Fresh insights into the onset of big mantle wedge beneath the North China Craton

The onset of the big mantle wedge(BMW)structure beneath the North China Craton remains debated.Research on the genesis of Late Mesozoic granites associated with gold deposits in the Jiaodong Peninsula above the BMW could provide fresh insights into this question.The monzogranite from the Zhaoxian-Shaling gold district was intruded during 154-148 Ma.This I-type granite has high-K calc-alkaline and metaluminous characteristics.The monzogranite formed at medium temperatures(718-770℃)and was generated in a thickened lower crust at depths within the stability field of garnet.The monzogranite’s high zircon Ce^(4+)/Ce^(3+)and Eu_(N)/Eu_(N)^(*)values and low FeOT/MgO ratios,suggest that it formed in a high oxygen environment.Its variableε_(Hf)(t)values with T_(DM2)of 1.93-2.87 Ga imply that it originated from the melting of ancient crust basement,with contributions from mantle-derived materials.The granite’s enrichment in LREEs and LILEs,and depletion in HREEs and HFSEs,along with its trace element tectonic discrimination diagrams and medium Sr/Y,indicate an adakite affinity in an active continental margin setting.The transition from S-type granites to I-type granites and finally to A-type granites observed in the eastern part of North China Craton suggests a shift in the tectonic environment from compression to extension.This change is also reflected in the transition from flat subduction to steep subduction.Therefore,the monzogranite was formed in a tectonic transition setting triggered by a change in the subduction angle of the PaleoPacific Ocean slab during the Late Jurassic.This event may have marked the initiation of the BMW above the North China Craton.

Rheological Evidence of the Lithospheric Destruction of the Eastern Block of the North China Craton

The Eastern Block of the North China Craton(NCC)(Fig.1)has undergone severe lithospheric destruction,with crustal thinning down to 100 km depth(Chen et al.,2009),contrasting sharply with the stable Kalahari and Rae cratons.However,there remains controversy over the destruction pattern(e.g.,Zhu et al.,2017).During the Early Mesozoic,crustal thickening occurred in the Xuhuai and Qinling orogens,followed by lithospheric delamination leading to crustal thinning(Chen et al.,2023).The middle and upper crustal thinning in the Yanshan and Taihang uplifts was induced by mafic magma underplating(Ji et al.,2009).

Strong Earthquake Model of North China Craton: A Case of 2023 Mw 5.5 Earthquake in Pingyuan County, Shandong Province, China

North China is one of the high-risk areas for destructive strong earthquakes in China's Mainland, with a history of numerous significant seismic events. On August 6, 2023, an Mw5.5 earthquake struck Pingyuan County, Dezhou City, in Shandong Province, China. This earthquake was the largest in the eastern North China Craton(NCC) since the Tangshan earthquake of 1976. Due to the absence of surface ruptures, the fault responsible for the Pingyuan Mw5.5 earthquake remains unclear. To reveal the subsurface geological structure near the earthquake epicenter, this study utilized highresolution two-dimensional seismic reflection profiles to interpret pre-existing faults.

Characteristics and main controlling factors of helium resources in the main petroliferous basins of the North China Craton

