Análises estratigráfica e estrutural da Seção Rifte (Valanginiano ao Barremiano) na área do levantamento sísmico 3D de baixo vermelho, Bacia Potiguar emersa

Baixo Vermelho area, situated on the northern portion of Umbuzeiro Graben (onshore Potiguar Basin), represents a typical example of a rift basin, characterized, in subsurface, by the sedimentary rift sequence, correlated to Pendência Formation (Valanginian-Barremian), and by the Carnaubais fault system. In this context, two main goals, the stratigraphic and the structural analysis, had guided the research. For this purpose, it was used the 3D seismic volume and eight wells located in the study area and adjacencies. The stratigraphic analysis of the Valanginian-Barremian interval was carried through in two distinct phases, 1D and 2D, in which the basic concepts of the sequence stratigraphy had been adapted. In these phases, the individual analysis of each well and the correlation between them, allowed to recognize the main lithofacies, to interpret the effective depositional systems and to identify the genetic units and key-surfaces of chronostratigraphic character. The analyzed lithofacies are represented predominantly by conglomerates, sandstones, siltites and shales, with carbonate rocks and marls occurring subordinately. According to these lithofacies associations, it is possible to interpret the following depositional systems: alluvial fan, fluvio-deltaic and lacustrine depositional systems. The alluvial fan system is mainly composed by conglomerates deposits, which had developed, preferentially in the south portion of the area, being directly associated to Carnaubais fault system. The fluvial-deltaic system, in turn, was mainly developed in the northwest portion of the area, at the flexural edge, being characterized by coarse sandstones with shales and siltites intercalated. On the other hand, the lacustrine system, the most dominant one in the study area, is formed mainly by shales that could occur intercalated with thin layers of fine to very fine sandstones, interpreted as turbidite deposits. The recognized sequence stratigraphy units in the wells are represented by parasequence sets, systems tracts and depositional sequences. The parasequence sets, which are progradational or retrogradational, had been grouped and related to the systems tracts. The predominance of the progradation parasequence sets (general trend with coarsening-upward) characterizes the Regressive Systems Tract, while the occurrence, more frequently, of the retrogradation parasequence sets (general trend with finning-upward) represents the Transgressive System Tract. In the seismic stratigraphic analysis, the lithofacies described in the wells had been related to chaotic, progradational and parallel/subparallel seismic facies, which are associated, frequently, to the alluvial fans, fluvial-deltaic and lacustrine depositional systems, respectively. In this analysis, it was possible to recognize fifteen seismic horizons that correspond to sequence boundaries and to maximum flooding surfaces, which separates Transgressive to Regressive systems tracts. The recognition of transgressive-regressive cycles allowed to identify nine, possibly, 3a order deposicional sequences, related to the tectonic-sedimentary cycles. The structural analysis, in turn, was done at Baixo Vermelho seismic volume, which shows, clearly, the structural complexity printed in the area, mainly related to Carnaubais fault system, acting as an important fault system of the rift edge. This fault system is characterized by a main arrangement of normal faults with trend NE-SO, where Carnaubais Fault represents the maximum expression of these lineations. Carnaubais Fault corresponds to a fault with typically listric geometry, with general trend N70°E, dipping to northwest. It is observed, throughout all the seismic volume, with variations in its surface, which had conditioned, in its evolutive stages, the formation of innumerable structural features that normally are identified in Pendencia Formation. In this unit, part of these features is related to the formation of longitudinal foldings (rollover structures and distentional folding associated), originated by the displacement of the main fault plan, propitiating variations in geometry and thickness of the adjacent layers, which had been deposited at the same time. Other structural features are related to the secondary faultings, which could be synthetic or antithetic to Carnaubais Fault. In a general way, these faults have limited lateral continuity, with listric planar format and, apparently, they play the role of the accomodation of the distentional deformation printed in the area. Thus, the interaction between the stratigraphic and structural analysis, based on an excellent quality of the used data, allowed to get one better agreement on the tectonicsedimentary evolution of the Valanginian-Barremian interval (Pendência Formation) in the studied area

A Cabana Umbamdista Pai Joaquim de Angola: frente a intolerância a Umbanda na Cidade do Natal/RN

