Sedimentary and tectonic burial evolution of the Northern Apennines in the Modena-Bologna area: constraints from combined stratigraphic, structural, organic matter and clay mineral data of Neogene thrust-top basins

Vitrinite reflectance and mineralogical data from 55 samples collected from the Mt. Cervarola Sandstones and the Granaglione Sandstones (thrust-top basin Cervarola Successions) testify the severe thermal maturity of the present-day outcropping successions. This is due to the deep tectonic burial the successions underwent during Miocene chain building. Lower levels of thermal maturity are recorded in the Mt. Cervarola Sandstones. They form a thick upper thrust sheet (Ro% ranging between 1.0 and 1.2%; I% in I/S mixed layers ranging between 80 and 85%). Higher levels of thermal maturity characterise the structurally lower thrust sheets, made up mainly of Granaglione Sandstones (Ro% ranging between 1.2 and 1.5%; and I% in I/S mixed layers between 85 and 90%). Maturity generally decreases from hinterland to foreland. Integration of Ro% and I% in I/S data with published low-temperature indicators allowed to reconstruct a maximum tectonic burial ranging between ∼3.5 on the upper thrust sheet and ∼5 km on the lower ones. Burial was mainly due to the early emplacement of the Ligurian Unit and the Modino Unit on top of the studied units and to later piggy-back thrusting of the Mt. Cervarola Sandstones onto the Granaglione Sandstones. © 2004 Lavoisier SAS. All rights reserved.