Szekessy Vilmos (szerk.): A Magyar Természettudományi Múzeum évkönyve 57. (Budapest 1965)
Csalogovits, I. J.: Geological and petrological conditions of the Szanda - Bercel area
ANNALES HISTORICO-NATURALES MUSEI NATIONALIS HUNGARICI Tomus 57. PARS MINERALOGICA ET PALAEONTOLOGICA 1965. Geological and Penological Conditions of the Szanda — Bercel Area By I. J. CsALOGOviTs, Budapest Summary: The Szanda-Bercel area, situated at the contact of the denuded remains of slip volcanoes — characterisitc of the geological structure of the Central Cserhát range — and the eastern adjoining overlying volcanic unit which had faulted along the NNE — SSW large-structural line and had undergone no erosion, is volcanologically of a central location. In addition to the formations of varied deposition and type of tertiary pyroxene-andesite volcanism, the diversity of the Chattian-Lower Miocene (Burdigalian-Helvetian) sediments is represented by the basic and cover formations of the Lower Miocene coal deposit series at Becske. It can be proved that the coal deposit series with gravel layers in its top, described by NOSZKY, SR., as being Helvetian, is actually of the Burdigalian stage and that its facies is similar to that of the ,,spread-bed" occurring in the Salgótarján basin. The changes of material in the vulcanites that had come to the surface in the course of pyroxene-andesite volcanism were caused by differences connected with forms of bedding. Contact phenomena concomitant of cooling, subsequent major hydrothermal effects and, finally, weathering have caused additional diversification of the rock. Of special importance are the diversified types and relatively large messes of hydrothermal formations that have not been described in the course of investigations so far. Boundaries and geomorphological structure of the area The boundaries of the 1:10 000 scale geological mapping of the area — about 35 square kilometres — are these : the northern slope of the Délkút-Szanda-Pereshegy range in the north; the Becske-Bercel highway in the west; the southern slope of the Istenhegy-Piskőhegy range in the south; and the N-S co-ordinate line extending westward from Bercel in the east. The morphological articulation between the Szanda and Pisköhegy dike is caused by the units built up of the cap debris of Mt. Bercel and Mt. Szép that adjoins the former structurally. After the cooling of pyroxene-andesite lava breaking through the Chattian and Burdigalian series, the dike-slip volcano structures that form the bottom of the cover were separated by erosion from the loose, sandy, clayey country rock as a sharp mountain ridge. Thus the morphological character of the area is clearly determined by the volcanic bodies. The side valleys developed on the andesits crests indicate hydro-andesitic belts that are less resistant because of hydrothermal decomposition. Stratigraphie conditions 1. The Upper Oligocène Chattian stage. No older formation than the Upper Oligocène was found in the area. The formations of the Chattian stage are made up of sandy, clayey sediments. 3 Természettudományi Múzeumi Évk. 1965.