This dissertation presents an attempt to register the initial steps of african-Brazilian religion Umbanda in the city of Natal, capital of Rio Grande do Norte, from a case study of Cabana Umbanda Pai Joaquim de Angola, represented by its maintainer, umbanda of the priest José Clementino. The main objective is to record the memories of fans in aspects of its tradition, experience social and cultural religious building, in an attempt to show the religious hatred with practitioners of Umbanda. Used to: in audio recordings of festivals and rituals, narratives about the memories and stories of employees and their explanations, photographs, diary entries in the field, participant observation and interviews available. The analysis referred to in umbanda Natal / RN, was based on field research as a product of the visits that took place between the years 2006 to 2009 in Terreiro de Umbanda Pai Joaquim de Angola, located in the neighborhood of Rocas.

Trabalho e formação docente na rede municipal de ensino de natal

The study Teacher work and education in the municipal schools of Natal objectifies the analysis of the education and work conditions of the teachers in the municipal schools of Natal, placing them within the scenario of the public policies outlined for Basic Education (2005-2010). The thesis is based on the perspective that the educational reforms implemented by the Brazilian government in an attempt to answer to the new contextual demands originated from the world of work and globalization, demanding increasingly higher levels of qualification and constant extension of the teaching functions in school from the teachers, have been configured withal as a strategy for intensifying the teacher s work. The empirical field of study was constituded by thirteen municipal schools that offer basic education. Four hundred and seventeen teacher subjects that work in the municipal school system of Natal, two representatives of the Secretaria Municipal de Educação de Natal (SME)1 that work in the pedagogical team and one representative of the Sindicato dos Trabalhadores em Educação do Rio Grande do Norte2 took part in the study. The procedures/instruments used in the research were: bibliographic review, document research, questionnaires and recording of information in a field journal. The study confirmed that the majority of the teachers that work in the municipal school system were admitted by means of public entry exams, therefore meeting the requirements set by Law 9.394/96. Most of the teachers have the initial education demanded to work in basic education, although with some limitations due to the fact that they do not correspond to the needs of the educational system. The SME has a plan for continued training of the teachers in accordance to the current ideas defended by researchers of this field. There is, although, a disconnection between the purpose of the plan and the training strategies, because, in truth, predominate repetitive and specific actions that do not contemplate the training needs of the teachers, nor the demands of the system. Although the work conditions are evaluated, by the teachers, as relatively good, limits in relation to the physical structure of the schools are observed (dirty walls with holes in them, broken ceiling fans, old chairs and desks, old and stained black boards, inadequate restroom installations, poor maintenance of the computers, amongst other items). It was also verified the an increase in the functions of the teachers and an intensification of their work, materialized through an overburden of activities undertaken daily at school (and outside of it) and through the demand in taking part in activities that go beyond those inherent to the teaching process, such as the elaboration of political-pedagogical projects, participation in collegiate, registration of student information solicited by the SME and the participation in commissions, has been happening

Análise dos fatores responsáveis pela alta salinidade do aqüífero fissural da microbacia da Riacho do Feijão - Pedro Avelino/RN

The fissures aquifer northeast semi-arid Brazilian, present high text frequently of leave, with of low a hídric availability. The research has as objective main to analyze the components that inside influence in the salinity of the waterbearing fissures of an evaluation physicist-chemistry of the water, leading in consideration the physical interventions of the environment. One used techniques of interpretation of image of Landsat satellite -1999 and delimitation of the micro basin through the topographical map SUDENE. One identified waters of the NaCl type with Ca++ and Mg++ in secondary concentrations. The analyzed wells (15), had presented an average salinity of 5.147 mg/L of STD and a well only supplies drinking waters with 319 mg/L of STD. The recharge of the aquifer one if carries through for infiltration in the open fracture of ortognaisse it migmatization. The type and directions of the fracture do not control the STD. Relations between salinity and out let do not exist. The quality of the well of low salinity is identical the superficial waters (aquifer dam and alluvial). The studies of the meteoric erosion processes had evidenced that in the transformations of the rock in ground, the Ca++ and Na+ are taken for superficial waters. The treatment of the data chemical showed that the grade of Na+, Ca++, Mg++ and Cl-are controlled for the evaporation process, from only water that would have the qualities of superficial waters or the well of low salinity. Already the HCO3-grade is controlled for the precipitation of the dolomite. The STD of this aquifer one would be consequence of the high tax of evaporation of dams constructed in regions of plain topography. You leave them precipitated in deep argillaceous ones dry dams are led for the aquifer in first rains. The research suggests some recommendations for the use and exploitation of the water salinity in piscicultura, carcinicultura, culture of the grass-salt (Atriplex sp), among others

