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Record: oai:ARNO:505970

AuthorN. Schulman
TitleGeology of Tornafort area, Central Pyrenees, Noguera de Pallaresa, Prov. de Lerida, Spain
JournalLeidse Geologische Mededelingen
AbstractA small area limited in the north by the Boca del Cantó, in the west by the Pallaresa river and in the south by the crest of the Montaña de Bahent and reaching westwards as far as the village of Feixa was surveyed in detail. Previous work by Prof. de Sitter and some of his pupils had revealed that in the steep southern slope of the Boca del Cantó several recumbent folds occur with Ordovician shales in the anticlinal cores and Devonian in the synclines. The work was carried out on the topographical base of an 1:25.000 enlargement of the official 1:50.000 map, sheets 214, Sort and 215 Seo de Urgel, which proved to be far from satisfactory. Aerial photographs were not available.
The Tornafort area is limited in the north by an important fault, which runs practically in the bed of the Boca del Cantó. Tins fault forms the southern limit of the axial zone of the Pyrenees, north of it we find the Lower Triassic conglomerates, sandstones and shales covering unconformably strongly microfolded non metamorphic Ordovician. Near the mouth of the Boca del Cantó this clastic Trias is covered by the evaporite facies of the Keuper, with ophites and muschelkalk floats. The latter formation forms also the western boundary of our region on the lower slopes of the Tornafort hill towards the Pallaresa river, again separated from the Paleozoic by a north-cast trending fault. Thus the Tornafort area forms the northern border zone of the Nogueras zone as it has been defined by Peter Misch (1934). This Nogueras zone is known to have been strongly deformed by alpine orogeny because a little further south and west we see that the paleozoic has been folded together with the Triassic. A section by de Sitter (1957) crossing the Pallaresa river just west of our region shows a Devonian anticlinal core with Trias in the flanks. Our Tornafort region, however, is separated from the structure given by this section by a thrust along which the Devonian with Silurian at its base has been thrusted on the Triassie. This thrust forms the southwest boundary of our map, and the Tornafort structure does not seem to be connected with the just mentioned anticline, as has been done by de Sitter in his section, where the Tornafort structure is drawn as the core of a second anticline further south.
Document typearticle
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