Monazite petrochronology of polymetamorphic granulite‐facies rocks of the Larsemann Hills, Prydz Bay, East Antarctica

2021 ◽  
Author(s):  
Steven K. Spreitzer ◽  
Jesse B. Walters ◽  
Alicia Cruz‐Uribe ◽  
Michael L. Williams ◽  
Martin G. Yates ◽  
...  
Keyword(s):  
Granulite Facies ◽  
East Antarctica ◽  
Prydz Bay ◽  
Larsemann Hills

Imaging the Ice Sheet and Uppermost Crustal Structures with a Dense Linear Seismic Array in the Larsemann Hills, Prydz Bay, East Antarctica

2021 ◽  
Author(s):  
Lei Fu ◽  
Jingxue Guo ◽  
Junlun Li ◽  
Bao Deng ◽  
Guofeng Liu ◽  
...  
Keyword(s):  
High Resolution ◽  
Ice Sheet ◽  
Velocity Model ◽  
Dispersion Curves ◽  
Body Waves ◽  
East Antarctica ◽  
Prydz Bay ◽  
Larsemann Hills ◽  
Geophysical Surveys ◽  
Short Period

Abstract Comprehensive geophysical surveys including magnetotelluric, seismic, and aerial gravity–magnetic surveys are essential for understanding the history of Antarctic tectonics. The ice sheet and uppermost structure derived from those geophysical methods are relatively low resolution. Although ice-penetrating radar can provide high-resolution reflectivity images of the ice sheet, it cannot provide constraints on subice physical properties, which are important for geological understanding of the Antarctic continent. To obtain high-resolution images of the ice sheet and uppermost crustal structure beneath the Larsemann Hills, Prydz Bay, East Antarctica, we conduct an ambient noise seismic experiment with 100 short-period seismometers spaced at 0.2 km intervals. Continuous seismic waveforms are recorded for one month at a 2 ms sampling rate. Empirical Green’s functions are extracted by cross correlating the seismic waveform of one station with that of another station, and dispersion curves are extracted using a new phase-shift method. A high-resolution shear-velocity model is derived by inverting the dispersion curves. Furthermore, body waves are enhanced using a set of processing techniques commonly used in seismic exploration. The stacked body-wave image clearly shows a geological structure similar to that revealed by the shear-wave velocity model. This study, which is the first of its kind in Antarctica, possibly reveals a near-vertical intrusive rock covered by an ice sheet with a horizontal extent of 4 km. Our results help to improve the understanding of the subice environment and geological evolution in the Larsemann Hills, Prydz Bay, East Antarctica.

The deformational history of the Larsemann Hills, Prydz Bay: the importance of the Pan-African (500 Ma) in East Antarctica

1993 ◽  
Vol 5 (2) ◽  
pp. 179-192 ◽  
Author(s):  
Paul H. G. M. Dirks ◽  
Chris J. Carson ◽  
Chris J. L. Wilson
Keyword(s):  
Water Pressure ◽  
Granulite Facies ◽  
East Antarctica ◽  
Main Stage ◽  
Melt Crystallization ◽  
Early Form ◽  
Alteration Zones ◽  
Larsemann Hills ◽  
Pan African ◽  
Complex Structural

The Larsemann Hills represent a low-pressure granulite terrain with a complex structural-metamorphic history that comprises two parts: 1) granulite facies D1 structures transposed within an early form surface that probably formed at 1000 Ma, and 2) a sequence of progressive, upper amphibolite to lower granulite facies D2–D6 structures that formed during the Pan-African at 500 Ma and were associated with the emplacement of granites and pegmatites with high-grade alteration zones. D2–D6 events comprise an early form surface that has been tightly folded and sheared twice after which it was warped and transected by discrete mylonites. D2–D6 assemblages are associated with decompression textures on D1 peak-assemblages, such as cordierite coronas on garnet + sillimanite in metapelite and plagioclase coronas on garnet in metabasite. This suggests that D2–D6 formed at slightly lower pressures than D1 structures. However, the spatial correlation between the coronas and alteration zones around pegmatitic intrusives indicates that the apparent decompression textures may have partly resulted from transient fluxes in water pressure following melt crystallization. Throughout East Antarctica tectonic provinces have been recognized in which the 1000 Ma tectonothermal events are identified as the main stage in the evolution, and Pan-African events are dismissed as a minor thermal overprint. Although the Larsemann Hills are small in area, they are representative of a great many granulite terrains in East Antarctica, and suggest that great care is needed in the structural-metamorphic analysis of such terrains to ensure the separation of tectonic stages before an interpretation of the tectonic path is attempted.

New constraints from U–Pb, Lu–Hf and Sm–Nd isotopic data on the timing of sedimentation and felsic magmatism in the Larsemann Hills, Prydz Bay, East Antarctica

2012 ◽  
Vol 206-207 ◽  
pp. 87-108 ◽  
Author(s):  
Edward S. Grew ◽  
Christopher J. Carson ◽  
Andrew G. Christy ◽  
Roland Maas ◽  
Greg M. Yaxley ◽  
...  
Keyword(s):  
East Antarctica ◽  
Prydz Bay ◽  
Isotopic Data ◽  
Larsemann Hills
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