Miocene sediments from Foz da Fonte and Penedo sections (Lower Tagus basin): clay minerals and isotopic data

Eight depositional sequences (DS) delimited by regional disconformities had been recognized in the Miocene of Lisbon and Setúbal Peninsula areas. In the case of the western coast of the Setúbal Peninsula, outcrops consisting of Lower Burdigalian to Lower Tortonian sediments were studied. The stratigraphic zonography and the environmental considerations are mainly supported on data concerning to foraminifera, ostracoda, vertebrates and palynomorphs. The first mineralogical and geochemical data determined for Foz da Fonte, Penedo Sul and Penedo Norte sedimentary sequences are presented. These analytical data mainly correspond to the sediments' fine fractions. Mineralogical data are based on X-ray diffraction (XRD), carried out on both the less than 38 nm and 2 nm fractions. Qualitative and semi-quantitative determinations of clay and non-clay minerals were obtained for both fractions. The clay minerals assemblages complete the lithostratigraphic and paleoenvironmental data obtained by stratigraphic and palaeontological studies. Some palaeomagnetic and isotopic data are discussed and correlated with the mineralogical data. Multivariate data analysis (Principal Components Analysis) of the mineralogical data was carried out using both R-mode and Q-mode factor analysis.

Uppermost Miocene Lamniform Selachians (Pisces) from the Alvalade basin (Portugal)

This paper deals with Lamniform teeth collected in deposits from the Esbarrondadoiro Formation, Alvalade Basin in Southern Portugal. The following genera were recognized: Carcharias, Pseudocarcharias, Alopias, Isurus and Carcharocles. The species Carcharias acutissima is by far the most predominant, all other taxa being rare or very rare. This situation points to neritic, tropical to subtropical, rather shallow waters not far away from the coast. This is corroborated by the rarity of the associated, mainly pelagic, taxa. The ratio between C. acutissima and the remaining Lamniforms as a whole is markedly uneven between Esbarrondadoiro and the localities of Santa Margarida and Vale de Zebro. This suggests quite different environmental conditions, a matter that will require a more thorough examination taking into account all palaeontologic and geologic data.

On the hydrogeology of the Lower Tagus Basin and its Cenozoic geologic evolution

The chemical features of the ground water in the Lower Tagus Cenozoic deposits are strongly influenced by lithology, by the velocity and direction of the water movement as well as by the localization of the recharge and discharge zones. The mineralization varies between 80 and 900 mg/l. It is minimal in the recharge zones and in the Pliocene sand and maximum in the Miocene carbonated and along the alluvial valley. Mineralization always reflects the time of permanence, the temperature and the pressure. The natural process of water mineralization is disturbed in agricultural areas because the saline concentration of the infiltration water exceeds that of the infiltrated rainwater. In the discharge zones, the rise of the more mineralized, some times thermal deep waters related to tectonic accidents give rise to anomalies in the distribution of the aquiferous system mineralization model. The diversity of the hydrochemical facies of the ground water may be related to several factors whose identification is some times difficult.

Lithostratigraphy, sequence stratigraphy and depositional setting of the Pliensbachian and Toarcian series in the Lusitanian Basin, Portugal

In the Lusitanian Basin (Central Portugal), the Middle-Upper Liassic series are characterized by an expressive marly limestone accumulation, sediments that were deposited on a homoclinal carbonate ramp. These series belong to the Vale das Fontes, Lemede, S. Gião (and the lateral equivalents Prado and Cabo Carvoeiro Formations) and, partially, to the Póvoa da Lomba Formations. These units, in great part controlled by an accurate ammonite biostratigraphic scale, are organized into two secondorder transgressive-regressive sequences. The first one (SP) is dated of early Pliensbachian/lowermost early Toarcian age; the second (ST) is dated of early Toarcian to early Aalenian.

