Uranium-Thorium dating results of speleothems from Angelica Cave (central Brazil)

DOI

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.

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.

Identifier
DOI https://doi.org/10.1594/PANGAEA.938678
Related Identifier https://doi.org/10.1016/j.quascirev.2021.107178
Related Identifier https://doi.org/10.1594/PANGAEA.938676
Metadata Access https://ws.pangaea.de/oai/provider?verb=GetRecord&metadataPrefix=datacite4&identifier=oai:pangaea.de:doi:10.1594/PANGAEA.938678
Provenance
Creator Wong, Minn Lin ORCID logo; Wang, Xianfeng ORCID logo; Latrubesse, Edgardo M (ORCID: 0000-0001-5592-302X); He, Shaoneng ORCID logo; Bayer, Maximiliano
Publisher PANGAEA
Publication Year 2021
Rights Creative Commons Attribution 4.0 International; https://creativecommons.org/licenses/by/4.0/
OpenAccess true
Representation
Resource Type Dataset
Format text/tab-separated-values
Size 440 data points
Discipline Earth System Research
Spatial Coverage (-46.240 LON, -13.400 LAT); Brazil