Upper-crustal orogenic lid and mid-crustal core complexes: signature of a collapsed orogenic plateau in the hinterland of the Grenville Province 1This article is one of a series of papers published in CJES Special Issue: In honour of Ward Neale on the theme of Appalachian and Grenvillian geology.

Author:

Rivers Toby1

Affiliation:

1. Department of Earth Sciences, Memorial University, St. John’s, NL A1B 3X5, Canada.

Abstract

This paper provides a re-interpretation of the crustal architecture of the Ottawan hinterland of the Grenville Province in light of published empirical and numerical models of orogenic collapse. It is now seen as a series of high-grade, mid-crustal core complexes from tens to hundreds of kilometres across that are juxtaposed against segments of the lower grade upper and uppermost crust including the orogenic lid. Juxtaposition of such contrasting crustal levels, which exhibit decoupled tectonic styles corresponding to the orogenic infrastructure and suprastructure, respectively, is interpreted as a signature of the foundering of an orogenic plateau into a mid-crustal channel. Ottawan metamorphism progressed from granulite-facies in the mid crust at ∼1090–1050 Ma, through amphibolite-facies in the upper crust at ∼1050–1020 Ma, to heating to ≤500 °C in the uppermost crust at ∼1020–980 Ma. This temporal progression is interpreted to reflect conductive heat transfer during collapse, as hot mid-crustal core complexes were exhumed against successively higher crustal levels. Exhumation was facilitated by substantial thinning and lengthening of the mid crust by simple- and pure-shear mechanisms. This was accompanied by wholesale boudinage of the brittle uppermost crust. Moreover, it may have resulted in excision of part of the ductile upper crust, which appears under-represented. Collapse was accompanied by diverse magmatic and hydrothermal products, their range of structural states implying that high-strain Ottawan deformation in the mid crust took place beneath an orogenic lid that was not penetratively deformed. Preliminary analysis indicates the Grenvillian inliers exhibit a comparable range of crustal levels to the Grenville Province, suggesting the orogenic plateau may have extended ∼5000 km along strike from Labrador to Texas.

Publisher

Canadian Science Publishing

Subject

General Earth and Planetary Sciences

Reference170 articles.

1. Interpretation of K-Ar mineral dates from Grenville orogenic belt

2. Thermobarometry and Pressure-Temperature Paths in the Grenville Province of Ontario

3. Crustal channel flows: 1. Numerical models with applications to the tectonics of the Himalayan-Tibetan orogen

4. Beaumont, C., Nguyen, M.H., Jamieson, R.A., and Ellis, S. 2006. Crustal flow modes in large hot orogens. In Channel flow, ductile extrusion and exhumation in continental collision zones. Edited by R.D. Law, M.P. Searle, and L. Godin. Geological Society (of London), Special Publication 268. pp. 91–145.

同舟云学术

1.学者识别学者识别

2.学术分析学术分析

3.人才评估人才评估

"同舟云学术"是以全球学者为主线,采集、加工和组织学术论文而形成的新型学术文献查询和分析系统,可以对全球学者进行文献检索和人才价值评估。用户可以通过关注某些学科领域的顶尖人物而持续追踪该领域的学科进展和研究前沿。经过近期的数据扩容,当前同舟云学术共收录了国内外主流学术期刊6万余种,收集的期刊论文及会议论文总量共计约1.5亿篇,并以每天添加12000余篇中外论文的速度递增。我们也可以为用户提供个性化、定制化的学者数据。欢迎来电咨询!咨询电话:010-8811{复制后删除}0370

www.globalauthorid.com

TOP

Copyright © 2019-2024 北京同舟云网络信息技术有限公司
京公网安备11010802033243号  京ICP备18003416号-3