Calcareous nannofossil assemblages across the Pliensbachian/Toarcian boundary at the Peniche section (Ponta do Trovão, Lusitanian Basin)

The Peniche section has revealed moderately-to-well preserved calcareous nannofossil assemblages across the Pliensbachian/Toarcian boundary. This good record has allowed the proposition of a refined biostratigraphic scheme. The stage boundary, as defined by ammonites, is comprised within the NJ5b C. impontus (NW Europe; BOWN & COOPER, 1998) or the NJT5b L. sigillatus (Mediterranean Tethys; MATTIOLI & ERBA, 1999) nannofossil subzones. Since in the Lusitanian Basin a mixing of N- and S-Tethyan taxa is observed, both biozonation schemes can be applied. Some nannofossil events (mainly first occurrences) are observed earlier in Portugal than in other Tethyan settings. It is still unclear if these events are real first occurrences. A diversification phase occurred across the Pliensbachian/Toarcian boundary. This phase is well recorded at Peniche, where a change is observed passing from the Pliensbachian, when assemblages are dominated by muroliths, to the Toarcian showing assemblages where placoliths are abundant. A quantification of nannofossils per gram of rock shows that absolute abundances are the highest across the Pliensbachian/Toarcian boundary. Indeed, Peniche exhibits nannofossil abundances very high with respect to correlative levels in other Tethyan settings. The pelagic carbonate fraction (produced by nannofossils) is important in the marly hemi-couplets of Peniche. In some levels, nannofossils account for more than 50% of the total carbonate fraction.

On the applicability of joint inversion of gravity and resistivity data to the study of a tectonic sedimentary basin in Northern Portugal

The Chaves basin is a pull-apart tectonic depression implanted on granites, schists, and graywackes, and filled with a sedimentary sequence of variable thickness. It is a rather complex structure, as it includes an intricate network of faults and hydrogeological systems. The topography of the basement of the Chaves basin still remains unclear, as no drill hole has ever intersected the bottom of the sediments, and resistivity surveys suffer from severe equivalence issues resulting from the geological setting. In this work, a joint inversion approach of 1D resistivity and gravity data designed for layered environments is used to combine the consistent spatial distribution of the gravity data with the depth sensitivity of the resistivity data. A comparison between the results from the inversion of each data set individually and the results from the joint inversion show that although the joint inversion has more difficulty adjusting to the observed data, it provides more realistic and geologically meaningful models than the ones calculated by the inversion of each data set individually. This work provides a contribution for a better understanding of the Chaves basin, while using the opportunity to study further both the advantages and difficulties comprising the application of the method of joint inversion of gravity and resistivity data.

Orbital forcing of stratal patterns in an inner platform carbonate sucession: an example from an Upper Hauterivian series of the Lusitanian Basin, Portugal

With an example taken from a late-Hauterivian series of the Lusitanian Basin (Portugal), we will demonstrate the sedimentary record of orbital pattern variations and, consequently, climate variations in an inner platform environment with patterns and isolation changes, allows us to establish 4 major orders of periodicity related to orbital components:- The large cycles ob bed thickness variation, constituted by 31-32 beds, recording the 400 ky eccentricity cycle component;- The medium cycles, represented by byndles of 8-9 beds, related to the 100 ky eccentricity cycle component; - The small cycles, of 3-5 beds, recording the 41 ky obliquity components;- The very small cycles, of 2 beds, related to the 22 ky and 26 ky precession components. The mean duration of each bed is around 11.8 ky, a number very close to that of the precession hemi-cycle. Climatic control on qualitative production is confirmed by the close relation between the bed thickness variations, the insolation variability and the variation of micritized elements concentrations.

The Sinemurian ammonites of the Lusitanian Basin (Portugal): an example of complex endemic evolutioin

Palaeodiversity 3: 59–87; Stuttgart 30 December 2010

An initial examination of the epidemiology of malaria in the State of Roraima, in the Brazilian Amazon Basin

This study firstly describes the epidemiology of malaria in Roraima, Amazon Basin in Brazil, in the years from 1991 to 1993: the predominance of plasmodium species, distribution of the blood slides examined, the malaria risk and seasonality; and secondly investigates whether population growth from 1962 to 1993 was associated with increasing risk of malaria. Frequency of malaria varied significantly by municipality. Marginally more malaria cases were reported during the dry season (from October to April), even after controlling for by year and municipality. Vivax was the predominant type in all municipalities but the ratio of plasmodium types varied between municipalities. No direct association between population growth and increasing risk of malaria from 1962 to 1993 was detected. Malaria in Roraima is of the "frontier" epidemiological type with high epidemic potential.

