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Purposes The Hutuo Group belongs to the Early Proterozoic strata. As one of the most typical Paleoproterozoic strata in North China, the timing redefinition of the Hutuo Group is of great significance to the establishment of the early Precambrian stratigraphic chronology framework, the discussion of the early Precambrian geological evolution process in North China and the study of plate assembly. Methods This article conducts a detailed study of the Dongye Subgroup strata of the Hutuo Group, collecting 24 detrital zircon samples from the Jian'ancun Formation of the Hutuo Group. From 23 similar age detrital zircons, we define the weighted average age of the bottom boundary of the Hutuo Group is 2 469 Ma, and regional tectonic movements occurred in the Wutai area around 1 855 Ma. According to the 1 109 zircon ages in Hutuo Group from previous studies, we considered that the ages of >2.5 Ga are from underlying Gaofan subgroup and the maximum depositional age of Hutuo Group was early Paleoproterozoic. Findings The results show that the crust of the Wutai area was unstable at 2 376, 2 170, 2 066, 1 988, and 1 825 Ma, resulting in multiple magmatic events. The 1 825 Ma zircon age can further indicate the occurrence of the Lyuliang movement, and provide a basis for the early Proterozoic North China Craton integration.

The Hamersley Group in the Hamersley Basin, Western Australia, contains major deposits of banded iron formation of Neoarchean–Paleoproterozoic age (2629–2449 Ma). The 2450 Ma Weeli Wolli Formation near the top of the group includes banded iron formation with microbands (≤0.05–0.5 mm to rarely 1 mm thick) of chert and iron oxide lamina couplets that display distinctive cycles. Some adjacent, thin microbands have merged with compaction and the diagenetic removal of chert laminae, and maximum counts of cycle period by different studies is preferred, suggesting a period of ∼28 ± 2 microbands. Associated cyclic iron formation shows soft-sediment plastic deformation and brittle fracturing. Rare earth element geochemistry indicates that much of the iron in late Archean–early Paleoproterozoic banded iron formations was derived from submarine hydrothermal systems. Monitoring of hydrothermal vents on mid-ocean ridges and seamounts has identified tidal modulation of the discharge, temperature and dispersal of deep-sea hydrothermal plumes principally by semidiurnal variations in tidal loading and earth tides. Microearthquake swarms are associated with deep-sea hydrothermal systems at the crests of mid-ocean ridges, and tidal triggering of microearthquake activity is indicated for a hydrothermal system on the East Pacific Rise. The microband cycles in the Weeli Wolli Formation are interpreted as tidalites, comprising ∼28 ± 2 semidiurnal microbands per lunar (synodic) fortnightly cycle, related to the tidally modulated activity of a submarine hydrothermal system. The associated plastically deformed and brittle-fractured sediments are viewed as seismites resulting from microearthquakes also related to the hydrothermal system. The Weeli Wolli microband cycles and seismites may represent a rarely identified instance of iron-formation deposition near a submarine hydrothermal system. Submarine hydrothermal venting was a major source of iron in late Archean–early Paleoproterozoic banded iron formations. Semidiurnal variations in tidal loading and earth tides commonly modulate present-day deep-sea hydrothermal activity, and microearthquake swarms are associated with deep-sea hydrothermal systems. Early Paleoproterozoic banded iron formation from the Hamersley Basin displays cycles with an estimated period of ∼28 ± 2 microbands and associated plastic deformation and brittle fracturing. The microband cycles are interpreted as tidalites comprising ∼28 ± 2 semidiurnal increments grouped in fortnightly cycles at a tidally modulated submarine hydrothermal system, and the deformed sediments as seismites caused by related microearthquake activity. [ABSTRACT FROM AUTHOR]

Reworking or growth of the Hadean (>4.0 Ga) continental crust provides important hints in understanding the early evolution history of Earth. In this study, a comprehensive program of zircon U-Pb dating and Hf isotope analyses, as well as whole-rock major and trace element analyses, has been carried out on the Muzidian granitic gneisses from the northern Dabie orogen. The Muzidian gneisses are tonalite or granodiorite in composition, and have geochemical features resembling those typical of the tonalite-trondhjemite-granodiorite (TTG) suites. Zircon U-Pb dates range from ~2.5–2.4 Ga in the magmatic cores and from ~2.1–2.0 Ga in the metamorphic rims. Both the zircon cores and the rims have highly negative ɛ Hf (t) values of −25.2 to −19.9 and −31.0 to −28.1, respectively, corresponding to T crust of 4.25 Ga to 3.98 Ga, thereby, indicating that the protoliths of the orthogneisses in the northern Dabie orogen were formed by reworking of Hadean continental crust. This provides strong evidence for the presence of Hadean continental crust in the northern Yangtze block. These remnants of Hadean rocks resided in the continental crust of the Yangtze block for more than about 1700 Ma before being reworked. Compared to the ancient crustal components in the Kongling area of the Yangtze block, the Muzidian area along the northern margin of the Yangtze block seems to be more prospective for further occurrences of the Hadean zircon and/or rocks. Unlabelled Image • The Muzidian TTG gneisses from the northern Dabie orogen are dated at 2.5-2.4 Ga, and underwent 2.1-2.0 Ga metamorphism. • The TTG gneisses were derived from reworking of potentially Hadean continental crust. • Hadean (>4.2 Ga) crustal components may potentially exist in the northern Dabie orogen. • There is more likelihood of finding Hadean crustal remnants in the northern Yangtze block than in the Kongling area. [ABSTRACT FROM AUTHOR]

