Early Continent Evolution of the North China Craton

By Lei Zhao

Early Continent Evolution of the North China Craton discusses the tectono-thermal regimes of the early continental crust in the North China Craton (NCC) from the Hadean to the early Paleoproterozoic, reconstructing the evolutional framework, and facilitating comprehensive understanding of the early continent evolution of the NCC. The book systematically summarizes the Neoarchean metamorphism of the NCC and discusses the implications for the tectonic models of the NCC, through compiling evolutional information of the Hadean to the early Paleoproterozoic sequences in the NCC. This allows for comprehensive summarizations and discussions on the tectonic framework of the NCC during this critical period.

Researchers, academics and students in geology (especially Precambrian Geology), geomorphology, geophysics and geological engineering will benefit from using this book in applying tectonic models to other cratonic blocks globally, and will understand evolutional information of the largest and oldest cratonic block in China.

• Completely covers all key issues and research frontiers of the early continental evolution of the North China Craton (NCC), from the Hadean to the early Paleoproterozoic
• Systematically summarizes the Neoarchaean metamorphism of the NCC and discusses the implications for tectonic models
• Includes discussion on controversial views on tectonic regimes of the NCC during the Archean to early Paleoproterozoic, with objective conclusions

• Language: English
• Publisher: Elsevier Science
• Release date: Mar 27, 2024
• ISBN: 9780443138881

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Preface

Mingguo Zhai and Yanyan Zhou

The Earth is an evolving planet, whose evolution is achieved through major geological events, including the generation of continental nuclei, the enormous growth, the formation of microblocks, and the crustal stabilization (cratonization) during the Hadean to Archaean, accompanied by the global surface environmental upheavals, and the changes and transitions of oxygen concentration in the atmosphere and ocean at the end of Neoarchean and early Paleoproterozoic, after that it was followed by the initiation of modern plate tectonics, the Neoproterozoic-Cambrian explosion of life, and the transformation of energy and mineral resources. Therein, the major Precambrian geological events particularly recorded more than 90% of the Earth’s evolutionary history. More than 80% of the continental crust was formed in the Precambrian, and the remaining ~20% of the continental crust is the product of the oceanic–continental and crust–mantle interactions during the Phanerozoic, in which the contribution of the ancient continental crust forming and recycling has not been well studied. Therefore the major Precambrian geological events are undoubtedly the key, frontier, and basic disciplines for the study of continental evolution, mineralization, and Earth’s environment.

The North China Craton (NCC) is one of the most representative cratons in the world. It is also the largest one (1300,000 km²) with the longest formation and evolutional history in China. Its 2 billion years’ evolutional processes record almost all the major tectonic events during the early Earth’s evolution, creating excellent opportunities for exploring the mechanism of the early continental formation and Earth’s environment evolution.

The Precambrian tectonic evolution of the NCC can be divided into the following stages: the formation of continental nuclei during the Hadean to Archaean and the Meso-Neoarchaean (2.9–2.7 Ga) continental crustal growth and forming microcontinental blocks. The assembly of microblocks in the NCC at the end of the Neoarchaean (c. 2.5 Ga) was marked by typical tectonic-magmatic-metamorphic events, indicating the cratonization of the NCC. The most important events in the Paleoproterozoic were the Great Oxidation Event (2.4–2.0 Ga) and mobile/orogenic belts (1.97–1.85 Ga). The 1.97–1.85 Ga orogeny records high-grade granulite facies metamorphism. Middle-Neoproterozoic multistage rifts and material and structure adjustment of mantle crust has been termed the Earth Middle Age event, also known as the boring billion. Among them, the formation and growth of continental crust, the tectonic transition from thermotectonic regime to plate tectonic regime, the material cycle and metallogenic evolution, and the early Earth’s environment and origin life are the key scientific issues in the study of Precambrian geology.

