# Lake Chichancanab Terminal Classic Droughts Gypsum Hydration Water Isotopes 
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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/24476 
#       Description: NOAA Landing Page
# Online_Resource: https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/yucatan/chichancanab2018gypsum.txt
#       Description: NOAA location of the template
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# Original_Source_URL:  
#       Description:
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# Description/Documentation lines begin with #
# Data lines have no #
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# Archive: Paleolimnology
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# Dataset DOI: 
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# Parameter_Keywords: oxygen isotopes, hydrogen isotopes
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# Contribution_Date
#    Date: 2018-08-02
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# File_Last_Modified_Date
#    Date: 2018-08-02
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# Title
#    Study_Name: Lake Chichancanab Terminal Classic Droughts Gypsum Hydration Water Isotopes 
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# Investigators
#      Investigators: Evans, N.P.; Bauska, T.K.; Gázquez-Sánchez, F.; Brenner, M.; Curtis, J.H.; Hodell, D.A.
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# Description_Notes_and_Keywords
#        Description: Sediment oxygen (d17O, d18O) and hydrogen (dD) isotopes from Lake Chichancanab, Yucatan, Mexico, for 602-1092 CE. 
#         Provided Keywords: Terminal Class Drought, Maya Civilization, triple oxygen isotopes, hydrogen isotopes, gypsum hydration water
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# Publication
# Authors: Nicholas P. Evans, Thomas K. Bauska, Fernando Gázquez-Sánchez, Mark Brenner, Jason H. Curtis, David A. Hodell 
# Published_Date_or_Year: 2018-08-03
# Published_Title: Quantification of drought during the collapse of the classic Maya civilization 
# Journal_Name: Science
# Volume: 361
# Edition: 
# Issue: 6401
# Pages: 498-501
# Report Number: 
# DOI: 10.1126/science.aas9871
# Online_Resource: http://science.sciencemag.org/content/361/6401/498
# Full_Citation: 
# Abstract: The demise of Lowland Classic Maya civilization during the Terminal Classic Period (~800 to 1000 CE) is a well-cited example of how past climate may have affected ancient societies. Attempts to estimate the magnitude of hydrologic change, however, have met with equivocal success because of the qualitative and indirect nature of available climate proxy data. We reconstructed the past isotopic composition (d18O, dD, 17O-excess, and d-excess) of water in Lake Chichancanab, Mexico, using a technique that involves isotopic analysis of the structurally bound water in sedimentary gypsum, which was deposited under drought conditions. The triple oxygen and hydrogen isotope data provide a direct measure of past changes in lake hydrology. We modeled the data and conclude that annual precipitation decreased between 41 and 54% (with intervals of up to 70% rainfall reduction during peak drought conditions) and that relative humidity declined by 2 to 7% compared to present-day conditions.
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# Funding_Agency
#    Funding_Agency_Name: European Research Council under the European Union's Seventh Framework Program (FP/2007-2013)
#    Grant: ERC grant agreement 339694 (Water Isotopes of Hydrated Minerals) 
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# Site Information
# Site_Name: Lake Chichancanab 
# Location: North America>Mexico
# Country: Mexico
# Northernmost_Latitude: 19.855
# Southernmost_Latitude: 19.855
# Easternmost_Longitude: -88.763
# Westernmost_Longitude: -88.763
# Elevation: 
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# Data_Collection
#   Collection_Name: Chichancanab2018GypsumIso
#   First_Year: 602
#   Last_Year: 1092
#   Time_Unit: CE
#   Core_Length: 
#   Notes: 
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# Chronology_Information 
# Chronology: 
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# Radiocarbon ages for core CH1 7-III-04 were obtained by Hodell et al. 2005.  Here we provided the depth-age model output with error.  
# We estimated calendar ages with 95% confidence intervals using the Bayesian Age-Depth Modeling software "BACON" in R. 
# Derived age-depth error 95% confidence was normalized to the best-fit line to produce age-depth errors for the Chichancanab density record.	
