Lake Imandra depression in the Late Glacial and early Holocene (Kola Peninsula, north-western Russia)

Abstract

The paper summarizes the evidence of litho-, biostratigraphy and 14C dating of sedimentary sequences studied in natural outcrops and bottom deposits in small lakes, as well as data on coastal morphology in the depressions of Ekostrovskaya and Babinskaya Imandra, the southern sub-basins of Lake Imandra. Lithological, 14C and diatom data suggest that the brackish-water reservoir followed by the fresh-water one existed in the Ekostrovskaya Imandra depression during the Younger Dryas chronozone prior to 11,400cal. yr BP. The Fennoscandian Ice Sheet margin is assumed to have been located in the Lake Imandra basin, covering western Babinskaya Imandra earlier than c. 10,250 cal. yr BP. The early Holocene c. 11,400–8,500 cal. yr BP was marked by a significant westward retreat of the ice margin in the western Lake Imandra depression and adjacent areas, and an extensive fresh-water pra-Imandra Lake basin was formed there. At the end of the Preboreal, earlier than c. 9,210–8,500 cal. yr BP, the pra-Imandra Lake coastline was at least 16–18 m higher than the modern one, as can be assumed according to coastal morphology and lithostratigraphical data. The coastline of that reservoir changed, water square slightly reduced, and isolated small lakes emerged on coasts during the early Holocene.

Holocene environments on the west‐central Kola Peninsula (north‐west Russia): lithology, chronology and biostratigraphy records from Lake Tikozero and a neighbouring bog

“…11 550 cal a bp and is marked by a transition from glaciolacustrine to lacustrine sedimentation. This corresponds to other sedimentological and bio‐ and chronostratigraphical records from the northern Kola Peninsula (Snyder et al ., 2000; Kremenetski et al ., 2004) and the west‐central Kola region (Solovieva and Jones, 2002; Tolstobrova et al ., 2016; Korsakova et al ., 2020).…”

“…Due to the glacio‐isostatic load and high amount of glacier meltwater inflow, the shoreline of Lake pre‐Imandra in the Late Glacial and probably in the earliest Holocene was located about 16–18 m higher than the modern one, as evidenced by the highest terrace at 142–143 m a.s.l. (Korsakova et al ., 2020). In the earliest Holocene, the Lake pre‐Imandra shoreline lowered, as also suggested by changes in the cladoceran assemblages in the deep core from the northern part of Lake Imandra (Lenz et al ., 2021).…”

“…6) indicate a lake level lowstand. The occurrence of halophilous diatoms in the sand from Lake Tikozero seems to be inherited from the Late Glacial brackish body of water in the Lake Ekostrovskaya Imandra depression that existed here during deglaciation (Tolstobrova et al ., 2016; Korsakova et al ., 2020). This was suggested based on diatom data from outcrops in Ekostrovskaya Imandra and eastern Babinskaya Imandra depressions, where oligohalobous halophiles, meso‐ and polyhalobous diatoms occur up to 136–138 m a.s.l.…”

“…1B), at an altitude of up 190 m above sea level (a.s.l.) provided new lithological and micropalaeontological data, as well as chronological constraints based on 14 C dating (Nikolaeva et al ., 2015, 2017; Tolstobrova et al ., 2016; Korsakova et al ., 2020). These data suggest that the eastern Lake Imandra depression deglaciated in the Allerød–Younger Dryas.…”

“…(2016) and Korsakova et al . (2020) suggested that the proglacial lake was followed by an extensive pre‐Imandra Lake basin in the Preboreal. In the early Holocene, its lake level lowered and isolated small lakes, e.g.…”