Występowanie megaspor w obrębie zaburzonych warstw i liasu w profilu Koszalina

Abstract

OCCURRENCE OF MEGASPORES IN DISTURBED RHAETIC AND LIASSIC STRATA OF THE KOSZALIN PROFILESummaryMegaspore examinations made on the Koszalin profile have contributed not only to the determination of stratigraphical position of the strata in study, but they have also corroborated the existence of tectonic disturbances observed by R. Dadlez within the Rhaetic and Liassic formations. These disturbances, responsible for the recurrence of the Upper and Lower Rhaetic beds and of some Middle and Upper Liassic members, are corroborated by a similar recurrence of the following megaspore assemblages: Trileites pinguis, Horstisporites planatus, and Thomsonia phllica (Tab. 1).Megaspores Trileites pinguis (H a r r i s) Pot., and Verrutriletes utilis (M a r c.) M a r c., appear in the area of Koszalin at a depth of 1478,2 m suggesting their Rhaetic age. The deposits, found to occur above the tectonically disturbed complex, reveal the presence of the following megaspores: T. pinguis (H a r r i s) Pot., V. utilis (M a r c.) M a r c., Bacutriletes tylotus (H a r r i s) Pot., Mimerisporites ales (H a r r i s) Pot., Tasmanitriletes pedinacron (H a r r i s) J u x et K e m p f, and Maexisporites misellus M a r c. These megaspores are a base to distinguish, at a depth of 1389,0–1323,4 m, an Upper Rhaetic T. pinguis assemblage known in Poland from the Wielichowo Beds.At a depth of 1249,0–1149,2 m we observe the occurrence of Nathorstisporites hopliticus J u n g., which allows us to suppose that these deposits are of Hettangian and of Lower Sinemurian age.Above the barren portions of the section, in a series of deposits almost 300 m thick, Horstisporites planatus (M a r c.) M a r c. has been encountered at a depth of 855,8 m, characteristic of the upper members of Liassic formations (Upper Sinemurian-Domerian).At a depth from 844,0 to 817,0 m there occurs an assemblage of Thomsonia phyllica, which is characteristic mainly of the Toarcian deposits. It is represented by the following species: Minerisporites richardsoni (M u r r a y) Pot., Thomsonia phyllica (M u r r a y) Pot., Echitriletes hispidus M a r c., Erlansonisporites sparassis (M u r r a y) Pot., E. excavatus M a r c., Bacutriletes clavatus M a r c., Biharisporites scaber M a r c. and ?Triletes murray (H a r r i s) M a r c.At a depth of 699,6–644,2 m, above the assemblage discussed before and above the series disturbed tectonically, there appear megaspores H. planatus (M a r c.) M a r c., and B. spicatus (M a r c.) M a r c., known from the middle members of the Liassic series. At the top portion of the section (580,0 m) there are found, among others, such megaspores as Trileites murray (H a r r i s) M a r c. and T. phyllica (M u r r a y) Pot., which prove the presence of the uppermost members of Liassic: series, or of those of the lowermost Middle Jurassic.