The Vanuatu Australia Vents Expedition (VAVE) to the Coriolis Troughs in southern Vanuatu during September 2001 aboard the RV Franklin discovered a new hydrothermall vent field-herein informally named Nifonea-and recent alkallic volcanic activity. The Nifonea field in the central Vate Trough was located by coincident light transmission and CH4 anomalies in a hydrothermal plume of ∼60 km2 extent, best developed between 1600 and 1750 m depth at ∼150 m above the seafloor. Extensive hydrothermal fauna and yellow-brown crusts and mounds cover an area of ∼1 km2. Very fresh, glassy, variably vesicular, sparsely phyric and aphyric basalt, trachybasalt, and basaltic trachyandesite (with ∼5-6 wt% combined alkalies at ∼ 51%-53% SiO2 and enriched light rare earth elements, Nb, and Zr) samples were dredged from youthful curtain, tube, and sheet flows, plus iron oxyhydroxide deposits. The alkalic composition of lavas in this tectonic setting is unique and attributed to thin ocean crust being developed in an incipient rifting phase involving a relatively low percentage of source-mantle melting. The Coriolis Troughs are among Earth's most youthful backarc basins and thus provide valuable insights to incipient rifting and hydrothermal processes. © 2005 Geological Society of America.

Item Type:	Refereed Article
Research Division:	Earth Sciences
Research Group:	Geology
Research Field:	Igneous and Metamorphic Petrology
Objective Division:	Expanding Knowledge
Objective Group:	Expanding Knowledge
Objective Field:	Expanding Knowledge in the Earth Sciences
UTAS Author:	Sharpe, R (Dr Robina Sharpe)
ID Code:	39073
Year Published:	2005
Web of Science® Times Cited:	15
Deposited By:	Centre for Ore Deposit Research - CODES CoE
Deposited On:	2005-08-01
Last Modified:	2006-05-05
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