Through years of effort, geologists have made important discoveries and systematic achievements. The representative research results include (1) founding the Hadean (>3.8 Ga) rock and material remnants and confirming several continental nuclei. (2) Based on the genetic studies of the 2.9–2.5 Ga volcanic basalts and TTGs (Tonalite-Trondhjemite-Granodiorite), multistages of continental crust growth and ~2.5 Ga cratonization in the NCC were determined. The tectonic framework of the early continental evolution has been established, especially the c. 2.5 Ga cratonization followed by the occurrence of 2.5–2.45 Ga high-grade metamorphism, granites, and basic dike swarms. (3) Reveling that the early Paleoproterozoic (2.5–2.2 Ga) evolutional processes of the NCC should be disintegrated into the continuing effects of the Neoarchean cratonization (2.40–2.42 Ga), plume-related mantle-crustal interaction (e.g., formation of 2.35–2.30 Ga komatiitic rocks and low-pressure (LP) TTG), and plume-triggered rifting initiation (2.42–2.20 Ga). Subsequently, there would be rifting development and a tectonic transition (2.20–2.05/2.00 Ga). (4) First, discovering 1.97–1.85 Ga high-pressure (HP) metamorphic rocks, including high-pressure granulites and regressive eclogites, marking the complete orogenic processes of continental subduction-collision-post-collision setting. The Paleoproterozoic continent evolutional processes are consistent with the global Paleoproterozoic orogenic event that developed across Africa, North America, South America, and Eurasia and are the tectonic-magmatic responses to the formation of the Columbia supercontinent. (5) Systematically summarizing multistage forming and reworking mechanism of the early continental crust, and proposing multistage cratonization. (6) Discussing the restriction of the Earth’s thermal regime on the tectonic evolution mechanism and putting forward the theoretical hypotheses of pre–plate tectonics, initial plate tectonics, and modern plate tectonics.

Up to now, there are still controversies about the evolutional mechanism of the early Precambrian continent in the NCC. For instance, the unclear genetic mechanism of paleo-ocean and high-temperature komatiites, lack of arc-related andesites, the kell-dome (greenstone belt–high-grade region) tectonic patterns, and the absence of modern plate tectonic key features (e.g., ophiolite, blueschist, ultra high-pressure (UHP) eclogite, and paired metamorphic zones) all indicate that the Archean (at least before Neoarchean) continents may not have been originated from plate tectonic systems, but from some kind of pre–plate tectonic systems, such as mantle plume, stagnant-lid thermal cavity, and other models. Therefore the establishment of a pre–plate tectonic system that can satisfactorily explain the origin and evolution of the Archean continents has become the top priority of current earth science research. Our recent research shows a three-stage plate tectonics transition model, which is the initial (I, Eo-plate Tectonics, ~2.9–2.5 Ga), the early (II, Early Plate Tectonics, 2.0–1.9 Ga), and the modern (III, Modern Plate Tectonics, from Neoproterozoic). I and II are different not only in scale but also in principle from modern plate tectonics (III), consistent with the evolution of the continental crust and lithosphere. Among them, the rock layers with negative buoyancy drag on the diving side are, respectively, banded iron formation, high-pressure granulite, and HP-UHP eclogite. Corresponding digital simulations and modeling are also reported.

However, whatever the model of tectonic systems, four geological processes need to be focused on (1) the petrogenesis of TTGs, their composition, and genetic mechanism change over time, as well as the maturation of the Precambrian continental crust and its reflection on the evolution of the Earth. (2) The lower cratonic crust is recycled and restructured under the mantle heating or crustal thickening, and the partial melted granitic melts migrate upward and locate in the middle and upper crust with enrichment of thermogenic elements. Metamorphic differentiation and partial melting are two basic factors of cratonization, which finally form a stable upper and lower crust. Global cratonization is the greatest event in Earth’s evolution, the effects of which have yet to be fully explained. (3) The formation mechanism of cratonic lithosphere. Existing knowledge indicates that the lithosphere has been gradually thinning from the early Archean to the present. The important changes in the structure and material composition of the lithosphere from Neoarchean to Paleoproterozoic (LNAPP) are the basis for the initiation of the modern tectonic system, which is termed the critical period of the lithosphere. How and why is the transformation of LNAPP the scientific frontier of training solutions? (4) The Earth’s surface environment transformed from an oxygen-free to an aerobic state Great Oxidation Event (GOE) during the Neoarchean and the early Paleoproterozoic. Meanwhile, the relationship between tectonic systems and the drastic environmental change of the Earth also needs to be further discussed.

This book comprehensively discusses the petrogenesis and tectono-thermal regimes of the Hadean to the early Paleoproterozoic continental crust in the NCC, including compilation of the petrogenetic information of the magmatic-metamorphic-sedimentary sequences and the tectonic settings of these rocks, and tries to reconstruct the evolutional framework of the continental crust of the NCC in the early Earth. A total of eight chapters are proposed as follows.

