Navarrete, J.(*);. Gutiérrez Maroto, A.(**); Fraile Ramos, C.(*) & Jiménez Ballesta, R.(**) (1997): Evolución de los contenidos en elementos traza en los suelos del entorno del río Monegrillo (Embid de Ariza Zaragoza). Stvd. Geol. Salmant., 33 (1): p. 3-16, 6 figs., 3 tablas. Salamanca.
Key words: Heavy metals, mining area, soils, Iberian system.
[Evolution of trace element contents in soils of the Río Monegrillo environment (Embid de Ariza, Zaragoza, Spain).].
ABSTRACT: The existence of numerous potential foci of pollution by dumpings from abandoned mines is of important environmental concern. This is the case of the River Monegrillo mineralizations (Embid de Ariza, Zaragoza, Spain. To investigate the possible impact of such pollution, 10 samples of surface horizons of soils and alluvions have been analyzed. The elements determined were Cu, Pb an Zn, all of them presents in the mineralizations. For Cu, background values of 12 18.3 ppm were obtained while for Pb and Zn these values were 21.4 34 ppm and 11.5 17.8 ppm. respectively. This prompted the evaluation of variables such as the alluvional character of the soil with constant washing; low organic matter content; basic neutral pH; carbonate contents. The foregoing can explain the failure of heavy elements to accumulate in these soils even though they are affected by secondary dispersion of sulfide mineralizations. Thus, taking into account the edaphic characteristics of the soils it is possible to evaluate the incidence or not of effluent foci of this type.
Author´s Address:
(*):Dtº de Cristalografía y Mineralogía. Facultad de Ciencias 37008 Salamanca (Spain).
(**) Dtº de Química Agrícola, Geología y Geoquímica. Un. Autónoma. Madrid.
Henriksson, A.S.(*) & Malmgren, B.A.(**) (1997): Biogeographic and ecologic patterns in calcareous nannoplankton in the Atlantic and Pacific Oceans during the terminal Cretaceous. Stvd. Geol.Salmant., 33 (2): p. 17 40, 11 figs., 5 tables. Salamanca.
Key words: Cretaceous, Maastrichtian, Calcareous nannoplankton, Coccoliths, Biogeography.
ABSTRACT: Calcareous nannoplankton biogeography in the Cretaceous ocean has been analyzed from their floral composition at a time-slice spanning the upper parts of the Micula prinsii Zone (approximately the latest 10-60 kyr of the Cretaceous) at DSDP (Deep Sea Drilling Project) sites from low (16º) through middle (37º) paleolatitudes in both the Northern and the Southern Hemisphere. The study is based on relative abundance data of 44 species at Sites 356, 525A, and 527 from the South Atlantic, Sites 384 and 548A from the North Atlantic, and Site 465A from the Pacific Ocean.
No significant changes occurred in the nannoplankton flora at any of the sites during the terminal 10-60 kyr of the Maastrichtian. This suggests that a stable environment persisted through the end of the Cretaceous and that a sudden catastrophic event that affected the calcareous nannoplankton was the cause of their nearly total extinction at the end of the Cretaceous.
Most species of late Cretaceous calcareous nannoplankton are believed to be cosmopolitan and therefore to exhibit only minor biogeographical differences. Ecologic preferences could, however, be distinguished for various species. On the basis of a correspondence analysis two major floral assemblages were distinguished: one Tethyan and one Transitional assemblage. The Tethyan assemblage, dominating at Sites 465A, 356, 384, and 548A, was composed of a large group of almost all taxa encountered. The Transitional assemblage, dominating at Sites 525A and 527 (Walvis Ridge), was composed of Micula decussata, M. murus, Ceratolithoides aculeus, C. kamptneri, Lithraphidites quadratus, and Prediscosphaera majungae.
