Terminal Suturing Between the Tarim Craton and the Yili‐Central Tianshan Arc: Insights From Mélange‐Ocean Plate Stratigraphy, Detrital Zircon Ages, and Provenance of the South Tianshan Accretionary Complex

Abstract

The South Tianshan, which extends for 2,500 km from Uzbekistan in the west to northwestern China in the east, is a continuous tectonic unit situated on the southwestern margin of the Altaids or Central Asian Orogenic Belt (CAOB) (Figure 1a) (

Early Permian Syn-Subduction Extension in the South Tianshan (NW China): Insights From A-Type Granitoids in the Southern Altaids

“…The Yili-Central Tianshan arc, separated from the South Tianshan by the Atbashi-Inylchek-South Nalati Fault (Figure 1B), is a Paleozoic magmatic arc located along the Southern Yili block, the Central Tianshan (in China) and the Middle Tianshan (in Kyrgyzstan) (Figure 1B) (Abuduxun et al, 2021a;Han et al, 2011;Xiao et al, 2013); these units record significant accretion-collision events related to closure of the South Tianshan ocean (Alekseev et al, 2009;Gao et al, 2009). This Paleozoic arc, which is mainly underlain by Mesoproterozoic (∼1.4 Ga) to Neoproterozoic (969-708 Ma) basement rocks (e.g., He et al, 2015;Huang et al, 2017), is mostly composed of arc-related calk-alkaline plutonic and volcanic rocks with ages of 490-308 Ma (e.g., Alekseev et al, 2009;Gao et al, 2009;Su et al, 2021;Wang et al, 2020).…”

“…The South Tianshan accretionary complex, formed as a result of continuous northward subduction of the South Tianshan oceanic plate (Abuduxun et al, 2021a;Sang et al, 2018;Xiao et al, 2013), followed by final amalgamation of the Tarim Craton with the Yili-Central Tianshan arc (Alexeiev et al, 2015;Han et al, 2011) (Figure 1B). Accordingly, it records the process of terminal suturing, in the southern Altaids, between the Yili-Central Tianshan arc and the northern passive margin of the Tarim Craton (Han et al, 2011;Xiao et al, 2013).…”

“…They were previously considered to be passive margin sediments on the northern slope of the Tarim Craton (Han et al, 2011;Biske et al, 2018). Recently, however, fragmented and/or dismembered elements of ocean plate stratigraphy (OPS) were recognized in previously assigned Silurian to Carboniferous strata from several locations in the South Tianshan (Safonova et al, 2016;Sang et al, 2018;Abuduxun et al, 2021aAbuduxun et al, , 2021b. They are composed of closely associated MORB/OIB-type basalts, ribbon cherts and turbidites that occur in mélanges with a typical block-in-matrix structure or in coherent strata in thrust-repeated tectonic slices (Sang et al, 2018;Abuduxun et al, 2021b).…”

“…It grew southwards from the Siberian Craton by the successive accretion of multiple arcs, accretionary complexes and micro-continents (e.g., Windley et al, 2007;Xiao et al, 2009;Safonova et al, 2017;Yakubchuk, 2017;Li et al, 2018), followed by its final amalgamation with the Tarim and North China Cratons along the South Tianshan and Solonker sutures (Xiao et al, 2003(Xiao et al, , 2014. Accordingly, the South Tianshan was subjected to the latest collisional event in the southern Altaids (Xiao et al, 2013;Han et al, 2016;Abuduxun et al, 2021a), and consequently provides critical constraints on the termination of accretion.…”

“…A result of the Permian Tarim mantle plume (e.g., Zhang and Zou, 2013). Although it is well accepted that the South Tianshan was still under a subduction regime in the Permian (Li et al, 2005;Xiao et al, 2013;Sang et al, 2018;Wen et al, 2020;Abuduxun et al, 2021a), less attention has been paid to the petrogenesis of the Permian granitoids in relevant tectonic models. Thus, these conflicting views have created an important, but unresolved question, which is critical for understanding the Permian accretionary architecture of the southern Altaids.…”