Constraints from melt inclusions and their host olivines on the petrogenesis of Oligocene-Early Miocene Xindian basalts, Chifeng area, North China Craton

Li, Hong; Zhang, Y. H.; Qian, S. J.; Liu, J. Q.; Ren, Zhong‐Yuan; Xu, Yi–Gang

doi:10.1007/s00410-012-0810-0

Cited by 37 publications

(38 citation statements)

References 141 publications

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“…6b) ratios. This is confirmed by the studies of olivine-hosted melt inclusions 39 from the south-eastern extremity of the Chifeng CFBs (119°15 0 E) erupted directly above the western edge of the stagnant Pacific slab. The melt inclusion data imply that these CFBs were mainly derived from an olivine-free pyroxenite-dominated source with high water content (4450 p.p.m.).…”

Section: Hydration Of the Mtz By Stagnant Pacific Slab Central-eastsupporting

confidence: 61%

“…This study suggests that oxygen isotopes, 39 Ar/ 40 Ar ages, and other geochemical features of the Chifeng CFBs of East Asia are correlated with distance to the western edge of the stagnant Pacific slab within the MTZ. We demonstrate that the lavas immediately above the western edge of the stagnant Pacific slab are characterized by being oversaturated in silica, having the oldest eruptive ages, the lowest olivine d 18 O values and possibly the highest fluid contents.…”

mentioning

confidence: 72%

“…40 Ar/ 39 Ar analysis. Twelve groundmass samples were dated using the stepheating 40 Ar/ 39 Ar method (Supplementary Dataset 4). 40 Ar/ 39 Ar measurements were performed at the IGGCAS, Beijing.…”

Section: Methodsmentioning

confidence: 99%

“…Twelve groundmass samples were dated using the stepheating 40 Ar/ 39 Ar method (Supplementary Dataset 4). 40 Ar/ 39 Ar measurements were performed at the IGGCAS, Beijing. To constrain the eruption age and avoid excess argon, the groundmass grains with grain size ranging from 0.2 to 0.3 mm were purified carefully under a binocular microscope to remove the visible phenocrysts and xenocrysts.…”

Section: Methodsmentioning

confidence: 99%

“…The most striking observation is that oxygen isotopes, 39 Ar/ 40 Ar ages, and other geochemical features of the Chifeng CFBs (SiO 2 , Nb, Sm/Nd, Ce/Pb, K/Ce, Tb/Yb and Sr/Ce) are correlated with distance to the western edge of the stagnant Pacific slab ( Fig. 2; Supplementary Fig.…”

Section: Hydration Of the Mtz By Stagnant Pacific Slab Central-eastmentioning

confidence: 96%

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Continental flood basalts derived from the hydrous mantle transition zone

et al. 2015

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Section: Hydration Of the Mtz By Stagnant Pacific Slab Central-eastsupporting

confidence: 61%

mentioning

confidence: 72%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Hydration Of the Mtz By Stagnant Pacific Slab Central-eastmentioning

confidence: 96%

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Continental flood basalts derived from the hydrous mantle transition zone

et al. 2015

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Magmatic recharge in continental flood basalts: Insights from the Chifeng igneous province in Inner Mongolia

Lee

Chen

Zeng

2015

Geochem Geophys Geosyst

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Eruptive sequences can be used as windows into the thermal and chemical evolution of magma chambers. We examined a continuous vertical section of the Baichahe basalt flow associated with the late Cenozoic Chifeng flood basalt in Inner Mongolia, North China. From oldest to youngest, MgO increases, K 2 O, light rare earths and other incompatible elements decrease, and Nb/La and radiogenic Pb isotopic ratios increase, all of which indicate increasing primitiveness and decreasing contribution of crustal contamination with time. The variable Pb isotope and incompatible element ratios require a component of crustal contamination, most likely of the lower crust (unradiogenic Pb, and low Ce/Pb), in the earliest lavas. Fractional crystallization can explain some of the elemental systematics, but alone cannot explain variable incompatible element ratios and Pb isotopes, nor the temporal trend to more primitive compositions. Crustal assimilation with or without fractional crystallization also cannot explain all the elemental systematics. We find instead that recharge by a primitive magma, in combination with fractional crystallization and decreasing rates of crustal assimilation, is needed to explain the observed geochemical systematics. Our observations suggest that the delivery of fresh basalt to the magma chamber must increase at rates faster than the crust can be assimilated or that the rates of crustal assimilation must decrease. However, progressive addition of primitive magma should heat up the crust and lead to more crustal assimilation. We suggest that during the initial stages of forming a magma chamber, the magma cools and develops an outer crystalline rind of mafic to ultramafic cumulates. This results in a thickening nonconvecting chemical boundary layer, which serves to insulate the magma chamber from further assimilation of crust and cooling, the latter resulting in the reduction of crystallization rates and the buffering of magma compositions at more primitive compositions. We show that certain segments of other large igneous provinces also display an evolution toward more primitive magmas with time, indicating that magmatic recharge may be a common feature of basaltic magma chambers.

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Recycled oceanic crust and marine sediment in the source of alkali basalts in Shandong, eastern China: Evidence from magma water content and oxygen isotopes

et al. 2015

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The magma water contents and cpx δ18O values in alkali basalts from the Fuyanyshan (FYS) volcano in Shandong, eastern China, were investigated by an inverse calculation based on the water content of clinopyroxene (cpx) phenocrysts, the ivAlcpx‐dependent water partitioning coefficient Dwaternormalcnormalpnormalxtrue/melt, and secondary ion mass spectrometer, respectively. The calculated water content (H2O wt.) of magma ranges from 0.58% to 3.89%. It positively correlates with heavy rare earth element concentrations and bulk rock 87Sr/86Sr ratios, and it negatively correlates with Nb/U ratios. However, it is not correlated with bulk Mg# (Mg# = 100 × Mg / (Mg + Fe)) and (La/Yb)n (n represents primitive mantle normalization). Combined with the rather homogenous distribution of water content within cpx grains, these correlations indicate that the water variations among different samples represent the original magma signature, rather than results of a shallow process, such as degassing and diffusion. The δ18O of cpx phenocrysts varies from 3.6‰ to 6.3‰ (±0.5‰, 2SD), which may be best explained by the involvement of components from the lower and upper oceanic crust with marine sediments within the mantle source. The H2O/Ce ratios of the calculated melts range from 113 to 696 and form a positive trend with bulk rock 87Sr/86Sr, which cannot be explained by the recycled Sulu eclogite or by the metasomatized lithospheric mantle. Our modeling calculation shows that the decoupling of εHf and εNd could be caused by the involvement of marine sediments. Combing the high Ba/Th ratios, positive Sr spikes, and low Ce/Pb ratios for the Fuyanshan basalts, we suggest that the hydrous nature of the FYS basalts was derived from the hydrous mantle transition zone with ancient sediments.

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Constraints from melt inclusions and their host olivines on the petrogenesis of Oligocene-Early Miocene Xindian basalts, Chifeng area, North China Craton

Cited by 37 publications

References 141 publications

Continental flood basalts derived from the hydrous mantle transition zone

Continental flood basalts derived from the hydrous mantle transition zone

Magmatic recharge in continental flood basalts: Insights from the Chifeng igneous province in Inner Mongolia

Recycled oceanic crust and marine sediment in the source of alkali basalts in Shandong, eastern China: Evidence from magma water content and oxygen isotopes

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