Recent geological survey has identified the Early Paleoproterozoic meta-mafic intrusions in the southwestern Yangtze Block. We present geochronological, whole-rock geochemical and Nd isotopic data for these meta-mafic rocks to better address the tectonic evolution of the Yangtze Block during the Early Paleoproterozoic Period. Geochronological data show that the meta-mafic rocks have zircon ages of 2 395-2 316 Ma. They have high TiO2 contents of 1.40 wt.%3.66 wt.% and Nb concentrations of 13.7 ppm45.5 ppm, thus aregrouped as Nb-enriched mafic rocks. These mafic rocks are characterized by tholeiitic compositions with enrichment of LREEs and LILEs, and can be divided into two groups. Group 1 samples display E-MORB-like geochemical characteristics. Group 2 samples have positive εNd(t) values of 4.0–5.0. Geochemical data indicate that all meta-mafic rocks were likely derived from a depleted asthenospheric mantle. REE modeling indicates lower degree of partial melting for Group 2 samples (3%–10%) relative to Group 1 samples (15%–20%). Taking into account contemporaneous post-collisional granitoids in southwestern Yangtze Block, we propose that these meta-mafic rocks were formed in a post-collisional extension setting. These meta-mafic rocks can be compared with those in Africa, South America and Europe, and might be linked with the Arrowsmith orogenic belt. KEY WORDS: zircon dating, geochemistry, Early Paleoproterozoic, Nb-enriched rocks, Yangtze Block. [ABSTRACT FROM AUTHOR]

Magmatic rocks in the North China Craton (NCC) are crucial to unraveling the tectonic background during the tectono-magmatic lull (TML, 2.45–2.20 Ga) and to constraining the initiation of plate tectonics. In this study, previously published zircon U–Pb–Hf–O data and whole-rock geochemistry are collected from the early Paleoproterozoic felsic intrusive rocks in the southern Trans-North China Orogen (TNCO) and new data presented. The formation ages and petrogenesis of the early Paleoproterozoic felsic intrusive rocks in the southern TNCO are summarized to constrain the tectonic setting during the TML. Zircon U-Pb geochronology of the tonalite–trondhjemite–granodiorite (TTG) gneisses yielded intrusive ages of ∼2.3 Ga and ∼2.2 Ga. Geochemically, the gneisses can be classified as ∼2.3 Ga high-Al and ∼2.2 Ga low-Al types, and were likely derived from the partial melting of pre-existing lower crust at medium and low pressure, respectively. The heavy rare earth depletion and have high Sr/Y and La/Yb values of the ∼2.3 Ga TTG gneisses indicates that they were derived from the partial melting of thickening lower crust in the garnet-hornblende phase, which is consistent with a gradual thickening of the crust. The potassic granitoids are geochemically divided into I-type and A-type granites and have early Paleoproterozoic ages at ∼2.3 Ga and ∼2.27 Ga. Zircon U-Pb geochronology of the dioritic gneisses yielded intrusive ages of ∼2.3 Ga. These potassic granitoids and dioritic gneisses were generated by the partial melting of ancient basement rocks, with variable degrees of juvenile contributions. Considering the large variety of zircon ε Hf (t) values, and Sr/Y and (La/Yb) N ratios obtained for the early Paleoproterozoic felsic intrusive rocks, the crustal thickening that occurred via tectonic compression prior to ∼2.3 Ga is most likely due to convergence. The high δ18O and low δ18O values in the southern TNCO may have been the result of slab subduction, which can effectively transfer surface material directly or indirectly to the lower crust, and the TTGs that formed as a result of the subsequent partial melting inherited the high δ18O characteristics to varying degrees. Glacial meltwater is an important source of low δ18O fluids and a large number of rift events developed during the 2.5–2.4 Ga interval. The resulting fractured environment provided sufficient space for the infiltration of surface water, and rocks with low δ18O characteristics are likely produced by the remelting of crustal rocks that have been thermally altered by surface water or atmospheric hydrothermal processes. Combined with evidence such as the Paleoproterozoic Alaska-type intrusive rocks, diabases, sanukitoids and sedimentary rocks, the TNCO is proposed to have been in a subduction compression setting at ∼2.3 Ga. Meanwhile, the alkaline and related elements (such as Rb, Th, Ba and Nb), K 2 O/Na 2 O ratios, and zircon δ18O values of the magmatic rocks increased significantly during the TML, which indicate that plate subduction started prior to ∼2.3 Ga. The difference in the intensity of the magmatism during the TML may be related to continental freeboards in different regions– [ABSTRACT FROM AUTHOR]

