An environmental magneto-lithogenetic study. II. Insights from surficial sediments

Abstract

Magnetic susceptibility (MS) represents a high resolution environmental and lithological (LITHO) proxy tool, which is successfully used for the study of recent sediments in freshwater or marine aquatic environments. The studies that we have achieved in the last 40 years in the Danube – Danube Delta – Black Sea hydrosedimentary system have revealed strong connections between the characteristics of sedimentary environment, sediment quality and their magnetic properties. In the present paper are discussed results concerning several lakes from Gorgova − Uzlina Depression (Danube Delta), which are added to the lately published magneto-lithological data for sedimentary environments of Meşteru − Fortuna and Matiţa − Merhei depressions. This work, which represents the first part of a composite paper, is particularly focused on the sediment cores collected in the lakes Gorgova, Cuibeda, Uzlina and Isacova. Their MS characterization, not neglecting the lithological support, defined by the three main components, namely the SILiciclastic/ minerogenic fraction – SIL, Total Organic Matter – TOM and CARbonates – CAR, is approached. Several lithological units are identified, based upon the macroscopic characteristics, magnetic properties and lithological composition. It is interesting to note that although the study area is included in the fluvial delta plain, the recent lacustrine sediments are very thin in some sectors and the short cores (under 60 cm) stop at a level of marine clays (L. Cuibeda). The second part of this study, regarding the surficial sediments from the above-mentioned lakes, and more other ones is published inside of a similar magneto-lithogenetic context. All these data give new evidences for demonstrating the availabilities of the method used to identify the environmental influences on the magnetic susceptibility of lake sediments, and hence to assess the geoecological state of the deltaic area under attention.