The Distal and Local Volcanic Ash in the Late Pleistocene Sediments of the Termination I Interval at the Reykjanes Ridge, North Atlantic, Based on the Study of the Core AMK-340

Matul Matul,Mikhailova Mikhailova,Khusid Khusid,Gablina Gablina,Libina Libina

doi:10.3390/geosciences9090379

Abstract

We made the geochemical analysis of the volcanic material from the sediment core AMK-340 (the Russian research vessel “Akademik Mstislav Keldysh” station 340), the central zone of the Reykjanes Ridge. Two ash-bearing sediment units within the interval of the Termination I can be detected. They correlate with the Ash Zone I in the North Atlantic Late Quaternary sediments having an age of 12,170–12,840 years within the Younger Dryas cold chronozone and 13,600–14,540 years within the Bølling–Allerød warm chronozone. The ash of the Younger Dryas unit is presented mostly by the mafic and persilicic material originated from the Icelandic volcanoes. One sediment sample from this unit contained Vedde Ash material. The ash of the Bølling–Allerød unit is presented mostly by the mafic shards which are related to the basalts of the rift zone on the Reykjanes Ridge, having presumably local origin. Possible detection of Vedde Ash could help to specify the timing of the previously reconstructed paleoceanographic changes for the Termination I in the point of the study: significant warming in the area might have occurred as early as 300 years before the end of the conventional Younger Dryas cold chronozone.

Highlights

Tephrochronology is a widely used tool for dating and correlating the marine and terrestrial sediment sequences, especially within the Quaternary [1]
The ash of the Younger Dryas unit is presented mostly by the mafic and persilicic material originated from the Icelandic volcanoes
Two sediment units of the core AMK-340, Reykjanes Ridge, North Atlantic, contain a significant amount of volcanic ash. They can be related to the Ash Zone I in the North Atlantic Late Quaternary sediments

Summary

Introduction

Tephrochronology is a widely used tool for dating and correlating the marine and terrestrial sediment sequences, especially within the Quaternary [1]. Icelandic volcanoes are the major source of the ash in the marine sediments of the Nordic Seas and North Atlantic [5]. Thornalley et al [7] detected numerous ash-bearing marine sediment layers south of Iceland within the last deglacial and Holocene time. Such data help to refine the regional and local sediment stratigraphy and synchronize the paleoclimatic archives between the distal oceanic and land regions. Numerous studies of the Late Pleistocene tephra layers in the North Atlantic domain exhibited a complicated mineral/geochemical composition of the ash material accumulated in the marine sediments during the Termination I between approximately 18 and 11 ka (e.g., [8,9,10]). Different processes influence the deposition of the specific ash layers: single eruption or closely-timed chain of eruptions in one locality, Geosciences 2019, 9, 379; doi:10.3390/geosciences9090379 www.mdpi.com/journal/geosciences eruptions dispersal the atmospheric andand oceanic flows, iceberg and sea-ice rafting, dispersal in byone thelocality, atmospheric and by oceanic flows, iceberg sea-ice rafting, and reworking by the and reworking thebioturbation bottom currents bottom currentsbyand [11].and bioturbation [11]

Results

Discussion

Conclusion