thumbnail

New Rb-Sr mineral ages temporally link plume events with accretion at the margin of Gondwana

Open-File Report 2007-1047-SRP-012

By:
, ,
DOI: 10.3133/ofr20071047SRP012

Links

Abstract

Five of six Rb-Sr muscovite mineral isochron ages from the Scotia Metamorphic Complex of the South Orkney Islands, West Antarctica, average 190 ± 4 Ma. The muscovite ages are interpreted to date foliation-formation and thus also accretion and subduction at the Gondwana margin. Coincident picrite and ferropicrite magmatism, indicative of melts from deep-seated depleted mantle, permits a causative link between accretion and the arrival of the Karoo – Ferrar – Chon Aike mantle plume in the Early Jurassic. Three biotite Rb-Sr mineral isochron ages are consistently younger and average 176 ± 5 Ma. The biotite ages may record post-metamorphic cooling or more likely retrogressive metamorphic effects during uplift.

Geospatial Extents

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
New Rb-Sr mineral ages temporally link plume events with accretion at the margin of Gondwana
Series title:
Open-File Report
Series number:
2007-1047-SRP-012
DOI:
10.3133/ofr20071047SRP012
Year Published:
2007
Language:
English
Publisher:
U.S. Geological Survey
Publisher location:
Reston, VA
Description:
4 p.
Larger Work Type:
Report
Larger Work Subtype:
USGS Numbered Series
Other Geospatial:
Antarctica
Online Only (Y/N):
N