Budowa geologiczna okolic Wrocławia a trzęsienie ziemi w 1976 r.

Abstract

ON RELATIONS BETWEEN THE RECORDED QUAKES AND GEOLOGICAL STRUCTURE IN THE VICINITIES OF WROCŁAW Summary Four structural stages (Precambrian, Carboniferous, Permo-Triassic and Tertiary and Quaternary) are differentiated in geological structure of the vicinities of Wrocław. Tertiary sediments form here a cover (138.0-260.0 m thick) on older ones (Figs. 1, 2, Table 1). Precambrian strata are represented by biotite and amphibolite schists, erlans, hornfelses, gneisses and granodiorites. North of Wrocław, they are overlain by Lower Carboniferous, conglomeratic at the base and passing upwards into gray graywacke sandstones and dark-gray shales. Rotliegendes, over 100 m thick, rests on crystalline rocks in southern part of the area, and the Carboniferous in the north. It is represented by fine- and medium-grained, locally conglomeratic brownish graywacke sandstones, passing into conglomerates at the base and gray sandstones at the top. Zechstein here comprises gray limestones, beige dolomites, dark-gray and brown-red shales and gray anhydrites of four cyclothems: Werra, Stassfurt, Leine and Aller. The cyclothems are best developed north of Wrocław. The majority of members of all the cyclothems, except for limestone member of the Werra and brown-red shales assigned to the Aller, wedge out towards that town and south of it. (…)