Publication Date:
2024-01-09
Description:
The Northwest Pacific Ocean is characterized by a strong mixing of water masses, due to the interplay of three distinct currents, i.e., the Kuroshio, the Tsugaru, and the Oyashio. The C9001C drill core site, located east of the Shimokita Peninsula and directly influenced by the Tsugaru warm current and the Oyashio subarctic current was used here to reconstruct the paleoceanographical history of this region, especially focusing on the Mid-Brunhes Event (MBE) and its consequences. This core provides a continuous record from marine isotope stage (MIS) 18 (740 ka) to the present. Polycystine radiolarian assemblages were analyzed to highlight paleoceanographic and sea surface temperature changes at this site. Based on the radiolarian fauna, seven time periods are defined, which coincide with changes in the dynamics of the Tsugaru and Oyashio currents, respectively. The oldest time interval covered by our analysis (i.e., VII: 740-621 ka) was marked by generally sluggish ocean circulation. The Tsugaru Current influence increased during the following Interval VI (621-478 ka) which encompasses interglacials MIS 15 and 13, while the Oyashio Current strengthened during the Interval V (478-337), i.e. from glacials MIS 12 to 10. These latter intervals (VI to V) constitute a long climatic transitional period where Tsugaru Current and Oyashio Current influences are strengthened. In the time period from Interval IV to Interval I (0-337 ka), the warming intensity of interglacials (MIS 9, MIS 5) appears to be close to the modern one. However, several unusually warm glacials, associated with a relatively strong Tsugaru Current flow, were identified during this interval (e.g., MIS 8 and MIS 6). Radiolarian productivity data suggest that during Intervals VII to V, deep water masses are rich in nutrient content. However, a high vertical mixing event is recorded after Interval IV, when high nutrient concentrations appear to shift to the surface layer.
Keywords:
Acanthodesmia vinculata; Actinomma boreale; Actinomma leptodermum; Amphirhopalum virchowii; Amphisphaera spumacea; Amphisphaera tanzhiyuani; Archiperidium spp.; Axoprunum acquilonium; Bortyostrobus seriatus; Botryocampe inflata; Botryopera cf. chlamida; Botryostrobus aquilonaris; C9001C; Carpocanistrum spp.; Cenosphaera sp.; Ceratocyrtis aff. mashae; Ceratocyrtis spinosiretis; Ceratospyris borealis; Ceratospyris problematica; Cinclopyramis murrayana; Cladoccocus dentata; Cladococcus bifurcus; Cycladophora bicornis; Cycladophora davisiana; Cyrtidosphaera reticulata; DEPTH, sediment/rock; Dictyocoryne muelleri; Dictyocoryne profunda; Dictyocoryne truncatum; Didymocyrtis tetrathalamus; DRILL; Drilling/drill rig; Eucecryphalus cervus; Eucecryphalus sp.; Eucyrtidium acuminatum; Eucyrtidium frohlichi; Flustrella cf. camerina; Flustrella polygonia; Gondwanaria dogieli; Haliomma miocenica; Heliodiscus cf. tunicatus; Hexacontium pachydermum; Lamprocyclas maritalis; Lamprocyrtis sp.; Lamprotripus sp.; Larcopyle buetschlii; Larcopyle cervicone; Larcopyle spp.; Larcopyle weddellium; Lipmanella irregulare; Lithelius haeckelispiralis; Lithelius nautiloides; Lithopera bacca; Lochnosphaera boreale; Lychnocanoma sakaii; Northwestern Pacific Ocean; Ocean Drilling Program; ODP; Phorticium polycladum; Phorticium pylonium; Plagiacantha panarium; Polysolenia spinosa; Pseudodictyophimus gracilipes; Pterocanium korotnevi; Pterocanium praetextum; Pterocorys clausus; Pylodiscus triangularis; Radiolarians, other; Rizosphaera medianum; Sample code/label; Schizodiscus biconcavus; Schizodiscus japonicus; Schizodiscus sp.; Schizodiscus stylotrochoides; Siphonosphaera paraphoros; Siphonosphaera socialis; Sphaeropyle langii; Spongaster tetras irregularis; Spongaster tetras tetras; Spongodiscus resurgens; Spongoliva ellipsoides; Spongopyle osculosa; Spongosphaera boreale; Spongosphaera streptacantha; Spongotrochus helioides; Spongurus cylindricus; Stylochlamydium perichlamydium; Stylochlamydium venustrum; Stylodictya aculeata; Stylodictya validispina; Stylosphaera pyriformis; Tetrapyle octacantha group; Thaecosphaera aequora; Theocorythium trachelium; Tholomura polystyla; Zygocircus cf. piscicaudatus
Type:
Dataset
Format:
text/tab-separated-values, 14507 data points
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