Highlights • Early Paleoproterozoic magmatism were reported in Phan Si Pan Complex in North Vietnam of the Yangtze Block. • The ca. 2.3 Ga quartz monzonite formed at a collision-related crustal thickening event. • The ca. 2.1 Ga A-type gneissic granite formed within an extensional tectonic setting. • The Phan Si Pan Complex was an independent terrane separated from other parts of the Yangtze Block during the early Paleoproterozoic. • The Yangtze Block was linked to northwestern Laurentia in the Pre-Nuna supercontinent. Abstract Our understanding of the early evolution of the Yangtze Block is limited by the sparsely dispersed nature of pre-Neoproterozoic exposures. New, integrated petrographic, zircon U-Pb age and Hf-Nd isotope analyses, and whole-rock geochemical data for early Paleoproterozoic granites in the Phan Si Pan Complex provides new insights into the evolution of the Yangtze Block as well as its role in the Pre-Nuna supercontinent. LA-ICP-MS zircon U-Pb dating of magmatic zircons from quartz monzonite and gneissic granite yielded 207Pb/206Pb ages of 2306 ± 12 Ma and 2096 ± 15 Ma, respectively. Zircons from the quartz monzonite have ε Hf(t) values ranging from −4.1 to −2.1, corresponding to T DM2 model ages of 3002–2890 Ma, whereas zircons in the gneissic granite have ε Hf(t) values between −0.95 and +1.72 and corresponding T DM2 model ages of 2660–2516 Ma, which are consistent with their whole-rock Nd isotope values. Geochemically, the quartz monzonites are I-type granites. Combined with their relatively high Sr/Y ratios and low Y concentrations, as well as fractionated REE patterns with relatively high LREE but low HREE concentrations, they were probably generated by partial melting of the thickened middle-lower crust under elevated temperature. Geochemical and isotopic signatures suggest that the ca. 2.1 Ga gneissic granites are high-K calc-alkaline, ferroan A-type granites formed by partial melting of juvenile crustal source at high temperature and low pressure with little involvement of ancient crustal material. The Phan Si Pan complex has a distinct early Paleoproterozoic crustal evolution history compared with the other crustal provinces of the Yangtze Block, suggesting independent histories that were not unified until the late Paleoproterozoic during the assembly of Nuna. Moreover, the magmatism and tectonic evolution of the north Vietnam region is broadly similar to that of the Arrowsmith Orogen of the Rae craton in Laurentia suggesting a potential spatial linkage. The geologic record of the Yangtze Block does not support an early Paleoproterozoic shutdown of plate tectonics. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • 2.4 Ga granitoids of the Quanji Massif show high-K I-type and A 2 -type affinities. • The magmas were derived from early Paleoproterozoic juvenile crust and ancient crust. • The plate tectonics did not shut down during the early Paleoproterozoic. Abstract The global plate tectonic regime in the early Paleoproterozoic period is highly debated. Granitoids bear key information to address such a debate. Petrological, geochemical and geochronological studies are conducted on two post-collisional granitoid plutons in the Quanji Massif, northwestern China, to investigate the tectonic regime during this period. The granitoids are composed of syenogranite, monzogranite, and granodiorite, with minor tonalite, which intruded into the Delingha and Hudesheng regions at ca. 2.39–2.37 Ga. These plutons are high-K I-type granitoids with variable Ga/Al ratios, showing some characteristics of A 2 -type granitoids. They are characterized by enrichment of LILEs and LREEs and depletion of Sr, P, Ti, and Eu. They show depleted Nd and Hf isotope signatures with whole rock ε Nd (t) = +0.7 to +4.8 and zircon ε Hf (t) = −1.0 to +7.8, indicating a juvenile crustal growth event at ca. 2.44–2.37 Ga. Our new results together with other coeval post-collisional granitoids in the Quanji Massif suggest that the protracted post-collisional magmatism at ca. 2.39–2.34 Ga occurred just after a short interval of subduction and generation of juvenile magmas before or around ca. 2.4 Ga. Collectively, the formation of these ca. 2.4–2.3 Ga granitoids in the Quanji Massif may correlate with coeval granitoids in the Tarim and North China cratons, and is broadly coeval with magmatism in several other cratons in the West African and Canadian Shields. Thus, the globally well-documented magmatism at early Paleoproterozoic, or Siderian, provides further information for filling up the age gap of the so-called plate tectonic "shutdown" in the early Paleoproterozoic period worldwide. The geologic record therefore suggests no Siderian shutdown of plate tectonics, but instead, continuous global subduction and generation of juvenile magmas from the Archean through the Paleoproterozoic. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • We present the rarely reported early Paleoproterozoic magmatic records in the Yangtze Block. • The ca. 2.36 Ga Cuoke monzogranites formed within post-collisional setting. • They were likely derived from a source comprising mainly Mesoarchean crustal materials. • The SW Yangtze Block likely underwent a collision event related to the Arrowsmith orogeny. • A spatial connection between Yangtze and Laurentia in the Columbia supercontinent is favored. Abstract The early Paleoproterozoic is an essential period for understanding the early tectonic evolution of the Yangtze Block and its reconstruction in the Columbia supercontinent, whereas these issues are largely unknown due to the scarce preservation of early Paleoproterozoic geological records. This study presents rarely reported early Paleoproterozoic granitoids from the southwestern Yangtze Block, with integrated studies of zircon U-Pb ages, Lu-Hf isotopic compositions and whole-rock geochemistry. Magmatic zircon U-Pb dating for two monzogranite samples yields weighted mean 207Pb/206Pb ages of 2359 ± 16 Ma and 2363 ± 16 Ma, providing unambiguous evidence for the presence of early Paleoproterozoic magmatism in the Yangtze Block. All the samples have high A/CNK values of 1.30–1.61, typical of S-type granite. These rocks have low total REE contents of 72.5–139.0 ppm with marked enrichment in LREEs ((La/Yb) N = 10.73–23.83) and conspicuously negative Eu anomalies (Eu/Eu* = 0.46–0.55). The rocks exhibit uniform primitive mantle-normalized trace element patterns with enrichment in Rb, Th, U and Pb and depletion in Sr, Nb, Hf and Ti. These dated zircon grains have consistent negative ε Hf (t) values of −6.2 to −2.8 and T DM2 ages of ca. 2.97–3.16 Ga, indicative of Mesoarchean crustal materials as their magma source. Considering the existence of the ca. 2.36 Ga regional high-grade tectono-metamorphic event, we propose that the ca. 2.36 Ga monzogranites were most likely generated in the early stage of post-collisional extension. Therefore, the southwestern Yangtze Block likely experienced a collision event during ca. 2.40–2.36 Ga, indicative of the involvement of the Yangtze Block in the ca. 2.5–2.3 Ga Arrowsmith orogeny of Laurentia. In addition, a series of accretionary events might also have occurred in the western Yangtze Block before the final assembly of the Columbia supercontinent, implying a tight spatial connection between the Yangtze Block and northwestern Laurentia within this global-scale supercontinent. [ABSTRACT FROM AUTHOR]

