Seed dispersal by fishes in tropical and temperate fresh waters: The growing evidence

Fruit-eating by fishes represents an ancient (perhaps Paleozoic) interaction increasingly regarded as important for seed dispersal (ichthyochory) in tropical and temperate ecosystems. Most of the more than 275 known frugivorous species belong to the mainly Neotropical Characiformes (pacus, piranhas) and Siluriformes (catfishes), but cypriniforms (carps, minnows) are more important in the Holarctic and Indomalayan regions. Frugivores are among the most abundant fishes in Neotropical floodplains where they eat the fruits of a wide variety of trees and shrubs. By consuming fruits, fishes gain access to rich sources of carbohydrates, lipids and proteins and act as either seed predators or seed dispersers. With their often high mobility, large size, and great longevity, fruit-eating fishes can play important roles as seed dispersers and exert strong influences on local plant-recruitment dynamics and regional biodiversity. Recent feeding experiments focused on seed traits after gut passage support the idea that fishes are major seed dispersers in floodplain and riparian forests. Overfishing, damming, deforestation and logging potentially diminish ichthyochory and require immediate attention to ameliorate their effects. Much exciting work remains in terms of fish and plant adaptations to ichthyochory, dispersal regimes involving fishes in different ecosystems, and increased use of nondestructive methods such as stomach lavage, stable isotopes, genetic analyses and radio transmitters to determine fish diets and movements. (C) 2011 Elsevier Masson SAS. All rights reserved.

Leaiid conchostracans from the uppermost Permian strata of the Parana Basin, Brazil: Chronostratigraphic and paleobiogeographic implications

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

A new Pennsylvanian Oriocrassatellinae from Brazil and the distribution of the genus Oriocrassatella in space and time

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

A stratigraphic chart of the Late Carboniferous/Permian succession of the eastern border of the Parana Basin, Brazil, South America

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Paraná Basin: Mineral resource potentials in Brazil, Uruguay, and Paraguay

The Paraná Basin is a Western Gondwanan cratonic basin that is better defined as the Paraná depositional site, since it has a diverse history as a basin. Sedimentation started in the Ordovician-Silurian, followed by extensive marine Devonian deposition. A Late Paleozoic/ Triassic facies cycle wedge was clearly built during Pangean time. The Early Cretaceous was characterized by extensive basaltic lava flows immediately before the break-up of Pangea. Following these rifting and drifting processes, the basin's structural framework was totally rebuilt, generating new depositional sites in the Late Cretaceous to Tertiary. Based on more recent data, at least two different basins may be defined during the evolution of what was once considered a unique basin. Nevertheless, even if considered as a single basin, the sedimentary pile of the Paraná Basin has considerable economic potential, until now exploited only rudimentarily, except for its groundwater resources. Aggregates, limestones, clays, industrial sands, gems, dimension stones, hydrocarbons, coal, peat, and uranium are some of the potential mineral resources of this basin. Copyright © 1997 by V. H. Winston & Son, Inc. All rights reserved.

Seqüência Ordovício-Siluriana e Devoniana no Flanco Norte da Bacia do Paraná

Two stratigraphic sequences characterize the basal units of the Paraná basin. The Ordovician-Silurian sequence overlie directly the Neoproterozoic basement and consists of a 55m-thick unit of coarse-grained sandstones, diamictites, fossiliferous shales and fine-grained micaceous sandstones. The Alto Garças Formation constitutes the base of the sequence and is made of coarse-grained, massive and reddish sandstones associated with conglomeratic lenses. Diamictites with pebbles of diverse composition in siltic and arenaceous matrix were deposited during the Ordovician-Silurian glaciation. Whenever the basal sandstones are absent, the diamictites directly overlie the basement. The diamictites were previously included in the Vila Maria Formation. However our study revealed that they are part of the Iapó Formation. A transgressive event following the glaciation is marked by the deposition of the Vila Maria Formation, which is characterized by fossiliferous (mollusks, brachiopods, cryptospores and microplankton) and laminated shales and siltstones, grading upward to fine-grained micaceous sandstones with hummocky cross stratification. Layers containing trace fossils (Anthrophycus) occur at the transition between the siltstones and the sandstones. The Devonian sequence is represented by 80-170 meters thick sandstones of the Furnas Formation (lower unit) and a sucession of sandstones, siltstones and shales of the Ponta Grossa Formation (upper unit). Unlike other areas of the Paraná Basin, the Ponta Grossa Formation is characterized by coarsening-upward succession beginning with fine sandstones and grading upward to coarse and very-coarse sandstone beds. Cretaceous modifying tectonics affected the Paleozoic sequences, which are cut by a series of faults, in some cases showing displacements greater than 500 meters.

