Constriction structures related to viscous collision, southern Prince Charles Mountains, Antarctica

Corvino, Adrian F., Boger, Steven D., and Fay, Clement (2016) Constriction structures related to viscous collision, southern Prince Charles Mountains, Antarctica. Journal of Structural Geology, 90. pp. 128-143.

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Macroscopic structures are investigated in a zone of highly contorted migmatites from the southern Prince Charles Mountains, Antarctica. Here, L-tectonite fabrics, rods, mullions, boudin pods, elongate enclaves, and fold hinges, are persistent linear features all plunging gently to the northeast. In contrast, amoeboid folds, ptygmatic folds and folded boudins with different orientations are the characteristic structures in transverse sections (perpendicular to the lineation). No consistent shear sense is recognised in any dimension. Together with strain and shape analysis, these observations strongly suggest that the deformation pattern is one of folding and stretching by constriction. Previous timing constraints indicate that this deformation overlapped with the waning stages of anatexis during decompression at approximately 510 Ma, up to 30 million years after initial orogeny at 540 Ma. The zone affected by constriction is several kilometres wide and has a contorted flower-like shape confined between two broad domal antiforms. In this context, the constricted zone is interpreted as a relatively late tectonic feature that could have formed via deep-seated viscous collision in response to orogenic collapse and doming.

Item ID: 46100
Item Type: Article (Research - C1)
ISSN: 1873-1201
Keywords: migmatite, stretching lineation, l-tectonite, ptygmatic fold, amoeboid fold, constrictive deformation
Funders: South Australian Museum (SAM)
Projects and Grants: SAM AAS project 2355
Date Deposited: 19 Oct 2016 07:50
FoR Codes: 37 EARTH SCIENCES > 3705 Geology > 370511 Structural geology and tectonics @ 100%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970104 Expanding Knowledge in the Earth Sciences @ 100%
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