U-Pb geochronology of the Acasta Gneiss Complex in Northwest Canada
Name
1028993474-MIT.pdf
Description
Full printable version
Size
23.45 MB
Format
Adobe PDF
Checksum (MD5)
e44b00ef76706a4717fdd786bc5d0556
Author(s)
Safipour, Roxana G
Advisor(s)
Samuel Bowring.
Date Issued
2009
Publisher
Massachusetts Institute of Technology
Abstract
The Acasta Gneiss Complex in Northwest Canada contains the oldest dated rocks in the world. The gneisses range in age from 4.03-3.6 Ga, as determined by U-Pb dating of zircons (Bowring and Williams 1999). U-Pb dating of xenocrystic cores in these zircons indicates a cryptic record of continental crust older than 4.0 Ga. In this study, zircons were selected and characterized from thirteen samples of Acasta Gneisses. Many of the zircons contain xenocrystic cores mantled by younger domains. U-Pb geochronological data were collected using laser ablation inductively coupled plasma mass spectrometery (LA-ICPMS). Twelve of the samples show evidence for two distinct crystallization events, one which formed the cores and another in which the mantle domain overgrew the cores. The oldest cores were dated at >4.0 Ga. This provides additional evidence for pre-4.0 Ga crust formation in the late Hadean.
Description
Thesis: S.B., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2009.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 58-59).
Subjects
Earth, Atmospheric, and Planetary Sciences.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
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MIT theses are protected by copyright. They may be viewed, downloaded, or printed from this source but further reproduction or distribution in any format is prohibited without written permission.
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