Abstrakt: Le niveau biochronologique de Beaulieu est défini par quatre localités, contemporaines du volcanisme daté de -17,5 ñ 0,3
Ma. et dont deux sont en corrélation avec un dépôt marin daté des biozones N6 + N7. La microfaune (rongeurs et lagomorphes) indique
un niveau élevé dans la période du «cricetid
vacuum» (zone B d’AGUILAR (1982) ou MN 3 (DE BRUIJN et al., 1992), probablement
plus jeune que Wintershof-West, tandis que la macrofaune indique un âge sub-contemporain. L’âge radiométrique et la polarité
normale du basalte permettent une discussion sur la limite MN3/MN4.
[RESUMEN]
El nivel biocronológico de Beaulieu está definido por cuatro localidades, contemporáneas del volcanismo cuya edad es -17,5 ñ 0,3 Ma. y donde dos están correlacionadas con un depósito marino de las biozonas N6 + N7. La microfauna (roedores y lagomorfos) indican un nivel alto en el periodo del «cricetid vacuum» (zona B de AGUILAR (1982) o MN 3 (DE BRUIJN et al., 1992), probablemente más joven que Winthershof-West, aunque la macrofauna indica una edad casi contemporánea. La edad radiométrica y la
polaridad normal del basalto permiten discutir la límite MN3/MN4.
[ABSTRATC]
Beaulieu’s biochronological level is defined by four localities, contemporaneous of the volcanism dated -17,5 ñ 0,3 My.,among which two of them are in correlation with marine deposits dated in biozones N6 + N7. The microfauna (rodents and lagomorphs) indicates a high level in the time interval named the «cricetid vacuum « (zones B of AGUILAR (1982) or MN 3 (DE BRUIJN et al., 1992), probably younger than Wintershof-West, while the macrofauna is indicating their sub-contemporaneity. The radiometric age and the normal polarity of the basalt allow to discuss about the MN3 / MN4 boundary.
Stichwort: Mammifères, Datation radiométrique, Miocène inférieur, Sud de la France, Limite MN3/MN4, Mamíferos, Datación radiométrica, Mioceno inferior, Sur de la Francia, Límite MN3/MN4, Mammals, Radiometric data, Early Miocene, South of France, MN3/MN4 boundary
Abstrakt: Le niveau biochronologique de Beaulieu est défini par quatre localités, contemporaines du volcanisme daté de -17,5 ñ 0,3 Ma. et dont deux sont en corrélation avec un dépôt marin daté des biozones N6 + N7. La microfaune (rongeurs et lagomorphes) indique un niveau élevé dans la période du «cricetid
vacuum» (zone B d’AGUILAR (1982) ou MN 3 (DE BRUIJN et al., 1992), probablement plus jeune que Wintershof-West, tandis que la macrofaune indique un âge sub-contemporain. L’âge radiométrique et la polarité normale du basalte permettent une discussion sur la limite MN3/MN4.
[ABSTRACT]
Beaulieu’s biochronological level is defined by four localities, contemporaneous of the volcanism dated -17,5 ñ 0,3 My., among which two of them are in correlation with marine deposits dated in biozones N6 + N7. The microfauna (rodents and lagomorphs) indicates a high level in the time interval named the «cricetid vacuum « (zones B of AGUILAR (1982) or MN 3 (DE BRUIJN et al., 1992), probably younger than Wintershof-West, while the macrofauna is indicating their sub-contemporaneity. The radiometric age and the normal polarity of the basalt allow to discuss about the MN3 / MN4 boundary.
[RESUMEN]
El nivel biocronológico de Beaulieu está definido por cuatro localidades, contemporáneas del volcanismo cuya edad es -17,5 ñ 0,3 Ma. y donde dos están correlacionadas con un depósito marino de las biozonas N6 + N7. La microfauna (roedores y lagomorfos) indican un nivel alto en el periodo del «cricetid vacuum» (zona B de AGUILAR (1982) o MN 3 (DE BRUIJN et al., 1992), probablemente más joven que Winthershof-West, aunque la macrofauna indica una edad casi contemporánea. La edad radiométrica y la polaridad normal del basalto permiten discutir la límite MN3/MN4.
Stichwort: Mammifères, Datation radiométrique, Miocène inférieur, Sud de la France, Limite MN3/MN4, Mammals, Radiometric data, Early Miocene, South of France, MN3/MN4 boundary, Mamíferos, Datación radiométrica, Mioceno inferior, Sur de la Francia, Límite MN3/MN4.