Chapter 1 gives a brief introduction to the generation and growth of the Precambrian continental crust of the NCC, including major geological processes, proposal models of continent evolution, and their tectonic settings. Chapter 2 focuses on the general geology of the Precambrian geology of the NCC, including the tectonic division of the microblocks, recent research achievements on the high-grade gneissic region and greenstone belt, the evolutional processes of the Archean multistage continental growth, and the late Archean cratonization. Chapter 3 expresses that the geological record of the first billion years of Earth’s history is vitally important for understanding the early evolution of our planet. The authors summarize the occurrence of Eoarchean to Paleoarchean rocks and zircons in the NCC, review their age and geochemical properties, and then discuss several important issues relating to the sources and nature of the Hadean-Paleoarchean crust worldwide. Chapter 4 illustrates that at least three major magmatic events (3.2–3.0 Ga, 2.9–2.8 Ga, ~2.5 Ga) at Mesoarchean time and two major metamorphic overprints (~2.8 Ga and ~2.5 Ga) are identified in the NCC. The authors introduce petrogenesis and evolutional relationships of a series of Mesoarchean-Neoarchean magmatism in the NCC. They may mark considerable diversification in both the nature and evolutional processes of the continental crust. Chapter 5 is about the crustal evolution of the NCC during the Neoarchean period and tries to reveal the continental evolution and the geological history of the NCC in 2.8–2.5 Ga. Chapter 6 presents the Neoarchean metamorphism in the high-grade greenstone belts and high-grade gneissic regions from the NCC. The authors systematically summarize the distribution, nature, extent, time duration, and P−T paths of Neoarchean metamorphism and further discusses the tectonic models of the NCC based on the metamorphic geological perspective. Chapter 7 describes that the Earth experienced fundamental tectonic transformation and paleoclimatic upheavals during the early Paleoproterozoic (2.5–2.1 Ga) following the Neoarchean cratonization. However, the tectonic framework of this crucial period is challenging to define precisely. This chapter carries on a comprehensive compilation of the 2.5–2.2 Ga magmatism-sedimentary sequences in the NCC, to provide key constraints on the Archean-Proterozoic transition. Chapter 8 describes different tectonic regimes of the NCC during the early Precambrian which may further update the understanding of the tectonic evolution of the NCC during the early history of Earth.

In a word, the original intention of writing is to introduce the research on the early continental evolution of the NCC to colleagues at home and abroad, hoping to arouse more discussions and suggestions, and then promote our research. Each chapter is written mainly by young scholars who will benefit from the writing and discussion. It is hoped that the study of the early evolution of the continent makes greater progress with the joint efforts of scientists from all over the world.

Chapter 1

Continental crust and general tectonic framework of the North China Craton: a synopsis

Jian–Li Kang¹,²,³, Mingguo Zhai⁴,⁵, Jinghui Guo⁴,⁵, Huichu Wang³, Yanyan Zhou⁴,⁶, Lei Zhao⁴,⁵, Peng Liou⁴ and Peng Peng⁵,⁷,    ¹School of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, P.R. China,    ²Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, P.R. China,    ³Tianjin Center, China Geological Survey (North China Center for Geoscience Innovation), Tianjin, P.R. China,    ⁴State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, P.R. China,    ⁵College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, P.R. China,    ⁶Innovation Academy of Earth Science, Chinese Academy of Sciences, Beijing, P.R. China,    ⁷China-Brazil Joint Geoscience Research Center, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, P.R. China

Abstract

The North China Craton (NCC) is one of the world’s oldest cratons with a few Eoarchean-Paleoarchean granitoids and supracrustal rocks occurred in the Anshan (Liaoning), Lulong (Hebei), and Xinyang (Henan) regions. There are a couple of the Mesoarchean terranes including Jiaobei (Shandong) and Lushan (Henan). The Neoarchean rocks especially the 2550–2500 Ma plutonic and supracrustal units dominated the basement, which widely accepted the 2500–2450 Ma metamorphism. The Paleoproterozoic metamorphose regions with high grades (amphibolite to granulite facies) distributed in two zones: one cross the western craton, and the other along the south–eastern margin of the eastern craton. Temporally, the two zones are limited in two narrow zones at 1965–1875 Ma, and then expanded into wide regions across much of the craton at 1875–1790 Ma, which are spatially correlated with the contemporaneous episodes of magmatism. These Paleoproterozoic metamorphism and magmatism are well-known as a result of orogenesis. Subsequently, the NCC has experienced multiple stages of rifting during 1800–800 Ma. In the Late Triassic to the Early Jurassic, the configuration of the craton in Eastern Asia resulted in a 15° clockwise rotation of the eastern portion of the craton along the Tanlu fault, right before the subduction of the Pacific plate to the east of the craton since the Jurassic.

