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A sample of the Crixás-Açu gneiss in Central Brazil contains protolith and metamorphic zircons, and two generations of metamorphic titanite. SHRIMP U-Pb data of these different mineral generations indicate the following temporal sequence: tonalitic magmatism at 2817 ± 9 M.y derived from an older source region (3050 to 2930 M.y zircon cores); Archaean metamorphism at 2772 ± 6 M.y (from zircon) with cooling to the blocking temperature of titanite (at 2711 ± 34 Ma); followed by Palaeoproterozoic metamorphism and weak fabric development at 2011 ± 15 Ma, and a possible Neoproterozoic metamorphism. The field relations and these age data indicate the polymetamorphic history of the area and demonstrate the value of in situ age determinations on well-characterized rocks.

Thi s paper pre sent s the results of geologicalma pping undertaken in the C hapada-C um pinon c regio n. nort hwe ste rn pan of the 'loc nnrins Pro vince. w hic h co mprises rock s o f the A rc haea n Hid rolina Co m plex. the Paleoproremzic C a m pino rte volcan o-sedi men tary Se q uence. Mesopnucruzoic met asedimen ts fro m the Serra da Mesa Group a nd Neoproterozoic suprac rus ta l rock s from the Ma ra Rosa Volcano-sedimentary Se q ue nce. Th ese lithol ogies were affected by pre-Brasiliun o dctomuuion. as a cons eq uen ce of north-so uth com pression. fo llowed by thc Hrnsilinuo orogen e sis. Geo c hemical and geochronolog ical S l11/N d data iudic utc that the C rnupinortc Vo lcano-sedim entary SC(]lICI1t:C was gen erated in an islan d-arc e nvironmen t du ring the Palcoprotcrozoic. Thi s geo log ic envinnun e nt. a nd its d ose assoc iatio n with the Golas Mag mati c A rt: (M ara Rosa Volcan oscdimeuuu'y Sequence) suggest a tec to no-met amorphic geo log ic evolutio n invol ving amalgama tio n du e to the A ma zo nia n and Sao Fran cisco cnuons converge nce. Gold min eraliza tions in the C am piuonc Volcano-sedimen tary Sequence arc hosted by quart z ve ins controlle d by NS strike-slip faults and cl ose ly associated to magn etit e-rich g ranite s a nd d iorites.

The Goiás Magmatic Arc hosts several gold and copper-gold deposits, which were originated during several stages of the tectonic, magmatic and metamorphic evolution of this Neoproterozoic Arc, between ca. 0.9 and 0.6 Ga. The nature of these deposits, their spatial distribution, and timing of mineralization agree with the model involving the continuous evolution of a collisional belt. They also display some of the characteristics of the orogenic gold deposits. The Zacarias Au-Ag-Ba Deposit was originated by volcano-exhalative processes in an intraoceanic subduction setting, whereas the Chapada Cu-Au Deposit (porphyry copper-type mineralization) is connected with plutonic rocks also associated with an intra-oceanic arc. The Posse Au Deposit was formed during the syn-collisional phase, shortly following the metamorphic peak of the Brasiliano Orogeny (ca. 630 Ma). Finally, the genesis of the Mundinho Au-Cu-Bi Mineralization is related with the emplacement of granite intrusions associated with post-orogenic extension.

REMOTESENSING IMAGE LINEAMENTS AND THEIR STRUCTURAL SIGNIFICANCE IN THE CRIXÁS GII,ANITE-GREENSTON E BELT TERRANE (GO) This papel presents the results of the interpretation of lineaments from threedifferent remote sensing images (SLAR-GEMS 1000, TM-LANDSAT añ¿ S¡.if-¡eRS-l) applied to the Clixás gmnite-greenstone be]t^tefl'ane, Central Brazil. Two main lineãment systems are identified. One is a N30"Vy'-N30"E pair intepìeted as related to a Palaeoploterozoic deforlnation. The other is a N50('WN70nE pair-that cuts the former and is interpreted as lelated to a Ñeoproterozoic defoltnation (Brasiliano Cycle). The images fi'om different sensols provides a more complete observation of relief patterns and associated structures and a better ftamework of tl.re regional linealneut geometry, but their kinematics is only provided by data from outcrops.

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