Sequential Determination of U and Th DecaySeries in Santana Cave, Southwest Brazil

摘要

Parque Estadual Turistico do Alto Ribeira (PETAR) is located in the South-westernpart of Sao Paulo State, in the Ribeira Valley. In this national state park a large number of cavesare found, which are among the most visited of the country. These caves, located in a karstic zone,are characterized by the presence of carbonaceous rocks frequently fractured and collapsed.Although, carbonates (dolomites and calcitic rocks) usually have low U content, this element canbe found in the structure of the surrounding rocks. This paper aims to determine ~(238)U, ~(234)U, ~(226)Raand ~(210)Pbconcentration in samples of rock, soil, river water and sediment, in Santana cave. Theradionuclide ~(238)Uwas determined by alpha spectrometry using a surface barrier detector. ~(226)Raand~(210)Pbwere determined by measuring the gross alpha and beta activity on a gas flow proportionalcounter.