Sedimentation rates and age modeling of Late Quaternary marine sediments with unsupported Th-230

Author(s)

de Lima Ferreira, Paulo Alves ; Costa, Karen Badaraco ; de Lima Toledo, Felipe Antonio ; Lopes Figueira, Rubens Cesar

• Document type: Journal article
• Source: JOURNAL OF RADIOANALYTICAL AND NUCLEAR CHEMISTRY; v. 304, n. 2, p. 8-pg., 2015-05-01.

Abstract

Th-230 is a radionuclide of the U-238 decay series, characterized by natural abundance in sediments and a half-life of 75,380 years, suitable for direct evaluation of sedimentation rates and sediment ages in a time scale of 700,000 years before the present. Th-230 cycle creates a contrast between supported and unsupported Th-230 in the sedimentary matrix due to the different geochemical behaviors of Th-230 and its parent, U-234. This study aimed at establishing and validating a mathematical model that evaluates sedimentation rates and age modeling based on Th-230 data retrieved from a sediment core sampled in the southeastern Brazilian continental margin. The validation of the age modeling of this method was made through a statistical comparison between its results and those of benthic foraminifera delta O-18 record technique, widely used for sediment dating and determination of sedimentation rates. It was observed that the model of unsupported Th-230 was successful in determining Late Quaternary sedimentation rates and ages in a confidence level of 95 %. It was possible to determine several breaking points in unsupported Th-230 vertical profile, and it was shown that those divides correspond to some major intervals between glacial and interglacial periods when compared with the benthic foraminifera record. (AU)

• FAPESP's process: 14/08016-6 - Study methods of parameters and processes of marine sedimentary dynamics with natural and artificial radionuclides
• Grantee: Paulo Alves de Lima Ferreira
• Support Opportunities: Scholarships in Brazil - Doctorate