30,000 Years of the southwestern Lake Urmia (Iran) paleoenvironmental evolution inferred from mineralogical indicators from lake and watershed sediments

Ting Kong (1) , Alina Tudryn (1) , Elisabeth Gibert-Brunet (1) , Piotr Tucholka (1) , Seyed-Hani Motavalli-Anbaran (2) , Hesam Ahmady-Birgani (3) , Mohammad Lankarani (2) , Serge Miska (1) , Aurélie Noret (1) , Olivier Dufaure (1)

1 GEOPS - Géosciences Paris Saclay
2 University of Tehran
3 Urmia University

In order to understand the pattern and trends of the environmental evolution of Lake Urmia (Iran), one of the largest terminal lakes in Western Asia before its level drop over the past two decades, two sediment cores (Golman 6, 8.0 m; Golman 7, 12.5 m) were collected from the recently dried-out southwestern part of the lake. These sediment cores represent a continuous sedimentary sequence, composite core, that was extensively studied for grain size, total mineralogy including clay minerals, carbonates and their crystallinities, in comparison with the basin geological formations and within a reliable AMS-14 C timescale. Lake Urmia deposits cover the timespan from 30 to ca 2 cal kyr BP. Grain-size of the siliclastic fractions from the lower part of the composite core consists of fine-silt and clay particles likely representing lacustrine deposits while the top sediments are characterized by variable composition of sand and silt. At about 30 cal kyr BP, our proxies indicate a low lake stand and even drying out at the coring site, which was followed by water level rise and the establishment of lacustrine conditions between 29.9 and 20.2 cal kyr BP. Since then, all our data suggest lake's highly unstable conditions. Subsequently, clearly low lake levels to sometimes the drying out was recorded during the 20.2-15.3 cal kyr BP, 13.3-11.8 cal kyr BP and 5.6-4.1 cal kyr BP intervals. In contrast, lacustrine conditions were reestablished between 15.3 and 13.3 cal kyr BP, between 11.8 and 5.6 cal kyr BP and between 4 0.1 and 2.3 cal kyr BP. High water level recorded between 15.3 and 13.3 cal kyr BP can be attributed to the Bölling/Alleröd warming, and the following regressive phase during the 13.3-11.8 cal kyr BP period corresponds to the Younger Dryas period. In the Early-Mid Holocene, the lacustrine environment from 11.8 to 5.6 cal kyr BP was characterized by high aragonite and salt contents, highlighting evaporative environment as like during the 29.9-20.2 cal kyr BP period. Our results allowed the Late Quaternary climate reconstruction at Lake Urmia basin scale and record the past climate change at a larger Western Asia scale.

Mots clés: 14 C dating; Lake Urmia; Late Quaternary palaeoenvironments; Water level change; Carbonates; Clay minerals

Domaines: Minéralogie; Sciences de l'environnement

Ting Kong, Alina Tudryn, Elisabeth Gibert-Brunet, Piotr Tucholka, Seyed-Hani Motavalli-Anbaran, et al.. 30,000 Years of the southwestern Lake Urmia (Iran) paleoenvironmental evolution inferred from mineralogical indicators from lake and watershed sediments. Journal of Asian Earth Sciences, 2022, 239, pp.105387. ⟨10.1016/j.jseaes.2022.105387⟩. ⟨hal-03874560⟩