Ultramafic to mafic granulites from the Larsemann Hills, East Antarctica: Geochemistry and tectonic implications

The Larsemann Hills area is part of a reworked early Neoproterozoic metamorphic terrain in southwestern Prydz Bay, East Antarctica. Ultramafic and mafic granulites, whose origins remain controversial, occur as lenses, boudins or layered bodies within the para- and ortho-gneiss in the region. The ult...

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Bibliographic Details
Published in:Journal of Asian Earth Sciences
Main Authors: Tong, Laixi, Jahn, Bor-ming, Liu, Xiaohan, Liang, Xirong, Xu, Yi-gang, Ionov, Dmitri
Format: Report
Language:English
Published: PERGAMON-ELSEVIER SCIENCE LTD 2017
Subjects:
Geology
Ultramafic to mafic granulites
Geochemistry
Rayner orogeny (990-900 Ma)
Larsemann Hills
East Antarctica
Geosciences
Multidisciplinary
PRINCE-CHARLES MOUNTAINS
AMERY ICE SHELF
PRYDZ BAY AREA
FACIES METAMORPHISM
RAUER GROUP
BRATTSTRAND BLUFFS
CRUSTAL EVOLUTION
CONTINENTAL-CRUST
VESTFOLD BLOCK
500 MA
Amery
Amery Ice Shelf
Brattstrand Bluffs
Prince Charles Mountains
Prydz Bay
Rauer Group
Rayner
Vestfold
Antarc*
Antarctica
Ice Shelf
Online Access:http://ir.gig.ac.cn/handle/344008/45379
https://doi.org/10.1016/j.jseaes.2017.06.012
Description
Summary:The Larsemann Hills area is part of a reworked early Neoproterozoic metamorphic terrain in southwestern Prydz Bay, East Antarctica. Ultramafic and mafic granulites, whose origins remain controversial, occur as lenses, boudins or layered bodies within the para- and ortho-gneiss in the region. The ultramafic and mafic granulites show spinel-olivine-bearing and two-pyroxene-bearing mineral assemblages recrystallized at 860-900 degrees C. Their bulk rock analyses indicate an origin as igneous cumulates, with high Mg-# (molar MgO/(MgO + FeO)) from 0.73 to 0.84 for ultramafic granulite and from 0.46 to 0.78 for mostly mafic granulite as well as high Cr and Ni contents ([Cr] and [Ni] up to 1826 ppm and 1400 ppm respectively for ultramafic granulite and [Cr] of 1460 ppm for mafic granulite). Trace element patterns show pronounced negative Nb anomalies, suggesting a subduction-related tectonic setting for their precursors, consistent with derivation from arc basalts, also suggested by low TiO2 and K-enrichment in mafic granulites. The ultramafic to mafic granulites may have been formed in a subduction-related continental back-arc basin environment simultaneously with peak metamorphism associated with arc-continent collision during the early Neoproterozoic (990-900 Ma) Rayner orogeny.

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