Pergamon J. Geodynamics Vol. 22. No. 314, pp. 207-227.19% Copyright Q 1996 Elsevier Science Ltd zyxwvuts PII: SO264-3707(%)00010-5 Printed in GreatBritain. All tights reserved 0264-3707/% $15.00+0.00 THE SIGNIFICANCE OF TECTONIC-RELATED TERTIARY REMAGNETIZATION ALONG THE MARGINS OF THE VALENCIA TROUGH J. M. PARIb’ and E. ROCA2 ’ Institut de Cikncies de la Terra, CSIC, Marti i Franquks s/n, 0802%Barcelona, Spain ’ Dept. Geologia Din&mica, Geofisica i Paleontologia, Universitat de Barcelona, 08071 -Barcelona, Spain zyxwvutsr (Received 20 June 1995; accepted in revised form 26 March 1996) Abstract-The paleomagnetic data from the margins of the Valencia Trough are derived from Mesozoic and Tertiary rocks from the Balearic Islands, Catalan Coastal Ranges and Eastern Iberian Chain. These rocks are affected by a complex structural evolution consisting of an initial compressive stage followed by one of extension. Cenozoic paleomagnetic data indicate that rotations occurred during the Paleogene compression and before the extension started (Lower Miocene) in the Catalan Coastal Ranges. In contrast, in the Balearic Islands the rotations are synchronous to both compressional (Late Oligocene-Middle Miocene) and extensional tectonics (post-Middle Miocene). In both areas the Mesozoic limestones are remagnetized. In the Catalan Coastal Ranges they display the same direction as the Paleogene syn-compressive deposits whereas in the Balearic Islands they conform with Lower Miocene (Burdigalian) syn- compressive rocks. It is concluded that the processes of remagnetization that affected eastern Iberia are related to a compressive rather than an extensional tectonics regime. Copyright 0 1996 Elsevier Science Ltd INTRODUCTION Paleomagnetic studies from erogenic belts, or simply deformed areas, commonly show directions of remanent magnetization that group most closely before or after only partial structural correction. To the present, these secondary magnetizations were not used profusely. Nevertheless, the appearance of secondary magnetizations can be considered and used for tectonic reconstruction (Kent and Opdyke, 1985; Elmore and McCabe, 1991 and references therein). The study of tectonic remagnetization is a powerful means for the establishment of deformational processes of erogenic belts. Two types of remagnetization related to tectonics can be distinguished: 1) magnetization that occurred during deformation or very early after it; and 2) magnetization acquired after tectonic activity but still related to the deformational process, i.e. syn- and post-tectonic remagnetizations. Beyond this simple classification, no distinction has been reported so far between the magnetizations associated with compressive regimes and those associated with extensive ones. The Iberian Peninsula is a favorable area to study remagnetizations associated with both compressive and extensional regimes, since its present structure is characterized by the 207