Research Paper GEOSPHERE From Ordovician nascent to early Permian mature arc in the southern Altaids: Insights from the Kalatage inlier in the Eastern GEOSPHERE, v. 17, no. 2 Tianshan, NW China https://doi.org/10.1130/GES02232.1 Qigui Mao1,2, Jingbin Wang2, Wenjiao Xiao1,3,4, Brian F. Windley5, Karel Schulmann6, Songjian Ao1, Mingjing Yu2, Ji’en Zhang1, and Tonghui Fang2 1Xinjiang Research Center for Mineral Resources, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China 18 figures; 4 tables; 1 supplemental file 2Beijing Institute of Geology for Mineral Resources, Beijing 100012, China 3State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China 4 CORRESPONDENCE: [email protected] College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China 5Department of Geology, The University of Leicester, Leicester LE1 7RH, UK 6Institut de Physique du Globe de Strasbourg, UMR7516, University of Strasbourg/EOST, CNRS, 1 rue Blessig, F-67084 Strasbourg, France CITATION: Mao, Q.G., Wang, J.B., Xiao, W.J., Windley, B.F., Schulmann, K., Ao, S.J., Yu, M.J., Zhang, J.E., and Fang, T.H., 2021, From Ordovician nascent to ABSTRACT ■ INTRODUCTION early Permian mature arc in the southern Altaids: In- sights from the Kalatage inlier in the Eastern Tianshan, NW China: Geosphere, v. 17, no. 2, p. 647–683, https:// The Kalatage inlier in the Dananhu-Haerlik arc is one of the most import- The southern Altaids, or Central Asian orogenic belt, is one of the most doi.org /10.1130 /GES02232.1. ant arcs in the Eastern Tianshan, southern Altaids (or Central Asian orogenic important sites of Neoproterozoic–Phanerozoic juvenile crustal growth in the belt). Based on outcrop maps and core logs, we report 16 new U-Pb dates in world (Fig. 1A; Şengör et al., 1993; Şengör and Natal’in, 1996; Windley et al., Science Editor: Shanaka de Silva order to reconstruct the stratigraphic framework of the Dananhu- Haerlik arc. 2007; Wilhem et al., 2012; Xiao et al., 2015). The Altaids formed by the suc- Associate Editor: Alan Whittington The new U-Pb ages reveal that the volcanic and intrusive rocks formed in the cessive accretion of oceanic and continental arcs and accretionary complexes interval from the Ordovician to early Permian (445–299 Ma), with the oldest (Coleman, 1989; Dobretsov et al., 1995; Gao et al., 1998; Buchan et al., 2002; Received 31 December 2019 diorite dike at 445 ± 3 Ma and the youngest rhyolite at 299 ± 2 Ma. These Bazhenov et al., 2003; Xiao et al., 2003, 2004, 2008, 2010; Li, 2004; Li et al., Revision received 3 June 2020 Accepted 12 November 2020 results constrain the ages of the oldest basaltic and volcaniclastic rocks of the 2006a; Ma et al., 1997; Shi et al., 2010; Wainwright et al., 2011a, 2011b). This Ordovician Huangchaopo Group, which were intruded by granite- granodiorite- accretion involved major vertical crustal growth through arc magmatism in Published online 5 February 2021 diorite plutons in the Late Ordovician to middle Silurian (445–426 Ma). The convergent and/or extensional settings during the late Paleozoic and early second oldest components are intermediate volcanic and volcaniclastic rocks Mesozoic (Han et al., 1997, 1998, 2004; Chen et al., 2000, 2006; Jahn et al., of the early Silurian Hongliuxia Formation (S1h), which lies unconformably 2000; Wu et al., 2000, 2002; Jahn, 2004; Yuan et al., 2007; Mao et al., 2014b). on the Huangchaopo Group and is unconformably overlain by Early Devonian The Eastern Tianshan (Fig. 1), which is situated in the South Tianshan– volcanic rocks (416 Ma). From the mid- to late Silurian (S2-3), all the rocks were Solonker suture zone of the southern Altaids (Xiao et al., 2004, 2010; Mao et exhumed, eroded, and overlain by polymictic pyroclastic deposits. Following al., 2014b, 2018), involved episodic amalgamation and accretion of continental subaerial to shallow subaqueous burial at 416–300 Ma by intermediate to felsic margin arcs, island arcs, ophiolites, and accretionary wedges (Ma et al., 1997; volcanic and volcaniclastics rocks, the succession was intruded by diorites, Li, 2004; Xiao et al., 2004; Wang et al., 2006; Windley et al., 2007). Consequently, granodiorites, and granites (390–314 Ma). The arc volcanic and intrusive rocks diverse models have been applied to better understand the geological evolu- are characterized by potassium enrichment, when they evolved from mafic tion of the Chinese Eastern Tianshan in the Paleozoic, and many controversies to felsic and from tholeiitic via transitional and calc-alkaline to final high-K remain, especially regarding the stratigraphic framework, relationships among 87 86 calc-alkaline compositions with relatively low initial Sr values, ( Sr/ Sr)i = formations, the concept and nature of the Dananhu-Haerlik arc (Xiao et al., 0.70391–0.70567, and positive εNd(t) values, +4.1 to +9.2. These new data sug- 1992; Ma et al., 1997; Xiao et al., 2004; Wang et al., 2006; Muhetaer et al., 2010; gest that the Dananhu-Haerlik arc is a long-lived arc that