A perspective on potassic and ultrapotassic rocks:Constraints on the Paleoproterozoic late to post-collisional event in the São Francisco paleocontinent

The late-to post-collisional stage in orogenic systems is characterized by the coeval existence of bimodal potassic to ultrapotassic magmatic activity related to partial melting of an enriched lithospheric mantle together with crustal derived melts.In this paper,we present new whole rock geochemical analyses combined with zircon and titanite U–Pb and zircon Hf isotopic data from potassic to ultrapotassic rocks from six plutons that occur within the Archean Itacambira-Monte Azul block(BIMA),to discuss their petrogenesis and the tectonic implications for the São Francisco paleocontinent.The new U–Pb ages range from ca.2.06 Ga to 1.98 Ga and reveal long-lasting potassic magmatism within the BIMA,which is within the late-to-post-collisional stage of the São Francisco paleocontinent evolution.The ultrapotassic rocks are compatible with a fluid-related metasomatized mantle source enriched by previous subduction events,whereas the potassic rocks are bimodal and have a transitional shoshonitic to A-type affinity.These rocks have a hybrid nature,possible related to the mixing between the mafic potassic/ultrapotassic rocks and high temperature crustal melts of the Archean continental crust.Our results also show an increase of within-plate signature towards the younger potassic magmas.The participation of an important Archean crustal component in the genesis of these rocks is highlighted by the common and occasionally abundant occurrence of Archean inherited zircons.The Hf isotopic record shows that most of the zircon inheritance has dominantly subchondriticεHf(t)values,which fits a crustal reworking derivation from a similar Eo-to Paleoarchean precursor crust.However,the presence of juvenile 2.36 Ga zircon inheritance in an ultrapotassic sample reveal the existence of a hidden reservoir that is somewhat similar to the described for the Mineiro Belt in southern São Francisco paleocontinent.

Evolution of the 3.65-2.58 Ga Mairi Gneiss Complex,Brazil:Implications for growth of the continental crust in the São Francisco Craton

The composition and formation of the Earth’s primitive continental crust and mantle differentiation are key issues to understand and reconstruct the geodynamic terrestrial evolution,especially during the Archean.However,the scarcity of exposure to these rocks,the complexity of lithological relationships,and the high degree of superimposed deformation,especially with long-lived magmatism,make it difficult to study ancient rocks.Despite this complexity,exposures of the Archean Mairi Gneiss Complex basement unit in the São Francisco Craton offer important information about the evolution of South America’s primitive crust.Therefore,here we present field relationships,LA-ICP-SFMS zircon U-Pb ages,and LA-ICP-MCMS Lu-Hf isotope data for the recently identified Eoarchean to Neoarchean gneisses of the Mairi Complex.The Complex is composed of massive and banded gneisses with mafic members ranging from dioritic to tonalitic,and felsic members ranging from TTG(Tonalite-Trondhjemite-Granodiorite)to granitic composition.Our new data point to several magmatic episodes in the formation of the Mairi Gneiss Complex:Eoarchean(ca.3.65–3.60 Ga),early Paleoarchean(ca.3.55–3.52 Ga),middle-late Paleoarchean(ca.3.49–3.33 Ga)and Neoarchean(ca.2.74–2.58 Ga),with no records of Mesoarchean rocks.Lu-Hf data unveiled a progressive evolution of mantle differentiation and crustal recycling over time.In the Eoarchean,rocks are probably formed by the interaction between the pre-existing crust and juvenile contribution from chondritic to weakly depleted mantle sources,whereas mantle depletion played a role in the Paleoarchean,followed by greater differentiation of the crust with thickening and recycling in the middle–late Paleoarchean.A different stage of crustal growth and recycling dominated the Neoarchean,probably owing to the thickening of the continental crust by collision,continental arc growth,and mantle differentiation.

