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Abstarct: Jeju Island, which lies on the continental shelf in the southern Korean Peninsula, is the emergent portion of a basaltic volcanic field that has erupted since the Early Pleistocene (ca. 1.8 Ma). Volcanic activity that continued into historic times (ca. 1 ka) formed an elongated shield with a central edifice (Mt. Halla) and more than 300 monogenetic cones and rings. The establishment of a temporal framework for Jeju volcanism, particularly during the Late Pleistocene and Holocene activities, requires geochronological tools other than radiometric dating techniques, which are based on parent-daughter isotope pairs with geologically long half-lives, such as 40Ar/39Ar dating. In this study, we conducted quartz optically stimulated luminescence (OSL) dating of palaeosols intercalated with basaltic lava flows and scoria deposits, presumably ejected from three monogenetic volcanoes (Cheoreum, Darangsh and Dunjibong volcanoes) in the northeastern part of the island. Quartz extracts from the palaeosols had moderate to dim sensitivity to optical stimulation, but several prerequisite tests of the measurement protocols for equivalent dose estimation were successful. The coarse (63–250 μm) and fine (4–11 μm) quartz fractions yielded continuous wave (CW)-OSL ages of 19.9–7.0 and 18.6–6.7 ka, respectively, both of which were broadly consistent with the radiocarbon dates (10245–7440 Cal yr BP). These ages indicate that lava flows and scoria deposits covering the palaeosols are younger than ~7 ka. The pulsed OSL signals in coarse quartz extracts from the palaeosols suffered from poor counting statistics, thus it is recommended that they not be applied solely (i.e., without any other absolute ages to compare) to dating dim samples. From one of the sites investigated here, the averaged sedimentation rate of the palaeosol is estimated to be ~0.05 mm/yr, based on stratigraphically consistent CW-OSL ages. The OSL ages presented in this paper, together with previous OSL and radiocarbon ages, confirm that Jeju volcanic island was regionally active during the Holocene. [ABSTRACT FROM AUTHOR]

Understanding of past climate variability on millennial to decadal scales are of primary importance in order to assess modern processes and predict future climatic events. Past history of Arctic climate changes is currently receiving increasing attention due to the recent phenomena of rapid sea-ice reduction. In this paper, we thoroughly reviewed the Holocene history of spatiotemporal climatic changes in the western Arctic region in order to better understand recent rapid environmental changes occurring in the Pacific sector of the Arctic, and further to discuss critical issues and new perspectives on the western Arctic in terms of paleoclimate researches. Records of temporal and spatial variations in sea-ice extents as well as marine and terrestrial paleoclimatic proxies show a strong asynchronicity between the western and eastern Arctic throughout the Holocene. The reason for this apparent contradiction across the Arctic may be linked to freshwater discharges over the Arctic shelves and the inflow of the Pacific freshwater into the western Arctic Ocean in coupled with a complex interaction between atmospheric and sea-ice dynamics. Special emphasis is placed on a tentative linkage of the late Holocene paleoclimatic events between the Arctic regions and the northwestern Pacific margin, highlighting the notion that climatic events of the northern Pacific Ocean is closely linked to the global climate system through hydrological dynamics in the western Arctic Ocean. [ABSTRACT FROM AUTHOR]

A first quasi-successive paleosecular variation data since ∼5.5 kya, including magnetic inclination and relative geomagnetic field intensity variation were obtained from a 55 m-long sediment core in the Nakdong River delta, southeastern Korean Peninsula. Both magnetic inclination curves and relative paleointensity data showed similar trends with those from Lake Biwa, Japan. They also showed close correlation with continuous global geomagnetic field models. For instance, the present study confirms the existence of archeomagnetic jerks. In addition, the present study supports the evidence of globally high geomagnetic intensity circa 3 kya. [ABSTRACT FROM AUTHOR]

We represent Paleoenvironmetal condition of Vestfold Hills region, based on the relative abundance of a single diatom species Fragilariopsis curta, a dominating sea-ice taxon. Increase in relative abundance of F. curta in a core from Vestfold Hills representing Holocene climatic history before 3820 years BP and 5560 year BP indicates the prevalence of colder climatic conditions, as this species is known to prefer the icier condition to thrive. [ABSTRACT FROM AUTHOR]

To investigate the Holocene vegetation and climate changes, pollen analysis performed on swamp deposits of the Boseong area, South Korea. From ca. 11,800 to 10,500 cal. yr BP, a cool temperate deciduous broadleaved forest dominated by Alnus and Quercus (Lepidobalanus) occupied the study area, indicating climatic warming during the Preboreal (earliest Holocene). A remarkable decrease in riparian Alnus and an increase in xerophytic Artemisia from ca. 10,500 to 8,400 cal. yr BP suggest open woodland with herbaceous understory reflecting a cool and dry condition. The expansion of deciduous broadleaved forest combined with rise in evergreen broadleaved taxa and the retreat of grassland between ca. 8,400 and 3,700 cal. yr BP indicate a vegetation shift from open woodland with herbaceous understory to warm temperate evergreen and deciduous broadleaved forests, resulted from climate amelioration during the Holocene climatic optimum. A warm and humid condition during this period is also evidenced by high values of pollen concentration. Vegetation change controlled by human impact occurred from ca. 3,700 to 2,900 cal. yr BP, as indicated by a rise in Pinus and Polypodiaceae and by high sedimentation rate. Along with the late Holocene climatic cooling, human impact brought about the development of Pinus dominated open woodland with a fern (Polypodiaceae) understory in the Boseong area. [ABSTRACT FROM AUTHOR]

Selected intervals of laminated diatom ooze (Holocene) from the eastern Bransfield Strait, Antarctic Peninsula were analyzed using high-resolution section images of impregnated samples to reveal potential annual-to-seasonal scale signatures of the lamination. The results show a probable seasonality within individual diatom ooze laminae which mainly reflects spring blooms of Chaetoceros followed by summer production of Corethron or Rhizosolenia. Alternating monospecific diatom ooze and terrigenous laminae are suggestive of annual cyclicities, representing alternation of diatom mass flux during the spring or autumn with terrigenous flux during the rest of year. [ABSTRACT FROM AUTHOR]