The North China Craton (NCC) is referred to as the oldest cratonic nuclei on Earth (Zhai and Santosh, 2011) and the main component of Chinese continental collage (Figure 1A) containing Eoarchean rocks as old as 3.8 Ga (Liu et al., 1992). With an area of ∼1.5 million km², the NCC is sandwiched between the southwestern Qinling-Dabie Orogen, the southern Yangtze Craton, the southeastern Sulu Orogen, and the northern Central Asian Orogenic Belt (Figure 1A). The NCC has been divided into three major tectonic units (Zhao et al., 2005): the Western Block, the Eastern Block, and the Trans-North China Orogen (TNCO) (Figure 1A). It has a complex evolutional history from the amalgamation between the Eastern and Western blocks along the Trans-North China Orogen at ∼1.85 or 1.95 Ga (Zhai and Santosh, 2011; Zhao et al., 2012), to Mesozoic-Cenozoic destruction when extensive magmatism destroyed the cratonic architecture (e.g., Xue et al., 2021). The TNCO is a nearly north-south-trending orogen across the central part of the NCC. The basement rocks comprise Neoarchean to Paleoproterozoic tonalite-trondhjemite-granodiorite (TTG) gneisses, meta-supracrustal rocks, syn-to post-tectonic granitoids, mafic dykes, and ultramafic to mafic rocks. The present study area is located in the Fuping area in the NTM, along the eastern part of the TNCO (Figure 1A).

The TM is located at the boundary between the eastern and central NCC and marks the westernmost region of the Mesozoic magmatism with a length of ∼700 km from the north to the south and a width of 50–100 km from the east to the west, connecting the southern Qinling-Dabie orogenic belt and northern Yanshan fold and thrust belt. The TM could be divided into two domains, the southern Taihang Mountains (STM) and the NTM (Figure 1B).

The major exposed strata in the area belong to the Archean basement metamorphic rocks, Proterozoic sedimentary sequences, Paleozoic sedimentary cover rocks, Mesozoic volcanic and volcaniclastic rocks, and Cenozoic sediments (Tang and Santosh, 2018). The Archean basement rocks are dominantly the Fuping Group represented by high-grade metamorphic rocks including TTG gneisses, amphibolite, marble, and magnetite-quartzite with metamorphic ages in the range of 2.5–2.7 Ga (Liu et al., 1984). These basement rocks are unconformably covered by Proterozoic sedimentary sequences. Unconformably covering the Paleoproterozoic sequences, the overlying Cambrian-Ordovician strata are dominantly composed of limestone (Dong et al., 2013). The Mesozoic strata are represented by a sequence of volcano-sedimentary rocks of andesite and andesitic breccia belonging to the Tiaojishan Formation, rhyolite, and rhyolitic breccia and tuff which have been dated as Jurassic to Cretaceous (Gao et al., 2012; Duan et al., 2016) unconformably underlying the Paleozoic sedimentary rocks. The above successions were intruded by extensive Mesozoic batholiths and stocks.

The NTM has experienced multiple tectonic activities including Archean EW trending folds, and Mesozoic NNE trending regional faults and folds. The EW axial trending Fuping anticlinorium was developed in the Archean basement rocks with the metamorphic rocks of the Fuping Group in the core and Proterozoic to Paleozoic sedimentary rocks in the limbs. Furthermore, the Mesozoic folds show characteristics of NE-NEE axial trending and wide-shaped superimposed on the earlier Fuping folds. The major controlling structures in the NTM are the Mesozoic Zijingguan and Wulonggou faults (Figure 1B). These NNE-trending regional faults cut across the Precambrian basement and Paleozoic strata, and form part of the NE–SW-trending Daxin’anling–Taihangshan gravity lineament, considered as the lithospheric boundary between the TNCO and the Eastern Block (Niu, 2005). The NEE-trending framework controls the distribution of large plutons and extrusive rocks in this area (Figure 1B).

As discussed above, the TM witnessed extensive magmatism occurred since the late Mesozoic, generating voluminous eruption of intermediate-felsic volcanic rocks, and large granitoid batholiths and plutons which are distributed in the NTM and the STM (Figure 1B). The NTM hosts plutons and stocks including the Yunwushan, Dahaituo, Sihai, Dahenan, Wanganzhen and Sigezhuang (Laiyuan magmatic complex), Chiwawu, and Mapeng plutons (Figure 1B). The intrusive rocks in the NTM are characterized by intermediate-felsic granitic rocks represented by monzogranite, syenogranite, quartz monzonite, and monzonite (Li et al., 2013; He and Santosh, 2014; Zhang et al., 2016; Yang et al., 2019a). In the NTM, the Laiyuan magmatic complex comprising the Wanganzhen and Sigezhuang plutons (Figure 1C) is the most representative intrusion which incorporates several magmatic suites consisting of voluminous granitoid plutons, sporadic extrusive volcanic lava, small ultramafic-mafic intrusive bodies, and mafic-felsic dykes. The detailed discussion about the petrology of this complex and the geochronological framework of the magmatic rocks in the NTM will be discussed in the following sections.

The volcanic rocks cover Paleozoic Cambrian-Ordovician strata. Based on petrological features, they belong to the andesite-dacite-rhyolite series (Figures 2A–C). The andesites are characterized by porphyritic texture with plagioclase, amphibole, and pyroxene occurring as phenocrysts accounting for ∼40% (Figure 3A). The matrix is characterized by a typical pilotaxitic texture with oriented plagioclase microcrystals accounting for ∼60% (Figure 3A). The dacites have plagioclase, K-feldspar, clinopyroxene, and amphibole occur as phenocrysts accounting for ∼35% (Figure 3B). The rhyolite is characterized by grey greenish color and is composed of quartz, plagioclase, biotite, and amphibole phenocrysts (Figure 3C). Plagioclase, K-feldspar, and quartz constitute the matrix with magnetite, apatite, and zircon as the accessory minerals.

