Zircon U–Pb and Lu–Hf Isotopic and Whole-Rock Geochemical Constraints on The
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Precambrian Research 233 (2013) 297–315 Contents lists available at SciVerse ScienceDirect Precambrian Research jou rnal homepage: www.elsevier.com/locate/precamres Zircon U–Pb and Lu–Hf isotopic and whole-rock geochemical constraints on the protolith and tectonic history of the Changhai metamorphic supracrustal sequence in the Jiao–Liao–Ji Belt, southeast Liaoning Province, northeast China a,∗ a b a En Meng , Fu-Lai Liu , Ying Cui , Jia Cai a Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China b School of Earth and Space Sciences, Peking University, Beijing 100871, China a r a t i c l e i n f o b s t r a c t Article history: The Changhai metamorphic supracrustal rocks, located in the eastern–central part of the Jiao–Li–Ji Belt Received 3 February 2013 in the North China Craton (NCC), are composed mainly of various garnet–mica schists, along with minor Received in revised form 4 May 2013 quartzites and marbles. This study presents whole-rock major and trace element data, zircon U–Pb dates Accepted 16 May 2013 and Hf isotope data for these rocks in order to constrain their protolith age and provenance, and discuss Available online 23 May 2013 the tectonic implications. Geochemical results indicate that the source rocks were mainly granitoids with a possible minor contribution from clastic sediments with an active continental margin signature. Detrital Keywords: zircons have U–Pb age peaks at approximately 1887, 2174, 2552, 2765, and 3212 Ma, εHf values of −11.1 Metamorphic supracrustal rocks C to +13.0, and three major time windows of average continent crustal model ages (T ) of 2.04–2.33, Detrital zircon U–Pb–Hf isotopes DM Geochemistry 2.48–2.56, and 2.72–2.93 Ga. Besides, these units also contain significant numbers of concordant meta- Protolith morphic zircons that yielded a peak age of ca. 248 Ma, indicating that the region was modified by an Tectonic implications early Triassic tectono-thermal event. These results suggest that sediments of the Changhai metamorphic Northeast China supracrustal rocks were mainly sourced from nearby basement granitoid rocks and, to a lesser extent, from Paleoproterozoic metamorphosed strata such as the North and South Liaohe groups. Furthermore, the source rocks of the magmatic zircons analyzed in this study appear to have originated from inter- action between old continental crust and juvenile material. The youngest concordant zircon age peak at 1879 Ma coincides with the timing of formation of regionally widespread granitoids, mafic igneous rocks, and metamorphism of the South Liaohe and Ji’an groups in the Jiao–Liao–Ji Belt, and suggest that the sed- imentary protoliths of the Changhai metamorphic supracrustal rocks were deposited after this time. The results indicate that the Archean Liaobei–Jinan Complex in the north and the Liaonan–Nangrim Complex in the south were already a single continental block by 1887 Ma, and that the Changhai metamorphic supracrustal rocks were deposited at an active continental margin. © 2013 Elsevier B.V. All rights reserved. 1. Introduction Khondalite Belt resulted from collision between the Yinshan and Ordos blocks to form the Western Block at ca. 1.95 Ga (Zhao et al., In the past two decades, major achievements from structural, 2005, 2010a; Santosh et al., 2006, 2007a, 2007b, 2009a,b, 2012; Xia metamorphic, geochemical, and geochronological studies on the et al., 2006a, 2006b, 2008; Yin et al., 2009, 2011; Santosh and Kusky, basement rocks of the North China Craton (NCC), which is the 2010; Li et al., 2011a; Peng et al., 2011, 2012a,b; Wang et al., 2011a; largest and oldest craton in China, have identified three major Dan et al., 2012; Guo et al., 2012), whereas the Trans-North China Paleoproterozoic mobile belts (Khondalite Belt, Trans-North China Orogen resulted from the amalgamation of the Western and East- Orogen, and Jiao–Liao–Ji Belt) in the western, central, and east- ern blocks to form the coherent basement of the NCC at ca. 1.85 Ga ern parts of the craton, respectively (Fig. 1a; Zhao et al., 2000, (Zhao et al., 2001, 2005, 2006a, 2006b, 2007, 2008a,b; Guo et al., 2001, 2005; Zhao, 2009). Now there is a broad agreement that the 2002, 2005; Wilde et al., 2002; Kröner et al., 2005, 2006; Zhang et al., 2006, 2007, 2009, 2012; Li et al., 2010; Liu et al., 2011a,b, 2012a,b,c,d). This research has provided a coherent understanding ∗ of the timing and tectonic processes involved in these Paleopro- Corresponding author at: Institute of Geology, Chinese Academy of Geological Sciences, 26 Baiwanzhuang Street, Beijing 100037, China. Tel.: +86 10 68999960; terozoic orogenic events and of the pre-collisional history of the fax: +86 10 68992873. Khondalite Belt and Trans-North China Orogen (Zhao et al., 2001, E-mail addresses: [email protected], [email protected] 2002, 2005, 2007, 2010b, 2012; Liu et al., 2002, 2006, 2007; Wilde (E. Meng), lfl[email protected] (F.