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Sep 17, 2020
STRIKE-SLIP FAULTS AND FABRIC VARIATION: IMPLICATIONS FOR STRUCTURAL AND TECTONIC DEVELOPMENT, NORTHERN
IRON MOUNTAINS, SOUTHWEST VIRGINIA MITCHELL R. SCHARMAN MARSHALL UNIVERSITY
Support from: Marshall University Summer Research Fund
INTRODUCTION
• Small- to mesoscale strike-slip faults present in Dry Run Gap (DRG)
• Variation in cleavage orientation
Map Modified from Bartholomew (1987)
Pulaski Block
Poplar Camp Block
NORTHERN IRON MOUNTAINS - DRY RUN GAP Map Modified from Stose and Stose (1957)
1 2
3
CLEAVAGE VARIATION
STRIKE-SLIP FAULTS
STRIKE-SLIP AND NORMAL FAULTS
STRIKE-SLIP AND NORMAL FAULTS
STRIKE-SLIP AND NORMAL FAULTS
(From Fossen, 2011)
Fault Planes: n = 9
Strike-slip Faults Normal Faults
STRIKE-SLIP OVERPRINT
Fault Planes: n = 16
STRUCTURAL PROGRESSION IMPLICATIONS
• Cleavage variation during convergence • Initial N-NNE Sinistral and Dextral faults • Cut by normal faults - ~W-WNW trending
• Syn-Folding? - Orthogonal Flexure? • Late Strike-slip faults - WNW Sinistral and Dextral
• Syn- to Post-normal fault formation?
Fault Planes: n = 9
Strike-slip Faults Normal Faults
TECTONIC IMPLICATIONS
(From Marshak, 2004) DRG - Tangential Extension?
Map Modified from Bartholomew (1987)
(From Wise & Werner, 2004)
CONCLUSIONS
• Cleavage orientation variation implies progressive structural changes during imbrication
• DRG strike-slip faults indicate a more detailed structural progression • Suggest a change in tectonic transport direction • ~N-NNE to WNW • Possibly accommodating convergence change with salient
interaction
Strike-slip Faults and Fabric Variation: Implications for Structural and Tectonic Development, Northern Iron Mountains, Southwest Virginia Introduction Northern Iron Mountains - Dry Run Gap Cleavage Variation Strike-slip Faults Strike-slip and Normal Faults Strike-slip and Normal Faults Strike-slip and Normal Faults Strike-slip Overprint Structural Progression Implications tectonic Implications Conclusions