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Pleistocene chronostratigraphy of the southeastern White Sea and adjacent areas (Arkhangelsk region, Russia)тезисы доклада Электронная публикация
- Авторы: Zaretskaya N.E., Shilova O.S., Repkina T.Yu
- Сборник: INQUA 2019 Abstracts
- Тезисы
- Год издания: 2019
- Первая страница: P-4637
- Аннотация: The White Sea which is an inner basin of the Arctic Ocean located in the Northwestern Russia is of high geological interest because of its binary structure: its northwestern half is located on the tectonically active Baltic crystalline shield, and the southeastern one is a part of the East European platform with developed sedimentary mantle and comprises the onshore areas of the Onezhski peninsula, Kuloi plateau and southern side of the Gorlo strait (Fig. 1). According the current Quaternary System subdivisions for European Russia (Zastrozhnov et al., 2018) it lies within the Northwestern subzone of Late Neopleistocene glaciations (W-Ia). The Quaternary stratigraphy starts with Eemian which deposits are widespread both within the Gorlo strait and in the coastal zone (Demidov et al., 2007; Sobolev, 208; Rybalko et al., 2017) and are mostly marine sands and silty sands with shells and shell detrital matter. The luminescent dating results are 160-110 kyr BP (Sobolev et al., 1995). In the coastal outcrops these deposits are presented by binary layer of dark-grey massive clays covered by light-grey sands, often directly overlain by LGM deposits. The middle Weichselian interstadial deposits were identified in one section of Zimniy coast and are presented by sands and gravels interlayered with silts and loams. The origin is controversial: fluvial (Larsen et al., Demidov et al., 2006) or marine (Sobolev, 2008). One radiocarbon date is 27.9±1.16 (shells), and TL dates are 55.8±8, 63.0±11 and 71.0±11 BP (Sobolev, 2008), OSL-dates are 77±8, 31±3 and 19.9±1.4 (Demidov et al., 2006). Late Weichselian (LGM and deglaciation) tills are the most widespread in this area (Demidov et al., 2006; 2007; Rybalko et al., 2017), forming the gently undulating uplands with blanket bogs. This area was covered by last SIS glacier from 22 to 16-15 kyr BP (Hughes et al., 2015). The thickness of till layer varies from 1 to 8-9 m, and sometimes is underlain by the rhythmically interlayered sands and clays probably deposited in proglacial conditions of early LGM. The deglaciation of this area left the well expressed marginal landforms; moraine ridges of Neva deglaciation stage (Older Dryas) are identified both in the coastal area (State…, 2012) and within the Gorlo strait (Sobolev, 2008; Rybalko et al., 2017). The Late Glacial – early Holocene basin deposits are found up to the height of 14-20 m a.s.l., and the Holocene marine (supported by diatom data) - up to 4-5 m a.s.l.; these are grayish or brownish-grey heavy silts and clays, usually covered by aeolian sands or peat and gyttja. This work was supported by RFBR grants 17-05-00706 (chronostratigraphy) and 19-05-00966 (geomorphology, diatom analysis). https://app.oxfordabstracts.com/events/574/program-app/submission/92022
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