Postdoctor AO Songjian and his teacher XIAO Wenjiao present the results of a detailed structural, geochemical and geochronological study of the Yueyanshan-Xichangjing ophiolite, one of the best exposed and preserved Beishan ophiolites.

They put the tectonic setting of this dated ophiolite and associated accretionary complex into a regional tectonic framework in order to demonstrate the accretionary tectonics between a micro-continental block and an island arc.

Together with data from the literature, their work demonstrates that multiple overlapping periods of accretion existed in the Palaeozoic in the northern and southern Altaids. Therefore, a model of multiple accretion by closure of several ocean basins is most viable.

Fig.1. Geological map and the Jiuquan–Ejinaqi road cross-section of the Yueyashan–Xichangjing ophiolite. (Image by AO)

Ao et al. Cambrian to Early Silurian accretionary process in the Beishan Collage, NW China: implications for architecture of the Altaids. Geological Magazine. 2012, 149: 606-625 (Download Here)