Trzeciorzęd i jego węglonośność między Rawiczem i Chobienią

Abstract

TERTIARY AND COAL OCCURRENCE BETWEEN RAWICZ AND CHOBIENIA (POZNAŃ DISTRICT)SummaryThe area in study stretches within the Fore-Sudetic monocline, from Rawicz to Chobienia. Here, the Tertiary basement consists of Mesozoic deposits. The structure of the basement is characterized by an elongated depression, called Rawicz graben. The thickness of the Tertiary deposits in this graben amounts to about 260 m, whereas outside this area it is as much as 280 m on an average. The deposits are Oligocene, Miocene and Pliocene in age. The Tertiary deposits consist of various lithostratigraphical complexes, which have been correlated with the lithostratigraphical unite of the Lusatia region, and of the north-western parts of the Lower Silesia area. Marine or brackish Lower Mosina Beds, Czempin Beds, Upper Mosina Beds and Leszno Beds are referred to the Lower and Middle Oligocene and to the lower part of the Upper Oligocene.To the upper part of the Upper Oligocene are referred Dąbrowa Beds, within the brown coals of the IV group of the seams. The Rawicz Beds with the coal lenses of the III group of the seams belong to the Lower Miocene. The overlying Ścinawa Beds with the II group of the seams, and the Pawłowice Beds, with an II A group of the seams, make here the Middle Miocene member. Both the Adamów Beds and the Middle-Polish Beds with the I group of the seams were laid down at the Upper Miocene time. At the bottom of the Adamów Beds an erosional discordance occurs, most probably related to the movements of the Styrian phase. The overlying Poznań Beds consist of greenish clays and silts referred to the Upper Miocene and Pliocene.The brown coals, found to occur in the area considered, are of autochthonous origin. All the coal seams are characterized by the predominance of earthy lithotype. The coals are good power source, partly being suitable for briquetting and low-temperature carbonizing. The average thickness of the Tertiary coal-bearing series found near Rawicz amounts to 160–210 m. The absolute coal-bearing ratio amounts to 7,5%, and the relative coal-bearing ratio – 4,4%. The highest coal-bearing ratio is observed to occur in the Dąbrowa Beds, Ścinawa Beds and Middle-Polish Beds. Both the Rawicz Beds and the Adamów Beds or almost coal-less.