Keywords

North China Craton; Tectonic framework; Archean units; Paleoproterozoic units; Metamorphism; Tanlu fault

1.1 General tectonic evolution of the North China Craton

The North China Craton (NCC) is one of a few cratons that reported rocks over 3.8 Ga in age on the planet Earth (Fig. 1.1), and one of the three major cratons of China (Fig. 1.2 and 1.3A). It has an area of 1,500,000 km² (Fig. 1.3B) and preserves crustal records back to 3.9 Ga (Liu et al., 2008; Wan et al., 2021) and has experienced cratonization in the Neoarchean which gave rise to widespread tonalite–trondhjemite–granodiorite (TTG) gneisses and greenstone belts, and extensive Paleoproterozoic orogenic events with metamorphism up to ultrahigh-temperature or high-pressure granulite facies (Guo et al., 2012; Kusky et al., 2007; Liu et al., 2012a; Santosh et al., 2007, 2013; Zhai et al., 1992; Zhao, 2014; Zhao et al., 2001, 2005). The Archean domains are commonly composed of volcano–sedimentary successions (greenstone belts/supracrustal series, including komatiites, basalts, pillow lavas, and banded iron formations/BIFs) and TTG gneisses, diorites, and granites (Fig. 1.3B). Separated by the Cenozoic faults, there are numbers of the Neoarchean terranes, and many of them have been metamorphosed to relatively high-grade (high-amphibolite to granulite facies), except for a few, for example, the Taishan (western Shandong) and Zhongtiao terranes (greenschist to low-amphibolite facies: Wan et al., 2015). Most terranes were affected by an End Neoarchean (2.50–2.45 Ga) regional anticlockwise metamorphism up to granulite facies (Wan et al., 2015); and some terranes have been also overprinted by a Paleoproterozoic high-grade metamorphism, especially along the margins of both the Western and Eastern NCC (Peng et al., 2014).

Figure 1.1 Major cratons of the planet Earth.

Figure 1.2 Map showing the localities where the Hadean zircons (≥4.0 Ga, red triangles) and Eoarchean rocks (≥3.6 Ga, blue triangles) have been identified. Red triangles: 1—Liangdang, Gansu province; 2—Zhongning, Ningxia province; 3—Labashan region of the eastern Hebei area; 4—Huoqiu Complex, southeastern margin of the NCC; 5—Longquan county, Zhejiang province; 6—Tanghu county, Jiangxi province; 7—Nanning, Guangxi province; 8—Shenwan county, Guangdong province; 9—Buring county, Tibet province; 10—East Junggar basin, Xinjiang province. Blue triangles: 1—Anshan Complex in Liaoning province; 2—3.78 Ga granodioritic gneisses in eastern Hebei province; 3—3.82 Ga felsic granulite xenoliths in Xinyang region, Henan province; 4—3.72 Ga Aktash gneisses in Tarim Craton, Northwest China; 5—3.8 Ga Muzidian gneisses in the northern South China block ( Liou et al., 2023). Source: From Liou, P., Guo, J., Peng, P., Zhai, M., 2023. Geological evolution of the North China Craton in the first billion years of Earth’s history. Earth-Science Reviews https://doi.org/10.1016/j.earscirev.2023.104608.

Figure 1.3 Geological map showing the Archean–Paleoproterozoic domains in the North China Craton. (A) Tectonic framework of China; (B) Archean–Paleoproterozoic terranes of the North China Craton.