Quem nasce em campina grande é campinense : futebol e sociabilidade na rainha da borborema (1954-1965)

This study aims to historicize a problem: How Campinense Club, club social of the city of Campina Grande, became a popular club? This guild was founded in 1915 by a group of graduates, which they called "Campinense" a social club dedicated to the enjoyment of the city's elites. To investigate the mechanisms that have led to this popularity, was chosen that includes a period from 1954 to 1965, when it was created a department where the professional football club won a string of six consecutive championships, considered the main achievement of its history sports. Were used as research sources Borborema the Journal, a newspaper founded in 1957 and that during the period in question, was the spokesman of the main political groups in the city, which on many occasions were the sponsors of the clubs the same. This newspaper had a daily sports column and introduced the red-black team to Paraíba. Were used, although the club's meeting minutes taken as official documents, which allowed it to be mounted on a puzzle of the club's events, since the information about the Campinense present rather fragmented. Finally, respondents were fans, athletes and leaders who, through his lines in a way pointed out other possibilities such as a club, believed to be aristocratic, has become a passion among the fans, giving rise to this conception to be one that Campinense broke with the established elites of the city.

Caracterização geológico-geofísica do meio aqüífero fissural : uma contribuição aos modelos de fluxo e armazenamento de água subterrânea

Northeastern Brazil is mainly formed by crystalline terrains (around 60% in area). Moreover, this region presents a semi-arid climate so that it is periodically subject to drought seasons. Furthermore, ground water quality extracted fromwells usually presents poor quality because of their high salinity contents. Nevertheless, ground water is still a very important source of water for human and animal consumption in this region. Well sitting in hard rocks terrains in Northeastern Brazil offers a mean success index of aboul 60%, given that a successful siting is defined by a well producing at least 0.5 m³/h. This low index reveals lack of knowledga about the true conditions of storage and percolation of ground water in crystalline rocks. Two models for structures storing and producing ground water in crystalline rocks in Northeastem Brazil have been proposed in the literature. The first model,tradnionally used for well sitting since the sixties are controlled by faults or fractures zones. This model is commonly referred, in Brazilian hydrogeological literature, as the "creek-crack" model (riacho-fenda in Portuguese). Sites appearing to present dense drainage network are preferred for water well siting - particularly at points where the drainages cross-cul each other. Field follow up work is usually based only on geological criteria. The second model is the "eluvio-alluvial through" (calha eluvio-aluvionar in Portuguese); it is also described in the literature but it is not yet incorporated in well sitting practice. This model is based on the hypothesis that reclilinear drainages can also be controlled by the folietion of the rock. Eventually, depending upon the degree of weathering, a through-shaped structure filled with sediments (alluvium and regolith) can be developed which can store and water can be produced from. Using severalfield case studies, this Thesis presents a thorough analysis ofthe two above cited models and proposes a new model. The analysis is based on an integrated methodological approach using geophysics and structural geology. Both land (Resitiviy and Ground Penetrating Radar- GPR) and aerogeophysical (magnetics and frequency domain eletromagnetics) surveys were used. Slructural analysis emphasized neolectonic aspects; in general, itwas found that fractures in the E-W direction are relatively open, as compared to fracturas inthe N-S direction, probably because E-W fractures were opened by the neotectonic stress regime in Northeastern Brazil, which is controlled by E-W compression and N-S extension. The riacho-fenda model is valid where drainages are controlled by fractures. The degree of fracturing and associated weathering dictale the hydrogeological potential of the structure. Field work in structural analogues reveals that subvertical fractures show consistent directions both in outcrop and aerophotograph scales. Geophysical surveys reveal subvertical conductive anomalies associated to the fracture network controlling the drainage; one of the borders of the conductive anomaly usually coincide wih the drainage. An aspect of particular importance to the validation of fracture control are the possible presence of relalively deep conductive anomalies wihoul continuation or propagalion to the surface. The conductive nature