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Extensional origin of ductile fabrics in the Schist Belt, Central Brooks Range, Alaska—II. Microstructural and petrofabric evidence

Law, Richard D. and Miller, Elizabeth L. and Little, Timothy A. and Lee, Jeffrey (1994) Extensional origin of ductile fabrics in the Schist Belt, Central Brooks Range, Alaska—II. Microstructural and petrofabric evidence. Journal of Structural Geology, 16 (7). pp. 919-940. ISSN 0191-8141. https://resolver.caltech.edu/CaltechAUTHORS:20180316-154525787

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Abstract

A regional system of S-dipping faults is exposed in the Florence and Fall Creeks area of the south-central Brooks Range. This fault system has previously been mapped as the ‘root zone’ of a N-vergent fold-and-thrust belt of Jurassic-Cretaceous age, although individual faults juxtapose lower grade on higher grade metamorphic rocks suggesting apparent extensional geometries. The structurally highest of these faults places rocks of the oceanic Paleozoic-Mesozoic Angayucham terrane, together with unconformably overlying Cretaceous clastic rocks, on Devonian metagreywacke and phyllite. This metagreywacke-phyllite (MP) unit in turn structurally overlies Devonian (?) and older basement rocks of the Brooks Range Schist Belt along a S-dipping structural contact previously mapped as the Florence Creek fault. The Schist Belt and MP units are both characterized by a regionally developed, S-dipping greenschist facies foliation that displays a pronounced N-S-trending, down-dip elongation lineation which earlier workers regarded as being associated with N-vergent thrusting. While only one foliation (S_d) is recognized in the MP unit, in the underlying Schist Belt this foliation (S_2) overprints an earlier blueschist facies mineral assemblage and associated foliation (S_1).


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1016/0191-8141(94)90076-0DOIArticle
https://www.sciencedirect.com/science/article/pii/0191814194900760PublisherArticle
Additional Information:© 1994 Published by Elsevier Ltd. Received 6 May 1992; accepted in revised form 13 September 1993. Fieldwork for this study was funded by a grant from ARCO Alaska to Miller, and made possible by helicopter and logistical support from the Trans-Alaska Crustal Transect Geologic Studies Project of the U.S. Geological Survey headed by T. E. Moore and W. J. Nokleberg during the summers of 1989 and 1990. R. D. Law particularly wishes to thank Richard Gottschalk for generously supplying unpublished data, Dianna Solie of the Alaska Division of Geological and Geophysical Surveys for her hospitality during fieldwork and Delpfine Welch for advice on computer programs. Laboratory work and preparation of data for publication was supported by National Science Foundation Grants EAR-9018929 to R. D. Law and EAR-9018922 to E. L. Miller. Critical reviews by J. Gilotti, R. R. Gottschalk, J. W. Handschy, D. Solie and S. F. Wojtal substantially improved the manuscript and are gratefully acknowledged.
Funders:
Funding AgencyGrant Number
Arco FoundationUNSPECIFIED
NSFEAR-9018929
NSFEAR-9018922
Issue or Number:7
Record Number:CaltechAUTHORS:20180316-154525787
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20180316-154525787
Official Citation:Richard D. Law, Elizabeth L. Miller, Timothy A. Little, Jeffrey Lee, Extensional origin of ductile fabrics in the Schist Belt, Central Brooks Range, Alaska—II. Microstructural and petrofabric evidence, Journal of Structural Geology, Volume 16, Issue 7, 1994, Pages 919-940, ISSN 0191-8141, https://doi.org/10.1016/0191-8141(94)90076-0.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:85350
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:02 Apr 2018 18:45
Last Modified:03 Oct 2019 19:30

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