Interklasty łupkowe i litoklasty węglanowe w łupkach miedzionośnych monokliny przedsudeckiej

Abstract

Łupki miedzionośne z monokliny przedsudeckiej lokalnie zawierają, interklasty łupkowe i litoklasty węglanowe. Powstanie tych form wiązać należy z istnieniem procesów degradacyjnych panujących w sieciach kanałów pływowych rozprzestrzenionych w depresyjnych częściach monokliny. Procesy te doprowadziły do wyerodowania z podłoża łupków miedzionośnych utworu węglanowego (dolomit graniczny) oraz zintensyfikowały erozję juz skonsolidowanego osadu ilasto-wapnistego, z odznakami pierwotnej mineralizacji i osadzania ich w nowopowstającym łupku miedzionośnym. Litoklasty najczęściej są zlokalizowane w spągowych partiach warstwy łupków, natomiast interklasty występują zazwyczaj wyżej i zajmują środkową i stropową część pionowego profilu tych utworów.

SCHISTY INTERCLASTS AND CARBONATE LITHOCLASTS IN COPPER--BEARING SCHISTS OF THE FORE-SUDETIC MONOCLINE

Discoidal schisty boulders and rarely carbonate boulders are found in the copper-bearing schists in the Fore-Sudetic Monocline. Lithoclasts - mainly decolorized - and light grey karsty dolomites eroded from the copper-bearing schisty basement rocks (border dolomites) and affected by abrasion process through dragging on the bottom by variable strong and channelled tidy currents. They cover the floor of the copper-bearing schists sometims directly on the roof of Weissliegendes (Fig. 1). In section parallel to the sides of work dimensions of the carbonate lithoclasts at the average are 0.07 m in thickness and about 0.45 m in length.

Above the Iithoclasts, in the middle and at the top of the copper-bearing schist profile there arc schisty interclasts showing normal gradation with well separation. Interclasts dimensions range from 0.12 x 0.7 m in the middle to 0.02 x 0.10 m at the top (Fig. 1). They are either disk-shaped or ellipsoidal (Tabls I, II) in the longitudal sections either ball-shaped or ellipsoidal (Tabl. Ill, Fig. 8) in the cross sections. Dip angle of the original bedding planes in adjacent schisty interclasts varies in one another. Discordant clayay - limy lamination in the interclast in relation to the dip of laminae in surrounded schists is observed (Fig. 2). The interclasts are usually composed of clayay limy schists and encircled with thin white calcitic envelope, forming the distinct border between the clast and surroundings (Tabl. II, Fig. 7). Besides it is noticed that CO₂ contents is twice as much in surrounded schists as in the interclast itself. The same relation is also observed in Cu-mineralization that is however several times higher.

Distribution of interclasts and lithoclasts is not uniform in the whole area. They are usually concentrated in the central parts of depression. between elevations of the sandstone roofs - tidy channels perpendicular to depression are filled with copper-bearing schists. Clayay-sandy schist (Tabl. IV, Fig. 10) and clayay-dolomitic schists interlaid with the several centimeter beds of light-grey sandstone (Tabl. IV, Fig. 11). Terrigenic material composing these schists originated, most likely from erosion of the sandstone elevation zones during deepening of forming the narrow passes.