of lhe anomaly is due to the presence of wealhered rock and sedirnenls (alluvium and/or regolilh) storing ground waler which occur associated to the fracture network. Magnetic surveys are not very sensisnive to these structures.lf soil or covering sedirnents are resislive (> 100 Ohm.m), GPR can ba used to image precisely lhe fracture network. A major limialion of riacho-fenda model, revealed by GPR images, is associated to the fact thal subhorizontal fractures do play a very important role in connecting the fracture network, besides connect shallow recharge zones to relalively deep subvertical frecture zones. Iffractures play just a secondary control on the drainage, however, r/acho-fenda model may have a very limiled validny; in these cases, large portions oflhe drainage do nol coincide wilh frectures and mosl oflhewells localed in lhe drainage surrounding would resull dry. Usually, a secondary conlrol on lhe drainage by Ihefraclure networkcan be revealed only wilh detailed geophysical survey. The calha elClv1o-aluvlonarmodel is valid where drainages are conlrolled by folialion. The degree 01 wealhering 01 lhe lolialion planes dictales lhe hydrogeological polenlial 01 lhe slruclure. Outcrop analysis reveals Ihal lolialion and drainage direclions are parallel and Ihal no Iraclures, orfraclures wilh diflerent directions 01 lhe drainage direclion occur. Geophysical surveys reveal conduclive anomalies in a slab lorm associaled 10 lhe Ihrough 01 lhe wealhered rock and sedimenls (alluvium and/or regolith). Magnelic surveys can ofler a very good conlrol on lolialion direclion. An importanl aspect 10 validale lolialion conlrol are lhe presence 01 conductive anomalies showing shallow and deep portions area which are linked. Illhere is an exlensive soil cover, r/acho-fenda and calha eIClv1o-aluv/onar conlrols can be easily misinlerpreled in lhe absence 01 geophysical conlrol. Certainly, Ihis lacl could explain at leasl a part of lhe failure index in well sitting. The model wealhering sack (bolsllo de Intempertsmo in Portuguese) is proposed to explain cases where a very inlensive wealhering occur over lhe crystalline rock so Ihal a secondary inlerslilial porosity is crealed. The waler is Ihen stored in lhe porous of lhe regolilh in a similar mannerlo sedimentary rocks. A possible example ofthis model was delecled by using land geophysical survey where a relalivelyvery deep isolaled conduclive anomaly, in a slab form, was delected. Iflhis structure does store ground waler, certainly Ihere must be a link 01 lhe deep slructure wilh lhe surface in orderlo provide walerfeeding. This model mighl explain anomalous waler yields as greal as 50 m³/h Ihalsomelimescan occur in crystalline rocks in Northeaslern Brazil

Tecttôniica póss--riifftte na Baciia Pottiiguar

The study of Brazilian sedimentary basins concentrates on their rift phase, whereas the Post-rift phase has been considered a tectonic quiescent period. The post-rift sequence of the Potiguar Basin, in the far northeastern Brazil, was once considered little deformed, however several studies have shown how that it was affected by major fault systems. The purpose of this thesis is to characterize the post-rift tectonic. The specific objectives are: to characterize the Neogene and Quaternary sedimentary units that outcrop of the Potiguar Basin; to show how the NW-SEtrending Afonso Bezerra Faults System deformed outcrop rocks in the Basin; to describe soft-sediment deformation in gravels of the Quaternary Alluvial Deposits from Açu River. Facies analyses, grain-size studies, luminescence dating, remote sensing, structural mapping, shallow geophysics (georadar), paleostress and petrography were carried out. The structural mapping and the georadar sections indicated that the Carnaubais and Afonso Bezerra fault systems formed fractures, silicified and non-silicified faults or deformation bands, affecting mainly the Açu, Jandaíra and Barreiras formations. The petrographic data indicate that the strong silicification resulted in a sealant character of the faults. Paleostress analysis indicates that two stress fields affected the Basin: the first presented N-S-trending compression, occurred from the Neocretaceous to the Miocene; the second stress field presents E-W-trending compression, acts from the Miocene to the present. It was verified once the Afonso Bezerra System Faults was reactivated in periods post-Campanian and affects all post-rift lithostratigraphic units of Potiguar Basin, including Quaternary sedimentary covers. The study about soft-sediment deformation structures indicates that they are similar in morphology and size to modern examples of seismically-induced deformation strutures in coarse sediments. TL and OSL ages indicate that sediment deposition and associated soft-sediment deformation occurred at least six times from ~352 Ka to ~9 Ka. Finally these studies demonstrate how recent is tectonics in the Basin Potiguar

