The Larsemann Hills, a coastal exposure in southern Prydz Bay.

• Main Authors: C. J. Carson, E. S. Grew, S. D. Boger, C. M. Fanning, A. G. Christy
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Larsemann Hills; Prydz Bay
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.549.3907; http://pubs.usgs.gov/of/2007/1047/ea/of2007-1047ea003.pdf

Summary SHRIMP U-Pb detrital zircon geochronology of a phosphate-rich metaquartzite from the Larsemann Hills, southern Prydz Bay, suggests that the maximum constraint on deposition was latest Neoproterozoic, possibly as young as ca. 550 Ma. The metaquartzite, together with metapelite, metapsammite and boron-rich units, collectively the ‘Brattstrand Paragneiss’, were deposited on composite ca. 1125 Ma and ca. 940-990 Ma felsic orthogneiss basement, which was subsequently interleaved with the metasediments during ca. 515-530 Ma regional high-grade tectonism. The presence of ca. 550-870 Ma rims indicates detrital contribution from sources characteristic of the East African orogen and adjacent regions. The unusual boron and phosphate enrichment in the Neoproterozoic Brattstrand Paragneiss of the Larsemann Hills could have resulted from subseafloor alteration of clastic sediments related to an exhalative-synsedimentary hydrothermal system that mobilised boron from underlying non-marine evaporite borate, suggesting