Petrology and structure of shear-controlled anatexites in migmatite

Conference · Tue Jan 01 04:00:00 EST 1985 · Geol. Soc. Am., Abstr. Programs; (United States)

OSTI ID:6070271

Size, W B; Covert, J

A close spatial relationship exists between small-scale shear structures and anatexites. The shear structures appear to provide the pathways for the release of incipient anatectic melt as well as subsequent coalescing. Braid-like interconnections of melt develop into larger-scale zones of neosome which cut older migmatite. These patterns are present in the Mount Arabia migmatite, a granitic phase of the Lithonia Gneiss, which covers more than 1800 square kilometers of the Inner Piedmont of Georgia. Mapped at a scale of 1:50, selected areas of the Mount Arabia migmatite display several stages of progressive melting from incipient metatectic films parallel to gneissic bands, to arterites composed of over 30% neosome. The migmatite shows macroscopic structural heterogeneity which appears to be related to the degree of remelting. Zones of high melt proportion consist of more ductilly deformed gneiss with contorted banding, buckle folding, mafic schlieren and pods of nebulitic migmatite. Except for its lower biotite percentage, the composition of the anatectic granite is the same as the gneiss. The petrologic and structural modification history in the Mount Arabia migmatite can be reconstructed using the composite effects of partial melt segregation, restite disaggregation, re-equilibration and contrasts in structural competance.

• Research Organization: Emory Univ., Atlanta, GA (USA)
• OSTI ID: 6070271
• Report Number(s): CONF-8510489-
• Conference Information: Journal Name: Geol. Soc. Am., Abstr. Programs; (United States) Journal Volume: 17
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580300* -- Mineralogy
Petrology
& Rock Mechanics-- (-1989)
BIOTITE
CHALCOGENIDES
CRYSTAL STRUCTURE
FEDERAL REGION IV
FELDSPARS
GEOLOGIC HISTORY
GEOLOGY
GEORGIA
GNEISSES
GRANITES
IGNEOUS ROCKS
MECHANICAL PROPERTIES
MELTING
METAMORPHIC ROCKS
METAMORPHISM
MICA
MICROSTRUCTURE
MINERALOGY
MINERALS
NORTH AMERICA
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PARAGENESIS
PETROGENESIS
PETROLOGY
PHASE TRANSFORMATIONS
PLUTONIC ROCKS
QUARTZ
RECRYSTALLIZATION
ROCKS
SHEAR
SHEAR PROPERTIES
SILICATE MINERALS
SILICON COMPOUNDS
SILICON OXIDES
USA