Serviço Social e Política: uma análise da participação dos assistentes sociais no Conselho Regional de Serviço Social 14ª região

This paper analyzes the political participation of Social Workers at the Social Service Regional Council Region 14th. The theoretical and methodological framework of this investigation has as its perspective the totality of social life and its determining relations within the object of study. To the production, analysis and collecting of data it was used a qualitative approach considering a bibliographical and documental research as well as a series of twelve interviews with 2005-2008 and 2008-2011 managing counselors of CRESS/RN. It was also used the data obtained from other special interviews held with the social workers in the period between 2007 and 2008. The results of this study allow and affirm the political dimension of Caseworkers and the CRESS/RN as a space of political activity with opportunities for effective and collective elaboration of strategies in order to reach the fulfillment of the ethical and professional policy of the Social Work. From a historical viewpoint, the beginning of this process is marked by the struggle for democracy, the end of military dictatorship, the establishment of the State of Human Rights. The Democratization of the so called Federal Council of Social Workers and its Regional Councils of Social Workers, CFAS / CRAS, respectively, area a result of the participation of the category in an effort to fight for democratization in Brazil. The objective of this research, so, is to understand which the socio-historical determinants are, that focus objectively and subjectively in the demobilization of social workers in CRESS Region 14th - in the contemporary and historical context. Among the results obtained we identified the ignorance of some professional workers and also of some advisors, regarding the existence and the role of the Council, as well as the commercialization of Education that compromises the quality of the professional training in its theoretical and methodological, ethical and political dimensions. According to our understanding, this shows a the presence of a non-critical professional profile based on a false reality, on the precariousness of employment contracts which undermine the political organization and submit the worker to various social exploring mechanisms such as double shift and ultimately the fragility of the management of the Regional Council -, as a consequence of the offensive capitalist system that ideologically invests to stop the political organization founded in a critical and democratic perspective. The low participation of some advisors and, in general, the category in CRESS / RN, despite its objective conditions, is a reality and it is presented to us as a challenge to future managements and policy consolidation to society. Inasmuch as the category intends to guarantee the high quality of its social workers, the demands of future counselors, their skills and abilities in dealing with regulatory issues, administrative policies that pervade the everyday life of CRESS / RN are necessary

Instrumentalidade do serviço social na previdência social no Brasil contemporâneo

In the sociability of the capital, the challenges to the consolidation of social security as a public policy become expressive, which has implications for social security services, particularly for Social Works who works for the security and fulfillment of social rights. Therefore, in this context of denial of these rights becomes relevant the work of social worker, as a professional committed to the ethical-political project and the Matrix Theory and Methodology of Social work, which potentiate the action able to establish professional articulated strategies for the strengthening of collective struggles for equality in society. Thus, this study examines the instrumentality of social work in the contemporary world and its contribution to the realization of rights. For this, we conducted a literature review, using authors dealing with the issue, as Behring (2008), Boschetti (2003), Mota (1995), Guerra (2007) among others, as well as documentary research through laws, decrees, instructions Normative, Internal Guidelines, and especially the analysis of the Matrix itself of Social Work in welfare. We use also of paramount importance to our analysis - the field research, using techniques such as semi-structured interview and questionnaire. The research enables the identification of important aspects of the subject studied, as the understanding of professionals about the instrumentality of Social Works in its ethical-political aspects, both theoretical and methodological and technicaloperative. The demands made by the managers for the profession on the sociooccupational have extrapolated the powers and duties of the Law Regulating the Profession and the Matrix of Social Work in welfare. The subjects of this study emphasize the role of social category of the National Institute of Social Security and the Federal Council of Social Service in defense of Social Works. The knowledge of social and institutional framework is critical to building control strategies that strengthen social security and public policy, the guarantor of social rights for workers in Brazil

Conservação dos invertebrados em área de proteção ambiental litorânea no nordeste do Brasil: contribuições da educação ambiental para a sustentabilidade

