Binary mixing of lithospheric mantle and asthenosphere beneath Tengchong volcano, SE Tibet: evidence from noble gas isotopic signatures

Chen, Kefei; He, Huaiyu; Stuart, Finlay M.; Liu, Shaolin; Xu, Xiaoyue; Cheng, Zhongjun; Yang, Dinghui; Li, Jiyong; Su, Fei; Wang, Wenshuai

doi:10.1080/00206814.2022.2042744

Cited by 3 publications

(7 citation statements)

References 74 publications

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“…First, the Fo values of olivine in the central area range from 80 to 84, which are relatively close to the values of primitive olivine (88-92; Foley et al, 2013). Second, previous studies have found that 3 He/ 4 He ratios in olivines from the central area are in the range of MORB, indicating that magmas were generated from asthenospheric melts (Chen et al, 2022). Third, melt inclusions from the central area show lower Th/Yb and higher Nb/U ratios than other melt inclusions from the western and central areas (Supplementary Figure S4), indicating that magmas were generated from a primary mantle source.…”

Section: Crustal Contamination and Fractional Crystallizationsupporting

confidence: 63%

“…Third, the Sr-He isotopes can partially provide information on lithospheric thickness. Previous studies suggest that the metasomatized SCLM is characterized by high 87 Sr/ 86 Sr and low 3 He/ 4 He ratios, and that enriched asthenospheric mantle features relatively low 87 Sr/ 86 Sr and high 3 He/ 4 He ratios in the Tengchong volcanic field (Chen et al, 2022). In Figures 9A,B, basalts from the western and eastern areas show lower 3 He/ 4 He and higher 87 Sr/ 86 Sr ratios than those from the central area.…”

Section: Frontiers In Earth Sciencementioning

confidence: 78%

“…Several studies have revealed that the lithospheric mantle and its interaction with the asthenosphere affect the origin of lavas in the Tengchong volcanic field (Zhao and Fan, 2010;Chen et al, 2022). To investigate the contributions of lithospheric mantle and asthenosphere to the magma, we conduct a two-component mixing model in terms of Sr-Nd isotopes.…”

Section: Asthenosphere-lithosphere Interaction and Source Lithologymentioning

confidence: 99%

“…To investigate the contributions of lithospheric mantle and asthenosphere to the magma, we conduct a two-component mixing model in terms of Sr-Nd isotopes. Two endmembers, metasomatized subcontinental lithospheric mantle (SCLM) and enriched asthenospheric mantle, are proposed to form the primary components of the Tengchong volcanic rocks (Chen et al, 2022). According to the mixing model shown in Figure 6, most of the Tengchong basalts plot around the mixing lines and reflect less than 15% of the SCLM contribution (Figure 6).…”

Section: Asthenosphere-lithosphere Interaction and Source Lithologymentioning

confidence: 99%

“…First, the Tengchong basalts span the entire period of major extension (Wang et al, 2007;Wang et al, 2008). Second, the lithospheric mantle is geochemically distinct from the underlying asthenospheric mantle (Chen et al, 2022). To clarify the effect of continental extension on Tengchong volcanism, we collected basalts from the eastern, central and western areas of the Tengchong volcanic field and analyzed the major and trace elements and Sr-Nd isotopes of basalt, as well as the major and trace elements of olivine.…”

Section: Introductionmentioning

confidence: 99%

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Lithospheric thinning beneath the Tengchong volcanic field, Southern China: Insight from Cenozoic calc-alkaline basalts

Chen

Liu²,

Yang³

et al. 2023

Front. Earth Sci.

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The Tengchong Cenozoic volcanic field lies in SE margin of the Tibetan Plateau. The basalts of the Tengchong field exhibit evident spatial-temporal variations, but consensus on their meaning has not been reached yet. In this study, we collected basalts from western, central and eastern areas in the Tengchong volcanic field and measured the whole-rock and olivine major and trace elements of basalts. Tengchong basalts exhibit remarkable chemical and isotopic diversity, showing a strong correlation with eruption locations and ages. Specifically, basalts in the western and eastern areas (formed at 7.2–2.8 Ma) are characterized by high 87Sr/86Sr and low 3He/4He ratios, while those in the central area (formed at 0.6–0.02 Ma) feature low 87Sr/86Sr and high 3He/4He ratios. Based on the temperature- and pressure-dependent elemental partition coefficients, this phenomenon is interpreted as mainly caused by the difference in lithospheric thickness among these areas. On the one hand, the estimated primary magmas in the eastern and western areas show higher SiO2, Na2O, (La/Sm)N, Hf/Lu and Ba/Zr ratios than those in the central area. On the other hand, the Ni contents in olivine phenocrysts are higher in the western and eastern areas than in the central area. As different amounts of extension result in different degrees of decompression of the asthenosphere, finally influencing the compositional variation of magmas, these results indicate that the lithosphere in the eastern and western areas is thicker than that in the central area. In addition, basalts erupted in the eastern and western areas are older than those in the central area, suggesting lithospheric thinning. We propose that lithospheric extension due to slab rollback may have caused lithospheric thinning. In addition, according to the different deformation modes of the crust and lithospheric mantle, our study supports mantle-crust decoupling south of ∼26°N in SE margin of the Tibetan Plateau.

