Dinoflagellate cyst counts and age model from sediment samples of ODP Hole 175-1085A
Cobertura |
LATITUDE: -29.374410 * LONGITUDE: 13.990110 * DATE/TIME START: 1997-09-26T00:15:00 * DATE/TIME END: 1997-09-29T18:15:00 |
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Data(s) |
24/06/2011
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Resumo |
Sediment samples from ODP Site 1085 were investigated in order to obtain more information on the initiation and development of the Benguela upwelling system during the middle and upper Miocene. In particular, our intent was to establish the causes of the upwelling as well as the response of the upwelling regime to the development of the Antarctic Circumpolar Current. Based on changes in the calcareous dinoflagellate cyst association, we found an initial increase of the dinoflagellate cyst productivity, probably related to the initiation of upwelling about 11.8 Ma ago. Two distinct increases in cyst productivity in conjunction with temperature decreases of the upper water masses reflect upwelling pulses off Namibia and occur at the end of the Miocene cooling events Mi5 (about 11.5 Ma) and Mi6 (about 10.5 Ma). Both cooling events are associated with an ice volume increase in Antarctica and are thought to have led to an increase in southeasterly winds, possibly causing these two upwelling pulses. We demonstrate a decrease in dinoflagellate cyst productivity and enhanced terrigenous input via the Orange River after the Mi5 event. At about 11.1 Ma, the dinoflagellate cyst productivity increases again. The polar cyst species Caracomia arctica occurs here for the first time. This implies an influence of subantarctic mode water and therefore a change in the quality of the upwelling water which allowed the Benguela upwelling to develop into modern conditions. From about 10.4 Ma, C. arctica forms a permanent part of the association, pointing to an establishment of the upwelling regime. |
Formato |
application/zip, 2 datasets |
Identificador | |
Idioma(s) |
en |
Publicador |
PANGAEA |
Direitos |
Access constraints: access rights needed |
Fonte |
Supplement to: Heinrich, Sonja; Zonneveld, Karin A F; Bickert, Torsten; Willems, Helmut (2011): The Benguela upwelling related to the Miocene cooling events and the development of the Antarctic Circumpolar Current: Evidence from calcareous dinoflagellate cysts. Paleoceanography, 26(3), PA3209, doi:10.1029/2010PA002065 |
Palavras-Chave | #-; Age; AGE; C. albatrosianum; C. arctica; C. kullenbergi d18O; C. levantinum; C. operosum; C. wuellerstorfi d18O; Calciodinellum albatrosianum; Calciodinellum levantinum; Calciodinellum operosum; Calculated; Caracomia arctica; Cibicidoides kullenbergi, d18O; Cibicidoides wuellerstorfi, d18O; Counting, dinoflagellate cysts; Depth; DEPTH, sediment/rock; Dinoflagellate cyst per unit mass; Dinoflagellate indeterminata; Dinofl cyst; Dinofl indet; Dry volume; Eppendorf cup (µl); gram counted; L. granifera; Label; Leonella granifera; Mass; Number of species; Ocean Drilling Program; ODP; others; P. parva; P. schizosaeptum; P. tuberosa; Pernambugia tuberosa; Pirumella parva; Praecalcigonellum schizosaeptum; R. spp.; Rhabdothorax spp.; S. regalis; Sample code/label; Scrippsiella regalis; Slide (µl); Spec. A; Spec No; T. heimii; Thoracosphaera heimii; Volume; weight |
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