Crustal velocity structure of Cathaysia Block from an active-source seismic profile between Wanzai and Hui''an in SE China

Lin J. ; Xu T. ; Cai H. ; Lü Q. ; Bai Z. ; Deng Y. ; Zhang Y. ; Huang M. ; Badal, José (Universidad de Zaragoza) ; Jin X.

Resumen: With the purpose of exploring the widely distributed Mesozoic granitoids in SE China and the related mineralization, we carried out a new 530-km-long seismic wide-angle reflection and refraction (WARR) profile along the transect Wanzai- Hui''an. Based on a previous exploration in 2012 and the analysis of this WARR profile, we have deduced a detailed P-wave velocity model of the crust and uppermost mantle. The main results are: (1) The crustal thickness is about 30 to 32 km beneath the Yangtze Block and West Cathaysia, and 29 to 30 km below the East Cathaysia, which represents a significant thinning with respect to the worldwide average thickness of shields and platforms. (2) The variation in seismic velocity between the upper crust and middle-lower crust in the Yangtze Block and the Cathaysia Blocks indicates that the Shaoxing-Jiangshan-Pingxiang Fault (SJPF) is the tectonic boundary between the Yangtze and Cathaysia and the Zhenghe-Dapu Fault (ZDF) is the tectonic boundary between the west and east Cathaysia. (3) The middle crust exhibits a low P-wave velocity layer of 6.2 km/s below the Wuyishan Metallogenic Belt (WMB). This low velocity layer can be attributed to the delamination during the Caledonian orogeny and the Yanshanian extension. (4) The middle-lower crust shows a clear lateral velocity variation from west to east in Cathaysia. The subduction of the Paleo-Pacific plate is believed to be the main reason for the extensional tectonic environment and magmatism during the Yanshanian (Jurassic-Cretaceous) period, leading to significant crustal and lithospheric thinning. Relatively high velocity in the middle-lower crust and widely disseminated Cretaceous volcanic rocks in East Cathaysia may be related to the slab rollback of the Paleo-Pacific plate in the late Yanshanian (Cretaceous) period.

Idioma: Inglés

DOI: 10.1016/j.tecto.2021.228874

Año: 2021

Publicado en: Tectonophysics 811 (2021), 228874 [12 pp]
ISSN: 0040-1951

Factor impacto JCR: 3.66 (2021)

Categ. JCR: GEOCHEMISTRY & GEOPHYSICS rank: 32 / 87 = 0.368 (2021) - Q2 - T2

Factor impacto CITESCORE: 7.1 - Earth and Planetary Sciences (Q1)

Factor impacto SCIMAGO: 1.545 - Geophysics (Q1) - Earth-Surface Processes (Q1)

Tipo y forma: Artículo (PostPrint)

Área (Departamento): Área Física Teórica (Dpto. Física Teórica)