M.A.Cuesta Ruiz-Colmenares: Los Pachynolophinae (Equoidea, Perissodactyla, Mammalia) del Eoceno de la Cuenca del Duero (Castilla y León, España). 21-64.
Abstract.- In the current paper the systematic study of Pachynolophinae (Equoidea, Perissodactyla, Mammalia) of the Duero Basin (Castilla y León, Spain) is made. Remains belonging to this subfamily, less abundant than other Perissodactyla groups, are present in seven localities: Casaseca, Corrales, Jambrina and El Viso-Sanzoles (middle part of the middle Eocene, MP 13-14, Zamora province), Caenes and San Morales (upper part of the middle Eocene, MP 16, Salamanca province) and Mazaterón (middle Eocene-upper Eocene, MP 16-17, Soria province). Pachynolophus is present in Casaseca and El Viso-Sanzoles, which are the only Spanish localities for this genus with somewhich of the subpyrenean area. The genus Paranchilophus, previously only known in Llamaquique (0viedo, España), is well documented in Mazaterón (Paranchilophus remyi) and poorly represented in Caenes. In San Morales, with cf. Anchilophus, and in Jambrina and Corrales, with forms of uncertain generic determination, Pachynolophinae are documented by very fragmentary remains.
E. Alonso Castro & M. López Plaza: Estudio petrológico y estructural del área antiformal del oeste de Pereruela (Provincia de Zamora). 65-100.
Abstract.- The present work reports on a mapping, petrographic and structural study of the area of the Pereruela antiform (central Zamora). Petrographic and geoche-mical characterization of the gneisses of the core antiform is emphasized, as well as the formation of tourmaline. From a structural point of view, this area displays an outstand-ing variability, because the Pereruela-Villalcampo shear zone is overlapped on the phase III hercynian antiform. Conventionally, six sectors of different petrological and structural meaning are established; so Northwards a shistose and quarzitic sector, with likely extensional crenulation cleavage, follows Sayago anatectic granite, of which pelitic country rock appears phyllonitized. Concerning metamorphism it is worthy to note the subparallel geometry of M1-metamorphism isograds, with chloritoid, garnet and relict staurolite, with regard to M2-metamorphism isograds, with andalusite, cordierite and prismatic sillimanite. The Sayago granite boundary is reworked by the shearing, so its contact becomes more parallel to these metamorphic isograds as well as in relation to the mega-structures of the country rock. On the other hand, the fluids generated by the anatectic process are mobilized by shearing towards a peripheral area of the core antiform; consequently, tourmalinites and a great quantity of Sn-W rich veins and aplo-pegmatitic segregations are developped. In particular, a preference for boron in plagioclase-biotite bearing gneisses and in sillimanite-biotite bearing schists can be deduced. Furthermore, the appearance of tourmaline in the leucocratic granites could be seen as a subsolidus evolution during shearing, in the same way as common myrmekites of the feldspars of the microglandular gneisses and porphyritic Sayago-type granite.
Richard Köhler: An Eocene turtle humerus (Dermochelyidae, Psephophorus) from New Zealand. 101-106.
Abstract.- The find of a late Lutetian to early Bartonian humerus extends the geographic range of Psephophorus into the Southern Pacific. Comparisons to other Dermochelyid humeri show some similarities with Psephophorus eocaenus Andrews, 1901 (as described and figured by him in 1901 and 1906). But the New Zealand find is too different to be included in the species eocaenus.
Marcelo S. de la Fuente: Descripción de nuevos especímenes y relaciones filogenéticas de Chelonoidis gringorum (Simpson, 1942)(Chelonii: Testudinidae) del Mioceno temprano de Patagonia Central, Argentina. 107-132.
Abstract.- New specimens referred to Chelonoidis gringorum (Simpson, 1942) are described. The tortoises were found in outcrops of the Sarmiento Formation on the south side of the Chubut Valley, between Gaiman and Dolavon (Chubut Province, Argentina). An analysis of shell traits variation on Chelonoidis gringorum and the extant close relatives species was done. Finally a tentative phylogenetic hypothesis about the relationships between Ch.gringorum and other south american tortoises is proposed. The clade Chelonoidis gringorum-?Chelonoidis sp. from Quebrada Saguayo (Fm. Petaca-Deseadan-Bolivia) is considered the sister group of the extant South American Testudininae.
