The understanding of the thermal history of mountain chain units is crucial to define the pattern of tectonic loading and the time-space evolution of an orogen where tectonic exhumation processes occurred at shallow crustal levels. In the present study we integrate stratigraphic, structural and morpho-tectonic data with different organic and inorganic parameters which record the thermochronological evolution of rock units exposed within the External Zone of the Apennines. Our data include: (i) vitrinite reflectance, (ii) fluid inclusions, (iii) clay mineralogy (illite crystallinity, expressed as Kübler Index, KI, percentage of illitic layers in illite/smectite (I/S) mixed layers, and abundace of white mica polytypes), and (iv) apatite fission tracks. The southern Apennines are a NE-verging fold-and-thrust belt which formed from Late Oligocene to Pleistocene times. They include remnants of a Cretaceous to Palaeogene accretionary complex (ophiolite-bearing Ligurian units) overlying foreland fold and thrust belt units derived from the deformation of the (Afro) Adriatic continental paleomargin. Allochthonous carbonate platform units and pelagic basin successions derived from the Appenninic Platform and Lagonegro Basin, respectively, and stratigraphically overly Neogene foredeep and wedge-top basin deposits. These allochthonous units are detached from their original substratum and transported onto the foreland succession of the Apulian Platform. These rocks are also partially involved in the thrust belt, forming the so-called 'buried Apulian belt' which underlies the allochthonous units. The detachment between the allochthon and the Apulian units is marked by a mélange zone, as shown by data collected in various wells drilled in the area. From a methodological point of view, our data reveal a quite good fitting among different thermal indicators which provided constraints throughout the thermal evolution of the analysed sequences. From a regional point of view, the following points arise: - general increase of tectonic loading from the internal to the external Tectonic Units with a gap in thermal maturity from the Apenninic Platform (less than 2 km) to the Lagonegro Basin (ranging between about 4 and 5 km) and maximum values in the Apulia Carbonate Platform (more than 5 km); - increasing thermal maturity from the top to the bottom of the Lagonegro successions - variations along-strike of both tectonic loadings and exhumation rates in the Lagonegro Units.
Thermal constraints and modelling for the Neogene-Quaternary evolution of the Lucanian sector of the Southern Apennines (Italy)
ZATTIN, MASSIMILIANO;ZUFFA, GIAN GASPARE
2004
Abstract
The understanding of the thermal history of mountain chain units is crucial to define the pattern of tectonic loading and the time-space evolution of an orogen where tectonic exhumation processes occurred at shallow crustal levels. In the present study we integrate stratigraphic, structural and morpho-tectonic data with different organic and inorganic parameters which record the thermochronological evolution of rock units exposed within the External Zone of the Apennines. Our data include: (i) vitrinite reflectance, (ii) fluid inclusions, (iii) clay mineralogy (illite crystallinity, expressed as Kübler Index, KI, percentage of illitic layers in illite/smectite (I/S) mixed layers, and abundace of white mica polytypes), and (iv) apatite fission tracks. The southern Apennines are a NE-verging fold-and-thrust belt which formed from Late Oligocene to Pleistocene times. They include remnants of a Cretaceous to Palaeogene accretionary complex (ophiolite-bearing Ligurian units) overlying foreland fold and thrust belt units derived from the deformation of the (Afro) Adriatic continental paleomargin. Allochthonous carbonate platform units and pelagic basin successions derived from the Appenninic Platform and Lagonegro Basin, respectively, and stratigraphically overly Neogene foredeep and wedge-top basin deposits. These allochthonous units are detached from their original substratum and transported onto the foreland succession of the Apulian Platform. These rocks are also partially involved in the thrust belt, forming the so-called 'buried Apulian belt' which underlies the allochthonous units. The detachment between the allochthon and the Apulian units is marked by a mélange zone, as shown by data collected in various wells drilled in the area. From a methodological point of view, our data reveal a quite good fitting among different thermal indicators which provided constraints throughout the thermal evolution of the analysed sequences. From a regional point of view, the following points arise: - general increase of tectonic loading from the internal to the external Tectonic Units with a gap in thermal maturity from the Apenninic Platform (less than 2 km) to the Lagonegro Basin (ranging between about 4 and 5 km) and maximum values in the Apulia Carbonate Platform (more than 5 km); - increasing thermal maturity from the top to the bottom of the Lagonegro successions - variations along-strike of both tectonic loadings and exhumation rates in the Lagonegro Units.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
