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Communication Dans Un Congrès Année : 2023

5,000 years of environmental change and anthropogenic impact deduced from gravity sediment cores from Lake Sevan, Armenia

M.L. Adolph
  • Fonction : Auteur
U Amelung
  • Fonction : Auteur
K Friese
  • Fonction : Auteur
H Hovakimyan
  • Fonction : Auteur
Kristina Sahakyan
  • Fonction : Auteur
Lilit Sahakyan
  • Fonction : Auteur
  • PersonId : 1127222

Résumé

Lake Sevan is located in eastern Armenia close to the border to Azerbaijan. With a length of ~70 km, a width of ~50 km at an altitude of 1900 m a.s.l. it is one of the largest freshwater high-mountain lakes. The lake itself is structured in two parts: the larger southern part called Big Sevan has a maximum water depth of 34 m whereas the northern smaller part called Small Sevan has a water depth of 65 m in the centre and a maximum water depth of 83 m close to the northern shore as a result of active tectonics. Up to now, only limited information exists about more distal profundal sediments from Lake Sevan. Studies, which have been carried out so far, focused on micropaleontological investigations such as ostracods or pollen. Chemical investigations let alone multi-proxy approaches have rarely been done. In order to explore the further potential of sediments from Lake Sevan we recovered 16 gravity cores (51-141 cm length) from both parts of the lake in October 2021. All cores are clearly characterised by a more homogenous sedimentation in the lower part of the core and a more diverse succession in the upper part, which can likely be attributed to intense water level regulations since Soviet times, and anthropogenic impact in the subrecent past. In addition to that, the longest recovered sediment sequence (SEV21-6; 141 cm length) is finely laminated in the bottom part. Radiocarbon ages on two cores from the centres of each lake part indicate a rather constant sedimentation rate since 5,000 cal BP in Big (SEV21-6) and 3,000 cal BP in Small Sevan. These chronologies are currently checked using paleomagnetic secular variation stratigraphy. Subsequently, they will be used in combination with a multi-proxy approach consisting of grain sizes, CNS, XRF-scanning and visible-spectrum scanning reflectance spectroscopy (VIS-RS) analyses as well as micropaleontological parameters (pollen, diatoms) for paleoenvironmental reconstructions.
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Dates et versions

hal-04170142 , version 1 (25-07-2023)

Identifiants

  • HAL Id : hal-04170142 , version 1

Citer

Torsten Haberzettl, M.L. Adolph, U Amelung, Ara Avagyan, K Friese, et al.. 5,000 years of environmental change and anthropogenic impact deduced from gravity sediment cores from Lake Sevan, Armenia. INQUA, Jul 2023, Roma, Italy. ⟨hal-04170142⟩
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