Lower plate geometry controlling the development of a thrust-top basin: the tectonosedimentary evolution of the Ofanto basin (Southern Apennines)

Emilio Casciello,Marco Snidero,Jaume Vergés,Massimo Cesarano,Paolo Esestime,Gerardo Pappone

doi:10.1144/jgs2011-066

Emilio Casciello, Marco Snidero + Show 4 more

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https://doi.org/10.1144/jgs2011-066

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Abstract

The Ofanto basin is a Pliocene–Pleistocene thrust-top basin that formed with an unusual east–west orientation along the frontal part of the Southern Apennine Allochthon during the latest stages of tectonic transport. Its tectonic and sedimentary evolution was studied integrating field surveys, biostratigraphic analyses and the interpretation of a large seismic grid. Well data and seismic interpretation indicate that a large east–west-trending normal fault underlies the northern margin of the basin, displacing the Apulian carbonates that form the foreland and the footwall of the Southern Apennine Allochthon. In our reconstruction the Ofanto basin formed at the rear of the bulge caused by buttressing of the Southern Apennine Allochthon against this normal fault. In a second stage of contraction, the footwall of the Southern Apennine Allochthon was involved in deformation with a different trend from the normal faulting and buttressing. This caused eastward tilting of the basin and broad folding around its eastern termination. Good stratigraphic constraints permit the age of buttressing to be defined as Early Pliocene, and that of the shortening in the Apulian carbonates as Early Pleistocene. This study highlights the importance of early orogenic normal faults in conditioning the evolution of the frontal parts of orogenic wedges. Supplementary material: A 3D reconstruction of the base of the Pliocene deposits of the Ofanto basin, based on seismic interpretation, is available at www.geolsoc.org.uk/SUP18559 .

Highlights

Geofísica, Facultat de Geologia, Universitat de Barcelona. 08028 Barcelona, Vergés Jaume - Group of Dynamics of the Lithosphere (GDL), Institute of Earth
E-W trending surficial structures, correspond to the orientation of the normal fault in the Apulian carbonates (Fig. 7), which forms a structural step with 1 km throw just below the northern margin of the Ofanto basin
The first stage, lasting throughout the Early Pliocene and possibly extending into the lowermost part of the Late Pliocene, is the main translation of the SAA over the Apulian carbonate platform, which behaved as the inactive footwall, passively influencing the emplacement of the Southern Apennine Allochthonous with its preexisting structures (Fig. 9 A-C)

Summary

Introduction

08028 Barcelona, Vergés Jaume - Group of Dynamics of the Lithosphere (GDL), Institute of Earth. Its tectonic and sedimentary evolution was studied integrating field surveys, biostratigraphic analyses and the interpretation of a large seismic grid. Well data and seismic interpretation indicate that a large E-W trending normal fault underlies the northern margin of the basin, displacing the Apulian carbonates that form the foreland and the footwall of the SAA. In a second stage of contraction, the footwall of the SAA was involved in deformation with a different trend from normal faulting and buttressing. This caused eastward tilting of the basin and broad folding around its eastern termination. This work highlights the importance of early-orogenic normal faults in conditioning the evolution of the frontal parts of orogenic wedges

Discussion

Conclusion