Origin of low δ 26 Mg Cenozoic basalts from South China Block and their geodynamic implications

Huang, Junhua; Li, Qiuli; Xiao, Yilin; Ke, Shaoyong; Li, Wang-Ye; Tian, Ye

doi:10.1016/j.gca.2015.04.054

Cited by 155 publications

(66 citation statements)

References 105 publications

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“…Recently, the light Mg isotopic compositions (d 26 Mg = À0.60 to À0.35‰) of the <110 Ma basalts from the North China Craton (NCC) and South China Block (SCB) have been attributed to the interaction between mantle peridotites and isotopically light carbonate melts derived from the subducted Pacific slab (Yang et al, 2012;Huang et al, 2015). This relationship is supported by seismic tomographic observations that suggest the stagnant Pacific slab existed in the mantle transition zone under eastern China (Huang and Zhao, 2006;Zhao et al, 2011).…”

Section: Introductionmentioning

confidence: 92%

“…1). A considerable number of studies on these basalts have been conducted since the 1980s (e.g., Zhou and Armstrong, 1982;Peng et al, 1986;Zhou et al, 1988;Song et al, 1990;Zhi et al, 1990;Liu et al, 1994;Zou et al, 2000;Zhang et al, 2003Zhang et al, , 2009Xu et al, 2005;Tang et al, 2006;Yang and Li, 2008;Chen et al, 2009;Zeng et al, 2010Zeng et al, , 2011Wang et al, 2011;Yang et al, 2012;Huang et al, 2015). The Cenozoic basalts in NE China, including Wudalianchi, Erkeshan, Keluo and Xiaogulihe volcanic fields, are located on the northern margin of the Songliao graben, encompassing an area of >1400 km 2 (Fig.…”

Section: Geological Background and Sample Descriptionmentioning

confidence: 99%

“…Wudalianchi and Erkeshan are denoted by red circles. The yellow triangles represent the locations of the previously reported low d 26 Mg basalts from the North China Craton and the South China Block (Yang et al, 2012;Huang et al, 2015). The dark grey area is the distribution of the low d 26 Mg basalts, indicating a large-scale light Mg isotope anomaly in the mantle beneath eastern China.…”

Section: Geological Background and Sample Descriptionmentioning

confidence: 99%

“…Several models may explain the mantle source: (1) subcontinental lithospheric mantle (SCLM) enriched by past metasomatism during the Proterozoic (Zhang et al, 1995(Zhang et al, , 1998(Zhang et al, , 2000, likely phlogopite-bearing garnet peridotites (Zou et al, 2003;Sun et al, 2015); (2) shallow asthenosphere containing Sun and McDonough (1989). The NCC and SCB basalt data are from Tang et al (2006) and Huang et al (2015), respectively. The arrow represents metasomatism by fluids from sediments, which elevates Ba/Th and decreases Ce/Pb.…”

Section: Geological Background and Sample Descriptionmentioning

confidence: 99%

“…The Wudalianchi and Erkeshan basalts are from Chu et al (2013). The NCC and SCB basalts are from Zhang et al (2003), Tang et al (2006) and Huang et al (2015). fragments of delaminated SCLM due to the Sr-Nd-Pb-Hf isotopic characteristics resembling a DMM-EMI array (Choi et al, 2006); (3) mixed FOZO (Focal Zone; Hart et al, 1992) and LoMu (low U/Pb; Douglass et al, 1999) mantle sources (Chen et al, 2007); (4) mantle transition zone metasomatized by K-rich sediment-derived fluids approximately 1.5 Ga ago, due to the stagnation of an ancient slab (Kuritani et al, 2013) and (5) SCLM metasomatized by delaminated lower continental crust based on low Ce/Pb ratios and unradiogenic Pb isotopic compositions (Chu et al, 2013).…”

Section: Geological Background and Sample Descriptionmentioning

confidence: 99%

See 4 more Smart Citations

Origin of low δ26Mg basalts with EM-I component: Evidence for interaction between enriched lithosphere and carbonated asthenosphere

Tian

Yang

et al. 2016

Geochimica et Cosmochimica Acta

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This study presents stable Mg isotopic data for Cenozoic potassic basalts from Wudalianchi and Erkeshan in northeastern China to determine the interactions between upwelling carbonated asthenosphere and enriched lithospheric mantle. Although the Wudalianchi and Erkeshan basalts have variable MgO contents of 4.45 to 9.47 wt.%, they exhibit a homogeneous Mg isotopic composition with d 26 Mg values ranging from À0.57‰ to À0.46‰ and averaging À0.51 ± 0.06‰ (2SD, n = 18). This Mg isotopic composition is lighter than that of the average mantle (d 26 Mg = À0.25 ± 0.07‰) but similar to late Cretaceous (<110 Ma) and Cenozoic basalts from the North China Craton and the South China Block (d 26 Mg = À0.60 to À0.35‰). The high CaO/Al 2 O 3 and Ba/Rb, and low Hf/Hf * ratios of the Wudalianchi and Erkeshan basalts are typical characteristics of carbonatitic metasomatism, suggesting that the light Mg isotopic composition could derive from involvement of recycled sedimentary carbonates in the mantle source. The high Dy/Er ratios (2.55 to 2.75) and excess of 230 Th ( 230 Th/ 238 U = 1.24 to 1.33) suggest presence of garnet in a relatively deep mantle source. Additionally, the seismic tomographic observations show the existence of the stagnant Pacific slab in the mantle transition zone (410-660 km) under eastern China. This carbonated mantle source should be located in the asthenosphere. However, compared to other low d 26 Mg basalts from eastern China with MORB-like Sr-Nd-Pb isotopic compositions and OIB-like trace element features, the Wudalianchi and Erkeshan basalts exhibit EM-I Sr-Nd-Pb isotopic compositions combined with high SiO 2 , Ba, K, Pb and LREE contents, high Ba/Th and low Ce/Pb ratios. These geochemical features require a contribution from another mantle source, most likely an EM-I lithospheric mantle. Therefore, an asthenosphere-lithosphere interaction model is proposed for determine the origin of the Wudalianchi and Erkeshan basalts. The original melt was derived from partial melting of the carbonated asthenospheric mantle that was metasomatized by carbonate melt from the stagnant Pacific slab in the mantle transition zone. This ascending melt with a low d 26 Mg signature subsequently interacted with the EM-I lithospheric mantle. The interaction dissolved pyroxene and crystallized olivine, releasing LILE, REE, Sr and Pb from dissolved minerals into the melt. Simultaneously, Mg was inherited by newly formed olivine. Therefore, this interaction modified the trace elements and the Sr-Nd-Pb isotopic compositions of the melt toward EM-I geochemical features but preserved the light Mg isotope signatures.

