocks). Similarity in theepsilon Nd(2.6) values between these granitoids and the supracrustal rocksin the area is in accord with this model. Such protoliths are also consistent with the tectonic setting at which the similar to 2.68 Ga volcanic rocks were generated, because mafic igneous rocks and elastic sedimentary rocks(with lesser felsic igneous rocks) are the major constituents of a back-are basin. (C) 2000 Elsevier Science B.V. All rights reserved.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 10/07/20 alle ore 01:59:21