Strike-slip Faults and Fabric Variation: Implications for Structural … · 2016. 4. 7. · strike-slip faults and fabric variation: implications for structural and tectonic development,

STRIKE-SLIP FAULTS AND FABRIC VARIATION: IMPLICATIONS FOR STRUCTURAL AND TECTONIC DEVELOPMENT, NORTHERN

IRON MOUNTAINS, SOUTHWEST VIRGINIAMITCHELL R. SCHARMANMARSHALL 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)

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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

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