Today's society is in a real collapse of an environmental nature. The populations are lost due to a dream of development without thinking of the consequences that said development can bring to human populations. Thus, it is necessary that strategies be developed for the purpose of protecting the flora and fauna that is at risk from suffering the pressure to achieve this development. Thus important issues involving the need to conserve nature and the creation of protected areas as these strategies are increasingly being developed in research, whether in the biological and / or social. In this sense, the aim of this research through environmental perception social actors for the formation of significant elements for understanding the relationship between man and nature, and from there to provide actions for sensitization. As well as changing attitudes towards environmental issues, to thereby provide analysis based on Environmental Education in order to provide the production of environmental knowledge as a tool that provides value shift. This area of research was to study the Environmental Protection Area Jenipabu - APA Jenipabu, located in northeastern Brazil. Where, from the environmental perception of students from schools within and around this Nature Conservation Unit notes were made regarding the value and meaning given by students, and how this, the feeling of belonging to these groups. This dissertation is composed of two chapters, the first is titled Environmental perception and feeling of belonging in the area of environmental protection in coastal RN - Brazil, where it makes a diagnosis of how these groups understands and realizes the Unity of Nature Conservation. The second, which is titled Construction of environmental knowledge and conservation of invertebrates in the Environmental Protection Area in the northeast coast of Brazil, specifically developed in the school from within the APA Jenipabu, in order to promote a sense of belonging for those students who become multipliers, in order to realize the importance and necessity of having this unit for Nature Conservation. Looking to the degree of importance of environmental education as a tool to raise awareness on conservation of invertebrates and is all the fauna and flora exists, whether in a conservation of nature or not

Reformas administrativas no Brasil: o caso do governo do estado do Piauí

From the 1980s, with technological development, globalization, and in a context of increasingly urgent demands, there is an international movement to modernize the state structures. Being driven by the victory of conservative governments in Britain and the U.S., this speech reform comes only to Brazil in the 1990s, the government of Fernando Henrique Cardoso. Thus, in view of the recent movement of states to implement this reform agenda in their structures this research was to identify the elements that made it possible to attempt to modernize the administrative structure of the state of Piauí in 2003, in view of the political and administrative career in which the state was entered. Seeking to clarify the problem studied here, through a case study carried out a descriptive and exploratory, using a technique of gathering data to document research and interviews semi-structured. As the lens of analysis for this study used the neo-historical and sociological institutionalism, through which it sought to identify the critical moment in which they gave the Administrative Reform of Piaui, the process of breaking with the political and administrative career that previously had being followed, and the isomorphic mechanisms that enabled this speech reform comes up to this state, mechanisms that allow the homogenization of the organizational field. In general it appears that the search for new patterns and new technologies for management by the states in Brazil is due to the context of fiscal crisis in which the states were entered, forcing them to seek alternative models of management . The process of diffusion of New Public Management agenda for the states became possible, among other factors, due to the new scenario in which was inserted into the Brazilian federal system in the second half of the 1990s, characterized by a greater articulation between the horizontalstates, where through the mechanisms of isomorphic institutional change was made possible by the absorption of the speech states reformer of the 1990s. However, due to the specificities of each region is given the experiences state unevenly. In the case of Piauí Administrative Reform only became possible due to the rearrangement of political forces in the state and the mechanisms of isomorphic institutional change, which allowed, in 2003, the state government to absorb the speech reformer

Arcabouço geofísico, isostasia e causas do magmatismo cenozóico da província Borborema e de sua margem continental (Nordeste do Brasil)

