Evidence for Palaeozoic magmatism recorded in the Late Neoproterozoic Marlborough ophiolite, New England Fold Belt, central Queensland

Authors
Citation
Mc. Bruce et Y. Niu, Evidence for Palaeozoic magmatism recorded in the Late Neoproterozoic Marlborough ophiolite, New England Fold Belt, central Queensland, AUST J EART, 47(6), 2000, pp. 1065-1076
Citations number
47
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Earth Sciences
Journal title
AUSTRALIAN JOURNAL OF EARTH SCIENCES
ISSN journal
0812-0099 → ACNP
Volume
47
Issue
6
Year of publication
2000
Pages
1065 - 1076
Database
ISI
SICI code
0812-0099(200012)47:6<1065:EFPMRI>2.0.ZU;2-#
Abstract
The ultramafic-mafic complex in the Marlborough terrane of the northern New England Fold Belt is dominated by members of a Neoproterozoic (ca 560 Ma) ophiolite (V1). The ophiolite has been intruded by the products of three Pa laeozoic tectonomagmatic episodes (V2, V3 and V4). The V2 magmatic episode is represented by tholeiitic and calc-alkaline basalts and gabbros of islan d-arc affinities. Sm/Nd isotopes give a whole-rock isochron age of 380 +/- 19 Ma (2 sigma) to this episode, some 180 million years younger than the V1 ophiolitic rocks. The V3 magmatic episode includes tholeiitic and alkali b asalts with enriched geochemical signatures characteristic of intraplate vo lcanism. A whole-rock Sm/Nd isochron age of 293 +/- 35 Ma is obtained for t his event. A fourth magmatic event (V4) is represented by basaltic andesite s and siliceous intrusives with geochemical features similar to modern adak ites. This event has its type locality in the Percy Isles. These data provi de tectonic and geochronological constraints for the previously enigmatic M arlborough terrane and as such contribute to the ever-evolving understandin g of New England Fold Belt development.