Two cryptic anatectic events within a syn-collisional granitoid from the Araçuaí orogen (southeastern Brazil): Evidence from the polymetamorphic Carlos Chagas batholith

Melo, Marilane Gonzaga de; Stevens, Gary; Lana, Cristiano; Pedrosa-Soares, Antônio Carlos; Frei, Dirk; Alkmim, Fernando Flecha de; Alkmin, Leonardo Azevedo Sá

doi:10.1016/j.lithos.2016.10.012

Cited by 47 publications

(58 citation statements)

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“…This is in contrast with the hot thermal regime registered from the neighbour Carlos Chagas Batholith, located 50 km to the east, within the eastern domain ( Fig. 1b; Melo et al, 2016). In fact, this batholith records granulite-facies metamorphism (0.9-1.0 GPa and 790-820°C) at 570 Ma, age at which: 1) the Galiléia granitoids were already crystallized (632-570 Ma; Tedeschi et al, 2016) and 2) the Araçuaí Orogen was experiencing syn-collisional tectonics (Pedrosa-Soaeres et al, 2011).…”

Section: Geotectonic Implications: a New Tectonic Model For The Araçacontrasting

confidence: 75%

“…Richter et al, 2015) and into the Carlos Chagas batholith characterized by peraluminous S-type granitoids (e.g. Melo et al, 2016). These rocks, according mainly to their location, ages and geochemistry (Pedrosa-Soares et al, 2001), are subdivided in syn-collisional (G2, 585-560 Ma), late collisional (G3; 560-530 Ma) and post-collisional (G4-G5, 530-480 Ma) supersuites.…”

Section: General Background Of the Araçuaí Orogenic Beltmentioning

confidence: 99%

“…Stype granites). In these rocks, garnet has been shown to be commonly peritectic, produced by biotite incongruent melting of the metapelitic source of the S-type magma, or due to partial melting of metasedimentary country rock which the magma intruded (Erdmann et al, 2009;Lackey et al, 2012;Melo et al, 2016). Furthermore, garnet has also been proposed to represent entrained crystals from the source, that were not involved in the anatectic process (i.e.…”

Section: Introductionmentioning

confidence: 99%

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Magmatic garnet in the Cordilleran-type Galiléia granitoids of the Araçuaí belt (Brazil): Evidence for crystallization in the lower crust

Narduzzi

Farina

Stevens

et al. 2017

Lithos

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Magmatic garnet, together with epidote, is a rare mineral association in cordilleran-I-type granitoids and of special petrogenetic significance. The metaluminous to slightly peraluminous (ASI = 0.97-1.07) Galiléia batholith (Brazil) is a large (ca. 30,000 km 2 ), Neoproterozoic (ca. 632-570 Ma) weakly foliated calc-alkaline granitoid body, characterized by the widespread occurrence of garnet (grossular 25-43 mol%) and epidote (pistacite 9.3-22.7 mol%). Field, petrographic and mineral chemical evidence indicates that garnet, epidote, biotite as well as white mica crystals (low-Si phengite), are magmatic. There is no difference in bulk rock major and trace element composition between the Galiléia granitoids and other garnet-free cordilleran-type granitoids worldwide. This evidence strongly suggests that the origin of the uncommon garnet + epidote parageneses is related to the conditions of magma crystallization, such as pressure, temperature and water content. Comparison between the mineral assemblages and mineral compositions from this study and those recorded in crystallization experiments on metaluminous calc-alkaline magmas, as well as within garnet-bearing metaluminous volcanic rocks and granitoids, indicates that the supersolidus coexistence of grossular-rich garnet, epidote and white mica is consistent with magma crystallization at pressures greater than 0.8 GPa (above 25 km depth) and at temperatures below 700°C, i.e. near the water saturated solidus. Furthermore, resorption textures around garnet (plagioclase ± quartz coronas) and epidote suggest that these minerals have been partially consumed prior to complete crystallization. These findings demonstrate that at 630 Ma the crust underneath the Araçuaí Orogen was already at least 25-30 km thick and relatively cool. However, this contrasts with the marked high heat flow registered from the neighbour Carlos Chagas Batholith located 50 km to the east. In fact such granitoids record granulite-facies metamorphism at the same pressure and time (ca. 570 Ma) of Galiléia granitoids crystallization. Thus, a more suitable geodynamic scenario is required in order to explain these two contrasting thermal regimes within the same orogen. Eventually, field, petrographic and mineral chemical analogies with similar garnet-bearing granitoids located in the fore-arc settings of the British Columbia subduction zone, possibly imply that the Galiléia granitoids represent "rare" garnet-and epidote-bearing metaluminous Cordilleran-Itype granites which can only form in a fore-arc setting.

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Section: Geotectonic Implications: a New Tectonic Model For The Araçacontrasting

confidence: 75%

Section: General Background Of the Araçuaí Orogenic Beltmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Magmatic garnet in the Cordilleran-type Galiléia granitoids of the Araçuaí belt (Brazil): Evidence for crystallization in the lower crust

Narduzzi

Farina

Stevens

et al. 2017

Lithos

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“…The precise 569 ± 6 Ma LA‐ICP‐MS concordant age obtained on sample 146 (M‐Domain II) restricts this group to the 565–575 Ma interval. This interval, as documented by various authors, represents the time of the largest production of syn‐collisional crustal melts in the Araçuaí orogen, represented by the leucogranites of the G2 Granite Supersuite (Gradim et al., ; Melo et al., ; Pedrosa‐Soares, De Campo et al., ; Peixoto et al., ; Richter et al., ; Silva, Pedrosa‐Soares, Armstrong, & Noce, ). Thus, ages of this group record the syn‐collisonal Barrovian metamorphic event in both domains.…”