Tectonic regimes display different styles worldwide during the early Paleoproterozoic ranging from plate tectonic slowdown or shutdown to vigorous subduction-related magmatism. Here we report a suite of early Paleoproterozoic granitoids from the Quanji Massif in northwestern China that provides potential insights on the tectonic regime in this period. The granitoids formed at 2.37–2.34 Ga as evidenced by LA-ICP-MS zircon U-Pb ages. These dioritic to granitic rocks with amphibole and biotite as the major mafic minerals display a wide range of SiO 2 (55.8–66.2 wt%), low to moderate MgO (1.4–4.1 wt%), low to high K 2 O (1.6–5.9 wt%) and Al 2 O 3 (16.3–21.5 wt%), with Mg# values in the range of 36–47 and relatively low Cr (7.7–79.2 ppm) and Ni (2.3–19.3 ppm) concentrations. Geochemically they correspond to high‑potassium calc-alkaline I-type granitoids, with some showing dominantly adakitic but minor A-type affinities. Both the I-type and A-type granitoids show moderately fractionated LREE to HREE and moderately to weakly negative Eu anomalies. However, the adakitic granitoids display strongly fractionated REE patterns and weak negative to positive Eu anomalies. All the rock types from this suite show enrichment in LILEs and LREEs and depletion in HFSEs (Ta, Nb). The Nd-Hf isotope data suggest that the granitoids were sourced from Mesoarchean to Neoarchean metamafic rocks in the lower crust. The coeval nature of the complex genetic types of rocks in this suite suggest that their precursor magmas formed in an extensional tectonic regime similar to those previously reported for the ~ 2.39–2.37 Ga granitoids in central to eastern domains of the Quanji Massif. Our new results in conjunction with those from previous studies suggest protracted post-collisional magmatism lasting for > 50 Myr along the periphery Quanji Massif following the cessation of plate subduction in the early Paleoproterozoic. [ABSTRACT FROM AUTHOR]

