Structural restoration of an Eo-Mesoarchean (3.8–2.9 Ga) terrane, Eastern China, dissected by the Tanlu fault zone

Abstract

Ancient gneissic terranes are critical rare materials that can reveal the Earth's early crustal evolution. This paper presents reconstruction of the oldest Eo-Mesoarchean gneissic terrane (3.8–2.9 Ga) in the eastern North China Craton that was partitioned by the ENE-WSW striking Tanghe-Hanling strike-slip fault (THF). The THF is a splay off the Tanlu fault zone and has been traced for 130 km and is 1–1.5 km wide. The THF has a 28 km sinistral offset, which has been established by detailed field observation. Restoring the 28 km offset, means that: (1) A sizeable potential area is recognized for searching for more 3.8–2.9 Ga Eo-Mesoarchean rocks; (2) A large NW-striking late Archean BIF belt is correlated with another at Anshan. Our data integrate with regional structural information of the Tanlu fault zone; we suggested that the Tanlu fault zone has an eastwards-fan splay pattern geometric feature in its northern part. Accordingly, we further restore the ancient tectonic configuration of eastern Asia before the Tanlu fault zone initiation. Eo-Mesoarchean rocks and 2.7–2.9 Ga terranes cropping out in Eastern Block of the North China Craton are arranged in line with NNW-SSE strike, which is consistent with their oriented gneissic foliations.