This paper takes into account the relationships between "autochthonous" deposits of the Umbro-Marchean-Romagna sequence and allochthonous ones of the Val Marecchia sheet. New structural data, regarding both Epiligurian and Early Pliocene deposits, show strong evidences of the existence of synsedimentary tectonics. Six depositional sequences, separated by erosional surfaces, have been recognized inside Epiligurian deposits and they were controlled by different tectonic phases. During these phases the movement of the Val Marecchia sheet took place by thrust faults set in imbricated slices along one or more surfaces: Apenninic compressional regime (from SW to NE) caused this pattern and modelled "autochthonous" sequence in folds and slices overthrusted to NE.A deep structural depression, transversal to the Apenninic chain, probably related to wrench-fault tectonics (Grosseto-Marecchia line) occurred since Tortonian and controlled the sedimentation of the Umbro-Marchean-Romagna sequence until Early Pliocene (Globorotalia puncticulata Zone).A palaeogeographic reconstruction of this area during Middle Miocene-Early Pliocene is proposed; Apenninic compressional regime played two different roles in the construction of the structural elements of the Val Marecchia area. Structural "autochthonous" highs became evident since Middle-Late Miocene and controlled rate and dynamics of the "substratum" of the Val Marecchia sheet. On the other hand over the allochthonous sheet small sedimentary basins (piggyback and overstep basins) were formed during Middle Miocene to Early Pliocene and their stratigraphic wedging and unconformities were controlled by continuous movement of the Val Marecchia sheet.
|Anno di pubblicazione:||1990|
|Titolo:||Geologia dell'Appennino marchigiano-romagnolo tra le valli del Savio e del Foglia (Note illustrative alla carta geologica a scala 1:50.000).|
|Autori:||S. CONTI; con un contributo di FREGNI P.|
|Appare nelle tipologie:||Articolo su rivista|
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