Mineralogia e Petrologia de xenólitos mantélicos da Província Kimberlitica de Juína, MT

Costa, Vicente Sergio

doi:10.11606/t.44.2013.tde-15052014-094703

“…The P-T stability fields of the peridotite samples from Rondônia are aligned near the cratonic 40 mW/m 2 geotherm in the diamond stability field, except for the partially altered peridotite xenolith VV-02. The data is distinct from those obtained by Costa (2013) in peridotite xenoliths enclosed in Juína kimberlites, as the P-T estimates are located closer to the 50 mW/m 2 geotherm (Figure 17). Considering that the Juína kimberlites are younger than the occurrences from Rondônia (80-90 Ma vs. ca.…”

Section: Geothermal Gradientscontrasting

confidence: 65%

“…Density diagrams using garnet compositions of the kimberlite fields along the Azimuth 125º Lineament from APIP (a), Rondônia (b) and Juína (c). Data compiled from: Esperança et al (1995), Costa (1996), Carvalho (1997), Zolinger (2005), Tappert et al (2006), Chaves (2008a,b), Costa (2008), Pasin (2008), Thomaz (2009), Coelho (2010), Hunt et al (2009), Andrade and Chaves (2011), Andrade (2012), Weska et al (2012), Costa (2013), Fernandes et al (2014), Hill et al (2015), Nannini (2016), Cabral Neto et al (2017b), Gervasoni et al (2022.…”

Section: Composition Of the Sclm Beneath The Azimuth 125º Lineamentmentioning

confidence: 99%

“…Despite the area's significance, publications about peridotitic, pyroxenitic and/ or eclogitic mantle xenoliths are scarce, primarily those using modern analytical techniques. Compositional data coupled with pressure and temperature calculations from garnet peridotite and eclogite samples from Rondônia and Mato Grosso states, are present in some unpublished academic thesis and dissertations (e.g., Costa 1996;Costa 2013;Weska and Svisero 2001;Nannini 2015;Cabral Neto et al 2017a), whereas significant international publications are restricted to the study of diamonds derived from the lithospheric and sublithospheric mantle (e.g., Kaminsky et al 2010;Pearson et al 2014b;Hunt et al 2009;Thomson et al 2016;Borges et al 2016;Rudloff-Grund et al 2016;Navon et al 2017). Mantle xenoliths hosted by kimberlites and kamafugites are otherwise more reported in papers from the APIP (Meyer and Svisero 1991;Leonardos et al 1993;Carlson et al 2007;Almeida et al 2014;Nannini 2015;Fernandes et al 2021).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Composition and P-T conditions of the lithospheric mantle beneath the Azimuth 125º Lineament, Northern and Southeastern Brazil: constraints from peridotite xenoliths enclosed in diamond-bearing kimberlites

Almeida¹,

Rodrigues²,

Neto³

et al. 2022

JGSB

2

0

View full text Add to dashboard Cite

We present new petrographic and chemical data together with calculated P-T equilibrium conditions of peridotite xenoliths enclosed in kimberlites from Rondônia, Northern Brazil (Cosmos-1 and Carolina-1) and Minas Gerais, Southeastern Brazil (Canastra-1) located in the Azimuth 125º Lineament. The composition of the mantle minerals is distinct in both areas, which can be related to the diversity of the lithospheric mantle beneath the southwestern portion of the Amazonian Craton and the Brasília Belt. New and compiled chemical data indicate that subcalcic G10 garnet occurs in samples from the Canastra-1 kimberlite and other occurrences of the Alto Paranaíba Igneous Province and can be related to the remnants of the Archean lithospheric mantle of the São Francisco Craton beneath the area. The garnets from Rondônia are mostly G5 (pyroxenitic) and G9 (lherzolitic) with a higher abundance of G3 (eclogitic) and G4 (pyroxenitic/eclogitic) relative to the Alto Paranaíba Igneous Province. Higher pressures and temperatures were calculated for the samples from Rondônia (40-60 kbar and 1030-1380 ºC) compared to samples from Minas Gerais (25-40 kbar and 730-1000 ºC). The peridotite xenoliths from Rondônia show P-T equilibrium conditions in the diamond stability field and can be the source of at least part of the diamond from the area. The P-T stability fields of the xenoliths from both locations are aligned close to the 40 mW/m2 geotherm. The data indicate that the cratonic 40 mW/m2 geothermal gradient in Rondônia may be related to a process of thermal relaxation of the lithospheric mantle after the Paleoproterozoic to Mesoproterozoic tectonothermal events of the southwestern Amazonian Craton until the sampling of the xenoliths by the magma in the Permian-Triassic.Composition and P-T conditions of the lithospheric mantle beneath the Azimuth 125º Lineament, Northern and Southern Brazil: constraints from peridotite xenoliths enclosed in diamond-bearing kimberlites Accepted manuscript -Uncorrected pre-proof This is a PDF file containing an unedited and non-definitive version of a manuscript that has been accepted for publication by the Journal of the Geological Survey of Brazil -JGSB, which serves to provide early visibility of the article. Being an uncorrected preproof version, errors may appear during the production process (language review, formatting and proof review), and these can affect the final content of the article and all legal disclaimers (https://jgsb.cprm.gov.br/index.php/journal/6).