It has been well established that the Eastern and Western NCC were finally collided at ca. 1.8 Ga (Guo et al., 2012; Kusky et al., 2007; Liu et al., 2004; Trap et al., 2007, 2012; Zhai and Santosh, 2011; Zhai and Peng, 2007; Zhang et al., 2009; Zhao et al., 2001, 2005), resulting in its configuration into the supercontinent Columbia/Nuna (Zhao et al., 2002). Before its final assembly, three mobile belts/rift basins were developed, that is, the Liaoji belt to the east, the Jinyu belt in the middle, and the Fengzhen belt to the west (north) since ca. 2.35 Ga (Zhai and Peng, 2007), which evolved into three orogens, the Jiao-Liao-Ji, the Trans-North China, and the khondalite orogenic belts, during 2.05–1.8 Ga, respectively (Zhao et al., 2005). These belts have also been referred as front-arc or back-arc basins/rifts during 2.35–1.85 Ga (e.g., Liu et al., 2007, 2016c; Trap et al., 2012; Wu et al., 2022a; Yuan et al., 2017). Nevertheless, Kusky et al. (2007) have proposed the metamorphic regions of the khondalite belt and the northern portion of the so-called Archean Central Orogenic belt [much overlapped with the Trans-North China orogen (TNCO)] defined by Zhao et al. (2005) as the overprinted Paleoproterozoic Inner Mongolia-North Hebei orogen. Another work based on the distribution of igneous suites defines the 2.3–2.05 Ga magmatic rocks in the Liaoji and Jinyu belts as the unique Hengling rift/magmatic belt, while the 2.05–1.85 Ga magmatic rocks in the Fengzhen and Liaoji belts have been referred as the Xuwujia and Korean arc/magmatic belts, respectively (Peng et al., 2014).

In the NCC, there are some sill/dyke swarms and associated igneous units during 2250–2050 Ma, which are relic portions of the LIPs at ca. 2220 Ma (Taihua-Yejishan LIP) (Li et al., 2022; Sun et al., 2017; Zhou and Zhai, 2022), ca. 2185 Ma (Gaofan LIP) (Bi et al., 2018; Lan et al., 2015; Li et al., 2015; Peng et al., 2017a, 2023; Wilde, 2014), ca. 2145 Ma (Hengling LIP) (Peng et al., 2012a), ca. 2120 Ma (Haicheng LIP) (Wang et al., 2016), ca. 2090 Ma (Zanhuang LIP) (Peng et al., 2017a; Wang et al., 2020c), and the ca. 2060 Ma (Yixingzhai LIP) (Peng et al., 2012a; Cai et al., 2022), respectively (Fig. 1.4). This LIP peak in the NCC is coincident with the global LIP peak, and it is also coincident with tremendous organic rich strata during 2.25–2.05 Ga, which may have a causal relationship with the development of the Great Oxidation event (Peng et al., 2023). It is well-known that this group of events was followed by another peak of LIPs during 1800–1600 Ma (Peng et al., 2022b) (Fig. 1.4). At 1770 Ma the giant Taihang dyke swarm traverses the whole craton, after which all tectonic activity ceased (Peng et al., 2022b). Subsequently, it was followed by episodes of dyke swarm, rifting, and platform deposition (Lu et al., 2008). It has been proposed that these 1800–1600 Ma LIP units in the NCC, as well as many of those global units, may be vestiges of five LIPs (e.g., ca. 1785 Ma Xiong’er, ca. 1770 Ma Taihang, ca. 1730 Ma Miyun, ca. 1680 Ma Laiwu, ca. 1630 Ma Taishan), which came from a same plume during the assembly of the Columbia supercontinent, and thus present as a late Paleoproterozoic hotspot track (Peng et al., 2022b). There are also 1320–1230 Ma LIPs (1320 Ma Yanliao and 1230 Ma Licheng), 950–890 Ma LIPs (940 Ma Baengneyong, 920 Ma Dashigou-Niutishan and 900 Ma Pingshan), 840–775 Ma LIPs (820 Ma Qianlishan and 775 Ma Laolijia), along with the development of the Yanliao and Xuhuai rift systems in the craton (Peng et al., 2022b) (Fig. 1.3).

Figure 1.4 The major Precambrian magmatic (large igneous province, LIP) and associated rift/arc events in the North China Craton. Revised after Peng et al. (2022a): The 2220–2060 Ma LIPs, the 1795–1630 Ma LIPs, and the 950–890 Ma LIPs are updated from Peng et al. (2022b,2023), and Cho et al. (2023), respectively.