consequently requires Li et al., 2016; Zhang et al., 2016), and the detailed geological evolution of the a new evolutionary model. It began as a nascent (immature) intra-oceanic arc associated tectonic belts (Xiao et al., 1992; Ma et al., 1997; Feng et al., 2002; in the Ordovician to early Silurian, and it evolved into a mature island arc in Li, 2004; Xiao et al., 2004; Wang et al., 2006; Wang et al., 2014; Li et al., 2016). the middle Silurian to early Permian. The results suggest that the construction In order to better understand the tectonic evolution of the Eastern Tianshan, of a juvenile-to-mature arc, in combination with its lateral attachment to an we need a detailed temporal- tectonostratigraphic framework for the highly incoming arc or continent, was an important crustal growth mechanism in thrusted sequences. In this paper, we focus on one portion of the Dananhu- the southern Altaids. Haerlik arc: the Kalatage geological inlier, which is mainly composed of weakly This paper is published under the terms of the metamorphosed Ordovician to Permian volcanic, volcaniclastic, and granitic CC-BY-NC license. Wenjiao Xiao (肖文交) https://orcid.org/0000-0003-3518-0526 rocks, and minor marbles together with several types of mineral deposits © 2021 The Authors GEOSPHERE | Volume 17 | Number 2 Mao et al. | Ordovician to early Permian mature arc in Eastern Tianshan Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/17/2/647/5259561/647.pdf 647 by guest on 24 September 2021 Research Paper 60E 65E 70E 75E 80E 85E 90E 95E 100E 105E 110E 115E 45N Siberian A Craton Aral Sea Lake Baikal Kazakhstan Orocline hash La alk ke B Altai 40N Kizil Kum desert Tuva-Mongol Junggar Orocline Craton Baykalides Fig. 1B Pre-Altaid continental crust in the Altaids South Tianshan Vendian to Early Cambrian Solonker Subduction-accretion Middle Cambrian to Silurian complexes Devonian to Carboniferous-Permian Beishan Cambrian to Ordovician (Kazakhstan) and Early- Middle/Cambrian (Altay) oceanic magmatic arc Tarim Craton Basins with unknown basement Pre-Vendian suture North China Craton Carboniferous-Permian suture Permian to Mid-Triassic suture 0 km 500 VMS deposit Porphyry deposit 87° 90° 96°E Precambrian 88°30′Ordovician-Silurian Devonian Carboniferous 93°E 4 B Permian Jurassic Cenozoic Mafic-ultramafic complex Wulumuqi Bogda intra-arc basin Ophiolite Granite Fault 1 Kawabulake-Xingxingxia Fault 2 Aqikekuduke-Shaquanzi Fault 3 Kangguer Fault 4 Kalameili Fault Haerlik Mountain 43°N Turpan Basin 43°N Fig. 2 Hami Central Tianshan Arc Xiaoshitouquan Tulaergen Dacaotan Dananhu Dananhu-Haerlik Arc Sanchakou Xiaorequanzi Kezier Huangshan 3 Tuwu 42°N Kangguer Kangguer Forearc 42°N South Tianshan Yamansu Arc Yamansu 2 Xingxingxia Central Tianshan Arc 1 1 Beishan Tarim Craton 0 km 40 90°E 93°E 87°E 96°E Figure 1. (A) Schematic tectonic map of Central Asia (Şengör et al., 1993; Xiao et al., 2015) showing the position of the Eastern Tianshan in part B. (B) Schematic geological map of the Eastern Tianshan (modified after XBGMR, 1993; Xiao et al., 2004) showing the location of the Kalatage inlier within the desert of the Turpan Basin. The Kalatage inlier is a western continuation of the Dananhu-Haerlik arc. Some Paleozoic plutons with their dates of formation host four types of mineral deposits at seven localities. The major faults indicated separate the South Tianshan, Central Tianshan, the Yamansu arc, the Dananhu-Haerlik arc, and Angaran margin. VMS—volcanogenic massive sulfide. GEOSPHERE | Volume 17 | Number 2 Mao et al. | Ordovician to early Permian mature arc in Eastern Tianshan Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/17/2/647/5259561/647.pdf 648 by guest on 24 September 2021 Research Paper (see Figs. 2 and 3; Mao et al., 2019), such as volcanogenic massive sulfide by the Kawabulake-Xingxingxia fault (Fig. 1B). This zone includes Silurian– (VMS)–type Cu-Zn-(Au-Ag) deposits, porphyry-type Cu (Au) deposits, subvol- Carboniferous turbidites, Silurian–late Carboniferous ophiolites, cherts, canic hydrothermal vein–type Cu (Au) deposits, and magmatic Cu-Ni sulfide volcaniclastic rocks, and mélanges, and Devonian–early Carboniferous eclog- deposits. We reconstructed the Paleozoic stratigraphic framework of the vol- ites and blueschists (Gao et al., 1998; Xiao et al., 2004; Du et al., 2019). canic and sedimentary rocks at Kalatage mainly from our outcrop mapping The Central Tianshan block is located between the Kawabulake-Xingxingxia and core logging combined with 16 new U-Pb ages and geochemical data to and Aqikekuduke-Shaquanzi faults (Fig. 1B), and it contains Precambrian better understand the history of magmatic activity in the arc. These results amphibolite-facies migmatitic gneisses, quartz schists, and marbles with U-Pb improve our knowledge of the geological evolution of the Dananhu- Haerlik arc ages ranging from 1900 Ma to 900 Ma (Hu et al., 2000; Xiu et al., 2002; Liu et and place new constraints on the tectonic evolution of the southern Altaids.