Age of xenocrystic zircon from diatremes of western Canada

Autor:	I. Reichenbach, R. R. Parrish
Rok vydání:	1991
Předmět:	Diatreme geography geography.geographical_feature_category Paleozoic Proterozoic Archean Geochemistry General Earth and Planetary Sciences Xenolith Crust Sedimentary rock Geology Zircon
Zdroj:	Canadian Journal of Earth Sciences. 28:1232-1238
ISSN:	1480-3313 0008-4077
DOI:	10.1139/e91-110
Popis:	Numerous diatremes of middle and late Paleozoic age intrude miogeoclinal middle and lower Paleozoic strata in the Canadian Cordillera. In addition to abundant crustal xenoliths and conspicuous mantle-derived mineral xenocrysts, rare zircon grains are present. U–Pb dating of single zircon crystals from many of these diatremes has failed to identify the presence of cogenetic (magmatic) zircons. All dated zircon grains are interpreted as xenocrysts derived from the crust. Their morphologies range from euhedral to very rounded, and their ages range from early Paleozoic to Archean. Most ages fall between 1.8 and 2.1 Ga, with subordinate age groupings in the late Archean (ca. 2.6 Ga), Middle Proterozoic (1.0–1.1 Ga), and early Paleozoic (ca. 470 Ma, 530 Ma). The Proterozoic and Archean zircons could have been derived from either the crystalline basement or its overlying sedimentary cover of Late Proterozoic to early Paleozoic age. Paleozoic zircons were probably derived from either intrusions within the basement or sills that intrude the early Paleozoic sedimentary cover, and they signify magmatic activity possibly related to rifting of the continental margin.
Databáze:	OpenAIRE
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