gg-dstng

1
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
• GeoPrisms focus site

Iapetus
Grenville
Peri-Gondwanan
Alleghanian
Taconic/Acadian

lt
Atlantic
mod from Hatcher (2002)
USGS Circ. 1264 (2004)
2
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, ICEs Augment active
tectonic models through their fossil aftermath
3
Geomagnetic Induction Arrows, 3867 s
Geomagnetic Induction Sites (Mareschal et al.,
1983)

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
4
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 2D forward models suggest main
conductivity lies in lower crust, but hard to
resolve from GMV alone
Seismicity avoids conductor
5
Fischer et al. (2010)

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