The granitoids account for the major domain of the Laiyuan complex incorporating variable lithologies. In the field, the contact between different magmatic units is sometimes clear indicating they emplaced in multiple magmatic events, not crystallized from single magmatism (Figure 2D). A particular feature of the Laiyuan magmatic complex is that abundant enclaves and xenoliths (Precambrian felsic gneisses fragments) are founded in this huge granitic batholith (Figures 2E–H). The felsic and mafic dykes intruded the granitoids in some regions of the complex exhibiting a clear contact relationship with the host granitoids (Figures 2I, M).

The major rock types are syenogranite, monzogranite (porphyritic monzogranite), quartz monzonite, and monzonite (Figures 2D–H). The syenogranites are exposed along the rim of the pluton and exhibit massive structure and flesh-red color (Figure 2F). They are coarse to medium-grained and show typical granitic texture with abundant K-feldspar minerals (Figure 3D). They are composed of microcline (∼50%) or K-feldspar (∼45–50%), quartz (∼30%), plagioclase (15%–20%), and biotite (∼5%). The monzogranite occupies major domains and is exposed in the core of the intrusive complex and majorly comprises K-feldspar (∼30–35%), plagioclase (∼25–30%), quartz (∼25–35%), biotite (∼5–10%), hornblende (∼3–5%), and some accessory minerals including magnetite, sphene, and zircon. Rapakivi texture (Figure 3E) and porphyritic texture (Figure 3F) also occurred in the monzogranite rocks containing abundant mafic microgranular enclaves (MMEs). The quartz monzonites are grey-white or grey-colored, medium-grained, and display massive structure and monzonitic texture. Euhedral to subhedral plagioclase (∼25–35%), euhedral K-feldspar (∼30–35%), anhedral quartz (∼15–20%), euhedral biotite (∼10–20%), and euhedral to subhedral hornblende (∼10–20%) account for the mineral phases of the quartz monzonites. The zoning texture is common in plagioclase (0.6–2.0 mm) and K-feldspar (0.5–3.0 mm) crystals (Figures 3G, H). The monzonite and monzonite porphyry were at the northern and western rim of the pluton and are composed of plagioclase (∼35–40%), K-feldspar (∼30–35%), hornblende (∼5–15%), biotite (∼5–20%), and quartz (∼5%). The zoning texture is identified in euhedral plagioclase grains, with a size of 0.1–2.0 mm, which were sometimes included in K-feldspar grains (Figure 3I).

Abundant mafic dykes were identified in the Laiyuan area intruding the granitoids, Archean gneisses, and Paleozoic dolomites. The dykes intrude host granitoids and show sharp contact with the surrounding rocks suggesting rapid ascent of magma and fast solidification (Figures 2I, L). The lamprophyre dykes are generally fine-grained with typical lamprophyric texture of abundant mafic minerals occurring as phenocrysts (Figure 2J). The phenocryst phases are dominantly composed of euhedral to subhedral mafic minerals of amphibole, clinopyroxene, biotite (phlogopite), and minor olivine dominantly (40%–50%; by volume) which are at some places altered to carbonate, chlorite, and sericite (Figures 3J, K). The matrix is composed of pyroxene, hornblende, and plagioclase crystallites (Figure 3). The dolerite dykes are gray to light green and display massive structure (Figure 2K). They are composed of euhedral to subhedral plagioclase (∼50%), subhedral altered pyroxene (∼35%), stumpy biotite crystallite (∼10%), and altered mineral of calcite (∼10%) with accessory mineral of zircon. Besides mafic dykes, felsic dykes are also widespread in the Laiyuan complex (Figure 3L). They are exhibiting porphyritic texture with matrix and phenocryst occupying 80% and 20%, respectively (Figure 3M). The phenocrysts consist of euhedral-subhedral hornblende (∼10%), xenomorphic plagioclase with corrosion border (∼5%), xenomorphic and tabular biotite (∼5%), and quartz (∼2%). The matrix contains abundant rhombic hornblende microlites ranging from 20 to 300 μm (35%), very fine-grained feldspar (∼25%), and some other cryptocrystalline minerals (∼15%).

Except for the collected volcanic rocks, granitoids, and dyke suites, the ultramafic-mafic rocks were outcropped in some places of the complex, such as Yaogou and Longmengou which have been studied by several researches (Liu et al., 2009; Liu et al., 2010; Gao et al., 2012; Zhai et al., 2014; Hou et al., 2015; Zhang et al., 2017). At Longmengou (Figure 2N; Figure 3N, O), the ultramafic-mafic rocks consist mainly of three rock units: hornblende pyroxenite, hornblende gabbro, and gabbroic diorite (Liu et al., 2010). The pyroxenite unit shows typical cumulate textures. The Yaogou ultramafic-mafic rocks are dominated by pyroxene hornblendite and gabbronorite (Figure 2O, P; Figure 3P), and occur as isolated bodies in the rim of the Wanganzhen pluton (Figure 1C). The hornblendite bodies at Yaogou occur as variously sized enclaves or rock blocks scattered in the gabbronorite intrusion (Hou et al., 2015). These ultramafic-mafic rocks are commonly hosted in granitoids including diorite and quartz diorite.

The volcanic series of andesites and dacites are exposed in horizontal integration of contact relationships (Figure 2A) indicating they were formed by the same volcanism. In terms of volume, the granitoids occupy most of the Laiyuan complex and occur as the host rocks for ultramafic-mafic suites in the borders of the complex (Figure 1C). The mafic rocks were hosted by the granitoids in the forms of small enclaves or large stocks indicating the emplacement of granitoids was slightly later than or simultaneous with the mafic intrusions (Figure 2H). The concentrically-zoned granitoids comprise diverse magmatic units. Contact boundaries between these various intrusive suites are legible and clear (Figure 2D) which are called pulsating contact relationships indicating they were formed simultaneously. As well, the containing MMEs in the granitoids have clear contact boundaries suggesting their similar formation ages (Figures 2E, F). Furthermore, the felsic dykes intruded the granitoids and cut the MMEs (Figure 2M), and diverse mafic dykes were identified in the granitoids throughout the complex (Figure 1C). The dolerite sills were cut by the vertical lamprophyre dykes exhibiting the lamprophyre dyking event as the latest magmatism in the Laiyuan complex (Figure 2I).

