Citation:

PANGAEA.938678

Name: Uranium-Thorium dating results of speleothems from Angelica Cave (central Brazil)
Published: 2021-11-29
License: https://creativecommons.org/licenses/by/4.0/
Keywords: South American Monsoon System; Speleothems; Stable isotope

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Abstract:

Here we present a speleothem oxygen isotope (δ18O) and carbon isotope (δ13C) record from Angelica Cave in central Brazil (13.40°S, 46.23°W, ~585 m above sea level). The record is based on three stalagmite samples, AG1, AG2 and AG4. Ages of the samples were constrained by high-precision U-Th disequilibrium dating performed using a Thermo‐Fisher Scientific Neptune Plus multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS). The three samples have a combined temporal coverage of 0.1-6.8 kyr BP, roughly spanning the mid-to-late Holocene. Stable isotope values were measured using a GasBench coupled to a Delta-V isotope ratio mass spectrometer (IRMS) system. Angelica δ18O and δ13C values display an overall relatively flat trend with time. The Angelica Cave underlies the core of the South Atlantic Convergence zone (SACZ). The δ18O record can therefore be interpreted as proxy for SACZ rainfall intensity. The relatively flat δ18O trend over the past 6.8 kyr BP suggests that SACZ rainfall intensity remained largely invariant during the mid-to-late Holocene, despite the rising South Hemisphere summer insolation and increasing monsoon strength in the core South American Summer Monsoon zone. The Angelica δ18O record also shows no clear expression of abrupt North Atlantic events, such as the Little Ice Age, Medieval Climate Anomaly and Bond Events.

Keyword(s):

South American Monsoon System; Speleothems; Stable isotope

Supplement to:

Wong, Minn Lin; Wang, Xianfeng; Latrubesse, Edgardo M; He, Shaoneng; Bayer, Maximiliano (2021): Variations in the South Atlantic Convergence Zone over the mid-to-late Holocene inferred from speleothem δ18O in central Brazil. Quaternary Science Reviews, 270, 107178, https://doi.org/10.1016/j.quascirev.2021.107178

Related to:

Wong, Minn Lin; Wang, Xianfeng; Latrubesse, Edgardo M; He, Shaoneng; Bayer, Maximiliano (2021): Stable isotope (δ18O,δ13C) results of speleothems from Angelica Cave (central Brazil). PANGAEA, https://doi.org/10.1594/PANGAEA.938676

Coverage:

Latitude: -13.400000 * Longitude: -46.240000

Minimum Elevation: 565.0 m * Maximum Elevation: 565.0 m

Event(s):

Angelica_Cave (AG) * Latitude: -13.400000 * Longitude: -46.240000 * Elevation: 565.0 m * Location: Brazil * Method/Device: Multiple investigations (MULT)

Comment:

δ234U = ([234U/238U]activity – 1)x1000.

δ234Uinitial was calculated based on 230Th age (T), i.e., d234Uinitial = d234Umeasured x el234xT.

Corrected 230Th ages assume the initial 230Th/232Th atomic ratio o 4.4 2.2 x10-6. Those are the values or a material at secular equilibrium, with the bulk earth 232Th/238U value o 3.8. The errors are arbitrarily assumed to be 50%.

The error is 2s error.

Parameter(s):

#	Name	Short Name	Unit	Principal Investigator	Method/Device	Comment
1	Sample code/label	Sample label		Wong, Minn Lin
2	Depth, relative	Depth rel	m	Wong, Minn Lin
3	Uranium-238	238U	µg/kg	Wong, Minn Lin
4	Uranium-238, standard deviation	238U std dev	±	Wong, Minn Lin
5	Thorium-232	232Th	ng/kg	Wong, Minn Lin
6	Thorium-232, standard deviation	232Th std dev	±	Wong, Minn Lin
7	Thorium-230/Thorium-232 atomic ratio	230Th/232Th atom		Wong, Minn Lin
8	Thorium-230/Thorium-232 atomic ratio, standard deviation	230Th/232Th atom std dev	±	Wong, Minn Lin
9	δ234 Uranium	δ234U	‰	Wong, Minn Lin
10	δ234 Uranium, standard deviation	δ234U std dev	±	Wong, Minn Lin
11	Thorium-230/Uranium-238 activity ratio	(230Th/238U)		Wong, Minn Lin
12	Thorium-230/Uranium-238 activity ratio, standard deviation	(230Th/238U) std dev	±	Wong, Minn Lin
13	Age, dated	Age dated	ka	Wong, Minn Lin	Age, 230Thorium, uncorrected
14	Age, dated standard deviation	Age dated std dev	±	Wong, Minn Lin	Age, 230Thorium, uncorrected
15	Age, dated	Age dated	ka	Wong, Minn Lin	Age, 230Thorium	corrected, relative to the time of measurement
16	Age, dated standard deviation	Age dated std dev	±	Wong, Minn Lin	Age, 230Thorium	corrected, relative to the time of measurement
17	δ234 Uranium (0)	δ234U (0)	‰	Wong, Minn Lin
18	δ234 Uranium (0), standard deviation	δ234U (0) std dev	±	Wong, Minn Lin
19	Age, dated	Age dated	ka	Wong, Minn Lin	Age, 230Thorium	corrected, relative to 1950
20	Age, dated standard deviation	Age dated std dev	±	Wong, Minn Lin	Age, 230Thorium	corrected, relative to 1950

