Pluton emplacement in a releasing bend in a transpressive regime: the arrozal granite in the Paraíba do Sul shear belt, Rio de Janeiro

Nummer, Alexis Rosa; Machado, Rômulo; Dehler, Nolan Maia

doi:10.1590/s0001-37652007000200011

Cited by 10 publications

(9 citation statements)

References 16 publications

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“…The length of Phulad granite is more than 200 km long and~6 km wide (maximum width 9 km) suggesting strong tabular body with long axis parallel to the shear zone (Figure 1b). This remarkable narrowness of Phulad granite may be because of transpression shear zone extending along the orogen length (Crawford et al, 1987;Hutton, 1997;Ingram & Hutton, 1994;Klepeis & Crawford, 1999;McCaffrey, 1989McCaffrey, , 1992Nummer et al, 2007;Saint Blanquat et al, 1998). The magmatic foliation and the solid-state foliation in the Phulad granite are parallel ( Figures 6 and 7).…”

Section: Evidence Of Syntectonic Emplacement Of Phulad Granitementioning

confidence: 99%

“…Important studies of granitic rocks in transpressional orogens indicate that tectonics may act as fundamental controls on the ascent and emplacement of the granitic rocks (de Saint Blanquat et al, ; Hutton, , ; Hutton & Reavy, ; McCaffrey, ; Saint Blanquat et al, ). Syntectonic granite emplacements in broadly transpressive shear zones or along terrane boundaries have been reported from different parts of world and of diverse age (Crawford et al, ; D'Lemos et al, ; Guineberteau et al, ; Hutton, , , , , ; Hutton et al, ; Hutton & Reavy, ; Ingram & Hutton, ; Karlstrom, ; Klepeis & Crawford, ; McCaffrey, , ; Nummer et al, ; Reavy, ; Tikoff & Blanquat, ; Zibra et al, ). The mechanism of granite emplacement in these shear zones or terrane boundaries largely depends on the interaction between the ambient tectonic forces and the natural magma buoyancy (Hutton, ).…”

Section: Introductionmentioning

confidence: 99%

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Mid‐Neoproterozoic Tectonics of Northwestern India: Evidence of Stitching Pluton along 810 Ma Phulad Shear Zone

et al. 2020

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In northwestern India, Phulad Shear Zone (PSZ,~810 Ma) demarcates the boundary between South Delhi Fold Belt to the east and Marwar craton to the west. This shear zone has regional NE-SW trend with small bends of N-S orientations. PSZ is characterized by steep southeasterly dipping mylonitic foliation with steep oblique stretching lineation. The PSZ has developed in a ductile transpression with top-to-the-NNW reverse sense of movement associated with a component of sinistral-slip movement on horizontal section. The 200 by 6 km porphyritic Phulad granite occurs along and across the PSZ, and it is variably deformed. Phulad granite shows evidence of magmatic foliation with preservation of parallel alignment of euhedral feldspars phenocrysts and microgranitoid enclaves. The feldspar phenocrysts show simple twin interfaces parallel to the direction of elongation. This granite also shows development of solid-state foliation parallel to this magmatic foliation. Detailed study of structural elements suggests that Phulad granite has formed during the regional deformation in the country rock shear zone prior to its complete crystallization. Our data indicate that the releasing bends of N-S orientation within the PSZ have provided the space required for emplacement of Phulad granite in a transpressional regime. EPMA U-Pb-Th monazite and U-Pb LA-ICP-MS zircon ages in Phulad granite indicate a magmatic age of 819.1 ± 4 and 818 ± 18 Ma, respectively. PSZ represents the suture along which Marwar craton accreted with remaining India to form the Greater India landmass. The present study suggests that Phulad granite acted as a stitching pluton during this suturing along PSZ at 810-820 Ma.

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Section: Evidence Of Syntectonic Emplacement Of Phulad Granitementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mid‐Neoproterozoic Tectonics of Northwestern India: Evidence of Stitching Pluton along 810 Ma Phulad Shear Zone

et al. 2020

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“…The second group of granitoids in the Ribeira belt is composed of smaller massifs, such as stocks or small tabular or elongated batholith associated with regional, high-angle ductile shear zones (Nummer, 2001;Nummer et al, 2007). The plutons are foliated, with solid-state deformation especially at the borders and igneous flow structures in the nuclei.…”

Section: The Rio De Janeiro Neoproterozoic/cambrian Granitoidsmentioning

confidence: 99%

Geochemical and isotopic evidence for the petrogenesis and emplacement tectonics of the Serra dos Órgãos batholith in the Ribeira belt, Rio de Janeiro, Brazil

