Miocene to Present evolution of the Calabria Tyrrhenian continental margin (Southern Tyrrhenian Sea)

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Abstract

The Miocene to Present evolution of the Calabria Tyrrhenian Continental Margin (CTCM, Southern TyrrhenianSea) are reconstructed using two ENE-WSW oriented, near-vertical seismic profiles (CROP-M27 and SISTER 11lines). The interpreted profiles were time-to-depth converted, merged and translated in a geological section, whichwas also extended to the Tyrrhenian bathial plain and the Calabrian arc using wide-angle seismic data [Scarasciaet al., 1994], and tested with gravity modelling.Across the CTCM, top of KCU is laterally variable in depth forming basins filled by Oligo-Miocene clastic toterrigenous deposits up to 1500m thick. Basins are separated by major structures with contractional or transcurrentkinematics, where faults are arranged in a positive flower structure fashion, affecting the KCU as well as lowerOligocene to Miocene deposits. The Messinian evaporites display essentially a constant thickness of ˜-400m withthe exception of the Paola Basin where deep-water Messinian evaporites are up to 1000 m thick. Plio-Quaternarydeposits display a remarkable variation in thickness from ˜-4.5 km in the Paola Basin to less then 400m in thecentral sector of the margin. Plio-Quaternary sediments are internally sub-divisible into four sub-units separatedby tectonics enhanced angular unconformities.W-ward vergent reverse faults with limited vertical displacement offset the top of KCU as well as the Oligo-Miocene sedimentary and evaporitic units in the eastern side of the Paola basin and in the distal part of the CTCMwhere a number of closely spaced, W-vergent thrust faults are also observed in the Plio-Pleistocene deposits.Along the CTCM, the only significant normal fault which was identified is located around its central sector, dipsto the W and has a displacement of ˜-580m.Across the margin, the Moho was inferred at ˜-35 km beneath the Calabria Arc and shallows up to 24 km in correspondencewith the coastline. Moho deepens again to a depth of ˜-28 km in correspondence with the depocenter ofthe Paola Basin and then climbs gently and regularly reaching a depth of ˜-15 km at the continent-ocean transition.Westward, the ˜-8-9 km thick oceanic crust of the Marsili basin is recognised. The CTCM crust has undergonesubstantial thinning that starts becoming important in correspondence with theWcoast of Calabria where thinningis up to delta=1.5 and, on the whole, shows then a fairly gradual increase from the E to the W where thinningreaches up to delta=3.2 at the continent-ocean transition. The disaggregated analysis of thinning factors for theupper (including KCU, Oligo-Miocene and Plio-Pleistocene deposits) and lower crust identify a long wavelengthtrend which is essentially similar to that of the entire crust thereby suggesting that regional thinning affected inequal amounts the upper and lower crust. Two important deviations are observed, underneath the Paola Basin andtowards the zone of the continent-ocean transition where upper crustal thinning is much larger than the crustalone. On the basis of tectonic features recognised in the KCU, the CTCM may be partitioned into three segmentscharacterized by different post Late-Messinian tectonic deformation and separated by localised strike-slip faultzone.
Original languageEnglish
Pages1-1
Number of pages1
Publication statusPublished - 2009

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