At present, the main controlling factors of helium accumulation is one of the key scientific problems restricting the exploration and development of helium reservoir. In this paper, based on the calculation results of He generation rate and the geochemical characteristics of the produced gas, both the similarities and differences between natural gas and He resources in the Bohai Bay, Ordos and the surrounding Songliao Basin are compared and analyzed, discussing the main controlling factors of helium resources in the three main petroliferous basins of the North China Craton. It is found that the three basins of Bohai Bay, Ordos and Songliao have similar characteristics of source rocks, reservoirs and cap rocks, that's why their methane resource characteristics are essentially the same. The calculated ~4He generation per cubic metamorphic crystalline basement in the three basins is roughly equivalent, which is consistent with the measured He resources, and it is believed that the ~4He of radiogenic from the crust is the main factor controlling the overall He accumulation in the three basins;there is almost no contribution of the mantle-derived CH_4, which suggests that the transport and uplift of mantle-derived ~3He carried by the present-day magmatic activities along the deep-large faults is not the main reason for the mantle-derived ~3He mixing in the basins. Combined with the results of regional volcanic and geophysical studies,it is concluded that under the background of the destruction of North China Craton, magma intrusion carried a large amount of mantle-derived material and formed basic volcanic rocks in the Bohai Bay Basin and Songliao Basin, which replenished mantle-derived ~3He for the interior of the basins, and that strong seismic activities in and around the basins also promoted the upward migration of mantle source ~3He. This study suggests that the tectonic zone with dense volcanic rocks in the Cenozoic era and a high incidence of historical strong earthquakes history may be a potential area for helium resource exploration.

Experimental study on reactions between alkaline basaltic melt and orthopyroxenes: constraints on the evolution of lithospheric mantle in the North China Craton

The experimental results of the reactions between an alkaline basaltic melt and mantle orthopyroxenes under high-temperature and high-pressure conditions of 1300–1400℃ and 2.0–3.0 GPa using a six-anvil apparatus are reported in this paper.The reactions are proposed to simulate the interactions between melts from the asthenospheric mantle and the lithospheric mantle.The starting melt in the experiments was made from the alkaline basalt occurring in Fuxin,Liaoning Province,and the orthopyroxenes were separated from the mantle xenoliths in Damaping,Hebei Province.The results show that clinopyroxenes were formed in all the reactions between the alkaline basaltic melt and orthopyroxenes under the studied P–T conditions.The formation of clinopyroxene in the reaction zone is mainly controlled by dissolution–crystallization,and the chemical compositions of the reacted melt are primarily infl uenced by the diff usion eff ect.Temperature is the most important parameter controlling the reactions between the melt and orthopyroxenes,which has a direct impact on the melting of orthopyroxenes and the diff usion of chemical components in the melt.Temperature also directly controls the chemical compositions of the newly formed clinopyroxenes in the reaction zone and the reacted melt.The formation of clinopyroxenes from the reactions between the alkaline basaltic melt and orthopyroxenes can result in an increase of CaO and Al_(2)O_(3) contents in the rocks containing this mineral.Therefore,the reactions between the alkaline basaltic melt from the asthenospheric mantle and orthopyroxenes from the lithospheric mantle can lead to the evolution of lithospheric mantle in the North China Craton from refractory to fertile with relatively high CaO and Al 2 O 3 contents.In addition,the reacted melts in some runs were transformed from the starting alkaline basaltic into tholeiitic after reactions,indicating that tholeiitic magma could be generated from alkaline basaltic one via reactions between the latter and orthopyroxene.

In situ U-Pb dating and trace elements of magmatic rutile from Mujicun Cu-Mo deposit,North China Craton:Insights into porphyry mineralization