Neoarchean atmospheric chemistry and the preservation of S-MIF in sediments from the São Francisco Craton

Sulfur mass-independent fractionation(S-MIF)preserved in Archean sedimentary pyrite is interpreted to reflect atmospheric chemistry.Small ranges in Δ^(33)S that expanded into larger fractionations leading up to the Great Oxygenation Event(GOE;2.45–2.2 Ga)are disproportionately represented by sequences from the Kaapvaal and Pilbara Cratons.These patterns of S-MIF attenuation and enhancement may differ from the timing and magnitude of minor sulfur isotope fractionations reported from other cratons,thus obscuring local for global sulfur cycling dynamics.By expanding the Δ^(33)S record to include the relatively underrepresented São Francisco Craton in Brazil,we suggest that marine biogeochemistry affected S-MIF preservation prior to the GOE.In an early Neoarchean sequence(2763–2730 Ma)from the Rio das Velhas Greenstone Belt,we propose that low δ^(13)Corg(<-30‰)and dampened Δ^(33)S(-0.4‰to-0.7‰)in banded iron formation reflect the marine diagenetic process of anaerobic methane oxidation.The overlying black shale(TOC up to 7.8%)with higher δ^(13)Corg(-33.4‰to-19.2‰)and expanded Δ^(33)S(2.3‰±0.8‰),recorded oxidative sulfur cycling that resulted in enhance preservation of S-MIF input from atmospheric sources of elemental sulfur.The sequence culminates in a metasandstone,where concomitant changes to more uniform δCorg(-30‰to--25‰),potentially associated with the RuBisCO I enzyme,and near-zero Δ^(33)S(-0.04‰to 0.38‰)is mainly interpreted as evidence for local oxygen production.When placed in the context of other sequences worldwide,the Rio das Velhas helps differentiate the influences of global atmospheric chemistry and local marine diagenesis in Archean biogeochemical processes.Our data suggest that prokaryotic sulfur,iron,and methane cycles might have an underestimated role in pre-GOE sulfur minor isotope records.

Chemical-Abrasion U-Pb zircon geochronology reveals 150 Myr of partial melting events in the Archean crust of the São Francisco Craton

Field observations and CA-LA-ICP-MS U–Pb zircon ages and Hf isotope compositions obtained from migmatitic orthogneisses and granitoids from the Belo Horizonte Complex,southern São Francisco Craton,indicate a major period of partial melting and production of felsic rocks in the Neoarchean.Our observations show that the complex is an important site for studying partial melting processes of Archean crystalline crust.Much of the complex exposes fine-grained stromatic migmatites that are intruded by multiple leucogranitic veins and sheeted dikes.Both migmatites and leucogranite sheets are crosscut by several phases of granitoid batholiths and small granitic bodies;both of which are closely associated with the host banded gneisses.Chemical abrasion followed by detailed cathodoluminescence imaging revealed a wide variety of zircon textures that are consistent with a long-lived period of partial melting and crustal remobilization.Results of U-Pb and Hf isotopes disclose the complex as part of a much wider crustal segment,encompassing the entire southern part of the São Francisco Craton.Compilation of available U-Pb ages suggests that this crustal segment was consolidated sometime between 3000 Ma and 2900 Ma and that it experienced three main episodes of partial melting before stabilization at 2600 Ma.The partial melting episodes took place between 2750 Ma and 2600 Ma as a result of tectonic accretion and peeling off the lithospheric mantle and lower crust.This process is likely responsible for the emplacement of voluminous potassic granitoids across the entire São Francisco Craton.We believe that the partial melting of Meso-Archean crystalline crust and production of potassic granitoids are linked to a fundamental shift in the tectonics of the craton,which was also responsible for the widespread intrusion of large syenitic bodies in the northern part of the craton,and the construction of layered mafic–ultramafic intrusions to the south of the BHC.

