О ПАЛЕОЭКОЛОГИЧЕСКОЙ ЦЕННОСТИ КОЛЛЕКЦИЙ НИЖНЕФРАНСКИХ БЕСПОЗВОНОЧНЫХ ГЛАВНОГО ДЕВОНСКОГО ПОЛЯ В ФОНДАХ ГОРНОГО МУЗЕЯ

Abstract

The article describes two groups of facies most widely represented in the collections of Lower Frasnian invertebrates of the Main Devonian Field in the Mining Museum (hardgrounds and pelecypod banks). The presence of three types of hardgrounds has been established, differing in the nature of the original bottom and the time of exposure of each hardground, and hence structural and textural features of rocks and systematic composition of oryctocenoses. The first type is crinoidal limestone with an extensive complex of sclerobionts and traces of bioerosion by Trypanites Mägdefrau, an uneven surface and a visually almost complete absence of impregnation. In hardgrounds of this type, three generations of sclerobionts are distinguished, namely: abiogenic substrates (first), incrustators of the remains of organisms of the first generation (second), and bioerosion organisms (third). The second type is micritic limestone with a smooth glass-type surface, a small complex of sclerobionts and traces of bioerosion by Trypanites Mägdefrau. The third type is pelecypod limestones with an uneven surface, isolated sclerobionts, numerous traces of bioerosion by Trypanites Mägdefrau and strong ferruginous impregnation. For the most widespread hardgrounds of the first type, the presence of specific taphofacies has been established, characterized by good preservation of organic remains of the first generation, an almost complete absence of organic remains of the second generation, and a complete absence of bioerodible organisms. The appearance of such taphofacies is due to the short exposure time of the hardground and the beginning of a rapid process of new accumulation immediately after the appearance of the first organisms of the second generation. The presence of such taphofacies emphasizes the importance of distinguishing taphofacies in certain paleofacies and certain types of oryctocenoses. In the oryctocenoses of pelecypod shells, three morphological and ethological types of cornulitids have been established. The most representative settlements of cornulithids were characteristic of calcareous clay soils with small areas of compacted bottom.