Closure of the Solonker basin: Paleomagnetism of the Linxi and Xingfuzhilu formations (Inner Mongolia, China)

Abstract

The results of petro- and paleomagnetic studies of the volcanic and sedimentary rocks of the Linxi and Xingfuzhilu formations (Solonker Zone, Inner Mongolia, China) are reported. The direction of an ancient prefold magnetization component is determined (Dec = 157.8°, Inc =–43.5°, K = 10.0, α95 = 5.8°) and the coordinates of the corresponding paleomagnetic pole at ~250 Ma are calculated (Plat = 64.2°, Plong = 350.6°, dp = 4.5°, dm = 7.2°). The obtained and published paleomagnetic, geochronological, and geochemical data permit palinspatic reconstructions, according to which (1) a paleobasin ~500 km wide existed between the Late Permian and beginning of the Early Triassic (250 Ma); and (2) its closure occurred not in the Permian as previously thought, but at the beginning of the Early Triassic.