The Paleoarchean Northern Mundo Novo Greenstone Belt,São Francisco Craton:Geochemistry,U-Pb-Hf-O in zircon and pyriteδ^(34)S-Δ^(33)S-Δ^(36)S signatures

Greenstone belts contain several clues about the evolutionary history of primitive Earth.Here,we describe the volcano-sedimentary rock association exposed along the eastern margin of the Gavião Block,named the Northern Mundo Novo Greenstone Belt(N-MNGB),and present data collected with different techniques,including U–Pb–Hf–O isotopes of zircon and multiple sulfur isotopes(^(32)S,^(33)S,^(34)S,and ^(36)S)of pyrite from this supracrustal sequence.A pillowed metabasalt situated in the upper section of the N-MNGB is 3337±25 Ma old and has zircon with ε_(Hf)(t)=2.47 to1.40,Hf model ages between 3.75 Ga and 3.82 Ga,and δ^(18)O=+3.6‰to+7.3‰.These isotopic data,together with compiled whole-rock trace element data,suggest that the mafic metavolcanic rocks formed in a subduction-related setting,likely a back-arc basin juxtaposed to a continental arc.In this context,the magma interacted with older Eoarchean crustal components from the Gavião Block.Detrital zircons from the overlying quartzites of the Jacobina Group are sourced from Paleoarchean rocks,in accordance with previous studies,yielding a maximum depositional age of 3353±22 Ma.These detrital zircons have ε_(Hf)(t)=5.40 to0.84,Hf model ages between 3.66 Ga and 4.30 Ga,and δ^(18)O=+4.8‰to+6.4‰.The pyrite multiple sulfur isotope investigation of the 3.3 Ga supracrustal rocks from the N-MNGB enabled a further understanding of Paleoarchean sulfur cycling.The samples have diverse isotopic compositions that indicate sulfur sourced from distinct reservoirs.Significantly,they preserve the signal of the anoxic Archean atmosphere,expressed by MIF-S signatures(Δ^(33)S between1.3‰to+1.4‰)and a Δ^(36)S/Δ^(33)S slope of0.81 that is indistinguishable from the so-called Archean array.A BIF sample has a magmatic origin of sulfur,as indicated by the limited Δ^(34)S range(0 to+2‰),Δ^(33)S~0‰,and Δ^(36)S~0‰.A carbonaceous schist shows positive Δ^(34)S(2.1‰–3.5‰)and elevated Δ^(33)S(1.2‰–1.4‰)values,with corresponding negative Δ^(36)S between1.2‰to0.2‰,which resemble the isotopic composition of Archean black shales and suggest a source from the photolytic reduction of elemental sulfur.The pillowed metabasalt displays heterogeneous Δ^(34)S,Δ^(33)S,and Δ^(36)S signatures that reflect assimilation of both magmatic sulfur and photolytic sulfate during hydrothermal seafloor alteration.Lastly,pyrite in a massive sulfide lens is isotopically similar to barite of several Paleoarchean deposits worldwide,which might indicate mass dependent sulfur processing from a global and well-mixed sulfate reservoir at this time.

Archean-Ediacaran evolution of the Campos Gerais Domain-A reworked margin of the São Francisco paleocontinent(SE Brazil):Constraints from metamafic-ultramafic rocks

