ЗАВИСИМОСТЬ РОДОВОГО СОСТАВА ОТРЯДА ATAXOPHRAGMIIDA (ФОРАМИНИФЕРЫ) ОТ УСЛОВИЙ ОБИТАНИЯ

• Main Author: Подобина, Вера
• Format: Text
• Language: unknown
• Published: Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Национальный исследовательский Томский государственный университет" 2011
• Subjects: РОДЫ ATAXOPHRAGMIIDA; ОБИТАНИE; СТЕНКА РАКОВИН; Arctic; Arctic Ocean; Foraminifera*; Lomonosov Ridge; Siberia
• Online Access: http://cyberleninka.ru/article/n/zavisimost-rodovogo-sostava-otryada-ataxophragmiida-foraminifery-ot-usloviy-obitaniya; http://cyberleninka.ru/article_covers/14010799.png

Изучены некоторые западносибирские роды отряда Ataxophragmiida и показана зависимость их морфологических признаков от условий обитания. Установлены так называемые роды-«двойники», внешне сходные, поэтому их ранее относили к общим родам (Gaudryina и Gaudryinopsis). Они имеют разный химический состав стенки (известковый или кварцево-кремнистый) и поэтому являются отличающимися родовыми таксонами. Studies on the West-Siberian genera of the Ataxophragmiid Order indicated the dependence of their generic composition on dwelling conditions. The obvious confinement of these taxa to transgressive stages of the basin was revealed. The primitively arranged forms prevailed during regressions. Agglutinated tests of more advanced foraminifers of the Ataxophragmiid Order are considered, which have test walls of diverse chemical composition. From the carbonate facies, the tests were encountered whose agglutinate was composed of calcite grains fastened with carbonaceous cement. Within terrigenous non-calcareous or siliceous clays, tests often possess quartz-siliceous walls. When analysed in detail, tests of the genera established previously as common proved to be distinct because of the diverse chemical wall composition. The author distinguished three pairs of the twin genera from the Ataxophragmiid Order: Verneuilina dOrbigny, 1840 Verneuilinoides Loeblich et Tappan, 1949 Gaudryina dOrbigny, 1840 Gaudryinopsis Podobina, 1975 Marssonella Cushman, 1933 Arenogaudryina Podobina, 1975. These twin genera are illustrated on the palaeontological plate. The twin genera Gaudryina dOrbigny, 1840 and Gaudryinopsis Podobina, 1975 have been studied, which are known from the Mesozoic  Palaeogene deposits of Western Siberia and confined to the peaks of transgressions. These deposits, excluding the Gankinskaya Suite, are composed of terrigenous, non-calcareous clays with embedded forms of the Gaudryinopsis Podobina, 1975 Genus possessing quartz agglutinate in the structure of test walls. In the Gankinskaya Suite composed of calcareous siltstones and clays, the Gaudryina dOrbigny, 1840 Genus has been encountered its test walls contain calcite grains as agglutinate. These two genera were also found to be morphologically distinct. In the Mesozoic Palaeogene section, the Gaudryina and Gaudryinopsis genera are often established as the index-species of the distinguished foraminiferal zones. This information is schematically demonstrated in the table where the described genera are assigned to the peaks of transgressions. The maximum transgression has been determined in the Middle Eocene (the Middle Lyulinvosrakaya Subsuite), and the Middle Eocene Gaudryinopsis subbotinae Zone has been established from these deposits by the author. The zonal species occurs widely throughout Western Siberia, and the deposits of this zone are supposed to correspond to the Middle Eocene (second) rock complex of the Lomonosov Ridge section (the Arctic Ocean). This is evidenced by the lithology of the rocks, which are composed of the biosiliceous material and are similar to deposits of the Middle Lyulinvosrakaya Subsuite of Western Siberia. They are also supposed to enclose the West-Siberian index species Gaudryinopsis subbotinae Podobina or its vicariant. The assignment of different species of the Gaudryinopsis Genus and other genera of the Ataxophragmiida Order to deposits corresponding to the maximum transgressions enhances their stratigraphic and correlational significance, enabling to adjust the age of the most disputable stratigraphic units.