THE LANDSCAPE EVOLUTION OF THE LAUSITZ MASSIF – RESULTS FROM NEOVOLCANIC EDIFICES FROM THE LAUSITZ VOLCANO FIELD (EASTERN GERMANY)

Three Cainozoic volcanoes (Baruth, Landeskrone, Sonnenberg) were investigated in the Lausitz Volcano Field (climax 30-25 Ma) for the reconstruction of the uplift and denudation history in a consolidated area. The volcano remnants mark and save the synvolcanic paleosurface.

The Baruth Complex Volcano is situated in the northern Lusatia and contents of three deeply eroded scoria cones. Only in glaciofluviatile Saalian-1-Glaciation sediments appear greater amounts of scoria pebbles in this place. This suggest greater scoria bodies for the 33-27 Ma old volcanoes at the time about 250 000 years ago. Such observation implies a young uplift of the Lausitz Massif.

The Landeskrone Volcano also gives indications for neotectonic movements. The reconstruction of this large monogenetic scoria cone in the eastern part of the Lausitz massif allows in connection to adjacent volcano edifices the estimation of an average denudation rate from 3 mm / ka for the last 34 Ma. Probably, this uplift and denudation rate increased in the upper Middle Pleistocene. Otherwise, the recent 200 m high basaltic hill would destroyed by the overriding of two Elster glacial ice streams. Furthermore, a 28 km long geomorphologic N-S profile which incorporated 7 additional volcano edifices, showed a tectonic differentiation between uplift and subsidence areas inside of the Lausitz Massif in the last 30 Ma. A rigid and en bloc movement of this Variscan Basement unit can be excluded.

The Sonnenberg Volcano is situated in the Elbe Zone 1.3 km southward the Lausitz Fault. On this fault the Lausitz Massif is uplifted up to 1000 m against the Elbe Zone. This elevation direction got an inversion to synvolcanic time; therefore today the Zittauer Gebirge Mountains overtop the Lausitz Massif by 200 m. In contrast, the Sonnenberg Volcano (30-27 Ma) and the adjacent volcanic edifices show little erosion. Therefore, the maximal 50 m deep erosion of the Zittau Mountains should also be induced by a young uplift with a rate of 7 to 10 mm / ka.

In further, it is planed to investigate about 50 volcanoes of the Lausitz volcanic field and make a 2D and 3D modelling. The volcanological study of neovolcanoes represents a helpful tool for the uplift and denudation history for the last 30 Ma and completes the results of the fisson track data (85-50 Ma) and the Upper Pleistocene deposit investigations.