Utwory ordowiku, syluru i dewonu w Lubaniu (Sudety, Góry Kaczawskie)

Abstract

Przeprowadzono dokumentację paleontologiczną, stratygraficzną oraz próbę odtworzenia warunków sedymentacji łupków w większości ilasto-krzemionkowych, miejscami z fosforytami i wkładkami tufów, tufitów oraz diabazów. Stwierdzono wiele poziomów produktów wulkanizmu: kwaśnego w ordowiku oraz zasadowego w sylurze i dewonie. Zwrócono uwagę na związek radiolarii i fosforytów z wulkanizmem.ORDOVICIAN, SILURIAN AND DEVONIAN ROCKS AT LUBAŃ (KACZA WA MTS, SUDETY MTS)Since 1865, graptolite-bearing shales from Lubań were often dated at the Lower Silurian and,partly even lower part of the Lower Devonian. The studies carried out by the present authors showed that epimetamorphic series exposed in railway cutting at Lubań ranges in age from the uppermost Ordovician to upper parts of the Lower Devonian. inclusively. It was originally comprising politic and fine-clastic deposits with organogenic intercalations (radiolarites) as well as phosphatic nodules limited to some intervals of the succession. The share of diabases and diabase tuffs is fairly high here.The series originated in hemipelagic zone, characterized by low water turbulence and . affected by bottom currents. Bathymetric conditions could vary but sedimentation has always been taking place beneath the base of waving (700-1000 m). The enrichment of water and Sea-floor sediments in silica, connected with desilification of volcanic material. resulted . in development of radiolarians and siliceous deposits. The .desilification also resulted in origin of phosphatic nodules. Two types of such nodules, characterized by envelope-concentric and colomorphic structures, respectively were originating at two stages in development of deposits as syngenetic and early-diagenetic ones.Synsedimentary nature of volcanic phenomena is shown by the presence of tuffs and tuffites as well as traces of volcanic glass and single chlorite and biotite pyroclasts in the major part. of Ordovician, Silurian and Lower Devonian shales.The stratigraphic sequence (Fig. 1, Table I) and, partly, sedimentary conditions were reconstructed on the basis of analysis of paleontological material. Radiolarians, Acritarchs and Dinoflagellata are present almost in the whole section whereas graptolites and conodonts seem confined to some intervals only. Moreover, foraminifers, sponge spicules, annelids, styliolinids, trilobite exoskeleton fragments, remains of ostracodes, and algae, including rhodoliths were often found here.