TY - JOUR

T1 - Lake systems in mountain borders of the Great Lakes Basin of Mongolia

T2 - From Pleistocene catastrophes to Holocene gradual evolution (case study from southwestern Tuva)

AU - Agatova, A.R.

AU - Nepop, R.K.

AU - Glebova, A.

PY - 2020/2/10

Y1 - 2020/2/10

N2 - The paper presents results of integrated geological, geomorphological, geochronological, and geoarchaeological studies in the basin of Lake Ak-Hol located in southwestern Tuva (Russia), in mountains north of the Great Lakes Basin of Mongolia. The Pleistocene-Holocene history of the basin consisted of several stages recorded in terrain and deposition patterns. The highest stand of Lake Ak-Hol (180 m above the present level and 16 times greater area) was due to an ice dam and was coeval to the appearance of organic matter (remnants of higher aquatic plants and algae) in lake sediments about 14 ka cal BP. At the next stage, the lake was impounded by a moraine dam. 14C ages of buried soils indicate that the level of the ice- and moraine-dammed lake fell to below 222 m asl long before 8.5 ka cal BP. Erosion of the moraine dam may correspond to the event of lake drying about 12 ka cal BP evident from a deposition gap in sedimentary cores. That event of sudden drainage may have been the last catastrophic flood into the Great Lakes Basin traceable in the catchment of the Mogen-Buren River. Judging from the obtained 14C ages of sediments from the Mogen-Buren Valley, ice- and moraine-dammed lakes in the Ak-Hol system underwent cataclysmic outburst floods only before 11.6 ka cal BP. In the Holocene, after the moraine dam failure, the lake level changes were controlled solely by climate. The general decreasing trend was repeatedly interrupted by high stand excursions (up to 15 m of relative level rise). Nomad peoples settled on the floor of the highland Ak-Hol basin since the Late Bronze Age. All archaeological sites (from that time to the time of Turkic cultures) mapped in the basin are located above 2220 m asl and lack signatures of water erosion, indicating that the lake never rose above that altitude for the past 3 ka years.

AB - The paper presents results of integrated geological, geomorphological, geochronological, and geoarchaeological studies in the basin of Lake Ak-Hol located in southwestern Tuva (Russia), in mountains north of the Great Lakes Basin of Mongolia. The Pleistocene-Holocene history of the basin consisted of several stages recorded in terrain and deposition patterns. The highest stand of Lake Ak-Hol (180 m above the present level and 16 times greater area) was due to an ice dam and was coeval to the appearance of organic matter (remnants of higher aquatic plants and algae) in lake sediments about 14 ka cal BP. At the next stage, the lake was impounded by a moraine dam. 14C ages of buried soils indicate that the level of the ice- and moraine-dammed lake fell to below 222 m asl long before 8.5 ka cal BP. Erosion of the moraine dam may correspond to the event of lake drying about 12 ka cal BP evident from a deposition gap in sedimentary cores. That event of sudden drainage may have been the last catastrophic flood into the Great Lakes Basin traceable in the catchment of the Mogen-Buren River. Judging from the obtained 14C ages of sediments from the Mogen-Buren Valley, ice- and moraine-dammed lakes in the Ak-Hol system underwent cataclysmic outburst floods only before 11.6 ka cal BP. In the Holocene, after the moraine dam failure, the lake level changes were controlled solely by climate. The general decreasing trend was repeatedly interrupted by high stand excursions (up to 15 m of relative level rise). Nomad peoples settled on the floor of the highland Ak-Hol basin since the Late Bronze Age. All archaeological sites (from that time to the time of Turkic cultures) mapped in the basin are located above 2220 m asl and lack signatures of water erosion, indicating that the lake never rose above that altitude for the past 3 ka years.

KW - Ak-Hol basin

KW - Dammed lakes

KW - Landscape evolution

KW - Late Pleistocene-Holocene

KW - Outburst floods

KW - SW Tuva

UR - http://www.scopus.com/inward/record.url?scp=85054151403&partnerID=8YFLogxK

U2 - 10.1016/j.quaint.2018.09.013

DO - 10.1016/j.quaint.2018.09.013

M3 - Article

VL - 538

SP - 53

EP - 62

JO - Quaternary International

JF - Quaternary International

SN - 1040-6182

ER -