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Petrology and 40Ar–39Ar dating of shear zones in the Lanterman Range (northern Victoria Land, Antarctica): implications for metamorphic and temporal evolution at terrane boundaries.
- Source :
-
Mineralogy & Petrology . Mar2007, Vol. 89 Issue 3/4, p217-249. 33p. 3 Charts, 6 Graphs, 1 Map. - Publication Year :
- 2007
-
Abstract
- The Lanterman Fault Zone, a major terrane boundary in northern Victoria Land, displays a polyphase structural evolution. After west-over-east thrusting, it experienced sinistral strike-slip shearing. Sheared metabasites from the Wilson Terrane (inboard terrane) preserve a record of retrograde metamorphic evolution. Shearing took place under amphibolite-facies metamorphic conditions (roughly comparable to those reached during regional metamorphism) which later evolved to greenschist-facies conditions. In contrast, the Bowers Terrane (outboard terrane) preserves a prograde metamorphic evolution which developed from greenschist-facies to amphibolite-facies metamorphism during shearing, followed by greenschist-facies metamorphism during the late deformational stages. Laser step-heating 40Ar–39Ar analyses of syn-shear amphibolite-facies amphiboles yielded ages of 480–460 Ma, in agreement with a ∼480-Ma age obtained from a biotite aligned along the mylonitic foliation. These ages are younger than those (∼492 to ∼495 Ma) obtained from pre-shear amphibole relics linked to regional metamorphism of the Wilson Terrane. Results attribute the structural and metamorphic reworking during shearing to the late stages of the Cambrian-Ordovician Ross Orogeny and to the Middle-Late Ordovician probably in relation to the beginning of deformation in the Lachlan Orogen, thus precluding any appreciable impact of the Devonian-Carboniferous Borchgrevink event in the study area. [ABSTRACT FROM AUTHOR]
- Subjects :
- *PETROLOGY
*SHEAR zones
*GEOCHRONOMETRY
*METAMORPHISM (Geology)
*GEOLOGIC faults
Subjects
Details
- Language :
- English
- ISSN :
- 09300708
- Volume :
- 89
- Issue :
- 3/4
- Database :
- Academic Search Index
- Journal :
- Mineralogy & Petrology
- Publication Type :
- Academic Journal
- Accession number :
- 24157380
- Full Text :
- https://doi.org/10.1007/s00710-006-0164-2