Alberto Saez

Two Palaeogene fluvial fan systems linked to the south Pyrenean margin are recognized in the eastern Ebro Basin: the Cardona–Suria and Solsona–Sanauja fans. These had radii of 40 and 35 km and were 800 and 600 km2 in area respectively. During the Priabonian to the Middle Rupelian, the fluvial fans built into a hydrologically closed foreland basin, and shallow lacustrine systems persisted in the basin centre. In the studied area, both fans are part of the same upward-coarsening megasequence (up to 800 m thick), driven by hinterland drainage expansion and foreland propagation of Pyrenean thrusts. Fourteen sedimentary facies have been grouped into seven facies associations corresponding to medial fluvial fan, channelized terminal lobe, nonchannelized terminal lobe, mudflat, deltaic, evaporitic playa-lake and carbonate-rich, shallow lacustrine environments. Lateral correlations define two styles of alluvial-lacustrine transition. During low lake-level stages, terminal lobes developed, whereas during lake highstands, fluvial-dominated deltas and interdistributary bays were formed. Terminal lobe deposits arecharacterized by extensive (100–600 m wide) sheet-like fine sandstone beds formed by sub-aqueous, quasi-steady, hyperpycnal turbidity currents.
Sedimentary structures and trace fossils indicate rapid desiccation and subaerial
exposure of the lobe deposits. These deposits are arranged in
coarsening–fining sequences (metres to tens of metres in thickness) controlled by a combination of tectonics, climatic oscillations and autocyclic sedimentary processes. The presence of anomalously deeply incised distributary channels associated with distal terminal lobe or mudflat deposits indicates rapid lake-level falls. Deltaic deposits form progradational coarsening-upward sequences (several metres thick) characterized by channel and friction-dominated mouth-bar facies overlying white-grey offshore lacustrine facies. Deltaic bar deposits are less extensive (50–300 m wide) than the terminal lobes and were also deposited by hyperpycnal currents,although they lack evidence of emergence. Sandy deltaic deposits accumulated locally at the mouths of main feeder distal fan streams and were separated by muddy interdistributary bays; whereas the terminal lobe sheets expand from a series of mid-fan intersection points and coalesced to form a more continuous sandy fan fringe.

[ES] Se caracterizan las facies de una sucesion de 2.250 m de potencia de sedimentos carboniferos turbiditicos de la parte central del Priorato (zona de las vilellas-Poboleda). En 10s materiales paleozoicos de este area se distinguen tres unidades IitoestratigrAficas carboniferas que integran el Complejo Turbidítico del Prioraro y que yacen discordantes sobre 10s materiales del Devdnico medio-superior (unidad 1). Los materiales de la unidad inferior (unidad 2) se depositaron en un ambiente de talud - apron y constan fundamentalmente de areniscas que intercalan niveles deslizados de liditas, calizas y areniscas. Los depdsitos de las unidades 3 y 4 rnuestran diversas asociaciones de facies tipicas de ambientes de abanico submarino profundo. La unidad 3 muestra facies de llanura de cuenca y depositos arenosos de un canal intercalado. La unidad 4 esta constituida por tres megasecuencias negativas que corresponden a otros tantos episodios de progradacion de un sistema de lóbulo de abanic...

From the Tertiary As Pontes basin (Galicia, Spain) the first reptilian remains (Crocodylia, Diplocy nodon s.l.) are described. Together with these findings palaeobotanical data (pollen, fructífications) result from the same sediment sampled. They are used for stratigraphical and palaecological interpretations. Due to these palaeontological informations one might interprete the lower As Pontes lignites as belonging to the Paleogene, most probably Oligocene. Nevertheless complementary data are needed lo confirm this stratigraphic contributíon.

Dans la région de la basse vallée du Loa, il y a eu deux étapes extensives pendant le Tertiaire. La Cordillera de la Costa est le résultat de la superposition des failles normales appartenant à ces deux phases. Sa limite avec la vallée longitudinale a été formée pendant la première phase (Oligocène (?)-Miocène) et son bord occidental, la falaise côtière, pendant la seconde (Miocène-Pliocène). L'activité tectonique extensive s'est donc déplacée de l'est vers l'ouest durant le Tertiaire. (Résumé d'auteur)

ABSTRACT Marine Isotope Stage (MIS) 3 climate has been globally characterized by the occurrence of millennial-scale climate variations defined over North Atlantic as Dansgaard-Oeschger and Heinrich events. Despite climate variability has been broadly explored over North Atlantic records, the response of the tropical and subtropical latitudes, especially in the Southern Hemisphere, still remains as a matter of debate. Rano Aroi peat record (Easter Island, Chile, 27°S) provides a unique opportunity to understand Southern Pacific atmospheric and oceanic changes during these stadial-interstadial transitions because of its exceptional location on the interplay of the South Pacific Convergence Zone (SPCZ), the Intertropical Convergence Zone (ITCZ), the South Pacific Anticyclone (SPA) and the Southern Westerlies (SW). Rano Aroi record contains 8 main enhanced precipitation events between 70 and 40 kyr BP that can be correlated with the timing of Heinrich events 5, 5a and 6 as well as other cold stadials. These humid events are also present in other Southern Hemisphere continental sites and correspond to dry periods on Northern Hemisphere records. This opposite hydrologic trend has been explained by the latitudinal migration of ITCZ and has been supported by several climatic models. As Easter Island precipitation is mainly dependent on SPCZ storm track belt activity, we suggest that the southern migration of the ITCZ is associated to an expansion of SPCZ to the east. This process should be intimately related to a weakening of the Walker circulation, which is further supported by an estimation of d18Osw gradient along the equator for the same time period. Consequently, atmospheric and oceanic responses during these cold stadials and Heinrich events might lead to a configuration that resembles the warm ENSO state over Southern Pacific, as previously suggested by some global climatic models. Rano Aroi record clearly points out that shifts in hydrological cycle in tropical Southern Hemisphere have been abrupt in response to the MIS 3 climate variability, a pattern which is in contrast to the typical gradual changes shown by several southern hemisphere records. This points to a very rapid atmospheric reorganization at low and medium latitudes in front to a more progressive oceanic heat redistribution lead by the bipolar seesaw.

The Ebro Basin is a triangular shaped foreland basin surrounded by three alpine ranges: the Pyrenees to the north, the Iberian Range to the SW and the Catalan Coastal Range to the SE. During the early Paleocene started the development of the Ebro Basin by flexural subsidence related to the growth of its margins as a consequence of the continental collision of Iberia and Europe. Connection of the Ebro Basin with the open sea was maintained until late Eocene, when ongoing convergence along the Pyrenean margin lead to the final closure of its western connection with the Atlantic Ocean. Since then, a long endorheic period of uninterrupted continental sedimentation leads to the accumulation of a thick sequence composed by alluvial and lacustrine facies. In foreland basins, tectonics plays a fundamental role in the sedimentation, by generating relief in the margins and accommodation space in the basin. Therefore, it is generally assumed that the main sedimentary breaks have a tectonic ori...

The As Pontes basin (12 km2), NW Iberian Peninsula, is bounded by a double restraining bend of a dextral strike-slip fault, which is related to the western onshore end of the Pyrenean belt. Surface and subsurface data obtained from intensive coal exploration and mining in the basin since the 1960s together with additional structural and stratigraphic sequence analysis allowed us