Kinematics and timing of the Gold Hill fault zone in the vicinity of High Rock Lake, south-central North Carolina

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Title: Kinematics and timing of the Gold Hill fault zone in the vicinity of High Rock Lake, south-central North Carolina
Author: Standard, Issac Daniel
Advisors: Dr. James P. Hibbard, Committee Chair
Abstract: The Gold Hill fault zone is a first-order structure in the Carolina Zone of the southern Appalachians that separates medium grade ductiley deformed rocks of the Charlotte terrane from low grade, mildly deformed rocks of the Carolina terrane. Based on circumstantial evidence, the Gold Hill fault zone has traditionally been viewed as a Devonian dextral shear zone. However, at the western boundary of the Carolina terrane, Late Ordovician, northeast trending, en echelon regional folds are truncated by the north-northeast-trending Gold Hill fault zone. The orientation of these folds relative to the trace of the Gold Hill fault zone suggests previously undocumented early sinistral shear along this major structure. In this vein, new work involving structural mapping and modern kinematic analysis has been undertaken near High Rock Lake, North Carolina in order to investigate the early history of the Gold Hill fault zone. At the western boundary of the Carolina terrane in the vicinity of High Rock Lake, lower to middle greenschist facies rocks of the Albemarle Group are folded about the southwest plunging axis of the Silver Valley syncline and imprinted by a steep northeast-striking axial planar cleavage. In this area, the Gold Hill fault truncates structures associated with the Silver Valley syncline and separates two distinct structural domains. The southwestern domain is characterized by lower to middle greenschist facies unseparated Albemarle Group units deformed by upright, southwest-trending, outcrop-scale folds that contain a steep, north-northeast to northeast striking axial planar cleavage. The folds and cleavage in this domain are similar in geometry and style to the Silver Valley syncline and are interpreted to be genetically related to regional folds in the Carolina terrane. The northwestern domain consists of upper greenschist facies phyllitic volcaniclastic rocks of the western belt. Foliation surfaces in this domain, which strike north-northeast and dip steeply, contain a consistent sub-vertical stretching lineation, as well as a heterogeneously distributed sub-horizontal stretching lineation. Kinematic indicators suggest that motion on the Gold Hill fault zone involved thrusting of the western belt (hanging wall) over the Carolina terrane (foot wall) coupled with a component of sinistral strike-slip motion. These new structural and kinematic relationships suggest Late Ordovician or younger sinistral transpression that may be related to the accretion of the Carolina Zone to Laurentia.
Date: 2003-05-14
Degree: MS
Discipline: Marine, Earth and Atmospheric Sciences
URI: http://www.lib.ncsu.edu/resolver/1840.16/1677


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