The Borborema Province (BP) is a geologic domain located in Northeastern Brazil. The BP is limited at the south by the São Francisco craton, at the west by the Parnaíba basin, and both at the north and east by coastal sedimentary basins. Nonetheless the BP surface geology is well known, several key aspects of its evolution are still open, notably: i)its tectonic compartmentalization established after the Brasiliano orogenesis, ii) the architecture of its cretaceous continental margin, iii) the elastic properties of its lithosphere, and iv) the causes of magmatism and uplifting which occurred in the Cenozoic. In this thesis, a regional coverage of geophysical data (elevation, gravity, magnetic, geoid height, and surface wave global tomography) were integrated with surface geologic information aiming to attain a better understanding of the above questions. In the Riacho do Pontal belt and in the western sector of the Sergipano belt, the neoproterozoic suture of the collision of the Sul domain of the BP with the Sanfranciscana plate (SFP) is correlated with an expressive dipolar gravity anomaly. The positive lobule of this anomaly is due to the BP lower continental crust uplifting whilst the negative lobule is due to the supracrustal nappes overthrusting the SFP. In the eastern sector of the Sergipano belt, this dipolar gravity anomaly does not exist. However the suture still can be identified at the southern sector of the Marancó complex arc, alongside of the Porto da Folha shear zone, where the SFP N-S geophysical alignments are truncated. The boundary associated to the collision of the Ceará domain of the BP with the West African craton is also correlated with a dipolar gravity anomaly. The positive lobule of this anomaly coincides with the Sobral-Pedro II shear zone whilst the negative lobule is associated with the Santa Quitéria magmatic arc. Judging by their geophysical signatures, the major BP internal boundaries are: i)the western sector of the Pernambuco shear zone and the eastern continuation of this shear zone as the Congo shear zone, ii) the Patos shear zone, and iii) the Jaguaribe shear zone and its southwestern continuation as the Tatajuba shear zone. These boundaries divide the BP in five tectonic domains in the geophysical criteria: Sul, Transversal, Rio Grande do Norte, Ceará, and Médio Coreaú. The Sul domain is characterized by geophysical signatures associated with the BP and SFP collision. The fact that Congo shear zone is now proposed as part of the Transversal domain boundary implies an important change in the original definition of this domain. The Rio Grande do Norte domain presents a highly magnetized crust resulted from the superposition of precambrian and phanerozoic events. The Ceará domain is divided by the Senador Pompeu shear zone in two subdomains: the eastern one corresponds to the Orós-Jaguaribe belt and the western one to the Ceará-Central subdomain. The latter subdomain exhibits a positive ENE-W SW gravity anomaly which was associated to a crustal discontinuity. This discontinuity would have acted as a rampart against to the N-S Brasiliano orogenic nappes. The Médio Coreaú domain also presents a dipolar gravity anomaly. Its positive lobule is due to granulitic rocks whereas the negative one is caused by supracrustal rocks. The boundary between Médio Coreaú and Ceará domains can be traced below the Parnaíba basin sediments by its geophysical signature. The joint analysis of free air anomalies, free air admittances, and effective elastic thickness estimates (Te) revealed that the Brazilian East and Equatorial continental margins have quite different elastic properties. In the first one 10 km < Te < 20 km whereas in the second one Te ≤ 10 km. The weakness of the Equatorial margin lithosphere was caused by the cenozoic magmatism. The BP continental margin presents segmentations; some of them have inheritance from precambrian structures and domains. The segmentations conform markedly with some sedimentary basin features which are below described from south to north. The limit between Sergipe and Alagoas subbasins coincides with the suture between BP and SFP. Te estimates indicates concordantly that in Sergipe subbasin Te is around 20 km while Alagoas subbasin has Te around 10 km, thus revealing that the lithosphere in the Sergipe subbasin has a greater rigidity than the lithosphere in the Alagoas subbasin. Additionally inside the crust beneath Sergipe subbasin occurs a very dense body (underplating or crustal heritage?) which is not present in the crust beneath Alagoas subbasin. The continental margin of the Pernambuco basin (15 < Te < 25 km) presents a very distinct free air edge effect displaying two anomalies. This fact indicates the existence in the Pernambuco plateau of a relatively thick crust. In the Paraíba basin the free air edge effect is quite uniform, Te ≈ 15 km, and the lower crust is abnormally dense probably due to its alteration by a magmatic underplating in the Cenozoic. The Potiguar basin segmentation in three parts was corroborated by the Te estimates: in the Potiguar rift Te ≅ 5 km, in the Aracati platform Te ≅ 25 km, and in the Touros platform Te ≅ 10 km. The observed weakness of the lithosphere in the Potiguar rift segment is due to the high heat flux while the relatively high strength of the lithosphere in the Touros platform may be due to the existence of an archaean crust. The Ceará basin, in the region of Mundaú and Icaraí subbasins, presents a quite uniform free air edge effect and Te ranges from 10 to 15 km. The analysis of the Bouguer admittance revealed that isostasy in BP can be explained with an isostatic model where combined surface and buried loadings are present. The estimated ratio of the buried loading relative to the surface loading is equal to 15. In addition, the lower crust in BP is abnormally dense. These affirmations are particularly adequate to the northern portion of BP where adherence of the observed data to the isostatic model is quite good. Using the same above described isostatic model to calculate the coherence function, it was obtained that a single Te estimate for the entire BP must be lower than 60 km; in addition, the BP north portion has Te around 20 km. Using the conventional elastic flexural model to isostasy, an inversion of crust thickness was performed. It was identified two regions in BP where the crust is thickened: one below the Borborema plateau (associated to an uplifting in the Cenozoic) and the other one in the Ceará domain beneath the Santa Quitéria magmatic arc (a residue associated to the Brasiliano orogenesis). On the other hand, along the Cariri-Potiguar trend, the crust is thinned due to an aborted rifting in the Cretaceous. Based on the interpretation of free air anomalies, it was inferred the existence of a large magmatism in the oceanic crust surrounding the BP, in contrast with the incipient magmatism in the continent as shown by surface geology. In BP a quite important positive geoid anomaly exists. This anomaly is spatially correlated with the Borborema plateau and the Macaú-Queimadas volcanic lineament. The integrated interpretation of geoid height anomaly data, global shear velocity model, and geologic data allow to propose that and Edge Driven Convection (EDC) may have caused the Cenozoic magmatism. The EDC is an instability that presumably occurs at the boundary between thick stable lithosphere and oceanic thin lithosphere. In the BP lithosphere, the EDC mechanism would have dragged the cold lithospheric mantle into the hot asthenospheric mantle thus causing a positive density contrast that would have generated the main component of the geoid height anomaly. In addition, the compatibility of the gravity data with the isostatic model, where combined surface and buried loadings are present, together with the temporal correlation between the Cenozoic magmatism and the Borborema plateau uplifting allow to propose that this uplifting would have been caused by the buoyancy effect of a crustal root generated by a magmatic underplating in the Cenozoic

