- Slides: 5
First-order Plan of Appalachian Orogen (Hibbard and Waldron, 2009) Appalachians orogen: - Fossil regimes complementary - Exposed accreted terranes - Cryptic terrane suturing - Laurentian-Paleozoic transition - Upper mantle modification - Geo. Prisms focus site Iapetus Grenville Peri-Gondwanan Alleghanian Taconic/Acadian Atlantic USGS Circ. 1264 (2004) <= mod from Hatcher (2002)
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
Geomagnetic Induction Sites (Mareschal et al. , 1983) Geomagnetic Induction Arrows, 3867 s Luque et al. (AJS, 1998) Fluid remobilized graphite Deep Crustal Conductivity In Fossil Regimes; Graphite, Sulphide Fluid Remobilization, Shearing Jones et al. (JGG, 1997) Sulphide Stringers
Northern Appalachians regional conductor, stronger than in South (Greenhouse and Bailey, 1981) Depression of Appalachian coast response indicates compensating interior conductor Geomagnetic induction arrows corrected for coast effect Broadscale 2 D forward models suggest main conductivity lies in lower crust, but hard to resolve from GMV alone 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?