Several geochronological studies have been conducted in the Laiyuan complex focusing on the ultramafic-mafic rocks (Chen et al., 2005; Zhang, 2014; Hou et al., 2015; Chang et al., 2021), intermediate-felsic granitoids (Chen et al., 2005; Chen et al., 2007; Chen et al., 2009; Qu, 2012; Zhang, 2014; Zhang et al., 2016), volcanic and sub-volcanic rocks (Gao et al., 2011; Gao et al., 2012; Gao et al., 2013; Dong et al., 2013; Song et al., 2014; Duan et al., 2016), and mafic-felsic dyke suites (Xue et al., 2019b; Chang et al., 2021). By combining available dating results yielded from this study and literature (Table 1), the temporal connection between diverse magmatic suites could be established (Figure 6A).

The ultramafic-mafic rocks are majorly exposed in Longmengou and Yaogou areas with lithology dominated by hornblendite, pyroxenite, gabbro, and gabbroic diorite occurring as isolated bodies around the complex (Liu et al., 2009; Liu et al., 2010; Zhai et al., 2014; Zhang et al., 2017). Hou et al. (2015) yielded hornblende ⁴⁰Ar-³⁹Ar ages of 154 and 133 Ma from the Yaogou hornblendite, and Chen et al. (2005), Zhang (2014) and Chang et al. (2021) dated the Longmengou gabbro and gabbroic diorite at 140–134 Ma, respectively. The field and petrographical investigations indicate that these ultramafic-mafic bodies resulted from independent magmatic events, rather than xenoliths captured by the surrounding granitoids (Zhai et al., 2014; Zhang et al., 2017). As indicated by the spatial and temporal relationships, the ultramafic-mafic rocks act as the earliest intrusive phases of the magmatic evolutional series in the Laiyuan complex ranging from Late Jurassic to Early Cretaceous (154–133 Ma).

The earliest intrusive phases were followed by Late Jurassic volcanic episodes (146–145 Ma, Figure 6A) in some places within the complex. This volcanic episode was characterized by andesitic-dacitic-rhyolitic lava eruption accounting for the typical Mujicun caldera which is composed of welded breccias, ignimbrite sheets, and lava flows (Gao et al., 2012). Within the volcanic edifice, a half ring of small sub-volcanic stocks and plugs associated with porphyry Cu-Mo deposits is found around the collapsed caldera. The emplacement of sub-volcanic suites including quartz diorite porphyry, diorite porphyry, and rhyolite porphyry took place at ∼144–140 Ma following the eruption of andesitic-dacitic magmas. In the NCC, the volcanism was intense at Late Jurassic contributing to the widespread exposures of volcanic strata referred to as the Tiaojishan Formation (Gao et al., 2012; Duan et al., 2016; Dong et al., 2018; Wu et al., 2019). Another volcanic episode which was dated in the Early Cretaceous (131–127 Ma) is also identified in this area showing a ∼15 Ma-temporal gap with earlier eruptions (Figure 6A). They were outcropped at the northern domain of the Sigezhuang pluton (Figure 1C). The Early Cretaceous volcanic rocks (ECVR) are illogical to belong to the Tiaojishan Formation whereas their lithological and geochronological features are consistent with the Zhangjiakou Formation which was majorly distributed in the central and northern margins of the NCC.

In addition to the volcanism, the Early Cretaceous witnessed the magmatic peak in the Laiyuan complex as well (Figure 6A). After the Late Jurassic volcanism and related sub-volcanic emplacement, the Early Cretaceous (∼136–126 Ma) intermediate-felsic magmatic event dominated the formation of the Laiyuan complex occurring as concentrically-zoned granitoids that constitute the most of the plutonic-volcanic complex (Figure 1C). Contact boundaries between these synchronous various intrusive suites are legible and clear (Figure 2D) which are called pulsating contact relationship indicating the compositional diversities of granitoids stem from multiple magmatic rather than simple crystallization differentiation of single magma. The MMEs contained in the granitoids were dominated by diorite and quartz monzonite and are simultaneous with the host rocks. It is noteworthy that the MMEs, ECVR, and felsic dykes which all display andesitic-dacitic lithology, were formed at the same time (∼131–127 Ma). Geochronological, petrological, and spatial connections imply their concordance in petrogenesis. They are of different forms (enclaves, dykes, and lavas) but share similar magma sources and petrogenesis.

Mafic dyking events were developed after the major parts of the complex established occurring as dolerite and lamprophyre dykes. Obtained data suggest a long-lived mafic magmatic event in the Laiyuan complex from 125 to 117 Ma generating the dolerite dyke suite (Figure 6A). In contrast to the dolerites, the lamprophyres are characterized by a limited and younger range of ages from 115 to 111 Ma (Figure 6A). Compared with the mafic intrusions, granitoids, and volcanic suites, these tiny dykes only account for insignificant proportions of the complex, however these widespread mafic dyking events throughout the complex and even intruding the country rocks suggest a common and continuous mafic dyking magmatism from 125 to 111 Ma in the NTM (Yang, 1989, 1991; Zhang et al., 2003).

The compiled and new radiometric age data, combined with field observations, define a complicated history of magmatism for the Laiyuan complex, beginning with hornblendite and pyroxenite formation at ∼154 Ma, then the first proceeding to eruptions of andesitic-dacitic-rhyolitic lavas at ∼146 Ma and emplacement of ore-related sub-volcanic rocks at ∼144 Ma, reaching the peak with the intrusion of large, concentrically-zoned granitoids from ∼136 to 126 Ma, following the second episode of volcanism at ∼130 Ma, and concluding with the tiny but widespread mafic dyking events from ∼125 to 110 Ma. To illuminate the spatio-temporal links between diverse magmatic suites is the postulate to investigate the petrogenetic relationships and the in-depth tectonic universality.

