Writers : N. Khadem
Refference : Geosciences Scientific Quarterly Journal,No.:15-16,P.:90
Publishing Year : 1374

Abstract :

This paper deals with new data on the formation of stratified, homogeneous alluvial sediments (second group on the classification in the introduction) and stratified screes, occurring in Velenjack area, being based on 1993 field- investigations.

The stratified screes of Velenjack, is in fact stratified slope deposits, which have been formed in a periglacial climatic condition. The active and fosil examples have been reported from various parts of the world.

The classification adopted here under the name "stratified, homogeneous alluviums" is in fact a kind of formation mentioned above andis formed in the down stream slope. In the upper reaches of this formation, the rocks become disintergrated as a result of freezing and defreezing of ice, which ultimately is carried away downwards by gravitational forces. The latter deposit may become stratified or laminated and may travel approximately 2 to 3 km.

The writer is of opinion that the stratified, homogeneous alluviums are deposited onto the slopes during

the periglacial condition and they are intimately associated with conglomerate and shale. An example of this may be observed in the largest slope along the course of the above- mentioned formation, in the southern flank of an anticline extending from west of Abbas Abad to Baghe Feiz with more or less an east- west trend. In order to have access for further evidences on the formation of slope deposits, the writer has benefitted greatly from various reference works of French CAEN and C.N.R.S., in particular the papers of J. C. Ozouf.

It should be reminded that, the imprints of the Quaternary Glaciation in the Central Asiatic regions, including Iran, were nothing like those encountered in -the western Europe and North America. This is due to remoteness from oceans and local climatic conditions, as well as being away from rain- producing front; consequently large scale glaciation is absent. However, only locally in the high mountains and deep valleys some glaciations occurred. But evidently, Alborz Range did not possess its present altitude then. Hence, no confirmed glaciation is reported from the region. But, the world drop in temperature, also included Iran as well.

Subject List : , Alluvial deposites