Diatom abundance in middle-to-late Pleistocene sediments of IODP Site 303-U1304


Autoria(s): Shimada, Chieko; Sato, Tokiyuki; Toyoshima, Saiko; Yamasaki, Makoto; Tanimura, Yoshihiro
Cobertura

LATITUDE: 53.000000 * LONGITUDE: -33.529000

Data(s)

09/01/2008

Resumo

We examined diatom assemblages in a series of remarkable laminated diatomaceous ooze (LDO) horizons in the marine sediments from Integrated Ocean Drilling Program (IODP) Site U1304 to reconstruct the middle-to-late Pleistocene paleoceanographic evolution of the northern North Atlantic Ocean. Four confirmed diatom biohorizons combined with calcareous nannofossil and paleomagnetic stratigraphies established the chronological framework for the material. The planktonic, araphid, needle-like species Thalassiothrix longissima was the greatest contributor to the LDO facies. From the results of a principal component analysis using the percent abundances of 65 significant (p = 5%) diatom taxa, except for Tx. longissima, which was extremely dominant in almost all horizons observed, we identified two principal component (PC) axes. Taxa probably associated with the stratigraphic distribution of the major zonal marker Neodenticula seminae (ranging from 1.26 to 0.84 Ma in this ocean) loaded on PC1 with a high value. PC2 was related to the ocean surface temperature. The stratigraphic variability of the PC2 score indicated that switching between warm- and cold-water assemblages occurred concurrently with LDO deposition (or extreme Tx. longissima dominance) episodes in several horizons (particularly after 0.84 Ma), suggesting that the Subarctic Convergence (SAC) oceanic front passed over Site U1304 during Pleistocene glacial/interglacial cycles. Our floral evidence supports the model of nearly monospecific LDO formation caused by the enhanced physical accumulation of particular diatoms such as Tx. longissima. On the other hand, Nd. seminae, which probably contributes to spring phytoplankton blooms in the modern ocean, was present only between 1.26 and 0.84 Ma in this area. Thus, we infer that the main contributor of export flux in the regional annual primary production cycle would have shifted drastically from one of a spring phytoplankton bloom leader (Nd. seminae) to minor but mass dump assemblages (Tx. longissima etc.) in the mid-Pleistocene.

Formato

application/zip, 2 datasets

Identificador

https://doi.pangaea.de/10.1594/PANGAEA.773687

doi:10.1594/PANGAEA.773687

Idioma(s)

en

Publicador

PANGAEA

Direitos

CC-BY: Creative Commons Attribution 3.0 Unported

Access constraints: unrestricted

Fonte

Supplement to: Shimada, Chieko; Sato, Tokiyuki; Toyoshima, Saiko; Yamasaki, Makoto; Tanimura, Yoshihiro (2008): Paleoecological significance of laminated diatomaceous oozes during the middle-to-late Pleistocene, North Atlantic Ocean (IODP Site U1304). Marine Micropaleontology, 69(2), 139-150, doi:10.1016/j.marmicro.2008.07.004

Palavras-Chave #303-U1304; A. curvatulus; Actinocyclus curvatulus; Age; AGE; Age model; Age model, biostratigraphy; Ageprof dat des; Ageprofile Datum Description; Ages based on Koc et al. (1999); C. marginatus; COMPCORE; Composite Core; Coscinodiscus marginatus; Counting, light microscope; Depth; Depth, bottom/max; DEPTH, sediment/rock; Depth, top/min; Depth bot; Depth top; Exp303; F. doliolus; F. fossilis; Fragilariopsis doliolus; Fragilariopsis fossilis; Integrated Ocean Drilling Program / International Ocean Discovery Program; IODP; Joides Resolution; Label; Label 2; N. reinholdii; N. seminae; Neodenticula seminae; Nitzschia reinholdii; North Atlantic; North Atlantic Climate 1; ODP sample designation; P. alata; P. curvirostris; Proboscia alata; Proboscia curvirostris; R. bergonii; R. borealis; R. hebetata f subacuta; R. styliformis; R. tesselata; Rhizosolenia bergonii; Rhizosolenia borealis; Rhizosolenia hebetata forma subacuta; Rhizosolenia styliformis; Roperia tesselata; Sample code/label; Sample code/label 2; T. longissima; T. nitzschioides var. nitzschioides; T. oestrupii; Thalassionema nitzschioides var. nitzschioides; Thalassiosira oestrupii; Thalassiothrix longissima
Tipo

Dataset