Porphyry Cu(Mo-Au)deposit is one of the most important types of copper deposit and usually formed under magmatic arc-related settings,whilst the Mujicun porphyry Cu-Mo deposit in North China Craton uncommonly generated within intra-continental settings.Although previous studies have focused on the age,origin and ore genesis of the Mujicun deposit,the ore-forming age,magma source and tectonic evolution remain controversial.Here,this study targeted rutile(TiO_(2))in the ore-hosting diorite porphyry from the Mujicun Cu-Mo deposit to conduct in situ U-Pb dating and trace element composition studies,with major views to determine the timing and magma evolution and to provide new insights into porphyry Cu-Mo metallogeny.Rutile trace element data show flat-like REE patterns characterized by relatively enrichment LREEs and depleted HREEs,which could be identified as magmatic rutile.Rutile U-Pb dating yields lower intercept ages of 139.3–138.4 Ma,interpreted as post magmatic cooling timing below about 500℃,which are consistent or slightly postdate with the published zircon U-Pb ages of diorite porphyry(144.1–141.7 Ma)and skarn(146.2 Ma;139.9 Ma)as well as the molybdenite Re-Os ages of molybdenum ores(144.8–140.0 Ma).Given that the overlap between the closure temperature of rutile U-Pb system and ore-forming temperature of the Mujicun deposit,this study suggests that the ore-forming ages of the Mujicun deposit can be constrained at 139.3–138.4 Ma,with temporal links to the late large-scale granitic magmatism at 138–126 Ma in the Taihang Orogen.Based on the Mg and Al contents in rutile,the magma of ore-hosting diorite porphyry was suggested to be derived from crust-mantle mixing components.In conjunction with previous studies in Taihang Orogen,this study proposes that the far-field effect and the rollback of the subducting Paleo-Pacific slab triggered lithospheric extension,asthenosphere upwelling,crust-mantle interaction and thermo-mechanical erosion,which jointly facilitated the formation of dioritic magmas during the Early Cretaceous.Subsequently,the dioritic magmas carrying crust-mantle mixing metallic materials were emplaced and precipitated at shallow positions along NNE-trending ore-controlling faults,eventually resulting in the formation of the Mujicun Cu-Mo deposit within an intracontinental extensional setting.

Paleoproterozoic volcanic rocks in the southern margin of the North China Craton, central China:Implications for the Columbia supercontinent

The volcanic rocks of the Xiong’er Group are situated in the southern margin of the North China Craton(NCC).Research on the Xiong er Group is important to understand the tectonic evolution of the NCC and the Columbia supercontinent during the Paleoproterozoic.In this study,to constrain the age of the Xiong’er volcanic rocks and identify its tectonic environment,we report zircon LA-ICP-MS data with Hf isotope,whole-rock major and trace element compositions and Sr-Nd-Pb-Hf isotopes of the volcanic rocks of the Xiong’er Group.The Xiong’er volcanic rocks mainly consist of basaltic andesite,andesite.dacite and rhyolite,with minor basalt.Our new sets of data combined with those from previous studies indicate that Xiong’er volcanism should have lasted from 1827 Ma to 1746 Ma as the major phase of the volcanism.These volcanics have extremely low MgO.Cr and Ni contents,are enriched in LREEs and LILEs but depleted in HFSEs(Nb,Ta,and Ti),similar to arc-related volcanic rocks.They are characterized by negative zirconεHft values of-17.4 to 8.8,whole-rock initial 87Sr/86Sr values of 0.7023 to 0.7177 andεNd(t)values of-10.9 to 6.4.and Pb isotopes(206Pb/204Pb=14.366-16.431,207Pb/204Pb=15.106-15.371,208Pb/204Pb=32.455-37.422).The available elemental and Sr-Nd-Pb-Hf isotope data suggest that the Xiong’er volcanic rocks were sourced from a mantle contaminated by continental crust.The volcanic rocks of the Xiong’er Group might have been generated by high-degree partial melting of a lithospheric mantle that was originally modified by oceanic subduction in the Archean.Thus,we suggest that the subduction-modified lithospheric mantle occurred in an extensional setting during the breakup of the Columbia supercontinent in the Late Paleoproterozoic,rather than in an arc setting.

Late Jurassic-Early Cretaceous Plutonism in the Northern Part of the Precambrian North China Craton:SHRIMP Zircon U-Pb Dating of Diorites and Granites from the Yunmengshan Geopark,Beijing

The Yunmengshan Geopark in northern Beijing is located within the Yanshan range. It contains the Yunmengshan batholith, which is dominated by two plutons： the Yunmengshan gneissic granite and the Shicheng gneissic diorite. Four samples of the Yunmengshan gneissic granite give SHRIMP zircon U-Pb ages from 145 to 141 Ma, whereas four samples of the Shicheng gneissic diorite have ages from 159 Ma to 151 Ma. Dikes that cut the Yunmengshan diorite record SHRIMP zircon U-Pb age of 162±2 and 156±4 Ma. The cumulative plots of zircons from the diorites show a peak age of 155 Ma, without inherited zircon cores, and the peak age of 142 Ma for granite is interpreted as the emplacement age of the Yunmengshan granitic pluton, whose igneous zircons contain inherited zircon cores. The data presented here show that there were two pulses of magmatism： early diorites, followed c13 Ma later by true granites, which incorporated material from an older continental crust.