Mapeamento digital de análogos a reservatórios petrolíferos: exemplos para depósitos fluviais da Unidade Açu-3 - Bacia Potiguar

In the current work are presented the results about the study of digital mapping of analogs referents the fluvial oil reservoirs in the Açu Formation. With the regional recognizing in the south corner of Potiguar Basin was selected a area of 150 Km square in the west of Assu city. In this area was chosen the outcrops for the digital mapping and from the data fields and remote sensors were done the depositional architectural for the fluvial deposits, which it was named coarse meandering fluvial systems. In the deposits were individualized 3 (three) fluvial cycles, which they was separated by bounding surface of fifth order. Such cycles are preferentially sandy, with fining-upward sequence finished in flood plain deposits. Inner of the sandy levels of the filling channels were characterized least cycles, normaly incomplete, constituted by braided sandy bodies and bounding surfaces of fourth order. In the mapped area was chosen a outcrop with great exposition, where it was possible to see tipical deposits of filling channel and was in this outcrop that was done the digital mapping. In this outcrop was used diverse technics and tools, which they integrated sedimentological, altimetric (GPS, Total Station), LIDAR (Light Detection and Ranging), digital photomosaic of high resolution and of the inner geometries (Ground Penetration Radar) data sets. For the integrating, interpretation and visualization of data was used software GoCAD®. The final product of the outcrop digital mapping was the photorealistic model of part of the cliff (or slope) because the observed reflectors in the radargrams were absents. A part of bar oblique accretion was modeled according to GPR gride of 200x200 meters in the alluvial Assu river probable recent analog. With the data of inner geometries was developed the three-dimentional sedimentary architectural, where it was possible characterize sand sheet deposits and many hierarchy of braided channels. At last, simulations of sedimentary geometries and architectures of the Potiguar Basin Fluvial Reservoirs were done with PetBool software, in order to understand the capacity of this program in simulations with a lot of numbers of conditioning wells. In total, 45 simulations was acquired, where the time and the channel numbers increase in relation of the conditioning wells quantity. The deformation of the meanders was detected from the change of simulated dominion dimensions. The presence of this problem was because the relationship between the simulated dominion and the width of the meander

Estudo integrado geológico/tecnológico de rochas ornamentais: os granitos flores e jacarandá, RN

The main purpose of the present study is to integrate a geological and technological investigation of ornamental rocks of the Flores and Jacarandá granites, which are located near the Afonso Bezerra city, in the north central part of the Rio Grande do Norte State. The study area encompasses four litho-stratigrafic units: a Gneiss-Migmatitic Complex(cristalline basement), which is mainly composed of banded gneisses, usually deformed as mylonitic rocks and with several migmatic features, an Augen Gneiss, which occurs as an elongated body that constitutes the Jacarandá granite, a small granite stock, which presents a semi-circular form, named Flores granite, composed of pink, fine to medium coarse rocks, and fine to coarse alluvial sediments, which form extensive areas of large fluvial deposits. The technological characterization of the Flores and Jacarandá granites, carried out through several tests, has as the main purpose the determination of petrographic, physical, and mechanic parameters that allowed the characterization of these rocks. The test followed procedures recommended by Brazilian (ABNT Associação Brasileira de Normas Técnicas) and foreigner institutions (ASTM American Society for Testing and Materials). The petrografhic analysis indicated that the rocks investigated are granite sensu estrictu, summing an average 85-90% modal. The Flores granite is the more felsic rock, which presents mafic content ∼ 10% and monzonitic composition. The Jacarandá granite is an Augen Gneiss rock that presents sienogranitic composition and mafic modal content ∼ 15%. Several technological tests carried out (alterability, physical indices, velocity of ultrasonic wave propagation, uniaxial compression, flection resistence, Amsler desgaste, and resistence to freezing and heating) indicated that parameters and values were identical for both granites investigated. These parameters and values are consistent with the Brazilian and international standards for siliciclastic rocks of ornamental use, as well as other Brazilian ornamental granites. The analysis of all results indicates that both the Flores and Jacarandá granites present good quality, and that they are indicated for ornamental use of revetment interior and exterior of buildings