Machado

Philipp

McReath

et al. 2016

Journal of South American Earth Sciences

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The Serra dos Órgãos batholith in the State of Rio de Janeiro (Brazil) is a NE-SW-trending elongated body that occupies ca. 5,000 km 2 in plan view. It is a foliated intrusion, especially at its borders and is crosscut by syn-magmatic shear zones, with foliations that are moderately-to steeply-dipping to the northwest and moderately-to shallow-dipping in the center and to the southeast, in a configuration of a large laccolith. It was emplaced between 560 to 570 Ma, during an extensional episode that was part of a series of events that comprise the Brasiliano Orogeny in SE Brazil, and which includes deformation, metamorphism and granite intrusion during the interval between 630 and 480 Ma. The two main rock types in the batholith are biotite-hornblende monzogranite, and biotite leucogranite, with subordinate tonalite, granodiorite, diorite, quartz diorite (enclaves), aplite and pegmatite. Harker-type diagrams help show two rock groups with similar trends of evolution: a dioritic and a granitic. The first one is tholeiitic, whereas the second is calc-alkaline, with medium-to high-K calc-alkaline affinity and metaluminous to slightly peraluminous character. In both groups strong decrease in Al 2 O 3 , MgO, FeOT and CaO relative to silica contents are observed, which is compatible with trends of fractional crystallization involving clinopyroxene and/or hornblende, plagioclase, opaque minerals, apatite, microcline and biotite. The Sr and Nd isotopic data suggest recycling of a Paleoproterozoic crust as an important petrological process to generate the batholith rocks. Geothermometry (amphibole composition) and geobarometry (saturation in zircon and apatite) indicate that most of the batholith solidified at mid to lower crustal levels at about 750°C and between 5 and 5.5 kbar. We consider that Serra dos Órgãos crustal protoliths underwent melting caused by the interaction with hotter mafic magma at the base of the crust. These two magmas, with distinct initial compositions and rheology, probably underwent mixing and mingling. This process continued during the rise of the magma through the crust, which was accompanied by magmatic diffentiation. The main feature that characterizes the post-collisional Serra dos Órgãos granite magmatism is the connection with high angle ductile shear zones of continental scale and presence to a greater or lesser extent of mafic magmas.

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“…The structure of the Province is attributed to collision event(s) during western Gondwanaland agglutination (Heilbron Correspondence to: Rômulo Machado E-mail: rmachado@usp.br et al 2004). In the Province, mylonitic rocks developed under low to high-grade metamorphic conditions, and magmatic bodies of different compositions were intruded during shear zone activity (Nummer et al 2007). Because of their high silica or phyllosilicate contents, these shear zones form positive or negative features signatures in the relief that are recognizable in satellite or aero-geophysical images.…”

Section: Introductionmentioning

confidence: 99%

Transpressive dextral shear in the Italva-Itaperuna section, Northern State of Rio de Janeiro, Brazil

Karniol

Machado

Dehler

2008

An. Acad. Bras. Ciênc.

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Structural analysis carried out on a segment of the Neoproterozoic Ribeira Belt, southeastern Brazil, show that it represents part of the transpressive dextral orogen related to the Central Mantiqueira Province. NNE-trending and steeply dipping regional mylonitic belts form anastomosed geometry, and describe a map-scale, S-C-like structure that is characterized by their deflection towards NE near the Além Paraíba Lineament. Lithological and structural control related to deformation partition were responsible for the formation of felsic mylonitic granulites with S-type granites lenses developed in ductile shear zones, alternated with less deformed intermediate to basic granulites associated with charnockites. The dextral shear sense indicators are consistent with transpressive deformation in the region and are common especially at the border of the main shear zones. The presence of S-type leucogranite may lead to variations of linear and planar relationships, which result in local extension zones. These elements are consistent with oblique continental collision considering the São Francisco Craton as a stable block.

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Pluton emplacement in a releasing bend in a transpressive regime: the arrozal granite in the Paraíba do Sul shear belt, Rio de Janeiro

Cited by 10 publications

References 16 publications

Mid‐Neoproterozoic Tectonics of Northwestern India: Evidence of Stitching Pluton along 810 Ma Phulad Shear Zone

Mid‐Neoproterozoic Tectonics of Northwestern India: Evidence of Stitching Pluton along 810 Ma Phulad Shear Zone

Geochemical and isotopic evidence for the petrogenesis and emplacement tectonics of the Serra dos Órgãos batholith in the Ribeira belt, Rio de Janeiro, Brazil

Transpressive dextral shear in the Italva-Itaperuna section, Northern State of Rio de Janeiro, Brazil

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