Antarctic Science



Age and tectonic significance of the Lassiter Coast Intrusive Suite, Eastern Ellsworth Land, Antarctic Peninsula


M.J. FLOWERDEW a1a2c1, I.L. MILLAR a1a2, A.P.M. VAUGHAN a2 and R.J. PANKHURST a1
a1 NERC Isotope Geosciences Laboratory, Kingsley Dunham Centre, Keyworth, Nottingham NG12 5GG, UK
a2 British Antarctic Survey, NERC, High Cross, Madingley Road, Cambridge CB3 0ET, UK

Article author query
flowerdew mj   [PubMed][Google Scholar] 
millar il   [PubMed][Google Scholar] 
vaughan ap   [PubMed][Google Scholar] 
pankhurst rj   [PubMed][Google Scholar] 

Abstract

Depleted mantle model ages derived from granitoids of the Lassiter Coast Intrusive Suite, sampled over a wide geographical area in eastern Ellsworth Land, Antarctica, cluster between 1000 Ma and 1200 Ma and suggest involvement of Proterozoic crust in the petrogenesis of the suite. Ion-microprobe U–Pb zircon analyses from a small intrusion at Mount Harry, situated at the English Coast, yield a concordant age of 105.2 ± 1.1 Ma, consistent with published ages from other parts of the Lassiter Coast Intrusive Suite. Significant variation in the Sr and Nd isotope composition of the granitoids, along the extrapolation of the Eastern Palmer Land Shear Zone (a proposed terrane boundary) located close to the English Coast, is not evident. However, the isotope signature at the English Coast is more homogeneous than the Lassiter Coast; this variation may relate to geographical proximity to the Pacific margin during intrusion, may reflect subtle changes in basement with a broadly similar character across the proposed terrane boundary, or suggest that any major fault structure is located further to the north, with implications for the kinematics of regional mid-Cretaceous transpression.

(Received December 23 2004)
(Accepted May 3 2005)


Key Words: absolute age; English Coast; granite; Nd isotopes.

Correspondence:
c1 mf@bas.ac.uk


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