Loess-soil sequence at Toshan (Northern Iran): Insights into late Pleistocene climate change Stefan Vlaminck a, * , Martin Kehl a , Tobias Lauer b , Ali Shahriari c , Jafar Sharifi c , Eileen Eckmeier e , Eva Lehndorff d , Farhad Khormali c , Manfred Frechen b a Institute of Geography, University of Cologne, Albertus-Magnus-Platz, D-50923 Cologne, Germany b Leibniz Institute for Applied Geophysics (LIAG), Geochronology and Isotope Hydrology, Stilleweg 2, D-30655 Hannover, Germany c Department of Soil Sciences, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran d Institute of Crop Science and Resource Conservation, Soil Science and Soil Ecology, University of Bonn, Nussallee 13, D-53115 Bonn, Germany e Department of Geography, Physical Geographyand Geoecology, RWTH Aachen University, Templergraben 55, D-52056 Aachen, Germany article info Article history: Available online xxx Keywords: Loess Palaeoclimate Iran Palaeosol abstract The knowledge of palaeoclimate in Iran is still limited. However, insight into the timing and the dynamics of Quaternary climate change in Iran might offer valuable information to improve the global palae- oclimate record. The loess-soil sequence of Toshan provides the first high-resolution record of late Pleistocene climate dynamics in Iran and complements the hitherto known sections at Neka, Now Deh and Agh Band to establish a pedostratigraphic record of the north-eastern Caspian Lowland. Our spec- troscopic and grain-size analysis are combined to propose (i) a pedostratigraphical scheme for the sequence at Toshan, (ii) describe and estimate the degree of soil development of selected stratigraphical units, (iii) infer palaeoclimatic information, and provide (iv) a correlation with previous loess-palaeosol records of N-Iran as based on pedostratigraphic assumptions. The section at Toshan hosts a strongly developed reddish-brown argillic palaeosol (Bt) as well as eight moderately to weakly developed brownish palaeosol horizons lacking clay illuviation features (Bw/Bwk). These remnants of fossil soils are separated by finely textured loess and horizons that host characteristics of both loess and mineral subsoils (CB/CBk), giving evidence for syngenetic soil formation. The stratigraphical succession of palaeosols, loess and syngenetically altered sediments, covering the last ca. 130 ka, gives evidence for recurrent climate changes as well as fluctuations between dominance of soil formation or dust accu- mulation in relation to changes in moisture regime. The formation of Bt and Bw/Bwk-horizons is related to relatively humid and warm conditions likely corresponding with interglacial and interstadial climate. © 2015 Elsevier Ltd and INQUA. All rights reserved. 1. Introduction Loess deposits constitute a sensitive terrestrial archive, as their formation involves processes governed by climate such as the production and deflation of (mainly) silt-sized particles, their aeolian transport and deposition as well as syn- and post- depositional alterations (e.g. P ecsi, 1990; Kemp, 2001; Smalley et al., 2005). Traditionally the accumulation of dust forming loess is thought to occur mainly during cold and arid intervals of glacial periods (stadials) (Kemp, 2001). In contrast climatic conditions during interglacials and interstadials are characterized by higher average temperature and precipitation, which promoted the growth of vegetation, the intensity of chemical weathering and pedogenesis. Hence, under relatively stable geomorphodynamic conditions, soils formed on the dust covered landscapes of the past. Their burial under new layers of dust resulted in vertical succes- sions of loess layers and intercalated palaeosols often preserved as remnants of the original soil. The kind and intensity of soil forming processes are mainly driven by climatic and soil-environmental conditions. According to Jenny (1941), soil-formation is a function of climate, organic activity, relief, parent material and time, which is expressed by, e.g. the function S ¼ f(climate [cl],organic matter [o],relief [r],parent material [p]). Though afflicted with restrictions, palaeoclimatic inferences can be drawn from comparison of palaeosols with the modern (Holocene) soil, forming under known * Corresponding author. E-mail address: vlamincs@uni-koeln.de (S. Vlaminck). Contents lists available at ScienceDirect Quaternary International journal homepage: www.elsevier.com/locate/quaint http://dx.doi.org/10.1016/j.quaint.2015.04.028 1040-6182/© 2015 Elsevier Ltd and INQUA. All rights reserved. Quaternary International xxx (2015) 1e14 Please cite this article in press as: Vlaminck, S., et al., Loess-soil sequence at Toshan (Northern Iran): Insights into late Pleistocene climate change, Quaternary International (2015), http://dx.doi.org/10.1016/j.quaint.2015.04.028