Estruturas de acumulação de água subterrânea em rochas cristalinas: estudo geofísico e geológico de casos no Estado do Rio Grande do Norte

Geological and geophysical studies (resistivity, self potential and VLF) were undertaken in the Tararaca and Santa Rita farms, respectively close to the Santo Antônio and Santa Cruz villages, eastern Rio Grande do Norte State, NE Brazil. Their aim was to characterize water acummulation structures in crystalline rocks. Based on geological and geophysical data, two models were characterized, the fracture-stream and the eluvio-alluvial through, in part already described in the literature. In the Tararaca Farm, a water well was located in a NW-trending streamlet; surrounding outcrops display fractures with the same orientation. Apparent resistivity sections, accross the stream channel, confirm fracturing at depth. The VLF profiles systematically display an alignment of equivalent current density anomalies, coinciding with the stream. Based on such data, the classical fracture-stream model seems to be well characterized at this place. In the Santa Rita Farm, a NE-trending stream display a metric-thick eluvioregolith-alluvial cover. The outcropping bedrock do not present fractures paralell to the stream direction, although the latter coincides with the trend of the gneiss foliation, which dips to the south. Geophysical data confirm the absence of a fracture zone at this place, but delineate the borders of a through-shaped structure filled with sediments (alluvium and regolith). The southern border of this structure dips steeper compared to the northern one. This water acummulation structure corresponds to an alternative model as regards to the classical fracture-stream, being named as the eluvio-alluvial trough. Its local controls are the drainage and relief, coupled with the bedrock weathering preferentially following foliation planes, generating the asymmetry of the through

Caracterização de reservatórios siliciclásticos neoaptianos: um estudo do membro carmópolis no campo de Camorim, sub-bacia de Sergipe, Brasil

The Camorim Oilfield, discovered in 1970 in the shallow water domain of the Sergipe Sub-basin, produces hydrocarbons from the Carmópolis Member of the Muribeca Formation, the main reservoir interval, interpreted as siliciclastics deposited in an alluvial-fluvial-deltaic context during a late rifting phase of Neoaptian age, in the Sergipe-Alagoas Basin. The structural setting of the field defines different production blocks, being associated to the evolution of the Atalaia High during the rift stage and subsequent reactivations, encompassing NE-SW trending major normal faults and NWEW trending secondary faults. The complexity of this field is related to the strong facies variation due to the interaction between continental and coastal depositional environments, coupled with strata juxtaposition along fault blocks. This study aims to geologically characterize its reservoirs, to provide new insights to well drilling locations in order to increase the recovery factor of the field. Facies analysis based on drill cores and geophysical logs and the 3D interpretation of a seismic volume, provide a high resolution stratigraphic analysis approach to be applied in this geodynamic transitional context between the rift and drift evolutionary stages of the basin. The objective was to define spatial and time relations between production zones and the preferential directions of fluid flow, using isochore maps that represent the external geometry of the deposits and facies distribution maps to characterize the internal heterogeneities of these intervals, identified in a 4th order stratigraphic zoning. This work methodology, integrated in a 3D geological modelling process, will help to optimize well drilling and hydrocarbons production. This methodology may be applied in other reservoirs in tectonic and depositional contexts similar to the one observed at Camorim, for example, the oil fields in the Aracaju High, Sergipe Sub-basin, which together represent the largest volume of oil in place in onshore Brazilian basins

