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Neoarqueano e aquele do Paleoproterozóico. Adicionalmente, a anomalia negatíva de Nb da suíte básico norítica (2,65 Ga), sugere que o manto litosférico no Neoarqueano possa ter sido fertilizado através de um prÕcesso de subducção envolvendo crosta oceânica e/ou sedimentos terrigenos continentais.Cornparações isotópicas e geoquímìcas dos diques de Lavras com outros enxanìes de diques no âmbito do C¡áton do São Francisco revelam que a suite básica (l,9 Ga) apresenta similaridades composicionais com o enxame de Uauá (Bahia), entre outros. sugerindo um possível manto subcontinental geoquimrcamente similar em diferentes porçòes do segmento cratônico. Tectonicamente, os diques da suíte básico norítica (2 658 Ma) intrudiram a crosta continental sob r-egime extensional apcis o l.ivento Rio das velhas (2.780-2 700 Ma). ilustrando os processos finais de estabilização do Complexo Campo llelo. Os diques cla s'rite básica (1.875 Ma), teriam se colocado durante a tectônica extensional associada aos estágios finais cla orogenia transamazônica, responsável pelo desenvolvimenlo do Arco Magrnático Mineiro. VI ABSTRACT At least t\¡ro ltrecatnbrian mafic dyke swarms are located in Lavrasllom Sucesso region in the southern part of São Francisco Craton (Minas Gerais State, Brazil). Such dykes are intrusive into Archean rocks of the Campo Belo Complex (27 90 -2660 Ma) that \ /ere reworked in the Paleoprot erozoic (2140 -1980 Ma) and some of them intruded the supraorustals of the Minas Supergroup. T'he clykes trend preferably N400-600W, N200-4008, N-S and subordinantly N100-300W, N500-7008, B-W orientations, and those oriented N4O0-600W are the tickest (untit 100 m) and the longest dykes (untrl 30 Km).Petrographic studies and field data suppofi the subdivision of the dykes in the followrng groups: l)basic-noritic dykes (BND); 2) basic dykos I (BD¡); 3) basic dykes 2 (BDr); a) metabasic dykes (Mì3D); 5) amphrbolitíc dykes (AD). The IlDr has similar mineralogical composition (e.g. biotite accessory and bronzite) when compared to the ÈiND.Geochemical data show that the BD r and BND belong to a same group named basic-noritic suite. the former being the more evolved member in the suite. On the other irand, llD2 is compositionally different f¡om this suite and rs named basic suite. The basic suite dykes are predominantly tholeiitic basalts while the basic-noritic suite oomprises tholeirtic basalts and {holeiitic andesi-basalts. The cliemical similarities and Rb-Sr isotope data suggest that the rr.retamor¡rhic dykes (MBD and AD) ale related to the basic suite evolutior.l.Major and lrace elements tevcal significant compositional varialtons between thesc two dvke suites The basic-noritic suite displays higher corrtents of SiOz (55 vs 5l%), KrO (1 2 vs 0 59'6), Rb (40 vs l0 ppm), Sr (225 vs I40 ppm). Ba (300 vs 90 ppm) tl.ran those from tlie l¡asjc surte. Lrased on sir-nilar mg/l values [(Mg''?/Mg '?r-¡e':) to [re2O1/feg "' O.l5l. Basic-noritic and basic suites are distinct in telms of ZrlBa, Zr/Ce and Zrll{b ratios. 'l-he basic-noflt...

Nb spikes. They have variable e t (Nd) values (−0•5 to 12•1), regions) is characterized by Early Proterozoic (2•0 Ga) calcwhich mainly reflect derivation from a depleted source mantle. alkaline and Middle Proterozoic (1•6 Ga) tholeiitic dyke swarms High-TiO 2 tholeiitic dykes have more enriched IE-PM patterns intruding the crystalline basement involved in the Transamazonian and are characterized by e t (Nd) values (−1•4 to −7•5 ) typical Orogeny (2•2-1•9 Ga). The calc-alkaline dykes have andesitic of an enriched source mantle. Chemical and isotopic data and and rhyolitic compositions and trend east-west, whereas the melting modelling indicate that both calc-alkaline and tholeiitic tholeiitic dykes mainly trend N30°W and are represented by dykes originated by different melting degrees of a heterogeneous basalts with low (0•9-1•7 wt %) and high TiO 2 (up to source mantle, the variable IE enrichment of which may have 3•7 wt %). The calc-alkaline dykes have primitive mantle occurred in Late Archaean to Early Proterozoic times. The emplacement of the calc-alkaline dykes is associated with the (PM)-normalized trace element patterns enriched inRb, Ba, K, La, Ce and Nd, and significant negative Nb and Ti transtensional stage of the Transamazonian Orogeny, whereas the tholeiitic dykes reflect extensional tectonics succeeding the anomalies. These dykes are characterized by e t (Nd) values of −3 to −4, similar to those of the EMI mantle component. Transamazonian event. The calc-alkaline and tholeiitic dykes are similar in emplacement age and characteristics to meta-Low-TiO 2 tholeiitic dykes have low incompatible-element (IE) contents and PM-IE patterns with slightly positive or negative morphosed granites and volcanic rocks outcropping within the

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The contamination of soils by metals issuing from municipal solid waste (MSW) disposal in tropical environments has hardly been studied with regard to the particular problems associated with them, i.e., generally a high permeability of soils despite the abundance of clay, and the role of reactive Fe compounds. From a previous geotechnical and chemical survey, three latosol profiles differently affected by MSW leachates in the region of Londrina (Paraná, Brazil) were selected. The aims were to evaluate the extent of their contamination, to better understand the fate of potentially harmful metals in tropical soils and rank the determining factors. Samples between 0.5 and 7 m depth were analyzed for their physical, mineralogical and chemical properties, and their micro-morphology was described by optical and transmission electron microscopy. Two steps of a sequential extraction procedure helped to assess the mobility of elements and to better discriminate between metals originating from pedogenesis and issued from MSW. These combined approaches showed that exposed soil profiles have been impacted at various depths, down to 7 m, through increased metal content, especially enhanced mobility of Zn, Co, Mn, Cu and Fe, and through increased salinity and organic matter. The mobility of potentially harmful metals should decrease with pH, which significantly increased in some impacted horizons, but other factors can reverse this trend.

This paper presents the results of an ex-post assessment of two important dams in Brazil. The study follows the principles of Social Impact Management, which offer a suitable framework for analyzing the complex social transformations triggered by hydroelectric dams. In the implementation of this approach, participative causal maps were used to identify the ex-post social impacts of the Porto Primavera and Rosana dams on the community of Porto Rico, located along the High Paraná River. We found that in the operation of dams there are intermediate causes of a political nature, stemming from decisions based on values and interests not determined by neutral, exclusively technical reasons; and this insight opens up an area of action for managing the negative impacts of dams.

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