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Tres Pontas-Varginha Nappe

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CL images of examples of zircons. (a) Zircon from the Socorro–Guaxupé Nappe (sample 04-7-1). (b) Zircon from leucosome close to the bottom of the Três Pontas–Varginha Nappe (sample 04-6-21). (c) Zircon associated with ilmenite in the middle of the Três Pontas–Varginha Nappe (sample 04-6-11). (d) Zircon from close to the top of the Três Pontas–Varginha Nappe (sample 05b-6-31b).

CL images of examples of zircons. ( a ) Zircon from the Socorro–Guaxupé Nap... Available to Purchase

Published: 01 December 2009
Fig. 3. CL images of examples of zircons. ( a ) Zircon from the Socorro–Guaxupé Nappe (sample 04-7-1). ( b ) Zircon from leucosome close to the bottom of the Três Pontas–Varginha Nappe (sample 04-6-21). ( c ) Zircon associated with ilmenite in the middle of the Três Pontas–Varginha Nappe (sample
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BSE images to show zircon microstructural settings. (a) Sample 04-7-1 is from the Socorro–Guaxupé Nappe; in this sample zircon occurs in leucosome. (b) Sample 05b-13-13 is a retrograded eclogite in which zircon occurs as inclusions in garnet or in the symplectic aggregates of plagioclase and clinopyroxene. (c) Sample 05b-6-31b is from the top of the Três Pontas–Varginha Nappe; in this sample zircon is associated with ilmenite both in the matrix and as inclusions in the mantles of garnet. (d–g) Sample 04-6-11 is from the top of the Três Pontas–Varginha Nappe; in this sample zircon is associated with ilmenite in leucosome.

BSE images to show zircon microstructural settings. ( a ) Sample 04-7-1 is ... Available to Purchase

Published: 01 December 2009
of plagioclase and clinopyroxene. ( c ) Sample 05b-6-31b is from the top of the Três Pontas–Varginha Nappe; in this sample zircon is associated with ilmenite both in the matrix and as inclusions in the mantles of garnet. ( d – g ) Sample 04-6-11 is from the top of the Três Pontas–Varginha Nappe; in this sample
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Isochemical phase diagrams for (a) sample 04-6-21 from close to the bottom of the Três Pontas–Varginha Nappe, and (b) sample 05b-6-31b from close to the top of the Três Pontas–Varginha Nappe. All assemblages also include quartz. Postulated schematic P–T path (0.15 GPa wide white arrow, which corresponds to an estimated nappe thickness of 5 km (Campos Neto & Caby 2000)) composed of a close-to-isobaric cooling segment in the deep crust of the hanging-wall nappe stack, an isentropic (close-to-isothermal) exhumation segment and a second close-to-isobaric cooling segment in the mid-crust.

Isochemical phase diagrams for ( a ) sample 04-6-21 from close to the botto... Available to Purchase

Published: 01 December 2009
Fig. 7. Isochemical phase diagrams for ( a ) sample 04-6-21 from close to the bottom of the Três Pontas–Varginha Nappe, and ( b ) sample 05b-6-31b from close to the top of the Três Pontas–Varginha Nappe. All assemblages also include quartz. Postulated schematic P – T path (0.15 GPa wide white
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Chondrite-normalized REE patterns (normalization after McDonough & Sun 1995). (a) REE patterns for zircon from the Socorro–Guaxupé Nappe and zircon from the top and middle of the Três Pontas–Varginha Nappe. (b) REE patterns for garnet for the same samples as shown in (a).

Chondrite-normalized REE patterns (normalization after McDonough & Sun... Available to Purchase

Published: 01 December 2009
Fig. 8. Chondrite-normalized REE patterns (normalization after McDonough & Sun 1995 ). ( a ) REE patterns for zircon from the Socorro–Guaxupé Nappe and zircon from the top and middle of the Três Pontas–Varginha Nappe. ( b ) REE patterns for garnet for the same samples as shown in ( a ).
Journal Article

Eclogite–high-pressure granulite metamorphism records early collision in West Gondwana: new data from the Southern Brasília Belt, Brazil Available to Purchase

