_Toc174709370">Kuressaare Stage

by H. Nestor

Original text from: Raukas, A., Teedumäe, A. (eds). 1997. Geology and Mineral Resources of Estonia. Estonian Academy Publishers, Tallinn. 436 pp. ISBN 9985-50-185-3. Available online at: sarv.gi.ee/geology.

The Kuressaare Stage was separated from the Kaugatuma Stage by Klaamann (Klaamann 1970a). Later on, the Tahula beds were added to the stage from among the Paadla Stage (Aaloe et al. 1976). The stratotype section is the Kuressaare-GI (Kingissepa) drill core in the interval of 1.5 to 19.8 m (Aaloe et al. 1976). The Kuressaare Stage spreads in the southernmost Saaremaa, on Ruhnu and Kihnu islands and in the southwestern part of the Tõstamaa Peninsula. The outcrop forms a 2-to-10km-wide belt along the southern coast of Saaremaa Island (Fig. 73). The rocks of the stage crop out in temporary excavations and ditches in the Town of Kuressaare and its surroundings. The full thickness of the stage varies from 5.4 m in the Ruhnu to 27.4 m in the Ohesaare borehole (Tab. 9).

The Kuressaare Stage consists of different marlstones (below) and nodular argillaceous biomicritic limestones (above), both containing interlayers of skeletal, lithoclastic and coquinoid grain-, float- and rudstones. The base of the stage coincides with a sharp increase in the clay component and appearance of the elements of a new microfossil assemblage: Pterochitina perivelata, Ozarkodina remscheidensis aff. scanica, Calcibeirichia altonodosa, Thelodus sculptilis.

The Kuressaare Stage contains a rich assemblage of shelly fossils, especially ostracodes.The brachiopod Atrypoidea prunum is extremely numerous and forms coquina banks in the upper, Kudjape beds of the stage. The most typical species are as follows (abbreviations: T - Tahula beds, K - Kudjape beds): Pterochitina perivelata (Eisenack) (T, K), Conochitina granosa Laufeld (T, K), “Parallelopora” ornata Mori (K), “Paleofavosites” moribundus Sokolov (K), Entelophyllum articulatum (Wahlenberg) (K), Tryplasma loveni (M.Edw. et Haime) (K), Atrypoidea prunum (Dalman) (T, K), Calcaribeirichia altonodosa Sarv (T, K), Plicibeirichia numerosa Sarv (K), Retisaculus sulcatus Gailite (K), Limbinariella malornata Sarv (K), Calymene flabellata Männil (K), Pulcherproetus kuressaarensis (Männil) (K), Ozarkodina remscheidensis aff. scanica (Jeppsson) (T, K), O. snajdri parasnajdri Viira et Aldridge (T, K), Thelodus sculptilis Gross (T, K). The Kuressaare Stage has been indirectly correlated with the upper part of the Ludlow Series.

In Estonia, the Kuressaare Stage is represented by the Kuressaare Formation which is subdivided into Tahula beds (below) and Kudjape beds (above) (Aaloe et al. 1976). The Tahula beds mainly consist of argillaceous or dolomitic marlstones with bands of various bio- and lithoclastic limestones. The content of the calcareous component increases northeastwards.

The Kudjape beds are represented by nodular argillaceous biomicritic limestones containing coquinoid interlayers with Atrypoidea prunum and numerous colonial rugose corals.

Plicibeyrichia calcarispinosa Sarv, 1968