Time filter

Source Type

Sztano O.,ELTE TTK Altalanos es Alkalmazott Foldtani Tanszek | Magyari A.,Magyar Allami Foldtani Intezet | Toth P.,ELTE TTK Altalanos es Alkalmazott Foldtani Tanszek | Toth P.,Schlumberger
Foldtani Kozlony | Year: 2010

The main objective of this study is to determine the depositional mechanisms, the environment and controlling factors producing the architecture of the Kálla Gravel, which unconformably overlies the SW rim of the Transdanubian Range. The gravel crops out in large, actively quarried and small abandoned pits near to Lesenceistvánd and Uzsabánya. Three main architectural units can be distinguished based on facies, dip of strata and surfaces of toplap, downlap and/or erosional truncation. The lowermost 4-15 m-thick unit is built up of 0.2-0.8 m thick, steep (20-30°), southward dipping beds of clastsupported gravel or sandy gravel. Pebbles commonly show a(t)b(i)-type imbrication. The facies of the middle units are the same, but their respective thicknesses vary between 1-5 m and show significantly different dip directions towards N, NE. The uppermost unit is made up of horizontally-bedded sand, pebbly sand and sandy pebble. The steeply-dipping gravelly units are interpreted as foresets of a shallow-water, Gilbert-type delta prograding - in the case of the thick, lower unit - southward, and for the middle units strangely sideward to north-east. The horizontal beds of the upper unit were deposited on the flat-lying delta-plain. These units represent different phases of delta development. The lowermost units reveal the first step of a relative lake-level rise, followed by deltaic progradation due to a high rate of sediment input. The upper unit is mainly aggradational, indicating continued lake-level rise; the latter was again balanced by sedimentation. Although many small-scale deformational structures (slumps, slides, dewatering) can be seen, these are connected to rapid deposition. Evidence of synsedimentary faulting has not been exposed so far. Therefore the reconstructed, relative lake-level changes are interpreted as an indication of basin-wide subsidence combined with climatically induced (increased humidity) water-level rise.

The mineralogical and petrological characteristics of Mars could be ingrated into the general surface evolution of theplanet with the methods of classical geology on the Earth. Basaltic rocks cover the southern, while andesitic or weatheredbasalts cover the younger northern hemisphere. The cooling and drying Martian environment produced phyllosilicatesunder relatively warm and wet conditions in the early period of the planetary evolution. Later cold and acidic episodicwater produced sulphates, and their crystal water content is keep on changing according to the climatic changes. Duringthe longest and most recent period ephemeral microscopic water films, and dry gas-mineral interactions produced various iron-oxides and oxihydroxides. Other mineral alterations point to the presence of ancient hydrothermal systems,migrating mobile elements, and cementation of the regolith's topmost layer. The differently aged primary and secondary minerals can be found together in mixed form inside the regolith, because of the lack of global plate tectonism and the slower speed of geologic changes on Mars than on Earth.

Loading ELTE TTK Altalanos es Alkalmazott Foldtani Tanszek collaborators
Loading ELTE TTK Altalanos es Alkalmazott Foldtani Tanszek collaborators