J. Villalaín

Abstract This work synthesizes the new geoarchaeological and paleontological data collected within the Quaternary deposits of the Prados-Guatén Depression (SW Madrid City). New data are linked to the railworks of the future AVE Madrid-Levante and complementary research of the Quaternary Madrid Working Group (GQM) of AEQUA. Sandy Quaternary deposits within the Depression are assembled in offlapped fluvial terraces at +13-16 and +8m on ancient fluvial sands. These ancient deposits contain Pleistocene fauna (Mammuthus primigenius NESTI y Equus ferus cf. mosbachensis) and acheulian flint industry with bifaces and flakes of Middle Palaeolithic. Paleomagnetic analyses on the recent terraces throw ages older as 126,000 +/- 26.000 years BP for the +13-16 m terrace and of 20,000 - 17,000 years BP for the youngest +8m fluvial terrace. This indicates recent fluvial landscape shaping of the Depression from the Last Interglacial (OIS 5).

ABSTRACT Astract: The purpose of this work is to use paleomagnetism as an instrument to bring out informations to solve geological problems in two Jurassic-Cretaceous basins in the Moroccan High Atlas. The Aït Attab and Ouaouizaght basins are located in the northern edge of the central High Atlas, that forms part of the alpine Atlasic belt. It is an intraplate belt, resulting from inversion of extensional and strike-slip basins. Thermal demagnetization reveals a similar characteristic component in almost all sites in the Ait Attab basin. These results resolve the problem of the primary vs. secondary origin of the curved shape in this syncline. Paleomagnetic sites of Aït Attab basin give a positive fold test, indicating that the remagnetization was recorded when the layers were horizontal. In the Ouaouizaght basin, Middle Jurassic to Aptian units acquired a syn-folding remagnetization, whereas the Albo-Cenomanian red beds show a pre-folding magnetization. Jurásico superior al Aptiense muestran una remagnetización" syn-folding", mientras que las unidades Albo-Cenomanienses muestran una magnetización pre-pliegue.

The paleomagnetic results obtained in 23 sites from red beds of the northern border of the inverted Cameros Basin (northern Iberian Peninsula) prove a Cretaceous widespread remagnetization. Paleomagnetic and rock magnetic analyses indicate that the Natural remanent magnetization (NRM) is dominated by a stable and always normal polarity component carried by haematite. Two conglomerate test and five-fold test indicate that

ABSTRACT a b s t r a c t The aim of this work is to study the Anisotropy of the Magnetic Susceptibility (AMS) in two Jurassic–Cre-taceous synclines located in the northern border of the Central High Atlas (Morocco): the Aït Attab and Ouaouizaght basins. AMS is used in order to obtain the magnetic fabric and its relationship with the kine-matic evolution of both basins. The tectonic evolution of the basins, still under discussion, is mostly con-sidered as the result of inversion during Tertiary and perhaps since Bathonian, of extensional and/or strike-slip Jurassic basins. Both basins are filled with Upper Jurassic to Lower Cretaceous silts and sand-stones, with less frequent marine marly limestones. The bulk magnetic susceptibility (km) generally shows higher values in the red facies (163.2 EÀ6 in AT and 168.6 EÀ6 in WZ) than in the yellowish marly limestones (97.88 EÀ6 in AT and 132 EÀ6 in WZ). Most sites show an oblate magnetic fabric. The rock magnetic analyses indicate that the main carrier of the magnetic susceptibility for the red facies is hematite, whereas in the yellowish facies there is a domi-nance of paramagnetic minerals. In both basins, the magnetic lineation (long axis of the ellipsoid, k max axes) shows a predominant E–W direction. The overlapping of the stress fields during the Atlasic basins evolution, in both compressional and extensional regimes and hinder the straightforward interpretation of the magnetic fabrics. However, a coeval N–S compression during the times of sedimentation with an E– W transtension can explain the magnetic lineation found in many of the sites analyzed in the present work. There are also other less frequent directions of k max axes (NE–SW and NW–SE) are interpreted as the result of local change of the stress field during the early extensional stage of basin formation.

SUMMARY Available apparent polar wander (APW) paths for the 200 Ma configuration of Pangea, just prior to the opening of the Central Atlantic Ocean, differ as much as 10 o in arc length. Here, we add new data from northwest Africa for this time, obtained from the northeast-trending Foum-Zguid and Ighrem dykes (ca. 200 Ma). These dykes form part of the northern domain of the Central Atlantic Magmatic Province (CAMP), and crosscut the Anti-Atlas Ranges in Morocco, and compositionally correspond to quartz-normative tholeiites ...