Wstępna charakterystyka petrograficzna skały ultrafemicznej z okolicy Imbramowic

Abstract

PRELIMINARY PETROGRAPHICAL CHARACTERISTICS OF AN ULTRAFEMIC ROCK FROM THE VICINITY OF IMBRAMOWICE Summary In the north-east metamorphic mantle of the Variscian granite massif bearing the name Strzegom-Sobótka massif, there occurs an ultramafic rock erroneously determined on the German geological map (1:25 000) by L. v. z. Mühien as amphibolite. The rock occurs on a small hill, however, a strong mantle consisting of loose Quaternary formations does not allow to determine, more in detail, neither its form of occurrence, nor its relation to the remaining rocks, i.e. to the amphibolites and quartz-mica schists. Preliminary petrographical examinations allowed to distinguish here some relicts of olivines, tremolites, chlorites, serpentinite minerals, chrome-spinels and magnetite. A part of tremolite is developed on the fissuring surface in the form of asbestos. The tremolite represents here a mineral probably originated from primary pyroxenes and partly from olivine. Serpentine minerals mainly came down from olivine. Chlorite is here the latest formed mineral. On the basis of micrometrical analysis the rock bas been determined as serpentinite-tremolite-chlorite one. Peridotite may have been here the primary rock, similarly as it is in the adjacent region of Sobótka, and some changes, particularly chloritization, may have been connected with the post-magmatic activity of the neighbouring granite.