Fluid inclusion evidence for subsurface phase separation and variable fluid mixing regimes beneath the deep-sea PACMANUS hydrothermal field, Manus Basin back arc rift, Papua New Guinea
Vanko, David A.
Yeats, Christopher J.
Scott, Steven D.
MetadataShow full item record
Altered volcanic rocks were cored from over 350 m below the seafloor at the Papua New Guinea-Australia-Canada Manus Basin Hydrothermal Field (PACMANUS) deep-sea hydrothermal field, in the eastern Manus back arc basin. Fluid inclusions in anhydrite veins reveal phase separation and fluid mixing beneath the seafloor. The anhydrite precipitated from high-temperature fluids (150–385°C). At Roman Ruins, a site of active high-temperature venting (220–276°C, measured by submersible), the fluid inclusion thermal depth profile is uniform and high temperature (242–368°C). At Snowcap, a site of warm water effusion (6–65°C), the fluid inclusions indicate high temperatures at depth (270–385°C) but both low and high temperatures in the shallower section. This indicates a flow regime dominated by vertical advection and shallow entrainment and mixing with cool seawater. Inclusions at Snowcap exhibit extreme salinity variations due to phase separation at temperatures above 350°C. Fluids contain Na, Cl, Fe, Zn, Mg, and Ba and a minor gas component such as CO2 or CH4. Most inclusions at Roman Ruins exhibit salinities that fall within the range of those observed at modern active vent sites along the mid-ocean ridge system. Fluid inclusion temperatures support a hypothesis, developed previously from Sr-isotopic analysis, that the subseafloor at Snowcap is characterized by mixing between deep-sourced hot hydrothermal fluids and cold seawater-like fluid. Both heating of seawater and cooling of upwelling hydrothermal fluids can be recognized by combining isotopic and fluid inclusion data. In contrast to Snowcap, the regime at Roman Ruins is less varied, with uniformly high-temperature upwelling fluids that have hydrothermally dominated Sr-isotopic ratios.
Author Posting. © American Geophysical Union, 2004. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 109 (2004): B03201, doi:10.1029/2003JB002579.
Suggested CitationJournal of Geophysical Research 109 (2004): B03201
Showing items related by title, author, creator and subject.
Wave scattering from cylindrical fluid inclusions in an elastic medium and determination of effective medium properties Laible, Henry A. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1995-09)The goal of this thesis is to be able to predict acoustic wave speeds in sea ice with known concentrations of inhomogeneities. To accomplish this, ice is modeled as a solid in which cylindrical fluid brine channels are ...
Klein, Frieder; Grozeva, Niya G.; Seewald, Jeffrey S. (National Academy of Sciences, 2019-09-03)The conditions of methane (CH4) formation in olivine-hosted secondary fluid inclusions and their prevalence in peridotite and gabbroic rocks from a wide range of geological settings were assessed using confocal Raman ...
Wanless, V. Dorsey; Shaw, Alison M.; Behn, Mark D.; Soule, Samuel A.; Escartin, Javier E.; Hamelin, Cedric (John Wiley & Sons, 2015-01-20)Here we present volatile, major, and trace element concentrations of 64 olivine-hosted melt inclusions from the Lucky Strike segment on the mid-Atlantic ridge. Lucky Strike is one of two locations where a crustal melt lens ...