Xenolith evidence for polybaric melting and stratification of the upper mantle beneath South China

Xu, Yi–Gang; Sun, Min; Yan, Wen; Liu, Y; Huang, Xiaolong; Chen, X.M

doi:10.1016/s1367-9120(01)00087-6

Cited by 68 publications

(52 citation statements)

References 60 publications

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“…The enriched lithospheric mantle beneath South China commonly displays HFSE depletion [10,84], in striking contrast with the HFSE enrichment in Cenozoic basalts from this area. Given the fact that the lithosphere is relatively thin underneath the SCS [85], and it may have been thinned during the period of eruption [2], it is suggested that the EM2 component in basalts from the SCS and its surroundings is not related to recycling of lithospheric mantle.…”

Section: Hainan Mantle Plume and Its Link With The Opening Of The Soumentioning

confidence: 87%

“…Moreover, the trace element composition of peridotite xenoliths suggests a polybaric melting experienced by the upper mantle in this region [10], indicating the peak extension of the lithosphere during the early Cenozoic. In addition, Yb contents in 40-50 Ma magmas are higher than those in ~20 Ma basalts (Figure 7), consistent with a gradual increase in origin depth of magmas, probably due to waning of regional extension towards the mid-Cenozoic.…”

Section: The Opening Of the South China Seamentioning

confidence: 87%

“…Volcanic pipes of ~35 Ma occur in Qiling, eastern Guangdong Province. These pipes carry a large amount of mantle-derived xenoliths, which have attracted much attention for studying the thermal state, lithospheric structure, and processes of the upper mantle [10,61,62].…”

Section: Previous Studies On Volcanic Rocks In the South China Sea Anmentioning

confidence: 99%

“…Named the Hainan mantle plume, it may be responsible for the wide-spread Cenozoic alkali basalts in the Leizhou Peninsula, Hainan Island, SCS, and Indochina, affecting an area of over 4×10 6 km 2 (Figure 1) [8]. If the Hainan mantle plume does exist, the relevant questions include the following: Was the plume activity responsible for the opening of [9][10][11][12]). The distribution of syn-spreading magmas is inferred from seafloor magnetic anomalies [1,11].…”

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confidence: 99%

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Opening and evolution of the South China Sea constrained by studies on volcanic rocks: Preliminary results and a research design

et al. 2011

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The South China Sea (SCS) is characterized by abundant seamounts, which provide important information about the evolution of the SCS and related deep processes. Cenozoic volcanism in the SCS and its surroundings comprises three stages relative to the spreading of the SCS: pre-spreading (>32 Ma), syn-spreading (32-16 Ma), and post-spreading (<16 Ma). The pre-spreading magmatism predominantly occurs on the northern margin of the SCS and in South China coastal areas and shows a bi-modal affinity. The syn-spreading magmatic activity was very limited on the periphery of the SCS, but may be concentrated in the SCS. However, seafloor samples of this stage are not available yet because of overlying thick sedimentary deposits. Post-spreading magmatism is widespread in the central and southwest sub-basins of the SCS, Hainan Island, Leizhou Peninsula, Thailand, and Vietnam. These are mainly alkali basalts with subordinate tholeiites, and display OIB-type geochemical characteristics. The Dupal isotope anomaly and presence of high-magnesian olivine phenocrysts suggests their possible derivation from the Hainan mantle plume. The temporal and spatial distribution of Cenozoic volcanism in the SCS and its surroundings may be accounted for either by plate stress re-organization before and after SCS spreading, or by ridge suction of plume flow during opening of the SCS. If the latter is the case, the volcanic rocks within the SCS basin may not be typical mid-ocean ridge basalts (MORB). It remains puzzling, however, that the transition between the South China continental margin and the SCS basin does not have features typical of a volcanic rifted margin. Clearly, the relationship between mantle plume and SCS opening needs further evaluation. A better understanding of the link between deep processes and opening of the SCS not only requires enhanced studies on igneous petrogenesis, but also is heavily dependent on systematic sampling of seafloor rocks.

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Section: Hainan Mantle Plume and Its Link With The Opening Of The Soumentioning

confidence: 87%

Section: The Opening Of the South China Seamentioning

confidence: 87%

Section: Previous Studies On Volcanic Rocks In the South China Sea Anmentioning

confidence: 99%

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confidence: 99%

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Opening and evolution of the South China Sea constrained by studies on volcanic rocks: Preliminary results and a research design

et al. 2011

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“…Zheng and Zhang, 1996) in Central Jiangxi, Southeast China. and possibly as early as Late Archean; Wang and O'Reilly, 2003) may have survived lithospheric thinning during the Late Mesozoic (Wang and O'Reilly, 2003). This is also suggested by seismic and geothermal data (Hu et al, 2000;Yang, 2003;Yu et al, 2003a), which show that old lithospheric remnants are present in the uppermost layers of the lithosphere (Xu et al, 2002). Nevertheless, the timing and mechanisms for this event remain poorly understood, owing to the lack of knowledge about the nature of the mantle source during the Paleocene that links Late Mesozoic to Late Cenozoic magmatism in Southeast China.…”

Section: Introductionmentioning

confidence: 90%

K-Ar dating, geochemical and Sr-Nd-Pb isotopic systematics of Paleocene mafic rocks in Central Jiangxi, SE China: Evidence for lithosphere replacement

Xie

Mao

et al. 2006

Geochem. J.

