Boron isotopes reveal multiple metasomatic events in the mantle beneath the eastern North China Craton

Li, Hongyan; Zhou, Zhou; Ryan, Jeffrey G.; Wei, Gangjian; Xu, Yi–Gang

doi:10.1016/j.gca.2016.08.027

Cited by 30 publications

(18 citation statements)

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“…The postrifting basalts in the NCC have been the subject of several recent studies [e.g., Zeng et al ., , ; Xu et al ., ; Sakuyama et al ., ; Liu et al ., ; Li et al ., , ]. The bulk chemical compositions of these basalts vary systematically with their SiO 2 concentrations.…”

Section: Discussionmentioning

confidence: 99%

“…Compared with the low‐SiO 2 basalts, the high‐SiO 2 basalts also have lower trace element concentrations and less fractionated REEs (lower La/Yb and Dy/Yb; Figure ), and lower ε Nd and ε Hf values (Figure b). Additionally, the high‐SiO 2 basalts are enriched in some fluid mobile elements (e.g., Sr and Ba) [ Li et al ., ]. The compositions of all these postrifting basalts are consistent with the mixing of two end‐members in terms of major and trace elements and isotopes [ Zeng et al ., , ; Li et al ., , ].…”

Section: Discussionmentioning

confidence: 99%

“…The compositions of all these postrifting basalts are consistent with the mixing of two end‐members in terms of major and trace elements and isotopes [ Zeng et al ., , ; Li et al ., , ]. The high‐SiO 2 basalts show greater contributions from an EMI‐like mantle domain than do the low‐SiO 2 basalts (Figure a) [ Zeng et al ., , ; Sakuyama et al ., ; Li et al ., , ].…”

Section: Discussionmentioning

confidence: 99%

“…The eastern North China Craton (NCC) is an ideal region for studying the different controls on the chemical composition of intracontinental basalts for three reasons: (1) numerous petrologic, tectonic, and paleoheat flow results reveal that the eastern NCC experienced significant lithospheric thinning and thickening events during the Cenozoic [Xu, 2001;Hu et al, 2001;Qi and Yang, 2010;Li et al, 2014]; (2) these lithospheric changes coincided with long-term intracontinental basaltic magmatism both within and along the margins of the NCC, potentially recording these changes [Wu et al, 2005;Zeng et al, 2010Zeng et al, , 2011Li et al, 2014Li et al, , 2016a; and (3) the Cenozoic basalts in the eastern NCC appear to record mixing of isotopically enriched and depleted materials in varying proportions [Zeng et al, 2010[Zeng et al, , 2011Xu et al, 2012a;Li et al, 2014Li et al, , 2016aLi et al, , 2016b].…”

Section: Sr-nd-hf Isotopesmentioning

confidence: 99%

“…The postrifting suite of basalts includes the 21-0.3 Ma alkali olivine basalts, basanites, and nephelinites in Shandong. Although Miocene tholeiites from the Jiyang Sag have 40 Ar/ 39 Ar ages of~23 Ma, right on the boundary between the rifting and postrifting events of the BBB, they are treated together with the postrifting basalts in the following discussion for these reasons: (1) the rifting-stage basalts were erupted under conditions of strong asthenospheric upwelling in the mantle in association with The postrifting basalts in the NCC have been the subject of several recent studies [e.g., Zeng et al, 2010Zeng et al, , 2011Xu et al, 2012b;Sakuyama et al, 2013;Liu et al, 2015;Li et al, 2016aLi et al, , 2016b. The bulk chemical compositions of these basalts vary systematically with their SiO 2 concentrations.…”

Section: Summary Of the Geochemistry Of The Postrifting Basalts: Miximentioning

confidence: 99%

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Evolution of the mantle beneath the eastern North China Craton during the Cenozoic: Linking geochemical and geophysical observations

Ryan

et al. 2017

JGR Solid Earth

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Recent discoveries related to the geochemistry of Cenozoic basalts and the geophysics of the deep mantle beneath eastern Eurasia make it possible to place constraints on the relationship between the seismic tomography of subcontinental mantle domains and their geochemical heterogeneities. Basalts with ocean island basalt‐like trace elements erupted during (56–23 Ma) and after (≤23 Ma) rifting of the eastern North China Craton (NCC) show evidence for the mixing of an isotopically depleted source and an EMI (Enriched mantle type I) pyroxenitic mantle. NCC rifting‐stage basalts exhibit anomalously low MgO and Fe2O3T and high SiO2 and Al2O3, as well as low Dy/Yb and Y/Yb and high εHf at a given εNd, as compared to the postrifting basalts. Temporal compositional variations and their association with basin subsidence indicate that heterogeneity in the eastern NCC asthenospheric mantle is the primary driver for intraplate magmatism in this region. The specific magmatic sources shifted in terms of depth, related to lithospheric thinning and thickening in the eastern NCC. The NCC EMI mantle domain most likely developed due to ancient events, is persistent through time, and is not related to dehydration of the stagnant Pacific slab in the mantle transition zone. Based on the chemical signatures of postrifting basalts, contributions from the Pacific slab are likely to be carbonatite rich. Mantle metasomatism by carbonatite melts from the Pacific slab and the interaction of these melts at shallower depths with EMI pyroxenitic mantle domains to trigger melting are contributors to the observed low P wave velocity zone beneath eastern Eurasia.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Sr-nd-hf Isotopesmentioning

confidence: 99%

Section: Summary Of the Geochemistry Of The Postrifting Basalts: Miximentioning

confidence: 99%

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Evolution of the mantle beneath the eastern North China Craton during the Cenozoic: Linking geochemical and geophysical observations

