Crustal Footprint of the Hainan Plume Beneath Southeast China

Abstract

Although global and regional seismic tomography results have revealed the presence of a mantle plume beneath Hainan Island, there is little evidence for a hotspot track associated with the Hainan plume. Here a joint inversion of satellite gravity measurements and seismic surface wave dispersion data was performed, and the results show that a linear corridor of high seismic velocity anomalies beneath the crust is located northeast of Hainan Island beneath the Southeast China. Geodynamic modeling further demonstrates that this corridor could have been formed by the interactions between a mantle plume and the continental lithosphere with a weak lower crust. Volcanic age distributions of sporadic oceanic island basalts suggest that this track was likely formed since the late Cretaceous, which helps to constrain the averaged plate velocity of the South China Block, relative to the Hainan plume, to be ~1.8 cm/year to the northeast since 80 Ma. Our result provides a novel explanation for the crustal thickness variations, related Vs anomalies, and observed oceanic island basalts in this area. It also provides an independent way for constraining plate motion history of the continental lithosphere.

Tarim Large Igneous Province Caused by a Wide and Wet Mantle Plume

“…Therefore, we obtain the dynamic topography corresponding to the three periods during the interactions between the Tarim craton and the Tarim plume (Figures 3j–3l). The dynamic topography rises with time, which is consistent with previous results (Liu et al, 2018; Yang & Leng, 2014). Specifically, the simulated maximum pre‐eruption topographic uplift is ~900 m with a radius of 500 km (Figure 3j), which is consistent with stratigraphic records from the Tarim craton between the late Carboniferous and early Permian (red dashed lines in Figure 1a, Li, Yang et al, 2014).…”

“…On the other hand, lithospheric thinning leads to strong decompression melting; thus, we explore the effects of the main factors controlling lithospheric erosion (Figure 6b). The results suggest that the plate motion velocity, plume radius, and Ra prominently influence lithospheric thinning, which is consistent with previous results (Liu et al, 2018; Yang & Leng, 2014). In addition, to better understand the influence of plate motion on LIP distribution, we perform a statistical analysis of plate motion rates during LIP formation based on plate reconstructions from the GPlates software (Young et al, 2019).…”

Seismic Anisotropy in the Java‐Banda and Philippine Subduction Zones and its Implications for the Mantle Flow System Beneath the Sunda Plate

“…In addition, the flow geometry beneath the South China Sea has barely been investigated, in particular that associated with the Hainan mantle plume (e.g., Liu et al, ; Mériaux et al, ; Yu et al, ), which has not been detected. A future investigation of mantle flow beneath the South China Sea is thus important to understand how the Hainan plume has been influencing the flow systems beneath the Sunda Plate.…”

Fingerprinting subducted oceanic crust and Hainan Plume in the melt sources of Cenozoic Basalts from the South China Sea Region

“…Temporally, the occurrence of combined DMM and EM2 mantle domains beneath SE Eurasia has been prevalent since the Late Mesozoic (Wang, Chung, et al, 2012; Wang, Fan, Cawood, & Li, 2008). This timeframe is clearly earlier than the earliest starting time of the Hainan Plume activity proposed to date (~80 Ma; Liu et al., 2018). Therefore, it is plausible to attribute the EM2‐like signatures of the Cenozoic intraplate volcanic suites in the SCS region to the lithospheric mantle, which was metasomatized and modified by melts/fluids derived from the subducted Pacific slab that has been stagnant in the MTZ since the late Mesozoic.…”

“…On the other hand, a plume‐like low‐velocity structure in the upper and lower mantle (Huang & Zhao, 2006), a thinned MTZ (Wang & Huang, 2012) and regionally high mantle potential temperatures (Wang, Li, et al, 2012) imply the existence of a thermal plume originating from the lower mantle or the CMB (core–mantle boundary). However, the emplacement time of the Hainan Plume is still unresolved, and some of the proposed time windows include late Cretaceous (~80 Ma; Liu, Chen, Leng, Zhang, & Xu, 2018), early Cenozoic (~60 Ma; Zhou et al., 2009), late Oligocene (23.8 Ma; Yu et al., 2018) and late Miocene (Huang et al., 2013).…”