A história do intemperismo na Província Borborema Oriental, Nordeste do Brasil: implicações paleoclimáticas e tectônicas

Until some years ago, weathering geochronology was primarily based on the K-Ar and 40Ar/39Ar dating of supergene minerals. Recent advances in the analysis of supergene goethite by the (U-Th)/He method expanded the number of suitable minerals for such purpose, as well as the time of application for weathering geochronology. This study represents the first systematic approach in Brazil, combining both the 40Ar/39Ar e (U-Th)/He methodologies to improve the knowledge on the weathering and the age of nonfossiliferous sediments. Supported by geologic and geomorphologic correlations, we identified different types of weathering profiles occurring in the interior and coastal areas of northeastern Brazil. These profiles were correlated to main regional geomorphological domains: the Borborema Plateau , the Sertaneja Depression , and the Coastal Cuestas and Plains, and respective planation surfaces, which study is fundamental to understand the landscape evolution of the northern portion of the eastern Borborema Province. The depth and stratigraphic organization of the weathering profiles in each of the geomorphological domains permitted to establish that: (i) the profiles on the highlands that cap the Borborema Surface are deeper (up to 100 m) and can be considered as typical lateritic profiles; (ii) on the lowlands that form the Sertaneja Surface , the weathering profiles are shallow and poorly developed (2-5 m deep); (iii) the profiles along the coastal area are moderately developed (up to 25 m deep), and are characterized by thick saprolites and mottle zones. Aiming to establish the timing of the evolution of northeastern Brazil, we studied 29 weathering profiles representing distinct topographic levels of the Borborema Province, from the highlands to the coast, through the analysis of 248 grains of supergene manganese oxides using laser step-heating 40Ar/39Ar geochronology. Additionally, we applied the (U-Th)/He method in 20 weathering profiles, by dating 171 grains of supergene iron oxides and hydroxides. Geochronological results for 248 grains of manganese oxides analyzed by the 40Ar/39Ar method indicate that the weathering profiles in the study area record the history of weathering from the Oligocene to the Pleistocene, with ages in the order of 31.4 ± 1.0 Ma to 0.8 ± 0.4 Ma. Dating of 171 grains of goethite by the (U-Th)/He method yielded ages ranging from 43.2 ± 4.3 Ma to 0.8 ± 0.1 Ma, suggesting the weathering processes last from the Eocene to the Pleistocene. The precipitation of supergene goethite in this interval confirms the age of the weathering processes identified from the manganese oxides record. 105 goethite grains from 8 different occurrences of the Barreiras Formation were dated by the (U-Th)/He method. Five grains collected from the cement in the Barreiras Formation sandstones, in the Lagoa Salgada and Rio do Fogo coastal cuestas, yielded ages of 17.6 ± 1.8 Ma, 17.3 ± 1.7 Ma, 16.3 ± 1.6 Ma, 16.2 ± 1.6 Ma and 13.6 ± 1.4 Ma. Results of 69 goethite grains from authigenic pisoliths collected in 7 different localities also yielded concordant ages, varying from 17.8 ± 1.8 to 7.5 ± 0.8 Ma. Results obtained from 31 detrital grains are concordant in 3 distinct localities (Lagoa Salgada, Praia da Garças e Ponta Grossa); they vary in the range of 43.2 ± 4.3 to 21.6 ± 2.2 Ma, and indicate that the maximum age for the Barreiras Formation deposition is around 22 Ma. 40Ar/39Ar results for 15 manganese oxides grains associated with the Barreiras Formation weathering profiles, in 3 different localities, vary from 13.1 ± 0.9 to 7.7 ± 0.4 Ma, in the same range of ages obtained by the (U-Th)/He method. The systematic application of the 40Ar/39Ar and (U-Th)/He methods, respectively for manganese oxides and goethites, show that the Barreiras Formation sediments were already deposited since ca. 17 Ma, and that the weathering processes were active until ca. 7 Ma ago. The ages obtained from manganese oxides collected in the Cenozoic basalts (Macau Formation) also reveal a weathering history between 19 and 7 Ma, pointing to hot and humid conditions during most of the Miocene. 40Ar/39Ar ages yielded by manganese oxides associated with the Serra do Martins Formation vary from 14.1 ± 0.4 to 10.5 ± 0.3 Ma. On the other hand, (U-Th)/He ages from iron oxides/hydroxides collected in the Serra do Martins Formation mesas vary from 20.0 ± 2.0 to 5.5 ± 0.6 Ma, indicating that those sediments are older than 20 Ma. 40Ar/39Ar and (U-Th)/He results produced in this study are in agreement with paleoclimatic interpretations based on stable isotopes and clay index values measured in the Atlantic Ocean sediments, validating the use of weathering geochronology to investigate paleoclimatic variations. The direct dating of the Barreiras Formation permitted, for the first time, confident inferences on the age of the brittle deformation recorded by this sedimentary unit in the Rio Grande do Norte and Ceará states. The first event, syn-deposition, occurred during the early Miocene; an younger event, related to the post-depositional deformation of the Barreiras Formation, is associated with tectonic activity from the very early Miocene to the Holocene. In agreement with data from other areas, results obtained in this study reveal that the depth and complexity of the weathering profiles reflect the time of exposition of such areas to the weathering agents close to the surface. However, there is no clear relationship between ages vs. altitude. The depth and the stratigraphic organization of weathering profiles in northeastern Brazil, contrary to the southeastern Brazil pattern, do not vary toward the coast. In our study area, field observations reveal the presence of ancient, thick and complex lateritic profiles preserved in the sedimentary mesas on the Borborema Plateau, as younger, narrow and incipient ones occur in the dissected areas. Geochronological results obtained for these profiles yielded older ages on the high altitudes, and younger ages in the lowlands, suggesting the scarp retreatment is the most reliable model to explain the regional landscape evolution. However, in the coastal lowlands, the relatively older ages obtained indicate that more complexes processes were involved in the modeling of the local relief