Petrologia e geocronologia U-Pb do plúton granítico Serra da Rajada, porção central do domínio Rio Piranhas - Seridó, Província Borborema, NE do Brasil

The ediacaran plutonic activity related to the Brasilian/Pan-African orogeny is one of the most important geological features in the Borborema Province, represented along its extension by numerous batholiths, stocks, and dikes.The object of this study, the Serra Rajada Granitic Pluton (SRGP), located in the central portion of the Piranhas-Seridó River Domain is an example of this activity. This pluton has been the subject of cartographic, petrographic, geochronological and lithogeochemical studies and its rocks were characterized by two facies. First, the granitic facies were described as monzogranites consisting of K-feldspar, plagioclase (oligoclase - An23-24%), quartz and biotite (main mafic) and opaque minerals such as titanite, allanite, apatite, and zircon as accessories. Alteration minerals are chlorite, white mica and carbonate. Second, the dioritic facies consist of rocks formed by quartz diorite containing plagioclase (dominant mineral phase), quartz and K-feldspar. Biotite and amphibole are the dominant mafic minerals; and titanite, opaque minerals, allanite, zircon and apatite are the accessories. However, previous geological mapping work in the region also identified the presence of other lithostratigraphic units. These were described as gneisses and migmatites with undifferentiated amphibolite lenses related to the Caicó Complex (Paleoproterozoic) and metasedimentary rocks of the Seridó Group (Neoproterozoic) composed of paragneiss with calc-silicate lenses, muscovite quartzite and biotite schist (respectively, the Jucurutu formations, Equador and Seridó), the host rocks for the SRGP rocks. Leucomicrogranite and pegmatite dikes have also been identified, both related to the end of the Ediacaran magmatism and colluvial- eluvial and alluvial deposits related to Neogene and Quaternary, respectively. Lithogeochemical data on the SRGP granite facies, highlighted quite evolved rocks (SiO2 69% to 75%), rich in alkalis (Na2O+K2O ≥ 8.0%), depleted of MgO (≤ 0.45%), CaO (≤ 1.42%) and TiO2 (≤ 0.36%) and moderate levels of Fe2O3t (2.16 to 3.53%). They display transitional nature between metaluminous and peraluminous (predominance of the latter) with sub-alkaline/monzonitic (High K calcium-alkali) affinity. Harker diagrams show negative correlations for Fe2O3t, MgO, and CaO, indicating mafic and plagioclase fractionation. REE spectrum shows enrichment of LREE relative to heavy REE (LaN/YbN = 23.70 to 10.13), with negative anomaly in the Eu (Eu/Eu* = 0.70 to 0.23), suggesting fractionation or accumulation in the feldspars source (plagioclase). Data integration allows to correlate the SRGP rocks with those described as Calcium-Alkaline Suite of equigranular High K. The crystallization conditions of the SRGP rocks were determined from the integration of petrographic and lithogeochemical data. These data indicated intermediate to high conditions of ƒO2 (mineral paragenesis titanite + magnetite + quartz), parent magma saturated in H2O (early biotite crystallization), tardi-magmatic processes of fluids rich in ƒCO2, H2O and O2 causing part of the mineral assembly to change (plagioclase carbonation and saussuritization, biotite chloritization and opaques Sphenitization). Thermobarometrical conditions were estimated based on geochemical parameters (Zr and P2O5) and CIPW normative minerals, with results showing the liquidus minimum temperature of about800°C and the solidus temperature of approximately 700°C. The final/minimum crystallization pressure are suggested to be between 3 and 5 Kbar. The presence of zoned minerals (plagioclase and allanite) associated with lithogeochemical data in bi-log diagrams for Rb vs. Ba and Rb vs. Sr suggest the role of fractional crystallization as the dominant process in the magmatic evolution of SRGP. U-Pb Geochronological and Sm-Nd isotope studies indicated, respectively, the crystallization age of biotite monzogranite as 557 ± 13 Ma, with TDM model age of 2.36 Ga, and εNd value of -20.10 to the crystallization age, allowing to infer paleoproterozoic crustal source for the magma.