Triassic Granitic Magmatism at the Northern Margin of the North China Craton: Implications of Geochronology and Geochemistry for the Tectonic Evolution of the Central Asian Orogenic Belt

The early Mesozoic marked an important transition from collisional orogeny to post-orogenic extension at the northern margin of the North China Craton(NCC). In this study, we undertook zircon U-Pb dating and whole-rock majorand trace-element geochemical analyses of early Mesozoic granitic rocks in the Chifeng area to establish their geochronological framework, petrogenesis, and implications for the tectonic evolution of the eastern Central Asia Orogenic Belt(CAOB). Zircon U-Pb dating results show that these rocks were emplaced in three stages during the Triassic:(1) syenogranites during 250-248 Ma,(2) granodiorites during 244-243 Ma, and(3) monzogranites and granodiorites during 232-230 Ma. These Triassic granitoids belong to the high-K calc-alkaline series and are evolved I-type granites. They have high SiO2 and low Mg O contents with enrichments in light rare-earth elements, Zr, Hf, Rb, Th, and U, and depletions in Ba, Nb, Ta, Sr, and Eu. These geochemical data indicate that the granitoids were derived from partial melting of a lower-crustal source under relatively low-pressure conditions and subsequently underwent extensive fractional crystallization. Considering both the geochemical data and regional geological information, we propose that the 250-248 Ma syenogranites were emplaced in an extensional environment linked to slab break-off after closure of the Paleo-Asian Ocean(PAO) along the Solonker-Xra Moron-Changchun suture zone. The 244-243 Ma granodiorites were formed in a compressional orogenic setting during collision between the Erguna-Xing’an-Songliao composite block and the NCC. The 232-230 Ma granodiorites and monzogranites were emplaced during the transition from compressional orogeny to post-orogenic extension. Overall, the early Mesozoic tectonic evolution of the Chifeng area can be divided into three main stages:(1) closure of the Paleo-Asian Ocean and extension related to slab break-off during the Early Triassic;(2) continuous collisional compression during the Middle Triassic after closure of the PAO;and(3) post-orogenic extension during the Late Triassic, most probably due to lithospheric delamination after amalgamation of the Erguna-Xing’an-Songliao composite block and the NCC.

Hydrothermal Origin of Early Permian Chert Nodules in the Central North China Craton Linked to Northern Margin Cratonic Activation

Sedimentary chert phases from the Archean to the present are widely used to trace sedimentary environments and tectonic settings.Recently,chert nodules occurring within carbonates have been the subject of possible hydrothermal or biogenic origin,in lieu of a diagenetic origin.However,chert nodules from a vast cratonic basin represent extremely rich silica accumulations but less noted is how they respond to submarine hydrothermal activity(and/or surface siliceous organism productivity).The links between the cratonic-type chert depositions and environmental changes regarding cratonic evolution need to be revisited at a large temporal-spatial scale.The chert nodules are widespread throughout the Lower Permian Taiyuan Formation in the North China Craton(NCC).Several Taiyuan chert-rich successions across the NCC have been selected to study possible links between chert deposition and cratonic evolution in scenario of partial cratonic activation of the northern NCC margin during the Late Paleozoic.Based on stratigraphic correlation,the chert nodules are ubiquitously,evenly distributed throughout the Taiyuan Formation at a large craton-basin scale from the northern to southern interior NCC.Petrological results,elemental abundances,together with silicon and oxygen isotopic compositions of chert samples infer significant hydrothermal contributions for the silica accumulations.Therefore,the cratonic-scale chert depositions of hydrothermal origin infer a giant and remote silica reservoir,linking to the large igneous province and magmatism in the NCC northern margins.The Taiyuan chert nodules could be unique marine sedimentary archives recording the Late Paleozoic NCC partial activation,which also generated continental records of igneous rocks,bauxites and tuffs.The strong tectonics of the northern margin,south-dipping topography and northward transgression of the Early Permian NCC facilitated the chert deposition on the shallow marine platform in the cratonic interior.

