The Campanian–Maastrichtian interval at The Naze, James Ross Island, Antarctica: microbiostratigraphic and paleoenvironmental study

Abstract

A biostratigraphic and paleoenvironmental characterization of the CampanianeMaastrichtian deposits on The Naze (James Ross Island, Antarctica) based on the foraminiferal assemblages, lithofacies analysis, and Hg/total organic carbon (TOC) data was developed. The sedimentary deposits mapped in The Naze region showed an association of four sedimentary lithofacies, including greenish-gray claystone, shales with levels of concretion, bioturbated marl, and sandstone. The sedimentary deposits have been covered by a fifth lithofacies, the James Ross Island Volcanic Group (JRIVG), which consists of pyroclastic rocks interbedded with basalt bodies. The association of agglutinated foraminifera was found to consist mainly of Rzehakina epigona, Trochammina ribstonensis, Gaudryina healyi, Karreriella aegra, Dorothia elongata, Alveolophragmium macellarii, Cyclammina complanata and Spiroplectammina spectabilis, that allow to infer a Campanianeearly Maastrichtian age to the studied interval. An association of opportunistic agglutinated foraminifera predominated in this stressful environment. The absence of Hg-TOC unassociated excursions ruled out distal volcanism as a source of environmental stress, while Hg/TOC ratio variability suggested that regional oceanic processes were the major environmental change driver.