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Geochemical and isotopic studies were carried out on Paleocene mafic rocks in the Taihe Basin, central Jiangxi, Southeast China, in order better to understand their magma sources and tectonic implications. K-Ar dating results show that these mafic rocks intruded during the Paleocene (50-65 Ma). These Paleocene mafic rocks are porphyritic diabase and have similar geochemical features, such as strong enrichment of large ion lithophile element (LILE, e.g., Rb, Ba, Sr), slight enrichment of light rare earth element (LREE) and high field strength element (HFSE, e.g., Nb, Ta, Ti, P). The mafic rocks are also characterized by high rare earth element (REE) and minor Eu anomalies (δEu = 0.88-1.2) and have uniform initial 87 Sr/ 86 Sr (0.7041-0.7064) and Pb isotopic composition ( 206 Pb/ 204 Pb = 18.338-18.677) as well as a relatively wide range of initial Nd isotopic ratios (ε Nd (T)) varying from +0.8 to +6.2. These geochemical characteristics are different from those of subduction-related basalts, but similar to oceanic island basalts (OIB). Geochemical and isotopic evidence suggests that mafic rocks in the Taihe Basin were not significantly affected by crustal contamination and originated from asthenospheric mantle with a minor involvement of EM 2 mantle component. It is noted that Cretaceous basaltic rocks in Southeast China show enriched geochemical and isotopic compositions and were derived from a highly heterogeneous lithospheric mantle with minor asthenosphere components. On the other hand, Late Cenozoic basalts in Southeast China, which display OIB-like geochemical characteristics, were probably generated by melting of depleted asthenospheric mantle (DMM or MORB) with an involvement of EM 2 lithospheric mantle and a paucity of EM 1 lithospheric mantle. The Paleocene mafic rocks of the Taihe Basin exhibit transitional geochemical features between Cretaceous and Late Cenozoic basaltic magmatism, indicating that the involvement of asthenospheric mantle beneath Southeast China increased with time from Late Mesozoic to Cenozoic. It is suggested that the lithosphere replacement beneath Southeast China was associated with lithosphere extension and thinning, with decompression melting of the upwelling asthenosphere having taken place during the Paleocene period. Lithosphere replacement might be related to subduction roll-back or/and steepening of Paleo-Pacific plate due to injection of asthenospheric material into the mantle wedge beneath Southeast China.

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Regional heterogeneity in the water content of the Cenozoic lithospheric mantle of Eastern China

et al. 2016

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The major and trace elements and H2O contents of minerals in peridotite xenoliths hosted by the Cenozoic basalts in Northeast China (NEC) were evaluated using electron microprobe, laser‐ablation inductively coupled plasma–mass spectrometry and Fourier transform infrared spectroscopy, respectively. Although a potential loss of H during the xenoliths' ascent cannot be excluded for olivine, orthopyroxene (opx) and clinopyroxene (cpx) largely preserved the H2O contents of their mantle source in all of the samples, as inferred from (1) the homogenous H2O contents within single pyroxene grains and (2) the equilibrium H2O partitioning between cpx and opx. No OH was detected for pyroxenes of peridotite xenoliths from the north part of NEC (NNEC). Combined with previously published data from the North China Craton (NCC) and the South China Block (SCB), the regional heterogeneity in the water contents in the Cenozoic lithospheric mantle beneath the whole Eastern China has been revealed. The lithospheric mantle beneath the NNEC is completely dry. The “bulk” water contents of the lithospheric mantle of the south part of NEC and the NCC have similar ranges and average values, whereas those of the SCB are much higher (12–195 ppm, average 90 ± 45 ppm for whole rock). The regional variations in the H2O content of the Cenozoic lithospheric mantle of Eastern China cannot be caused by partial melting, mantle metasomatism, or variations in redox state. We propose that the lithospheric mantle beneath the different regions of Eastern China may have distinct origins and may have undergone distinct geodynamic processes.

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Xenolith evidence for polybaric melting and stratification of the upper mantle beneath South China

Cited by 68 publications

References 60 publications

Opening and evolution of the South China Sea constrained by studies on volcanic rocks: Preliminary results and a research design

Opening and evolution of the South China Sea constrained by studies on volcanic rocks: Preliminary results and a research design

K-Ar dating, geochemical and Sr-Nd-Pb isotopic systematics of Paleocene mafic rocks in Central Jiangxi, SE China: Evidence for lithosphere replacement

Regional heterogeneity in the water content of the Cenozoic lithospheric mantle of Eastern China

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