Avaliação de impacto ambiental e gestão dos recursos natuarias no estuário Apodi Mossoró, nordeste do Brasil

The aim of this study is to investigate the eco-environmental vulnerability, its changes, and its causes to develop a management system for application of eco-environmental vulnerability and risk assessment in the Apodi-Mossory estuary, Northeast Brazil. This analysis is focused on the interference of the landscape conditions, and its changes, due to the following factors: the oil and natural gas industry, tropical fruits industry, shrimp farms, marine salt industry, occupation of the sensitive areas; demand for land, vegetation degradation, siltation in rivers, severe flooding, sea level rise (SLR), coastal dynamics, low and flat topography, high ecological value and tourism in the region and the rapid growth of urbanization. Conventional and remote sensing data were analyzed using modeling techniques based on ArcGIS, ER-Mapper, ERDAS Imagine and ENVI software. Digital images were initially processed by Principal Component Analysis and transformation of the maximum fraction of noise, and then all bands were normalized to reduce errors caused by bands of different sizes. They were integrated in a Geographic Information System analysis to detect changes, to generate digital elevation models, geomorphic indices and other variables of the study area. A three band color combination of multispectral bands was used to monitor changes of land and vegetation cover from 1986 to 2009. This task also included the analysis of various secondary data, such as field data, socioeconomic data, environmental data and prospects growth. The main objective of this study was to improve our understanding of eco-environmental vulnerability and risk assessment; it´s causes basically show the intensity, its distribution and human-environment effect on the ecosystem, and identify the high and low sensitive areas and area of inundation due to future SLR, and the loss of land due to coastal erosion in the Apodi-Mossoró estuary in order to establish a strategy for sustainable land use. The developed model includes some basic factors such as geology, geomorphology, soils, land use / land cover, vegetation cover, slope, topography and hydrology. The numerical results indicate that 9.86% of total study area was under very high vulnerability, 29.12% high vulnerability, 52.90% moderate vulnerability and 2.23% were in the category of very low vulnerability. The analysis indicates that 216.1 km² and 362.8 km² area flooded on 1m and 10m in sea levels respectively. The sectors most affected were residential, industrial and recreational areas, agricultural land, and ecosystems of high environmental sensitivity. The results showed that changes in eco-environmental vulnerability have a significant impact on the sustainable development of the RN state, since the indicator is a function of sensitivity, exposure and status in relation to a level of damage. The model were presented as a tool to assist in indexing vulnerability in order to optimize actions and assess the implications of decisions makers and policies regarding the management of coastal and estuarine areas. In this context aspects such as population growth, degradation of vegetation, land use / land cover, amount and type of industrialization, SLR and government policies for environmental protection were considered the main factors that affect the eco-environmental changes over the last three decades in the Apodi-Mossoró estuary.

