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• Geochronology of LIP-scale events through time and space in the Amazonian Craton. • 1.89–1.87 Ga Uatumã SLIP links well the known LIP events on other crustal blocks. • 1.11 Ga LIP has remarkable match with intraplate activity in other places around the world. • 0.53 Ga dykes mark reactivation of the cratonic margin during West Gondwana assembly. • Ca. 200 Ma dykes correlate with the span of ages for CAMP LIP event. U-Pb baddeleyite ages for key mafic dykes of the Amazonian Craton reveal four significant intraplate episodes that allow connections with global igneous activity through time and supercontinent cycles. The oldest dykes (Carajás-Rio Maria region) are diabases with ages of 1880.2 ± 1.5 Ma and 1884.6 ± 1.6 Ma, respectively, corresponding with the Tucumã swarm which crops out to the west and is age-equivalent. The magmatic activity has a genetic link with the ca. 1.88 Ga Uatumã Silicic Large Igneous Province (SLIP), characterized by felsic plutonic-volcanic rocks. There is an age correlation with LIP events (ca. 1880 Ma) in the Superior, Slave, Indian and other cratons. This magmatism could be derived from significant perturbations of the upper mantle during the partial assembly of Columbia. Gabbronorite of the Rio Perdido Suite (Rio Apa Terrane) crystallized at 1110.7 ± 1.4 Ma, and is identical to that of the Rincón del Tigre-Huanchaca LIP event of the Amazonian Craton. This event was synchronous with the initiation of Keweenawan magmatism of central Laurentia (Midcontinent Rift) and also with coeval units in the Kalahari, Congo and India cratons. The two youngest U-Pb dates (535 and 200 Ma) occur in the Carajás region. Diabase of the Paraupebas swarm yields an age of 535.1 ± 1.1 Ma, which may be correlative with the giant Piranhas swarm located ca. 900 km apart to the west. The Paraupebas swarm is correlative with post-collisional plutonism within the Araguaia marginal belt. Therefore, the Cambrian dykes may reflect reactivation of cooled lithosphere, due to crustal extension/transtension active along the craton's margin during assembly of West Gondwana. This magmatism is also contemporaneous with the 539–530 Ma Wichita LIP of southern Laurentia. The youngest studied Carajás region dyke was emplaced at ca. 200 Ma, corresponding with 40Ar/39Ar ages for the Periquito dykes west of Carajás and with most K-Ar ages of the giant Cassiporé swarm, located north of the study area. The newly dated ca. 200 Ma dyke fits well into the known, brief span of ages for the CAMP Large Igneous Province event, around the present central and northern Atlantic Ocean. [ABSTRACT FROM AUTHOR]

We present new and compiled U–Pb zircon ages and Hf zircon and Nd constraints for rocks of the Bolivian Precambrian Shield southwestern fringe of the Amazonian Craton. The database and updated geologic information provide new insights into the Orosirian-Early Stenian evolution. This shield can be subdivided into the San Diablo and Paraguá domains considering their particular geologic histories and lithostratigraphic units: i) the southern San Diablo Domain consists mainly of amphibolite facies gneissic rocks with documented ages as old as 1940 Ma, intruded by the Correreca, Santo Corazón, Tauca, and Santa Terezita plutons with documented ages between 1874 and 1849 Ma; ii) the Paraguá Domain comprises the Lomas Maneches Granulite Complex (1820 Ma), the Chiquitania meta igneous-sedimentary complex (1750-1690 Ma), and the roughly coeval San Ignacio Schist Group (1690 Ma). Locally, the country rocks are crosscut by the Yarituses Suite (1683-1610 Ma), which is contemporary with the Lomas Maneches Granitoid Suite (1690-1660 Ma). The Pensamiento Granitoid Complex (1440-1270 Ma), constituted by syn-to late-kinematic and late-to post-kinematic granites, collectively known as San Ignacio Granitoids, is widespread in the studied region. Six zircon U–Pb datings and 76 compiled data determine that the continental crust experienced a long-lived tectonic-magmatic history, distinguished by three accretionary events: 1941–1849 Ma, 1690-1610 Ma, and 1430-1340 Ma. These events have relationships with the Proterozoic growth of Amazonia enclosing the distal Rio Apa Terrane. Later, the southern portion of the Bolivian