The Lu-Hf isotopic composition of zircon provides significant imprints on the magma source variations. The variations and linkages of Hf isotopic compositions are brought out through the zircon ε_Hf(t) values vs age diagram (Figure 6B). On the whole, the ε_Hf(t) values and Hf crustal model ages for the Laiyuan magmatic rocks are majorly in the ranges of -22.5 to -15.0 and 2.5 to 2.0 Ga, respectively. The negative zircon ε_Hf(t) values generally suggest that the magmas were not solely sourced from juvenile components such as juvenile crust or asthenospheric mantle, and may be primarily sourced from the enriched lithospheric mantle with or without additions from fertile mafic lower crust. This inference is also supported by previous studies of Sr-Nd isotopes and geochemical features (Figures 4G,J) for various magmatic suites from the Laiyuan complex (e.g., Chang et al., 2021). The ultramafic cumulates, mafic intrusions, intermediate-felsic granitoids, and volcanic and sub-volcanic rocks fell near the EMI field in the Sr-Nd isotope diagram (see Chang et al., 2021) suggesting they may share a common basaltic magma derived from an enriched lithospheric mantle probably previously modified due to subduction (Hawkesworth et al., 1993; Foley et al., 2000; Schmidt et al., 2009). The contribution from the enriched lithospheric mantle plays a significant role in the formation of this complex, and this is the source connection throughout different magmatic units.

Despite the similarity in their source, the complexities in the source materials are also recorded in the changes of Hf isotopic compositions (Figure 6B). It is apparent that the zircon ε_Hf(t) values display reverse variation trends at ∼130 Ma. From 150 to 130 Ma, the zircon ε_Hf(t) values are decreasing and change from variable to uniform through time, whereas these values are increasing and changing from uniform to variable from 130 to 110 Ma. The distinct variation trends probably result from the involvement of multiple materials including crustal and asthenospheric components. The Late Jurassic volcanic rocks (LJVR) which were formed at ∼146 Ma exhibit a variable zircon ε_Hf(t) values ranging from -25 to -10 (Figure 6B). Besides, inherited zircon cores from basement rocks with ages in the range of ∼2.65–2.08 Ga are common in these andesitic-dacitic rocks with positive ε_Hf(t) values (0–10) consistent with the values of basement rocks of the Fuping Complex (Figure 6B) suggesting juvenile source synchronous with the major crustal growth in the NCC (Geng et al., 2012; Zhao et al., 2012; Tang et al., 2015; Tang et al., 2016). In terms of the published Sr-Nd-Pb isotopic features, the ∼146 Ma volcanic rocks are characterized by low radiogenic Pb and high radiogenic Sr isotopic composition which might result from enriched mantle-derived melts and lower crust melts (Gao et al., 2012). Therefore, the magma source for the LJVR involved both enriched lithospheric mantle and lower crustal components. After ∼140 Ma, the intermediate-felsic magmatism which generated the granitoids, the felsic dykes and the ECVR, was intensive and culminated at ∼130 Ma. The zircon ε_Hf(t) values for the rocks during this period show a transformation to values ranging from -23.5 to -16.8 especially the ECVR (-23.5– -19.4). Considering the major lithospheric mantle source, this variation trend could be interpreted as the decreasing contribution of crustal materials to the source. As illustrated by the whole rock Sr-Nd isotopes (Chang et al., 2021), the granitoids are plotted in the field closer to the lower crustal components of the NCC than the LJVR suggesting the change of crustal materials. As a result, the decreasing input of lower crustal components accounts for the decreasing trend of zircon ε_Hf(t) values.

The mafic dyke events took place in the complex after ∼130 Ma and generated dolerites and lamprophyres showing disparate zircon Hf isotopic compositions. As illustrated in ε_Hf(t) vs age diagram (Figure 6B), the Laiyuan lamprophyres show a wider range of zircon ε_Hf(t) values from -17.2 to -3.7 compared with dolerites (-23.3 to -14.2) suggesting that the sources of lamprophyres are mixed and different from that of the dolerites whose limited negative zircon ε_Hf(t) values suggest that the dolerites were mainly sourced from an ancient enriched lithospheric mantle. The different incorporation of crustal materials into the lithospheric or asthenospheric mantles can both explain the variable and enriched zircon Hf isotope compositions in the mafic dykes. However, the detailed geochemical studies (Xue et al., 2019b) show that crustal contamination did not play a key role in the ascent of lamprophyres excluding the possibility of much incorporation of crustal materials. The increasing input of asthenospheric material through time is evident in mafic dykes, as indicated by the increasing zircon ε_Hf(t) values from dolerites to lamprophyres compared with mafic dykes from the Jiaodong area (Ma et al., 2014; Ma et al., 2016; Liu S. et al., 2017; Liu et al., 2018). The variation trend is also shown by the signature of whole Sr-Nd isotope compositions (Zhang et al., 2003). The dolerites show more depleted Nd isotopic composition (ε_Nd(t) values ranging from -15.2 to -10.5) and high initial ⁸⁷Sr/⁸⁶Sr ratios ranging from 0.70523 to 0.70683 than the lamprophyres (ε_Nd(t) ranging from -8.3 to -8.6 and initial ⁸⁷Sr/⁸⁶Sr ratios ranging from 0.7052 to 0.70554) suggesting that the lithospheric mantle source for mafic dykes and some input of asthenospheric mantle for lamprophyres in Laiyuan area as well (Chang et al., 2021). As a consequence, in terms of isotopic evidence, the increasing trend of zircon ε_Hf(t) values from dolerites to lamprophyres demonstrates the increasing involvement of asthenospheric mantle into the lithospheric mantle through time contributed to the source of mafic dykes.

