Search Results

You are looking at 1 - 2 of 2 items for

  • Author: Igor Obreht x
Clear All Modify Search
Open access

Ian Smalley and Igor Obreht

Abstract

Loessification is a process by which a body of non-loess ground is transformed into a body of loess ground. The history of loessification is one of controversy and confrontation, largely because of mutual misunderstandings between geologists and pedologists. Lev S. Berg is the ‘only begetter’ of the theory, first proposed in 1916, and propagated throughout his life. R.J. Russell proposed the same approach to the loess in the Lower Mississippi valley in his famous 1944 paper, which contributed enormously to the study of loess in North America. As understanding of the various processes involved in the formation of loess deposits has developed, a compromise position on loess formation has become possible. The major intrinsic features of loess deposits are the open structure and the collapsibility. It appears that the open structure is caused by aeolian depositional processes and the collapsibility is caused by loessification processes. The compromise was initiated by Marton Pécsi in 1990, He endeavoured to retain a loessification aspect in the study of loess deposits, as the subject appeared to be overwhelmed by the aeolian idea system promoted by geologists; it has been mostly a Central European endeavour. The history of the concept of loessification largely involves (1) its development in Russia, (2) its dissemination and discussion – and attempts at refutation and modification – in the wider world.

Open access

Janina Bösken, Nicole Klasen, Christian Zeeden, Igor Obreht, Slobodan B Marković, Ulrich Hambach and Frank Lehmkuhl

Abstract

A new geochronology was established for the Stalać loess-paleosol sequence (LPS) in Serbia. The section is located in the interior of the Central Balkan region, south of the typical loess distribution, in a zone of paleoclimatic shifts between continental and Mediterranean climate regimes. The sampled sequence contains four well-developed paleosol and loess layers, a crypto tephra and one visible tephra layer. Optically stimulated luminescence measurements showed a strong dependency of preheat temperature on equivalent dose for one fine-grained quartz sample, which makes it unsuitable for dating. A firm chronology framing the last two glacial cycles was established using fine-grained polyminerals and the post-infrared infrared stimulated luminescence (pIR50IR290) protocol instead. The characteristics of dated paleosols indicate similar climatic conditions during the last interstadial and interglacial phases, which were different from the penultimate interglacial period. The tephra within the L2 loess, probably related to tephra layers also found in other sections in Southeastern Europe, was sandwich-dated. The results indicate an age between 118 ka and 141 ka. Furthermore, a weak pedogenic layer dated to between 126 ka and 148 ka gives a first numerical age to this soil formation in Southeastern Europe.