The Campos Gerais Domain(CGD)in southeastern Brazil is an approximately 180 km×35 km area of Archean–Proterozoic rocks located southwest of the São Francisco Craton(SFC).The Archean–Paleopro terozoic evolution of the CGD—alongside its potential correlation with the SFC or other cratonic blocks in the region-is currently poorly-constrained.We present the results of systematic petrography,bulkrock geochemistry,mineral chemistry and geochronology for a suite of scarcely studied mafic–ultramafic rocks from the CGD.We also provide a compilation of previously reported bulk-rock geochemical and spinel group mineral chemical data for mafic–ultramafic rocks throughout the CGD,and geochronological information for various lithotypes in the region.The CGD records a protracted Mesoarchean to Statherian(3.1–1.7 Ga)crustal evolution,which we interpret to share a common history with the southern SFC and their related reworked segments,suggesting that it is a westward extension of this cratonic terrain.The metavolcano-sedimentary rocks of the Fortaleza de Minas and Alpinópolis segments represent a Mesoarchean greenstone belt that is stratigraphically and chemically comparable to Archean greenstone belts worldwide,and that is broadly coeval with a local suite of tonalite-trondhjemite-grano diorite(TTG)gneisses and migmatites.U-Pb SHRIMP zircon data from a subalkaline metagabbro yielded a concordia age of ca.2.96 Ga,revealing a previously unrecognized phase of Archean magmatism in the CGD that can be chrono-correlated with metakomatiite and TTG generation elsewhere in the São Francisco paleocontinent.Our data contradict a hypothesis whereby the metavolcano-sedimentary rocks of the Jacuí-Bom Jesus da Penha and Petúnia segments represent an ophiolite,as previously suggested,instead presenting features that point to formation in association with a continental arc.Coupled with a U-Pb(SHRIMP)crystallization age of ca.2.13 Ga recorded by zircon grains from a metaultramafic rock,these data highlight that a magmatic event was chrono-correlated with the main accretionary phase of the Minas Orogeny,and with the Pouso Alegre/Amparo and São Vicente complexes.Finally,a U-Pb(SHRIMP)concordia age of ca.590 Ma—obtained from metamorphic-textured zircon grains from a metaultramafic rock—points to a late metamorphic overprint related to upper amphibolite conditions,brittle fault activation and the juxtaposition of crustal blocks in association with the latest stages of western Gondwana’s assembly in the southern SFC,with later retrogression to greenschist-facies.

More Erratic and More Extreme: Trends in Precipitation in the State of São Paulo, Brazil

The study assessed changes in rainfall variability and the frequency of extreme events (very wet and very dry) in the state of S?o Paulo, Brazil, for a 40-year period that divided into two sub-groups: 1973-1992 (P1) and 1993-2012 (P2). Data of 79 rain gauge stations were selected to represent the different climatic and geomorphological domains of the state. The annual pattern was evaluated through the scale and the shape parameters of the gamma distribution and the 95th and the 5th percentiles thresholds, the latter also employed to evaluate the seasonal spatial patterns (rainy season, Oct.-Mar. and sub-humid to dry season, Apr.-Sep.). Results showed that the average precipitation was similar in P1 and P2, but S?o Paulo evolved to a pattern of increased irregularity in the rainfall distribution, with a rise of approximately 10% in the number of extremes between 1973 and 2012, especially in the very dry occurrences, and in the north and west of the state, which are the least rainy regions. Moreover, while 55% of the evaluated rain gauges recorded more extreme wet episodes in P2, 76% registered more dry extreme episodes in the same period. Some very dry or very wet events recorded after the 40-year period evaluated were discussed in terms of the associated weather patterns and their impacts on society and attested to the validity of the results found in the quantitative assessment. The qualitative analysis indicates that if the trends of more irregular distribution of rain and increase in extreme events persist, as pointed out by the gamma and percentile analyses, they would continue to bring serious effects on the natural and social systems in the state, which is the most populous and has the strongest and most diversified economy in Brazil.

Anthropogenic impacts to the sediment budget of São Francisco River navigation channel using SWAT

The São Francisco River Basin,located in eastern Brazil,has undergone a significant amount of anthropogenic changes in the last several decades,such as agricultural expansion,irrigation activities,mining,and the construction of large dams.Together,these changes have altered the historic sediment budget and have led to an aggradation of sediments in the navigation channel,impacting the ability to efficiently ship agricultural commodities to regional ports.In an effort to aid decision makers in future waterway navigation planning,an international partnership between the Brazilian government agency CODEVASF and the US Army Corps of Engineers(USACE)was created.Through this partnership a SWAT model of the 630000 km2 São Francisco River basin was developed to better understand both the historic and current sediment budget within the navigation channel.The SWAT model of the São Francisco River Basin was calibrated for hydrology and sediment loads.Monthly discharges were calibrated at 17 Agência Nacional deÁguas(ANA)gages,with Nash-Sutcliffe efficiency(NSE)values ranging from 0.42 to 0.75 for an eleven year simulation.Sediment loads were calibrated to an ANA sediment gage located in the Middle São Francisco River Navigation Channel,with a PBIAS(Percent Bias)of 11.6.Based on model results,the aggradation rate of sediment in the São Francisco River and major tributaries has increased by approximately 20 Mt since Pre-European settlement of the basin(from approximately 7 Mt/a to 27 Mt/a).This increase has contributed to an impaired navigation channel due to shoaling of sandy sediments in the navigation channel.

