The Lessini Mountains carbonate plateau (Venetian Prealps, It- aly) is one of the most important karst areas in Italy. Along with alpine-type caves and well-developed karst landscapes, palae- okarst features are also common. In most cases, palaeokarst is represented by caves and ssures lled by limonitic-haematitic palaeosols (ochres) in which fossiliferous arenite layers are sometimes embedded. ese features developed and fossilised during a late Eocene-middle Miocene phase of emersion. Be- tween the Palaeocene and the Oligocene, over a time span par- tially overlapping the development of palaeokarst, basaltic vol- canism took place in the Lessini Mountains. Along with ochre lls, cave passages that were intruded by basalt provide further evidence that a well as developed karst network existed in the Lessini Mountains area in the middle-late Palaeogene. More- over, basalt intrusions provide the only available data for the dating of palaeokarst in the central Lessini Mountains, where fossiliferous layers in ochre beds have not been found. We have started a new survey on palaeokarst in the Lessini pla- teau, with the aim of identifying ancient features on the basis of unusual lls (namely, ochre and basalt) and morphologies. New instances of basalt intrusions in three caves, Spigola di Canova, Covoli di Velo, and Covolo della Croce, have been recognised; evidence of pre-existing karst features lled by basalt in a pre- viously studied cave (Grotta A Veja) has been identi ed, and an unusual basalt outcrop that might relate to palaeokarst has also been observed. is paper aims to document the new ndings and to discuss previous ones. At the same time, we would like to point out some cautionary observations to prevent a “basalt = palaeokarst” misunderstanding.

Basalt intrusions in paleokarst caves in the Central Lessini mountains (Venetian Prealps, Italy)

GONZATO, Guido;CHIGNOLA, Roberto
2017

Abstract

The Lessini Mountains carbonate plateau (Venetian Prealps, It- aly) is one of the most important karst areas in Italy. Along with alpine-type caves and well-developed karst landscapes, palae- okarst features are also common. In most cases, palaeokarst is represented by caves and ssures lled by limonitic-haematitic palaeosols (ochres) in which fossiliferous arenite layers are sometimes embedded. ese features developed and fossilised during a late Eocene-middle Miocene phase of emersion. Be- tween the Palaeocene and the Oligocene, over a time span par- tially overlapping the development of palaeokarst, basaltic vol- canism took place in the Lessini Mountains. Along with ochre lls, cave passages that were intruded by basalt provide further evidence that a well as developed karst network existed in the Lessini Mountains area in the middle-late Palaeogene. More- over, basalt intrusions provide the only available data for the dating of palaeokarst in the central Lessini Mountains, where fossiliferous layers in ochre beds have not been found. We have started a new survey on palaeokarst in the Lessini pla- teau, with the aim of identifying ancient features on the basis of unusual lls (namely, ochre and basalt) and morphologies. New instances of basalt intrusions in three caves, Spigola di Canova, Covoli di Velo, and Covolo della Croce, have been recognised; evidence of pre-existing karst features lled by basalt in a pre- viously studied cave (Grotta A Veja) has been identi ed, and an unusual basalt outcrop that might relate to palaeokarst has also been observed. is paper aims to document the new ndings and to discuss previous ones. At the same time, we would like to point out some cautionary observations to prevent a “basalt = palaeokarst” misunderstanding.
paleokarst
basalt intrusions
cave fills
Lessini Mountains
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11562/962783
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