BARRY L. RENO, MICHAEL BROWN, KATSURA KOBAYASHI, EIZO NAKAMURA, PHILIP M. PICCOLI, RUDOLPH A.J. TROUW
Published: 01 December 2009
Journal of the Geological Society (2009) 166 (6): 1013–1032.
DOI: https://doi.org/10.1144/0016-76492008-140
...Fig. 3. CL images of examples of zircons. ( a ) Zircon from the Socorro–Guaxupé Nappe (sample 04-7-1). ( b ) Zircon from leucosome close to the bottom of the Três Pontas–Varginha Nappe (sample 04-6-21). ( c ) Zircon associated with ilmenite in the middle of the Três Pontas–Varginha Nappe (sample...
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View PDF for article title, Eclogite–high-pressure granulite metamorphism records early collision in West Gondwana: new data from the Southern Brasília Belt, Brazil
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Isochemical phase diagrams constructed using the bulk compositions of samples 04-6-21 (a), 04-6-11 (b), 04-6-2 (c) and 05-6-31b (d) from the bottom, middle (two samples) and top of the Três Pontas–Varginha Nappe, respectively. All assemblages also include quartz. Compositions are in mol%.

Isochemical phase diagrams constructed using the bulk compositions of sampl... Available to Purchase

Published: 01 December 2009
Fig. 5. Isochemical phase diagrams constructed using the bulk compositions of samples 04-6-21 ( a ), 04-6-11 ( b ), 04-6-2 ( c ) and 05-6-31b ( d ) from the bottom, middle (two samples) and top of the Três Pontas–Varginha Nappe, respectively. All assemblages also include quartz. Compositions
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Images of examples of microstructures in samples from the Três Pontas–Varginha Nappe. (a) Sample 04-6-21, comprising a quartz–garnet–aluminosilicate–K-feldspar gneiss. (b) BSE image of rare intersertal plagioclase with low dihedral angles against quartz and K-feldspar. (c) Coarse-grained muscovite intersertal between K-feldspar and quartz grains in sample 04-6-2. (d) BSE image of intersertal plagioclase along grain boundaries between K-feldspar and quartz grains in sample 04-6-2. (e) Sample 05b-6-31b, comprising a quartz–garnet–biotite–K-feldspar–plagioclase–aluminosilicate–ilmenite gneiss.

Images of examples of microstructures in samples from the Três Pontas–Vargi... Available to Purchase

Published: 01 December 2009
Fig. 4. Images of examples of microstructures in samples from the Três Pontas–Varginha Nappe. ( a ) Sample 04-6-21, comprising a quartz–garnet–aluminosilicate–K-feldspar gneiss. ( b ) BSE image of rare intersertal plagioclase with low dihedral angles against quartz and K-feldspar. ( c ) Coarse
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Mesoscale features associated with fluid-present (A and B) and fluid-absent hydrate-breakdown (C and D) melting. (A) Stromatic metatexite migmatite with biotite-rich melanosomes interpreted to have formed by fluid-present melting. Floor of the Guest Hotel foyer at the China University of Geosciences, Wuhan, China; door key card for scale. (B) Patch metatexite migmatite in amphibolite interpreted to have formed by fluid-present melting; note coarser hornblende crystals associated with the in situ leucosome. From Caishixi in the Taohuayu Geoheritage Scenic Area, Taishan, Shandong Province, China; hand lens for scale. (C) Stromatic metatexite migmatite (khondalite) with pristine peritectic garnet in the leucosomes indicating loss of melt prior to retrograde cooling and final crystallization; this is interpreted to have been a fluid-absent hydrate-breakdown melting event. From Kulappara in the Kerala khondalite belt, southern India; diameter of coin ∼20 mm. (D) Mylonitized stromatic metatexite migmatite (high-pressure granulite) with pristine peritectic garnet associated with the leucosomes indicating loss of melt prior to retrograde cooling and final crystallization; this is interpreted to have been a fluid-absent hydrate-breakdown melting event. From the Lixão quarry in the Três Pontas–Varginha Nappe, southern Brasília belt, Brazil; diameter of coin ∼20 mm.

Mesoscale features associated with fluid-present (A and B) and fluid-absent... Free

Published: 01 January 2013
to have been a fluid-absent hydrate-breakdown melting event. From the Lixão quarry in the Três Pontas–Varginha Nappe, southern Brasília belt, Brazil; diameter of coin ∼20 mm.
Journal Article

Granite: From genesis to emplacement Free

Michael Brown
Journal: GSA Bulletin
Published: 01 January 2013
GSA Bulletin (2013) 125 (7-8): 1079–1113.
DOI: https://doi.org/10.1130/B30877.1
... to have been a fluid-absent hydrate-breakdown melting event. From the Lixão quarry in the Três Pontas–Varginha Nappe, southern Brasília belt, Brazil; diameter of coin ∼20 mm. ...
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