Flexure of lithosphere beneath Apennine and Carpathian foredeep basins: Evidence for an insufficient topographic load
The Pliocene foredeep basin external to the Apennine thrust belt and the late Miocene foredeep basin external to the outer East Carpathians are considered typical molassic foredeeps that formed contemporaneously with thrusting in the adjacent mountain belts. A simple mechanical model in which the response of the lithosphere to loading was approximated by a semi-infinite (broken) elastic plate overlying a weak fluid was used to analyze the deflection of the foreland lithosphere beneath the Apennine and outer East Carpathian foredeep basins along three transects perpendicular to the thrust belts. Comparison between the calculated and observed depth to basement suggests that the (Emplacement of thrust sheets onto the foreland lithosphere during mountain building failed to produce a sufficient load to create the observed foredeep basins and observed topography,) regardless of the position of the slab end or the flexural rigidity assumed for the foreland lithosphere. The authors infer that an additional subsurface load must be present and that its magnitude must be roughly equal to the load created by that part of the thrust belt that is above sea level. For the two Apennine transects, an acceptable fit to the shape and size of the observed foredeep basin was generated by assuming effective elastic plate thicknesses of 8 and 15 km (4.9 and 9.3 mi) and applied vertical forces of 2 x 10/sup 15/ dynes/cm and 1.3 x 10/sup 15/ dynes/cm at the slab end. For the Carpathian transect, an effective plate thickness of 30 km (18.6 mi) and an applied force of 1.5 x 10/sup 15/ dynes/cm generated an acceptable fit. (This study suggests a method whereby an estimate of the depth to autochthonous basement rocks beneath overthrust belts can be made in some areas where this information is not available from seismic or drilling data.)
- Research Organization:
- Harvard Univ., Dept. of Geological Sciences, Cambridge, MA
- OSTI ID:
- 6230769
- Journal Information:
- Am. Assoc. Pet. Geol., Bull.; (United States), Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Vol. 68:6; ISSN AAPGB
- Country of Publication:
- United States
- Language:
- English
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CENOZOIC ERA
DEVELOPING COUNTRIES
EASTERN EUROPE
EUROPE
GEOLOGIC AGES
GEOLOGIC MODELS
GEOLOGIC STRUCTURES
ITALY
LITHOLOGY
MOUNTAINS
POLAND
ROMANIA
SEDIMENTARY BASINS
TECTONICS
TERTIARY PERIOD
TOPOGRAPHY
WESTERN EUROPE