Ryan

et al. 2017

JGR Solid Earth

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Light Stable Isotopic Compositions of Enriched Mantle Sources: Resolving the Dehydration Paradox

Dixon

Bindeman

Kingsley

et al. 2017

Geochem Geophys Geosyst

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Volatile and stable isotope data provide tests of mantle processes that give rise to mantle heterogeneity. New data on enriched mid‐oceanic ridge basalts (MORB) show a diversity of enriched components. Pacific PREMA‐type basalts (H2O/Ce = 215 ± 30, δDSMOW = −45 ± 5 ‰) are similar to those in the northern Atlantic (H2O/Ce = 220 ± 30; δDSMOW = −30 to −40 ‰). Basalts with EM‐type signatures have regionally variable volatile compositions. Northern Atlantic EM‐type basalts are wetter (H2O/Ce = 330 ± 30) and have isotopically heavier hydrogen (δDSMOW = −57 ± 5 ‰) than northern Atlantic MORB. Southern Atlantic EM‐type basalts are damp (H2O/Ce = 120 ± 10) with intermediate δDSMOW (−68 ± 2 ‰), similar to δDSMOW for Pacific MORB. Northern Pacific EM‐type basalts are dry (H2O/Ce = 110 ± 20) and isotopically light (δDSMOW = −94 ± 3 ‰). A multistage metasomatic and melting model accounts for the origin of the enriched components by extending the subduction factory concept down through the mantle transition zone, with slab temperature a key variable. Volatiles and their stable isotopes are decoupled from lithophile elements, reflecting primary dehydration of the slab followed by secondary rehydration, infiltration, and re‐equilibration by fluids derived from dehydrating subcrustal hydrous phases (e.g., antigorite) in cooler, deeper parts of the slab. Enriched mantle sources form by addition of <1% carbonated eclogite ± sediment‐derived C‐O‐H‐Cl fluids to depleted mantle at 180–280 km (EM) or within the transition zone (PREMA).

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B isotopes of Carboniferous‐Permian volcanic rocks in the Tuha basin mirror a transition from subduction to intraplate setting in Central Asian Orogenic Belt

Liu

Wei

et al. 2016

JGR Solid Earth

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Controversies remain as to the Permian tectonic setting in the Central Asian Orogenic Belt (CAOB), in particular, regarding the triggering of Permian magmatism. To address this issue, we carried out a geochemical study on Dananhu volcanics from the Tuha basin, southwestern CAOB. 40Ar/39Ar analyses for feldspar separates yield a Carboniferous age of 321.2 ± 9.8 Ma for the andesites and a Permian age of 278.9 ± 4.2 Ma for the basalts. Both the andesites and basalts geochemically resemble subduction‐related magmas in aspects of their trace element and Sr‐Nd‐Pb isotopic composition, but they may differ in petrogenesis. The andesites are typical adakites. Their high Cr and Ni contents, and low heavy rare earth element contents, and positive correlation between B/Nb ratios and δ11B values suggest that they were generated by interaction between slab‐derived melts/fluids and the mantle wedge. The Permian basalts are subdivided into two subgroups: alkali and tholeiitic basalts. High Ba/La and Ba/Zr ratios indicate that the source of the alkali basalts has been metasomatized by fluids/melts derived from altered oceanic crust. In contrast, a volatile‐free source metasomatized by sediment‐derived fluids/melts is inferred for the tholeiitic basalts given their high Th/Zr and Th/Ce ratios. Negative correlation between B/Nb and δ11B for the Permian basalts imply that the arc signatures were imposed by previous subduction events, and no direct slab‐derived fluids/melts participated in their petrogenesis. These geochemical characteristics alongside regional geologic records collectively suggest a tectonic shift in the southwestern CAOB from subduction‐related setting during the Late Carboniferous to an intraplate setting during the Early Permian.

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Boron isotopes reveal multiple metasomatic events in the mantle beneath the eastern North China Craton

Cited by 30 publications

References 101 publications

Evolution of the mantle beneath the eastern North China Craton during the Cenozoic: Linking geochemical and geophysical observations

Evolution of the mantle beneath the eastern North China Craton during the Cenozoic: Linking geochemical and geophysical observations

Light Stable Isotopic Compositions of Enriched Mantle Sources: Resolving the Dehydration Paradox

B isotopes of Carboniferous‐Permian volcanic rocks in the Tuha basin mirror a transition from subduction to intraplate setting in Central Asian Orogenic Belt

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