Bom Jardim Research Articles

Determination of sediment mutagenicity and cytotoxicity in an area subjected to petrochemical contamination

This study is an evaluation of the mutagenic and cytotoxic activity of sediments in Bom Jardim stream, one of the tributaries of the Cai River basin, Rio Grande do Sul, Brazil. This stream receives an indirect contribution of treated effluent from a petrochemical plant. The Salmonella/microsome assay, a microsuspension method, was used to evaluate moderately polar extracts of sediment samples at three points along the stream. The grain size analysis showed a lower mean content of fine particles in the principle face (front) of the complex, and this was also the sampling point with the lowest percentage of extracted organics. Low mutagenic activity was observed at the different sites studied, ranging from 3.3 to 8.3%; cytotoxic activity was more important in this area, ranging from 20 to 40%, adding up the results of assays in the presence and absence of external metabolism. In assays without S9mix there were more frequent mutagenic and cytotoxic responses, with frameshift mutations being the most frequent. The results also showed that there was a gradual, seasonal distribution of the responses as the stream mouth is reached, the most compromised points being in front of and downstream of the complex. Mutagenic and cytotoxic activity in sediment samples has proved important to determine environmental quality, despite the complexity of the chemical composition of the environmental matrix. Furthermore, use of the Salmonella assay to monitor mutagenesis and cytotoxicity helped identify the presence of pollutants. This assay is an important tool, aimed mainly at actions to preserve the genetic heritage of the fauna and flora affected by human activity and to improve environmental quality.

A Polyethylenetherephthalate (PET) device for sampling freshwater benthic macroinvertebrates

A new device to sample freshwater benthic macroinvertebrates was used in a low and sandy stretch of a Brazilian sub-tropical river (the River Cai, Triunfo, RS) and in one of its small tributaries, Bom Jardim brook (Arroio Bom Jardim). In this study, the effectiveness of this device, a PET sampler, was tested at different sites in the river and the brook throughout the four seasons between 2001-2002. Comparisons were made by PCA and ANOVA, both employing a bootstrap procedure based on similarity matrices. The PET sampler proved to be a reliable tool for detection of seasonal and spatial differences in richness, total abundance of organisms, and Shannon's diversity index in both river and brook and is therefore recommended for use in the monitoring of macroinvertebrate communities in this system.

Redefinição do Grupo Bom Jardim (Neoproterozóico Iii) em sua área-tipo: litoestratigrafia, evolução paleoambiental e contexto tectônico

The Camaqua Group is composed of sedimentary and volcanogenic successions that crop out in the south-central portion of the Rio Grande do Sul State (southern Brazil). This supergroup is partially covered by Parana Basin units and has been divided into sub-basins by the uplift of basement highs. This post-depositional tectonic segmentation, and the lithologic similarity among sedimentary successions of different stratigraphic levels makes it difficult to establish a formal lithostratigraphic column of the Bom Jardim Group without detailed field work. This paper presents a review of the lithostratigraphy of the Bom Jardim Work in its type-area, constituted by siliclastic, volcanic (basalts, andesites and rhyolites) and volcaniclastic rocks grouped in three units, with transitional contacts among each other. Cerro da Angelica Formation: rhythmic intercalation of sandstones, siltstones and claystones, as well as pebbly sandstones and minor volcaniclastic rocks (peperites), formed in sub-lacustrine fans and overlying deltaic systems. Hilario Formation: volcanic rocks of basic, intermediate and acid composition (basalts, latite-basalts, latites, andesites and rhyolites) placed in subaquatic environments, and minor pyroclastic rocks (lapilli-tuffs and coarse-grained lithic and vitric tuffs) placed by gravity flows or settled in water. Picada das Gracas Formation: rhythmic layers of fine-grained sandstones, siltstones and claystones formed in pro-delta environments, overlain by a thick succession of conglomerates and pebbly sandstones of proximal fan-deltas. Fluvial and fluvial-dominated deposits occur at the top of the unit.

Proposta litoestratigráfica e considerações paleoambientais sobre o Grupo Maricá (Neoproterozóico Iii), Bacia Do Camaquã, Rio Grande Do Sul