Restoration as a Social Cohesion Instrument:Vila Itororóin Central São Paulo

Recently,the restoration work of Vila Itororó-an architectural complex in central São Paulo,built around the 1920s,has been carried out,enabling applied field research for restoration as well as for historical per­spective of the social and cultural development that took place at Vila Itororó.Alongside the restoration work,a cultural centre has been installed on the site,embracing the opportunities of creating a new agenda for Vila Itororówith the community while the restoration takes place.Through this,Vila Itororóhas been able to bring the discus­sion and practise of restoration closer to the civil society,reaching a public beyond the academic circles.The rich environment produced by these efforts has allowed for an outlet of publications and discussions regarding issues that range from architectural prospection to the role that heritage can play with our society in the city of the 21st century.This paper intends to present some of these discussions,their origins,insights and other findings that this experience has fostered.

U-Pb provenance fingerprints of metavolcanic-sedimentary successions of the Mineiro belt:Proxies for the continuity of plate tectonics through the Paleoproterozoic

We document new U-Pb detrital zircon LA-MC-ICP-MS data for seven metavolcanic-sedimentary successions and metasedimentary sequences and reassess additional dates of five siliciclastic samples toward their tectonic significance in the context of the Mineiro belt,Southern São Francisco Craton.This belt represents a crustal segment of the 2.47–2.00 Ga Minas Orogen,classically known by its Siderian and Rhyacian juvenile rocks with important implications in the Earth’s geodynamics.The new and compiled detrital provenance constraints unravel the long-lived magmatic and sedimentary history of the studied basins,lasting ca.230–220 Myr.The maximum depositional dates around 2.1 Ga reflect the renewed sediment budget with the subsequent metamorphic episode ca.2.0 Ga.Most of the unmixed relative probability diagrams are consistent with sourcing from the Siderian and Rhyacian arcs of the Mineiro belt,determining a detrital provenance change in time and space for the precursor basins.Alternative potential sources could be the youngest rocks of the Mantiqueira and Juiz de Fora terranes that constitute the other segments of the Minas Orogen,given the age match.The overall detrital fingerprints determine the study basins resumed mainly in Rhyacian fore-arc and/or back-arc settings,i.e.,akin to a subductionrelated system that evolved to a collisional(foreland)environment.Few samples show fingerprints of primary extensional settings,determined by major Archean detrital populations sourced from areas outside the Mineiro belt beside the Paleoproterozoic detritus.The working model considers the collage between the Mineiro belt and the ancient foreland around 2.10 Ga and eventual interaction with other crustal segments of the Minas Orogen,generating the ca.2.0 Ga metamorphism over the metasedimentary samples.The more complete isotopic repository in detrital and igneous zircon grains for the studied supracrustal successions and the associated rocks allows new insights into the Rhyacian–Orosirian dynamics of the Minas orogeny.In a broader perspective,the juvenile nature of the Mineiro belt reinforces the paradigm of uninterrupted continental growth during the Paleoproterozoic Earth.

