Paleoproterozoic Plate Tectonics Recorded in the Northern Margin Orogen, North China Craton

Abstract

Modern plate tectonics on Earth is characterized by a kinematically linked global network of internally-rigid plates that rotate about Euler poles and are recycled via subduction and sea-floor spreading (e.g.,

A paradigm shift: North China Craton's North Margin Orogen is the collisional suture with the Columbia Supercontinent

“…1). Together, the North Margin Orogen of Wu et al (2022a) and the Birimian terranes of West Africa as seen on this reconstruction to form a large 2.3-2.0 Ga accretionary orogen, that collided with the other blocks of Columbia in the Atlantica configuration at 1.85 Ga. The importance of using the correct orogen to fit the NCC into the Columbia Supercontinent reconstruction is more than academic.…”

“…Additionally, the Paleoproterozoic Birimian encompasses volcanic greenstone belts, and granitic intrusions related to the Eburnean orogeny, with ages between 2.2 to 1.8 Ga (Grenholm, 2019), similar to parts of the North Margin Orogen. The deformation period during Eburnean orogenesis is focused at about 2.1 Ga (Para-Avila, 2017), similar to the period when the north margin of the NCC was an active Andean-type accretionary orogen margin (Kusky et al, 2016;Wu et al, 2018Wu et al, , 2022a.…”

“…Professor Chen Wu and his colleagues initially recognized a circa 1.9 Ga mélange along the north margin of the craton (Wu et al, 2018), then continued mapping and through detailed field studies (Wu et al, 2022a, b) have now documented many of the classical features of collisional orogens along the north margin of the craton, at 1.9-1.85 (extending to 1.78 Ga for post collisional magmatism), using long-established indicators of collisional orogens. Specifically, Wu et al (2022a) document the presence of an east-west striking belt of 2.2-2.0 Ga continental margin magmatic arc rocks, an east-west striking 1.9-1.88 Ga tectonic mélange and mylonitic shear zones, and lower Paleoproterozoic strata folded by N-S contraction, all metamorphosed to granulite facies at 1.9-1.8 Ga. Analysis of a huge dataset of detrital zircons by Wu et al (2022a) is consistent with Neoarchean arc/continent collision in the older orogenic belt in the center of the craton, followed by active continental margin arc tectonics along the north margin of the craton from 2.2-1.85 Ga forming the Bayan Obo subduction/accretion mélange, then ridge subduction at 1.92 Ga, followed by collision with Columbia Supercontinent at 1.93-1.80 Ga, then post-collisional magmatism in the range of 1.87-1.80, with the final pulse of post-collisional lamprophyre dikes intruding at 1.78-1.77 Ga.…”

“…Specifically, Wu et al (2022a) document the presence of an east-west striking belt of 2.2-2.0 Ga continental margin magmatic arc rocks, an east-west striking 1.9-1.88 Ga tectonic mélange and mylonitic shear zones, and lower Paleoproterozoic strata folded by N-S contraction, all metamorphosed to granulite facies at 1.9-1.8 Ga. Analysis of a huge dataset of detrital zircons by Wu et al (2022a) is consistent with Neoarchean arc/continent collision in the older orogenic belt in the center of the craton, followed by active continental margin arc tectonics along the north margin of the craton from 2.2-1.85 Ga forming the Bayan Obo subduction/accretion mélange, then ridge subduction at 1.92 Ga, followed by collision with Columbia Supercontinent at 1.93-1.80 Ga, then post-collisional magmatism in the range of 1.87-1.80, with the final pulse of post-collisional lamprophyre dikes intruding at 1.78-1.77 Ga. The North Margin Orogen was then intruded by 1.87-1.78 plutons of the anorthosite -mangerite -charnockite -alkali feldspar granitoid suite (Peng et al, 2014), which are common in post-continental collisional settings such as the Rodinian Belts, including the Adirondacks the Grenville Province.…”

“…While the position of the North China Craton in the Columbia Supercontinent has been debated (Rogers and Santosh, 2002;Zhao et al, 2002;Meert, 2012), this is largely because most workers have been assuming the north-south striking TNCO in the center of the craton marked the collisional suture with Columbia. Since this turns out to not be true, confirmed by the new work reported by Wu et al (2022a), one of the biggest reasons the NCC was so hard to fit into Columbia, was that these attempts were using the wrong orogen as the suture! The reconstruction of Kusky and Santosh (2009) used the North Margin Orogen to fit the NCC into Columbia, correlating this belt with the Trans-Amazonian of South America and Eburnian/Birimian orogens of West Africa.…”