E. Jiménez Fuentes: Nota preliminar sobre nuevos ejemplares de quelonios fósiles del Plioceno de Las Higueruelas (Campo de Calatrava: Ciudad Real). 133-138.
Abstract.- New fragmentary specimens of giant Testudinidae from the Las Higueruelas fossil site (Pliocene, Campo de Calatrava, Ciudad Real province, Spain), may be classified in three different size ranges: small (1,2 to 1,5 m), medium (1,5 to 1,8 m) and large (1,7 to 2 m). All the features characterizing the adult males are related to those concerning the largest size; the characters related to the smallest size probably correspond to female individuals. It is suggested that this would be due to mating habits instead of to sexual dimorphism.
P. Barba & J.R. Colmenero: Estratigrafía y sedimentología de la sucesión Westfaliense del borde sureste de la Cuenca Carbonífera Central (Zona Cantábrica, N de España). 139-204.
e-mail Pedro Barba
Abstract.- The Westphalian succession of the Central Coal Basin depicts great lateral and vertical facies variability, with frequent terrigenous and carbonate beds in a predominantly mudstone series. The former are commonly found in the lower part (Lena Group) and the latter acompaigned with economic coal seams, in the upon unit (Sama Group). According to these stratigraphic and some structural criterium, the Central Coal Basin has been divided into subbasins or sectors with different litostratigraphic series. From the stratigraphic correlation of the studied localities and the lithology percentage maps, there is an eastward thinning of the carboniferous serie (from 6000 to less than 2000 m) and an increase on limestone content.
The facies description and interpretation allows the correlation of several sedim-entary environments, from coastal to deep ones: a) The deltaic ones are: coastal alluvial fans, braided plain deltas and fluvial deltas. b) In the shallow sea environments both carbonate and terrigenous shelf are distinguished. c) In the deep sea environments, external platform and a carbonate slope and submarine fans.
The studied Bashkirian-Moscovian shows a regressive macrosecuencia, prograd-ational, coarsening upward of alocyclic origin. This can be separated into five mesoscale sequences due to tectonic impulses and to possibility eustatic sea incursions. The cyclothems are related with the progradation and abandon of deltaic lobes of autocyclic or alociclyc origin.
The cantabrian coal basin is considerated as a foreland basin, where depocentre mobility forwards the east, as a result of the tectonic deformation front. Subsidence curve in differents sectors depict low slopes during Tournaisiense-Viseense, considered preor-ogenic and higher slopes (sinorogenic) of Namurian-Westphalian age.
During Bashkirian times there is a foredeep, a forebulge with local condensed sedimentation at the "tras umbral" basin. Later, these is an uniformation stage, during Moscovian, with shallow sea conditions. Vereisky and Kashirsky are characterized by stacked delta plain episodes, in the proximal sectors, and terrigenous shelf with carbonate shelf episodes in the external parts. During upper Kashirsky there is an irruption of important deltaic systems, braided plain type and most important carbonate shelf deposits are installed at the western border. A new platform expansion takes place during Kashirsky-Podolsky. The sedimentary basin undergoes an important tectonic reduction at Podolsky-Myachkovsky as a result of the orogenic deformation front advance. The irruption of alluvial sediments in the basin prograde over a transitional shallow marine environment giving rise to coastal alluvial fans. Towards the basin interior, they are substituted by braided plain deltas and fluvial deltas alternating with shallow marine episodes either terrigenous or carbonatic dominating in the most external sectors of the basin.
G. Gutiérrez Alonso: La estructura de la parte norte de la ventana tectónica del Narcea (Zona Cantábrica, NO de España). 205-221.
e-mail Gabriel Gutiérrez-Alonso
Abstract.- The rear part of the Somiedo thrust nappe, in the eastern limb of the Narcea Tectonic Window, depicts two superimposed thrust systems with their related folds. The first group of thrusts comprises the basal decollement of the Somiedo nappe, below the Láncara Formation, and its related imbricated and duplex thrust systems. The second group crosscuts the first one and most of the folds seen are related to it. Cross folding is present, produced by the interference of frontal and lateral culminations related to the second thrust generation. The superposition of these structures gave rise to the Narcea culmination, where the precambrian rocks outcrop. Its northern periclinal closure is caused by radial folds related to the second thrust group.