Fossil birds from the Late Cretaceous Los Alamitos Formation,Río Negro Province,Argentina

In this note we report new avian remains from the Late Cretaceous Los Alamitos Formation (Campanian-Maastrichtian) at the Los Alamitos locality, Río Negro Province, Argentina. Isolated remains referable to indeterminate Aves, ?Patagopterygiformes, indeterminate Ornithurae, cf. Hesperornithes and cf. Neornithes are described and discussed. The new genus and species Alamitornis minutus is erected to include a minute-sized and gracile bird, probably related to the non-volant ratite-like bird Patagopteryx. If correctly identified, the record of Hesperornithes may be the first for this group in the Southern Hemisphere. The Los Alamitos paleoavifauna represents one of the most diverse fossil bird assemblage from the Mesozoic of Gondwana known to date.     

Simple procedure to simulate karstic aquifers

A procedure to simulate karstic aquifers is presented. It is based on a simulation of spring discharge using precipitation and, where necessary, temperature as input data. The karstic aquifer system is considered to be divided into three zones: the surface zone, the unsaturated zone (UZ) and the saturated zone (SZ). Each of these is described by a transfer function that determines the water supplied from the overlying zone. Water loss through evapotranspiration is calculated empirically and subtracted from the total precipitation in order to obtain the effective infiltration into the UZ. The transfer function characterizing the UZ can be expressed as a convolution function. The UZ acts as a buffer, delaying effective infiltration into the SZ. Water discharge from the SZ is described by the recession function of the spring, and this becomes the transfer function that characterizes the emergence of water from the SZ. The model permits the simulation of the influence of pumped abstractions from the system by a simple modification of the transfer functions involved. Copyright © 2007 John Wiley & Sons, Ltd.     

Homographic solutions in the planar <Emphasis Type="Italic">n</Emphasis> + 1 body problem with quasi-homogeneous potentials

We prove that for generalized forces which are function of the mutual distance, the ring n + 1 configuration is a central configuration. Besides, we show that it is a homographic solution. We apply the above results to quasi-homogeneous potentials.     

Mesoarchean sanukitoid rocks of the Rio Maria Granite-Greenstone Terrane,Amazonian craton,Brazil

The Archean sanukitoid Rio Maria Granodiorite yielded zircon ages of ～2.87 Ga and is exposed in large domains of the Rio Maria Granite-Greenstone Terrane, southeastern Amazonian craton. It is intrusive in the greenstone belts of the Andorinhas Supergroup, in the Arco Verde Tonalite and Caracol Tonalitic Complex (older TTGs). Archean potassic leucogranites, younger TTGs and the Paleoproterozoic granites of Jamon Suite are intrusive in the Rio Maria Granodiorite.The more abundant rocks of the Rio Maria Granodiorite have granodioritic composition and display medium to coarse even-grained textures. These rocks show generally a gray color with greenish shades due to strongly saussuritized plagioclase, and weak WNW-ESE striking foliation. The significant geochemical contrasts between the occurrences of Rio Maria Granodiorite in different areas suggest that this unit corresponds in fact to a granodioritic suite of rocks derived from similar but distinct magmas. Mingling processes involving the Rio Maria Granodiorite and similar mafic to intermediate magmas are able to explain the constant occurrence of mafic enclaves in the granodiorite.The associated intermediate rocks occur mainly near Bannach, where mostly quartz diorite and quartz monzodiorite are exposed. The dominant rocks are mesocratic, dark-green rocks, with fine to coarse even-grained texture. The Rio Maria Granodiorite and associated intermediate rocks show similar textural and mineralogical aspects. They follow the calc-alkaline series trend in some diagrams. However, they have high-Mg#, Cr, and Ni conjugate with high contents of large ion lithophile elements (LILEs), typical of sanukitoids series. The patterns of rare earth elements of different rocks are similar, with pronounced enrichment in light rare earth elements (LREEs) and strong to moderate fractionation of heavy rare earth elements (HREEs).Field aspects and petrographic and geochemical characteristics denote that the granodiorites and intermediate rocks have sanukitoid affinity. However, geochemical data suggest that the intermediate rocks and the granodiorites are not related by a fractional crystallization process. It is concluded that the intermediate rocks derived from similar sources to the granodiorites, but probably result from a higher degree of melting, being both cogenetic, but not comagmatic rocks.Mineralogical aspects associated with experimental evidence suggest that the Rio Maria Granodiorite magma was relatively water-enriched (>4 wt.%), explaining the presence of hornblende at the liquidus and the absence of clinopyroxene and orthopyroxene in the studied rocks. The occurrence of well-preserved magmatic epidote crystals, admitting that the Rio Maria Granodiorite was emplaced at shallow crustal levels, points to a rapid ascent of the Rio Maria Granodiorite magma.     

