RESEARCH Ages and geochemistry of Early Jurassic granitoids in the Lesser Xing’an–Zhangguangcai Ranges, NE China: Petrogenesis and tectonic implications Mao-Hui Ge1, Jin-Jiang Zhang2,*, Long Li3, and Kai Liu4 1INSTITUTE OF GEOLOGY, CHINESE ACADEMY OF GEOLOGICAL SCIENCES, BEIJING 100037, CHINA 2KEY LABORATORY OF OROGENIC BELTS AND CRUSTAL EVOLUTION, SCHOOL OF EARTH AND SPACE SCIENCES, PEKING UNIVERSITY, BEIJING 100871, CHINA 3DEPARTMENT OF EARTH AND ATMOSPHERIC SCIENCES, UNIVERSITY OF ALBERTA, EDMONTON, ALBERTA T6G 2E3, CANADA 4INSTITUTE OF GEOLOGY AND GEOPHYSICS, CHINESE ACADEMY OF SCIENCES, BEIJING 100029, CHINA ABSTRACT Early Jurassic granitoids are widespread in the Lesser Xing’an–Zhangguangcai Ranges, providing excellent targets to understand the late Paleozoic to early Mesozoic tectonic framework and evolution of Northeast China, especially the Jiamusi block and its related structural belts. In this paper, we present new geochronological, geochemical, and isotopic data from the granitoids in the Lesser Xing’an–Zhang- guangcai Ranges to constrain the early Mesozoic tectonic evolution of the Mudanjiang Ocean between the Jiamusi and Songnen blocks. Our results show that the granitic intrusions in the Lesser Xing’an–Zhangguangcai Ranges are mainly composed of syenogranite, mon- zogranite, granodiorite, and tonalite, which have crystallization ages from 196 to 181 Ma. Their geochemical features indicate that these Jurassic intrusions are all high-K calc-alkaline I-type granites with metaluminous to weakly peraluminous compositions. These granitoids are characterized by enrichments in large ion lithophile elements (e.g., Ba, Th, U) and light rare earth elements and depletions in high field strength elements (e.g., Nb and Ta) and heavy rare earth elements, which are typical for continental arc–type granites. The sources of these granitoids were likely derived from juvenile Mesoproterozoic to Neoproterozoic crustal materials (e.g., metabasaltic rocks). Inte- grated with data from regional coeval magmatism, metamorphism, metallogeny, and structure, our new data suggest that the granitoids in the Lesser Xing’an–Zhangguangcai Ranges were probably formed in an active continental margin setting, which fits well in our previ- ous model of Early Jurassic westward subduction of the Mudanjiang Ocean between the Jiamusi and Songnen blocks. LITHOSPHERE; v. 11; no. 6; p. 804–820; GSA Data Repository Item 2019406 | Published online 4 November 2019 https://doi.org/10.1130/L1099.1 INTRODUCTION of these granitoids, there exists strong debate on blocks in the Early Permian, and its subduction the tectonic affinity of these granitoids, especially occurred during the Late Triassic–Early Jurassic Granitoid rock, one of the principal compo- for those in the Lesser Xing’an–Zhangguangcai (Ge et al., 2016; Wu et al., 2011; W.L. Xu et al., nents of continental crust, plays an important Ranges (LXZR) (Ge et al., 2017, 2018; Liu 2013b). Such a large ocean with a life span of role in exploring the formation, evolution, and et al., 2017a; M.J. Xu et al., 2013a; Wu et al., more than 140 m.y. implies that the Mudanjiang reworking of continental crust (Hu et al., 2016; 2011; Zhao et al., 2018; Zhu et al., 2017). The Ocean was probably a branch of the Paleo– Wu et al., 2011). It has been evidenced that well-developed late Paleozoic to early Mesozoic Pacific Ocean (Dong et al., 2017; Ge et al., 2017, granitoid rocks formed at distinct evolutionary granitoids in the LXZR are some of the most 2018; Wu et al., 2011; Zhao et al., 2018; Zhu et stages of an orogenic belt have different geologi- prominent products of the regional tectonic al., 2017). Consequently, increasing numbers of cal and geochemical characteristics (Barbarin, reorganization and amalgamation between the studies propose that the granitoids in the LXZR 1999; Pearce et al., 1984). Thus, the study of Jiamusi and Songnen blocks (Ge et al., 2017, were genetically related to the subduction of the granitoids can help to explore the related tec- 2018; Liu et al., 2017a; Wu et al., 2011). However, Mudanjiang Ocean (Dong et al., 2017; Ge et al., tonic environments and better understand crustal the formation mechanism of these granitoids is 2017, 2018; Wu et al., 2011; Zhao et al., 2018; growth and tectonic evolution on Earth (Maniar still controversial. On one hand, some previous Zhu et al., 2017). and Piccoli, 1989; Wu et al., 2011). views suggested that these granitoids could have The controversial tectonic affinity of the Northeast China (NE China) is characterized formed as a result of delamination following the LXZR granitoids further leads to ambiguity by exposure of large volumes of granitic intrusions orogenic collapse of the Central Asian orogenic in the early Mesozoic tectonic model of the with emplacement ages from the Paleozoic to belt (Meng et al., 2011; W.L. Xu et al., 2013b). contacting Jiamusi block at a regional scale. Mesozoic (Wu et al., 2011). Despite intensive On the other hand, more recent studies, with Several tectonic models have been proposed for geochronological and geochemical examinations evidence from the Heilongjiang Complex, reveal the Jiamusi block, including (1) postcollision that an ancient ocean, namely, the Mudanjiang extension of the southeastern Central Asian *Corresponding author: [email protected] Ocean, existed between the Jiamusi and Songnen orogenic belt (Guo et al., 2015; Meng et al., Geological© 2019 The SocietyAuthors. of Gold America Open |Access: LITHOSPHERE This paper | Volume is published 11 | underNumber the 6 terms| www.gsapubs.org of the CC-BY-NC license. 