A probable Early Triassic age for the Miers Bluff Formation, Livingston Island, South Shetland Islands

Willan, R. C. R.; Pankhurst, R. J.; Hervé, F.. 1994 A probable Early Triassic age for the Miers Bluff Formation, Livingston Island, South Shetland Islands. Antarctic Science, 6 (3). 401-408.

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Fifteen samples of very low-grade mudstones from two widely separated sections in the Miers Bluff Formation on Hurd Peninsula yield an Rb-Sr errorchron (MSWD=8.9) corresponding to an age of 243 ± 8 Ma. This age is interpreted as representing effective homogenization, on a kilometres scale, during turbidite deposition and diagenesis in early Triassic times. The initial 87Sr/86Sr ratio 0.7085 ± 0.0003 represents a mature crustal source and is consistent with the re-working of material comparable to that eroded from the Chilean fore-arc accretionary complex. Four further samples, collected near to a zone of quartz-carbonate veins, lie to the right of the errorchron, with two samples having unusually low Sr contents. These samples fall on a 113 Ma reference line and indicate metasomatic disturbance in Cretaceous times. Metasomatism was probably related to hydrothermal alteration accompanying widespread silicification and quartz veining on western Hurd Peninsula. A mid-to late Cretaceous age for metasomatic disturbance agrees with field relations which indicate that the hydrothermal activity preceded or was coeval with the mid- to late Cretaceous period of volcanism on Livingston Island. Hence the hydrothermal rocks are not related to the Eocene Barnard Point pluton, as previously suggested.

Item Type: Publication - Article
Digital Object Identifier (DOI):
Programmes: BAS Programmes > Pre 2000 programme
ISSN: 0954-1020
Additional Keywords: accretionary complex, rubidium-strontium dating, hydrothermal alteration
NORA Subject Terms: Earth Sciences
Date made live: 21 Mar 2017 09:55 +0 (UTC)

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