geologia e recursos minerais da folha eldorado paulista sg ... - CPRM

Geologia e Recursos Minerais da Folha Eldorado Paulista
ABSTRACT
The Eldorado Paulista Sheet (SG.22-X-B-VI) comprises part of the states of São Paulo
and Paraná, southeastern Brazil. It is bounded by longitudes 48 o 30’W and 48 o 00’W
and latitudes 24 o 30’S and 25 o 00’S. Geologic mapping at 1:100,000 scale allowed
for a substantive reformulation of the regional stratigraphy with refinement of
previously defined units and mapping of new units. The geolocial units are related
with the terranes (or tectonic domains) Apiaí, Curitiba, Paranaguá and Luís Alves.
The first three are segments of the southeastern Ribeira Belt (Mantiqueira Province),
while the latter represents a cratonic fragment did not affect by the Brasiliano-Pan
African Orogeny.
The Apiaí Terrane is dominated by supracrustal rock sequences including
metavolcanosedimentary and metasedimentary rock units metamorphosed
under lower greenschist to amphibolite facies conditions included in the Açungui
Supergroup, considered as a composite terrane. The Açungui Supergroup is divided
into two units, with internal subdivisions: (i) the Votuverava Group (ca. 1450-1480
Ma), composed of rhythmic metapelites (slate and phyllite) with intercalations of
basic metavolcanic rocks, lenses of quartzite and calc-silicated rocks, subdivided
into the Nhunguara, the Piririca, the Rubuquara and the Ribeirão das Pedras
formations; (ii) the Serra das Andorinhas Sequence (Calymmian?), composed of
rhythmic phyllite and micaschist, marble and calc-silicatic rocks, subdivided into a
metapelitic unit and the Tapagem Marble.
The Curitiba Terrane is composed of basement rocks of the Barra do Azeite Banded
Gneiss (Atuba Complex) and supracrustal sequences of the Capiru and Turvo-Cajati
formations. The Barra do Azeite Banded Gneiss (ca. 2200-2100 Ma) is composed
of banded orthogneiss migmatized under upper amphibolite facies conditions and
mylonitized under greenschist facies conditions. The Capiru Formation, maximum
age of sedimentation of ca. 800-850 Ma, is composed of siliciclastic and carbonate
metasedimentary rocks, metamorphosed under lower greenschist facies conditions.
The Turvo-Cajati Formation, with maximum age of sedimentation of ca. 850-900 Ma,
is composed of siliciclastic and carbonate metasedimentary rocks metamorphosed
under greenschist to granulite facies conditions. It is subdivided into a phyllite unit
(rhythmic phyllite and slate – metasiltstone, meta-argillite and metasandstone),
a micaschist unit (coarse-grained micaschist with garnet and locally staurolite
and kyanite) and a paragneiss unit (sillimanite-garnet paragneiss, coarse-grained
anatetic micaschist and locally kyanite-garnet paragneiss). The Curitiba Terrane
also includes two volcanosedimentary basins of Proterozoic-Fanerozoic transition,
related with shear zones (Indaiatuba and Quatis formations).
The Luís Alves Terrane is formed by the Serra Negra Complex, of Archean to
Paleoproterozoic age, the oldest unit of the Eldorado Paulista Sheet, and by
supracrustal rocks of the Rio das Minas Formation. The Serra Negra Complex is
composed primarily of gneissic-granulitic rocks of basic to intermediate composition
(gabbroids, tonalite, granodiorite) preserved or partially retrometamorphosed
under upper greenschist to amphibolite facies conditions. The Rio das Minas
Formation (redefinition of the Cachoeira Sequence) is composed of siliciclastic
metasedimentary rocks metamorphosed under lower greenschist to upper
amphibolite facies conditions. It is subdivided into a unit of slate and phyllite,
a micaschist unit and a paragneiss unit. The presence of lenses of ultramafic
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