Nanofosilie spodniho campanu v sedimentech na vychodnich svazich mesety Lachman Crags, ostrov Jamese Rosse, Antarktida

Geological research and mapping were performed in the NE part of James Ross Island, NE of the Antarctic Peninsula, Antarctica. The study was carried out on the occasion of the scientific expedition at the J. G. Mendel Czech Antarctic Station. The aim of the study was to investigate the Miocene back-arc alkaline volcanism, but appropriate attention was paid also to underlying Upper Jurassic, Cretaceous and Paleogene deposits of the James Ross Basin. The strata represent part of the infill of the back-arc basin derived from an active arc.
Coniacian to Campanian sediments exposed at on the eastern slopes of the Lachman Crags Meseta were known for the absence of any biostratigraphic data. Poorly to extremely poorly preserved calcareous nannofossils from the light brown sandy siltstones of the Halozetes Valley locality provided the first relevant stratigraphic informations. An assemblage with relative common miniature placoliths of Gephyrobiscutum diabolum and scarce fragments of Eiffellithus eximius and Reinhardtites anthophorus is compared with the southern high-latitude Chiastozygus garrisonii Zone, Gephyrobiscutum diabolum Subzone, respectively, and correlated with the Lower Campanian. The presence of calcareous nannoflora indicates a marine paleoenvironment of normal salinity. G. diabolum considered as an endemic species of Falkland Plateau bears witness to Southern Hemisphere high-latitudes of and to depositional area of James Ross Basin and present Falkland Plateau situated close to each other in the early Campanian.
Nannofossils and foraminifers of the Lower Campanian age have been already found in sediments of the northern part of James Ross Island (Hradecká 2012, Švábenická 2012).

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