-L. Liu), [email protected] et al., 2002; Zhai and Liu, 2003; Zhai et al., 2005; Zhai and Santosh, (Y. Cui), [email protected] (J. Cai). 0301-9268/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.precamres.2013.05.004 298 Legends 115 E 120EE 125 130 E Liaonan-Nangrim complex North Liaohe Assemblage Southern Jilin Laoling Liaobei-Jinan complex Assemblage Duolun B Western Northern Liaoning Ji elt Exposed basement in other Liaoning Ji`an r egion of the Eastern Block Assemblage Western rogen Post-Palaeoproterozoic Block O 40 N cover in the Jiao-Liao-Ji hina Nangrim Belt C Liao Macheonryeong Fenzishan,North Liaohe and Eastern Hebei Assemblage Laoling Groups and associated E. Palaeoproterozoic granites in ans-North Pyeonrand Meng Tr Beijing Southern Liaoning South Liaohe the Jiao-Liao-Ji Belt Assemblage Belt et a Jingshan,South Liaohe,Ji’an al. Se a Se and Wuhe Groups and associated / Yellow ohai Precambrian Palaeoproterozoic granites in B Imjingang the Jiao-Liao-Ji Belt iao Fenzishan Seoul Shijiazhuang J Assemblage Changhai Supercrustal Rcoks, Belt traditionally regared as the South Research Liaohe Group-Ji Belt (in Fig.2) Eastern Block Fig.Fig.2 Gyeonggi elt B Macheonayeong Group (North Eastern Shandong Korea) in the Jiao-Liao-Ji Belt Jingshan 233 (2013)297 in the Jiao-Liao-Ji Belt Assemblage eongnam 35 N Faults Western Shandong Y elt 105 00' B – ( a ) a 315 East China Se Wuhe Assemblage N 35 00' b 0 200km N Xinyang Su-Lu Ultrahigh-pressure 0 1000km ( b ) Fig. 1. Tectonic setting of the NCC (a) and regional map of the Precambrian geology of the Eastern Block in the NCC, modified after Zhao et al. (2005). The location of Fig. 2 is indicated by the rectangle. WB – Western Block; EB – Eastern Block; TNCO – Trans-North China Orogen; YB – Yinshan Block; OB – Ordos Block. E. Meng et al. / Precambrian Research 233 (2013) 297–315 299 122 30' 122 45' 123 00' 40 ( a ) 00' Shicheng iver Zhuanghe island ( b ) N R 39 iliu 39 30' B 39 30' Pulandian Pikou 30' N Sea ohai B b 39 Dalian 00' Yellow Sea 0 30km Legends 39 Exposed basement 39 20' Dachangshan island in the Eastern Block 20' Post-Palaeoprotero Changhai Xiaochangshan -zoic cover in the island Jiao-Liao-Ji Belt Changhai Supercrustal DD10-1 Rocks, traditionally r egared as the South Liaohe Group Towns 39 Sampling location 39 10' Sea 10' Yellow Guanglu island Haiyang island Z hangzi island HY06-1 HY03-1 0 10km HY05-1 DD23-3 HY05-2 DD20-1 HY01-1 122 30' 122 45' 123 00' Fig. 2. Tectonic setting (a) and map of the Precambrian geology (b) of Changhai in southeast Liaoning province, including representative sample locations (modified after LBGMR, 1989). (For interpretation of the references to color in this figure, the reader is referred to the web version of the article.) 2011; Kröner et al., 2005, 2006; Santosh et al., 2006, 2007a, 2007b, and in adjacent regions, particularly with regards to the nature of 2009a; Wan et al., 2006; Xia et al., 2006a, 2006b, 2008, 2009; Zhang their protoliths and their tectonic nature. et al., 2006, 2007, 2009; Yin et al., 2009, 2011; Peng et al., 2011; Zhao The Changhai Islands in the southern Liaoning Province of and Guo, 2012; Zhao and Cawood, 2012). northeast China are located in the southeastern Liaoning–Nangrim However, the formation and evolution of the Jiao–Liao–Ji Complex (Nangrim Block), locating in the eastern part of the central Belt remain controversial, despite extensive geochronological and Jiao–Liao–Ji Belt (Fig. 2a). Our recent investigations and previous geochemical research focused on the metamorphic supracrustal, studies have revealed voluminous granitoids and metamorphic granitoid, and volcanic rocks within the belt (e.g., Li et al., 2001a, supracrustal rocks in this region (Meng et al., 2012). Due to the 2003, 2005, 2006, 2011b,c,d, 2012; Faure et al., 2004; Luo et al., lack of exposure in the region between the islands and the Chi- 2004, 2008; Zhao et al., 2005, 2012; Lu et al., 2006; Li and Zhao, nese mainland, the igneous and metamorphic ages, petrogenesis, 2007; Tam et al., 2011; Zhao and Guo, 2012). Some researchers con- and tectonic setting of these rocks are not well constrained. In sider that this belt represents a continent–arc–continent collisional this study, we carried out a detailed petrological, geochemical, belt, along which the Archean Liaobei–Jinan Complex (Longgang geochronological (zircon U–Pb), and isotopic (zircon Hf) data for Block) in the north and the Liaonan–Nangrim Complex (Nan- the Changhai metamorphic supracrustal rocks. These new data, grim Block) in the south collided to form a coherent block in in combination with available regional geological data, are used the Paleoproterozoic (Hu, 1992; Bai, 1993; Bai and Dai, 1998; He to constrain the depositional age and the nature of the protolith, and Ye, 1998a,b; Faure et al., 2004; Lu et al., 2006).