Late Paleozoic to early Mesozoic volcanic-sedimentary history of the southeastern margin of the Central Asian Orogenic Belt:Timing of uplift of the Inner Mongolia paleo-uplift

The Kulun region is located in the eastern Bainaimiao arc belt on the southeastern margin of the Central Asian Orogenic Belt(CAOB),adjacent to the North China Craton(NCC)to the south.This region records the closure of the PaleoAsian Ocean during the Paleozoic to early Mesozoic and is key to study the tectonic evolution of the northern margin of the NCC.We conducted zircon U-Pb geochronology and Hf isotope analysis of volcanic-sedimentary and intrusive rocks in the Kulun region.The volcanic-sedimentary rocks were previously assigned an early Carboniferous age,but include volcanic rocks with ages of 267–266 Ma and sedimentary rocks with youngest detrital zircon age peaks of 265–244 Ma,which were intruded by a granite with an age of 242 Ma.This indicates that these rocks are actually middle Permian to Middle Triassic in age(267–242Ma)and correspond to the Qingfengshan and Liujiagou formations.Moreover,two volcanic rock samples have highεHf(t)values(+1.6 to+16.1)and relatively young two-stage Hf model ages(1095–327 Ma),indicating their sources associated with the CAOB.The age spectra and Hf isotopic characteristics of detrital zircons from the sedimentary rocks suggest that,during the middle Permian to Middle Triassic,the sedimentary provenance in the Kulun region was mainly the CAOB.However,by the Early Jurassic,the provenance changed to the NCC(i.e.,the Inner Mongolia Paleo-uplift,IMPU).This result,combined with the development of a series of conglomerates on the northern margin of the NCC in the Late Triassic(i.e.,Xingshikou,Xiaoyingzi,and Xiaohekou formations),indicates the Kulun region experienced an abrupt change in paleogeography during the Late Triassic,with the IMPU undergoing significant uplift and thus becoming the main sediment source in the Kulun region.Based on the Late Triassic alkaline igneous belt(235–215 Ma)in the IMPU,we speculate that this uplift was caused by detachment of the southward-subducting Paleo-Asian oceanic plate,which occurred in a post-orogenic extensional setting.The boundary between the NCC and CAOB(i.e.,the Bainaimiao arc belt)in the Kulun region is defined by the newly identified Paleoproterozoic granites(1.8 and 1.6 Ga)and our zircon geochronology and Hf isotope data.

Mesozoic multi-direction collision tectonic evolution of the Ordos Basin, China: Insights from the detrital zircon and apatite (U-Th)/He analyses

The Ordos Basin(OB)in the western part of the North China Craton(NCC),was located at the jointed area of multi-plates and has recorded the Mesozoic tectonic characteristics.Its tectonic evolution in the Mesozoic is significant to understand the tectonic transformation of the northern margin of the NCC.In this work,the detrital zircon and apatite(U-Th)/He chronological system were analyzed in the northern part of the OB,and have provided new evidence for the regional tectonic evolution.The(U-Th)/He chronological data states the weighted ages of 240‒235 Ma,141 Ma with the peak distribution of 244 Ma,219 Ma,173 Ma,147‒132 Ma.The thermal evolution,geochronological data,and regional unconformities have proved four stages of regional tectonic evolution for the OB and its surroundings in the Mesozoic:(1)The Late Permian-Early Triassic;(2)the Late Triassic-Early Jurassic;(3)the Late Jurassic-Early Cretaceous;(4)the Late Cretaceous-Early Paleogene.It is indicated that the multi-directional convergence from the surrounding tectonic units has controlled the Mesozoic tectonic evolution of the OB.Four-stage tectonic evolution reflected the activation or end of different plate movements and provided new time constraints for the regional tectonic evolution of the NCC in the Mesozoic.

