Hydrous Melting Driven Upwelling From the Mantle Transition Zone in the Mongolia Plateau Revealed by Receiver Function Analysis

Abstract

Mongolia Plateau, located at the center of Central Asian Orogenic Belt (CAOB) and close to the frontier of the subducting Pacific slab, is widely distributed with the young active intracontinental volcanism (Figure 1). There is a controversial debate about the mechanism or origin of the widely dispersed, long-term intraplate Cenozoic magmatism. Several upper mantle low-velocity or low-density zones (M.

Upper mantle melt caused by a subducted slab in the Indian-Eurasian continental subduction zone

“…This cannot be explained by the phase transition of serpentine into dense hydrous magnesium silicate 35 , nor can it be explained by the phase transformation of olivine 36 . Similar LVLs are found worldwide [5][6][7][8][9][10][11][12][13][14][15] , and these results are usually explained as being caused by partial melting induced by water and/or other volatiles (i.e. CO 2 ).…”

“…The optimal structural parameters for the LVL are sought in the range of dup_LVL = 300-400 km, dlow_LVL = 390-430 km and dVp_LVL = −0.5 to −6.0%, with intervals of 5 km and 0.5% based on global variations in this structure as obtained in previous studies [5][6][7][8][9][10][11][12][13][14][15] . Similarly, the parameter ranges for the HVA are set to dup_HVA = 440-620 km, dlow_HVA = 650-700 km, and dVp_HVA = 0.5-2.5% 14,15 .…”

“…In oceanic subduction zones, e.g. the present circum-Pacific subduction zone 6,7,10,11 , the ancient Asian oceanic subduction zone 5,12,13 and the Tethyan oceanic subduction zone 14,15 , these LVLs are widely explained as partial melting due to hydrous and/or other volatile materials upwelling from the MTZ triggered by slab subduction on a regional or global scale 5,7,[10][11][12][13][14][15] . Although numerical modelling shows that this process can be expected on a regional 4 or global 1 scale, direct observational evidence to construct the relationship between such an LVL and a subducted slab is still absent.…”

Cenozoic Uplift and Volcanism of Hangai Dome, Central Mongolia Triggered by Lower Mantle Upwellings

“…However, such negative phases are absent in our stacked RFs (Figure 3) and RF waveforms of different frequencies (Figure S8 in Supporting Information ), indicating that the negative signals just prior to the converted phases from d410 observed by He et al. (2022) may be sidelobes caused by data processing.…”

“…On the other hand, He et al. (2022) ascribed the uplift of Hangai Dome and the intraplate volcanism to the hydrous upwelling from the MTZ based on the observation of negative phases atop d410. However, such negative phases are absent in our stacked RFs (Figure 3) and RF waveforms of different frequencies (Figure S8 in Supporting Information ), indicating that the negative signals just prior to the converted phases from d410 observed by He et al.…”