Grenville Iapetus

Peri-Gondwanan

Taconic/Acadian

Atlantic

Alleghanian

<=

USGS Circ. 1264 (2004)mod from Hatcher (2002)

Appalachians orogen:- Fossil regimes complementary- Exposed accreted terranes- Cryptic terrane suturing- Laurentian-Paleozoic transition- Upper mantle modification- GeoPrisms focus site

First-order Plan of Appalachian Orogen (Hibbard and Waldron, 2009)

S. Appalachians Suturing and Upper Mantle Modification(Wannamaker, 2005, Surv. Geop.)

MT can: Clarify continental assembly through suture zone mapping Assess mantle modification by purging of volatiles, ICE’s Augment active tectonic models through their fossil aftermath

Deep Crustal Conductivity In Fossil Regimes;Graphite, Sulphide Fluid Remobilization, Shearing

Luque et al. (AJS, 1998)Fluid remobilized graphite

Jones et al. (JGG,1997)Sulphide Stringers

Geomagnetic Induction Arrows, 3867 s Geomagnetic Induction Sites (Mareschal et al., 1983)

Northern Appalachians regional conductor, stronger than in South(Greenhouse and Bailey, 1981)

Depression of Appalachian coast responseindicates compensating interior conductor

Broadscale 2D forward models suggestmain conductivity lies in lower crust, but

hard to resolve from GMV alone

Geomagnetic induction arrows corrected for coast effect

Seismicity ‘avoids’ conductor

Fischer et al.(2010)

- Mantle receiver functions often imply sharp LAB along eastern seaboard- Can conductivity confirm based on hydration or melting?