Thick, high-velocity crust in the Emeishan large igneous province, southwestern China: Evidence for crustal growth by magmatic underplating or intraplating

2007 ◽  
pp. 841-858 ◽  
Author(s):  
Yi-Gang Xu ◽  
Bin He
Keyword(s):  
High Velocity ◽  
Large Igneous Province ◽  
Southwestern China ◽  
Crustal Growth ◽  
Emeishan Large Igneous Province ◽  
Magmatic Underplating ◽  
Igneous Province

Formation of the North–South Seismic Zone and Emeishan Large Igneous Province in Central China: Insights from P-Wave Teleseismic Tomography

2020 ◽  
Vol 110 (6) ◽  
pp. 3064-3076
Author(s):  
Chuansong He ◽  
M. Santosh
Keyword(s):  
High Velocity ◽  
Large Scale ◽  
P Wave ◽  
Large Igneous Province ◽  
Seismic Zone ◽  
Teleseismic Tomography ◽  
Emeishan Large Igneous Province ◽  
The North ◽  
Igneous Province ◽  
Stress Accumulation

ABSTRACT The geodynamic features of the north–south seismic zone (NSSZ) and the formation of the Emeishan large igneous province (ELIP) in China remain controversial. In this study, we conducted detailed P-wave teleseismic tomography studies in the NSSZ and adjacent regions. The results revealed large high-velocity anomalies beneath the Songpan–Ganzi Block and the South China Block, possibly representing large-scale lithospheric delamination. We further identified low-velocity structures at 50–200 km depths in the western and southern parts of the NSSZ, suggesting an upwelling asthenosphere induced by delamination and the absence of a rigid lithosphere. Two high-velocity structures beneath the Sichuan basin and the Alashan block were also revealed, which may represent the lithospheric roots of these structures. These rigid lithospheric roots may have obstructed the eastward extrusion of the Tibetan plateau and led to stress accumulation and release (triggering earthquakes) in the Longmenshan Orogenic Belt and the northern part of the NSSZ. Because of this obstruction, the eastward extrusion was redirected southeastward to Yunnan in the southern part of the NSSZ, which led to stress accumulation and release causing earthquakes along the Honghe and Xiaojiang faults. The results from this study reveal a high-velocity structure with a subducted slab-like appearance that may represent vestiges of the Paleo-Tethys oceanic lithosphere, which subducted beneath the ELIP and initiating large-scale mantle return flow or mantle upwelling, contributing to the formation of the ELIP.

Primitive magmas in the Emeishan Large Igneous Province, southwestern China and northern Vietnam

Lithos ◽  
2010 ◽  
Vol 119 (1-2) ◽  
pp. 75-90 ◽  
Author(s):  
Eero Hanski ◽  
Vadim S. Kamenetsky ◽  
Zhen-Yu Luo ◽  
Yi-Gang Xu ◽  
Dmitry V. Kuzmin
Keyword(s):  
Large Igneous Province ◽  
Southwestern China ◽  
Emeishan Large Igneous Province ◽  
Northern Vietnam ◽  
Igneous Province

Magmatic underplating beneath the Emeishan large igneous province (South China) revealed by the COMGRA-ELIP experiment

2016 ◽  
Vol 672-673 ◽  
pp. 16-23 ◽  
Author(s):  
Yangfan Deng ◽  
Yun Chen ◽  
Peng Wang ◽  
Khalid S. Essa ◽  
Tao Xu ◽  
...  
Keyword(s):  
South China ◽  
Large Igneous Province ◽  
Emeishan Large Igneous Province ◽  
Magmatic Underplating ◽  
Igneous Province

scholarly journals The formation of North-South Seismic Zone and Emeishan large igneous province in Western China: Insight from teleseismic tomography

2019 ◽  
Author(s):  
Chuansong He
Keyword(s):  
High Velocity ◽  
Large Scale ◽  
Western China ◽  
Large Igneous Province ◽  
The Tibetan Plateau ◽  
Seismic Zone ◽  
Study Region ◽  
Teleseismic Tomography ◽  
Emeishan Large Igneous Province ◽  
Igneous Province

Abstract. Several models have been suggested to explain the earthquake mechanism of the North-South Seismic Zone (NSSZ) and the formation of the Emeishan Large Igneous Province (ELIP). In this study, I extended the study region and carried out detailed teleseismic tomography in the NSSZ and near-by regions. Results identified by this study reveal large plate-like high-velocity anomalies beneath the Songpan-Ganzi Block and the South China Block, which may be associated with large-scale lithospheric delamination, and low-velocity structures at 50–200 km depths in the western and southern parts of this study region, which imply upwelling asthenosphere induced by delamination and the absence of the rigid lithosphere there. Two high-velocity structures beneath the Sichuan Basin and the Alashan Block are revealed, which might be the lithospheric roots of these structures. These rigid lithospheric roots obstructed the eastward extrusion of the Tibetan Plateau and led to stress accumulations and releases (earthquakes) in the Longmenshan Orogenic Belt and the northern part of the NSSZ. Due to obstruction by the Sichuan Basin’s lithosphere, eastward extrusion was redirected southeastward to Yunnan in the southern part of the NSSZ, which led to stress accumulations and releases (earthquakes) along the Honghe and Xiaojiang Faults. This study provide velocity images reveal a slab-like high-velocity structure, which might be associated with the lithospheric vestige of the Paleo-Tethys Ocean that subducted beneath the ELIP, which resulted in large-scale return mantle flow or mantle upwelling and contribute to the LIP formation in early Mesozoic.

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