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Section: Crustal Contamination and Fractional Crystallizationsupporting

confidence: 63%

Section: Frontiers In Earth Sciencementioning

confidence: 78%

Section: Asthenosphere-lithosphere Interaction and Source Lithologymentioning

confidence: 99%

Section: Asthenosphere-lithosphere Interaction and Source Lithologymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Lithospheric thinning beneath the Tengchong volcanic field, Southern China: Insight from Cenozoic calc-alkaline basalts

Chen

Liu²,

Yang³

et al. 2023

Front. Earth Sci.

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Deep Low‐Frequency Earthquake Reveals Unsteady Fluid Flow Beneath Tengchong Volcano Field in Southeast Tibet

Niu,

Wang,

Chen

et al. 2024

Geophysical Research Letters

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Deep low‐frequency earthquakes (DLFE) are observed beneath volcanoes worldwide but are limited to island arc volcanoes, hotspot volcanoes, and rift zones. Here we show DLFEs in the Tengchong Volcano Field, southeast Tibet, located ∼300 km from the Indo‐Burma volcanic arc, by analyzing a 12‐year continuous seismic data set. The earthquakes were at a depth of ∼12 km, near the sidewall of the magma body detected by the magnetotelluric survey. The features of isotropic focal mechanism, episodic occurrence, and possible non‐power‐law scaling, with no detectable geodetic deformation, as well as the petrological signatures of the Holocene eruption product, suggest that the earthquakes were likely associated with the weak intermittent magma flows near the magma body. This finding may demonstrate the existence of unsteady magmatic processes in the margin of the Indo‐Eurasia collision zone, which could indicate unneglectable volcanic hazards, underestimated geothermal resources, and mineralization processes in similar regions.

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A multiscale magma system beneath the Tengchong volcano in western Yunnan revealed by ambient noise tomography

Lin,

Liu,

Yang

et al. 2024

Geophysical Journal International

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Summary The western Yunnan is located in the SE Tibetan Plateau, and is characterized by the active Tengchong volcano (TCV), complex crust-mantle coupling and intense earthquakes. To elucidate tectonism in the western Yunnan, we construct a 3D S-wave velocity model to 80 km depth via ambient noise tomography using dense seismic stations. Our model shows significant low-velocity anomalies at different depths in the crust and uppermost mantle. Compared with the results of previous regional tomography, we image low-velocity anomalies consistent with a large-scale source of partial melts in the uppermost mantle beneath the Tengchong and Baoshan blocks, rather than just below the Tengchong block. Our results also reveal a magma chamber extending from the shallow subsurface to the lower crust beneath the TCV, which is fed by the mantle source. Based on these findings, we propose that the mantle source and crustal magma chamber form a multi-scale magma system. Moreover, the mantle source is potentially resulted from asthenospheric upwelling, which is related to the subduction of the Indian slab. In addition, our model shows that the 1976 M7.4 and M7.3 Longling earthquakes occurred near a magma chamber. Thus, fluids from the magma chamber likely reduced the frictional coefficient on the seismogenic fault and caused the Longling earthquakes.

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Binary mixing of lithospheric mantle and asthenosphere beneath Tengchong volcano, SE Tibet: evidence from noble gas isotopic signatures

Cited by 3 publications

References 74 publications

Lithospheric thinning beneath the Tengchong volcanic field, Southern China: Insight from Cenozoic calc-alkaline basalts

Lithospheric thinning beneath the Tengchong volcanic field, Southern China: Insight from Cenozoic calc-alkaline basalts

Deep Low‐Frequency Earthquake Reveals Unsteady Fluid Flow Beneath Tengchong Volcano Field in Southeast Tibet

A multiscale magma system beneath the Tengchong volcano in western Yunnan revealed by ambient noise tomography

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