Zmiany układu spękań w cechsztyńskich skałach węglanowych monokliny przedsudeckiej

Abstract

VARIATIONS OF THE JOINT PATTERNS IN THE ZECHSTEIN CARBONATE ROCKS OF THE FORE-SUDETIC MONOCLINESummaryJoints orientation has been measured in a copper mine of the Fore-Sudetic monocline to define the spatial variation of the joint system in tectonically disturbed and undisturbed zones. The measurements were completed in Zechstein carbonate-dolomitic rocks and concentrated in ten sites within an area of about 3 squ km. In this area tectonic deformations are represented by NW-SE and WNW-ESE faults, their amplitude being 0,5-30 m. Two conjugate joint systems have been found in this area represented by two parts subperpendicular to each other: NNW-SSE and WSW-ENE (the first system) and NNE-SSW and WNW-ESE (the second system). Frequently the WSW-ENE and the WNW-ESE directions interfere with each other and form one maximum on the diagrams (Figs. 2 and 3). In the non-disturbed part of the deposit the NNW-SSE joint group predominates, the whole system being fairly uniform in various parts of the mine. Close to the faults the individual directions are reoriented and the share of various joints changes. In the direct neighbourhood of the faults the predominant joints and mineral veins are those that coincide with the directions of tectonic lines. A zone, several hundreds of metres wide, with the predominance of joints subperpendicular to the fault line (NNE-SSW) is associated with faults of major thrusts (more than several metres) (Fig. 4). In respect to faults the joints are differentiated as to their age. In the area examined faults were formed irrespective of the NNW-SSE joints and are younger than these joints. But the more intensive NNE-SSW jointing in the neighbourhood of major faults is indicative of mutual genetic and age relationships.