# McMurdo Region, Antarctica Miocene-Quaternary Carbonate Cement Isotope Data 
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#                World Data Service for Paleoclimatology, Boulder 
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#                     NOAA Paleoclimatology Program 
#             National Centers for Environmental Information (NCEI)
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# NOTE: Please cite Publication, and Online_Resource and date accessed when using these data. 
# If there is no publication information, please cite Investigators, Title, and Online_Resource and date accessed. 
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# Online_Resource: https://www.ncdc.noaa.gov/paleo/study/28132 
#       Description: NOAA Landing Page
# Online_Resource: https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/antarctica/dvdp-11iso.txt
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# Original_Source_URL:  
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# Description/Documentation lines begin with #
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# Archive: Paleolimnology
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# Dataset DOI: 
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# Parameter_Keywords: carbon isotopes, oxygen isotopes
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# Contribution_Date
#	Date: 2019-10-31
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# File_Last_Modified_Date
#	Date: 2019-10-31
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# Title
#	Study_Name: McMurdo Region, Antarctica Miocene-Quaternary Carbonate Cement Isotope Data 
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# Investigators
#	Investigators: Yang, M.; Frank, T.D.; Fielding, C.R.
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# Description_Notes_and_Keywords
#	Description: Stable isotope (d13C and d18O) data of carbonate cement from drill holes in the McMurdo Sound region, Antarctica, Miocene to Quaternary age. 
#	Data are from Dry Valley Drilling Project-10 and -11 cores, and ANDRILL McMurdo Ice Shelf-1B core. 
#	Provided keywords: aragonite cement, cryogenic brine, Quaternary glaciation, Antarctica
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# Publication 
#	Authors: Mingyu Yang, Tracy D. Frank, Christopher R. Fielding
#	Published_Date_or_Year: 2019-10-23     
#	Published_Title: Intergranular aragonite cement as evidence for widespread cryogenic brine formation during Quaternary glaciation in the McMurdo Sound region, Antarctica
#	Journal_Name: Geochimica et Cosmochimica Acta
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#	DOI: 10.1016/j.gca.2019.10.027
#	Online_Resource: https://www.sciencedirect.com/science/article/pii/S0016703719306817
#	Full_Citation: 
#	Abstract: Briny groundwater is present below the extremely cold and dry surface of the McMurdo Dry Valleys and below the seafloor of the adjacent McMurdo Sound in Antarctica. The lack of reliable groundwater samples in the region, however, has long limited understanding of its origin, nature, and spatial distribution. In this regard, intergranular carbonate cements, widespread in subsurface Cenozoic strata and recently recognized as brine precipitates, provide an indirect means of solving these issues. This study examines the petrography and isotope geochemistry of intergranular aragonite cement phases that occur in subsurface Pliocene-Quaternary sedimentary sections that formed in the lower Taylor Valley (cores DVDP-10, -11) and in offshore McMurdo Sound (core AND-1B). Aragonite cement in the coastal Taylor Valley sections is characterized by very low d18O values (-26.9 to -19.4 permil VPDB) compared to values in the offshore section (-12.5 to -2.7 per mil VPDB). These differences are interpreted to reflect two settings for cryogenic brine formation, which produced isotopically distinct brines during Quaternary glaciation. In the coastal region, seawater-meltwater mixtures were isolated and cryogenically concentrated in an ice-dammed lake setting that formed in response to the expansion of the East and West Antarctic Ice Sheets into the lower Taylor Valley. In McMurdo Sound, cryogenic concentration of seawater occurred in a semi-isolated flexural trough that was deepened by lithospheric depression of volcanic edifices and the expanded West Antarctic Ice Sheet. Aragonite cement phases serve as excellent proxies for tracing the extents of subsurface brine bodies along the continental margin of Antarctica. Given the propensity for cryogenic brine formation in glaciomarine settings, the likelihood of brine cements in rock records from other analogous high-latitude, cold settings must not be overlooked.
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# Funding_Agency 
#	Funding_Agency_Name: US National Science Foundation
#	Grant: PLR-1341390
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# Funding_Agency 
#	Funding_Agency_Name: Geological Society of America 
#	Grant: Student Research Grant 
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# Site_Information 
#	Site_Name: Dry Valley Drilling Project 11
#	Location: Antarctica
#	Country:  
#	Northernmost_Latitude: -77.58
# 	Southernmost_Latitude: -77.58
# 	Easternmost_Longitude: 163.42
# 	Westernmost_Longitude: 163.42
# 	Elevation: 2
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# Data_Collection   
#	Collection_Name: DVDP-11iso
#	Earliest_Year: 5000000
#	Most_Recent_Year: 11000
#	Time_Unit: Cal. Year BP
#	Core_Length: 328
#	Notes: 
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# Chronology_Information
#	Chronology: 
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# Variables 
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# Data variables follow are preceded by "##" in columns one and two.
# Data line variables format:  one per line, shortname-tab-variable components (what, material, error, units, seasonality, data type,detail, method, C or N for Character or Numeric data, free text) 
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## depth_m	depth, , , m, , , , ,N,
## cem_type	Cement type,,,,,,,,C,	
## morph	Morphology of carbonate cement,,,,,,,,C,	
## mineral	Mineralogy of carbonate cement,,,,,,,,C,	
## d13C	delta 13C, calcium carbonate, ±0.10 per mil, per mil VPDB, ,paleolimnology,,Stable isotope gas ratio mass spectrometer,N,Sandstone carbonate cement
## d18O	delta 18O, calcium carbonate, ±0.10 per mil, per mil VPDB, ,paleolimnology,,Stable isotope gas ratio mass spectrometer,N,Sandstone carbonate cement
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# Data:
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# Data line format - tab-delimited text, variable short name as header
# Missing Values:  
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depth_m	cem_type	morph	mineral	d13C	d18O
31.45	intergrnular cement	acicular	aragonite	0.2	-25.2
62.67	intergrnular cement	acicular	aragonite	-4.5	-26.9
76.70	intergrnular cement	acicular	aragonite	-2.7	-24.9
93.03	intergrnular cement	acicular	aragonite	-1.9	-25.5
253.55	intergrnular cement	microcrystalline 	calcite	-2.5	-24.0