Structural and metamorphic control on the exhumation of high-P granulites: The Carvalhos Klippe example, from the oriental Andrelândia Nappe System, southern portion of the Brasília Orogen, Brazil

Neto, Mário da Costa Campos; Cioffi, Cauê Rodrigues; Moraes, Renato; Motta, Rafael Gonçalves da; Siga, Oswaldo; Basei, Miguel Ângelo Stipp

doi:10.1016/j.precamres.2010.05.010

Cited by 68 publications

(32 citation statements)

References 68 publications

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“…Two monazite grains in sample 05b‐10‐102 yielded core and rim ages. The core ages of c. 619 and 614 Ma are statistically identical and identical to the age of 617.7 ± 1.3 Ma determined by ID‐TIMS analysis of monazite from this klippe (Campos Neto et al. , 2010).…”

Section: Discussionsupporting

confidence: 70%

“…, 2010). It is interpreted to have experienced similar peak metamorphic conditions as the Três Pontas–Varginha Nappe with high‐temperature growth of monazite close to the solidus at c. 618 Ma (Campos Neto et al. , 2010).…”

Section: Discussionmentioning

confidence: 98%

“…The Carvalhos Klippe is inferred to be part of the Três Pontas–Varginha Nappe now isolated in the southernmost portion of the Southern Brasília Belt (Campos Neto et al. , 2010).…”

Section: Discussionmentioning

confidence: 99%

“…, 2009). Klippen of high‐pressure granulite facies rocks in the southernmost portion of the Brasília Belt (Figs 2 & 3) are correlated with the Três Pontas–Varginha Nappe (Campos Neto et al. , 2010).…”

Section: Regional Geologymentioning

confidence: 98%

“…The Carvalhos Klippe is interpreted to be part of the Três Pontas–Varginha Nappe now isolated in the southernmost portion of the Southern Brasília Belt. Based on the mineral assemblages and thermobarometry, the granulites in the Klippe are inferred to have experienced peak metamorphic conditions similar to the Três Pontas–Varginha Nappe (825 °C & 1.2 GPa; Campos Neto et al. , 2010).…”

Section: Metamorphic Historymentioning

confidence: 99%

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In situ monazite (U–Th)–Pb ages from the Southern Brasília Belt, Brazil: constraints on the high‐temperature retrograde evolution of HP granulites

Reno

Piccoli

Brown

et al. 2011

Journal Metamorphic Geology

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In the southern sector of the Southern Brası´lia Belt, late Neoproterozoic arc-passive margin collision resulted in juxtaposition of an arc-derived nappe (the Socorro-Guaxupe´Nappe) over a stack of passive margin-derived nappes (the Andrelaˆndia Nappe Complex) that lies on top of autochthonous basement of the Sa˜o Francisco Craton. (U-Th)-Pb monazite ages are reported from the high-grade nappes of the Andrelaˆndia Nappe Complex to better constrain the high-temperature retrograde evolution. For residual HP granulites from the uppermost Treˆs Pontas-Varginha Nappe, (U-Th)-Pb ages of c. 662 and 655 Ma from low yttrium monazite inclusions in the rims of, or associated with garnet are interpreted to date the late-stage close-to-peak prograde evolution, whereas an age of c. 648 Ma from a similar low yttrium monazite inclusion is interpreted to record post-peak recrystallization with melt via factures in garnet. For the same nappe, ages of 640-631 Ma retrieved from higher yttrium areas or cores in monazite grains that occur both as inclusions in garnet and in the matrix are interpreted to record growth of monazite either by local breakdown of garnet (±older monazite) and mass exchange with a matrix melt reservoir along cracks or growth from residual melt in the matrix as it crystallized during high-pressure, closeto-isobaric cooling close to the solidus, the temperature of which, at a given pressure, varies with bulk composition of the residual granulites. (U-Th)-Pb ages in the range 620-588 Ma from lower yttrium areas in these monazite grains and from matrix-hosted patchy monazite are interpreted to date exhumation, as recorded by close-to-isothermal decompression and subsequent close-to-isobaric cooling. Older monazite ages in this group are interpreted to record late-stage interaction with melt close to the solidus whereas younger monazite ages are interpreted to record recrystallization of monazite by dissolution-reprecipitation owing to ingress of alkali fluid from the Carmo da Cachoeira Nappe beneath as fluid was released by crystallization of in-source melt at the solidus. In the underlying Carmo da Cachoeira Nappe, higher yttrium areas in monazite and one single domain monazite yield chemical ages of 619-616 Ma, which are interpreted to date growth as in-source melt crystallized close to the solidus along the high-pressure, close-to-isobaric segment of the retrograde P-T evolution. Younger (U-Th)-Pb ages of 600-595 Ma retrieved from lower yttrium areas and one single domain monazite are interpreted to record recrystallization of monazite by dissolution-reprecipitation owing to release of fluid at the solidus during exhumation of this nappe. Monazite from the Carvalhos Klippe, interpreted to be correlative with the uppermost nappe, yields a wide range of (U-Th)-Pb ages: for two zoned grains, c. 619 and c. 614 Ma from higher yttrium cores, and c. 583 and c. 595 Ma from lower yttrium rims; and, 592-580 Ma from single domain grains in one sample, and ages of c. 593 and c. 563 Ma from monazite in a second sa...

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Section: Discussionsupporting

confidence: 70%

Section: Discussionmentioning

confidence: 98%

“…The Carvalhos Klippe is inferred to be part of the Três Pontas–Varginha Nappe now isolated in the southernmost portion of the Southern Brasília Belt (Campos Neto et al. , 2010).…”

Section: Discussionmentioning

confidence: 99%

Section: Regional Geologymentioning

confidence: 98%

Section: Metamorphic Historymentioning

confidence: 99%

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