Petrologia e geocronologia U-Pb do plúton granítico Serra da Rajada, porção central do domínio Rio Piranhas - Seridó, Província Borborema, NE do Brasil

The ediacaran plutonic activity related to the Brasilian/Pan-African orogeny is one of the most important geological features in the Borborema Province, represented along its extension by numerous batholiths, stocks, and dikes.The object of this study, the Serra Rajada Granitic Pluton (SRGP), located in the central portion of the Piranhas-Seridó River Domain is an example of this activity. This pluton has been the subject of cartographic, petrographic, geochronological and lithogeochemical studies and its rocks were characterized by two facies. First, the granitic facies were described as monzogranites consisting of K-feldspar, plagioclase (oligoclase - An23-24%), quartz and biotite (main mafic) and opaque minerals such as titanite, allanite, apatite, and zircon as accessories. Alteration minerals are chlorite, white mica and carbonate. Second, the dioritic facies consist of rocks formed by quartz diorite containing plagioclase (dominant mineral phase), quartz and K-feldspar. Biotite and amphibole are the dominant mafic minerals; and titanite, opaque minerals, allanite, zircon and apatite are the accessories. However, previous geological mapping work in the region also identified the presence of other lithostratigraphic units. These were described as gneisses and migmatites with undifferentiated amphibolite lenses related to the Caicó Complex (Paleoproterozoic) and metasedimentary rocks of the Seridó Group (Neoproterozoic) composed of paragneiss with calc-silicate lenses, muscovite quartzite and biotite schist (respectively, the Jucurutu formations, Equador and Seridó), the host rocks for the SRGP rocks. Leucomicrogranite and pegmatite dikes have also been identified, both related to the end of the Ediacaran magmatism and colluvial- eluvial and alluvial deposits related to Neogene and Quaternary, respectively. Lithogeochemical data on the SRGP granite facies, highlighted quite evolved rocks (SiO2 69% to 75%), rich in alkalis (Na2O+K2O ≥ 8.0%), depleted of MgO (≤ 0.45%), CaO (≤ 1.42%) and TiO2 (≤ 0.36%) and moderate levels of Fe2O3t (2.16 to 3.53%). They display transitional nature between metaluminous and peraluminous (predominance of the latter) with sub-alkaline/monzonitic (High K calcium-alkali) affinity. Harker diagrams show negative correlations for Fe2O3t, MgO, and CaO, indicating mafic and plagioclase fractionation. REE spectrum shows enrichment of LREE relative to heavy REE (LaN/YbN = 23.70 to 10.13), with negative anomaly in the Eu (Eu/Eu* = 0.70 to 0.23), suggesting fractionation or accumulation in the feldspars source (plagioclase). Data integration allows to correlate the SRGP rocks with those described as Calcium-Alkaline Suite of equigranular High K. The crystallization conditions of the SRGP rocks were determined from the integration of petrographic and lithogeochemical data. These data indicated intermediate to high conditions of ƒO2 (mineral paragenesis titanite + magnetite + quartz), parent magma saturated in H2O (early biotite crystallization), tardi-magmatic processes of fluids rich in ƒCO2, H2O and O2 causing part of the mineral assembly to change (plagioclase carbonation and saussuritization, biotite chloritization and opaques Sphenitization). Thermobarometrical conditions were estimated based on geochemical parameters (Zr and P2O5) and CIPW normative minerals, with results showing the liquidus minimum temperature of about800°C and the solidus temperature of approximately 700°C. The final/minimum crystallization pressure are suggested to be between 3 and 5 Kbar. The presence of zoned minerals (plagioclase and allanite) associated with lithogeochemical data in bi-log diagrams for Rb vs. Ba and Rb vs. Sr suggest the role of fractional crystallization as the dominant process in the magmatic evolution of SRGP. U-Pb Geochronological and Sm-Nd isotope studies indicated, respectively, the crystallization age of biotite monzogranite as 557 ± 13 Ma, with TDM model age of 2.36 Ga, and εNd value of -20.10 to the crystallization age, allowing to infer paleoproterozoic crustal source for the magma.