ALCARAZ PELEGRINA , José Manuel

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The Chafarinas Islands are a group of volcanic outcrops off the north coast of the African continent. Quaternary deposits and calcrete formations cover most of the islands' planed surface, mainly on Rey Francisco I Island. Uranium-series ages are presented for a geological section with 18 m of detrital deposits and calcrete layers. Calcretes...

A study ofthe concentration ofthe U isotopes, 226Ra and 230Th in a groundwater system has been carried out. This aquifer, located in the provinces of Sevilla and Huelva, is the most important in the south of Spain having a surface area of2500 km2 . The proximity of a fertilizer factory complex to this aquifer system is of particular concern...

Experiments were designed to evaluate the behaviour of detritus during the leaching of impure carbonates by applying the U-Th isochron technique. We used one natural detritus and a pure, well-dated CaCO3 , alone and in artificial mixtures. One set of experiments was designed to study the effects of sample pre-treatment on the detritus and a...

U-Series dating method is applied to speleo thems from Los Covachos Cave in the south of Spain. A combination of solvent extraction method with ion exchange resins is used for uranium and thorium isotopes. Uranium concentrations are low and for younger samples correction by detrital contamination is necessary. Ages obtained range from 30 to 135...

The uranium-series method is applied to date relic flowstone from karstic mountains in the south of Spain. Geomorphological mapping shows three staircased erosion surfaces with a typical karst landform. Exhumed flowstones fill the surficial palaeosinkholes and open fractures. Some of the samples analysed were impure carbonates consequently the...

In environmental age dating the 230Th/232Th activity ratio is widely used as an indicator of detrital contamination. A clear relationship between this activity ratio and the carbonate sample's age has previously been demonstrated, whereby a detrital correction must be applied when the 230Th/232Th activity ratio of the leach drops to 20. We...

The geomorphological observations made until now reveal a long morphogenic history for the karst of the Eridrinal: mountains; going back to pre-Quaternary times. The erosion surfaces mapped (Sl, S2 and 53) have å biostatic genesis and are linked to humid media with forest cover, favouring carbonation below a karst- cover. The rëlatiônship...

La Sima of Constantina, located at the northermost part of Seville province, is a karstic cave with a thick terrigenous and chemical (f/owstone) record. These sedimentary formations are representative of the Late Quaternary palaeoenvironmental history about these mountains (Sierra Morena) of the Southwestern lberian Peninsula. There are many...

The geological and geomorphological studies in Los Covachos cave reveal a wide collection of speleothems and a thick archaeological stratigraphies. Both isotopie dating of speleothems C^ThP^U) and charcoal layers C4C), in chemical and terrigenous sediments, show a Quaternary sequence of palaeoenvironmental evolution related with an alternating...