During the Phanerozoic, there were orogenic events surrounding the craton, resulting in the configuration of the NCC in eastern Asia, and then the NCC was under the affection of the western Pacific tectonic region, when the eastern NCC has largely lost its lithospheric mantle keel (also known as the destruction of the NCC; c.f. Menzies, 1997, 2007; Xu, 2001; Griffin et al., 1998; Wu et al., 2006; Zhu et al., 2012). Another feature during the configuration of the NCC in eastern Asia is the movement of the Tanlu fault, which offsets eastern parts of the craton including terranes of the Jiaobei, Liaodong, Liaobei, Jinan, and North Korean (Rangnim) (Fig. 1.5). Although it has been controversial, a recent study suggests that a ~15° clockwise rotation of this portion that resulted in a up to 450 km offset along the fault occurring in the Late Triassic–Early Jurassic (Peng et al., 2022c). This has distinctly shaped the framework of the basement: For example, after the recovering of this rotation, the regions with 3.9–3.8 Ga TTGs and the best-preserved dome and keel structure in the craton are as close as possible, and the 2.7 Ga and the 2.9 Ga TTG–supracrustal rocks featured terranes neighbors each other (ca. 2.7 Ga Zhongtiao–western Shandong–Liaonan region and the ca. 2.9 Ga Lushan–Jiaobei region) (Fig. 1.5).

Figure 1.5 The framework of the basement of the North China Craton after the reconstruction of the major offset of the Tanlu fault in the Mesozoic. Revised after Peng et al. (2022c).

1.2 Major Archean and Paleoproterozoic units

1.2.1 Eoarchean–Paleoarchean (4030–3200 Ma) units

The formation and early evolution of the Earth present formidable challenges, primarily attributable to the constrained accessibility of ancient rocks and the complicate post-formation tectonic recycling resulting in a scarcity of rock records back to Paleoarchean. Only in a few locations such as Greenland, Antarctica, North America, and the Anshan region of China are there limited outcrops of these rocks (Black et al., 1986; Kinny, 1986; Liu et al., 1992; Song et al., 1996; Wan et al., 2005) (Fig. 1.1). The Acasta gneiss from Canada, dated at ca. 4.0 Ga, represents the oldest known preserved rocks on Earth (Bowring and Williams, 1999). Jack Hills in Western Australia is currently the location where the oldest discovered zircon grains, dating back to approximately 4.4 Ga (Wilde et al., 2001), whose internal structure and oxygen isotope composition provide evidence of granite magmatism and the presence of water (Mojzsis et al., 2001). And the discovery of diamond inclusions within detrital zircons suggests that continental crust had already attained a significant thickness (Menneken et al., 2007). According to geochronology, the oldest rocks and zircons are spatially shown in Fig. 1.6. The oldest rocks in China mainly occurred in Anshan (Liaoning) (Liu et al., 1992; Song et al., 1996; Wan et al., 2005; Wang et al., 2015c), Lulong-Qian'an (Wan et al., 2021) (eastern Hebei), and Xinyang (Zheng et al., 2004) (Fig. 1.2).

Figure 1.6 Simplified geological map of the North China Craton (NCC) showing the distribution of oldest rocks and zircons (>3.2 Ga). Updated after Wan et al. (2023a). Blue hollow square: rock age; red solid square: detrital or xenocrystic zircon age. BB, Bengbu; CAD, Central Ancient Domain; CD, Chengde; DB, Debusige; DF, Dengfeng; DQS, Daqingshan; DY, Dongying; EAD, Eastern Ancient Domain; EH, eastern Hebei; ES, eastern Shandong; FP, Fuping; HA, Huai’an; HC, Hexi Corridor; HQ, Huoqiu; HS, Hengshan; JZ, Jiaozuo; LL, Lüliang; LS, Lushan; MY, Miyun; NL, northern Liaoning; SAD, Southern Ancient Domain; SJ, southern Jilin; SL, southern Liaoning; SY, Sangyuan; WL, western Liaoning; WS, western Shandong; WT, Wutai; XQL, Xiaoqinling; XY, Xinyang; YS, Yinshan; ZH, Zanhuang; ZJK, Zhangjiakou; ZT, Zhongtiao.

