Title Elastic properties of high-grade metamorphosed igneous rocks from Enderby Land and eastern Dronning Maud Land, Antarctica; evidence for biotite-bearing mafic lower crust
Author Ishikawa, M.; Shingai, E.; Arima, M.
Author Affil Ishikawa, M., Yokohama National University, Graduate School of Environment and Information Sciences, Yokohama, Japan. Other: National Institute of Polar Research, Japan; Kyushu University, Japan; Chiba University, Japan
Source Geodynamic evolution of East Antarctica; a key to the east-west Gondwana connection, edited by M. Satish-Kumar, Y. Motoyoshi, Y. Osanai, Y. Hiroi and K. Shiraishi. Geological Society Special Publications, Vol.308, p.183-194, . Publisher: Geological Society of London, London, United Kingdom. ISSN: 0305-8719. ISBN: 978-1-86239-268-7
Publication Date 2008
Notes In English. 42 refs. Ant. Acc. No: 85820
Index Terms Antarctica--East Antarctica; Antarctica--Mount Riiser-Larsen; Antarctica-- Queen Maud Land; Antarctica; Archean; body waves; continental crust; crust; density; East Antarctica; eastern Queen Maud Land; elastic constants; elastic properties; elastic waves; Enderby Land; gneisses; granulites; high pressure; high temperature; igneous rocks; International Polar Year 2007- 08; IPY 2007-08 Research Publications; lower crust; mafic composition; metaigneous rocks; metamorphic rocks; mineral composition; Mount Riiser-Larsen; Napier Complex; P-waves; plutonic rocks; Poisson's ratio; Precambrian; pressure; pyroxenite; Queen Maud Land; S- waves; seismic waves; temperature; ultramafics; velocity; velocity structure
Abstract Ultrasonic measurements of P-wave velocity (Vp) and S-wave velocity (Vs) were conducted at high pressures up to 1.0 GPa and high temperatures up to 400C for ultrahigh- temperature (UHT) metamorphosed rocks from Mount Riiser-Larsen, in the Archaean Napier Complex of Enderby Land. The results at 1.0 GPa and 400C are Vp=7.17 km s-1, Vs=4.24 km s-1, Vp/Vs=1.69, Poisson's ratio (sigma )=0.23 for pyroxenite (SiO2=44.2 wt%, density (rho )=3.41 g cm-3); Vp=6.93 km s-1, Vs=3.81 km s-1, Vp/Vs=1.82, sigma =0.28 for mafic granulite (SiO2=52.2 wt%, rho =3.02 g cm-3); Vp=6.88 km s-1, Vs=3.72 km s-1, Vp/Vs=1.85, sigma =0.29 for mafic granulite (SiO2=49.5 wt%, rho =2.88 g cm-3); and Vp=6.17 km s-1, Vs=3.59 km s-1, Vp/Vs=1.72, sigma =0.24 for orthopyroxene-bearing felsic gneiss (SiO2=65.4 wt%, rho =2.68 g cm-3). Vp and Vp/Vs of these UHT rocks are not comparable with the previously proposed seismic velocity model (Vp=6.56 km s-1, Vp/Vs=1.70) for the lower crust beneath the Mizuho Plateau of eastern Dronning Maud Land. Combining the available measured velocity and density data with the seismic velocity profile defined for the Mizuho Plateau, we suggest that relatively low Vp and Vs characteristics of the lower crust beneath the Mizuho Plateau may be attributed to higher abundance of biotite in the mafic lower crustal rocks. It is proposed that the biotite-bearing lower crustal rocks were formed by metasomatic processes associated with Pan-African orogeny.
URL http://hdl.handle.net/10.1144/SP308.9
Publication Type journal article
Record ID 290787