Composition and origin of ash zones from Marine Isotope Stages 3 and 2 in the North Atlantic

Abstract

The composition and distribution of four North Atlantic ash zones from the Faroe Islands margin is presented, including the widespread North Atlantic Ash Zone II (NAAZ II; 52–53 ka BP) and three mainly basaltic ash zones here referred to as the Faroe Marine Ash Zones (FMAZ) I (ca 15.4 14C ka BP), II (ca 23 14C ka BP, also referred to as the Fugloyarbanki Tephra) and III (ca 33 14C ka BP). One core from the south-east Labrador Sea was also analysed. NAAZ II was found in all investigated cores, indicating very large eruption events in the early Marine Isotope Stage (MIS) 3. Detailed investigations of NAAZ II in high-resolution cores show that two separate layers can be distinguished; a lower mixed alkalic basalt and rhyolitic layer and an upper predominantly tholeiitic basalt tephra. The main component of the basaltic FMAZ II was found in all cores from the Faroe Island margin and the Labrador Sea indicating that this tephra is the most widespread tephra from MIS 2 in the North Atlantic discovered so far. We discuss the possibility to use these tephra layers for exact correlations between marine records and land sections such as the Greenland ice-cores and terrestrial records on the European mainland.