Megalineament in southeastern Alaska marks southwest edge of Coast Range batholithic complex

Canadian Journal of Earth Sciences
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The Coast Range megalineament is a prominent, nearly continuous topographic and structural feature that extends southeastward about 550 km (330 mi) from its junction with the Chatham Strait – Lynn Canal fault at Point Sherman to Tongass Passage near the mouth of Pearse Canal where it leaves southeastern Alaska. It probably extends still further southeastward into British Columbia along Work Channel and Chatham Sound – Grenville Channel.The megalineament is a zone a few hundred metres to 10 km (6 mi) wide in which closely spaced joints, foliation, compositional layering, and small faults define the megalineament trend. The zone usually coincides with topographic depressions apparently caused by selective fluvial and glacial erosion of the less resistant rocks of the zone.Studies in the Juneau, Endicott Arm, and Behm Canal areas indicate that the megalineament (1) is locally the site of lateral and (or) vertical separations of no greater than several kilometres; (2) does not mark a major structural or metamorphic discontinuity in the near-surface rocks; (3) may be located near a pre-metamorphic and pre-intrusive discontinuity; (4) is consistently associated with and parallel to steep gradients in both the gravity and aeromagnetic fields; and (5) probably is the surface expression of the western contact, at depth, of the intrusive rocks and gneisses of the Coast Range batholithic complex with the schists to the southwest.

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Publication type Article
Publication Subtype Journal Article
Title Megalineament in southeastern Alaska marks southwest edge of Coast Range batholithic complex
Series title Canadian Journal of Earth Sciences
DOI 10.1139/e78-184
Volume 15
Issue 11
Year Published 1978
Language English
Publisher Canadian Science Publishing
Contributing office(s) Geology, Minerals, Energy, and Geophysics Science Center
Description 12 p.
First page 1763
Last page 1772
Country United States
State Alaska
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