FN Archimer Export Format PT J TI Tracing marine cryptotephras in the North Atlantic during the last glacial period: Protocols for identification, characterisation and evaluating depositional controls BT AF ABBOTT, Peter M. GRIGGS, Adam J. BOURNE, Anna J. DAVIES, Siwan M. AS 1:1,2,3,4;2:1;3:1,5;4:1; FF 1:;2:;3:;4:; C1 Swansea Univ, Coll Sci, Dept Geog, Singleton Pk, Swansea SA2 8PP, W Glam, Wales. Cardiff Univ, Sch Earth & Ocean Sci, Pk Pl, Cardiff CF10 3AT, S Glam, Wales. Univ Bern, Inst Geol Sci, Baltzerstr 1 3, CH-3012 Bern, Switzerland. Univ Bern, Oeschger Ctr Climate Change Res, Baltzerstr 1 3, CH-3012 Bern, Switzerland. Univ Southampton, Geog & Environm, Univ Rd, Southampton SO17 1BJ, Hants, England. C2 UNIV SWANSEA, UK UNIV CARDIFF, UK UNIV BERN, SWITZERLAND UNIV BERN, SWITZERLAND UNIV SOUTHAMPTON, UK IF 3.349 TC 19 UR https://archimer.ifremer.fr/doc/00495/60700/83609.pdf LA English DT Article CR IMAGES 1-MD101 IMAGES V LEG 1-MD114 IMAGES V LEG 4-MD114 MD 123 / GEOSCIENCES 1 MD 141 / ALIENOR 1 BO Marion Dufresne DE ;Quaternary;Palaeoceanography;Tephrochronology;North Atlantic;Transport and deposition;Marine cores;Glass shard concentrations AB Tephrochronology is increasingly being utilised as a key tool for improving chronological models and correlating disparate palaeoclimatic sequences. For many sedimentary environments, however, there is an increased recognition that a range of processes may impart a delay in deposition and/or rework tephra. These processes can affect the integrity of tephra deposits as time-synchronous markers, therefore, it is crucial to assess their isochronous nature, especially when cryptotephras are investigated in a dynamic marine environment. A methodology for the identification and characterisation of marine cryptotephras alongside a protocol for assessing their integrity is outlined. This methodology was applied to a wide network of North Atlantic marine sequences covering the last glacial period. A diverse range of cryptotephra deposits were identified and, based on similarities in physical characteristics (e.g. glass shard concentration profiles and geochemical homogeneity/heterogeneity), indicative of common modes of tephra delivery and post-depositional reworking, a deposit type classification scheme was defined. The presence and dominance of different deposit types within each core allowed an assessment of spatial and temporal controls on tephra deposition and preservation. Overall, isochronous horizons can be identified across a large portion of the North Atlantic due to preferential atmospheric dispersal patterns. However, the variable influence of ice-rafting processes and an interplay between the high eruptive frequency of Iceland and relatively lower sedimentation rates can also create complex tephrostratigraphies in this sector. Sites within a wide sector to the south and east of Iceland have the greatest potential to be repositories for isochronous horizons that can facilitate the synchronisation of palaeoclimatic records. PY 2018 PD JUN SO Marine Geology SN 0025-3227 PU Elsevier Science Bv VL 401 UT 000435056400006 BP 81 EP 97 DI 10.1016/j.margeo.2018.04.008 ID 60700 ER EF