URLhttps://www.bco-dmo.org/dataset/661750
Download URLhttps://www.bco-dmo.org/dataset/661750/data/download
Media Typetext/tab-separated-values
CreatedOctober 14, 2016
ModifiedDecember 5, 2017
StateFinal no updates expected
Brief DescriptionPorewater methane concentrations from sediment cores collected on the Guaymas Basin Ridge flanks and the Sonora Margin in 2014

Acquisition Description

2 ml sediment samples were taken with cut-off syringes from freshly retrieved sediment cores, placed into 5 ml of 1 mM NaOH in 30 ml serum vials, and capped with thick rubber stoppers. Methane concentrations were measured in the laboratory of J.P. Chanton (Florida State University) according to a modified headspace technique (Magen et al. 2014). Methane isotopic composition was measured by gas chromatography coupled with mass spectrometry (Chanton and Liptay 2014).

References:
Magen, C., L.L. Lapham, J.W. Pohlman, K. Marshall, S.Bosman, M. Casso, and J.P. Chanton. 2014. A simple headspace equilibration method for measuring dissolved methane. Limnol. Oceanogr. Methods 12 637-650. doi:10.4319/lom.2014.12.637

Chanton, J., and K. Liptay. 2000. Seasonal variation in methane oxidation in a landfill cover soils as determined by an in-situ stable topic technique. Global Biogeochemical Cycles 14:51-60. doi:10.1029/1999GB900087

Processing Description

BCO-DMO Processing:
- created a column for core number;
- added lat, lon, and depth for each core from the metadata form;
- replaced "n.a." with "nd" (no data);
- modified parameter names to conform with BCO-DMO naming conventions.

Instruments

gas chromatography [Gas Chromatograph]
Details
Instance Description (gas chromatography)

Methane isotopic composition was measured by gas chromatography coupled with mass spectrometry (Chanton and Liptay 2014).

Instrument separating gases, volatile substances, or substances dissolved in a volatile solvent by transporting an inert gas through a column packed with a sorbent to a detector for assay. (from SeaDataNet, BODC)
mass spectrometry [Mass Spectrometer]
Details
Instance Description (mass spectrometry)

Methane isotopic composition was measured by gas chromatography coupled with mass spectrometry (Chanton and Liptay 2014).

General term for instruments used to measure the mass-to-charge ratio of ions; generally used to find the composition of a sample by generating a mass spectrum representing the masses of sample components.

Parameters

core [core_id]
Details
core

Core identifier

core number/identification, to be used with ice, rock and sediment cores

lat [latitude]
Details
lat
Latitude of sampling location; postive = north

latitude, in decimal degrees, North is positive, negative denotes South; Reported in some datasets as degrees, minutes

lon [longitude]
Details
lon
Longitude of sampling location; negative = west

longitude, in decimal degrees, East is positive, negative denotes West; Reported in some datsets as degrees, minutes

depth [depth_w]
Details
depth

Water depth at sampling location

water depth, in meters

core_sample [sample]
Details
core_sample

Identifier for the core sample

unique sample identification or number; any combination of alpha numeric characters; precise definition is file dependent

actual_depth [depth_core]
Details
actual_depth

Sample depth, within the core

depth in core; mid-point of interval sampled
methane_mM [CH4]
Details
methane_mM

Methane concentration

methane

methane_d13C [unknown]
Details
methane_d13C
Methane d13C signature
association with a community-wide standard parameter is not yet defined

Dataset Maintainers

NameAffiliationContact
Andreas P. TeskeUniversity of North Carolina at Chapel Hill (UNC-Chapel Hill)
Ivano AielloMoss Landing Marine Laboratories (MLML)
Ana Christina RaveloUniversity of California-Santa Cruz (UC Santa Cruz)
Andreas P. TeskeUniversity of North Carolina at Chapel Hill (UNC-Chapel Hill)
Shannon RauchWoods Hole Oceanographic Institution (WHOI BCO-DMO)

BCO-DMO Project Info

Project TitleRAPID proposal: Site characterization cruise to document the active and extensive subsurface biosphere in the Guaymas Basin
AcronymRAPID Guaymas Basin
URLhttps://www.bco-dmo.org/project/626087
CreatedNovember 5, 2015
ModifiedMarch 13, 2019
Project Description

Description from NSF project abstract:
The Guaymas Basin in the central Gulf of California is an active tectonic spreading center overlain with thick, organic-rich sediments. In contrast to typical deep-water, mid-ocean ridge spreading centers that have very focused magmatism and little or no sediment, magmatism in the Guaymas Basis is more broadly distributed. This broadly-distributed magmatism significantly expands the fraction of organic-rich sediments that may be subject to alteration by the magmatic heat and thus it greatly expands the range of environments that support hydrocarbon generation and microbial populations in the sediments. Recognition that magmatism is not confined to the spreading axis, but instead is distributed throughout Guaymas Basin, suggests that models for the natural sequestration of carbon, the formation of oceanic crust, and life in the subsurface in marginal rift basins should be reconsidered as this has implications for the long-term removal of atmospheric carbon dioxide (and hence potential climatic implications). The Principal Investigator of this RAPID proposal is a lead proponent on an International Ocean Discovery Program (IODP) proposal to study this system in depth through scientific ocean drilling. To properly plan this expensive IODP expedition, additional site characterization gained from sediment sampling and seismic data is required. This proposal requests funds for the Principal Investigator to participate on an already planned site survey cruise aboard the Mexican Research Vessel (RV) El Puma. The results from this cruise will provide valuable data, at an exceptionally low investment, to guide decisions about potential future scientific drilling in the Guaymas Basin.

This RAPID proposal requests funds for the Principal Investigator to participate on a Mexican site survey cruise in October 2014 on RV El Puma to collect five-meter gravity cores of an extensive sediment transect across the Guaymas Basin and to integrate sequencing-based microbial community analyses of subsurface bacteria and archaea with biogechemical characterizations of these subsurface sediments. Gravity coring and microbial community analysis will target cold non-hydrothermal sediments as well as off-axis hydrothermally-influenced sediments. The gravity coring campaign and the geochemistry/microbiology studies are coordinated with heatflow measurements and extensive 2D seismic analysis and high-resolution 3D seismic mapping by other planned Mexican and German cruises. This multi-pronged strategy will deliver the additional data and complete the site characterizations that are required to properly plan a potential IODP drilling expedition by the JOIDES Resolution.

Project Maintainers
NameAffiliationRoleContact
Andreas P. TeskeUniversity of North Carolina at Chapel Hill (UNC-Chapel Hill)Principal Investigator
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