Paleoenvironment Variability during Termination I at the Reykjanes Ridge, North Atlantic

Abstract

The micropaleontological study (radiolarians and foraminifera) of the sediment core AMK-340, Reykjanes Ridge, North Atlantic, combined with the radiocarbon dating and Oxygen/Carbon isotopic record, provided data for the reconstruction of the summer paleotemperature on the water depth of 100 m, and paleoenvironments during the Termination I in the age interval of 14.5–8 ka. The response of the main microfossil species on the paleoceanographic changes within the Bølling-Allerød (BA) warming, the Younger Dryas (YD) cold event, and final transition to the warm Holocene was different. The BA warming was well reflected in the radiolarian and benthic but not planktic foraminiferal record. The high abundances of the cold-water radiolarian species Amphimelissa setosa as the Greenland/Iceland Sea indicator marked a cooling at the end of the BA and within the start of the YD at 13.2–12.3 ka. The micropaleontological and isotopic data together with the paleotemperature estimates for the Reykjanes Ridge at 60° N document that, after the warm BA, the middle YD ca. 12.5–12.2 ka was the next significant step toward the Holocene warming. Start of the Holocene interglacial conditions was reflected in abundant occurrence of the microfossils being indicators of the open boreal North Atlantic environments and lower oxygen isotope values indicating increasing warmth.

Evolution of ocean circulation and water masses in the Guaymas Basin (Gulf of California) during the last 31,000 years revealed by radiolarians and silicoflagellates in IODP expedition 385 sediment cores

“…These taxa were considered for applying a Q-mode factor analysis. Factor analysis is a statistical approach used to identify relationships between variables in a large data set (Pisias et al, 2013;Matul et al, 2018) and to resolve these variables into smaller dimensions with minimum loss of information called factors (Hirama et al, 2010). Q-mode factor analysis is one of the standard statistical techniques for estimating the (paleo) environmental parameters from the micropaleontological data archived in marine sediments (MARGO Project Members, 2009;Ortiz, 2011;Matul and Mohan, 2017), and it is used for improving paleoceanographic inferences based on marine micropaleontological quantitative data sets (Loubere and Qian, 1997;Pisias et al, 2013;Matul and Mohan, 2017).…”

Lithological and biogeochemical investigations of the North Atlantic sediment system (data from the 49th cruise of the R/V Akademik Ioffe)

“…Существуют данные о высоких скоростях седиментации во время голоцена (до 29 см/тыс. лет) в центральной части хребта Рейкьянес [50]. В то же время в северо-восточной Атлантике (57-58° c. ш., 25-28° з.…”

“…Такое низкое содержание карбоната кальция может объясняться наличием большого количества радиолярий в пробах. По данным Матуля с соавторами [50], в колонке МК-340, отобранной на хребте Рейкьянес, также отмечено довольно низкое содержание карбоната кальция в пробах (40-50%) наряду с присутствием достаточно большого количества радиолярий. Однако сохраняется общая тенденция для всех исследуемых колонок -минимальные значения СаСО 3 во время ледниковых стадий и максимальные в периоды межледниковий.…”