Table 1.1 lists the outcrops of rocks and zircons with ages over 3.2 Ga. In Anshan, the 3.8–3.3 Ga rocks have been found in Dongshan, Baijiafen, Shengousi, Guodishan, and Hujiamiao. Geochronology provides evidence of magmatic events occurring at ca. 3.8, 3.6, 3.45, and 3.3 Ga in these localities. The Dongshan Complex consists of ca. 3.8 Ga layered trondhjemitic gneiss and is cut by trondhjemitic and pegmatitic veins (Song et al., 1996) and quartz diorite gneisses (Wan et al., 2005), 3.7–3.8 Ga tonalite gneiss, ca. 3.47 Ga tremolite and amphibolite, ca. 3.3 Ga diorite and tonalite gneiss (Song et al., 1996; Zhou et al., 2007), ca. 3.4 Ga Chentaigou supracrustal rocks (Song et al., 1994), and ca. 3.3 Ga Chentaigou granite (Wan et al., 1997) and occurred as an enclave in ca. 3.1 Ga Lishan trondhjemite. The Baijiafen Complex is ca. 700 m long and 10–30 m wide, showing fault contacts with granite in the southwest and Chentaigou supracrustal rocks in the northwest (Wu et al., 2008). It is a trondhjemitic gneiss cut by several granitic veins. SHRIMP U-Pb dating yields multistages of magmatism taking place at ca. 3.8 Ga, 3.7–3.6 Ga, and 3.3–3.1 Ga, indicating crustal recycling (Wu et al., 2008). The Shengousi Complex is the best exposure in Anshan area, with a ca. 50 m long and up to 10 m high section, and mainly composed of banded trondhjemitic gneiss (3.77 Ga), occurring with the second generation of trondhjemitic rocks (3.45 Ga), a composite suite of iron-enriched mafic dykes (3.33 Ga) with broadly coeval felsic veins (3.31 Ga), and monzogranite (3.13 Ga) (Wan et al., 2012a). The Hujiamiao Complex is mainly composed of mylonitized trondhjemitic gneiss with minor biotite schist and metagabbro. Geochronology suggests trondhjemitic rocks formed at 3.8–3.1 Ga (Wan et al., 2023b).

Table 1.1

The oldest trondhjemitic rocks at 3.8 Ga contain some younger zircons at 3.3 Ga. Someone considered the trondhjemitic gneiss crystallized at 3.3 Ga and inherited 3.8 Ga zircons from the origin (Wu et al., 2008); others suggested that the gneisses had experienced strong ductile deformation and were injected by migmatites containing igneous components of anatexis of 3.8 Ga rocks at 3.3 Ga (Wan et al., 2019). However, Wang et al., (2015c) concluded that the trondhjemitic gneiss was emplaced at 3.8 Ga and there are some younger leucosome. The ca. 3.8 Ga trondhjemitic gneisses show features of crustal recycling with probably mantle addition (Wan et al., 2019).

Eastern Hebei and Xinyang are the other two localities with the oldest rocks (Fig. 1.7). The Caozhuang supracrustal rocks in Huangbaiyu (Qian’an), are mainly composed of quartzite, para-amphibolite, garnet-biotite gneiss, calc-silicate rock, marble, fine-grained biotite gneiss, and BIF, deposited at 2.5–3.4 Ga based on the ages of metamorphic and detrital zircons (Wan et al., 2019). And there are some gneissic tonalite with age 3.3–3.2 Ga as enclaves within 2.5 Ga granite (Nutman et al., 2011). The depositional age of fuchsite quartzites is constrained between 3.55 and 3.3 Ga (Wan et al., 2009a). Meta-mafic to ultramafic rocks in the Caozhuang supracrustal rocks have Nd isotope model age of 3.7–3.5 Ga, representing the depositional age of Caozhuang supracrustal rocks (Cui et al., 2018). Wan et al. (2021) suggested that either all Caozhuang supracrustal rocks deposit at Neoarchean or they should be dismembered. There is another occurrence of fuchsite quartzites in Lulong, ca. 40 km east to Huangbaiyu. They have the similar age spectrum with those in Huangbaiyu (Chu et al., 2016). The 4.0 Ga zircon is present in the rocks, and there is a notable abundance of detrital zircons ranging from 3.99 to 3.92 Ga. The age peaks are primarily concentrated around 3.8 and 3.6–3.7 Ga. The youngest detrital zircon age recorded is 3.41 Ga. Zheng et al. (2004) identified a ca. 3.65 Ga felsic granulite xenolith within a Mesozoic volcanic rock in the Xinyang area. Zircons have negative εHf(t) values with corresponding depleted mantle model ages of 4.0–3.9 Ga, indicating that the protolith of felsic gneisses separated from the mantle prior to 4.0–3.9 Ga, subsequently remelting at 3.7–3.6 Ga, and followed by granulite-facies metamorphism at ca. 1.9