Publication Date

1981

Document Type

Dissertation/Thesis

First Advisor

Berg, Jonathan H.

Degree Name

M.S. (Master of Science)

Department

Department of Geology

LCSH

Geology--Newfoundland--Labrador

Abstract

The Avakutakh iron formation, the basal unit of the Aphebian-aged Falls Brook Group, is exposed in the Snyder Bay - Avakutakh River area of Labrador. Together with the metasedimentary Snyder Group, it forms part of the contact aureole of the Kiglapait intrusion. Thin section study, oxygen isotope analysis, and microprobe analysis were used to determine the petrography, mineral chemistry, and metamorphic history of the Avakutakh iron formation. The Avakutakh iron formation is comprised of three metamorphic zones: grunerite-zone, hypersthene zone, and pigeonite zone. During the metamorphic event, temperatures ranged from 625 - 860°C over a distance of 565 m and pressure was essentially constant at 2.2 kbar. Anomalously low temperatures were obtained from oxygen isotope 18 analysis and appear to be the result of diffusion of ¹⁸O between quartz and magnetite with cooling. Chemical diffusion between the Avakutakh iron formation and adjacent mafic orthogranulites is limited to a band several centimeters wide. Thus, it can be assumed that the Avakutakh iron formation behaved as a closed system with respect to major non-volatile components.

Comments

Includes bibliographical references.||Includes illustrations and maps.

Extent

viii, 169 pages, 23 unnumbered pages

Language

eng

Publisher

Northern Illinois University

Rights Statement

In Copyright

Rights Statement 2

NIU theses are protected by copyright. They may be viewed from Huskie Commons for any purpose, but reproduction or distribution in any format is prohibited without the written permission of the authors.

Media Type

Text

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