Precambrian Shield experienced crustal shortening, magmatism, and overprints due to the Sunsás/Greenville (1200-1000 Ma) orogeny that marks the Amazonia-eastern Laurentia collage in Rodinia times. From a petrogenetic perspective, the country rocks of the San Diablo Domain yield documented Sm–Nd T DM ages and ε NdT values of ca. 1.69 to 2.29 Ga and −5.7 to +1.8 respectively, suggestive of the derivation of short-lived protoliths. The Correreca intrusion (1874–1862 Ma) gives published zircon Hf model ages of 2.68 Ga and 2.29 Ga and coupled ε HfT values of −4.6 to +2.8. The bulk isotopic signature for the San Diablo rocks is consistent with magma genesis in a moderately juvenile-like accretionary arc, where the calc-alkaline types show a subduction-related signature. In contrast, the country rocks in the adjoining Paraguá Domain show published Sm–Nd T DM model ages of ca. 1.55 to 2.48 Ga and ε NdT values of −4.9 to +5.2, pointing to distinct protoliths in the magma genesis. The Yarituses Suite includes the following granites: La Cruz (1673 ± 21 Ma), Refugio (1673 ± 25 Ma; 1641 ± 4 Ma), San Pablo (1609 ± 17 Ma), San Miguel (1681 ± 13 Ma), and Rosario (1678 ± 21 Ma). These granites yield variable Sm–Nd T DM model ages of ca. 1.67 to 2.48 Ga and ε NdT of +4.1 to −3. 8 (Ta ble 1), suggesti ng the derivation of distinct crustal components. The new and compiled data demonstrate first time that the Lomas Maneches and Yarituses suites, in conjunction with the Chiquitania complex and the newly dated Ambaybo rhyolite (1691 ± 8 Ma) of the San Ignacio Schist Group, belong to a distinct tectonic-magmatic episode akin to an active continental margin. The Pensamiento Granitoid Complex (1440-1270 Ma) shows documented Sm–Nd T DM model ages between ca. 1.55 and 2.42 Ga and predominantly crustal-like isotopic signatures as low as −4.6 typical of a continental arc setting. On a broader scale, the San Ignacio Granitoids are products of the Alto Guaporé orogeny, previously established in the Brazilian counterpart, characterized by an accretionary phase (ca. 1440 Ma) and a collisional one (ca. 1330 Ma) against the active margin of proto-Amazonia at the Ectasian. The regional structural framework of those plutons in the Bolivian counterpart suggests that the San Ramón and Coronación granodiorites (1429-1423 Ma) are pre-to syn-kinematic to the collisional phase. In contrast, the La Junta (1380 ± 17 Ma) and San Martin (1409 ± 17 Ma) granites are syn-to-late kinematic. The Diamantina granite (1357 ± 19 Ma) is coeval with the Alto Guaporé collisional phase, while the San Andrés granite (1289-1275 Ma) is a post-kinematic pluton. The ε NdT of the Pensamiento Granitoid Complex varies from +5.2 to −4.6. The onset of the Sunsás orogeny, characterized by an allochthonous collisional-type belt (1.2–1.0 Ga) ends the polycyclic evolution of the Bolivian Precambrian Shield, leading to tectonic stability of the Amazonian Craton. • The Precambrian Shield of Bolivia comprises two different domains: The San Diablo and Paraguá, each with different structural and tectonic settings. • The oldest rock in the San Diablo Domain has 1941 Ma and is metamorphosed into amphibolite metamorphic facies. The Paraguá Domain comprises the Lomas Maneches Granulite Complex of 1818 Ma and contains high-grade metamorphic rocks with granulite facies. A new unit called Yarituses Suite crops out in the Paraguá domain, comprising granites from 1683 to 1610 Ma. The San Ignacio granites from 1450 to 1275 Ma crop out in both domains, e.g., San Diablo and Paraguá. [ABSTRACT FROM AUTHOR]

LA-ICPMS U-Pb isotopic studies are conducted for key samples from the Itapecerica graphite-rich supracrustal succession and the crystalline basement in the southern São Francisco Craton (SFC). The detrital zircon analyses in paragneiss indicated a maximum deposition age of ∼2080 Ma. The age spectra in the relative probability diagrams suggested the precursor basin was essentially fed with detritus from the accretionary complexes of the Mineiro belt (2470–2000 Ma), which is the most preserved segment of the Minas Orogen. The basement rocks yielded zircon U-Pb crystallization ages between 2753 ± 81 and 2679 ± 61 Ma, whereas the metamorphic overprint gave 2069 ± 84 Ma. One nearby charnockitic gneiss yielded a Sm-Nd