Unique event plumes from a 2008 eruption on the Northeast Lau Spreading Center

Abstract

[1] The creation of ocean crust by lava eruptions is a fundamental Earth process, involving immediate and immense transfers of heat and chemicals from crust to ocean. This transfer creates event plumes ("megaplumes"), massive ellipsoidal eddies with distinctive and consistent chemical signatures. Here we report the discovery of unique event plumes associated with a 2008 eruption on the Northeast Lau Spreading Center. Instead of a large plume hundreds of meters thick, we detected at least eight individual plumes, each ∼50 m thick and apparently only 1-3 km in diameter, yet still rising 200-1000 m above the eruption site. Low and uniform 3 He/heat (0.041 × 10 −17 mol/J) and dissolved Mn/heat (0.04 nmol/J) ratios in water samples were diagnostic of event plumes. High H 2 concentrations (up to 9123 nM) and basalt shards confirmed extensive interactions between molten lava and event plume source fluids. Remote vehicle observations in 2009 mapped a new, small (1.5-5.8 × 10 6 m 3 ) lava flow. Our results suggest that event plumes are more variable, and thus perhaps more common, than previously recognized. Small event plumes may be preferentially associated with small or sheet-flow eruptions, and massive event plumes with slowly extruding pillow mounds 25-75 m thick. Despite this correlation, and high H 2 concentrations, existing theory and seafloor observations argue that cooling lava cannot transfer heat fast enough to create the buoyancy flux required Copyright 2011 by the American Geophysical Union 1 of 21 for event plumes. The creation of event plumes under a broad range of eruption conditions provides new constraints for any theory of their formation.

Understanding a submarine eruption through time series hydrothermal plume sampling of dissolved and particulate constituents: West Mata, 2008–2012

“…The real‐time characterization of H 2 and CH 4 in hydrothermal plumes associated with seafloor eruptions is rare, due to the rapid consumption of many of the volatiles as well as the short‐lived nature of eruption‐associated hydrothermal plumes [ Kadko et al ., ; de Angelis et al ., ; Lilley et al ., ; McLaughlin et al ., ; Kelley et al ., ; Resing et al ., ]. In particular, H 2 concentration data from young plumes are very limited [ Kelley et al ., ; McLaughlin , ; McLaughlin‐West et al ., ; Baker et al ., ]. A comprehensive hydrothermal plume data set (H 2 , CH 4 , and 3 He concentrations and heat anomalies) was obtained from the Gorda Ridge where a diking‐eruptive event generated event plumes in 1996 [ Kelley et al ., ].…”

“…Fluid samples from the hydrothermal plumes associated with these volcanic eruptions were analyzed for CH 4 , He, CO 2 , Fe, and Mn [ Resing et al ., ]. Even though important information on the composition of young hydrothermal plumes was collected during the NW Rota‐1 studies, processes that create hydrothermal plumes during volcanic eruptions are not yet fully understood [ Baker et al ., ; Lupton et al ., ; Palmer and Ernst , ]. Some of these processes include the role of conductive heat transfer from magma and lava to seawater, the input of magmatic gases to the hydrothermal plume, the role of rapid subseafloor and lava‐seawater interface reactions versus flushing of a “preformed” hydrothermal reservoir, and the potential for buried biomass to influence fluid chemistry.…”

“…Extensive water column investigations using a CTD with optical and chemical profiling capabilities and a water sampling rosette during the Northeast (NE) Lau Basin Cruise in November 2008 revealed exceptionally high H 2 concentrations and volcaniclastic shards at the neovolcanic zone of the southernmost segment of the Northeast Lau Spreading Center (NELSC) [ Baker et al ., ] and at the submarine volcano West Mata, 60 km NE of the NELSC [ Resing et al ., ]. These observations resulted in the Northeast Lau Basin Response Cruise (NELRC) in May 2009.…”

Hydrothermal Discharge During Submarine Eruptions: The Importance of Detection, Response, and New Technology

“…Hints of previously unsuspected crust-ocean interaction first appeared in the mid-1980s and early 1990s, when serendipitous observations and rapidresponse cruises began documenting eruptions that produced not only new lava but also massive transfers of heat, chemicals, and biota from the solid Earth to the deep ocean (e.g., see summaries by Baker, 1995;Lupton et al, 1999;Cowen et al, 2004;Baker et al, 2011).…”

Hydrothermal activity in the Northwest Lau Backarc Basin: Evidence from water column measurements

“…This combination of effects is thought to produce elevated mantle temperatures and vigorous mantle flow patterns in the Lau Basin. The rapid extension and elevated temperatures may result in enhanced magmatic and hydrothermal activity in the Lau Basin [German et al, 2006;Keller et al, 2008;Embley et al, 2009;Kim et al, 2009;Baker et al, 2011;Resing et al, 2011]. In this paper we examine whether the rapid extension accommodated by the NWLSC is expressed by elevated magmatic activity as identified by contemporaneous hydrothermal activity.…”