Zagadnienie śródkarbońskich dyskordancji w północno-zachodniej części niecki śródsudeckiej

Abstract

THE PROBLEM OF INTRA-CARBONIFEROUS DISCORDANCES IN THE NORTH-WESTERN PART OF THE INTRA-SUDETIC TROUGHSummaryThe article deals with the problem of the relation between the Upper and Lower Carboniferous formations in the north-western part of the Intra-Sudetic depression. Towards the east, the area under discussion joins the Wałbrzych Coal Basin, in which a somewhat different facial development and greater thickness are observed. A comparison of the Carboniferous series in both areas forced some geologists to accept the presence of the Intra-Carboniferous discordance in the area considered.The present author (K. Dziedzic, 1960, 1961) already earlier pointed to a continuous sedimentation in this area, similarly as in the Wałbrzych Coal Basin. According to this author the differences in the development of the Carboniferous series were a result of specific structural character of either region and not due to discordance. The Wałbrzych region reveals some features of a basin, whereas the western one discloses certain properties of piedmont area. The Wałbrzych region that embraces the Wałbrzych Coal Basin and the adjacent areas was an early Hercynian structure of crypto-volcanic origin (K. Dziedzic, 1966).At the late Devonian time, the Wałbrzych Coal Basin developed within this structure. It was formed due to a mechanism of cauldron subsidence type. In the Lower Carboniferous period, the basin was long influenced by marine conditions. In the Upper Carboniferous, however, a rich boggy-marshy subfacies developed. In the western region of piedmont type, coarse-elastic alluvia predominated. The boggy-marshy or fine-grained subfacies was restricted to the riverside overflood plains only. Stream and torrent deposits are here a prevailing type of formations. The examinations point also to the existence of meandering streams and to the migration of river channels.