An exotic Cretaceous kimberlite linked to metasomatized lithospheric mantle beneath the southwestern margin of the São Francisco Craton, Brazil

Carvalho, Luísa Diniz Vilela de; Jalowitzki, Tiago; Scholz, Ricardo; Gonçalves, Gonçalo; Rocha, Marcelo Peres; Pereira, Rogério Silvestre; Lana, Cristiano; Castro, Marco Paulo de; Queiroga, Gláucia Nascimento; Fuck, Reinhardt A.

doi:10.1016/j.gsf.2021.101281

Cited by 13 publications

(5 citation statements)

References 125 publications

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“…The data reduction package JEOL/EPMA was used to perform the calibration, overlap correction and quantification (see Carvalho et al . 2022 for more details on analytical conditions).…”

Section: Origin Of the Khan River And Bear Lake Titanitementioning

confidence: 99%

“…Data collection employed 20 s counting times for both peak and background for all elements except F, for which counting times were 150 s for both on peak and background. The data reduction package JEOL/EPMA was used to perform the calibration, overlap correction and quantification (see Carvalho et al 2022 for more details on analytical conditions).…”

Section: Backscattered Electron Imaging and Electron Probe Microanalysismentioning

confidence: 99%

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Khan River and Bear Lake: Two Natural Titanite Reference Materials for High‐Spatial Resolution U‐Pb Microanalysis

Mazoz

Gonçalves

Lana

et al. 2022

Geostandard Geoanalytic Res

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The Khan River (Namibia) and Bear Lake (Canada) titanites are investigated as potential reference materials (RM) for LA‐ICP‐MS applications. The Bear Lake titanite is texturally and compositionally homogeneous. The Khan River titanite is texturally heterogeneous and characterised by variable trace element compositions and total rare earth element contents. However, both titanites have consistent U‐Pb and Nd‐isotope ratios. U‐Pb isotope dilution‐thermal ionisation mass spectrometry analyses yielded Pbc‐uncorrected intercept ages of 516.3 ± 1.3 Ma (2s, n = 5, MSWD = 2.4) and 1067.81 ± 0.74 Ma (2s, n = 4, MSWD = 0.35) for Khan River and Bear Lake titanites, respectively. Multiple U‐Pb LA‐SF/MC‐ICP‐MS analyses gave consistent Pbc‐uncorrected intercept ages for both, Khan River (517 ± 1/5 Ma, 2s, n = 262, MSWD = 1.5) and Bear Lake (1070 ± 1/11 Ma, 2s, n = 325, MSWD = 0.88). U‐Pb SHRIMP analyses on the same material returned identical (within uncertainty) ages. Khan River and Bear Lake gave internally consistent solution MC‐ICP‐MS 143Nd/144Nd ratios of 0.511587 ± 0.000027 (2s, n = 2) and 0.512321 ± 0.000004 (2s, n = 2), respectively. The 143Nd/144Nd ratios via solution‐MC‐ICP‐MS and LA‐ICP‐MS all agree within uncertainty and suggest that both titanites can be used as RMs for Nd‐isotope analyses.

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“…The data reduction package JEOL/EPMA was used to perform the calibration, overlap correction and quantification (see Carvalho et al . 2022 for more details on analytical conditions).…”

Section: Origin Of the Khan River And Bear Lake Titanitementioning

confidence: 99%

Section: Backscattered Electron Imaging and Electron Probe Microanalysismentioning

confidence: 99%

Khan River and Bear Lake: Two Natural Titanite Reference Materials for High‐Spatial Resolution U‐Pb Microanalysis

Mazoz

Gonçalves

Lana

et al. 2022

Geostandard Geoanalytic Res

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“…We next evaluated the spatial and temporal relationship between continental breakup and kimberlite magmatism, taking Mesozoic Africa and South America (affected by the same Gondwana breakup episode) as a case study where data confidence (e.g., kimberlite ages and rifting history) is high. We utilized the same kimberlite database 6 as in our global analysis above, adding several radiometric ages for the Brazil region 64,65,66,67,68 . Paleogeographic reconstructions were obtained from the open-source plate tectonic modelling software, GPlates 23,69 .…”