Intramontane basin development related to contractional and extensional structure interaction at the termination of a major sinistral fault: The Huércal-Overa Basin (Eastern Betic Cordillera)

Among the classical minor structural associations on the termination of transcurrent faults are horsetail splays formed by reverse, normal or strike-slip faults developing duplexes. However, temporal and spatial coexistence of contractional and extensional structures is very rarely documented. We discuss the relationships of contractional and extensional structures and associated sedimentary depocenters at the termination of a major strike-slip fault in the Eastern Betic Cordillera. Field mapping, kinematic fault analysis, paleostress determination and gravity prospecting in the Huércal-Overa Basin, at the southern termination of the NE–SW Alhama de Murcia transcurrent fault (AMF), are used to establish the relationships of tectonic structures and associated sedimentary depocenters. Here, ENE–WSW and WNW–ESE folds interact with two sets of normal faults having the same orientation as well as ENE–WSW reverse faults. Progressive unconformities associated with folds reveal that the beginning of the AMF activity occurred in the Tortonian. The folds progressively grew and rotated from ENE–WSW up to WNW–ESE close to the transcurrent fault. We propose that the development of the normal faults developed during short-term episodes characterized by vertical major stress axis and are, in turn, related to gravitational instability linked to the thickening of a crust relatively hot at depth. This setting may have become predominant in between the main activity, compressive pulses along transcurrent faults.     

A kinetic approach for simulating redox‐controlled fringe and core biodegradation processes in groundwater: model development and application to a landfill site in Piedmont,Italy

A three‐dimensional model for predicting redox controlled, multi‐species reactive transport processes in groundwater systems is presented. The model equations were fully integrated within a MODFLOW‐family reactive transport code, RT3D. The model can simulate organic compound biodegradation coupled to different terminal electron acceptor processes. A computational approach, which uses the spatial and temporal distribution of the rates of different redox reactions, is proposed to map redox zones. The method allows one to quantify and visualize the biological degradation reactions occurring in three distinct patterns involving fringe, pseudo‐core and core processes. The capabilities of the numerical model are demonstrated using two hypothetical examples: a batch problem and a simplified two‐dimensional reactive transport problem. The model is then applied to an unconfined aquifer underlying a leaking landfill located near the city of Turin, in Piedmont (Italy). At this site, high organic load from the landfill leachate activates different biogeochemical processes, including aerobic degradation, denitrification, manganese reduction, iron reduction, sulfate reduction and methanogenesis. The model was able to describe and quantify these complex biogeochemical processes. The proposed model offers a rational framework for simulating coupled reactive transport processes occurring beneath a landfill site. Copyright © 2008 John Wiley & Sons, Ltd.     

