RT Journal Article
SR Electronic
T1 North-dipping relict subduction of the Paleo-Asian Ocean at the southeastern margin of the Mongolian Terrane: Study of two parallel deep seismic profiles
JF American Journal of Science
JO Am J Sci
FD American Journal of Science
SP 380
OP 395
DO 10.2475/02.2022.09
VO 322
IS 2
A1 Fu, Wei
A1 Hou, Hesheng
A1 Gao, Rui
A1 Wang, Haiyan
A1 Guo, Lei
A1 Zhou, Jianbo
A1 Yang, Jin
A1 Guo, Rui
A1 Pan, Zongdong
YR 2022
UL http://www.ajsonline.org/content/322/2/380.abstract
AB The final closure of the Paleo-Asian Ocean (PAO) and its tectonic characteristics have been debated for several decades owing to a lack of high-resolution information on the lithosphere structure. Scholars have been attempting to explain deep tectonic evolutionary processes while studying continental growth at the southern margin of the Mongolian Terrane. In a bid to provide a new interpretation of the deep structure with a higher resolution, we study two reprocessed deep seismic reflection profiles. We studied the northern part (210 km long) of the 630-km-long deep seismic reflection profile extending across the North China Craton (NCC) margin to the northern Sino-Mongolia border in the west; and a parallel profile (80 km long) in the east near the Sino-Mongolia border. Both profiles are characterized by consistently north-dipping layered reflections projecting from the lower crust to the upper mantle, with an estimated thickness of 3.6 to 6 km between adjacent reflections beneath the Uliastai and Hegenshan belts. Arched reflections are observed in the middle and lower crust; these may have been caused by later magmatic activities. In addition, the Moho reflection is observed to be fairly continuous and flat in most parts of these two profiles. The layered lower crust reflections and mantle reflections serve as important evidence that northward subduction occurred during the closure of the Paleo-Asian Ocean at the southeastern margin of the Mongolian Terrane. We propose a detailed model of the evolutionary processes from the early Paleozoic to early Mesozoic. The proposed model explains how these deep reflections were formed.