Oxygen isotope perspective on Precambrian crustal growth and maturation

Journal Article · Sat Apr 01 04:00:00 EST 2000 · Geology

DOI:https://doi.org/10.1130/0091-7613(2000)028<0363:OIPOPC>2.3.CO;2· OSTI ID:20030505

Peck, W H; King, E M; Valley, J W

In this study the authors contrast insights on Precambrian crustal growth and maturation from radiogenic and oxygen isotope systematics in the Superior (3.0--2.7 Ga) and Grenville (1.3--1.0 Ga) Provinces of the Canadian shield. Oxygen isotope ratios in zircon provide the best evidence of supracrustal input into ancient orogens. Archean Superior Province zircons have relatively low {delta}{sup 18}O values and a limited range (5.7{per_thousand} {+-} 0.6{per_thousand}), while Proterozoic Grenville Province zircons have elevated {delta}{sup 18}O values and a wider range (8.2{per_thousand} {+-} 1.7{per_thousand}). These data reflect fundamental differences in crustal evolution and maturation between the Superior and the Grenville Provinces. In the Grenville Province, radiogenically juvenile supracrustal material with high {delta}{sup 18}O values was buried (or subducted) to the base of the crust within 150 m.y. of initial crust production, causing high magmatic {delta}{sup 18}O values ({delta}{sup 18}O [zircon] {ge} 8{per_thousand}) in anorthosite suite and subsequent plutons. Information about large volumes and rapid recycling of Grenville crust is not accessible from radiogenic isotope data alone. The Grenville data contrast with the restricted {delta}{sup 18}O values of Superior Province magmatism, where subtle ({approximately}1{per_thousand}) elevation in {delta}{sup 18}O occurs only in volumetrically minor, late to postorogenic (sanukitoid) plutons. Differences in sediment {delta}{sup 18}O values between the Superior and Grenville Provinces are predominantly a function of the {delta}{sup 18}O of source materials, rather than differences in chemical maturity or erosion styles. This study shows that zircon is a robust reference mineral to compare igneous processes in rocks that have undergone radically different histories.

• Research Organization: Univ. of Wisconsin, Madison, WI (US)
• Sponsoring Organization: National Science Foundation; US Department of Energy
• OSTI ID: 20030505
• Journal Information: Geology, Journal Name: Geology Journal Issue: 4 Vol. 28; ISSN 0091-7613; ISSN GLGYBA
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
CANADA
CONTINENTAL CRUST
GEOLOGIC HISTORY
ISOTOPE RATIO
ORIGIN
OXYGEN 18
ZIRCON