Section: Discussion and Synthesismentioning

confidence: 82%

“…The following lithostratigraphic units are involved in this portion of the orogen (Figures 1–3): (1) a basement assemblage containing rocks older than 1.8 Ga, locally represented by gneisses and granitoids of the Porteirinha Complex (Noce, Pedrosa‐Soares, Silva, Armstrong, & Piuzana, ; Silva et al., ); (2) the rift‐sag sequences of the Espinhaço Supergroup deposited between 1.78 and 1.00 Ga (Chemale et al., ; Dussin & Dussin, ; Martins‐Neto, ); (3) the Macaúbas Group, a glacially influenced rift to passive margin succession accumulated between c . 850 and 600 Ma, and made up of metasandstones, metapelites and metadiamictites containing lenses and layers of banded iron formation, metacarbonates and metavolcanic rocks (Kuchenbecker, Pedrosa‐Soares, Babinski, & Fanning, ; Noce et al., ; Pedrosa‐Soares & Alkmim, ; Pedrosa‐Soares, Babinski et al., ); (4) syn‐collisonal granites emplaced between 630 and 580 Ma and grouped into the G2 and G3 supersuites (Gradim et al., ; Melo et al., ; Pedrosa‐Soares, De Campo et al., ); (5) the syn‐orogenic Salinas Formation, composed of turbiditic metasandstones, schists and metaconglomerates accumulated between 580 and 544 Ma (Lima, Martins‐Neto, Pedrosa‐Soares, Cordani, & Nutman, ; Peixoto, Pedrosa‐Soares, Alkmim, & Dussin, ; Santos, Alkmim, & Pedrosa‐Soares, ); and (6) late‐ to post‐collisional granites of the G4 and G5 supersuites, emplaced from 530 to 490 Ma (De Campos et al., , ; Pedrosa‐Soares & Wiedemann‐Leonardos, ; Pedrosa‐Soares, De Campo et al., ).…”

Section: Geological Settingmentioning

confidence: 99%

Metamorphic record of collision and collapse in the Ediacaran‐Cambrian Araçuaí orogen, SE‐Brazil: Insights from P–T pseudosections and monazite dating

Peixoto

Alkmim

Pedrosa-Soares

et al. 2017

Journal Metamorphic Geology

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The Araçuaí orogen is the Brazilian counterpart of the Araçuaí‐West Congo orogenic system (AWCO), a component of the Ediacaran‐Cambrian orogenic network formed during the amalgamation of West Gondwana. The northwestern portion of the Araçuaí orogen is dominated by a succession of metasedimentary rocks made up of Meso‐ to Neoproterozoic rift, passive margin and syn‐orogenic sequences, locally intruded by post‐collisional granites. These sequences are involved in three distinct tectonic units, which from west to east are: the southern Espinhaço fold‐thrust system (SE‐thrust system), the normal‐sense Chapada Acauã shear zone (CASZ) and the Salinas synclinorium. Three deformation phases were documented in the region. The first two phases (D1 and D2) are characterized by contractional structures and represent the collisional development stage of the orogen. The third phase (D3) is extensional and currently viewed as a manifestation of orogenic collapse of the system. The distribution of the metamorphic mineral assemblages in the region characterizes two metamorphic domains. The M‐Domain I on the west, encompassing the SE‐thrust system and the CASZ, is marked by a syn‐collisional (syn‐D1) Barrovian‐type metamorphism with P–T conditions increasing eastwards and reaching ~8.5 kbar at ~650°C between 575 and 565 Ma. The M‐Domain II comprises the Salinas synclinorium in the hangingwall of the CASZ, and besides the greenschist facies syn‐collisional metamorphism, records mainly a Buchan‐type metamorphic event, which took place under 3–5.5 kbar and up to 640°C at c. 530 Ma. The northwestern Araçuaí orogen exhibits, thus, a paired metamorphic pattern, in which the Barrovian and Buchan‐type metamorphic domains are juxtaposed by a normal‐sense shear zone. Lithospheric thinning during the extensional collapse of the orogen promoted ascent of the geotherms and melt generation. A large volume of granites was emplaced in the high grade and anatectic core of the orogen during this stage, and heat advected from these intrusions caused the development of Buchan facies series over a relatively large area. Renewed granite plutonism, hydrothermal activities followed by progressive cooling affected the system between 530 and 490 Ma.

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Fluid-induced alteration of monazite, magnetite, and sulphides during the albitization of a Palaeoproterozoic granite from the Jiao-Liao-Ji orogenic belt, North China Craton

Lei

Liu

Harlov

et al. 2021

Contrib Mineral Petrol

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Two cryptic anatectic events within a syn-collisional granitoid from the Araçuaí orogen (southeastern Brazil): Evidence from the polymetamorphic Carlos Chagas batholith

Cited by 47 publications

References 54 publications

Magmatic garnet in the Cordilleran-type Galiléia granitoids of the Araçuaí belt (Brazil): Evidence for crystallization in the lower crust

Magmatic garnet in the Cordilleran-type Galiléia granitoids of the Araçuaí belt (Brazil): Evidence for crystallization in the lower crust

Metamorphic record of collision and collapse in the Ediacaran‐Cambrian Araçuaí orogen, SE‐Brazil: Insights from P–T pseudosections and monazite dating

Fluid-induced alteration of monazite, magnetite, and sulphides during the albitization of a Palaeoproterozoic granite from the Jiao-Liao-Ji orogenic belt, North China Craton

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