The Marica Group (Rio Grande do Sul State, Southern Brazil) contains the first sedimentary successions deposited after the denudation and tectonic subsidence of the basement units of the Gaucho Shield that was formed during the Brasiliano Orogeny. This subsidence event lead to the generation of the Camaqua Basin (Neoproterozoic III / Early Paleozoic), which posteriorly evolved to a rift system characterized by volcanosedimentary successions (Bom Jardim group) and coarse-grained siliciclastics (Santa Barbara and Guaritas groups). The Marica group consists of 2000-2500 m of arkosean sandstones and, in smaller proportion, conglomerates and pelites. Three lithostratigraphic units are here defined: Passo da Promessa formation (fluvial sandstones and conglomerates), Sao Rafael formation (marine sandstones and rhythmites) and Arroio America formation (fluvial sandstones and conglomerates). Stratigraphic and provenance analyses of the alluvial units, as well as paleocurrent data, show that: (i) sedimentary transport was towards the North during the evolution of these units; (ii) source areas were composed of granitic rocks, both foliated and unfoliated; (iii) there was an important contribution of a volcanic source, comprehending mainly rhyolitic and pyroclastic rocks, which frequency of occurrence increase towards the top of the succession, also including rare andesites in the Arroio America formation. The stratigraphic relationship among the Marica formation and the basement units shows that the basin was not related to the Brasiliano Orogeny, as revealed by the fact that the Marica group overlies both the cratonic foreland regions and the collisional suture, represented respectively by paleoproterozoic granulites (Rio the La Plata Craton) and a neoproterozoic subduction complex (Rio Vacacai Terrane).

OS SOLOS DA BACIA DO RIBEIRÃO BOM JARDIM E SUAS RELAÇÕES COM RELEVO E OS RECURSOS HÍDRICOS, UBERLÂNDIA (MG)

The present work describes the methodology used to map the soils in the Basin of the Bom Jardim Creek (in the scale of 1:50,000) as well as the relations among the soils, relief and the hydric resources. The Bom Jardim creek is the main affluent to the Uberabinha river on its left margin. It drains an area of 396.54 km2 of lands located in the municipalities of both Uberaba and Uberlândia. The soils in the basin of the Bom Jardim creek are latosoils in the most, with medium texture, dystrophic, with low levels of organic substances. Around 20% of the basin have soils affected by hydromorphism (Neosoils, Gleisoils and Organosoils). These are found in the lane and meadow areas where the resurgence of the water table occurs. Such soils play a vital role in the hydrologic balance of the courses in the basin of the Bom Jardim creek.

Volcanic cycles and setting in the Neoproterozoic III to Ordovician Camaquã Basin succession in southern Brazil: characteristics of post-collisional magmatism

The Camaquã Basin comprises a volcano-sedimentary succession, located in southernmost Brazil, and represents a molasse basin formed at the post-collisional stage of the Brasiliano/Pan-African orogenic cycle in the Neoproterozoic III to Ordovician period. This basin is one of the most well-preserved ancient volcano-sedimentary sequences undeformed and unmetamorphic in the world, dominantly developed on a continental setting under subaerial conditions. It is composed of five major stratigraphic units, four of them with a distinct volcanic character from the bottom to the top, as: (1) Maricá; (2) Bom Jardim; (3) Acampamento Velho; (4) Santa Bárbara; and (5) Guaritas Allogroups. A concise sight of geochemical and isotopic rock data is presented, as well as stratigraphic correlation and description of rock structures and textures that lead to the identification of their genetic processes, the aim of this paper, indicating a relation with a coeval plutonism, and volcanism that evolved from high-K calc-alkaline to shoshonitic and ended with a silica-saturated sodic alkaline magmatism, with a crustal component represented by peraluminous granites. Volcanic deposits from bottom to top are made mostly of volcanogenic sedimentary deposits, succeeded by basic to intermediate lava and pyroclastic flows of shoshonitic affinity, followed by intermediate and acid lava flows and ignimbrites of sodic alkaline affinity. The last volcanic event is represented by basalt pahoehoe flows, probably of mildly alkaline sodic affinity.

The link between hydrothermal epigenetic copper mineralization and the Caçapava Granite of the Brasiliano Cycle in southern Brazil