Deye 1 Well (DY 1 Well) completed in 2013 is the first drilling well that reached the early Paleoproterozoic crystalline basement in the northeastern Qaidam basin. This paper analyzes the drilling core samples from DY 1 Well. Petrology and geochemistry indicate that the drilling core samples belong to high-Na trondhjemite. LA-ICP-MS zircon dating for the drilling core samples yields a weighted mean 207 Pb/ 206 Pb age of 2383.1 ± 6.3 Ma, which is consistent with its upper interception age. Meanwhile, the geochemical characteristics and the deformation degree of high-Na trondhjemite are significantly different from its adjacent gneisses and the Mohe quartz-dioritic rocks in the Quanji Massif. It implies that the basement of the Qaidam basin under thick Cenozoic sediments may be different from its surrounding outcrops, and differential crustal attributes lead to intensely differential Cenozoic vertical motions between basins and mountains. Meanwhile, the widespread familiarity between the Qaidam and Tarim basins implies that the basement of the Qaidam basin may be a part of the Tarim Block during the Precambrian. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Xiaoqinling area is widespread of the ∼2.3 Ga Xiaohe granitic plutons. • The REE patterns and Sr/Y and δEu values of granites vary with source depth of magmas. • The Xiaohe granite is A-type granite emplaced in an extensional setting. • The Xiaohe granite was intruded by the ∼1.8 Ga granite. The early Paleoproterozic is generally considered as a worldwide tectonic quiescent period. It is unusual that widespread early Paleoproterozoic magmatism has been identified in the North China Craton (NCC), especially in the Xiaoqinling Terrane at the southern NCC. The Xiaohe granite occurs along the southern margin of the Xiaoqinling Terrane and intrudes the lower portion of the Taihua Supergroup (gneisses). Previous data suggest the emplacement time of the Xiaohe granite ranging from the early to late Paleoproterozoic, leaving a controversy over 500 Ma. To accurately constrain the age, genesis and tectonic setting of the Xiao granite, we have carried out a comprehensive study and here present new petrographical, geochronological, and isotope and element geochemical data. It is confirmed that the Xiaohe granite is dominated by the ca. 2.3-Ga monzogranite and locally intruded by the Guijiayu granites at 1.82 ± 0.05 Ga. Three samples from the Xiaohe granite yield consistent zircon U − Pb ages of ca. 2.3 Ga, and ɛ Hf (t) values showing mixing of juvenile and recycled continental crust sources. The Xiaohe granite are characterized by high SiO 2 (70.7–79.6 %) and high alkali (5.67–10.15 %), belong to calc-alkaline to shoshonite series and show weak peraluminous feature with A/CNK values around 1.1. Its geochemical characteristics are similar to those of A-type granites formed involcani arc or syn- to post-collision tectonic settings. Samples also display eastward decrease of Sr/Y, (La/Yb) N and δEu values, and weakening REE fractionation, indicating an eastward increase of plagioclase in residue during partial melting of the crust, and the magma sources become shallow eastwardly. Hence it is concluded that the Xiaohe granite was formed in a widespread granitic event associated with continental collision or terrane amalgamation. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Lower Wulashan Group in Daqingshan, northwestern NCC records magmatic zircon ages of 2455–2382 Ma. • Intrusive rocks intruding the Lower Wulashan Group have magmatic zircon ages of 2436–2362 Ma. • It is for the first time to identify early Paleoproterozoic supracrustal rocks in the area. • The Lower Wulashan Group and related intrusive rocks formed in a continental environment. • Three main magmatic episodes of the late Neoarchean to late Paleoproterozoic have been identified. Early Paleoproterozoic supracrustal rocks are relatively rare worldwide and only a few have been reported in the North China Craton (NCC). Daqingshan is a typical area of the Khondalite Belt, northwestern NCC, where early Precambrian supracrustal and intrusive rocks are widely distributed, although the precise age of all units remains unconfirmed. The Lower Wulashan Group is mainly composed of acidic to mafic volcanic and volcano-sedimentary rocks that have undergone amphibolite to granulite facies metamorphism; it was previously considered to be of Mesoarchean age. This study utilized integrated field and petrographic work, whole-rock geochemistry, and Nd whole-rock and zircon U-Pb-Hf isotopic analyses on the Lower Wulashan Group and related intrusive rocks. SHRIMP U-Pb dating of eight samples from the supracrustal rocks, interpreted as metavolcanics, yielded magmatic zircon ages of 2455–2382 Ma, thus for the first time identifying early Paleoproterozoic supracrustal rocks in the Daqingshan area. Thus it is of great importance for understanding the Precambrian evolution of the NCC as well as the Earth because this is within the period when magmatism was globally weak. Six samples from a variety of intrusive rocks have zircon U-Pb ages of 2436–2362 Ma, thus further confirming the depositional ages of the supracrustal rocks. These rocks include meta-alkali basalt, and are high in total rare earth element contents and have magmatic zircon ε Hf (t) values of −3.00 to +6.62 and crustal model ages of 3.12–2.52 Ga (38 analyses), and whole-rock ε Nd (t) of +1.0 to +2.6 with crustal model ages of 2.74–2.60 Ga (5 analyses). It is considered that the early Paleoproterozoic supracrustal rocks of the Lower Wulashan Group and related intrusive rocks formed in a continental environment, but more work is required to determine the tectonic regime (extension or subduction). [ABSTRACT FROM AUTHOR]

A global database of zircon ages from both granitoids and detrital sediments shows an exceptional and robust age gap between 2.45 and 2.20 Ga. The early Paleoproterozoic magmatism dramatically decreased on the Earth, which was proposed to relate to the global plate tectonic shutdown. However, the available data indicate that 2.45–2.20 Ga magmatic rocks are widespread in the Taihua Complex during the quiet interval. The Taihua Complex is located in both the Lushan and Xiaoqinling areas along the southern segment of North China Craton (NCC). The Complex is composed mainly of a gneiss series and the Khondalite-dominated supracrustal rocks. There was an original unconformable relationship between the two rock associations. The latter occurs as a linear structural belt and was named the Khondalite Belt. The gneiss series in the Lushan area has an age of 2.85–2.72 Ga, whereas the Xiaoqinling region contains widespread tonalitic–trondhjemitic–granodioritic gneisses with ages of 2.45–2.20 Ga. Significant variations of Hf isotopes in zircons and whole-rock ɛ Nd( t ) values suggest that these rocks were produced by variable mixing of a juvenile materials with older crust in an Andean-type continental margin arc or island arc setting. The depositional age of the sedimentary protoliths of the khondalite series can be roughly constrained in the period between 2300 and 1970 Ma. It has been considered that they were deposited in a stable continental margin environment. The U–Pb dating of metamorphic zircons from the Taihua Complex suggest that the southern NCC underwent a polyphase tectonic evolution during the period 1.97–1.82 Ga, and the peak metamorphism coeval with crustal thickening has occurred at ∼1.94 Ga. [ABSTRACT FROM AUTHOR]

