17 Crustal Structure, Tectonics, and Geologic Evolution of the Southeastern U.S. II

Thursday, 31 March 2016
1:30 PM - 5:30 PM
Richland A

STRIKE-SLIP FAULTS AND FABRIC VARIATION: IMPLICATIONS FOR STRUCTURAL AND TECTONIC DEVELOPMENT, NORTHERN IRON MOUNTAINS, SOUTHWEST VIRGINIA

Paper number: 17-6
Program: Theme Sessions
Time: 3:10 PM – 3:30 PM

Authors

Abstract

Neoproterozoic to Early Cambrian Chilhowee Group sedimentary rocks in the northern Iron Mountains, southwest Virginia, record structural imbrication and deformation of the Late Paleozoic Alleghanian Orogeny. Mapping along a transect through the Dry Run Gap area, located in Mt. Rogers National Recreation Area, gives detail on the structural development of the area during orogenesis. Outcrop-scale strike-slip faults—with both dextral and sinistral sense and some strike-slip slickenside surfaces overprinting dip-slip surfaces—are present at several locations along the mapped transect. Many of the strike-slip faults trend NNE-SSW, suggesting a component of orogen-parallel motion, while some strike-slip faults trend NW-SE, suggesting the convergent tectonic transport direction. At least one generation of cleavage is present in the region with a dominant NE-SW trend. However, in some domains, more than one cleavage orientation is present, varying from NW-SE to E-W trends, with steep to intermediate dips. Presence of numerous strike-slip faults, and varying cleavage orientation suggest that deformation in the northern Iron Mountains may be due to: 1) multiple phases of deformation; 2) accommodation of a component of orogen-parallel motion by strain partitioning during oblique convergence; or 3) progressive structural change during continued imbrication and interaction with pre-existing continental margin shape during Alleghanian convergence. Further analysis is required to re-evaluate and interpret the role of strike-slip faults and development of varying cleavage orientations during the structural and tectonic progression of the northern Iron Mountains.

Geological Society of America Abstracts with Programs. Vol. 48, No. 3

doi: 10.1130/abs/2016SE-273344

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