Significance of dextral reactivation of an E-W transfer fault in the formation of the Pennsylvania orocline, central Appalachians

Yeh, M.-W., and Bell, T.H. (2004) Significance of dextral reactivation of an E-W transfer fault in the formation of the Pennsylvania orocline, central Appalachians. Tectonics, 23 (5009). pp. 1-17.

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Abstract

Three hypotheses for orocline development including (1) primary plate boundary shape, (2) arc rotation, and (3) arc overprinting were evaluated for the formation of the Pennsylvania orocline, Maryland, USA, using foliation intersection/inflection axes preserved within porphyroblasts (FIA). The distribution and the timing of sequences of FIA data measured from garnet porphyroblasts within the Loch Raven formation are statistically the same across the Pennsylvania orocline, suggesting that all subregions of the arc have experienced the same deformation history. This may suggest that the geometry of the paleocontinental margin controlled the basic shape of this orocline. However, if the orocline is treated as three separate regions, defined by the SW-WE-NE trending portions of its slightly staircase-shaped outline, a much higher proportion of the NNE-SSW trending FIAs (set II) are preserved in the W-E trending region than those to either side. This geometric relationship could have resulted from WNW-ESE directed bulk stress causing a zone of dextral shear along what is now the W-E trending portion of this orogen. It appears that what could have been an early formed W-E trending sinistral transform shear zone was preferentially dextrally reactivated during the Taconian orogeny.

Item ID: 4483
Item Type: Article (Refereed Research - C1)
ISSN: 1944-9194
Date Deposited: 10 Jun 2009 02:19
FoR Codes: 04 EARTH SCIENCES > 0403 Geology > 040312 Structural Geology @ 100%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970104 Expanding Knowledge in the Earth Sciences @ 100%
Citation Count from Web of Science Web of Science 6
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