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Section: Introductionmentioning

confidence: 92%

Section: Geological Background and Sample Descriptionmentioning

confidence: 99%

Section: Geological Background and Sample Descriptionmentioning

confidence: 99%

Section: Geological Background and Sample Descriptionmentioning

confidence: 99%

Section: Geological Background and Sample Descriptionmentioning

confidence: 99%

See 3 more Smart Citations

Origin of low δ26Mg basalts with EM-I component: Evidence for interaction between enriched lithosphere and carbonated asthenosphere

Tian

Yang

et al. 2016

Geochimica et Cosmochimica Acta

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Trace element and Sr isotope records of multi‐episode carbonatite metasomatism on the eastern margin of the North China Craton

Deng

Liu

Zong

et al. 2017

Geochem Geophys Geosyst

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Lherzolite xenoliths entrained in the Changle Cenozoic basalts were analyzed to infer mantle process beneath the eastern block of the North China Craton. These xenoliths were classified into two types. Clinopyroxenes (Cpx) in the type-1 xenoliths are strongly enriched in large ion lithophile elements and light rare earth elements (LREE) but depleted in high field-strength elements and heavy rare earth elements, and show high Ca/Al, Zr/Hf, and (La/Yb) N ratios but low Ti/Eu ratios. These features indicate that they were crystallized from a carbonatitic melt. Cpx in the type-2 xenoliths are mostly characterized by a chemical zonation, that is, LREE and Sr contents and (La/Yb) N and Eu/Ti ratios gradually increase from the cores to the rims. Some fresh cores preserve the original signatures of the depleted mantle. These observations indicate partial modification of pre-existing Cpx by carbonatite metasomatism. Two episodes of metasomatism were identified based on Sr isotopic compositions of Cpx and carbonate inclusions within olivines. Both the carbonate inclusions and Cpx cores in the type-2 xenoliths have relatively high 87 Sr/ 86 Sr ratios (>0.7033), suggesting metasomatism due to CO 2 -rich silicate melt derived from the recycled oceanic crust. However, low 87 Sr/ 86 Sr ratios of Cpx rims in the type-2 xenoliths suggest a late stage of metasomatism by a low-87 Sr/ 86 Sr carbonatitic melt (<0.7024), which might have been caused by upwelling of the asthenosphere mantle. Such multiple metasomatism could have played an important role in changing the chemical composition of mantle from refractory and depleted to fertile and enriched.

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Geodynamics of paleo‐Pacific plate subduction constrained by the source lithologies of Late Mesozoic basalts in southeastern China

Zeng

et al. 2016

Geophysical Research Letters

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Widespread Late Mesozoic volcanic magmatism in southeastern China is generally thought to represent products in response to the subduction of paleo‐Pacific plate; however, it remains unclear when this process began to affect the mantle and the related magmatism. Here we present a systematic study on the source lithology of Late Mesozoic basalts in this area to highlight a link between lithological variations of mantle and subduction process of paleo‐Pacific plate. Late Mesozoic basalts can be subdivided into four groups based on their erupted ages: 178~172 Ma, approximately 150 Ma, 137~123 Ma, and 109~64 Ma. The primary source lithology of these rocks is pyroxenite rather than peridotite, and this mafic lithology can be formed by either ancient or young recycled crustal components. Notably, the source lithology of the approximately 150 Ma and 137~123 Ma basalts is primarily SiO2‐rich pyroxenite, and the former is carbonated. The discovery of carbonated, SiO2‐rich pyroxenite reflects the influence of a recently recycling event in the mantle. The subduction of paleo‐Pacific plate is the most appropriate candidate and can be responsible for the mantle‐derived magmatism after approximately 150 Ma in southeastern China. Therefore, we suggest a paleo‐Pacific slab rollback with increased dip angle as a possible model to control the lithological variations of Late Mesozoic mantle beneath southeastern China.

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Origin of low δ 26 Mg Cenozoic basalts from South China Block and their geodynamic implications

Cited by 155 publications

References 105 publications

Origin of low δ26Mg basalts with EM-I component: Evidence for interaction between enriched lithosphere and carbonated asthenosphere

Origin of low δ26Mg basalts with EM-I component: Evidence for interaction between enriched lithosphere and carbonated asthenosphere

Trace element and Sr isotope records of multi‐episode carbonatite metasomatism on the eastern margin of the North China Craton

Geodynamics of paleo‐Pacific plate subduction constrained by the source lithologies of Late Mesozoic basalts in southeastern China

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