Proceedings of the 12th International INQUA meeting on paleoseismology, active tectonic and archaeoseismology

400 PATA Days 2024 Sangiyn Dalai Lake This lake can be divided into two sub-lakes that are interconnected by a natural channel. The south-side lake is surrounded by gentle topography and the bathymetry shows local depocenters along the central area of the lake. These depocenters have a depth ranging from 7 to 7.5 meters and are characterized by long wavelength topographic changes. On the north-side lake, on the contrary, steep topography and vertical escarpments border the south shoreline and partially the northern side. Cores Lake6-23-01 and 02 are quite homogeneous and consist of mud, core Lake6-23-03 contains a 1.2 cm thick layer of coarser material (fine sand) and the XRF signature shows an upward decrease of silicates within such layer, probably related to a normal grading arrange. Fig. 3: Sedimentary cores from Oygon Lake. Well- preserved and clearly defined stratification. Green foam indicates the location of sampling for thin-section preparations. This core is the best candidate to track past earthquakes in the south-side lake. On the other hand, core Lake6-23- 04, from the north-side lake, displays an alternation of muddy and silty layers with colors ranging from whitish grey to dark brown between 27 and 78 cmof depthwithin the core. Then, from 79 cm down to the bottom of the core, a strong change in the sedimentary facies is defined by the deposition of Ti-rich middle grey sandy layers with a high content of organic material. The sedimentary layers of this core span over the last ~6kyr and age models show a sedimentation rate of 0.11 mm/yr at the core site, located in the depocenter of the lake (22.6 m). Such sedimentation rate is almost half that at the south-side lake from the Lake6-23-03 core (0.27 mm/yr). Fig. 4: XRF silicates (Al, Si, K) and Ti profiles of Lake4- 23-01 core. Black arrows point to distinctive peaks likely related to turbidite deposits. The first arrow from up to down very likely corresponds to the signature of the 1905 M8 Bulnay event.