garnet + whole rock linear array with an age of 2086 ± 19 Ma. The youngest ages estimate the timing of the regional prograde granulite facies metamorphism that also overprinted the Itapecerica rocks, given our upper intercept zircon U-Pb ages of 1997 ± 20 Ma and 1971 ± 40 Ma in paragneiss and quartzite, respectively. These ages also constrained the timing of the conversion of carbonaceous material into graphite in the Itapecerica mine – the second largest graphite mine in Brazil. The high-grade metamorphism was associated with the final docking of the Mineiro belt against the Neoarchean foreland. The Minas Orogen has geologic matches with the Jiao-Liao-Ji Orogen located in the present eastern margin of the North China Craton, where khondalites, UHT granulites, anatectic charnockites, as well as large graphite deposits are documented such as in the 1.97–1.88 Ga Korean arc. The tectonic similarities between the two cratons support a relatively close position at the time frame. The dynamic scenario considers broadly coeval accretionary/collisional belts along the active margins of Archean blocks, the progressive closure of the Paleoproterozoic Ocean and final docking of the São Francisco/Congo paleocontinent against the active continental margin of the North China Craton. The work model allows new insights into the paleogeography of the core of supercontinent Columbia at ∼1.90 Ga and the subsequent (1.78–1.50 Ga) intraplate activity. [ABSTRACT FROM AUTHOR]

Abstract: The Figueira Branca Suite (FBS) comprises a layered mafic–ultramafic complex which together with mafic–felsic plugs makes up a string of NW-trending intrusive bodies that are emplaced into the Jauru domain (Rio Negro-Juruena province; 1.80–1.60Ga). This domain comprises Orosirian calc-alkaline rocks and coeval metamorphic volcanic–sedimentary associations, intruded by voluminous granitoid plutons resulted from outboard Cachoeirinha (1587–1522Ma) and Santa Helena (1485–1420Ma) accretionary orogens that eventually created the Rondonian-San Ignacio province along the SW margin of the proto-Amazonian Craton. SHRIMP U–Pb age in zircon for one cumulatic gabbro from the FBS yielded a concordia intercept age of 1425.5±8.0Ma (MSWD=1.11). Another gabbroic plug which crops out to the East gives a similar within error concordia intercept zircon age of 1415.9±6.9Ma (MSWD=0.25), whereas a nearby monzogranite yields a concordia intercept zircon age of 1428.9±2.8Ma (MSWD=1.30). All these results are crystallization ages and constrain an important intraplate magmatic event within the Orosirian continental crust at the time of outboard Santa Helena orogen. On the other hand, igneous titanite from another gabbro located to the West of the FBS yielded a weighted mean 207Pb/206Pb crystallization age of 1541±23Ma (MSWD=0.74). Therefore this rock is not genetically associated with the FBS, as previously suggested by the field information. Additional Nd–Sr isotopic analyses of the FBS mafic–ultramafic rocks and coeval gabbro showed comparable ɛ Nd(1.42Ga) values (+3.0 to +4.7) and variable ɛ Sr(1.42Ga) ones (−39.1 to −8.1). These data plot in the depleted field quadrant of the Nd–Sr diagram, indicating a significant influence of the MORB end-member reservoir in the magma genesis. This interpretation is similarly supported by comparison of the Nd evolutionary path of the FBS with those that characterize the isotopic evolution of the Jauru crust and the Cachoeirinha and Santa Helena intrusive plutons. The bulk isotopic signature allows the genetic relationship among the Santa Helena Suite and the FBS and coeval rocks. The anorogenic character of the FBS is supported by the geologic framework of the Jauru domain, given that the emplacement took place under an extensional regime, associated with the recognized regional NW-trending structures. 