Synsedimentary tensional features in Upper Triassic shallow-water platformcarbonates of the Carnian Prealps (northern Italy) and their importance aspalaeostress indicators

The extensive shallow-water carbonate platform deposits of the Dolomia Prin cipale Formation (Southern Alps, northern Italy) accumulated during the Lat e Triassic, a time of plate-scale reorganization and rifting. Synsedimentar y tensional features such as fractures, neptunian dykes, normal faults, sha tter breccias and laterally discordant intraformational breccias have been studied within a well-preserved platform-to-basin transition in the Monte P ramaggiore area (Carnian Prealps). These tensional features follow three pr eferential orientations: N-S, E-W and NE-SW. To fully explain these differe nt arrays it is proposed that the study area experienced during the Late Tr iassic the waning rifting phase connected to the westward propagation of th e NeoTethys (N-S extension) and the onset of the rifting phase that led in the Middle Jurassic to the opening of the Central Atlantic (E-W extension), with a contemporaneous reactivation of Early-Middle Triassic NE-SW-orienta ted faults. This palaeostress analysis reveals the good potential of tensio nal features as reliable palaeostress indicators.