Comparative Orotomy of the Archean Superior,North China,and Phanerozoic Altaid Orogenic Systems Architecture

Geological maps encode vast amounts of data about rock types,ages,chemistry,orogenic architecture and deep-time history or different tectonic units,yet these are often difficult to extract because of the way different geologists portray their results at various scales.To understand orogenesis in 4D,it is essential to uniformly integrate map data,together with geophysical data and deep geochemical mapping(Wang et al.,2023).

Geology and mineralization of the Dongping supergiant alkalic-hosted Au-Te deposit(>100 t Au)in Northern Hebei Province,China:A review

The Dongping deposit is the largest alkalic-hosted gold deposit in China containing>100 t of Au.This paper presents a new understanding for Dongping ore system,based on the previous studies.The mineralization originally occurred at 400-380 Ma,simultaneous with emplacement of the Shuiquangou alkaline complex,and was overprinted by the hydrothermal activity in the Yanshanian.Isotope compositions of ores indicate metals of the deposit are mainly provided by the Shuiquangou complex.Ore-forming fluids are characterized by increasing oxygen fugacity and decreasing sulfur fugacity,while tellurium fugacity increased in the Stage II-2 and decreased in Stage II-3.These systematic changes are closely related to the processes of mineral precipitation and fluid evolution.Sulfide precipitation from Stage Ⅰ to Stage Ⅱ was triggered by fluid boiling,which leads to the precipitation of Pb-Bi-Te,due to decrement of sulfur fugacity.Condensation of gas phase containing high concentration of H_2Te leads to precipitation of Te-Au-Ag minerals and native tellurium.Based on these hypotheses,this paper present a polyphase metallogenic model as follow.During the Devonian,fluids were released from alkaline magmas,which carried ore-forming materials form the surrounding rocks and precipitate the early ores.During the Jurassic-Cretaceous,fluorine-rich fluids exsolved from highly factionated Shangshuiquan granite,which extracted and concentrated Au from the Shuiquangou complex and the Sanggan Group metamorphic rocks,and finally formed the Dongping gold deposit.

