PUMA
Istituto di Geoscienze e Georisorse     
Crispini L., Di Vincenzo G., Palmieri R. 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. In: Mineralogy and Petrology, vol. 89 (3-4) pp. 217 - 249. Springer, 2007.
 
 
Abstract
(English)
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.
URL: http://https://link.springer.com/journal/710
Subject Antarctica
Victoria land
Lanterman range
petrology
dating
geological evolution


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