Sources and mobility of carbonate melts beneath cratons, with implications for deep carbon cycling, metasomatism and rift initiation

Tappe, Sebastian; Romer, Rolf L.; Stracke, Andreas; Steenfelt, Agnete; Smart, Katie A.; Muehlenbachs, Karlis; Torsvik, Trond H.

doi:10.1016/j.epsl.2017.03.011

Cited by 142 publications

(51 citation statements)

References 95 publications

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“…Geographically, carbonatite occurrences have been documented in many parts of the world with a long temporal range, spanning the Archean to the present day (Veizer, Bell, & Jansen, ; Wooley, ; Woolley & Kjarsgaard, ). Though volumetrically insignificant compared to silicate magmas, carbonatite magmas have proven useful in studying the secular evolution of the mantle through geologic time (Bell & Tilton, ; Halama, McDonough, Rudnick, & Bell, ; Hulett, Simonetti, Rasbury, & Hemming, ; Johnson, Bell, Beard, & Shultis, ; Rukhlov, Bell, & Amelin, ; Tappe et al, ). The mineralogy of carbonatites is diverse, encompassing a variety of carbonates (e.g., calcite, dolomite, ankerite, and strontianite), silicates (e.g., feldspars, pyroxenes, micas, and amphiboles), phosphates (e.g., apatite and monazite), and oxides (e.g., magnetite and pyrochlore) either as major, minor, or accessory minerals.…”

Section: Introductionmentioning

confidence: 99%

Composition and U—Pb ages of apatite in the Amba Dongar carbonatite–alkaline complex, India

et al. 2018

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The Amba Dongar carbonatite‐alkaline complex is regarded as a late phase intrusion (ca. 65 Ma) associated with Deccan volcanism. Existing age constraints on the Amba Dongar carbonatite are based on phlogopite 40Ar–39Ar plateau ages derived from carbonatite and associated alkaline rocks within the complex. We explore the utility of apatite, a common accessory mineral in Amba Dongar carbonatites, as a petrogenetic and geochronological tool to constrain further the evolution of the carbonatites. Apatite exhibits different crystal forms—from hexagonal stubby prisms to ovoid and elongate grains. Apatite occurs as cumulate and disseminated grains that are either primary, fractured, or recrystallized. SrO content is high in primary apatite (3.17 wt%) but less in recrystallized (1.90 wt%) and disseminated grains (0.47 wt%). MnO and Cl are negligible while FeO is typically low in all samples. SiO2 content is low except for a few primary grains which measure up to 1.35 wt%, correlating with high REE content. LREEs dominate the total REE budget of Amba Dongar apatite, with HREEs below EPMA detection limit in most samples. Total REE content is generally low, though some primary apatite contains up to 3.19 wt% REEs. We also report UPb apatite ages from the carbonatites analysed in situ by LA‐ICP‐MS. The data from all samples combined on a UPb Tera–Wasserburg concordia yield a lower intercept age of 65.4 ± 2.5 Ma (MSWD = 2.8, 207Pb/206Pbi = 0.8272 ± 0.0028), and the Amba Dongar carbonatites are thus interpreted to represent a phase of coeval magmatic activity with Deccan volcanism.

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Section: Introductionmentioning

confidence: 99%

Composition and U—Pb ages of apatite in the Amba Dongar carbonatite–alkaline complex, India

et al. 2018

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“…For example, Foley [2008] suggests that chemical heterogeneities at the base of the SCLM prior to rifting are an integral component. Cratonic rejuvenation at the lithosphere-asthenosphere boundary (LAB) may be in part due to carbonate melt metasomatism [Foley, 2008;Tappe et al, 2007Tappe et al, , 2008Dasgupta and Hirschmann, 2007;Tappe et al, 2017;Foley, 2011;Sleep, 2009] or rehydration from adjacent subducting slabs [Lee et al, 2008]. In these cases, weakening of the otherwise strong lithosphere can occur.…”

Section: Introductionmentioning

confidence: 99%

Decarbonation in an intracratonic setting: Insight from petrological‐thermomechanical modeling

