Open AccessHelium systematics of cold seep fluids at Monterey Bay, California, USA: Temporal variations and mantle contributions
Author(s) -
Füri E.,
Hilton D. R.,
Brown K. M.,
Tryon M. D.
Publication year - 2009
Publication title -
geochemistry, geophysics, geosystems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.928
H-Index - 136
ISSN - 1525-2027
DOI - 10.1029/2009gc002557
Subject(s) - geology , mantle (geology) , petroleum seep , bay , cold seep , isotopes of helium , oceanography , methane , geophysics , helium , ecology , physics , biology , atomic physics
We report helium isotope ratios ( 3 He/ 4 He) as well as helium and neon abundance results for submarine cold seep fluids from Extrovert Cliff in Monterey Bay, California. Samples were collected in copper tubing attached to submarine flux meters operating in continuous pumping mode. Following instrumentation recovery, the tubing was sectioned to produce for the first time a high‐resolution time series of dissolved He and Ne variations over a time span of several days. Noble gas concentrations are variable and appear affected by interaction with a hydrocarbon phase within the aquifer. However, it is still possible to resolve the He signal into components associated with air equilibration, excess air entrainment, and terrigenic fluxes (both crustal and mantle‐derived). The mantle He contribution reaches ∼25–30% in some samples (up to 2.3 R A , where R A = air 3 He/ 4 He). Our quasi‐continuous He‐Ne record shows remarkable fluctuations over time scales of only a few hours and reflects the combined effects of gas stripping by hydrocarbons and an episodic input of mantle‐derived fluids.