Nova contribuiçao ao conhecimento da formação Rio Claro (T) na Folha Rio Claro (SP)

The Rio Claro Formation mainly occurs in the county of Rio Claro (SP) lying unconformably on Paleozoic and Mesozoic rocks. Its thickness is 30-40 m. It shows fine to coarse, regular to poor sorted, Triable sandstones and conglomerates with quartzite and quartz clasts in the base. Thin layers of mudstone occur interbeded. Stratigraphic maps had been elaborated in recent analyses allowing to improve the knowledge about the formation. The biggest thicknesses occur on the east part of the studied area. The coarse/fine clastic ratio map demonstrates that fine sediments are concentrated in the east side, and suggests the existence of barriers which conditioned perennial water body (or bodies) where decantation took place (east, south and southeast sides). The structural contour map of the Rio Claro Formation base indicates a NW/SE trough which was the main depositional axis. The integrated analysis demonstrates that the formation is formed by lacustrine, fluvial and debris flows deposits whose source area was located on NW side, with coalescent alluvial fans from where braided to psamitic meandering fluvial channels came. The location of the source area suggests no link with the Corumbataf River paleo-terraces.

Influência do arcabouço hidroestratigráfico nas ocorrências de arsênio em águas subterrâneas ao longo do corredor termal do rio Uruguai (Argentina - Brasil - Uruguai)

The Thermal Corridor of Uruguay River is located in the triple border of Argentine, Brazil and Uruguay, and shows an intense economic thermal tourism activity, mainly based on groundwaters from Guarani Aquifer System (GAS). Recent studies have pointed out the occurrence of high concentrations of arsenic (>10 μg/L) in GAS groundwater in this area. The complex geological and hydrogeological framework in the area is associated to the Paraná Basin geological evolution south of the Assuncion-Rio Grande Arch; it encompass paleozoic marine sequences and continental sequences permian/eotriassic to mesozoic in age, which are covered by basaltic lavas of Serra Geral Formation. Iron oxide coatings have been described in sandstones of Buena Vista and Sanga do Cabral formations, which underlie GAS units. Arsenic occurrence is associated to sodium bicarbonate groundwater with pH values over 8.0. Arsenic is released to groundwater by desorption from iron oxides/hydroxides, as result of the higher pH of these waters, indicating that arsenic is released from the units that underlie GAS units. Increase in chromium and uranium concentrations are also related to high pH groundwaters, thus indicating special care on using groundwater from this region.

Lower Permian stems as fluvial paleocurrent indicators of the Parnaíba Basin, northern Brazil

A comprehensive biostratinomic study was carried out with abundant stems from the Lower Permian Motuca Formation of the intracratonic Parnaíba Basin, central-north Brazil. The fossils represent a rare tropical to subtropical paleofloristic record in north Gondwana. Tree ferns dominate the assemblages (mainly Tietea, secondarily Psaronius), followed by gymnosperms, sphenophytes, other ferns and rare lycophytes. They are silica-permineralized, commonly reach 4 m length (exceptionally more than 10 m), lie loosely on the ground or are embedded in the original sandstone or siltstone matrix, and attract particular attention because of their frequent parallel attitudes. Many tree fern stems present the original straight cylindrical to slightly conical forms, other are somewhat flattened, and the gymnosperm stems are usually more irregular. Measurements of stem orientations and dimensions were made in three sites approximately aligned in a W-E direction in a distance of 27.3 km at the conservation unit Tocantins Fossil Trees Natural Monument In the eastern site, rose diagrams for 54 stems indicate a relatively narrow azimuthal range to SE. These stems commonly present attached basal bulbous root mantles and thin cylindrical sandstone envelopes, which sometimes hold, almost adjacent to the lateral stem surface, permineralized fern pinnae and other small plant fragments. In the more central site, 82 measured stems are preferentially oriented in the SW-NE direction, the proportion of gymnosperms is higher and cross-stratification sets of sandstones indicate paleocurrents mainly to NE and secondarily to SE. In the western site, most of the 42 measured stems lie in E-W positions. The predominantly sandy succession, where the fossil stems are best represented, evidences a braided fluvial system under semiarid conditions. The low plant diversity, some xeromorphic features and the supposedly almost syndepositional silica impregnation of the plants are coherent with marked dry seasons. Thick mudstones and some coquinites below and above the sandy interval may represent lacustrine facies formed in probably more humid conditions. The taphonomic history of the preserved plants began with exceptional storms that caused fast-flowing high water in channels and far into the floodplains. In the eastern site region, many tree ferns only fell, thus sometimes covering and protecting plant litter and leaves from further fragmentation. Assemblages of the central and western sites suggest that the trees were uprooted and transported in suspension (floating) parallel to the flow. Heavier ends of stems (according to their form or because of attached basal bulbous root mantle or large apical fronds) were oriented to upstream because of inertial forces. During falling water stage, the stems were stranded on riverbanks, usually maintaining the previous transport orientation, and were slightly buried. The perpendicular or oblique positions of some stems may have been caused by interference with other stems or shallow bars. Rare observed stems were apparently waterlogged before the final depositional process and transported as bedload. The differences of interpreted channel orientations between the three sites are expected in a braided fluvial system, considering the very low gradients of the basin and the work scale in the order of tens of kilometers. The mean direction of the drainage probably was to east and the flows apparently became weaker downstream. This study seems to provide reliable data for paleocurrent interpretations, especially considering areas with scarce preserved sedimentary structures. © 2013 Elsevier Ltd.

