Citation:

2007PA001527

Name: (Table 1) U and Th isotopic composition and 230Th ages of samples from the A1 and C1 corals of Legare Anchorage
Published: 2008
License: https://creativecommons.org/licenses/by/3.0/

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Abstract:

The 14C reservoir age of the surface ocean was determined for two Holocene periods (4908-4955 and 3008-3066 calendar (cal) B.P.) using U/Th-dated corals from Biscayne National Park, Florida, United States. We found that the average reservoir ages for these two time periods (294 ± 33 and 291 ± 27 years, respectively) were lower than the average value between A.D. 1600 and 1900 (390 ± 60 years) from corals. It appears that the surface ocean was closer to isotopic equilibrium with CO2 in the atmosphere during these two time periods than it was during recent times. Seasonal d18O measurements from the younger coral are similar to modern values, suggesting that mixing with open ocean waters was indeed occurring during this coral's lifetime. Likely explanations for the lower reservoir age include increased stratification of the surface ocean or increased D14C values of subsurface waters that mix into the surface. Our results imply that a more correct reservoir age correction for radiocarbon measurements of marine samples in this location from the time periods ~3040 and ~4930 cal years B.P. is ~292 ± 30 years, less than the canonical value of 404 ± 20 years.

Coverage:

Latitude: 25.483000 * Longitude: -80.142000

Date/Time Start: 1991-09-01T00:00:00 * Date/Time End: 1991-09-01T00:00:00

Minimum Elevation: -8.0 m * Maximum Elevation: -8.0 m

Event(s):

Legare_Anchorage * Latitude: 25.483000 * Longitude: -80.142000 * Date/Time: 1991-09-01T00:00:00 * Elevation: -8.0 m * Recovery: 1.19 m * Location: Florida shelf * Method/Device: Drilling/drill rig (DRILL) * Comment: two cores of fossil corals (Montastrea annularis), A1 62 cm and C1 119 cm

Comment:

AGE [ka BP] presents the corrected Th age before 2007.

Parameter(s):

#	Name	Short Name	Unit	Principal Investigator	Method/Device	Comment
1	Laboratory code/label	Lab label		Druffel, Ellen R M
2	Sample code/label	Sample label		Druffel, Ellen R M
3	Method comment	Method comm		Druffel, Ellen R M
4	Uranium-238	238U	mg/kg	Druffel, Ellen R M
5	Uranium-238, standard deviation	238U std dev	±	Druffel, Ellen R M
6	Percivalia arata	P. arata		Druffel, Ellen R M
7	Thorium-230, standard deviation	230Th std dev	±	Druffel, Ellen R M		2 SE
8	Thorium-232	232Th	µg/kg	Druffel, Ellen R M
9	Thorium-232, standard deviation	232Th std dev	±	Druffel, Ellen R M		2 SE
10	Thorium-232/Thorium-230 ratio	232Th/230Th		Druffel, Ellen R M		atom
11	Thorium-232/Thorium-230, standard deviation	232Th/230Th std dev	±	Druffel, Ellen R M		atom, 2 SE
12	δ234 Uranium	δ234U	‰	Druffel, Ellen R M	Measured
13	δ234 Uranium, standard deviation	δ234U std dev	±	Druffel, Ellen R M	Measured	2 SE
14	Age, dated	Age dated	ka	Druffel, Ellen R M	Age, 230Thorium
15	Age, dated standard deviation	Age dated std dev	±	Druffel, Ellen R M	Age, 230Thorium	2 SE
16	δ234 Uranium	δ234U	‰	Druffel, Ellen R M		initial
17	δ234 Uranium, standard deviation	δ234U std dev	±	Druffel, Ellen R M		initial, 2 SE
18	Age, dated	Age dated	ka	Druffel, Ellen R M	Corrected	corrected
19	Age, dated standard deviation	Age dated std dev	±	Druffel, Ellen R M	Age, 206Pb/207Pb Lead-Lead	corrected, 2 SE
20	δ234 Uranium	δ234U	‰	Druffel, Ellen R M		initial (2)
21	δ234 Uranium, standard deviation	δ234U std dev	±	Druffel, Ellen R M		initial (2), 2 SE
22	AGE	Age	ka BP			Geocode
23	Age, comment	Comm		Druffel, Ellen R M		AGE

License:

Creative Commons Attribution 3.0 Unported (CC-BY-3.0)

Size:

170 data points

Data

Download dataset as tab-delimited text — use the following character encoding:

1 Lab label	2 Sample label	3 Method comm	4 238U [mg/kg]	5 238U std dev [±]	6 P. arata	7 230Th std dev [±] (2 SE)	8 232Th [µg/kg]	9 232Th std dev [±] (2 SE)	10 232Th/230Th (atom)	11 232Th/230Th std dev [±] (atom, 2 SE)	12 δ234U [‰] (Measured)	13 δ234U std dev [±] (2 SE, Measured)	14 Age dated [ka] (Age, 230Thorium)	15 Age dated std dev [±] (2 SE, Age, 230Thorium)	16 δ234U [‰] (initial)	17 δ234U std dev [±] (initial, 2 SE)	18 Age dated [ka] (corrected, Corrected)	19 Age dated std dev [±] (corrected, 2 SE, Age, 206Pb/2...)	20 δ234U [‰] (initial (2))	21 δ234U std dev [±] (initial (2), 2 SE)	22 Age [ka BP]	23 Comm (AGE)
Ed04	LA A1 16-18	H20- dirty	2.8057	0.0015	2.379	0.024	0.145	0.005	60.29	1.22	146.4	1.2	5.0447	0.05313	148.5	1.3	5.0400	0.05181	148.5	1.3	4.977	232Th concentrations for Ed05 were lower than bank level
Ed03	LA A1 16-18	H20	2.7990	0.0014	2.302	0.012	0.043	0.003	18.58	0.08	146.4	1.3	4.8902	0.02653	148.5	1.3	4.8883	0.02584	148.4	1.3	0.217	averaged age
Ed01	LA A1 16-18	Preclean	2.7536	0.0015	2.361	0.013	0.004	0.005	1.69	0.03	147.3	1.3	5.0991	0.03082	149.4	1.3	5.0981	0.03000	149.4	1.3	0.003	2 SD
Ed02	LA A1 16-18	Full clean	2.8459	0.0018	2.367	0.014	0.006	0.005	2.69	0.08	146.2	1.3	4.9469	0.03150	148.3	1.3	4.9461	0.03065	148.2	1.3	0.125
Ed08	LA C1 52-56	H20- dirty	2.6687	0.0013	1.477	0.007	7.359	0.033	4939.09	11.08	147.5	1.2	3.2649	0.01700	148.9	1.2	3.0583	0.19380	148.8	1.2	3.070	232Th concentrations for Ed05 were lower than bank level
Ed07	LA C1 52-56	H20	2.6434	0.0013	1.374	0.007	0.307	0.003	221.69	0.51	147.0	1.3	3.0653	0.01620	148.3	1.3	3.0561	0.01790	148.3	1.3	0.052	averaged age
Ed05	LA C1 52-56	Preclean	2.6097	0.0018	1.373	0.009					148.1	1.2	3.1001	0.02140	149.5	1.2	3.0996	0.02080	149.4	1.2	0.003	2 SD
Ed06	LA C1 52-56	Full clean	2.6498	0.0017	1.374	0.009	0.008	0.007	6.02	0.08	148.0	1.3	3.0543	0.02060	149.4	1.3	3.0536	0.02000	149.3	1.3	0.030