Rhyacian-Orosirian tectonic history of the Juiz de Fora Complex:Evidence for an Archean crustal reservoir within an island-arc system

The southern São Francisco Paleocontinent(SFP)comprises Archean nuclei and Paleoproterozoic complexes encompassing magmatic arcs juxtaposed during a Rhyacian to Orosirian orogenic event.The Juiz de Fora Complex(JFC)represents an imbricated thrust system that comprises orthogranulites with a wide compositional range formed in an intra-oceanic setting during the Siderian to the Orosirian and later accreted to the southeastern margin of the SFP.Here we report new petrological,geochemical,whole-rock Nd and Sr data,as well as zircon U–Pb ages from felsic and mafic orthogranulites from the JFC.The new data is combined with a regional compilation that enables an evaluation of the interaction between magmatism and orogenetic episodes in the context of the consolidation of São Francisco Paleocontinent during the Rhyacian–Orosirian.Pre collisional Island Arc tholeiites(IAT),Tonalites-Tron dhjemites-Granodiorites(TTGs)and sanukitoid magmatism occurred from 2200 Ma to 2085 Ma.This was followed by post-collisional magmatism,which is represented by hybrid granitoids coeval with the emplacement of E-MORB basic rocks.Crustal signatures for the Rhyacian to Orosirian evolution are highlighted by the dominance of negativeεNd(t)associated with Meso-to Neoarchean Nd TDMmodel ages as well as inherited zircon grains from the hybrid granitoids.The JFC is extensively highlighted in the literature as a primitive intra-oceanic arc,but here we propose the reworking or recycling of ancient crustal segments within the mature arc stage of the JFC,suggesting a Mesoarchean crustal source involved in the JFC evolution.

Acute Hemorrhagic Fever: Clinical, Epidemiological and Laboratory Aspects in São Toméand Príncipe

Background: In the last 6 months, cases of acute hemorrhagic fever (AHF) have been recorded in Sao Tome and Principe (STP). Objective: To identify the clinical, epidemiological and laboratory parameters associated with AHF cases found in patients hospitalized in STP. Methods: Descriptive and quantitative analysis of AHF cases hospitalized in STP in the period December 2021 to May 19, 2022 through the variables: demographic data;clinical data;laboratory data and clinical outcome. Results: Analyzed 18 of 22 AHF cases, 50% of them male, mean age 33.7 years, 85.7% residing in the 2 largest districts of the country, 66.7% rural workers, administrative near maritime areas, sailors and domestics. 66.7% were healthy individuals. ≥50% had a fever, asthenia/weakness, myalgia, headache, lethargy, nausea, vomiting, and diarrhea. 22.2% to 33.3% had retro-orbital pain, abdominal pain, decreased consciousness, dyspnea/hypoxia, and cough. In a smaller register (5.6% - 11.1%), exanthema, convulsion, arthralgia, low back pain, chills, and chest pain. Bleeding from the digestive tract was found in 72.2%, followed by vaginal (33.3%), urethral (27.8%), nasal (22.2%), and oral (16.7%). 50% had laboratory confirmation for dengue, and another 50% with suspected clinical diagnosis without laboratory confirmation of the etiologic agent. Despite hemorrhage, 66.7% of confirmed cases were hemodynamically non-severe, and 88.9% of suspected cases were severe. Coinfection with malaria is evidenced in 11.1% of cases. 72.2% recovered and 27.8% died (deaths in 55.5% of suspected cases). Case deaths were male (100%), resident foreigners (40%), tool store employees, sailors and students, healthy (80%), and residing in the largest district in the country (60%). All deaths were hospitalized in serious condition, 80% were hospitalized for hemorrhage and shock, with bleeding arising between day 4 - 5 of illness in 60% and hospitalization on day 5 of illness. 60% died within ≤24 hours of hospitalization. 80% died from shock and multi-organ dysfunction and 20% from respiratory failure. Deaths had thrombocytopenia (100%), renal dysfunction (100%) and significantly increased transaminases (100%), anemia (75%) and leukocytosis (66.7%). 20% had a radiological change of pulmonary infiltrates. Conclusion: Our data reveal the complexity of the pathogens causing AHF and suggest the possible presence of other human pathogens usually unknown in the Santomean geographical territory.