Geologia, Geocronologia, Geoquímica e Petrogênese das Rochas Ígneas Cretácicas da Província Magmática do Cabo e suas Relações com as Unidades Sedimentares da Bacia de Pernambuco (NE do Brasil)

The area studied forms a thin NNE-directed belt situated south of Recife town (Pernambuco state), northeastern Brazil. Geologically, it comprises the Pernambuco Basin (PB), which is limited by the Pernambuco Lineament to the north, the Maragogi high to the south and the Pernambuco Alagoas massif to the west, all of them with Precambrian age. This thesis reports the results obtained for the Cabo Magmatic Province (CMP), aiming the characterization of the geology, stratigraphy, geochronology, geochemistry and petrogenesis of the Cretaceous igneous rocks presented in the PB. The PB is composed of the Cabo Formation (rift phase) at the base (polymictic conglomerates, sandstones, shales), an intermediate unit, the Estiva Formation (marbles and argillites), and, at the top, the Algodoais Formation (monomictic conglomerates, sandstones, shales). The CMP is represented by trachytes, rhyolites, pyroclastics (ignimbrites), basalts / trachy-andesites, monzonites and alkali-feldspar granite, which occur as dykes, flows, sills, laccoliths and plugs. Field observations and well descriptions show that the majority of the magmatic rocks have intrusive contacts with the Cabo Formation, although some occurrences are also suggestive of synchronism between volcanism and siliciclastic sedimentation. 40Ar/39Ar and zircon fission tracks for the magmatic rocks indicate an average age of 102 r 1 Ma for the CMP. This age represents an expressive event in the province and is detected in all igneous dated materials. It is considered as a minimum age (Albian) for the magmatic episode and the peak of the rift phase in the PB. The 40Ar/39Ar dates are about 10-14 Ma younger than published palynologic ages for this basin. Geochemically, the CMP may be divided in two major groups; i) a transitional to alkaline suite, constituted by basalts to trachy-andesites (types with fine-grained textures and phenocrysts of sanidine and plagioclase), trachytes (porphyrytic texture, with phenocrysts of sanidine and plagioclase) and monzonites; ii) a alkaline suite, highly fractionated, acidic volcano-plutonic association, formed by four subtypes (pyroclastic flows ignimbrites, fine-to medium-grained rhyolites, a high level granite, and later rhyolites). These four types are distinguished essentially by field aspects and petrographic and textural features. Compatible versus incompatible trace element concentrations and geochemical modeling based on both major and trace elements suggest the evolution through low pressure fractional crystallization for trachytes and other acidic rocks, whereas basalts / trachy-andesites and monzonites evolved by partial melting from a mantle source. Sr and Nd isotopes reveal two distinct sources for the rocks of the CMP. Concerning the acidic ones, the high initial Sr ratios (ISr = 0.7064-1.2295) and the negative HNd (-0.43 to -3.67) indicate a crustal source with mesoproterozoic model ages (TDM from 0.92 to 1.04 Ga). On the other hand, the basic to intermediate rocks have low ISr (0.7031-0.7042) and positive HNd (+1.28 to +1.98), which requires the depleted mantle as the most probable source; their model ages are in the range 0.61-0.66 Ga. However, the light rare earth enrichment of these rocks and partial melting modeling point to an incompatible-enriched lherzolitic mantle with very low quantity of garnet (1-3%). This apparent difference between geochemical and Nd isotopes may be resolved by assuming that the metasomatizing agent did not obliterate the original isotopic characteristics of the magmas. A 2 to 5% partial melting of this mantle at approximately 14 kbar and 1269oC account very well the basalts and trachy-andesites studied. By using these pressure and temperatures estimates for the generation of the basaltic to trachy-andesitic magma, it is determined a lithospheric stretching (E) of 2.5. This E value is an appropriated estimate for the sub-crustal stretching (astenospheric or the base of the lithosphere?) region under the Pernambuco Basin, the crustal stretching probably being lower. The integration of all data obtained in this thesis permits to interpret the magmatic evolution of the PB as follows; 1st) the partial melting of a garnet-bearing lherzolite generates incompatible-enriched basaltic, trachy-andesitic and monzonitic magmas; 2nd) the underplating of these basaltic magmas at the base of the continental crust triggers the partial melting of this crust, and thus originating the acidic magmas; 3rd) concomitantly with the previous stage, trachytic magmas were produced by fractionation from a monzonitic to trachy-andesitic liquid; 4th) the emplacement of the several magmas in superficial (e.g. flows) or sub-superficial (e.g. dykes, sills, domes, laccoliths) depths was almost synchronically, at about 102 r 1 Ma, and usually crosscutting the sedimentary rocks of the Cabo Formation. The presence of garnet in the lherzolitic mantle does not agree with pressures of about 14 kbar for the generation of the basaltic magma, as calculated based on chemical parameters. This can be resolved by admitting the astenospheric uplifting under the rift, which would place deep and hot material (mantle plume?) at sub-crustal depths. The generation of the magmas and their subsequent emplacement would be coupled with the crustal rifting of the PB, the border (NNE-SSW directed) and transfer (NW-SE directed) faults serving as conduits for the magma emplacement. Based on the E parameter and the integration of 40Ar/39Ar and palynologic data it is interpreted a maximum duration of 10-14 Ma for the rift phase (Cabo Formation clastic sedimentation and basic to acidic magmatism) of the PB

