The A-type granitoids: A review of their occurrence and chemical characteristics and speculations on their petrogenesis

Eby, G. Nelson

doi:10.1016/0024-4937(90)90043-z

Cited by 1,399 publications

(707 citation statements)

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“…1); we present its geochernistry in Table 1. Major element geochemistry indicates that VEL-6017 is metaluminous (aluminurn saturation index < 1.0) and can be chemically defined as an A-type granitoid, in agreement with Whalen et al (1987), Eby (1990), and Scheepers (2000), displaying high total alkalis (8.56 % ), high F e2 o~otallMgO (45.75) ra tios, and low CaO, Sr, and P 2 0 5 contents. It is also silica rich.…”

Section: General Geochemistry Characteristicsmentioning

confidence: 88%

The San Blas Pluton: An example of Carboniferous plutonism in the Sierras Pampeanas, Argentina

Dahlquist

Pankhurst

Rapela

et al. 2006

Journal of South American Earth Sciences

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AbstraetNew geoehronologieal and geoehemieal data are reported for the San BIas Pluton (SBP), in the northwestern Sierra de Velaseo, Sierras Pampeanas, whieh intrudes Ordovieian granitoids developed during the Famatinian orogeny. A precise Carboniferous age of 340 ± 3 Ma is established by U-Pb dating of zireon using a sensitive high-resolution ion mieroprobe (SHRIMP). The SBP illustrates several petrologieal and geoehemieal eharaeteristies of previously reported Carboniferous granitoids in the Sierras Pampeanas. Their generation is eonsistent with a regional reheating of the erust at approximately 342 Ma, whieh resulted in the forn1ation of relatively large amounts of granitie melts that were emplaeed in higher erustallevels along master fractures (older master shear zones ofLower Paleozoie age). The SBP can be ehemieally defined as a typieal A-type granitoid related to posteollisonal or postorogenie magmatism. Its high REE eontent and extraordinarily high U and Th eoneentrations may have eeonomie signifieanee. Many previously published Devonian and Carboniferous K-Ar dates are reset Ordovieian ages, but the existenee of other Carboniferous bodies in the Sierra de Velaseo eannot be diseounted until detailed mapping of the whole Sierra is eompleted.

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Section: General Geochemistry Characteristicsmentioning

confidence: 88%

The San Blas Pluton: An example of Carboniferous plutonism in the Sierras Pampeanas, Argentina

Dahlquist

Pankhurst

Rapela

et al. 2006

Journal of South American Earth Sciences

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“…Three samples (09AL12-1, 09AL12-2, 09AL12-3) show negative anomalies in Ba, Nb, Ta, Sr, P, Eu and Ti (Fig. 4c), characteristics of A-type granites (e.g., Eby, 1990Eby, , 1992Yang et al, 2006). The HREE abundances of the granodiorites are lower than those of the monzogranites.…”

Section: The Granitoids From Bayannuoergong Batholithmentioning

confidence: 98%

An Early Permian (ca. 280Ma) silicic igneous province in the Alxa Block, NW China: A magmatic flare-up triggered by a mantle-plume?

Wei

Wang

et al. 2014

Lithos

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“…A-type granites are commonly found in within-plate anorogenic settings or in the final stages of an orogenic event (e.g. Collins et al 1982, Clemens et al 1986, Whalen et al 1987, Eby 1990, 1992, Dall'Agnol et al 1994. The melting of the lower crust associated to mantle plume action or extensional thinning of the lithosphere associated with stress release-stages and generation of faults or mega-fractures are some of the tectonic models for A-type granites production (e.g.…”

Section: Discussionmentioning

confidence: 99%

“…Collins et al 1982, Clemens et al 1986, Whalen et al 1987, Eby 1990, 1992. On the Zr+Nb+Ce+Y versus 10 4 Ga/Al diagram, the samples plot in the A-type granites field (Fig.…”

Section: Petrographymentioning

confidence: 96%

K'Mudku A-type magmatism in the southernmost Guyana Shield, central-north Amazon Craton (Brazil): the case of Pedra do Gavião syenogranite

Souza

Dantas

et al. 2015

Braz. J. Geol.

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<p>The Mesoproterozoic K'Mudku event (1490 - 1147 Ma) is represented by a britlle-ductile shear belt that cuts across the Paleoproterozoic units in the southernmost Guyana shield, central-north Amazon craton. This event produced mylonitization and cataclasites at low/medium- to high-grade metamorphic, and local within-plate magmatism. In the Amazonas State, Brazil, A-type magmatism chronologically associated to K'Mudku has been reported for the Pedra do Gavião and Samaúma syenogranites. However, the spatial relationship between K´Mudku event and A-type magma generation are not yet adequately clarified in the region. The Pedra do Gavião syenogranite is a high-K alkaline, metaluminous, reduced A-type granite with a post-collisional to within-plate geochemical signature. It has U-Pb zircons crystallization age of 1218 Ma and inherited zircons with ages between 1820 and 1720 Ma, which, together with the Sm-Nd data, suggest melting of Paleoproterozoic basement rocks of the Cauaburi Complex (1810 - 1780 Ma) regional unit. These data demonstrate that the effects of the A-type magmatism associated to the end of the Grenvillian-Sunsas orogeny, reported primarily in the southwestern margin of the Amazon craton, may also be extended for the central-northern part of the Amazon craton. Probably the generation or emplacement mechanisms of A-type magma occurred with some degree of involvement in the final stages of the K´Mudku event. However, this tectonic framework conception still needs more geological and geophysical investigations. Therefore, these news data should instigate to the return of geological research in the region, as well as to debate on the tectonic evolution and A-type granites production during the Ectasian-Stenian period in the central-north Amazon craton.</p>

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The A-type granitoids: A review of their occurrence and chemical characteristics and speculations on their petrogenesis

Cited by 1,399 publications

References 53 publications

The San Blas Pluton: An example of Carboniferous plutonism in the Sierras Pampeanas, Argentina

The San Blas Pluton: An example of Carboniferous plutonism in the Sierras Pampeanas, Argentina

An Early Permian (ca. 280Ma) silicic igneous province in the Alxa Block, NW China: A magmatic flare-up triggered by a mantle-plume?

K'Mudku A-type magmatism in the southernmost Guyana Shield, central-north Amazon Craton (Brazil): the case of Pedra do Gavião syenogranite

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