Improving palaeogeographic concepts through structural modelling: balanced cross-sections from the eastern part of the Betic Cordillera (Province of Murcia, Spain)
Abstract
The structural evolution of the External Zone of the Betic Cordillera has been discussed controversially for several decades. In recent years two principal models have been proposed: (1) wrench tectonic style of deformation and (2) thin skinned foreland folding and thrusting. In this contribution we focus on the deformation style in the eastern part of External Zones using balanced cross-sections to quantify deformation and to compare our results with different palaeogeographic reconstructions. Three balanced cross-sections constrain a thin-skinned fold-and-thrust-belt style of deformation with a clear ramp flat geometry of single faults reflecting a transport direction top to the NW. External Subbetic units are thrust upon South Prebetic units. The total amount of shortening exceeds 50% in all three NW-SE oriented sections though shortening is slightly higher in the eastern section and decreases towards the West. This corresponds with an increase in width of the Subbetic unit. Strike-slip faulting and related out-of-section movement reduces the accuracy of the quantification of deformation by plus/minus 10%. Based on the geometry of strike-slip faults we conclude that oblique convergence is accommodated by out-of-section movement towards the WSW. The fact that External Subbetic carbonates with a clear plateau signature are directly thrust upon southern Prebetic units proves inconsistencies in the currently accepted palaeogeographical concepts. We adapted the existing palaeogeographical models according to these structural boundary conditions.
- Publication:
-
EGS - AGU - EUG Joint Assembly
- Pub Date:
- April 2003
- Bibcode:
- 2003EAEJA....12670P