Abstrakt: En este trabajo se publica el catálogo de una colección de modelos cristalográficos de terracota, atribuidos a Jean Baptiste Romé de l’Isle. Este gran mineralogista del siglo XVIII, considerado como uno de los fundadores de la Cristalografía, realizó varias colecciones similares, para ofrecerlas como reclamo publicitario junto a su libro “Cristallographie”,
que publicó en 1783. En la actualidad se conoce la existencia de otras cinco colecciones más que se conservan en diferentes museos europeos.
Todas ellas fueron moldeadas a mano, con arcilla, y cocidas en la Real Fábrica de Porcelana de Sèvres. La colección del Departamento
de Cristalografía de la Universidad Complutense consta de 186 piezas y entre ellas hay reproducciones de minerales,
maclas y representantes de los Sistemas Cristalinos. Es posible que en un principio fuera más numerosa, pero debido a las múltiples
vicisitudes sufridas a lo largo de los años (robos, extravíos, ...) puede que se hayan perdido algunos ejemplares.
Stichwort: Romé de L’Isle, Sólidos cristalográficos, Modelos de terracota, Gabinetes mineralógicos, Romé de L’Isle, Crystal models, Terracotta models, Mineralogical cabinets
Descriptors: Cueva de altura; Murciélagos; Actual y Pleistoceno superior; Evolucion climática; Mountain cave; Bats; Recent & Late Pleistocene; Climatic evolution
Abstrakt: Based on new radiometric data, a Pre-Cañadas volcanic building of 3.5-3.0 Ma has been defined. This
new building is mainly compared of basaltic rack cropping out in several gorges to the S of Cañadas
Building, inside of the «Pared de Las Cañadas», «Boca de Tauce», and «La Grieta» and «La Angostura»
valleys. Estimated
minumum diameter and maximun high is 23 Km and 2300 m respectively. The
destruction of this volcanic structure could contribute in the formation of the volcanic breccia ocurring
underneath the Tigaiga massif.
Abstrakt: Many felsic pyroclastic units of various types are exposed in different sectors of Tenerife. New 40Ar/39Ar determinations allow them to be placed more precisely in the general volcano-stratigraphic succession. According to geographic distribution, stratigraphic position and isotopic ages, four main pyroclastic
phases may be identified. The first, San Juan de la Rambla phase (2.1 Ma), is only known in the north of Tenerife in the Tigaiga massif. The second, Adeje phase (1.8–1.5 Ma), is most completely developed in the southwest of the island, but occasionally occurs in the other sectors. The third, Las Américas phase (1 Ma), is only presently known in the southern region. The fourth, Bandas del Sur phase (0.7–0.15 Ma), is essentially exposed in the southeast sector. The results of this work emphasise the complexity of the pre-1-Ma eruptive history of Tenerife and underline the fact that explosive volcanic activity has taken place for at least the last 2 Ma. Vertical collapse structures have developed as a result of pyroclastic flow activity and these may be as old as 1.6–1.8 Ma, therefore much older than generally considered. The precise location of calderas is difficult to ascertain as a result of the repeated lateral flank collapse during the construction of the Cañadas volcano.
Abstrakt: Heat flow calculations based on geological and/or geophysical indicators can help to constrain the thickness,
and potentially the geochemical stratification, of the martian crust. Here we analyze the Warrego
rise region, part of the ancient mountain range referred to as the Thaumasia highlands. This region has
a crustal thickness much greater
than the martian average, as well as estimations of the depth to the brittle–
ductile transition beneath two scarps interpreted to be thrust faults. For the local crustal density
(2900 kg m3) favored by our analysis of the flexural state of compensation of the local topography,
the crustal thickness is at least 70 and 75 km at the scarp locations. However, for one of the scarp locations
our nominal model does not obtain heat flow solutions permitting a homogeneous crust as thick as
required. Our results, therefore, suggest that the crust beneath the Warrego rise region is chemically
stratified with a heat-producing enriched upper layer thinner than the whole crust. Moreover, if the mantle
heat flow (at the time of scarp formation) was higher than 0.3 of the surface heat low, as predicted by
thermal history models, then a stratified crust rise seems unavoidable for this region, even if local heatproducing
element abundances lower than average or hydrostatic pore pressure are considered. This
finding is consistent with a complex geological history, which includes magmatic-driven activity.