Sr-Nd-Pb isotopic constraints on the nature of the mantle sources involved in the genesis of the high-Ti tholeiites from northern Paraná Continental Flood Basalts (Brazil)

There has been little research on geochemistry and isotopic compositions in tholeiites of the Northern region from the Paraná Continental Flood Basalts (PCFB), one of the largest continental provinces of the world. In order to examine the mantle sources involved in the high-Ti (Pitanga and Paranapanema) basalt genesis, we studied Sr, Nd, and Pb isotopic systematics, and major, minor and incompatible trace element abundances. The REE patterns of the investigated samples (Pitanga and Paranapanema magma type) are similar (parallel to) to those of Island Arc Basalts' REE patterns. The high-Ti basalts investigated in this study have initial (133Ma) 87Sr/86Sr ratios of 0.70538-0.70642, 143Nd/144Nd of 0.51233-0.51218, 206Pb/204Pb of 17.74-18.25, 207Pb/204Pb of 15.51-15.57, and 208Pb/204Pb of 38.18-38.45. These isotopic compositions do not display any correlation with Nb/Th, Nb/La or P2O5/K2O ratios, which also reflect that these rocks were not significantly affected by low-pressure crustal contamination. The incompatible trace element ratios and Sr-Nd-Pb isotopic compositions of the PCFB tholeiites are different to those found in Tristan da Cunha ocean island rocks, showing that this plume did not play a substantial role in the PCFB genesis. This interpretation is corroborated by previously published osmium isotopic data (initial γOs values range from+1.0 to+2.0 for high-Ti basalts), which also preclude basalt generation by melting of ancient subcontinental lithospheric mantle. The geochemical composition of the northern PCFB may be explained through the involvement of fluids and/or small volume melts related to metasomatic processes. In this context, we propose that the source of these magmas is a mixture of sublithospheric peridotite veined and/or interlayered with mafic components (e.g., pyroxenites or eclogites). The sublithospheric mantle (dominating the osmium isotopic compositions) was very probably enriched by fluids and/or magmas related to the Neoproterozoic subduction processes. This sublithospheric mantle region may have been frozen and coupled to the base of the Parana basin lithospheric plate above which the Paleozoic subsidence and subsequent Early Cretaceous magmatism occurred. © 2013 Elsevier Ltd.

Contribuições da geologia para o desenvolvimento sustentável do turismo no município da Estância Turística de Paraguaçu Paulista (SP)

Pós-graduação em Geociências e Meio Ambiente - IGCE

Tafonomia das rochas carbonáticas conchíferas das formações Teresina e Rio do Rasto (Permiano, Bacia do Paraná)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Vertebrados fósseis do estado de Goiás, com ênfase em sua fauna de amniotas, compreendida entre o período permiano e a época pleistoceno

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Litoestratigrafia da bacia do Araripe: reavaliação e propostas para revisão

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Difusão de conhecimentos geocientíficos por meio de web-mapping: ensaio de aplicação temática com geoturismo em uma região da borda leste da bacia do Paraná

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)