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# Variables
# Data variables follow that are preceded by "##" in columns one and two.
# Variables list, one per line, shortname-tab-longname components (9 components: what, material, error, units, seasonality, archive, detail, method, C or N for Character or Numeric data)
## core	Sample name,,,,,,,,C,
## depth_cm	Depth,,,cm,,,,,C,
## age_CE	Age,,,year Common Era,,,,,N,
## delta_17O_ghw	delta 17O,gypsum,,per mil VSMOW,,paleolimnology,,Cavitity Ring-down Spectroscopy,N, d17O of Gypsum Hydration Water
## delta_18O_ghw	delta 18O,gypsum,,per mil VSMOW,,paleolimnology,,Cavitity Ring-down Spectroscopy,N, d18O of Gypsum Hydration Water
## delta_D_ghw	delta D,gypsum,,per mil VSMOW,,paleolimnology,,Cavitity Ring-down Spectroscopy,N, dD of Gypsum Hydration Water
## delta_17O_mw	delta 17O,,,per mil VSMOW,,paleolimnology,,,N, d17O of calculated mother water
## delta_18O_mw	delta 18O,,,per mil VSMOW,,paleolimnology,,,N, d18O of calculated mother water
## delta_D_mw	delta D,,,per mil VSMOW,,paleolimnology,,,N, dD of calculated mother water
## O17_excess_mw	17O-excess,,,per meg (VSMOW-SLAP normalitization),,paleolimnology,,(VSMOW-SLAP normalitization),N, O17-excess of calculated mother water
## d_excess_mw	d-excess,,,per mil VSMOW,,paleolimnology,,,N,d-excess of calculated mother water
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# Data
# Data lines follow (have no #)
# Data line format - tab-delimited text, variable short name as header
# Missing Value: 
core	depth_cm	age_CE	delta_17O_ghw	delta_18O_ghw	delta_D_ghw	delta_17O_mw	delta_18O_mw	delta_D_mw	O17_excess_mw	d_excess_mw
CHI 07-III-04  128.0-128.5 cm	128	1092	4.08	7.81	-2.66	2.24	4.33	17.0	-46	-17.7
CHI 07-III-04  129.0-129.5 cm	129	1085	3.83	7.33	-4.58	1.99	3.85	15.0	-38	-15.8
CHI 07-III-04  130.5-131.0 cm	130.5	1073	3.70	7.08	-5.86	1.87	3.60	13.7	-33	-15.1
CHI 07-III-04  131.0-131.5 cm	131	1069	3.91	7.46	-4.57	2.07	3.99	15.0	-31	-16.9
CHI 07-III-04  132.0-132.5 cm	132	1059	4.21	8.04	-1.35	2.37	4.57	18.3	-35	-18.2
CHI 07-III-04  133.0-133.5 cm	133	1050	3.73	7.12	-3.90	1.90	3.65	15.7	-30	-13.5
CHI 07-III-04  133.5-134.0 cm	133.5	1046	3.84	7.34	-4.41	2.01	3.87	15.2	-34	-15.8
CHI 07-III-04  134.0-134.5 cm	134	1041	4.11	7.85	-2.99	2.27	4.37	16.6	-31	-18.3
CHI 07-III-04  135.5-136.0 cm	135.5	1026	3.90	7.45	-3.74	2.06	3.98	15.9	-36	-15.9
CHI 07-III-04  136.0-136.5 cm	136.5	1013	4.01	7.65	-2.63	2.17	4.17	17.0	-31	-16.4
CHI 07-III-04  136.5-137.0 cm	137.5	1000	4.04	7.71	-3.20	2.20	4.24	16.4	-36	-17.5
CHI 07-III-04  137.0-137.5 cm	138	993	3.83	7.34	-4.14	2.00	3.87	15.5	-42	-15.5
CHI 07-III-04  139.5-140.0 cm	139.5	973	3.77	7.21	-4.19	1.93	3.73	15.4	-40	-14.5
CHI 07-III-04  140.0-140.5 cm	140	967	3.89	7.45	-3.27	2.05	3.98	16.3	-47	-15.5
CHI 07-III-04  140.5-141.5 cm 	140.5	960	3.83	7.31	-4.04	1.99	3.84	15.6	-32	-15.1
CHI 07-III-04  142.0-142.5 cm	142	939	4.36	8.33	-1.27	2.52	4.85	18.4	-36	-20.4
CHI 07-III-04  148.0-148.5 cm	148	849	3.95	7.54	-3.18	2.11	4.07	16.4	-33	-16.1
CHI 07-III-04  149.0-149.5 cm	149	833	4.00	7.65	-3.72	2.16	4.18	15.9	-43	-17.5
CHI 07-III-04  150.0-151.0 cm	150	817	4.21	8.04	-1.92	2.37	4.56	17.7	-36	-18.8
CHI 07-III-04  151.0-151.5 cm	151	801	4.13	7.89	-2.62	2.29	4.42	17.0	-36	-18.3
CHI 07-III-04  151.5-152.0 cm	151.5	793	4.31	8.24	-1.40	2.47	4.77	18.2	-43	-19.9
CHI 07-III-04  153.0-153.5 cm	153	768	3.75	7.17	-3.70	1.91	3.69	15.9	-33	-13.6
CHI 07-III-04  153.5-154.0 cm	153.5	760	4.05	7.74	-2.34	2.22	4.26	17.3	-32	-16.8
CHI 07-III-04  154.0-154.5 cm	154	752	4.28	8.18	-0.88	2.44	4.70	18.8	-35	-18.8
CHI 07-III-04  154.5-155.0 cm	154.5	744	3.98	7.60	-3.69	2.14	4.12	15.9	-33	-17.1
CHI 07-III-04  154.5-155.0 cm	154.5	744	4.11	7.84	-3.01	2.27	4.37	16.6	-32	-18.3
CHI 07-III-04  155.0-155.5 cm	155	736	4.12	7.89	-2.76	2.28	4.42	16.9	-45	-18.5
CHI 07-III-04  155.5-156.0 cm	155.5	728	3.90	7.48	-3.44	2.07	4.01	16.2	-45	-15.9
CHI 07-III-04  156.0-156.5 cm	156	720	4.08	7.81	-3.47	2.24	4.34	16.1	-48	-18.6
CHI 07-III-04  166.0-166.5 cm	166	611	3.84	7.32	-4.48	2.00	3.85	15.1	-26	-15.7
CHI 07-III-04  167.0-167.5 cm	167	605	4.15	7.93	-1.91	2.31	4.46	17.7	-43	-17.9
CHI 07-III-04  167.5-168.0 cm	167.5	602	3.86	7.34	-4.59	2.02	3.86	15.0	-19	-15.9