Dataset: Keratoisis Radiocarbon Dates

Name: Radiocarbon dates on calcite and organic material (gorgonin) in bamboo coral skeletons Keratoisis (Bamboo Coral Boron Isotopes project)
Published: 2014-12-17
Keywords: oceans

Cite This Dataset

Spatial Extent: N:44.25 E:-58.03 S:30.733 W:-79.433

Project:

Calibration and application of the boron isotope seawater-pH indicator in deep-water corals (Bamboo Coral Boron Isotopes)

Principal Investigator:

Dr Baerbel Hoenisch (Lamont-Doherty Earth Observatory, LDEO)

Contact:

Jesse Farmer (Lamont-Doherty Earth Observatory, LDEO)

BCO-DMO Data Manager:

Stephen R. Gegg (Woods Hole Oceanographic Institution, WHOI BCO-DMO)

Version:

17 December 2014

Version Date:

2014-12-17

Validated:

Yes

Current State:

Final no updates expected

Radiocarbon dates on calcite and organic material (gorgonin) in bamboo coral skeletons Keratoisis (Bamboo Coral Boron Isotopes project)

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Description

Radiocarbon dates on calcite and organic material (gorgonin) in bamboo coral skeletons

Related References:
Farmer, J.R., Hönisch, B., Robinson, L.F. and Hill, T.M. (2015) Effects of seawater-pH and biomineralization on the boron isotopic composition of deep-sea bamboo corals. In revision, Geochim. Cosmochim. Acta.

Sherwood, O.A., Edinger, E.N., Guilderson, T.P., Ghaleb, B., Risk, M.J. and Scott, D.B. (2008). Late Holocene radiocarbon variability in Northwest Atlantic slope waters. Earth Planet. Sci. Lett. 275, 146-153, doi:10.1016/j.epsl.2008.08.019.

Methods & Sampling

Sampling and Analytical Methodology:
All radiocarbon dates were obtained at the National Ocean Sciences Accelerator Mass Spectrometry facility (NOSAMS). Prior to sample submission, 3 to 5 mg of powdered calcite was cleaned of organic material following the oxidative procedure given in Farmer et al. (2015). Clean calcite powders were submitted to NOSAMS and leached with 200 µL of 0.1N HCl under sonication immediately prior to hydrolysis to remove any adsorbed modern CO₂. Approximately 10-20% of the sample mass was removed by the HCl leach. Gorgonin samples were prepared following Sherwood et al. (2008): decalcified nodes were separated with tweezers and a scalpel into individual gorgonin units, comprising 3 to >10 gorgonin layers where distinguishable. Approximately 2 to 3 mg of gorgonin was subsampled from larger units, soaked in 5% HCl for 48 hours to remove any residual carbonate, rinsed in deionized water and dried prior to submission to NOSAMS.

Full methodology, equations, and discussion of instrumental precision are available from the NOSAMS website: http://www.whoi.edu/nosams/

Data Processing Description

Data Processing:
Fraction Modern (Fm) = ((¹⁴C /¹²C_sample - ¹⁴C /¹²C_blank)/(¹⁴C /¹²C_reference - ¹⁴C /¹²C_blank))* ((1-25/1000)/(1+δ¹³C/1000))^2;

The reference is 95% of the radiocarbon concentration of NBS Oxalic Acid I (in 1950 AD) normalized to δ¹³C_VPDB=-19‰.

Conventional ¹⁴C age (in ¹⁴C years before 1950) = -8033*ln(Fm)

δ¹³C (‰) = (((¹³C/¹²C_sample)/(¹³C/¹²C_standard))-1)*1000; The standard is Vienna Pee Dee Belemnite (VPDB)

BCO-DMO Processing Notes
- Generated from original file: "DATASET-14C.xlsx" contributed by Jesse Farmer
- Parameter names edited to conform to BCO-DMO naming convention found at Choosing Parameter Name
- Lat/Lon sampling locations added from locations dataset to allow plotting in MapServer
- "nd" (no data) added to blank cells

Data Files

File
BC_14C.csv (Comma Separated Values (.csv), 4.65 KB) MD5:72db3cd6cd871272fa4537a4acea769f Primary data file for dataset ID 542953

More Information about this dataset

Funding Sources

Funding Source	Award Number
NSF Division of Ocean Sciences	OCE-1041133

Deployments

Deployment	Synonyms	Start Date	Platform	Investigator
BambooCoral_Hoenisch		1879-01-01	shoreside BAMBOO CORAL	Dr Baerbel Hoenisch (Principal Investigator)	data info

Instruments

Accelerator Mass Spectrometer

Supplied Name: AMS - National Ocean Sciences Accelerator Mass Spectrometry facility

Supplied Description:

All radiocarbon dates were obtained at the National Ocean Sciences Accelerator Mass Spectrometry facility (NOSAMS).

Full methodology, equations, and discussion of instrumental precision are available from the NOSAMS website: http://www.whoi.edu/nosams/

Instrument Type

Generic Name: Accelerator Mass Spectrometer

Acronym: AMS

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/LAB17/

Generic Description:

An AMS measures "long-lived radionuclides that occur naturally in our environment. AMS uses a particle accelerator in conjunction with ion sources, large magnets, and detectors to separate out interferences and count single atoms in the presence of 1x1015 (a thousand million million) stable atoms, measuring the mass-to-charge ratio of the products of sample molecule disassociation, atom ionization and ion acceleration." AMS permits ultra low-level measurement of compound concentrations and isotope ratios that traditional alpha-spectrometry cannot provide. More from Purdue University: http://www.physics.purdue.edu/primelab/introduction/ams.html

Parameters

Date and time formats are described in python strftime() syntax.

Supplied Name	Supplied description	Supplied Units	Standard Name
Accession_Number	Accession Number	text	accession_number
Age_Err_14C	Conventional 14C age error	14C years	C14_age_err
Conventional_14C_Age	Conventional 14C age (in 14C years before 1950) = -8033*ln(Fm	14C years	C14_age
Coral	Speciman Identifier	text	sample
Delta13C	13C (‰) = (((13C/12Csample)/( 13C/12Cstandard))-1)*1000; The standard is Vienna Pee Dee Belemnite (VPDB)	‰	delta13C
Depth	Length scale for sample either relative to the outside of the coral (distal surface)	mm	length
Depth_Error	Depth Error	mm	std_err
Fm_Err	Fraction Modern Error	‰	no_bcodmo_term
Fraction_Modern	Fraction Modern (Fm) = ((14C /12Csample - 14C /12Cblank)/( 14C /12Creference - 14C /12Cblank))* ((1-25/1000)/(1+δ13C/1000))^2	‰	no_bcodmo_term
Lat	Sample Latitude Location (South is negative)	decimal degrees	lat
Lon	Sample Longitude Location (West is negative)	decimal degrees	lon
Sample	Sample	text	sample_type
Type	Sample Type	text	sample_type

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Database

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Dataset: Keratoisis Radiocarbon Dates