W sprawie interpretacji profilu starszego paleozoiku w otworze Toruń 1

Ryszard Dadlez

Abstrakt


ON INTERPRETATION OF LOWER PALEOZOIC SEQUENCE FROM THE BOREHOLE COLUMN TORUŃ 1

Summary
Lower Palaeozoic sequence in the Toruń 1 borehole has recently been interpreted in terms of mid-Silurian folding phase (2, 6, 7, 10, 12). Post-Llandoverian or post-Wenlockian folds are thought to be overlain by uppermost Silurian platform cover (Podlasie stage).
An alternative view is here presented. It is based upon a correlation with similar sequences of folded Lower Palaeozoic strata which are known from the Koszalin - Chojnice tectonic zone between the Baltic coast and the Toruń 1 borehole. Nearly twenty borehole columns exist there, each of them characterized by the variable dips in the Ordovician and Silurian beds, up to the Podlasie stage inclusively (4, 11).
It is concluded that a single, post-Silurian tectonic event may account for the folding of the whole succession. Several overturned or recumbent folds, with inverted limbs tectonically reduced or squeezed out, are shown in the sequence (Fig. 1). Faults are interpreted after the geophysical logs (Fig. 2). Another version cannot be excluded, where the later (syn-Variscan) fault cuts the normal limb of an earlier, Caledonian fold (Fig. 3).
Since in the previously mentioned interpretations the term „ Taconic movements" has repeatedly been used as relevant to the discussed movements (6, 7, 10), the meaning of this term is also considered. Two statements are crucial in this respect: (a) - Taconian movements were characteristic of the territories of New England and eastern Canada and were not mid-Silurian (1, 5, 8), and (b) - major deformations in the non-metamorphic British Caledonides were not Taconian because they took place close to the end of the Silurian or in the early Devonian (9).

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