License:

Creative Commons Attribution 4.0 International (CC-BY-4.0)

Status:

Curation Level: Enhanced curation (CurationLevelC)

Size:

440 data points

Data

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

1 Sample label	2 Depth rel [m]	3 238U [µg/kg]	4 238U std dev [±]	5 232Th [ng/kg]	6 232Th std dev [±]	7 230Th/232Th atom	8 230Th/232Th atom std dev [±]	9 δ234U [‰]	10 δ234U std dev [±]	11 (230Th/238U)	12 (230Th/238U) std dev [±]	13 Age dated [ka] (Age, 230Thorium, uncorrected)	14 Age dated std dev [±] (Age, 230Thorium, uncorrected)	15 Age dated [ka] (corrected, relative to the ti...)	16 Age dated std dev [±] (corrected, relative to the ti...)	17 δ234U (0) [‰]	18 δ234U (0) std dev [±]	19 Age dated [ka] (corrected, relative to 1950, ...)	20 Age dated std dev [±] (corrected, relative to 1950, ...)
AG1 - 1	0.001	1695	5	555	11	0.000109	0.000003	336.5	2.0	0.0022	0.0000	0.177	0.003	0.170	0.006	337	2	0.101	0.006
AG1 - 29	0.029	2569	4	788	18	0.000277	0.000007	351.1	1.9	0.0052	0.0001	0.417	0.005	0.410	0.007	351	2	0.341	0.007
AG1 - 54	0.054	2639	5	49	8	0.006074	0.000943	351.0	1.9	0.0069	0.0001	0.556	0.005	0.556	0.005	352	2	0.487	0.005
AG1 - 108	0.108	2622	4	35	8	0.016685	0.003923	349.3	1.7	0.0136	0.0001	1.108	0.008	1.108	0.008	350	2	1.039	0.008
AG1 - 137	0.137	2564	5	48	8	0.016321	0.002836	344.3	1.9	0.0185	0.0001	1.508	0.010	1.507	0.010	346	2	1.438	0.010
AG1 - 192	0.192	1426	4	488	10	0.001168	0.000025	337.4	2.2	0.0242	0.0002	1.993	0.015	1.986	0.016	339	2	1.917	0.016
AG2-1	0.001	2444	11	2502	51	0.000409	0.000009	419.3	3.0	0.0254	0.0002	1.966	0.015	1.945	0.021	422	3	1.876	0.021
AG2-4	0.004	1697	2	817	22	0.000960	0.000027	379.3	1.9	0.0281	0.0002	2.239	0.020	2.229	0.021	382	2	2.160	0.021
AG2-15	0.015	2286	3	234	15	0.005117	0.000325	385.4	1.8	0.0318	0.0002	2.527	0.020	2.524	0.020	388	2	2.455	0.020
AG2-25	0.025	1522	2	236	13	0.003698	0.000199	387.4	1.6	0.0348	0.0003	2.769	0.022	2.766	0.022	390	2	2.697	0.022
AG2-32	0.032	1451	2	162	14	0.005321	0.000454	361.7	1.6	0.0361	0.0003	2.931	0.024	2.928	0.024	365	2	2.859	0.024
AG2-80	0.080	3213	4	170	11	0.014532	0.000950	284.6	1.7	0.0465	0.0002	4.017	0.016	4.015	0.016	288	2	3.946	0.016
AG2-121	0.121	1727	2	343	11	0.004366	0.000145	302.4	1.8	0.0526	0.0002	4.484	0.022	4.480	0.022	306	2	4.411	0.022
AG2-122	0.122	3400	6	121	10	0.024264	0.002044	294.7	2.2	0.0523	0.0003	4.488	0.029	4.487	0.029	298	2	4.418	0.029
AG2-166	0.166	2592	3	673	15	0.003845	0.000089	311.7	1.9	0.0605	0.0002	5.141	0.022	5.135	0.022	316	2	5.066	0.022
AG2-200	0.200	2152	4	141	4	0.016684	0.000513	287.6	1.9	0.0663	0.0002	5.753	0.023	5.751	0.023	292	2	5.682	0.023
AG2-226	0.226	2412	3	792	17	0.003583	0.000078	289.5	1.9	0.0714	0.0002	6.195	0.019	6.188	0.020	295	2	6.119	0.020
AG2-261	0.261	2056	9	348	7	0.007640	0.000171	315.0	2.6	0.0783	0.0006	6.682	0.052	6.679	0.052	321	3	6.610	0.052
AG4-3	0.003	4486	26	600	13	0.008213	0.000178	208.2	3.0	0.0666	0.0005	6.176	0.049	6.173	0.049	212	3	6.104	0.049
AG4-56	0.056	2832	3	59	6	0.054998	0.005512	208.5	1.9	0.0694	0.0002	6.440	0.019	6.439	0.019	212	2	6.370	0.019
AG-109	0.109	2765	3	137	11	0.023257	0.001898	183.2	1.8	0.0700	0.0002	6.641	0.024	6.639	0.024	187	2	6.570	0.024
AG-170	0.170	4976	23	473	10	0.012784	0.000276	197.0	2.6	0.0737	0.0004	6.921	0.046	6.919	0.046	201	3	6.850	0.046