Assembly, Accretion and Breakup of the Paleo-Mesoproterozoic Columbia Supercontinent: Records in the North China Craton

Abstract

Established pre-Rodinian connections between cratonic blocks around the world lead to the proposal of a Paleo-Mesoproterozoic supercontinent, named Columbia, which may have contained nearly all of the earth's continental blocks at some time between 1.8 Ga and 1.5 Ga. The assembly of Columbia was completed during the global-scale 2.1-1.8 Ga collisional event, forming the 2.1-2.0 Ga Transamazonian Orogen in South America, 2.1-2.0 Ga Eburnean Orogen in West Africa, ∼2.0 Ga Limpopo Belt in Southern Africa, 1.9-1.8 Ga Trans-Hudsonian and Nagssugtoqidain Orogens in Laurentia, 1.9-1.8 Ga Kola-Karelia Orogen in Baltica, 1.9-1.8 Ga Akitkan Orogen in Siberia, ∼1.8 Ga Central Indian Tectonic Zone in India, and ∼1.85 Ga Trans-North China Orogen in North China. The outward accretion of Columbia is evidenced by the presence of 1.8-1.3 Ga magmatic zones bordering the present southern margins of North America, Greenland, Baltica, North China and North Australia, which consist of juvenile volcanogenic sequences and granitoid suites resembling those of present-day island arcs and active continental margins, representing subduction-related episodic outbuilding on the continental margins of Columbia. The breakup of Columbia commenced at ∼1.6 Ga and continued until ∼1.2 Ga, as indicated by widespread 1.6-1.2 Ga continental rifting, anorogenic magmatism and emplacement of mafic dyke swarms in all cratonic blocks of Columbia. Like most other cratonic blocks, the North China Craton records the history of the assembly, accretion and breakup of Columbia. New data indicate that the evolution of the North China Craton involved discrete Eastern and Western Blocks that developed independently during the Archean and collided to form a coherent craton during a global Paleoproterozoic orogenic event. Following the final amalgamation at ∼1.85 Ga, the North China Craton underwent a long-lived (1.8-1.4 Ga), subduction-related, outgrowth along its southern margin, forming the Xiong'er volcanic belt. The most robust evidence in the North China Craton for the Mesoproterozoic fragmentation of Columbia comes from the 1.6-1.2 Ga Zhaertai-Bayan Obo-Huade-Weichange rift zone along the northern margin of the craton. The development of this rift zone may have been associated with the separation of the North China Craton from India, whose western margin is considered to have connected to the northern margin of the North China Craton until the start of the Mesoproterozoic when the dispersion of Columbia commenced.