Estimativa de espessura crustal na Província Borborema (NE/Brasil) através de função do recpetor

Crustal thickness and VP/VS estimates are essential to the studies of subsurface geological structures and also to the understanding of the regional tectonic evolution of a given area. In this dissertation, we use the Langston´s (1979) Receiver Function Method using teleseismic events reaching the seismographic station with angles close to the vertical. In this method, the information of the geologic structures close to the station is isolated so that effects related to the instrument response and source mechanics are not present. The resulting time series obtained after the deconvolution between horizontal components contains the larger amplitude referring to the P arrival, followed by smaller arrival caused by the reverberation and conversion of the P-wave at the base of the crust. We also used the HK-Stacking after Zhu & Kanamori (2000) to obtain crustal thickness and Vp/VS estimates. This method works stacking receiver functions so that the best estimates of crustal thickness and Vp/VS are found when the direct P, the Ps wave and the first multiple are coherently stacked. We used five broadband seismographic stations distributed over the Borborema Province, NE Brazil. Crustal thickness and Vp/VS estimates are consistent with the crust-mantle interface obtained using gravity data. We also identified crutal thickening in the NW portion of the province, close to Sobral/CE. Towards the center-north portion of the province, there is an evident crustal thinning which coincides with a geological feature consisting of an alignment of sedimentary basins known as the Cariris-Potiguar trend. Towards the NE portion of the province, in Solânea/PB and Agrestina/PE regions, occurs a crustal thickening and a systematic increase in the VP/VS values which suggest the presence of mafic rocks in the lower crust also consistent with the hypothesis of underplating in the region

Análise de terrenos na porção setentrional da Província Borborema, NE do Brasil: integração de dados geológicos e gravimétricos

