Podział litostratygraficzny dewonu w profilu otworu wiertniczego Kowala 1

Abstract

Najpełniejszy wiertniczy profil węglanowej części dewonu z południa Gór Świętokrzyskich został podzielony na 5 nieformalnych jednostek litostratygraficznych wyższego rzędu i 9 jednostek niższej rangi. Jednostki te zostały tu scharakteryzowane, a ich granice zdefiniowane. Tak zarysowany schemat podziału porównano z podobnym schematem otworu Janczyce I ze wschodniej części Gór Świętokrzyskich, sugerując szeroki regionalny charakter wielu wyróżnionych tam jednostek i możliwość ich formalizacji.

Lithostratigraphic subdivision of the Devonian sequence in the Kowala 1 borehole

The Kowala 1 borehole is located in the southwestern part of the Holy Cross Mts (Fig. 1). The column is 890.3 m thick and aside of clastic rocks at the bottom (2.7 m thick) it represents carbonate part of the Devonian sequence from Eifel up to the Famennian. The Devonian is underlain by the Cambrian sediments at the bottom and it vis overlain by the Carboniferous at the top. 5 nonformal lithostratigraphic of higher rank and 9 of lower rank units have been distinguished in the Kowala 1 borehole. The units are characterized and their boundaries defined. Those are (from bottom to top):

- Clastic rocks; 2.7 m thick.

I. Bioturbated dolomites and dolomites with macrofauna, 95.9 m thick:

- Dolomites with macrofauna, 10,8 m thick.

II. Laminated dolomites and detrital dolomites, 119,1 m thick.

III. Stromatoporoid-coral dolomites and limestones, 160.5 m thick:

- Marly limestones, 15.0 m thick.

IV. Detrital limestones, 304.1 m thick.

V. Marly series. 206.8 m thick:

- Marls, limestones and nodular sediments, 36.9 m thick;

- Marls and laminated limestones, 80.7 m thick;

- Marls with nodules of limestones, 26.2 m thick;

- Marls, limestones and nodular limestones, 28.5 m thick;

- Marls and claystones with limestone intercalations, 24.2 m thick;

Nodular limestones, 10.3 m thick.

It is generally accepted that the Devonian sediments corresponding to units I and II belong to Eifelian, III - to Givetian, IV - to Frasnian and V - to Famennian. This subdivision is hardly documented by fossil finds. The stratigraphic position of the marly series has been described by H. Żakowa and K. Radlicz (1990), M. Nehring-Lefeld (1990) and E. Turnau (1990). A considerable similarity in lithology and thickness has been observed to the column of the Janczyce I borehole localised in the eastern part of the Holy Cross Mts (M. Narkiewicz, I. Olkowicz-Paprocka, 1983, Fig. 3). Basing on the Kowala 1 column the elaboration of the formal regional lithostratigraphic subdivision of Devonian in the southern part of the Holy Cross Mts, the Nida Basin and possibly also in the northeastern border of the Upper Silesian Coal Basin seems to be possible.