Analiza porównawcza minerałów ciężkich z drobnoziarnistych utworów czwartorzędowych górnokredowych Wyżyny Lubelskiej

Abstract

COMPARATIVE ANALYSIS OF HEAVY MINERALS FROM QUATERNARY AND UPPER CRETACEOUS FORMATIONS OF THE LUBLIN UPLAND AREASummary311 samploes of Cretaceous and Quaternary deposits have been collected within the area of the Lublin Upland and its neighborhood . Analyses have been made of thin silt cover that rest on limestones, of Eopleistocene, Mesopleistocene and Neopleistocene loesses and silts, as well as of boulder clays, and Cretaoeous and Dano-Paleocene limestones.Both quantitative and qualitative examinations of heavy minerals were base to determine the relations between the silt formations of Quaternary age and rocks of Cretaceous and Dano-Paleocene substratum on the one hand, and the formations of glacial origin, on the other. The results of these examinations are presented in Tab. I, and Figs. 1–8.The composition of heavy minerals forces to draw the following conclusions:­– The rocks in study reveal the following heavy minerals: zircon, garnet, rutile, tourmaline, amphibole and biotite;– Among the transparent heavy minerals that occur in carbonate rocks of the substratum prevail: zircon, rutile and tourmaline; most frequently, garnet is here a supplementary constituent, and the remaining heavy minerals make about 10 per cent (Tab. 1);– In boulder clays  of the Lublin Upland and of its southern and northern forelands, garnets and amphiboles are the main constituents of heavy fraction. On an average, they make about 50 per cent of the transparent heavy minerals there. Biotite is found to occur in several per cent, as well. Minerals resistant to weathering process make about 30 per cent; among them zircon is represented in the first place;– Silt formations are characterized by distinct intermediate features that, on the one hand, are related to  both Cretaceous and Dano-Paleocene formations (this being expressed in the form of a low concentration of heavy minerals, small diameters of the individual components, and predomination of minerals resistant to weathering process.), on the other hand, to the glacial deposits (this being observed in an increased concentration of heavy fraction, in the lager diameters of mineral grains and the presence of constituents not resistant to mechanical and chemical destruction);– The situation of the silt formations is; in relation to the outcrops of source rocks, of great importance, especially for differentiation of mineral composition. Thus, salt formations of similar age can markedly differ in having various percentage of the individual components, and may be related either to carbonate rocks, or to boulder clays .This phenomenon distinctly be seen in the case of limnic-glacial silts. The association of heavy minerals that occurs in the formations within the middle and western parts of the Lublin Upland in the neighborhood of the outcrops of calcareous rocks, resembles that observed in the Cretaceous deposits. In the vicinity of Chełm and Biłgoraj, however, the composition of heavy minerals in the limnic-glacial silts is similar to that of the deposits which occur near  the glacial formations.The composition of heavy minerals in loesses shows that the Pleistocene silts have been here source material for these deposits.