The Lüliang Complex is located at the western margin of the middle segment of the Trans-North China Orogen, along which the Western and Eastern Blocks amalgamated to form the basement of the North China Craton. The complex consists of the Paleoproterozoic granitic plutons and meta-supracrustal rocks, of which the latter are subdivided into the Jiehekou, Lüliang, Yejishan, and Heichashan/Lanhe Groups. A meta-volcanic rock from the Yejishan Group gives a magmatic zircon U–Pb age of 2188 ± 48 Ma and ε Hf (t) values of + 0.06 to + 5.42. Based on the geochemical characteristics, four different ~ 2.2 Ga igneous rock suits have been identified in the Lüliang Complex. The calc-alkaline basalts and andesites show the geochemical features of typical ‘normal’ arc volcanics with pronounced LREE enrichments relative to HREE, negative Nb, Ta, P and Ti anomalies and ε Nd (t) values of − 2.69 to + 2.14. The adakitic rocks are characterized by high Na 2 O/K 2 O ratios, weak to positive Eu anomalies, positive Sr and Ba but negative Nb and Ti anomalies, and relatively clustered and near to zero ε Nd (t) values. The Nb-enriched basalts and andesites have higher Nb, Zr and TiO 2 contents, higher Nb/Ta (14.4–19.3) and Nb/U (20.6–23.2) ratios than the majority of arc basalts and andesites and relatively variable ε Nd (t) values (− 1.54 to + 3.02). The magnesian andesites are characterized by anomalously high MgO, Cr and Ni contents and have ε Nd (t) values of − 3.90 to + 1.17. The occurrence of adakitic rocks, Nb-enriched basalts and andesites and magnesian andesites has been described from many modern arcs featuring subduction of oceanic slab. Therefore, we suggest that similar mechanism may have played an important role in the production of the ~ 2.2 Ga igneous rocks in the Lüliang Complex and thus the final collision between the Eastern and Western Blocks along the TNCO must have happened at some time after ~ 2.2 Ga. [ABSTRACT FROM AUTHOR]

• The Jingwan mafic intrusions in the south North China Craton ware emplaced at 2301 ± 16 Ma. • The intrusions were originated from melts of slab fluids-metasomatized mantle wedge in a subduction zone. • The prevalence ca. 2.3 Ga magmatic events of the TNCO were generated in a continental margin arc setting. • The early Paleoproterozoic subduction likely continued from ca. 2.5 Ga to ca. 2.3 Ga, at least 200 Ma. The time of 2.45–2.2 Ga in the early Paleoproterozoic era is called as 'Quiet Interval' because of the decreased magmatic activity worldwide. However, tectonic evolution of old continents during this time interval is still in dispute due to the rare geological records, especially for magmatism. In the southern North China Craton (NCC), the Jingwan mafic intrusions intruded into the Songshan Group and its zircon U-Pb dating yielded a weighted mean 207Pb/206Pb age of 2301 ± 16 Ma, and thus they are the only ca. 2.3 Ga mafic magmatic records founded in this region. These diabases belong to low-K tholeiitic series with relatively low K 2 O (0.1–0.7 wt%) and total alkalis (Na 2 O + K 2 O) (2.4–4.7 wt%). They have low SiO 2 (44.8–54.1 wt%), slightly variable Fe 2 O 3 T (10.1–14.4 wt%), Al 2 O 3 (14.8–17.0 wt%), CaO (5.5–10.6 wt%), and medium to high MgO (6.1–10.8 wt%) and Mg# values (58–65). The rocks display LREE enrichment ((La/Yb) N = 3.02–3.58) without obvious Eu anomaly (Eu/Eu* = 0.87–1.18). They are characterized by obvious depletion in Nb, Zr and Ti, and enrichment of Sr, Ba and Pb, indicative of geochemical features of island arc magmas. The rocks have experienced crystallization from clinopyroxene to orthopyroxene, then plagioclase, suggesting the hydrous fractionation order. They also exhibit variable ε Nd (t) values ranging from − 0.2 to + 0.8 and zircon ε Hf (t) values from − 3.0 to + 6.6. These features suggest that the mafic intrusions are formed by partial melting of a garnet-spinel lherzolite and derived from an enriched mantle source metasomatized by slab-derived fluids at a shallow depth. Combined with the previous reported magmatic records, the ca. 2.3 Ga magmatic activity may be a result of the oceanic slab subduction beneath the Eastern Block of the NCC, and the subduction probably continue throughout the early Paleoproterozoic from ca. 2.5 Ga to ca. 2.3 Ga, at least 200 Ma. Therefore, the prevalence of early Paleoproterozoic magmatic activities in the southern NCC indicate that the tectonic activity did not shutdown globally during the interval of the 'tectono-magmatic lull'. [ABSTRACT FROM AUTHOR]