Base-metal deposits in the Caçapava do Sul Copper Province are hosted by both volcanosedimentary rocks of the Bom Jardim Group and by metamorphic rocks of the Passo Feio Formation, and show a spatial relationship to the Caçapava Granite. These associations have led to much controversy about the genesis of the base-metal deposits, which has been at least partly resolved by precise dating using SHRIMP (Sensitive High Resolution Ion Microprobe) U/Pb zircon studies combined with S, Pb, and Sr isotope trace studies. The Passo Feio Formation is Neoproterozoic in age and was derived from a complex continental source, as shown by the presence of xenocryst zircons of Archaean, Paleoproterozoic, and Neoproterozoic ages. It was metamorphosed at ca. 700 Ma. The syntectonic Caçapava Granite that intruded the supracrustal rocks of the Passo Feio Formation at 562 Ma was derived from an old sialic basement. Lead-isotope data are consistent with a 562 Ma age for the base-metal sulphide deposits sited in the Passo Feio Formation. The least-radiogenic compositions lie between the field of the isotopic compositions of the Caçapava Granite and rocks of the Passo Feio Formation, suggesting that Pb in the sulphide deposits may have been derived from both sources. The Pb, like that in the Caçapava Granite and Passo Feio Formation, was derived from a primitive crustal source. Sulphur isotope data from the base-metal sulphide deposits in the Passo Feio Formation are compatible with a mixed sedimentary and magmatic source. The most logical model for ore genesis, based on the isotopic data and spatial relationships, is that magmatic metal-bearing fluids from Caçapava Granite leached metals from the Passo Feio Formation and that the deposited sulphides therefore show mixed isotopic signatures. However, there is also some isotopic evidence from the Caçapava Granite itself that suggests assimilation of S-bearing rocks of the Passo Feio Formation during emplacement. Thus, isotopic signatures could have been inherited from assimilated metal sulphides at this stage, and deposition could have been entirely from Caçapava Granite-derived magmatic fluids. Importantly, the inferred 562±8 Ma age for the deposits in the Passo Feio Formation is younger than the well-constrained age of 594±5 Ma for the Camaquã/Santa Maria deposits. Thus, the epigenetic sulphides in the Passo Feio Formation cannot be the source of these deposits as previously suggested. Other isotopic data also argue against such a model.

Prevalência de anticorpos anti-Babesia equi em eqüinos no Planalto Catarinense

Para avaliar a prevalência de anticorpos anti- Babesia equi, através da técnica de imunofluorescência indireta (IFI), foram examinados 397 amostras de soro. As amostras de sangue, para obtenção dos soros, foram coletadas de eqüinos de diferentes idades, raças, sexos, nascidos e criados no Planalto Catarinense, dos municípios de Lages, São Joaquim, Bom Jardim da Serra, Campos Novos, Anita Garibaldi, Curitibanos e Correia Pinto. Os resultados obtidos indicaram a existência de 50,38% de animais sorologicamente reativos para B. equi, na diluição de 1:40. Entre os municípios, os percentuais de animais soropositivos variaram de 18,51% a 64,70%.

Nd and Sr-Isotopic and U-Pb Geochronologic Constraints for Evolution of the Shoshonitic Brasiliano Bom Jardim and Toritama Complexes: Evidence for a Transamazonian Enriched Mantle Under Borborema Tectonic Province, Brazil

The Bom Jardim and Toritama complexes form elongated bodies between the Pernambuco-Alagoas massif and Pajeú-Paraíba fold belt and comprise multiphase intrusions of monzonitic and syenitic compositions. Low-angle foliation recorded in both complexes, indicated by alignment of euhedral minerals, runs parallel to the main thrust faults within the region. This suggests that emplacement of the complexes could be related to the thrust faults. The whole-rock geochemistry of major and trace elements, and the associated mineral chemistry, have established a shoshonitic affinity for these complexes. The mineral chemistry of the essential minerals within both complexes, the presence of magnetite, and the constant Fe/Fe + Mg ratios in biotites and amphiboles with increasing differentiation indicate trends compatible with a fractionating magma under high f(O2) conditions. The general overlap and similarities in mineral chemistry between the mafic minor facies and the less-evolved members of the major facies indicate that they share the same source. Major and trace-element chemistry coupled with mineral chemistry indicates that the main geochemical trends determined for the complexes are the result of fractional crystallization, with the removal of amphibole plus biotite and plagioclase in the early stage, followed by the removal of K-feldspar within the developing magmas. The 592 ± 7.2 Ma U/Pb zircon age recorded in both complexes is associated with low-angle foliation and suggests that they probably represent magmatism associated with the end of a Neoproterozoic compressive regime within the Pajeu-Paraiba fold belt. The Bom Jardim and Toritama rocks have high LILE/HFSE ratios; high MgO, Cr, and Ni contents; and lower 87Sr/86Sr ratios compared to crustal granitoids. However, the complexes also have a value of ϵNd (−20 at 0.6 Ma) similar to those recorded in 2.0 Ga (U/Pb in zircon) migmatites from the Pajeu-Paraiba fold belt. Thus, the source of these rocks probably is the result of partial melting of a metasomatized Transamazonian (2.0 Ga) mantle, which occurred during the end of the Brasiliano compressive regime.