巴西圣弗朗西斯科克拉通地质演化与重要成矿作用

【研究目的】本文旨在梳理构建巴西圣弗朗西斯科克拉通构造演化过程,概述与之成矿作用地质背景及矿床成矿系列的耦合关系,并查明典型矿床的时空分布,目的是服务于克拉通演化与成矿理论。【研究方法】本文在中巴合作开展野外地质调查的基础上,结合巴西圣弗朗西斯科克拉通基底太古宙片麻岩和元古代的碎屑岩锆石U-Pb、Sm-Nd同位素年代学等文献资料,初步归纳出圣弗朗西斯科克拉通重大地质构造演化事件和重要成矿作用。【研究结果】圣弗朗西斯科克拉通4个重要地质演化过程:(1)太古宙3.5 Ga前克拉通古陆核与微陆块形成,3.3~2.9 Ga和2.8~2.5 Ga间则由克拉通北区的盖维奥、索布拉迪纽、塞里尼亚和吉基耶等4个古陆核及南区的近圆形古陆核相互碰撞、拼合和绿岩-增生造山岩浆作用而形成稳定的克拉通陆块;(2)2.5~1.9 Ga古元古代泛亚马逊造山岩浆作用;(3)1.78~1.20 Ga克拉通基底隆升与裂谷改造阶段,形成大量基性岩墙群及陆内非造山型岩浆,完成陆块增厚和最终克拉通化;(4)新元古代克拉通边缘经历巴西利亚/泛非运动(0.64~0.54 Ga)改造,又形成巴西利亚等6个活动造山带。圣弗朗西斯科克拉通形成4期重要成矿作用及相应矿床成矿系列:(1)太古宙(2.5 Ga前)形成绿岩型金矿、苏必利尔湖型硅铁建造为主的变质火山-沉积矿床等成矿系列;(2)古元古代早中期(2.5~1.8 Ga)形成与(超)基性岩相关的铜镍钴硫化物矿床、VMS型铅锌银矿床、IOCG等系列矿床;(3)固结纪-中元古代(1.8~1.0 Ga)形成与非造山岩浆作用相关的铌钽矿、铀矿床,与陆内(缘)裂谷型的钒-钛-铁矿床等系列;(4)新元古代(1.0~0.54 Ga)主要形成铁锰矿、砂锡矿及磷矿等矿床,包括古陆缘-浅海沉积环境有关的(冲积)金刚石砂矿等系列矿床。【结论】构建了巴西圣弗朗西斯科克拉通4个重要地质演化过程,相应划分出4期重要成矿作用。

Analyzing the economic viability of a large-scale integrated model of municipal solid waste:a study case for the most important Brazilian economic region

Despite the National Policy for Solid Waste(PNRS)in 2010,nothing has changed to waste disposal in Brazil.Planned to reach 100%of all Municipal Solid Waste(MSW)collected and treated in landfills by Aug.2nd,2014,until nowadays,42%of this total remains in dumps.Even the most important national economic region treating its urban waste in landfills,what it has is no more than 4%of recycling and its landfills reaching the exhaustion.Building other ones is getting harder year by year,due to water reservoirs around the region,high freight costs,waste disposal and the severe control of emissions associated with its logistics.This article comes to break the paradigm of investment and profitability proposing an alternative to the land-use,achieving higher rates of recovering.The economic viability,carried out through well-known financial variables and Monte Carlo analysis,has taken into account proven local waste characteristics and market prices for recyclables and energy without subsidies.Even considered a proposal highly intensive in capital and people,the revenues from the sales would be enough to guarantee the viability of 100%equity with IRR of 33.7%and ROI of 24.5%per year within the confidence of 99%.

开辟拓殖地与日本在巴西的早期移民活动

购买土地、开垦荒地和创建拓殖地是日本在巴西早期移民活动的一大亮点。为了获得更大的经营自主权和更多的经济收益,在履行完劳动契约后,一部分日本移民离开种植园,在圣保罗市郊、西北铁路沿线等地购买土地开辟拓殖地。最早的拓殖购地行为大多是移民迫于生计、零散的和自发的个体行为。而后,伊瓜佩地区的拓殖地则是由日本政府推动的、有组织的官商合办行为,兼具投资、置地和移民三重作用。