Mantle Heterogeneity and Melting Processes in the South China Sea: Thermal and Melting Models Constrained by Oceanic Crustal Thickness and Basalt Geochemistry

Zhang, Xubo; Lin, Jian; Behn, M. D.

doi:10.1029/2020jb020735

Cited by 4 publications

(2 citation statements)

References 102 publications

(305 reference statements)

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“…The MORBs of the East sub-basin (U1431) do not have unradiogenic Pb isotopic compositions and hence it has been suggested that the role of lower continental crust is insignificant here (Li et al, 2008;Pautot et al, 1986;Zhang et al, 2018Zhang et al, , 2021. Based on magnetic anomalies, it was inferred that the central East Sub-basin developed within a pre-existing ocean, whereas the Southwest sub-basin evolved from a continental rift and therefore had a more continental signature (Li et al, 2008).…”

Section: Ancient Cratonic Lower Continental Crustal Materials In the ...mentioning

confidence: 99%

“…As a continental marginal sea, the SCS has experienced the full Wilson Cycle including continental rifting and breakup, seafloor spreading and subduction (Ding et al, 2018;Li et al, 2015;Taylor & Hayes, 1983) and the upper mantle is proposed to be contaminated by delaminated lower continental crustal materials (Li et al, 2008;Pautot et al, 1986;Zhang et al, 2018Zhang et al, , 2021. Lower continental crustal materials are considered to have unradiogenic Pb isotopes (O'Nions et al, 1979).…”

Section: Ancient Cratonic Lower Continental Crustal Materials In the ...mentioning

confidence: 99%

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Highly Unradiogenic Pb Isotopes Revealed by Plagioclase‐Hosted Melt Inclusions in E‐MORB From the South China Sea

Zhang

Wilde

et al. 2023

JGR Solid Earth

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Mid‐ocean ridge basalts (MORBs) can record heterogeneity of the upper mantle. Early crystallized minerals and their melt inclusions commonly record greater isotopic variability than whole‐rocks and are powerful tools to investigate the mantle source. In this study, we develop a new in situ Pb analytical protocol for Pb‐poor materials (sub‐ppm level) and apply it to the plagioclase‐hosted melt‐inclusions from IODP Expedition 349 Site U1433, South China Sea (SCS). Together with element mapping, in situ major and trace element analyzes and in situ Sr isotopes of plagioclase phenocrysts, we show that unlike the low and uniform whole‐rock 87Sr/86Sr ratios, the plagioclase phenocrysts record extreme Sr isotopic heterogeneity. Strontium isotopic heterogeneity is observed between crystals even in a single thin section. Based on the high an contents of plagioclase phenocrysts and high Mg# values of their melt inclusions, we propose they crystallized early in the magma chamber and were most likely formed in different batches of mantle‐derived melts. The plagioclase‐hosted melt inclusions show highly variable Pb isotopes, exhibiting a typical linear variation in 207Pb/204Pb versus 206Pb/204Pb. Such a mixing trend indicates an end‐member with highly unradiogenic Pb isotopes. The LREE enrichment and negative correlations between La/Sm and Pb isotopes of the melt inclusions, indicate that ancient cratonic lower continent crustal materials, with low time‐integrated U/Pb ratios, are likely present in the sub‐ridge mantle of the southwest Sub‐basin, SCS.

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Section: Ancient Cratonic Lower Continental Crustal Materials In the ...mentioning

confidence: 99%

Section: Ancient Cratonic Lower Continental Crustal Materials In the ...mentioning

confidence: 99%

Highly Unradiogenic Pb Isotopes Revealed by Plagioclase‐Hosted Melt Inclusions in E‐MORB From the South China Sea

Zhang

Wilde

et al. 2023

JGR Solid Earth

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Revisiting the South China Sea MORBs: Mg isotope and whole-rock geochemical constraints

Hong,

Wu,

et al. 2023

Marine Geology

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Modification of Along‐Ridge Topography and Crustal Thickness by Mantle Plume and Oceanic Transform Fault at Ultra‐Slow Spreading Mohns Ridge

Zhang,

Zhang

et al. 2023

Geophysical Research Letters

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The mantle plumes modify geophysical and geochemical features along and across mid‐ocean ridges. Despite abundant studies of plume‐ridge interaction, few geodynamic studies focus on the Arctic Ocean. The Jan Mayen Hotspot is located at the southern end of the Mohns Ridge and offset by the Jan Mayen Transform Fault, which creates an ideal area to study plume‐ridge‐transform fault interaction at the ultra‐slow spreading ridge. Through analyzing geophysical observations, we revealed that the M factor and crustal thickness decrease and the axial relief increases northeastward along the Mohns Ridge within a distance of ∼370 km to the Jan Mayen Hotspot. Combined with modeling results, the properties of the Jan Mayen plume were estimated, which has a diameter of 75 km, a temperature anomaly of 100°C, and a buoyancy flux of 0.22 Mg/s. Additionally, our model results indicate that the along‐ridge dispersion of plume is slightly enhanced by the transform fault.

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Mantle Heterogeneity and Melting Processes in the South China Sea: Thermal and Melting Models Constrained by Oceanic Crustal Thickness and Basalt Geochemistry

Cited by 4 publications

References 102 publications

Highly Unradiogenic Pb Isotopes Revealed by Plagioclase‐Hosted Melt Inclusions in E‐MORB From the South China Sea

Highly Unradiogenic Pb Isotopes Revealed by Plagioclase‐Hosted Melt Inclusions in E‐MORB From the South China Sea

Revisiting the South China Sea MORBs: Mg isotope and whole-rock geochemical constraints

Modification of Along‐Ridge Topography and Crustal Thickness by Mantle Plume and Oceanic Transform Fault at Ultra‐Slow Spreading Mohns Ridge

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