PARAGÊNESE E SUCESSÃO MINERAL NAS DIFERENTES ETAPAS DA EVOLUÇÃO DA MINERALIZAÇÃO Cu-Pb-Zn DO DISTRITO DE CAMAQUÃ, RS

The sulfide mineralization of die Camaqua Mines (Cu) and of the Santa Maria Deposit (Pb-Zn). State of Rio Grande do Sul, southern Brazil, is associated with red bed conglomerates and sandstones, deposited hi an alluvial fan environment at the end of the Brasiliano Event. The non opaque cement and ore mineral analysis allow to identify four main phases hi the mineralization process occurred after the sedimentation: the eodiagenetic and mesogenetic phases are represented by the formation of hematite I-rutile and pyrite I-marcasite, respectively; the late diagenetic to epigenetic phase has occurred at deep burial levels and it was superimposed to the least non opaque cements. It comprises the galena-sphalerite-chalcopyrite paragenesis in the Santa Maria Deposit and the pyrite Il-chalcocite I-bornite I-chalcopyrite paragenetic sucession in the Camaqua Mines; the paleo-oxidation/cementation phase took place after uplift and unroofing. It is well observed in the Camaqua Mines where the previous sulfide phases were altered and replaced by die hematite IT-bomite Il-chalcocite TI-covellite. In the Santa Maria Deposit occur the hematite n-stephanite-chalcocite II-covellite-native silver paragenesis; and the tectonic remobilization phase of the previous ore cements has occurred during bed tilting and leaded to the formation of pvrite-bomite-chalcopyrite-quartz and hematite-bornite-chalcocite-barite-calcite veins in the Camaqua Mines, and only of veinlets with galena-sphalerite in die Santa Maria Deposit. The deposition of die Guaritas Formation occurred when die mineralization process had finished, i.e. after the tilting of die Bom Jardim Group beds.

More on anti-HIV antibodies in Brazilian Indians

There have been reports of the detection of antibodies to HIV (human immunodeficiency virus) in sera of Indians living primitively in the Amazon region of French Guiana (De-The et al. 1985) and Venezuela (Rodriguez et al. 1985). These findings have led some investigators to screen sera of Brazilian Indians for anti-HIV antibodies (Galvao-Castro & Pereira 1986; Serpa et al. 1986). Here we report the results of a survey carried out on 307 sera of Amerindians living deep in the Amazonian jungle in the southeast region of Para state between the rivers Xingu and Tocantins in conditions of isolation very similar to those of the tribes screened in Venezuela and French Guiana. We studied 121 sera of the tribe Xikrin do Catete (42.4% of the population) 69 sera of the tribe Xikrin do Bacaja (39.2% of the population) 71 sera of the tribe Paracana do Bom Jardim (52.9% of the population) and 46 sera of the tribe Paracana do Marudjewara (58.9% of the population). All sera were collected from adults. All 307 samples were collected in 1985 and screened for anti-HIV antibodies in 1986 by enzyme-linked immunosorbent assay (Organon and Electro-Nucleonics). All were negative except for 10 sera which showed low reactivity (between 1.1 and 3.5 times the cutoff). Nevertheless when tested by the Western blot technique (Biotech Research) all were negative. These results are consistent with those reported by other authors who also failed to find anti-HIV antibodies in other Brazilian tribes. These surveys indicate that anti-HIV seropositivity is not generally common among Brazilian Indians living in the Amazon region. However further surveys should be made near the borders between Brazil and Guiana or Venezuela. (full text)

Palaeomagnetism of the Itajai, Castro and Bom Jardim groups from southern Brazil

SUMMARY Palaeomagnetic results corresponding to geological units associated with the Brasiliano (Pan-African) cycle (Late Pre-Cambrian - Early Palaeozoic), are presented. A total of 160 hand samples from the Itajai, Castro and Bom Jardim Groups from southern Brazil were submitted to laboratory treatment. 46 acid volcanic samples from the Campo Alegre Formation (Itajai Group) yielded two magnetic components labelled A1 (Dm= 36d, Im= -40d, A95= 10d) and A2 (Dm= 44d, Im= -8d, A95= 4d) with respective palaeomagnetic poles CA (223dE, 57dS, A95= 9d) and SV (200dE, 43dS). 20 acid volcanic samples from the Castro Group yielded a single stable direction of magnetization (Dm= 347d, Im= -52d, A95= 12d) with palaeopole CT (4dE, 76dS, A95= 15d). 12 acid samples from the Acampamento Velho Formation (Bom Jardim Group) yielded two magnetic components labelled B1 (Dm= 156d, Im= 69d, A95= 17d) and B2 (Dm= 207d, Im= -15d, A95= 42d) with respective palaeopoles AV1 (338dE, 61dS, A95= 28d) and AV2 (345dE, 44dN A95= 37d). Seven sedimentary samples from the Vargas Formation (Bom Jardim Group) yielded a magnetic component (Dm= 110d, Im= 81d, A95= 17d) with palaeopole VA (322dE, 34dS, A95= 30d). Finally, 11 andesitic volcanic samples yielded a magnetic component (Dm= 108d, Im= -4d, A95= 12d) with palaeopole Hi (228dE, 14dN, A95= 9d). These results are compared with APWP's constructed for the Gondwana Continents.