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Role of zircon in tracing crustal growth and recyclingSingle crystal ion probe ages of zircons is discussed, which allow much better time resolution compared to other geochronological methods, although the technique is not without problems. Rocks from two areas that contain composite zircon populations, including true magmatic zircons as well as a variety of xenocrystic types are described. It is often difficult to distinguish these; xenocrystic zircons, for example, cannot always be identified on the basis of morphology alone. Additional evidence is needed before making age interpretations. Evidence is also presented of zircon growth long after the original time of crystallization, in some cases apparently at temperatures less than 300 C. The spectacular discovery of 4.1 to 4.2 Ga detrital zircons in metaquartzites from the Mount Narryer area of Western Australia is described. Similar zircons with ages as old as 4276 Ma have been found in the nearby Jack Hills area. The source areas or parent lithologies of these zircons have not yet been determined, but the author expects that they may be unrecognized or buried antecedents of the K rich Narryer gneisses. U or Th concentrations of zircon cannot be used to discriminate between felsic and mafic source rocks.
Document ID
19880020827
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Compston, W.
(Australian National Univ. Canberra., United States)
Williams, I. S.
(Australian National Univ. Canberra., United States)
Armstrong, R. A.
(Australian National Univ. Canberra., United States)
Claoue-Long, J. C.
(Australian National Univ. Canberra., United States)
Kinny, P. D.
(Australian National Univ. Canberra., United States)
Foster, J. J.
(Australian National Univ. Canberra., United States)
Kroener, A.
(Mainz Univ. (Germany, F.R.), United States)
Pidgeon, R. T.
(Western Australian Inst. of Tech. Bentley., United States)
Myers, J. S.
(Western Australian Inst. of Tech. Bentley., United States)
Date Acquired
September 5, 2013
Publication Date
January 1, 1988
Publication Information
Publication: Lunar and Planetary Inst., Workshop on the Growth of Continental Crust
Subject Category
Geophysics
Accession Number
88N30211
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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