DBPapers

STRUCTURE AND EVOLUTION OF COLLAPSIBLE DEPOSITS EAST OF BUCHAREST OF THE MOSTIŞTEA PLAIN, ROMANIA

AUTHOR/S: AL. ISTRATE, M. FRINCULEASA
Sunday 1 August 2010 by Libadmin2010

10th International Multidisciplinary Scientific GeoConference - SGEM2010, www.sgem.org, SGEM2010 Conference Proceedings/ ISBN 10: 954-91818-1-2, June 20-26, 2010, Vol. 1, 305-312 pp

ABSTRACT

Sedimentation of loess deposits in southern, southeastern and eastern Romanian Plain is
a consequence of developments in Romanian Carpathian chain and the outer rigid
platforms based on global climate changes, which have succeeded in the Quaternary
period. The Loess deposition took place in at least two interglacial stages, the last one
took place at the end of the upper Pleistocene, when is finalized, mostly the Romanian
Plain relief.

Mostiştea plain is situated at east of Bucharest; the area is bordered by rivers
Dâmboviţa, in southwest, and Mostiştea, in north-east, where is forming a tabularlooking
field with inflexions of the surface, sometimes with high amplitude. The
depression areas, where they were installed, often, lake systems, they are a reflection of
the characteristics of the loess deposits to settle under their own weight in water load.

From land investigation and laboratory analysis results vertical structure and evolution
of loess deposits.Relatively uniform granular structure shows that the main factor is the
eolian transport and sedimentation, the glacial deposits of the Carpathians being the
sediment source.

The sequence is separated vertically into two subareas with different behavior on the
property of settlement by wetting. Thus, the surface retains the property to settle
relatively suddenly the effect of vertical water infiltration, while the bottom subarea has
lost this property. This results from the vertical distribution of calcium carbonate and
the physical and mechanical properties determined by laboratory tests.

From macroscopic observation the processes that are evident are calcium carbonate
dissolution in their top and precipitation to bottom. This means, that in time, the subarea
has evolved in a relatively constant intake of water which have reworked the carbonates
towards the bottom and produced the settlement of loess deposits under its own weight.
Perhaps this lower subarea evolved in wet weather conditions that keep excess moisture
from the ground surface.

Keywords: wetting-sensitive deposits, collapsible deposits, settlement by wetting, lacustrine sedimentation basin, sedimentation and eolian transport