The northern portions of the Catinaccio and Sciliar Buildups provide the best available record of the syn-volcanic evolution of the Dolomites platforms. During the middle Ladinian tectono-magmatic event, the gravitational instability of the slopes cut large scalloped structures into the margins, while huge carbonate fragments ruined into the adjacent basins, generating megabreccia bodies. Although the climax of the volcanic activity deeply affected the carbonate factory in the western Dolomites, it never completely stopped the carbonate production. The resilience of the carbonate systems was indeed such that some calcareous production stayed alive throughout the entire volcanic activity. Even if the study area was close to the major magmatic centres of the Dolomites, a real syn-volcanic carbonate production has been documented. The onset of the volcanism however triggered strong modification in the carbonate facies composition: the margin-slope facies dominated by large syn-depositional cement crusts suddenly gave way to automicritic facies, quite similar to the Cipit Boulders post-volcanic ones. Loose bioclastic resediments also reappeared, after being extremely scanty in the pre-volcanic basins. A fully active carbonate platform growth was promptly re-established at the fading of the magmatic activity. The depositional architecture of the platform finely records a sharp reduction in the subsidence rate just before the magmatic event, a decrease probably related to the crustal heating, within a prevailingly extensional tectonic framework. A comparatively reduced subsidence is also recorded by the moderate thickness (75-80 m) of the post-volcanic platform top beds on the Schlern Plateau. This subsidence evolution reflects the crustal evolution during the Ladinian tectono-magmatic event, which left an important structural heritage that was going to influence the Alpine deformation, more than 100 million years later.
Synvolcanic carbonate production at Middle Triassic scalloped platform margin: examples from the Catinaccio Buildups (Dolomites, Italy)
STEFANI, Marco;CAPUTO, Riccardo
2003
Abstract
The northern portions of the Catinaccio and Sciliar Buildups provide the best available record of the syn-volcanic evolution of the Dolomites platforms. During the middle Ladinian tectono-magmatic event, the gravitational instability of the slopes cut large scalloped structures into the margins, while huge carbonate fragments ruined into the adjacent basins, generating megabreccia bodies. Although the climax of the volcanic activity deeply affected the carbonate factory in the western Dolomites, it never completely stopped the carbonate production. The resilience of the carbonate systems was indeed such that some calcareous production stayed alive throughout the entire volcanic activity. Even if the study area was close to the major magmatic centres of the Dolomites, a real syn-volcanic carbonate production has been documented. The onset of the volcanism however triggered strong modification in the carbonate facies composition: the margin-slope facies dominated by large syn-depositional cement crusts suddenly gave way to automicritic facies, quite similar to the Cipit Boulders post-volcanic ones. Loose bioclastic resediments also reappeared, after being extremely scanty in the pre-volcanic basins. A fully active carbonate platform growth was promptly re-established at the fading of the magmatic activity. The depositional architecture of the platform finely records a sharp reduction in the subsidence rate just before the magmatic event, a decrease probably related to the crustal heating, within a prevailingly extensional tectonic framework. A comparatively reduced subsidence is also recorded by the moderate thickness (75-80 m) of the post-volcanic platform top beds on the Schlern Plateau. This subsidence evolution reflects the crustal evolution during the Ladinian tectono-magmatic event, which left an important structural heritage that was going to influence the Alpine deformation, more than 100 million years later.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
