Extent of the Ross Orogen in Antarctica: new data from DSDP 270 and Iselin Bank.

Mortimer, N., Palin, M., Dunlap, J. and Hauff, Folkmar (2011) Extent of the Ross Orogen in Antarctica: new data from DSDP 270 and Iselin Bank. Antarctic Science, 23 (3). pp. 297-306. DOI 10.1017/S0954102010000969. Date online first: 2011

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Abstract

The Ross Sea is bordered by the Late Precambrian–Cambrian Ross–Delamerian Orogen of East Antarctica and the more Pacific-ward Ordovician–Silurian Lachlan–Tuhua–Robertson Bay–Swanson Orogen. A calcsilicate gneiss from Deep Sea Drilling Project 270 drill hole in the central Ross Sea, Antarctica, gives a U-Pb titanite age of 437 ± 6 Ma (2σ). This age of high-grade metamorphism is too young for typical Ross Orogen. Based on this age, and on lithology, we propose a provisional correlation with the Early Palaeozoic Lachlan–Tuhua–Robertson Bay–Swanson Orogen, and possibly the Bowers Terrane of northern Victoria Land. A metamorphosed porphyritic rhyolite dredged from the Iselin Bank, northern Ross Sea, gives a U-Pb zircon age of 545 ± 32 Ma (2σ). The U-Pb age, petrochemistry, Ar-Ar K-feldspar dating, and Sr and Nd isotopic ratios indicate a correlation with Late Proterozoic–Cambrian igneous protoliths of the Ross Orogen. If the Iselin Bank rhyolite is not ice-rafted debris, then it represents a further intriguing occurrence of Ross basement found outside the main Ross–Delamerian Orogen.

Document Type: Article
Keywords: Petrology; Volcanology; Antarctica, metamorphic rocks, igneous rocks, geochronology, geochemistry, tectonics, Ross Orogen, Lachlan Orogen
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS Magmatic and Hydrothermal Systems
OceanRep > The Future Ocean - Cluster of Excellence
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1017/S0954102010000969
ISSN: 0954-1020
Projects: Future Ocean
Date Deposited: 25 Nov 2010 15:27
Last Modified: 05 Sep 2016 13:42
URI: http://oceanrep.geomar.de/id/eprint/10148

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