804 Downloaded from http://pubs.geoscienceworld.org/gsa/lithosphere/article-pdf/11/6/804/4873372/804.pdf by guest on 27 September 2021 MAO-HUI GE ET AL. | Mesozoic tectonic evolution of the Jiamusi block RESEARCH 116˚ 120˚ 124˚ 128˚ 132˚ 136˚ 40° 60° 80° 160° Kamchatka A Russia XXS: Xinlin-Xiguitu suture B Siberia HHS: Heihe-Hegenshan suture East Europe MYS: Mudanjiang-Yilan suture Belt Central -Okhotsk SXCYS:Solonker-Xar-Moron- Mongol China s UzbekiastanKazakhstan Changchun-Yanji uture Asian Mongolia Sikhote-Alin 52˚ Belt 52˚ N Kyrgyzstan Sea of 40° Japan F1: Jiamusi-Yilan fault Tajikistan Orogenic China Japan Xinlin - North China F2: Dunhua Mishan fault Tarim Craton F3: Nenjiang-Balihan fault India Pacific Ocean F4: Songliao Basin Central fault F5: Yuejinshan fault Erguna Block XXS Heihe Xiguitu Xing’an Block Lesser Nenjiang Xing ' 48˚ an 48˚ Range Nadanhada Songnen Block terrane MYS Range F5 an ' Jiamusi Block Yilan Xing Range F3 Mishan N Great F4 Songliao Basin HHS F1 44˚ Changchun 44˚ Zhangguangcai F2 Keshenketengqi 0 100 200km SXCYS Dunhua Yanji Kaiyuan Elevation (m) Chifeng 0 1000 2000 E116˚ 120˚ 124˚ 128˚ 132˚ 136˚ Figure 1. (A) Tectonic setting of the Central Asian orogenic belt (CAOB; modified from Şengör et al., 1993) and surrounding area. (B) Tectonic division of NE China, with the major blocks, sutures, and faults (modified from Liu et al., 2017b; Ryan et al., 2009). 2011; Xu et al., 2009), (2) a back-arc extensional Our new data not only put new constraints on the formed by collision of multiple microcontinents. setting resulting from bipolar subduction of age, source, and petrogenesis of the granitoids, These microcontinents (also called blocks or the paleo–Pacific plate beneath the Eurasian but they also provide important insights into terranes; e.g., the Erguna, Xing’an, Songnen, and continent in the east and the Mongol-Okhotsk the tectonic processes related to the subduction Jiamusi blocks and the Nadanhada terrane from Ocean plate beneath the Erguna Massif in the of the Mudanjiang Ocean to form the LXZR west to east) are currently separated by major north (M.J. Xu et al., 2013a; W.L. Xu et al., between the Jiamusi and Songnen blocks. faults (Fig. 1B; Ge et al., 2016; Wilde et al., 1997, 2013b; Yu et al., 2012), as well as long-lasting 2003; W.L. Xu et al., 2013a; Zhou et al., 2009). westward subduction of the Mudanjiang Ocean GEOLOGICAL SETTING AND SAMPLE The Songnen block primarily is composed beneath the Songnen block (Ge et al., 2016, DESCRIPTIONS of the southern Great Xing’an Range, Songliao 2017, 2018; Liu et al., 2017a; Zhu et al., 2017). Basin, and LXZR (HBGMR, 1993; Wu et To further constrain the tectonic model Geological Background al., 2011). The southern Great Xing’an Range of the Jiamusi block, we present whole-rock contains large volumes of Mesozoic volcanic geochemistry, zircon U-Pb dating, and Lu-Hf NE China, located in the eastern part of the rocks and granitoids (Wu et al., 2011), while isotope results of the granitoids from the LXZR. Central Asian orogenic belt (Fig. 1A), was likely the Songliao Basin (formed during the late Geological Society of America | LITHOSPHERE | Volume 11 | Number 6 | www.gsapubs.org 805 Downloaded from http://pubs.geoscienceworld.org/gsa/lithosphere/article-pdf/11/6/804/4873372/804.pdf by guest on 27 September 2021 MAO-HUI GE ET AL. | Mesozoic tectonic evolution of the Jiamusi block RESEARCH 3 N124°-125° A B E128° 130° 132° 134° Relative probability Relative F3 2 Terrane Nadanhada 48° Number 1 N48° Yichun 0 N126°-127° Yuejinshan 4 Fig. 3a Complex belt Relative probability Relative Hegang 3 Number 2 Jiamusi Tieli Fig. 3b F4 1 0 Jiamusi block 46° N128°-129° 6 Yilan 5 probability Relative 46° F1 Hulin 4 Mishan Number 3 2 1 0 N130°-131° F2 0 50 100 km 4 3 probability Relative Songnen- Mesozoic Granitoids Zhangguangcai Mudanjiang Late Paleozoic Granitoids Number 2 Range Massif Heilongjiang Complex 44° 1 Mashan Group 44° Faults 0 160 200 240 280 (Ma) 128° 130° 132° Figure 2. (A) Zircon U-Pb crystallization ages of granitoid rocks in the Lesser Xing’an–Zhangguangcai Ranges (LXZR) and surrounding area (modified from Ge et al., 2018). (B) Distribution of magmatic rocks in the LXZR and surrounding areas, NE China (modified from Wu et al., 2011).