In addition, three subassemblages could be distinguished within the Tethyan assemblage. A Tethyan low-latitude subassemblage was distinguished at the North Pacific Site 465A due to enhanced abundances of four species, Watznaueria barnesae, Manivitella pemmatoidea, Loxolithus armilla, and Cylindralithus serratus. A warm Tethyan subassemblage was found at Site 356 in the South Atlantic with enhanced abundances of Discorhabdus ignotus, Corollithion exiguum, Zygodiscus erectus, Z. crux, Microrhabdulus undosus, Rhagodiscus asper, R. angustus, R. reniformes, and R. splendens. A shallow and cool Tethyan subassemblage was encountered at the North Atlantic Site 548A which had greater relative abundances of Nephrolithus frequens, Lucianorhabdus cayeuxii, Ahmuellerella octoradiata, Arkhangelskiella cymbiformis, Cretarhabdus surirellus, and Prediscosphaera majungae.
Author´s Address:
(*): Departamento de Geología, Facultad de Ciencias, 37008 Salamanca (España); also at Division of Applied Geology, LuleÕ Technical University, LuleÕ (Sweden)
(**): Department of Marine Geology, Earth Science Centre,
University of Göteborg, S 413 81 Göteborg (Sweden).
Suárez, E. (*); Fernández Amigot, J.A. (**); Moro, Mª.C. (***) & Botas, J. (**) (1997): Algunas respuestas radiométricas de las formaciones geológicas del Macizo Hespérico. Stvd.Geol.Salmant., 33 (3): p. 41-58. Salamanca.
Key words: Radiometrie, Airborne surveys, Geological Formations, Spanish Hercynian Belt, Spain.
[Some radiometric answers of the geological formations of the Spanish Hercynian Belt.].
ABSTRACT: The purpose of this work is to analyze in a surface of about 80.000 km2 of the Spanish Hercynian Belt some of the existing correlations between activity and geology. Approximately a 90% of the studied zone has been covered by radiometric airborne surveys with a grid of 1km using multichannel spectrometers for the Uranium, Thorium and Potassium discrimination. The total gamma accounts records have been translated to microRoentgen/hour at the soil level, using the air land correlations obtained by empirical procedures.
They have been accomplished numerous field works for the adquisition of data, as well as for the data elaboration into a geological mean known.
Author´s Address:
(*): Consejo de Seguridad Nuclear (CSN). C/. Justo Dorado, 11. 28040 Madrid
(**): Empresa Nacional del Uranio (ENUSA). C/. Santiago Rusiñol, 12. 28040 Madrid
(***): Universidad de Salamanca. Dto. de Geolog,ia. Facultad de Ciencias, Plaza de la Merced s.n. 37008 Salamanca.
Torcida, F. (*); Fuentes, C. (**); Izquierdo, L.A. (*); Montero, D. (*); Urién, V. (*) (1997): Dientes de Dinosaurios Terópodos (cf. Baryonyx) en el Weald de Burgos (España). Stvd.Geol. Salmant., 33 (4): p. 59-65, 2 figs. Salamanca.
Key words: Theropods, Weald, Burgos province, Spain.
[Teeth of Dinosaurs Theropods (cf. Baryonyx) in the Weald of the Burgos province (Spain).].
ABSTRACT: We present four different teeth of dinosaur theropods found in the province of Burgos, in facies Weald, Lower Cretaceous. The main difference whit other teeth of theropods is that these studied here have a simultaneous subcircular section and they have longitudinal crest in the lateral surfaces of their crown. The first similarity can be stablished whit teeth of genus Baryonyx.
Author´s Address:
(*): Colectivo Arqueológico-Paleontológico de Salas. Plaza Jesús Aparicio s/n. 09600 Salas de los Infantes (Burgos).
(**): I.E.S. Antonio Machado. Soria.
Fuente, M. S. de la (1997): Las tortugas pleistocenas del extremo meridional de la Provincia de Santa Fe, Argentina. Stvd.Geol.Salmant., 33 (5): p. 67-90; 8 figs. Salamanca.
Key words: Chelonii, Chelidae, Emydidae, Testudinidae, Late Pleistocene, Carcarañá river, Coronda river, Santa Fe, Argentina.
[The turtles of the Pleistocene of the southern Santa Fe Province, Argentina.]