Gonzalez

Gorczyk

2017

JGR Solid Earth

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Cratons form the stable core roots of the continental crust. Despite long‐term stability, cratons have failed in the past. Cratonic destruction (e.g., North Atlantic Craton) due to chemical rejuvenation at the base of the lithosphere remains poorly constrained numerically. We use 2‐D petrological‐thermomechanical models to assess cratonic rifting characteristics and mantle CO2 degassing in the presence of a carbonated subcontinental lithospheric mantle (SCLM). We test two tectonothermal SCLM compositions: Archon (depleted) and Tecton (fertilized) using 2 CO2 wt % in the bulk composition to represent a metasomatized SCLM. We parameterize cratonic breakup via extensional duration (7–12 Ma; full breakup), tectonothermal age, TMoho (300–600°C), and crustal rheology. The two compositions with metasomatized SCLMs share similar rifting features and decarbonation trends during initial extension. However, we show long‐term (>67 Ma) stability differences due to lithospheric density contrasts between SCLM compositions. The Tecton model shows convective removal and thinning of the metasomatized SCLM during failed rifting. The Archon composition remained stable, highlighting the primary role for SCLM density even when metasomatized at its base. In the short‐term, three failed rifting characteristics emerge: failed rifting without decarbonation, failed rifting with decarbonation, and semifailed rifting with dry asthenospheric melting and decarbonation. Decarbonation trends were greatest in the failed rifts, reaching peak fluxes of 94 × 104 kg m−3. Increased TMoho did not alter the effects of rifting or decarbonation. Lastly, we show mantle regions where decarbonation, mantle melting in the presence of carbonate, and preservation of carbonated mantle occur during rifting.

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“…The study of kimberlites and their entrained mantle cargo can provide invaluable information regarding deep Earth dynamics and melting processes in the cratonic mantle. Kimberlite melts are thought to be generated at depths ranging from 150 to 650 km, [1][2][3][4] or even deeper in the lower mantle. [5,6] Various mantle rocks entrained at different levels by ascending kimberlitic magmas can be used to constrain the composition and evolutionary processes of the lithospheric mantle beneath ancient cratons.…”

Section: Introductionmentioning

confidence: 99%

Can primitive kimberlite melts be alkali‐carbonate liquids: Composition of the melt snapshots preserved in deepest mantle xenoliths

Golovin

Sharygin

Korsakov

et al. 2019

J Raman Spectroscopy

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The study of kimberlite rocks is important as they provide critical information regarding the composition and dynamics of the continental mantle and are the principal source of diamonds. Despite many decades of research, the original compositions of kimberlite melts, which are thought to be derived from depths > 150 km, remain highly debatable due to processes that can significantly modify their composition during ascent and emplacement. Snapshots of the kimberlite‐related melts were entrapped as secondary melt inclusions hosted in olivine from sheared peridotite xenoliths from the Udachnaya‐East pipe (Siberian craton). These xenoliths originated from 180‐ to 220‐km depth and are among the deepest derived samples of mantle rocks exposed at the surface. The crystallised melt inclusions contain diverse daughter mineral assemblages (>30 mineral species), which are dominated by alkali‐rich carbonates, sulfates, and chlorides. The presence of aragonite as a daughter mineral suggests a high‐pressure origin for these inclusions. Raman‐mapping studies of unexposed inclusions show that they are dominated by carbonates (>65 vol.%), whereas silicates are subordinate (<13 vol.%). This indicates that the parental melt for the inclusions was carbonatitic. The key chemical features of this melt are very high contents of alkalis, carbon dioxide, chlorine, and sulfur and extremely low silica and water. Alkali‐carbonate melts entrapped in xenolith minerals likely represent snapshots of the primitive kimberlite melt. This composition is in contrast with the generally accepted notion that kimberlites originated as ultramafic silicate water‐rich melts. Experimental studies revealed that alkali‐carbonate melts are a very suitable diamond‐forming media. Therefore, our findings support the idea that some diamonds and kimberlite magmatism may be genetically related.

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Sources and mobility of carbonate melts beneath cratons, with implications for deep carbon cycling, metasomatism and rift initiation

Cited by 142 publications

References 95 publications

Composition and U—Pb ages of apatite in the Amba Dongar carbonatite–alkaline complex, India

Composition and U—Pb ages of apatite in the Amba Dongar carbonatite–alkaline complex, India

Decarbonation in an intracratonic setting: Insight from petrological‐thermomechanical modeling

Can primitive kimberlite melts be alkali‐carbonate liquids: Composition of the melt snapshots preserved in deepest mantle xenoliths

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