Title Pre-metamorphic carbon, oxygen and strontium isotope signature of high-grade marbles from the Lützow-Holm Complex, East Antarctica; apparent age constraints of carbonate deposition
Author Satish-Kumar, M.; Miyamoto, T.; Hermann, J.; Kagami, H.; Osanai, Y.; Motoyoshi, Y.
Author Affil Satish-Kumar, M., Shizuoka University, Institute of Geosciences, Shizuoka, Japan. Other: National Institute of Polar Research, Japan; Kyushu University, Japan; Chiba University, Japan; Kyushu University, Japan; Australian National University, Australia; Niigata University, Japan; National Institute of Polar Research, 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.147-164, . Publisher: Geological Society of London, London, United Kingdom. ISSN: 0305-8719. ISBN: 978-1-86239-268-7
Publication Date 2008
Notes In English. 72 refs. Ant. Acc. No: 85818
Index Terms Antarctica--East Antarctica; Antarctica--Queen Maud Land; absolute age; age; Antarctica; C-13/C-12; calcite; carbon; carbonates; cathodoluminescence; dates; dolomite; East Antarctica; geochemistry; high- grade metamorphism; International Polar Year 2007-08; IPY 2007-08 Research Publications; isotope ratios; isotopes; Lutzow-Holm Complex; major elements; marbles; metacarbonate rocks; metals; metamorphic rocks; metamorphism; mineral composition; Neoproterozoic; O-18/O-16; oxygen; Precambrian; Proterozoic; Queen Maud Land; rare earths; Sr/Sr; stable isotopes; thin sections; trace elements; upper Precambrian
Abstract C, O and Sr isotope geochemistry of high-grade marbles from the Lutzow-Holm Complex, East Antarctica, has given clues on the depositional ages and post-depositional alterations. Dolomitic and calcitic marbles occur as thin layers with varying thickness (up to 100 m) in several outcrops in eastern Dronning Maud Land, most of which underwent post-depositional geochemical alterations. In particular, the Sr and O isotope alterations are extensive, with 87Sr/86Sr(550 Ma) ratios as high as 0.758 and delta 18O values as low as -5 per mil. These data suggest that multiple stages of fluid-rock interaction processes during diagenesis, prograde to peak and retrograde metamorphic events have altered the depositional isotopic signatures. However, some of the marble layers, exceptionally, preserve pre-metamorphic geochemical characteristics, such as low Sr isotope ratios, high delta 18O and delta 13C values, and well-equilibrated unaltered trace and rare earth element patterns. Lowest 87Sr/86Sr isotopic ratios of 0.7066 and 0.7053 with high delta 13C and delta 18O values suggest an apparent age of deposition around 730-830 Ma, although total geochemical resetting of carbonates by seawater of this age cannot be ruled out. The apparent depositional ages are consistent with carbonate deposition in the "Mozambique Ocean" that separated East and West Gondwana.
URL http://hdl.handle.net/10.1144/SP308.7
Publication Type journal article
Record ID 290789