In summary, the enriched lithospheric mantle accounts for the major magma source for the ultramafic-mafic rocks, intermediate-felsic granitoids, volcanic rocks and mafic dyke suites from ∼150 to 110 Ma. Over a long time, multiple sources e.g. asthenospheric materials and crustal melts, are involved in this formation process. From 150 to 130 Ma, the lower crustal contribution to the source shows a decrease from the LJVR, through granitoids, to the ECVR and felsic dykes whereas the asthenospheric mantle contribution is increasing through time from dolerites to lamprophyres during 130–110 Ma.

According to the temporal and source variations of diverse magmatic suites, the petrogenesis from different rocks could be summarized. As for granitoids, they could be classified into two groups based on their geochemical features (Xue et al., 2021) including the granitic and monzonitic rocks. The high-K calc-alkaline I-type monzogranites were generated by partial melting of the mafic lower crust while the monzonitic rocks have experienced a two-stage magmatic evolution of the first plagioclase-dominated fractional crystallization from lithospheric mantle-derived mafic magma and the second amphibole-dominated fractional crystallization to form the evolved monzonitic magma with adakitic geochemical features (Chang et al., 2021; Xue et al., 2021). Similarly, the eruptive rocks shared a similar genetic process with the monzonitic rocks thus they could also exhibit adakitic affinities (Gao et al., 2012; Xue et al., 2020). In terms of MMEs, unique petrological textures (Chen et al., 2009), the large variations of elements and Mg^# values (40–60, Xue et al., 2021), and isotopic imprints (Hf isotopes) (Chen et al., 2009) support the mixing origin of lower crust-derived felsic magma and lithospheric mantle-sourced dioritic magma for the MMEs from the Laiyuan complex. Furthermore, the underplated mantle-derived mafic magma could also experience magmatic evolution to form the gabbro and cumulative ultramafic rocks (Chang et al., 2021). In conclusion, intense mantle and crustal magmatic processes have been identified in the formation of the Laiyuan magmatic complex. Above detailed petrological, geochemical, isotopic, and geochronological research have illustrated that the incorporation of the thickened lower crust and enriched lithospheric mantle in the source, and the involvement of diverse magmatic processes, have played a significant role in the petrogenesis of the Laiyuan igneous complex arousing the heterogeneities.

Above detailed petrological, geochemical, isotopic, and geochronological research have illustrated that the incorporation of the thickened lower crust and enriched lithospheric mantle in the source, and the involvement of diverse magmatic processes including the partial melting of variable sources, fractional crystallization, magma mixing and mingling, and crystal accumulation and compaction, have played a significant role in the petrogenesis of the Laiyuan igneous complex. It could be attributed to the crust-mantle interaction contributing to the formation of the Laiyuan magmatic complex (Figure 7A). The mantle-derived underplated mafic magmas act as not only the thermal source to induce the crustal melting, but also the mafic end-member to interact with the felsic melts/magmas derived from the crust. As a result, a series of magmatic rocks with compositional heterogeneity were formed, including mafic-ultramafic rocks and felsic rocks in the forms of eruption, plutonic emplacement, enclave, and felsic dyke (Figure 7A). In the central NCC, such magmatic complexes (plutons) similar to the Laiyuan complex, such as the Dahenan complex (Chen et al., 2009) and Mapeng pluton (He and Santosh, 2014) from the NTM, and the Fushan pluton (Li et al., 2019) from the STM, are widespread indicating that the intense crust-mantle interaction is the common deep process beneath the intra-domain of the NCC. The crust-mantle interaction took place during Late Mesozoic, peaking at the Early Cretaceous, consistent with the NCC destruction peaking period (Zhang et al., 2014; Liu et al., 2019; Wu et al., 2019) revealing the tight internal genetic relationship between the magmatism, interaction, and destruction. In brief, the deep crust-mantle interaction holds important clues to the Mesozoic tectonic setting and craton destruction mechanism in the central NCC. Complex source materials and multiple magmatic evolutional processes contributed to the compositional diversity of the Laiyuan complex (Figure 7A).

The above source discussion has demonstrated the input of the asthenospheric mantle is increasing from dolerite dykes (126–117 Ma) to lamprophyre dykes (115–111 Ma) indicating the magma sources for mafic dykes have changed from the enriched lithospheric mantle to the enriched lithospheric mantle+asthenospheric mantle (Xue et al., 2019b). In addition, the Dy/Yb ratios are useful to evaluate the source nature and degree of partial melting of mafic dykes (Ma et al., 2016). From dolerite to lamprophyre, the Dy/Yb ratios are decreasing from 2.66–3.21 to 2.45 to 2.65 (Xue et al., 2019b) suggesting the melting depths have shifted from 80 to 100 km (Garnet stability field) to ∼80 km (Garnet-spinel transitional field), and the degrees of partial melting of the lithospheric mantle are increasing from 3%–8% to 8%–14% (Duggen et al., 2005; Mckenzie and O'Nions, 1991; Robinson and Wood, 1998; Yang et al., 2010). All these variations could be interpreted by the lithosphere thinning and the asthenosphere upwelling with the fact that the asthenosphere cannot melt until the thickness of the lithosphere has been reduced to less than about 80 km. Furthermore, by comparing with isotopic (e.g., ε_Hf(t) values, Figure 6B) and geochemical features (e.g., TiO₂ contents and Nb/La ratios, not shown) of asthenospheric mantle-derived and lithospheric mantle-derived mafic dykes from Jiaodong areas (Ma et al., 2014; Ma et al., 2016; Xue et al., 2019b), the Laiyuan mafic dykes show special “transitional” features indicating the lithosphere-asthenosphere interaction could be interpreted as the possible petrogenesis for mafic dykes in the central NCC (Figure 7B). In this case, the lithosphere-asthenosphere interaction means the partial melting of the asthenospheric mantle interacted with the eroded lithospheric mantle material to produce the lamprophyre dykes in the Laiyuan complex similar to the Datong Cenozoic basalts from Datong Volcanic Field near Laiyuan area (Xu et al., 2005). In addition, the lithosphere-asthenosphere interaction exhibits smooth and gradual characteristics which are distinct from the intense and rapid mafic diking events in Jiaodong area during the Mesozoic indicating the different lithospheric evolutions (Ma et al., 2014).