show abstract

“…During the 1980s, the Juína region was the coun-try's largest producer of industrial diamonds. At its peak, some 30,000 miners produced around 400,000 carats per month (Costa, 2013). Examination of 2,200 crystals by one of the authors (DPS) in 1985 revealed that 90% were of industrial quality, gray to dark brown in appearance.…”

Section: Geologic Settingmentioning

confidence: 99%

“…Haralyi (1991) reported finding eight crystals between 49.5 and 232 ct, along with six industrial diamonds between 52 and 263 ct. According to Costa (2013), in September 1992 a garimpeiro found a 413 ct diamond in the village of Poção. Le Noan (2008) mentioned the discovery of a 452 ct "megadiamond" in alluvial deposits of the São Luiz River.…”

Section: Geologic Settingmentioning

confidence: 99%

Brazilian Diamonds: A Historical and Recent Perspective

Svisero¹,

Shigley²,

Weldon³

2017

G&G

View full text Add to dashboard Cite

Brazil, which commanded global production in the 1700s and early 1800s, has remained a continuous source of diamonds for three centuries. Even though the country represented less than 1% of world production in 2015, a number of large famous diamonds, as well as fancy-color diamonds, have originated there. The sources are primarily alluvial, with diamonds transported by and deposited along a multitude of rivers. The diamonds are found mainly by independent miners (garim eiros) in riverbeds, in unconsolidated sediments, and in compacted sedimentary conglomerates. After a century of exploration for the primary sources, some economically viable kimberlite pipes have been discovered in recent years, with one occurrence now being developed for mining. This article traces the country's fascinating diamond history before focusing on the geologic setting of the diamond occurrences, as well as the challenges and future outlook for production. The locations of the secondary deposits, principally in the states of Minas Gerais and Mato Grosso, are presented.

show abstract

Composition and P-T conditions of the lithospheric mantle beneath the Azimuth 125º Lineament, Northern and Southern Brazil: constraints from peridotite xenoliths enclosed in diamond-bearing kimberlites

Almeida¹,

Rodrigues²,

Neto³

et al. 2022

JGSB

0

View full text Add to dashboard Cite

We present new petrographic and chemical data together with calculated P-T equilibrium conditions of peridotite xenoliths enclosed in kimberlites from Rondônia, Northern Brazil (Cosmos-1 and Carolina-1) and Minas Gerais, Southeastern Brazil (Canastra-1) located in the Azimuth 125º Lineament. The composition of the mantle minerals is distinct in both areas, which can be related to the diversity of the lithospheric mantle beneath the southwestern portion of the Amazonian Craton and the Brasília Belt. New and compiled chemical data indicate that subcalcic G10 garnet occurs in samples from the Canastra-1 kimberlite and other occurrences of the Alto Paranaíba Igneous Province and can be related to the remnants of the Archean lithospheric mantle of the São Francisco Craton beneath the area. The garnets from Rondônia are mostly G5 (pyroxenitic) and G9 (lherzolitic) with a higher abundance of G3 (eclogitic) and G4 (pyroxenitic/eclogitic) relative to the Alto Paranaíba Igneous Province. Higher pressures and temperatures were calculated for the samples from Rondônia (40-60 kbar and 1030-1380 ºC) compared to samples from Minas Gerais (25-40 kbar and 730-1000 ºC). The peridotite xenoliths from Rondônia show P-T equilibrium conditions in the diamond stability field and can be the source of at least part of the diamond from the area. The P-T stability fields of the xenoliths from both locations are aligned close to the 40 mW/m2 geotherm. The data indicate that the cratonic 40 mW/m2 geothermal gradient in Rondônia may be related to a process of thermal relaxation of the lithospheric mantle after the Paleoproterozoic to Mesoproterozoic tectonothermal events of the southwestern Amazonian Craton until the sampling of the xenoliths by the magma in the Permian-Triassic.Composition and P-T conditions of the lithospheric mantle beneath the Azimuth 125º Lineament, Northern and Southern Brazil: constraints from peridotite xenoliths enclosed in diamond-bearing kimberlites Accepted manuscript -Uncorrected pre-proof This is a PDF file containing an unedited and non-definitive version of a manuscript that has been accepted for publication by the Journal of the Geological Survey of Brazil -JGSB, which serves to provide early visibility of the article. Being an uncorrected preproof version, errors may appear during the production process (language review, formatting and proof review), and these can affect the final content of the article and all legal disclaimers (https://jgsb.cprm.gov.br/index.php/journal/6).

show abstract

Mineralogia e Petrologia de xenólitos mantélicos da Província Kimberlitica de Juína, MT

Cited by 3 publications

References 12 publications

Composition and P-T conditions of the lithospheric mantle beneath the Azimuth 125º Lineament, Northern and Southeastern Brazil: constraints from peridotite xenoliths enclosed in diamond-bearing kimberlites

Composition and P-T conditions of the lithospheric mantle beneath the Azimuth 125º Lineament, Northern and Southeastern Brazil: constraints from peridotite xenoliths enclosed in diamond-bearing kimberlites

Brazilian Diamonds: A Historical and Recent Perspective

Composition and P-T conditions of the lithospheric mantle beneath the Azimuth 125º Lineament, Northern and Southern Brazil: constraints from peridotite xenoliths enclosed in diamond-bearing kimberlites

Contact Info

Product

Resources

About