Trabalho de Graduação - Lucas M. Bariani

VARIAÇÕES DA SEDIMENTAÇÃO AO LONGO DOS ÚLTIMOS 15.000 ANOS EM UM TESTEMUNHO DA BACIA DE SANTOS

Bariani, L. M., Toledo, F.A.L.

Marine sediments from Santos Basin continental slope have been investigated by grain size, X-ray fluorescence and carbonate content from one piston core. The core KF-02 (25^o 50’15,25’’ S; 45^o 15’ 53,72’’ W; 827 mbsl) is 489 cm long and ~15 kyrs old. The core was sampled every 4 cm, totalizing 111 samples. Chronological control is based on 9 AMS radiocarbon dates. Comparison among the sedimentological record with previous micropaleontological and geochemical records from this core was realized. From grain size analyses we observed that clay percentage showed relatively low concentrations in the lower core section and higher values toward the core top. The X-ray fluorescence showed that the Fe/Ca, Ti/Ca and Mg/Ca element ratios were very similar among themselves, but we do not observed a significant correlation with the other proxies studied. The same occurred with the grain size analyses. The oscillations of carbonate content are coherent with bulk sample oxygen isotopes from the lower core section until ~3 kyrs BP and both can be correlated with water temperature variations (higher carbonate contend and higher oxygen isotopes related with warmer water temperatures). From this age toward the core top these proxies showed opposite behavior: lower carbonate content and higher oxygen isotopes, suggesting that others factors should be acting to explain the observed signal in the marine sediments.