In the eastern and central NCC, three metallogenic pulses are identified, i.e. 200-160 Ma, ca. 140 Ma, and 130–110 Ma when the tectonic regime was under post-collisional setting, transforming from compression to extension, and intense extensional setting, respectively (Mao et al., 2005). The significant tectonic regime transformation from Late Jurassic to Early Cretaceous was also recorded by the widespread metamorphic core complex in the NCC (Wang et al., 2012) (Figure 8A). Detailed geochronological studies of the Yunmengshan metamorphic core complex illustrate a rapid change in the tectonic setting from NNE-SSW compression to NW-SE extension in the earliest Cretaceous (Zhu et al., 2015). In the study area, geochronological studies on the Mujicun deposit show that the volcanic rocks, porphyry intrusion, and porphyry-type and skarn-type of mineralization were formed during the same event at 145–140 Ma consistent with the important tectonic regime changing period (Gao et al., 2012; Gao et al., 2013; Dong et al., 2013; Hou et al., 2015) similar to the skarn-porphyry Cu-Mo and Mo-W mineralizations in Jiaodong area (Goldfarb and Santosh, 2014) and East Qinling orogen (Li et al., 2018; Yang et al., 2019b). Furthermore, the LJVR belongs to the Tiaojishan Formation which was also regarded as the intra-plate volcanism induced by the transition in the tectonic regime (Dong et al., 2018). Therefore, the early formation of the Laiyuan complex was associated with the tectonic regime transition from compression to extension accompanied by the formation of LJVR, sub-volcanic rocks, and hosted Cu-Mo mineralization.

Lithospheric extension beneath eastern China during the Early Cretaceous is supported by several lines of evidence, including a series of fault basins, numerous detachment faults, metamorphic core complexes, and associated voluminous magmatism (Zhu et al., 2011) (Figure 8A). Compared with the Jurassic magmatism, the Early Cretaceous magmatism was more intense and widespread throughout the eastern and central NCC marking the peak of the extension (Figures 8A, B). Apparently, the Early Cretaceous intense magmatism in the study area displays a close relationship with the extensional setting because the lithosphere-asthenosphere and crust-mantle interaction to generate the Laiyuan magmatic complex are commonly marking deep extension architecture (Campos et al., 2012; Orozco-Garza et al., 2013; Li et al., 2014; Deng et al., 2017). To interpret the trigger of the extensional tectonic regime, several mechanisms have been presented. Among the two popular models, one relates the Triassic collision between the NCC and Yangtze Block with the intra-continental extensional regime during the post-collision (Zhang et al., 2002). The other model proposes the nearly W-E subduction of the Paleo-Pacific Ocean which changed the geodynamic regime from N-S transpressional setting to nearly W-E extensional setting (Li and Santosh, 2017). A marked age polarity has been identified in the East Asian magmatic suites with a northwestward younging trend from Japanese islands (∼210 Ma), through the Jiaodong and Liaodong areas (180 Ma), to the Taihang Mountain in central NCC (138 Ma), which has been linked with the subduction process of Paleo-Pacific Plate (Chen et al., 2005), with extension of the NCC triggered by the subduction process.

Before discussing the possible mechanism for the NCC destruction, the prior focus is the tectonic triggering forces for the destruction. Previous studies show that the subduction of the oceanic plate and plume erosion act as the major driving force for craton destruction in the margins or within continental interiors, respectively (Wilde et al., 2003; Menzies et al., 2007). As shown in the tectonic setting discriminative diagrams (Figure 9), the rocks from the Laiyuan complex are showing subduction-related characteristics. As well, the rocks exhibit geochemical features similar to the rocks generated in active continental margins (Figure 9). However, these rocks were formed far from any active continental margin arc setting during the Mesozoic and show an intra-plate setting as also suggested in previous studies from the TM and north Hebei Province (Gao et al., 2011; He et al., 2017; Dong et al., 2018; Li et al., 2019; Yang et al., 2020). The arc-like characteristics might be an inheritance from the lithosphere beneath the central NCC which was influenced by the oceanic plate subduction through far-field effects (He et al., 2017). As well, the granitoids plotted in the VAG field (Figure 9A), and the mafic rocks fell in the field of active continental margin (Figures 9B, C) indicating the primary controlling effect exerted by subduction to form the magmatic rocks in the central NCC. The following lines of evidence support that the NCC destruction was triggered by the subduction of the Paleo-Pacific Plate, neither by the subduction of the Paleo-Asian oceanic plate to the north nor the subduction of the Paleo-Tethys and following the continental collision between the NCC and Yangtze Craton to the south (Windley et al., 2010). Firstly, the NCC experienced extensive destruction in its eastern and central parts showing a gradual thinning trend from west to east whereas the western part still has a thick and stable lithosphere suggesting the subduction effect came from the east (Chen, 2010). Secondly, combined age data of Mesozoic magmatic rocks from the NCC (Figure 8C) show that the Jurassic calc-alkali magmatism exhibits a westward younging trend, whereas the Cretaceous calc-alkali magmatism shows a reverse eastward younging trend, indicating the role of subduction and rollback of the Paleo-Pacific Plate in the spatial-temporal migration of Mesozoic magmatism in the NCC (Wu et al., 2019). Thirdly, there are northeast-extending belts of the Mesozoic magmatic rocks and contemporaneous sedimentary basins distributed parallel to the subduction zone of the Paleo-Pacific Plate (Li et al., 2012; Wang et al., 2012) (Figure 8A). Therefore, the subduction of the Paleo-Pacific Plate exerted a principle influence on the thinning, extension, and destruction of the NCC.