Microdiamonds in Alkalic Dolerites from the North China Craton

Diamonds on the Earth mainly occur in volcanic rocks such as kimberlites and lamproites^([1-8]),but can also be found in ultrahigh-pressure metamorphic rocks^([9-10]),meteorites^([11])and alluvial deposits^([12]).In recent years,diamonds have been recovered from ophiolites^([13-16])and alkalic dolerites^([17-18]).The discovery of ophiolitic diamonds and alkalic dolerites diamonds has drawn significant research interests to explore the origin of this new class of diamond source and to infer the evolution of their hosting rocks[^(19-21)].This new type of diamond had been initially considered as a result of contamination.However,more and more evidences either directly or indirectly demonstrate that these diamonds are of natural origin^([16,18,19,22-24]).During a geological survey from 2012 to 2015,the geologists from Nanjing Centre of China Geological Survey discovered a large number of yellow microdiamonds in the Langan area in northern Anhui Province^([18,25-29]).The diamond-bearing rocks of these microdiamonds mainly include dolerite and olivine basalt.From 2016 to 2018,four microdiamonds in basic rocks were recovered again in the prospecting work for primary diamond deposits in the Tashan and Zhangji areas in Xuzhou,which is geographically close to Langan[30].All these microdiamonds are similar in colour and shape to ophiolite type diamonds^([31]),and show different characteristics of kimberlite and lamproite type diamonds.Cai,et al.(2019)reported the petrological characteristics of the diamondiferous rocks^([17,21,30]).In this paper,the morphology,infrared spectrum,and carbon isotope compositions of microdiamonds were analysed and discussed by Fourier infrared spectroscopy and carbon isotope test.The types of microdiamonds found in the North China Craton,the age of mantle occurrence,and the source of carbon isotopes were revealed.In the past,many deposits of macro-diamonds,mostly of TypeⅠa orⅡa,were found in the North China Craton,and they have been extensively studied.Microdiamonds recovered from the alkalic dolerites of the North China Craton were studied by FTIR and carbon isotopic.These diamonds are usually light yellow to yellow,with a few colourless,and cubic,octahedral or rhomboidal dodecahedron,and octahedron in shape.The surface characteristics of diamonds,such as dissolution,can be observed.The overall N concentration is not high,with an average of 173×10^(-6).The infrared spectra show that most of these diamonds are TypeⅠb,and C centres are found at 1344 cm^(-1).Three diamond samples are classified as TypeⅠa/Ⅰb,because of A centres and C centres in these diamonds.Two diamonds are classified as typeⅠaAB because B,B′and A centres are found co-existing.FTIR microscopic measurements from the core to the edge of the TypeⅠaAB diamond suggest a mantle residence time of approximately 550 Ma.The C isotopic analysis reveals that these diamonds are strongly depleted in 13 C.These lowδ^(13) C values of dolerites-hosted diamonds overlap with the lower ends of peridotitic diamonds and metamorphic diamonds,and the upper end of the ophiolitic diamonds.Additionally,the reason for the strong deficitδ^(13) C shown by the carbon isotope should be studied in the future.

Neoarchean(2.5-2.8 Ga) crustal growth of the North China Craton revealed by zircon Hf isotope:A synthesis

The crustal growth of the North China Craton （NCC） during the Neoarchean time （2.5--2.8 Ga） is a hotly controversial topic, with some proposing that the main crustal growth occurred in the late Neoarch- ean （2.5--2.6 Ga）, in agreement with the time of the magmatism, whereas others suggest that the main crustal accretion took place during early Neoarchean time （2.7-2.8 Ga）, consistent with the time of crustal- formation of other cratons in the world. Zircon U-Pb ages and Hf isotope compositions can provide rigorous constraints on the time of crustal growth and the evolution and tectonic division of the NCC. In this contri- bution, we make a comprehensive review of zircon Hf isotope data in combination with zircon U-Pb geochro- nology and some geochemistry data from various divisions of the NCC with an aim to constrain the Neoarchean crustal growth of the NCC. The results suggest that both 2.7--2.8 Ga and 2.5-2.6 Ga crustal growth are distributed over the NCC and the former is much wider than previously suggested. The Eastern block is characterized by the main 2.7-2.8 Ga crustal growth with local new crustal-formation at 2.5-2.6 Ga, and the Yinshan block is characterized by ~2.7 Ga crustal accretion as revealed by Hf-isotope data of detrital zircons from the Zhaertai Group. Detrital zircon data of the Khondalite Belt indi- cate that the main crustal growth period of the Western block is Paleoproterozoic involving some ~ 2.6 Ga and minor Early- to Middle-Archean crustal components, and the crustal accretion in the Trans-North China Orogen （TNCO） has a wide age range from 2.5 Ga to 2.9 Ga with a notable regional discrepancy. Zircon Hf isotope compositions, coupled with zircon ages and other geochemical data suggest that the southern margin may not be an extension of the TNCO, and the evolution and tectonic division of the NCC is more complex than previously proposed, probably involving multi-stage crustal growth and subduction processes. However, there is no doubt that 2.7--2.8 Ga magmatism and crustal-formation are more widely distributed than previ- ously considered, which is further supported by the data of zircons from Precambrian lower crustal rocks, overlying sedimentary cover, modern river sediments and Late Neoarchean syenogranites.

