On loess deposits of northern Iran
Subject Areas : Geopolitic
مارتین
Kehl
1
(ندارد)
M.R
Sarvati
2
(ندارد)
Hassan
Ahmadi
3
(ندارد)
Manfred
Frechen
4
(ندارد)
آرمین
Skowronek
5
(ندارد)
Keywords: loess-paleosol sequences, northern Iran, past climate change, Pleistocene,
Abstract :
In the southern lowlands of the Caspian Sea and its vicinity, loess is found in differentgeomorphological settings along a pronounced climatic gradient. The loess depositsare often intercalated by different types of paleosols. So far, little information has beenpublished about the nature, origin and age of the loess-paleosol sequences in NorthIran.This paper describes five loess-paleosol sequences exposed in the Sefid-Rudvalley (sections at Rustamabad and at Saravan), on the northern foothills of Alborz(sections at Neka and at Now Deh) and in the loess hills of Golestan province (sectionat Agh Band). The Sefid-Rud loesses are characterised by large textural variations on alocal scale. Angular slope debris and distorted paleosols in the clayey loess deposit atthe section at Rustamabad testify displacement by slope processes, which wastriggered by climate change and/or tectonic impacts. At the section at Saravan, loess isintercalated by two brown paleosol horizons which might correlate with OIS 3.At the section at Neka, two strongly developed brown paleosols (Btk or AhBtkhorizons) are intercalated in clay-rich loess. First luminescence age estimates indicatethat the upper paleosol was formed during OIS 5a-5d. Eight light or dark brownpaleosols (Bwk and Btk horizons) are intercalated in the loess at the section at NowDeh indicating different weathering intensities most likely during the Middle andUpper Pleistocene. In the loess hills near Agh Band, 40 m thick homogenous loesscovers a brown paleosol, possibly correlating with the last interglacial soil.The loess-paleosol sequences at the sections at Neka, at Now Deh and at AghBand are excellent terrestrial archives of Quaternary climate and environment changein northern Iran