Based on previous studies and this study, some key stages associated with the subduction of the Paleo-Pacific Plate can be recognized: initiation of the subduction beneath Northeast China between ∼200–190, low-angle flat subduction between ∼170 and 145 Ma, the sinking or rollback between ∼145–110, stagnancy and vanish of Paleo-Pacific slab in the mantle transition zone at ∼110–50 Ma (Liu et al., 2019; Wu et al., 2019; Zhu and Xu, 2019). During Late Jurassic, at ca. 155 Ma, the Paleo-Pacific Plate began to roll back, with the tectonic setting changing from compression to extension. By ∼145 Ma, the slab had mostly rolled back contributing to unstable mantle flows and upwelling of the asthenosphere. In summary, the westward subduction, retreat, rollback and stagnation of the Paleo-Pacific Plate are the deep driving force of the NCC destruction resulting in the heterogeneous lithosphere and various evolutional processes in the deep beneath the NCC, furthermore manifested as distinct magmatic rocks series in the shallow.

Seismic data indicate that the present lithospheric thickness of the NCC becomes gradually reduced from the Western Block (∼200 km in the Ordos basin) through the central region (120 km in the TM) to the Eastern Block (only 70 km in the Bohai Bay region) (Chen, 2010). The geophysical data also reveals the crustal structure is varying from the eastern to the central NCC, with the thickness of the lower crust decreasing from ∼20 km in the TM to only 6 km in the Bohai Bay (Zheng et al., 2007). In addition, by studying the Cenozoic basalts and hosted xenoliths, the ancient lithosphere in the eastern NCC has been replaced by juvenile lithosphere while just a small portion of the lithosphere ancient has changed to juvenile materials and the ancient lithosphere still dominated (Liu et al., 2019; Wu et al., 2019) (Figure 8D). These differences in thickness and structure essentially reflect the spatial variation of lithospheric evolution throughout the NCC.

The magmatic similarities in both central and eastern NCC reveal the consistency of lithospheric evolution by the Late Jurassic. However, distinct from Jurassic magmatism, the Early Cretaceous magmatism occurred more widely, resulted in extremely variable rock types and chemical compositions, and involved multiple crustal and mantle sources (Zheng et al., 2018; Wu et al., 2019). The crust-mantle interaction played a significant role during their formation in both central and eastern NCC, but may be of different forms. As discussed in this study, the underplated basaltic magma derived from the enriched lithospheric mantle interacted with the thickened lower crust to account for the variable magmatic rocks in the central NCC (bottom to up), whereas the melts derived from the delaminated lower crust interacted with the overlying mantle peridotite contributed to the formations of high-Mg andesites and adakites in the eastern NCC (up to bottom) (Gao et al., 2004; Jiang et al., 2007; Gao et al., 2009; Xu et al., 2013). The different forms of crust-mantle interaction are consistent with the thickness variations of the lithosphere.

Notably, the mafic dyke events that occurred in both regions offered direct evidence to identify the distinct lithospheric evolution. Two types of lamprophyres with the same emplacement ages of ca. 121 Ma have been discovered in the Jiaojia gold deposit from the Jiaodong region (Ma et al., 2014; Deng et al., 2017): one is the high-Ti lamprophyres sourced from the partial melting of an asthenospheric mantle with juvenile and depleted isotopic characteristics (ε_Hf(t) values ranging from -4.7 to 2.1), another is the low-Ti lamprophyres sourced from the lithospheric mantle with ancient and enriched isotopic features (ε_Hf(t) values ranging from -29.3 to -23.1) (Figure 6B). The co-occurrence of the two types of lamprophyres records a rapid transition from lithospheric to asthenospheric mantle sources, indicating the rapid detachment of the lithosphere and rapid upwelling of the asthenosphere beneath the eastern NCC (Ma et al., 2016; Deng et al., 2017). However, as revealed by the increasing input of asthenospheric materials through time for the source of lamprophyres from 115 to 111 Ma, and the relatively uniform enriched lithospheric mantle source for the dolerites from 125 to 117 Ma, a progressive and slow lithospheric thinning and asthenospheric upwelling process occurred at the central NCC. The distinct lithospheric evolutional processes in the central and eastern NCC may result from the different destruction mechanisms and lead to the different lithospheric evolution beneath the central and eastern NCC at present.

Several models were proposed to interpret the destruction process including convective destabilization (Houseman et al., 1981; Morency et al., 2002), tectonic erosion (Maruyama et al., 2007; Santosh, 2010), destabilization due to the Indo-Eurasian collision (Menzies et al., 2007), thermo-mechanical erosion (Griffin et al., 1998; Xu, 2001), and continental delamination (Gao et al., 2004; Windley et al., 2010). Among these models, thermo-mechanical erosion and lithospheric delamination modes are the more accepted mechanisms to explain the lithospheric thinning process. These two models have contrasting characteristics of magmatic imprints. In the case of thermo-mechanical erosion, the upwelling asthenosphere gradually heats up, weakens, and erodes the lowermost lithosphere (Xu et al., 2005; Xu et al., 2009). Progressive removal would contribute to considerable thinning of the lithosphere (Ma et al., 2016). The magmatism related to this process will have lithospheric mantle features at the beginning, followed by asthenospheric mantle characteristics with progressive thinning (Xu et al., 2009; Cai et al., 2013). The formation of the Laiyuan magmatic complex perfectly fits such characteristics. At early stage, the lithospheric mantle-derived magmas underplated the crust to generate the mafic rocks, andesitic volcanic rocks, and granitoids. Gradually, the clues of the asthenospheric mantle are increasing in the dolerites and lamprophyres. The smooth and progressive transition process indicates the case of thermo-mechanical erosion in the central NCC. In contrast, the delamination model hypothesizes that thickened lower crust and the coupled lithosphere sunk into the convective asthenospheric mantle to produce simultaneous lithospheric and asthenospheric mantle-derived magmas as well as mixed felsic magmas (Gao et al., 2004; Wu et al., 2008). The two types of mafic dykes in the Jiaodong area (Ma et al., 2014; Deng et al., 2017), and the formation of high-Mg adakitic rocks and mafic dykes from different sources in the proximal western Shandong region (Liu S. et al., 2017; Li et al., 2017) indicate the delamination of lithosphere can be well demonstrated in the eastern NCC. Furthermore, given the different lithospheric nature (Figure 8D), it is difficult to use the delamination model to interpret the formation of Mesozoic magmatic rocks in the central NCC whereas it is reasonable to apply the thermal-mechanical erosion to account for the craton destruction in the central NCC. The lithosphere-asthenosphere and crust-mantle interactions constitute the vertical craton destruction phenomenon induced by thermal-mechanical erosion. The delaminated lower crust cannot pass through the thick lithospheric mantle to founder into the asthenosphere because of the buoyancy and strength in the central NCC.

