Nowe dane do stratygrafii węglanowego ordowiku Lubelszczyzny
Abstract
Summary
Stratigraphy of Ordovician carbonate rocks in two borehole columns Tarkawica 1 and Wierzbica 1 (Lublin region, SE Poland - Fig. 1) is discussed on the basis of the recorded conodont assemblages and their distribution. The results of the studies are as follows:
1) Glauconite from the base of Ordovician carbonate series represents diff erent members of the Arenigian (Fig. 2). The conodont record shows that it is assignable to the Paroistodus zone (lowermost Latorpian) in the borehole column Tarkawica 1, and the Baltonious navis zone (Lower Volkhovian) in the borehole column Wierzbica 1.
2) A large stratigraphic gap has been found at the Lower-Middle Ordovician boundary. The gap corresponds to lower part of the Pygodus serratus zone (Table 2) or, sometimes, an interval from the Eoplacognathus robustus subzone to Baltoniodus navis zone (see Fig. 2 and Tables 1 and 2). It was certainly due to a break in sedimentation and erosion which reached down to the Lower Arenigian. Unpublished Author's data show that such phenomena are common in the Polish part of the Precambrian Platform.
3) The Amorphognathus tvaerensis zone (or, more, precisely, Baltoniodus gerdae subzone) is the youngest conodont unit differentiated in the studied section. In the Late Caradocian there began sedimentation of strata of clay lithofacies. They yield graptolites indicative of the Diplograptus multidens and Dicranograptus clingani zones as well as some innumerous conodonts of negligible stratigraphic value.
The lack of appropriate core material precludes studies on higher parts of the Ordovician in these borehole columns.
Stratigraphy of Ordovician carbonate rocks in two borehole columns Tarkawica 1 and Wierzbica 1 (Lublin region, SE Poland - Fig. 1) is discussed on the basis of the recorded conodont assemblages and their distribution. The results of the studies are as follows:
1) Glauconite from the base of Ordovician carbonate series represents diff erent members of the Arenigian (Fig. 2). The conodont record shows that it is assignable to the Paroistodus zone (lowermost Latorpian) in the borehole column Tarkawica 1, and the Baltonious navis zone (Lower Volkhovian) in the borehole column Wierzbica 1.
2) A large stratigraphic gap has been found at the Lower-Middle Ordovician boundary. The gap corresponds to lower part of the Pygodus serratus zone (Table 2) or, sometimes, an interval from the Eoplacognathus robustus subzone to Baltoniodus navis zone (see Fig. 2 and Tables 1 and 2). It was certainly due to a break in sedimentation and erosion which reached down to the Lower Arenigian. Unpublished Author's data show that such phenomena are common in the Polish part of the Precambrian Platform.
3) The Amorphognathus tvaerensis zone (or, more, precisely, Baltoniodus gerdae subzone) is the youngest conodont unit differentiated in the studied section. In the Late Caradocian there began sedimentation of strata of clay lithofacies. They yield graptolites indicative of the Diplograptus multidens and Dicranograptus clingani zones as well as some innumerous conodonts of negligible stratigraphic value.
The lack of appropriate core material precludes studies on higher parts of the Ordovician in these borehole columns.