The Late Quaternary Tectono-Stratigraphic Evolution of the Lake Van, Turkey

Abstract

Many of the terraces around the Lake Van record a relatively short period of the much longer geological history of the Lake Van Basin. Their deposition took place during the last ca. 125 ka BP. They accumulated in a large array of shallow lake and lake margin environments, such as alluvial fan/braided river, beach, Gilbert-type delta, nearshore lake and offshore lake. Variability of their lithofacies provides evidence for climatic and tectonic controls of their depositional conditions. During their deposition high relief areas in the watershed delivered abundant detritus to the coastal areas of the lake. The sedimentation was therefore dominated by terrigenous clastic deposits. The highest concentrations of the coarse clastic sediments were at the mouths of the major streams where they formed Gilbert-type deltas. These river-dominated lacustrine deltas formed during rising lake levels and are relatively more abundant and thicker in the eastern margin of the lake, indicating that this margin mostly had a low-energy coast sheltered from the prevailing westerly winds. However, some areas of the same margin adjacent to deltas were also supplied with sediments by waves and storm-induced longshore currents to form beaches. Storms and storm-generated traction currents were perhaps active agents along the shores of the Lake Paleo-Van as suggested by the presence of the coarse-grained material in its nearshore facies. Somehow, during times of lake highstands, turbidity currents seem not to have played an important role in the sediment transportation along the lake margin, because the nearshore sediments hardly show any evidence of turbidite depositon, such as graded bedding and sole-marks. The offshore lake was relatively quite standing water, depositing laterally persistent, thinly-bedded to varved and fine-grained sandstones and mudstones in part with hydroplastic disruptions, such as slumps and convolute beddings. Because of the lack of sufficient datings of the terrace sequences around Lake Van, we cannot correlate them unequivocally. However, the absence of large-scale cyclicity within a given terrace sequence in each locality suggests that deposition of each terrace occurred during a separate lake level fluctuation each reaching to higher level than the modern lake level followed by a regression. The available age data suggest that high lake levels, reaching up to 1760 m asl, occurred during the last interglacial (MIS 5; 123-71 ka BP), 26-24 ka BP, 22-21 ka BP and 10-6 ka BP. The younging of the terrace deposits along with the decrease in elevation suggests either a gradual decline of lake level with time, or the effect of the cumulative uplift with time or both. The fluctuating lake level was probably due to a combination of climatic, volcanic and tectonic processes. Considering the hydrologically closed nature of the lake, climate probably played more important role than the others. Since the formation of the youngest terrace sediments of 6 ka BP, perhaps the climate in the basin has been mostly relatively more ar...

Porewater salinity reveals past lake-level changes in Lake Van, the Earth’s largest soda lake

“…The ICDP PaleoVan drill site at Ahlat Ridge is indicated by a white star. The spatial distribution of the terraces indicating past high lake levels 9 – 11 (black rhomboids) agrees well with the area of maximum extension of Lake Van during MIS5e and MIS7. The maps of both panels of Fig.…”

“…Past lake-level changes with respect to the present lake level of 1645 m above sea level (a.s.l.) have been reported in studies of lake terraces on land 8 – 11 ; in seismic 12 , 13 , volcanological 14 , and sedimentological 15 studies; and in studies of the geochemistry of the uppermost 10 m of the sediment column 3 , 16 , 17 .…”

Structural characteristics of the Lake Van Basin, eastern Turkey, from high-resolution seismic reflection profiles and multibeam echosounder data: geologic and tectonic implications

“…1). Volcanic rocks cover extensive areas, especially to the north and west of Lake Van (Wong and Finckh 1978;Litt et al 2009;Sumita and Schmincke 2013;Görür et al 2015). Eocene-to-Pleistocene clastic sediments and Upper Cretaceous carbonates crop out east of the lake (Wong and Finckh 1978;Görür et al 2015).…”

Van Gölü Bölgesi̇nde 2011 Yili Depremleri̇ni̇n Artçi Şok Seri̇si̇ Kirilma Karmaşiğina Yapisal Bağlanti(doğu Anadolu, Türki̇ye)

“…The analyses, in this paper, of the structural coupling to the Van aftershock sequence are often associated with mapped faults in the Lake Van Basin (Fig. 5) Toker and Şengör, 2011;Çukur et al, 2013;Çukur et al, 2016;Görür et al, 2015;Özalp et al, 2016;Toker et al, 2017;Toker, 2017). The joint interpretation of aftershock sequence and seismic reflection profiles reveals the lateral and vertical heterogeneity of the faultcontrolled aftershock distribution and along-strike seismic activity in crust within the rupture area.…”

“…The rupture gradually expanded near the hypocenter and was shaped in a sigmoidal-like propagation (Figure 1). It is thought that the earthquake occurred as a result of a long-term high plateau uplift (Görür et al 2015) and an eastward oblique tectonic extrusion of the Lake Van basin (Toker and Şengör 2011;Toker and Ecevitoğlu 2012a, b;Toker, 2017;Toker et al, 2017). Toker, M., (2021).…”