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Sea Level Fluctuations, Oceanic Sedimentation, and Climate Precessionfor the Last 130 Thousand Years
Based on our previously performed calculations of the intensity of Earth’ irradiation at the top of the atmosphere with high spatial and temporal resolution, it has been confirmed that the sea level rise over at least the last 130,000 years (during the Eemian / Mikulino interglacial and the late Pleistocene – Holocene) is associated with warm phases of climate precession. Based on our calculations of summer/winter irradiation intensity extremes during climate precession phases in the Northern Hemisphere, the formation dates of dropstones (Heinrich layers ) have been refined. These dropstones are correlated with climate precession extremes and are recorded in ocean sediments during both interglacial and glacial periods. Sea level evolution and ocean sedimentation over the past 130,000 years are primarily determined by glacioeustatic fluctuations associated with temperature changes, which are primarily controlled by variations in the intensity of Northern Hemisphere irradiation within the climatic precession cycle. At the same time, the weak presence of a precessional cycle is noted in the benthic δ18 O stack of the orbitally tuned LR04 scheme/model, which currently forms the basis of geochronology and climatostratigraphy of Late Pleistocene and Holocene. The beginning of the next warm phase of climate precession is expected around 5,500 years AD. This phase will peak around 11.5 kyr AD, when the next significant sea level rise is expected.
CLIMATE VARIATIONS IN THE SOUTH KARA SEA BASIN’S EVOLUTION
The paleoclimate evolution curve of the South Kara Sea basin over the past 250 Myr, which is necessary for numerical reconstruction of its thermal history, was plotted using data from a large number of works devoted to studying of the paleoclimate of the Arctic sector of the West Siberian Basin. For the period from 260 to 65 Mya, the construction of the paleoclimate curve was based on a series of paleotectonic reconstructions of the studied area. The reconstruction of the climatic history of the Cenozoic was based on a detailed study of climate variations in Eurasia over the past 65 Myr. The history of sharp climate fluctuations in the last 3.5 Myr was based on information from a large number of works devoted to studying of the regional paleoclimate in the Pliocene-Quaternary. Studies published in the literature speak in favor of the limited size of the glacial covers formed within the South Kara basin. This makes it possible to neglect the effect of the porosity of sedimentary rocks from the glacial cover load in comparison with the similar effect of the load of sediments removed by erosion in the Miocene. Any correction to the paleoclimatic data due to the thermal influence of the ice sheet with its limited thickness should not exceed the error in determining the data themselves. Peculiarities in the change in temperature and the salinity of pore waters with depth determine the existence of various forms of permafrost in the shelf areas of the Arctic seas.