Although life already existed in the Paleoarchean (ca. 3.8 Ga), rapid development of the biosphere began only in the Paleoproterozoic, from 2.4–2.3 Ga; this eventually resulted in the emergence of multicellular organisms. This event coincided in time with the irreversible replacement of tectonomagmatic activity, when high-Mg magmatism of the Early Precambrian, derived from depleted mantle, was irreversibly replaced by geochemically enriched Fe-Ti basalts similar to Phanerozoic intraplate magmas. The new type of magmas was characterized by the increased and high content of Fe, Ti, Cu, P, Mn, alkalis, LREE, and other incompatible elements (Zr, Ba, Sr, U, Th, F, etc.), which are required for metabolism and fermentation. It is proposed that this event promoted changes in ecological conditions and rapid development of the biosphere, providing the Earth’s surface with qualitatively new biotic material. [ABSTRACT FROM AUTHOR]

Highlights: [•] The Dengfeng and Taihua Complexes in the southern Trans-North China Orogen consist mainly of TTG rocks. [•] Geochronology reveals 4 magmatic episodes in the southern Trans-North China Orogen between 2.07 and 2.85Ga. [•] Three early episodes of TTG were derived from thickened lower crust. [•] The final magmatic episode involved crustal reworking due to orogenic collapse. [•] Episodic crustal growth happened prior to the final assembly of the North China Craton. [Copyright &y& Elsevier]

Abstract: A variety of early Paleoproterozoic supercontinents or supercratons have been proposed, including Kenorland, Superia and Vaalbara. Improved geologic knowledge of the Churchill Province, Canadian shield, suggests that the classical Kenorland configuration, with linked Rae and Hearne cratons, is invalid and represents a younger ca. 1.9Ga Nuna configuration. We review the early Paleoproterozoic tectonic history of the Rae craton and propose that the ca. 2.55–2.50Ga MacQuoid and 2.50–2.28Ga Arrowsmith orogens represent critical piercing points for supercontinent reconstruction. Utilizing the StratDB and DateView databases, we have identified nearly two dozen regions worldwide that show effects of these orogenic events, including the Rae, Gawler–Mawson, peninsular India, West Africa, Amazonia, North China, and Sask crustal blocks. We propose that these cratonic blocks form a distinct Rae family lineage. Utilizing new time-space plots for the Rae family and components of the Superia and Vaalbara supercratons, we demonstrate that the Rae family lacks the distinctive early Paleoproterozoic depositional and glaciogenic record characteristic of Superia and Vaalbara, but has an important contemporaneous record of juvenile crust formation and contractional orogenesis. We propose the collective history of the Rae family is best reconciled if it represents the now dispersed blocks of a third earliest Paleoproterozoic supercraton that we term Nunavutia. In this model the magmatic and tectonometamorphic record of these cratons includes an early 2.55–2.45Ga period of interior collisional orogenesis in which the supercraton amalgamated, and a later phase of long-lived peripheral orogenesis (2.45–2.28Ga) prior to its partial break-up at ca. 2.05Ga. Forming within an otherwise globally quiescent period, the history of the Rae family is important for assessment of constrasting models of early Paleoproterozoic geodynamic activity. [Copyright &y& Elsevier]

The Taihua Complex in the Xiaoqinling area of the southern Trans-North China Orogen (TNCO) records extensive magmatism during the early Paleoproterozoic. This contrasts with the tectono-magmatic quiescence recorded globally at this time. Based on zircon U−Pb geochronological and whole-rock geochemical data, the 2.36–2.30 Ga granitic gneisses in the Taihua Complex can be subdivided into three groups. Group-1 gneisses (2.36–2.33 Ga), mainly in the Dumutai area, are high-K 2 O granitoid rocks, which record the earliest magmatism. These rocks have fractionated rare earth elements (REE) patterns, marked negative Eu−Sr anomalies, and variable whole-rock ε Nd (t) (−1.67 to +2.41) and ε Hf (t) values (−0.89 to +3.41), and were likely derived by partial melting of a mixture of pre-existing tonalite–trondhjemite–granodiorite (TTG) and K-rich rocks with residual plagioclase in the source at high-temperature and low-pressure conditions. Group-2 gneisses (2.33–2.31 Ga), mainly in the Jialu and Xitongyu areas, are granitoid rocks that formed after the Group-1 gneisses. These rocks have less fractionated REE patterns, low La/Yb and Sr/Y ratios, and slightly positive to negative whole-rock ε Nd (t) (−3.91 to +2.00) and ε Hf (t) values (−7.99 to +0.87), which resulted from high-degree partial melting of ancient crust in an extensional setting. Group-3 gneisses (~2.30 Ga) are TTG rocks from the Bayuan area, which represent the youngest magmatism. These rocks have high La/Yb and Sr/Y ratios, high MgO, Cr, and Ni contents, and negative whole-rock ε Nd (t) (−1.71 to −1.67) and ε Hf (t) values (−0.57 to −0.10), which indicate derivation by partial melting of delaminated lower crust and interaction with mantle materials. Samples from all groups have variable zircon ε Hf (t 7/6) (−6.38 to +7.70) and δ18O values (3.97‰ − 6.79‰), indicative of a heterogeneous magmatic source. Most zircons have slightly positive to negative ε Hf (t 7/6) values, indicating significant reworking of ancient crustal materials and limited crustal growth during this period. The age, geochemistry, and petrogenesis of the studied granitoid rocks record orogenic collapse and a transition from post-collisional extension to crustal delamination in the early Paleoproterozoic. This followed late Archean subduction–collision–accretion processes in the southern NCC. • Gneisses of the Xiaoqinling Taihua Complex record extensive magmatism at ca. 2.3 Ga. • The Xiaoqinling Taihua gneiss protoliths were formed by reworking of lower crust. • The ca. 2.3 Ga magmatism in the southern NCC was related to orogenic collapse. [ABSTRACT FROM AUTHOR]

