The origin and tectonic significance of the mafic-ultramafic association in the central Virginia Blue Ridge post-Grenville cover sequence

The question of whether the mafic and ultramafic rocks of the central Virginia Blue Ridge are part of a Late Proterozoic to Ordovician ophiolite-bearing sequence or part of an intrusive-extrusive sequence related to the Late Proterozoic Iapetan rifting has major implications for Appalachian tectonic models. Current models consider most of the Blue Ridge cover sequence to be ophiolitic mélange that was obducted onto Laurentia, thus implying a suture or terrane boundary is associated with the rocks. Detailed field mapping and petrography of three typical mafic-ultramafic complexes in the central Virginia Blue Ridge (the Catfish, Flat Creek, and Schuyler complexes) indicate that these bodies do not show characteristics that resemble ophiolites. The three complexes are broadly conformable with stratigraphic layering, and the Lynchburg Group host strata form a continuous and conformable stratigraphic sequence unbroken by faults and without evidence of mélange. Contacts between the mafic-ultramafic bodies and the host rocks are sharp and show no strong evidence for faulting or other disturbances. Internal contact relations and the presence of autoliths indicate that these bodies were derived from multiple injection of a fractionating basaltic magma. The characteristics of the Catfish, Flat Creek, and Schuyler complexes confirm that the mafic-ultramafic association is an intrusive sequence rocks intimately related to the Late Proterozoic Iapetan rifting. The rocks are not part of a Late Proterozoic to Ordovician ophiolite sequence or mélange. Therefore, there are no sutures or terrane boundaries in the central Virginia Blue Ridge.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Geological Sciences

Department dc:contributor.department

Geological Sciences

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

1996

Author dc:creator

• Thompson, Wendi R.

Chairs dc:contributor.committeechair

• Glover III, L.
• Law, Richard D.

Committee members dc:contributor.committeemember

• Bekken, B.
• Eriksson, Kenneth
• Gates, A.E.

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en

Dc Identifier Other

etd-08292008-063748

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/44509