Extensive hydrothermal activity in the NE Lau basin revealed by ROV dives

Friday, 19 December 2014
Robert W Embley1, Joseph A Resing2, Bradley Tebo3, Edward T Baker4, David A Butterfield5, Bill Chadwick6, Richard Davis3, Cornel E J de Ronde7, Marvin D Lilley8, John E Lupton9, Susan G Merle6, Kenneth Howard Rubin10, Timothy M Shank11, Sharon L Walker12, Richard J Arculus13, Andra M Bobbitt6, Nathaniel J Buck2, Fabio Caratori Tontini7, Peter V Crowhurst14, Edward Mitchell15, Eric J Olson8, Volker Ratmeyer16, Simon Richards17, Kevin K Roe2, Paula Kenner-Chavis18, Anabelle Martinez-Lyons11, Carolyn Sheehan3 and Roland Brian18, (1)NOAA Newport, Newport, OR, United States, (2)Joint Institute for the Study of the Atmosphere and Ocean, and NOAA/PMEL, Seattle, WA, United States, (3)Oregon Health & Science University, Portland, OR, United States, (4)Joint Institute for the Study of the Atmosphere and Ocean, Seattle, WA, United States, (5)University of Washington/NOAA/PMEL, Seattle, WA, United States, (6)Oregon State University, CIMRS, and NOAA/PMEL, Corvallis, OR, United States, (7)GNS Science-Institute of Geological and Nuclear Sciences Ltd, Lower Hutt, New Zealand, (8)Univ Washington, Seattle, WA, United States, (9)NOAA/PMEL, Newport, OR, United States, (10)Univ Hawaii, Honolulu, HI, United States, (11)WHOI, Woods Hole, MA, United States, (12)NOAA/PMEL, Seattle, WA, United States, (13)Australian National University, Canberra, Australia, (14)Nautilus Minerals Inc., Corinda, Australia, (15)Oregon State University, College of Pharmacy, Corvallis, OR, United States, (16)MARUM - University of Bremen, Bremen, Germany, (17)James Cook University, Earth & Oceans Group, College of Science, Technology & Engineering, Townsville, Australia, (18)NOAA, OER, Silver Spring, MD, United States
Dives with the QUEST 4000 ROV (Remotely Operated Vehicle) in September 2012 discovered nine hydrothermal sites in the arc and rear-arc region of the NE Lau Basin in 1150 m to 2630 m depth. These sites, originally detected by water column and seafloor surveys conducted in 2008-2011, include: (1) a paired sulfur-rich/black smoker field on the summit of a tectonically deformed magmatic arc volcano (Niua), (2) fracture-controlled black smoker venting on several small en echelon seamounts (north Matas) that lie between the magmatic arc and the backarc spreading center and (3) a magmatic degassing site on the summit of a dacite cone within a large (~12 km diameter) caldera volcano (Niuatahi). Dives at West Mata Seamount, which was undergoing strombolian volcanic activity and effusive rift-zone eruptions from 2008 to 2010, revealed a dormant volcanic phase in September 2012, with continued low-temperature diffuse venting. The high-temperature venting is likely driven by magmatic heat indicative of underlying partial melt zones and/or melt pockets distributed through the region. The occurrence of the youngest known boninite eruptions on the Mata volcanoes is consistent with subduction fluid flux melting extending into the rear-arc zone. Extension related to the transition from subduction to strike-slip motion of the northern Tonga Arc over the active Subduction-Transform Edge Propagator (STEP) fault probably contributes to the enhanced volcanism/hydrothermal activity in the NE Lau Basin. Chemosynthetic ecosystems at these sites range from mostly motile, lower diversity ecosystems at the eruptive/magmatically-degassing sites to higher diversity ecosystems with less mobile faunal components at the black-smoker systems. The wide range of fluid chemistry, water depth and geologic settings of the hydrothermal systems in this area provides an intriguing template to study the interaction of hydrothermal fluid chemistry, chemosynthetic habitats and their geologic underpinning within an arc/backarc setting.