New K/Ar data on separated dark mica indicate that the melagabbroic body exposed to the east of the Acquarotta canal (Gargano Northern coast, Pietre Nere point) with an age of 58-59 Ma, is slightly younger than the 62.2 Ma old melasyenitic body outcropping to the west of the canal. New delta-34S data confirm the Upper Triassic age of both the anhydrites of the Foresta Umbra 1 well (east of Pietre Nere point) and the gypsum of the Acquarotta canal. Based on the actual presence of anhydrites in the Foresta Umbra 1 borehole as well as on thermodynamic considerations, it is likely that the Triassic limestones and evaporites of the Pietre Nere point were squeezed and pushed towards the surface by tectonic events and not by diapiric ascent. Apatite fission track analysis indicates for the last tectonic phase a Late Pliocene-Early Pleistocene age. Anhydrites were gypsified afterwards, at very shallow depth.
New geochronological data on igneous rocks and evaporites of the Pietre Nere point (Gargano Peninsula, southern Italy)
Bigazzi G;Laurenzi;M A;Principe C;
1996
Abstract
New K/Ar data on separated dark mica indicate that the melagabbroic body exposed to the east of the Acquarotta canal (Gargano Northern coast, Pietre Nere point) with an age of 58-59 Ma, is slightly younger than the 62.2 Ma old melasyenitic body outcropping to the west of the canal. New delta-34S data confirm the Upper Triassic age of both the anhydrites of the Foresta Umbra 1 well (east of Pietre Nere point) and the gypsum of the Acquarotta canal. Based on the actual presence of anhydrites in the Foresta Umbra 1 borehole as well as on thermodynamic considerations, it is likely that the Triassic limestones and evaporites of the Pietre Nere point were squeezed and pushed towards the surface by tectonic events and not by diapiric ascent. Apatite fission track analysis indicates for the last tectonic phase a Late Pliocene-Early Pleistocene age. Anhydrites were gypsified afterwards, at very shallow depth.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.


