Morphoevolution of the Seymareh landslide-dam lake system (Zagros Mountains, Iran): Implications for Holocene climate and environmental changes

The Seymareh landslide is the largest rock slope failure (44 Gm3) ever recorded on exposed Earth surface. It detached at ∼10 ka from northeastern flank of Kabir-Kuh anticline (Zagros Mountains, Iran) creating a natural dam responsible for formation lake system that persisted ∼3 kyr during early and mid-Holocene before its emptying phase caused by overflow. chronology demise connection to Holocene climate variations have been barely studied. To reconstruct influence local vs. regional environmental changes upon history unravel their contribution overflowing phase, we analyzed 13 samples extracted 30-m-thick lacustrine succession belonging Lake. We performed grain size analysis, carbon oxygen stable isotopes carbonate-bearing sediments, X-ray diffraction analysis clay minerals, in addition geomorphological morphoevolution. Main results highlight infilling was characterized first period (from 9.73 ± 0.13 7.37 0.73 ka) with median sedimentation rate ~2 cm yr−1 second 6.98 0.39 marked an increased up ~10 yr−1. age here considered as termination beginning new valley entrenchment. Stable isotope analyses confirm humid interval after early-mid arid transition, consistent other regions Middle East. During this rainfall seasonality inter-annual irregularity may prevented development widespread vegetation cover likely favored increase denudation rates hillslopes sediment supply along connected channels network. Therefore, within downstream basin. However, late ~7.6–7.32 ka, high energy hydroclimatic events, sand content low δ18O concentration, were more frequently. This could justify sudden tributaries' discharge culminated ~7.3 because complete overflow Jaidar Lake into causing entire landslide-dam system.