Shear Zones in Brasiliano-Pan-African Belts and Their Role in the Amalgamation and Break-Up of Southwest Gondwana

Oriolo, Sebastián; Hueck, Mathias; Oyhantçabal, Pedro; Goscombe, Ben; Wemmer, Klaus; Siegesmund, Siegfried

doi:10.1007/978-3-319-68920-3_22

Cited by 16 publications

(4 citation statements)

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“…The measured (U‐Th)/He data set is best explained by a shared geological history, as evidenced by the uniform coherent trends observed in the eU content versus ZHe/AHe age diagrams. Consequently, despite evidences of episodic Phanerozoic reactivation of shear zones in the Dom Feliciano Belt (Hueck et al, ; Oriolo et al, ), the MGSZ has not caused enough differential exhumation in order to leave a regional impact in the low‐T thermochronometers.…”

Section: Discussionmentioning

confidence: 99%

“…Separating the southeast and central domain, the Major Gercino Shear Zone (MGSZ) is the main structural feature of the Catarinense Shield (Figure ). It is characterized by kilometer‐wide mylonite belts enveloping sin‐transcurrent granitic intrusions (Bitencourt & Kruhl, ; Oriolo et al, ; Passarelli et al, ). Together with its extension in southernmost Brazil and Uruguay, the Dorsal do Canguçu, and Sierra Ballena Shear Zones, respectively, it forms a lineament over 1,000 km‐long that has been interpreted as a former suture zone (Basei et al, ; Passarelli et al, ).…”

Section: Geological Settingmentioning

confidence: 99%

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(U‐Th)/He Thermochronology and Zircon Radiation Damage in the South American Passive Margin: Thermal Overprint of the Paraná LIP?

et al. 2018

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New zircon and apatite (U-Th)/He data (AHe and ZHe) from the crystalline basement of the South American passive margin in southern Brazil present a wide distribution of Phanerozoic apparent ages, recording its prerift evolution. Its geological significance can be investigated by modeling the influence of the accumulated radiation damages on the measured crystals in its He ages during a long upper crust residence. Despite the presence of a significant fault in the studied area, the samples essentially constrain a uniform thermal history for the entire study area. Zircon helium ages spread from 472 to 26 Ma and correlate strongly with the radioactive element content of the crystals. Although the region was probably covered by Paleozoic sediments of the Paraná Basin, the ZHe system experienced a more intense thermal overprint, most likely the onset of the Paraná Large Igneous Province (LIP), causing its dispersion. The nearby intrusion of a feeding system of the LIP, the Florianópolis Dyke Swarm, may have contributed for keeping geothermal gradients elevated for a period long enough to promote the observed reset. After the extrusion of the volcanism, the study area was probably covered by up to 2 km of basalt floods, imprinting temperatures above the AHe partial retention zone on the crystalline basement. These were eroded during rapid cooling between 75 and 55 Ma, as indicated by thermal modeling. Additional analyses with Raman spectroscopy were used for calculating radiation damage ages in the zircon crystals measured for (U-Th)/He, resulting in a comparable set of ages.

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Section: Discussionmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

(U‐Th)/He Thermochronology and Zircon Radiation Damage in the South American Passive Margin: Thermal Overprint of the Paraná LIP?

et al. 2018

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“…They include a long-lived and huge calc-alkaline continental magmatic arc, a wide back-arc basin and the inverted sequences of the passive margins developed on the fringes of the Congo, Kalahari and Rio de la Plata cratons (Fig. 3a; Gray et al, 2008;Frimmel et al, 2013;Heilbron et al, 2008Heilbron et al, , 2017Oriolo et al, 2018;Basei et al, 2018). The widespread post-collisional magmatism and the presence of some metamorphic core complexes testify of a possible NS extensional collapse of the belt between the Cambrian and the Ordovocian (Heilbron et al, 2008;Goscombe et al, 2018;Hueck et al, 2018;Lehmann et al, 2016).…”

Section: Proterozoic Orogenymentioning

confidence: 98%

Conjugate volcanic passive margins in the austral segment of the South Atlantic – Architecture and development

Chauvet

Sapin

Geoffroy

et al. 2021

Earth-Science Reviews

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“…Even though the CLG is not a syn‐kinematic granite, the assemblage of microstructures recorded mainly in quartz, but also feldspars and micas, is the result of deformation and recovery processes (Passchier & Trouw, 2005) under the cooling trajectory of these rocks (~700–250°C). This is caused probably by reactivations and late movements of the Ayrosa Galvão Shear Zone (Figure 1b), since these processes are common in the shear zones of the southern Mantiqueira Province, as highlighted by Philipp (1998), Passarelli (2011), and Oriolo et al (2018).…”

Section: Discussionmentioning

confidence: 93%

Capão do Leão Granite: Highly differentiated garnet‐bearing magmatism in the southeastern Dom Feliciano Belt, Brazil

et al. 2020

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The Capão do Leão Granite (CLG; 583 ± 3 Ma) occurs as two NE‐oriented bodies, near the namesake city and Pedro Osório, Rio Grande do Sul, Brazil. The CLG is linked to the voluminous Ediacaran magmatism in the SE Dom Feliciano Belt (Pelotas Batholith), intruded in post‐collisional settings in the set of the non‐deformed younger plutons in the area. This work presents field characterization, petrography, mineral chemistry and whole‐rock geochemical affinities for the CLG. This granite exhibits miarolitic cavities, suggesting an epizonal emplacement, as well as mafic enclaves, which may represent source material, while mylonitic and S–C foliations are localized and post‐magmatic. The analysed samples are massive, leucocratic, coarse‐ to medium‐grained hypidiomorphic alkali‐feldspar granites composed of quartz, orthoclase (Or89–98), albite (An1–10), oligoclase (An11–16), garnet (Sps31–64 and Alm24–56), siderophyllite/annite, muscovite and Fe‐chlorite (secondary), apatite, epidote/zoisite, zircon, and opaques. The dispersion in mineral compositions in each occurrence and between them suggest different magmatic evolutionary trends. The diverse textures, zoning patterns and chemistry in garnet indicate both equilibrium with highly evolved Al2O3‐rich liquids, as well as a xenocrystic/restitic origin. The geochemistry shows subalkaline, high‐K, and metaluminous to weakly peraluminous fingerprints. Samples are commonly enriched in Rb, Th, U, Pb, Nd, and Sm, and depleted in Ba, Sr, Eu, Nb, P, Zr and Ti, due to advanced fractional crystallization. The classification of the CLG into some traditional chemical patterns is difficult, due to the high differentiation and the overlap of petrologic processes, although its derivation from I‐type liquids is proposed. The dispersion both in mineral and whole‐rock chemistry indicates different evolutionary trends for the CLG, where fractionation coupled with crustal recycling by assimilation/contamination processes were responsible for the granite differentiation.

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Shear Zones in Brasiliano-Pan-African Belts and Their Role in the Amalgamation and Break-Up of Southwest Gondwana

Cited by 16 publications

References 144 publications

(U‐Th)/He Thermochronology and Zircon Radiation Damage in the South American Passive Margin: Thermal Overprint of the Paraná LIP?

(U‐Th)/He Thermochronology and Zircon Radiation Damage in the South American Passive Margin: Thermal Overprint of the Paraná LIP?

Conjugate volcanic passive margins in the austral segment of the South Atlantic – Architecture and development

Capão do Leão Granite: Highly differentiated garnet‐bearing magmatism in the southeastern Dom Feliciano Belt, Brazil

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