SEROLOGICAL DETECTION OF HEPATITIS A VIRUS IN FREE-RANGING NEOTROPICAL PRIMATES (Sapajus spp., Alouatta caraya) FROM THE PARANÁ RIVER BASIN, BRAZIL

Nonhuman primates are considered as the natural hosts of Hepatitis A virus (HAV), as well as other pathogens, and can serve as natural sentinels to investigate epizootics and endemic diseases that are of public health importance. During this study, blood samples were collected from 112 Neotropical primates (NTPs) (Sapajus nigritus and S. cay, n = 75; Alouatta caraya, n = 37) trap-captured at the Paraná River basin, Brazil, located between the States of Paraná and Mato Grosso do Sul. Anti-HAV IgG antibodies were detected in 4.5% (5/112) of NTPs, specifically in 6.7% (5/75) of Sapajus spp. and 0% (0/37) of A. caraya. In addition, all samples were negative for the presence of IgM anti-HAV antibodies. These results suggest that free-ranging NTPs were exposed to HAV within the geographical regions evaluated.

Assessing the impacts of land use and land cover change on hydrology of watershed: a case study on Gigel-Abbay Watershed, Lake Tana Basin, Ethiopia

Dissertation submitted in partial fulfillment of the requirements for the Degree of Master of Science in Geospatial Technologies.

Efficacy of sulfadoxine-pyrimethamine and mefloquine for the treatment of uncomplicated Plasmodium falciparum malaria in the Amazon basin of Peru

In vivo antimalarial drug efficacy studies of uncomplicated Plasmodium falciparum malaria at an isolated site in the Amazon basin of Peru bordering Brazil and Colombia showed >50% RII/RIII resistance to sulfadoxine-pyrimethamine but no evidence of resistance to mefloquine.

Low prevalence of hepatitis B virus, hepatitis D virus and hepatitis C virus among patients with human immunodeficiency virus or acquired immunodeficiency syndrome in the Brazilian Amazon basin

Comorbidities in human immunodeficiency virus infection are of great interest due to their association with unfavorable outcomes and failure of antiretroviral therapy. This study evaluated the prevalence of coinfection by human immunodeficiency virus and viral hepatitis in an endemic area for hepatitis B in the Western Amazon basin. Serological markers for hepatitis B virus, hepatitis C virus and hepatitis D virus were tested in a consecutive sample of all patients referred for treatment of human immunodeficiency virus or acquired immunodeficiency syndrome. The variables sex, age, origin and exposure category were obtained from medical records and from the sexually transmitted diseases and acquired immunodeficiency syndrome surveillance database. Among 704 subjects, the prevalence of chronic hepatitis B carriage was 6.4% and past infection 40.2%. The presence of hepatitis B was associated with birth in hyperendemic areas of the Amazon basin, male sex and illegal drug use. The overall prevalence of hepatitis C was 5% and was associated with illegal drug use. The prevalence of hepatitis B and C among human immunodeficiency virus or acquired immunodeficiency syndrome patients in the Western Amazon basin was lower than seen elsewhere and is probably associated with the local epidemiology of these viruses and the degree of overlap of their shared risk factors. An opportunity presents itself to evaluate the prevention of hepatitis C through harm reduction policies and hepatitis B through vaccination programs among human immunodeficiency virus or acquired immunodeficiency syndrome patients.

New focus of active transmission of Chagas disease in indigenous populations in the Peruvian Amazon basin

Introduction Several cases of acute Chagas disease (ACD) have been reported in the Peruvian Amazon basin. Methods The objective was to describe and investigate 6 ACD cases in children from indigenous Amazon communities in the province of Datem del Marañón in Loreto department (2006-2010). Results The mean age was 3.6 years. All patients had fever, 4/6 hepatomegaly, 2/6 splenomegaly, and 5/6 had trypomastigotes of Trypanosoma cruzi on thick smears. The fatality rate was 33.3%. Rhodnius pictipes and Rhodnius robustus adults were found inside the homes and in the peri-domiciles. Conclusions All cases reported were isolated cases. We report a new focus of ACD in indigenous populations.