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Melanges through time: Life cycle of the world's largest Archean melange compared with Mesozoic and Paleozoic subduction-accretion-collision melanges

2020-10-01
Kusky, Timothy
Wang, Junpeng
Wang, Lu
Huang, Bo
Ning, Wenbin
Fu, Dong
Peng, Hongtao
Deng, Hao
Polat, Ali
Zhong, Yating
Shi, Guanzhong
Melanges represent a significant component of collisional and accretionary orogenic belts. We present a comparison of subduction-accretion melanges of different ages to test how melange-forming processes at convergent margins changed through time. We describe the Mesozoic McHugh melange in Alaska, and the Paleozoic Proto-Tethyan Laohushan melange of the Qilian Orogenic Belt of the Alpine-Himalayan chain, together with documentation of a Neoarchean melange that marks the suture between the Eastern Block and Central Orogenic Belt of the North China Craton (NCC). The McHugh is a classic accretionary melange that has not yet experienced a collision, and the Laohushan is an accretionary/collisional melange with structures related to both stages of its evolution. We compare the characteristics of these melanges with the world's largest Archean melange, the newly-documented circa 2.5 Ga 1600 km long Jianping-Zunhua-Zanhuang-Dengfeng (JZZD) melange of the North China Craton.