Sm-Nd and U-Pb isotopic constraints for crustal evolution during Late Neoproterozic from rocks of the Schirmacher Oasis, East Antarctica: geodynamic development coeval with the East African Orogeny
Open-File Report
2007-1047-SRP-007
By: V. Ravikant, J.H. Laux, and M.M. Pimentel
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Abstract
Recent post-750 Ma continental reconstructions constrain models for East African Orogeny formation and
also the scattered remnants of ~640 Ma granulites, whose genesis is controversial. One such Neoproterozoic granulite
belt is the Schirmacher Oasis in East Antarctica, isolated from the distinctly younger Pan-African orogen to the south in
the central Droning Maud Land. To ascertain the duration of granulite-facies events in these remnants, garnet Sm-Nd
and monazite and titanite U-Pb IDTIMS geochronology was carried out on a range of metamorphic rocks. Garnet
formation ages from a websterite enclave and gabbro were 660±48 Ma and 587±9 Ma respectively, and those from Stype granites were 598±4 Ma and 577±4 Ma. Monazites from metapelite and metaquartzite yielded lower intercept UPb ages of 629±3 Ma and 639±5 Ma, respectively. U-Pb titanite age from calcsilicate gneiss was 580±5 Ma. These
indicate peak metamorphism to have occurred between 640 and 630 Ma, followed by near isobaric cooling to ~580 Ma.
Though an origin as an exotic terrane from the East African Orogen cannot be discounted, from the present data there is
a greater likelihood that Mesoproterozoic microplate collision between Maud orogen and a northerly Lurio-Nampula
block resulted in formation of these granulite belt(s).
Study Area
| Publication type | Report |
|---|---|
| Publication Subtype | USGS Numbered Series |
| Title | Sm-Nd and U-Pb isotopic constraints for crustal evolution during Late Neoproterozic from rocks of the Schirmacher Oasis, East Antarctica: geodynamic development coeval with the East African Orogeny |
| Series title | Open-File Report |
| Series number | 2007-1047-SRP-007 |
| DOI | 10.3133/ofr20071047SRP007 |
| Year Published | 2007 |
| Language | English |
| Publisher | U.S. Geological Survey |
| Publisher location | Reston, VA |
| Description | 5 p. |
| Larger Work Type | Report |
| Larger Work Subtype | USGS Numbered Series |
| Larger Work Title | Antarctica: A Keystone in a Changing World--Online Proceedings for the Tenth International Symposium on Antarctic Earth Sciences. Santa Barbara, California, U.S.A.--August 26 to September 1, 2007 |
| Other Geospatial | Antarctica |
| Additional Online Files (Y/N) | N |
| Google Analytic Metrics | Metrics page |