It is debated whether global-scale tectono-magmatic quiescence prevails on the Earth during the early Paleoproterozoic. The early Paleoproterozoic meta-mafic and intermediate rocks in the southwestern Yangtze Block of South China could provide an opportunity to constrain not only the tectonic evolution of the Yangtze Block itself but also augment our understanding of the global tectono-magmatic lull during the early Paleoproterozoic. Zircon U Pb geochronological study indicates that the meta-mafic rocks were emplaced at ca. 2.32 Ga, whereas the intermediate rocks were emplaced at ca. 2.35 Ga. These two lithologies are characterized by subduction-related whole-rock geochemical (such as depleted Nb, Ta and enriched Rb, K, Pb) and unradiogenic Nd Hf isotopic signatures (ε Hf (t) < 0, ε Nd (t) < 0), implying a derivation from a geochemically enriched lithospheric mantle modified by ancient subduction. Thermodynamic modeling further suggests that the intermediate rocks are products of the AFC process between mantle-derived basaltic magma and TTG-like basement rocks at shallow crustal levels. We interpret this as occurring within a post-orogenic extensional setting. Integrated with the published work, we further posit that the Yangtze Block experienced a tectonic regime transition from compressive orogenesis to post-orogenic extension during the early Paleoproterozoic, and the magmatic activities in several crustal blocks are still active until ~2.3 Ga and therefore places important constraints on the beginning of the tectono-magmatic lull. [Display omitted] • 2.35–2.32 Ga mafic-intermediate magmatism is identified in the SW Yangtze Block. • Mafic-intermediate rocks in this study were derived from the lithospheric mantle. • Tectonic transition from orogeny to post-orogenic extension at ~2.35 Ga in Yangtze. [ABSTRACT FROM AUTHOR]

Tectonic regimes took different forms worldwide during the early Paleoproterozoic, ranging from a slowing or halting of plate tectonics to vigorous subduction-related magmatism. A detailed study is conducted on the Delingha granitoid pluton in the Quanji Massif of northwestern China to reveal the crustal evolution of this Precambrian microcontinent and to provide potential insight on complex and heterogeneous evolutionary processes occurring in this period. The Delingha pluton was mainly composed of gneissic biotite granite and gneissic granodiorite, which formed at ca. 2.48 – 2.44 Ga and 2.38 – 2.35 Ga, respectively, as evidenced by LA-ICP-MS zircon U-Pb ages. The gneissic biotite granite exhibited high-K I-type granite affinities and variable zircon ε Hf (t) values (−12.9 −4.7) with a major peak of approximately 2.8 and a secondary peak of approximately 3.9, indicating that the source rock was dominated by heterogeneous mafic crustal materials. The gneissic granodiorite shows A-type granite affinities and a nearly unimodal distribution of zircon ε Hf (t) values (−3.1 −4.0, with a peak of approximately 1.5). These data indicate that the gneissic granodiorite was mainly sourced from Archean mafic igneous rocks. Our study suggests that the gneissic biotite granite formed in a subduction-related environment while the gneissic granodiorite formed in a post-collisional tectonic regime. Alongside previous studies on other Siderian granitoids in the Quanji Massif, we propose a tectonic evolution model, including (1) plate subduction occurring before 2.44 Ga; (2) a collision occurring from ca. 2.43 to ca. 2.40 Ga; (3) a post-collisional extension occurring from ca. 2.39 to ca. 2.32 Ga. This tectonic evolution reveals that the operation of plate tectonics continued during the Siderian and that a slowdown or pause might have occurred in the Quanji Massif after ca. 2.3 Ga. Unlabelled Image • A 2.48 – 2.44 Ga subduction-related granitoid was recognized in the Quanji Massif. • The A-type granitoid suggests a post-collision setting during 2.38-2.35 Ga. • An orogenic cycle from subduction to collision and then post-orogeny is revealed. [ABSTRACT FROM AUTHOR]