In summary, it could be concluded that the thermal-mechanical erosion happened in the Central NCC, and lithospheric delamination took place in the eastern NCC. The lithosphere experienced different evolutional processes in the NCC. In the central NCC, gradual erosion and replacement of ancient lithosphere happened to lead to most of the ancient lithosphere has been preserved. However, in the eastern NCC, the ancient lithosphere was rapidly delaminated and was totally replaced by the juvenile lithosphere. Both two mechanisms played a significant role in the NCC destruction process to form variable magmatic rocks. Although the two mechanisms certainly differ from each other, the connection between them cannot be eliminated. The rapid and intense lithospheric delamination would trigger thermo-mechanical erosion within the interior domains of the NCC, and the slow and gradual erosion would act as the preclusion of large-scale delamination.

Combining the spatial, temporal, genetic, and tectonic linkages, considering the state change of the Paleo-Pacific slab beneath the NCC, an integrated petrogenetic model has been proposed to describe the magmatic evolution of the Laiyuan magmatic complex (Figure 10). Both the two mechanisms combined with the Paleo-Pacific slab played a significant role in the NCC destruction process to form variable magmatic rocks.

During Early Jurassic (∼200 Ma), the initiation of subduction of the Paleo-Pacific Plate occurred beneath Northeast Asia (Ma and Xu, 2021). Until ∼150 Ma, the slab has reached the position beneath the central NCC. The cold slab lowered the geothermal gradient of the mantle beneath the craton and depressed direct mantle melting. During this period, the central NCC was under compression which thickened the lithosphere in the central NCC. The LJVR with the sub-volcanic suites corresponding to Tiaojishan Formation were formed during this period whose petrogenesis could be attributed to the MASH process (melting, assimilation, storage, homogenization) highlighting the important role of partial melting of the thickened lower crust (Hildreth and Moorbath, 1988; Gao et al., 2012). The deep hornblende-dominated fractional crystallization process accounts for the sporadic ultramafic cumulates and evolved andesitic magmas with adakitic affinities which ascend through the crust to erupt.

During 145–140 Ma, fast slab rollback occurred leading to hot asthenosphere upwelling and extensional setting in the central NCC. This intense mantle convection transformed from central to eastern NCC identified by the eastward younging trend of magmatism after ∼140 Ma (Figure 8C). Induced by the upwelling of hot asthenosphere, the pre-weakened metasomatized lithospheric mantle would be heated and eroded, which would lead to partial melting, producing the parental basaltic magma. These magmas would be underplated beneath the base of the thickened lower crust, acting as not only the thermal source to induce the crustal melting, but also the mafic end-member to interact with the felsic melts/magmas derived from the crust. The intense and consistent crust-mantle interaction accounts for the petrogenesis for the formation of the Laiyuan magmatic complex, including granitoids (136–126 Ma), MMEs (129–126 Ma), ECVR (131–127 Ma), and felsic dykes (131–127 Ma). The compositional heterogeneities of the igneous complex resulted from the multiple involved mantle and crustal sources, chaotic mixing and mingling process, and the complicated fractional crystallization during the deep interaction process.

From 145 to 110 Ma, the lithosphere in the central NCC underwent continued thinning and erosion. Through time, the lithosphere became substantially thin, and lithospheric mantle-derived magmas could migrate through the lithospheric faults and intrude the plutons or country rocks leading to the formation of dolerite dykes at 125–117 Ma. The continuous asthenospheric upwelling caused heterogeneous erosion along weak zones resulting in non-uniform destruction of the lithosphere. In the eastern NCC, at ∼120 Ma, delamination of the eclogitic lower crust occurred and the evacuated mantle was replaced by hot asthenosphere. However, in the central NCC, the delamination didn’t happen but the thermal-mechanical erosion took place to generate eroded lithosphere. Following delamination in the Jiaodong area at ∼120 Ma, and the rapid slab rollback induced intense mantle convection, with further input from the accumulating slab graveyards in the mantle transition zone, the mantle upwelling and thermo-mechanical erosion reached their peak. The continuous lithospheric thinning eventually resulted in the upwelling asthenosphere reaching the depth where it could melt (80 km). More asthenosphere mantle began to melt with eroded lithospheric mantle. The partial melting of the asthenospheric mantle and its interaction with the lithospheric mantle material produced the lamprophyre with both arc-type and OIB-type characteristics dykes from ∼115 Ma to 111 Ma.

Thus, the above discussion interprets the integrated formation process of the Laiyuan magmatic complex. This formation mechanism could be also used to account for the petrogenesis of the magmatic plutons in the central. It is favored that both of the lithospheric delamination and thermo-mechanical erosion together played a key role in the destruction of the cratonic architecture of the NCC (Figure 10).