Chemical and isotopic assessment in volcanic thermal waters: Cases of Ischia (Italy) and São Miguel (Azores,Portugal)

Isotopic fractionation of ¹⁰B/¹¹B provides a sound tool for identifying hydrogeochemical processes in complex areas, owing to its ability to discriminate between various scenarios. In addition, the occurrence of boron as a minor element in areas of active volcanism allows its use in comparison with concentrations of other conservative or non‐conservative ions. This allows the detection of water mixtures of diverse origin and temperature, deep or shallow, including fresh water, seawater and even brines. This tool was applied in studies of the volcanic islands of Ischia and São Miguel, across widely differing geographical and climatic contexts. Five groups of waters have been identified in Ischia Island: marine, transition, hot carbonated, cold carbonated and fresh waters. For São Miguel Island the identified groups are cold carbonic, hot carbonic, boiling and acidic boiling waters. Copyright © 2008 John Wiley & Sons, Ltd.     

The pollen counts as bioindicator of meteorological trends and tool for assessing the status of endangered species: the case of Artemisia in Sierra Nevada (Spain)

This study sought to analyse the effects of climate change on Artemisia species growing in Sierra Nevada, a high mountain range in the south-east of the Iberian Peninsula, using pollen counts as a bioindicator. The study also examined the impact of Recovery Programmes implemented for the most endangered of these species. Analysis of historical Artemisia pollen-data series from 1992 to 2011 showed that flowering took place between late July and late September, but the trend towards higher summer temperatures detected over the series as a whole appeared to have delayed the start of flowering and brought forward the end of flowering, thus prompting a shortening of the season. A trend was also observed towards a delayed peak pollen period, together with a significant decline in the Annual Pollen Index, which was significantly influenced by rainfall over the months immediately prior to flowering. Recovery Programmes implemented for three species—Artemisia granatensis, A. alba subsp. nevadensis and A. umbelliformis—involved conservation measures including direct seeding and planting of seedlings. From the outset, these programmes led to a recovery of the Pollen Index, especially when using germinated seedlings, which adapted better than seeds to environmental conditions. In conclusion, pollen records proved to be a useful tool for assessing the status of endangered species.     

Paleoenvironmental reconstruction of a Late Quaternary lagoon system in southern Brazil (Jaguaruna region,Santa Catarina state) based on multi‐proxy analysis

This paper provides a paleoenvironmental reconstruction of a Late Quaternary lagoon system in the Jaguaruna region of Santa Catarina state, southern Brazil. Integrated results of bulk sedimentary organic matter characterization (δ¹³C, δ¹⁵N and C/N), microfossil (pollen and diatom) and grain‐size analysis from three shallow cores (～2.5 m depth) allowed us to propose an evolving paleogeographic scenario in this coastal region for the last ca. 5500 cal a BP. The lagoonal system in this area was more extensive during the mid‐Holocene than today, with a gradual and continuous lagoon–sea disconnection until the present. We add to the debate regarding relative sea‐level (RSL) variations for the Brazilian coast during the Holocene and discuss the importance of sedimentary dynamics for interpreting changes in coastal ecosystems. The multi‐proxy analysis suggests that changes in coastal ecosystems could be directly related to local sedimentary processes, which are not necessarily linked to RSL fluctuations and/or to climatic variations. Copyright © 2011 John Wiley & Sons, Ltd.     

Evaluating Duero's basin (Spain) response to the NAO phases: spatial and seasonal variability

In this study, we analysed the influence of the North Atlantic Oscillation (NAO) on the hydrological response of the Duero River (central Spain) and its tributaries. We identified the positive and negative phases of the winter NAO for the period 1961–2006 and related precipitation and river discharge anomalies. Significant differences in precipitation and river discharge were found between the positive and negative NAO phases with negative anomalies (dry conditions) during positive NAO periods, and positive anomalies (wet conditions) during negative NAO periods. Marked differences were also found in the precipitation and river discharge response times to the NAO episodes, with an immediate response for precipitation but a lag and more sustained response for river discharges. Differing patterns were also identified in the response of river discharge to the NAO throughout the Duero basin. The physical characteristics of watersheds (including area, altitude and permeability explained most of the differences in the timing and magnitude of anomalies in the river discharge in response to the NAO. The findings highlight the great variability in the hydrological response of rivers to the NAO episodes. Copyright © 2010 John Wiley & Sons, Ltd.