ABSTRACT: The Late Pleistocene outcrops from Carcarañá and Coronda rivers, southern Santa Fe Province, Argentina, yielded a diverse fauna of turtles. A decorated chelid turtle (cf. Phrynops sp.), a small tortoise (Chelonoidis chilensis), a gigant tortoise (Chelonoidis sp.) (Carcarañá river) and an emydid turtle (cf. Trachemys sp.) (Coronda, river) are described.
Author´s Address:
Departamento Científico Paleontología Vertebrados. Facultad de Ciencias Naturales y Museo de La Plata. Paseo del Bosque S/N. 1900 La Plata, Argentina.
E mail: museo@isis.unlp.edu.ar
Fuente, M. S. de la (1997): Las tortugas terrestres gigantes (Chelonii: Testudinidae) del Mioceno tardío Plioceno del territorio argentino. Stvd.Geol.Salmant., 33 (6): p. 91-120. 17 figs, 3 tabls. Salamanca.
Key words: Chelonii, Testudinidae, Miocene, Pliocene, Andalhual, Monte Hermoso, Argentina.
[The giant land tortoises of the Late Miocene Pliocene of Argentina.]
ABSTRACT: The holotypes of ?Chelonoidis gallardoi (Rovereto, 1914) from the Araucanian s.s., Huayquerian (Late Miocene) at Andalhualá (Catamarca Province, Argentina) and ?C.australis (Moreno, 1889), from the Montehermosan (Early Pliocene) at Monte Hermoso (Buenos Aires, Province, Argentina) are described. Differential morphological traits between both specimens suggested specific differentiation. T. praestans Rovereto, 1914 is proposed as a synonym of ?Chelonoidis australis.
Author´s Address:
Departamento Científico Paleontología Vertebrados. Facultad de Ciencias Naturales y Museo de La Plata. Paseo del Bosque S/N. 1900 La Plata, Argentina.
E mail: museo@isis.unlp.edu.ar
Gutiérrez Alonso, G. (1997): La estructura del Antiforme del Narcea y su relación con los Mantos Occidentales de la Zona Cantábrica. Parte II: El sector oriental. Stvd.Geol.Salmant., 33 (7): p. 121-175. Figs. 21-39 + 5 anexos. Salamanca.
Key words: Variscan Belt, Iberian Massif, Narcea antiform, shear zones, foliation, mylonites, phyllonites, quartz petrofabrics.
[The Narcea Antiform Structure and its relation to the Western Cantabrian Zone thrust sheets. Part II: The Eastern Sector.].
ABSTRACT: In the eastern part of the Narcea Antiform, the Narcea Tectonic Window, only one cleavage developes, which is axial plane to vertical hinge folds. This foliation does not continue into the overlying unconformabily HerrerYa Formation, Cambrian in age. The contact between these two formations is a fault running alolng the unconformity plane, which may produce spaced foliations in the hangingwall rocks at high angle with precambrian rocks cleavage.Both, fault and cleavage are due to a variscan deformation event with deformation mechanisms partition at the unconformity, revealing different rheological behaviours and original orientations. The limit between these western and the eastern units is a major thrust.
The Somiedo Unit, the westernmost of the allochton ones in the Cantabrian Zone, has been known for long. It is formed by four main units, developed during the so called first thrust generation, which has a basal thrust, showing stiarcase trajectories, below the Lßncara formation, except in the westernmost part of the unit where it deepens into the precambrian rocks, being the only part of the Cantabrian Zone where the rooting of this units can be seen. This ramp produces a culmination over it and causes the antiform existence. Another generation of thrusts can be seen, the second one, which crosscuts the first ones and affects not only Somiedo Unit but Narcea Antiform as well. The second generation ones do not depict staircase trajectories, listric ones are common, and have much less displacement than the first generation ones. These listric reverse faults modify the first generation pattern, and causes Narcea Antiform re folding.
The relations between all these units are complex, and a tentative correlation between the two deformation phases at the WALZ, and the first thrust generation, at the CZ, has been done. The second thrusting stage is responsible for the final disposition of structures at the CZ and the WALZ.
Author´s Address:
Departamento de Geología, Universidad de Salamanca, 37008 Salamanca, España.
E mail: gabi@gugu.usal.es