It is presently assumed that the Borborema Province resulted from a complex collisional process associated with the convergent movement of plates, possibly involving amalgamation and accretion of microplates. This process was consolidated at the end of the Brasiliano event. It is investigated the possible limits for the tectonostratigraphic terranes in the northern portion of the province based on an integrated study of geological and gravity data. The study area comprises the portion of the Borborema Province located north of the Patos Lineament, limited by longitudes 33º00 W and 43º29 44"W and latitudes 1º36 S and 8º00 S. A revision of the regional geology allowed to identify areas presenting contrasting geological attributes, possibly representing different terranes whose limits are always shear zones of Brasiliano-age. The Sobral-Pedro II shear zone is the only one undoubtedly presenting geological attributes of sutures zones. The other shear zones are very likely associated with a geodinymic context of accretion, involving oblique collisions (docking), transcurrent and/or transforming sutures, and deep intracrustal shear zones. The gravity data contributed as a tool to identify strong lateral contrasts of density inside the upper crust possibly associated with crustal blocks tectonically juxtaposed. The dominant long wavelength anomaly in the Bouguer anomaly map is an expressive gradient, grossly parallel to the continental margin, caused by density variation across the crust-mantle interface in the transition from the continental crust to the oceanic crust originated by the separation between South America and Africa. Medium to small wavelength anomalies are due to intracrustal heterogeneities such as different Precambrian crustal blocks, Brasiliano-age granites and Mesozoic sedimentary basins. A regional-residual separation of the Bouguer anomaly map was performed in order to enhance in the residual map the effect due to intracrustal heterogeneities. The methodology used for this separation was a robust polinomial fitting. The inversion of residual gravity field resulted in a density contrast map (Δρ), in an equivalent layer that provided more accurated anomalies contours and consolidated the model which the sources of residual anomalies are located in the upper part of the present crust. Based on the coincidence of gravity lineaments in the residual map and Brasiliano shear zones, and using additional geological information, the following shear zones are proposed as limits between terranes: Patos shear zone, Sobral-Pedro II shear zone, Picuí-João Câmara shear zone, Remígio-Pocinhos shear zone, Senador Pompeu shear zone, Tauá shear zone, and Portalegre shear zone. Based on the geological/geophysical information it is attributed a higher level of confidence to the first three proposed limits(Patos, Sobral Pedro II, and Picuí-João Câmara shear zones). From west to east, these shear zones individualize the following terranes: Northwest of Ceará terrane, Central Ceará terrane, Tauá terrane, Orós-Jaguaribe terrane, Seridó terrane, and São José de Campestre terrane. In our study, the Rio Piranhas and Patos terranes are questioned because their previously proposed limits do not present good geological and gravimetric evidences. On the other hand, the previously proposed Cearense terrane is now subdivided into Central Ceará and Tauá terranes. Two residual gravity profiles located in the Seridó belt were interpreted using 2 ½ D direct gravity modeling. The main result of the modeling process is that all anomalies, with the exception of one, can be explained by outcroppring bodies, therefore restricted to the upper part of the present crust

Pirometamorfismo nos arenitos da Formação Açu, Bacia Potiguar, NE do Brasil

Pyrometamorphism results from conditions of high temperatures and very low pressures provoked by the intrusion of hypabyssal basic bodies into sedimentary or metassedimentary hosting rocks. The onshore portion of the Potiguar Basin in NE Brazil offers examples of this type of metamorphism nearby the contacts of Paleogene to Neogene plugs, sills and dikes of diabases and basalts crosscutting sandstones, siltstones and shales of the Açu Formation (Albian-Cenomanian). The thermal effects over these rocks are reflected on textures and minerals assemblages that characterize the sanidinite facies of metamorphism, often with partial melting of the feldspathic and mica-rich matrix. The liquid formed is potassic and peraluminous, with variably colored rhyolitic glass (colorless, yellow, brown) comprising microcrystals of tridymite, sanidine and clinoenstatite, besides residual detrital clasts of quartz and rarely zircon, staurolite and garnet. Lenses of shale intercalated within the sandstones display crystallites of Fe-cordierite (sekaninaite), mullite, sanidine, armalcolite (Fe-Ti oxide) and brown spinel. The rocks formed due to the thermal effect of the intrusions are called buchites for which two types are herein described: a light one derived from feldspathic sandstone and siltstone protoliths; and a dark one derived from black shale protoliths. Textures indicating partial melting and minerals such as sanidine, mullite, tridymite and armalcolite strongly demonstrate that during the intrusion of the basic bodies the temperature reached 1,000-1,150°C, and was followed by quenching. Cooling of the interstitial melts has as consequences the closure of pores and decrease of the permeability of the protolith, which varies from about 17-11% in the unaffected rocks to zero in the thermally modified types. Although observed only at contacts and over small distances, the number of basic intrusions hosted within the Potiguar Basin in both onshore and offshore portions leaves opened the possibility of important implications of the thermal effects over the hydrocarbon exploration in this area as well in other Cretaceous and Paleozoic basins in Brazil