Section: Spatial and Temporal Links Between Breakup And Kimberlitesmentioning

confidence: 99%

Rift-induced disruption of cratonic keels drives kimberlite volcanism

Gernon

Jones

Brune

et al. 2023

Nature

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Kimberlites are volatile-rich, occasionally diamond-bearing magmas that have erupted explosively at Earth’s surface in the geologic past1–3. These enigmatic magmas, originating from depths exceeding 150 km in Earth’s mantle1, occur in stable cratons and in pulses broadly synchronous with supercontinent cyclicity4. Whether their mobilization is driven by mantle plumes5 or by mechanical weakening of cratonic lithosphere4,6 remains unclear. Here we show that most kimberlites spanning the past billion years erupted about 30 million years (Myr) after continental breakup, suggesting an association with rifting processes. Our dynamical and analytical models show that physically steep lithosphere–asthenosphere boundaries (LABs) formed during rifting generate convective instabilities in the asthenosphere that slowly migrate many hundreds to thousands of kilometres inboard of rift zones. These instabilities endure many tens of millions of years after continental breakup and destabilize the basal tens of kilometres of the cratonic lithosphere, or keel. Displaced keel is replaced by a hot, upwelling mixture of asthenosphere and recycled volatile-rich keel in the return flow, causing decompressional partial melting. Our calculations show that this process can generate small-volume, low-degree, volatile-rich melts, closely matching the characteristics expected of kimberlites1–3. Together, these results provide a quantitative and mechanistic link between kimberlite episodicity and supercontinent cycles through progressive disruption of cratonic keels.

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“…During the Neoproterozoic, the region went through a phase of compression, which culminated in the development of the Brasiliano orogenic belts on the margins of the São Francisco‐Congo Craton (Almeida et al., 2000). In the Upper Cretaceous, during Gondwana break‐up, magmatism occurred but was restricted to the (southern) border with the Paraná Basin (e.g., da Silva et al., 2008; Carvalho et al., 2022; Hackspacher et al., 2007). Hence, we propose that the metasomatism observed in the shallow São Francisco lithosphere could be due to its Paleoproterozoic assembly, with a possible further contribution from Neoproterozoic orogenic events along the Craton's margins.…”

Section: Discussionmentioning

confidence: 99%

Thermo‐Compositional Structure of the South American Platform Lithosphere: Evidence of Stability, Modification, and Erosion

Altoe

Goes

Assumpção

2022

Geochem Geophys Geosyst

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Introduction MotivationCratons are the stable continental cores formed during the Precambrian. Their formation, evolution and long-term stability is still debated (e.g., C.-T. A. Lee et al., 2011;van Hunen & Moyen, 2012;Sleep, 2005). Mapping lithospheric temperatures and compositional heterogeneity may shed light on their formation, evolution, and long-term stability. Cratonic mantle lithosphere is often described as relatively homogeneous, characterized by thick and high-wavespeed roots (Schaeffer & Lebedev, 2015), low surface heat flow (Cooper et al., 2004), and being approximately neutrally buoyant due to iron depletion as a result of melt extraction (Griffin et al., 2009;Jordan, 1978). However, recent studies have found heterogeneities within and between cratonic keels. S-to-P receiver function studies in cratonic regions have revealed sharp negative and/or positive wavespeed-depth gradients in the lithospheric mantle. The low or high wavespeed layers needed to explain such gradients have been

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An exotic Cretaceous kimberlite linked to metasomatized lithospheric mantle beneath the southwestern margin of the São Francisco Craton, Brazil

Cited by 13 publications

References 125 publications

Khan River and Bear Lake: Two Natural Titanite Reference Materials for High‐Spatial Resolution U‐Pb Microanalysis

Khan River and Bear Lake: Two Natural Titanite Reference Materials for High‐Spatial Resolution U‐Pb Microanalysis

Rift-induced disruption of cratonic keels drives kimberlite volcanism

Thermo‐Compositional Structure of the South American Platform Lithosphere: Evidence of Stability, Modification, and Erosion

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