40Ar–39Ar analyses were carried out in mafic rocks that are assigned to the FBS. Biotite from a gabbronorite yielded an ideogram age of 1222±5Ma while a nearby troctolite yielded plateau biotite ages of 1275±4Ma and 1268±4Ma. These ages are minimum estimates of the regional cooling of the FBS. One gabbro of the Alto Jauru Group yields a 40Ar–39Ar plateau age of 1781±15Ma, interpreted as the time of regional cooling that succeeded continental accretion and metamorphism at Orosirian times. Later on heterogenous crustal thickening and uplift took place from West to East, as response from the Cachoeirinha and Santa Helena orogen dynamics, which is marked by the 1539–1510Ma and 1452–1322Ma 40Ar–39Ar age-patterns, respectively. The available apparent ages suggest that Cachoeirinha crust was subjected to a fast exhumation rate (ca. 50m.y.), as estimated by the zircon–titanite–hornblende–biotite time-path, while the Santa Helena crust seems to display a lower exhumation rate. Particularly, the youngest 40Ar–39Ar biotite age (1322Ma) available for the Santa Helena crust signals the post-tectonic phase of the Rondonian-San Ignacio province. [Copyright &y& Elsevier]

Abstract: The Serrinha magmatic suite (Mineiro belt) crops out in the southern edge of the São Francisco craton, comprising the Brito quartz-diorite, Brumado de Cima and Brumado de Baixo granodiorites, granophyres and felsic sub-volcanic and volcanic rocks, part of which intruded into the Nazareno greenstone belt. The suite rocks have petrographic features that are consistent with magma supercooling due to the low water content combined with volatile loss, leading to crystallization of quartz and alkaline feldspar at the rims of plagioclase phenocrysts (granophyric intergrowth). The investigated rocks are sub-alkaline, calc-alkaline and show low content in rare earth elements. The U–Pb zircon crystallization ages for the Brumado de Cima granodiorite [2227±22 (23) Ma] and a coeval granophyre [2211±22 (23) Ma], coupled with available single-zircon Pb evaporation ages for the Brito and Brumado de Baixo plutons, are significantly older than the “Minas orogeny” (ca. 2100–2050Ga) of Quadrilátero Ferrífero area, eastward from the Serrinha suite. Our data establish an early Rhyacian event tectonically linked with the evolution of the Mineiro belt. The bulk Nd isotopic signature [low negative to positive ε Nd( t ) values] of the Serrinha samples are consistent with the important role of Paleoproterozoic mantle components in the magma genesis. The integrated geologic, geochemical and isotopic information suggests that Paleoproterozoic evolution of the Mineiro belt initiated in a passive continental margin basin with deposition of the Minas Supergroup at ca. 2500Ma. This stage was succeeded by outboard rupture of the oceanic lithosphere with development and coalescence of progressively younger magmatic arcs during Rhyacian time. One of the earliest arcs formed the Serrinha suite. The tectonic collage of the Serrinha and Ritápolis (2190–2120Ma) arcs produced the NE–SW Lenheiro shear zone, resulting in mylonitization and recrystallization of both the granitoid intrusions and host rocks. As a matter of fact juxtaposition of distinct magmatic units in age and origin took place along the Lenheiros structure in this sector of the Mineiro belt. [Copyright &y& Elsevier]

• Siderian-Rhyacian orogeny formed the Juiz de Fora Complex. • Juvenile accretion at ca. 2.44 Ga marks a primitive intra-oceanic arc setting. • Coeval TTG-Sanukitoid suites at ca. 2.20 Ga marks the mature arc setting. • ca. 2.03 Ga metamorphic zircon records the collision with the Mantiqueira Complex. The Juiz de Fora Complex (JFC) is one of the basement units of the Occidental Terrane, Central Ribeira belt, in the Neoproterozoic framework of Western Gondwana, regarded as part of the reworked border of the São Francisco Paleocontinent. The JFC comprises Paleoproterozoic granitoid rocks with TTG, calc-alkaline, sanukitoid, and tholeiite-type geochemical compositions. They exhibit complex deformational fabrics associated with two episodes of granulite-facies metamorphism, occuring in the early Orosirian and the Ediacaran. The new U-Pb (SHRIMP) isotopic ages and Lu-Hf (LA-MC-ICPMS) data combined with available lithogeochemical, whole-rock Sm-Nd and Rb-Sr isotopic data constrain the tectonic evolution of the JFC to a Siderian-Rhyacian evolved arc system. Five samples were selected for U-Pb geochronology and Lu-Hf analysis on zircon grains: a low-K tholeiite, one TTG, two sanukitoids, and a mafic tholeiite. Combined whole-rock Sm-Nd, Rb-Sr isotopes, and zircon Lu-Hf isotopic data suggest the following evolution: an initial moderately juvenile (2445 Ma) low-K tholeiitic magmatism (εNd(t) of − 0.1; εHf(t) from − 8 to + 3), followed by a moderately juvenile to evolved (2200–2182 Ma) coeval TTG-sanukitoid pulse (εNd(t) from − 0.6 to − 4.8; εHf(t) from − 11.7 to + 2.5), and eventually by a moderately juvenile (2130 Ma) tholeiitic magmatism (εNd(t) = − 0.05). The integrated information provides preliminary petrogenetic insights for these magmatic episodes, such as interaction between mantle sources and supracrustal subducted material, melting of the oceanic slab, and crustal assimilation. A ca. 2035 Ma collisional granulite event recorded in metamorphic rims and neoformed zircon grains in leucosomes, possibly marks the amalgamation of the JFC onto the Mantiqueira Complex. Geochronological and isotopic correlations with coeval terranes of the Minas-Bahia Orogen in the Brazilian and African counterparts are addressed for tectonic implications at a broader scale. [ABSTRACT FROM AUTHOR]

In the Famatina range, Sierras Pampeanas of Argentina (SW Gondwana), subvertical calc-alkaline lamprophyric dike swarms crop out through >300 km. The dikes cut Ordovician units with a prominent NW-SE trending and are covered by continental sedimentary successions of Pennsylvanian to Permian age. The dikes show a strong structural control associated with Riedel fault systems. Detailed field analysis suggested a ∼N-S opening direction oblique to the attitude of dike walls and a left-lateral transtensional tectonics during the emplacement. 40 Ar/ 39 Ar geochronology of a lamprophyric sample defined a crystallization age (plateau; whole rock) of 357.1 ± 7.1 Ma (MSWD = 2.3). Coetaneous ductile zones with dominant strike-slip motion, documented along western Argentina for >600 km, suggest a regional event in SW Gondwana during the Mississippian. We propose that this deformation was the result of the counterclockwise fast rotation of Gondwana between 365 and 345 Ma, when the Famatina range and western Argentina occupied a sub-polar position. A transform margin along SW Gondwana better explains our (and others) data rather than a subduction margin. This scenario is also consistent with the occurrence of A-type granites and normal-fault basins within the foreland as well as bimodal volcanics. [ABSTRACT FROM AUTHOR]

Abstract: Paleomagnetic, magnetic anisotropy data and 40Ar/39Ar ages are presented for high-grade metamorphic rocks of the Jequié block, São Francisco Craton. Jequié charnockites and enderbites gneisses from the eastern border of the block present northern and steep-downward directions, carried by Ti-poor titanomagnetite with high unblocking temperatures (550–600°C). A mean direction for 12 sites of enderbites from the eastern sector yielded a magnetic component A (D m =47.0°, I m =75.7°, α 95 =6.3°, K =48.8) with a corresponding paleomagnetic pole at 339.6°E, 5.4°N (A 95 =11.2°). Sites sampled on other metamorphic rocks including granulite-facies, tonalites and dacites yield different magnetic components. Anisotropy of magnetic susceptibility measured for all sampling sites shows a high degree of anisotropy (P =1.121–1.881), with NE- or NW-trending magnetic lineations and vertical magnetic foliations. These data were used to correct the mean site directions for all components. While the other components presented larger scatter after anisotropy correction, the component A shows a slightly tighter clustering of magnetic directions (D m =61.2°, I m =76.5°, α 95 =5.4°, K =66.2) giving a new, anisotropy corrected paleomagnetic pole at 342.1°E, −0.5°N (A 95 =9.6°). 40Ar–39Ar plateau ages of 2035±4Ma (hornblende) and 1876±4Ma (biotite) obtained for one of the samples with component A imply a very low cooling-rate of 1.4°C/Ma for these rocks. Based on these ages and corrected unblocking temperatures of the magnetic component A, we argue that the characteristic magnetization of the Jequié metamorphic rocks was acquired by high temperature thermo-chemical processes during regional cooling of the adjacent Itabuna–Salvador–Curaçá belt between 2089 and 1985Ma (pole age likely at 1.99Ga). Comparison of this pole with available paleomagnetic poles from South America and Africa suggests that neither Atlantica nor Ur have ever existed, and dispersed continental fragments dominated the paleogeography at ca. 2.0Ga ago. [Copyright &y& Elsevier]