Archean Basement and a Paleoproterozoic Collision Orogen in the Huoqiu Area at the Southeastern Margin of North China Craton: Evidence from Sensitive High Resolution Ion Micro-Probe U-Pb Zircon Geochronology

This paper reports sensitive high resolution ion micro-probe U-Pb zircon ages for the ＂Huoqiu Group＂ and granitoids of the Early Precambrian basement in the Huoqiu area, southeastern margin of the North China Craton. The ＂Huoqiu Group＂ is similar in rock association and metamorphism to the khondalite series, apart from it containing considerable amounts of banded iron formation. All detrital zircons from the ＂Huoqiu Group＂ meta-sedimentary rocks are 3.0 Ga and 2.75 Ga, without any 2.5 Ga and younger ones, as is commonly found in Paleoproterozoic khondalite series in other areas of the North China Craton. In the Huoqiu area, 2.75 Ga and 2.56 Ga granitoids have also been identified. This basement assemblage underwent strong metamorphism during the late Paleoproterozoic （-1.84 Ga） tectonothermal event that is widely developed in the North China Craton. Thus the formation time of the ＂Huoqiu Group＂ can be constrained between 2.75 and 1.84 Ga in terms of detrital and metamorphic zircon ages. It is considered, combined with regional data, that there may be a Paleoproterozoic collision orogen extending in a NWW-SEE direction to the southern margin of the North China Craton.

Major Advances in the Study of the Precambrian Geology and Metallogenesis of the North China Craton:A Review

The North China Craton （NCC） is one of the most ancient cratons in the world and records a complex geological evolution since the early Precambrian. In addition to recording major geological events similar to those of other cratons, the NCC also exhibits some unique features such as multi- stage cratonization （late Archaean and Palaeoproterozoic） and long-term rifting during the Meso- Neoproterozoic. The NCC thus provides one of the best examples to address secular changes in geological history and metallogenic epochs in the evolving Earth. We summarize the major geological events and metallogenic systems of the NCC, so that the evolutionary patterns of the NCC can provide a better understanding of the Precambrian NCC and facilitate comparison of the NCC with other ancient continental blocks globally. The NCC experienced three major tectonic cycles during the Precambrian： （1） Neoarchaean crustal growth and stabilization; （2） Palaeoproterozoic rifting-subduction-accretion-collision with imprints of the Great Oxidation Event and （3） Meso-Neoproterozoic multi-stage rifting. A transition from primitive- to modern-style plate tectonics occurred during the early Precambrian to late Proterozoic and is evidenced by the major geological events. Accompanying these major geological events, three major metallogenic systems are identified： （1） the Archaean banded iron formation system; （2） Palaeoproterozoic Cu-Pb-Zn and Mg-B systems and （3） a Mesoproterozoic rare earth element-Fe- Pb-Zn system. The ore-deposit types in each of these metallogenic systems show distinct characteristics and tectonic affinities.

Tectonic Evolution of an Early Precambrian High-Pressure Granulite Belt in the North China Craton

A large-scale high-pressure granulite belt (HPGB), more than 700 km long, is recognized within the metamorphic basement of the North China craton. In the regional tectonic framework, the Hengshan-Chengde HPGB is located in the central collision belt between the western block and eastern block, and represents the deep crustal structural level. The typical high-pressure granulite (HPG) outcrops are distributed in the Hengshan and Chengde areas. HPGs commonly occur as mafic xenoliths within ductile shear zones, and underwent multipile deformations. To the south, the Hengshan-Chengde HPGB is juxtaposed with the Wutai greenstone belt by several strike-slip shear zones. Preliminary isotopic age dating indicates that HPGs from North China were mainly generated at the end of the Neoarchaean, assocaited with tectonic assembly of the western and eastern blocks.

Protolith ages and timing of peak and retrograde metamorphism of the high-pressure granulites in the Shandong Peninsula,eastern North China Craton

High-pressure （HP） granulites widely occur as enclaves within tonalite-trondhjemite- granodiorite （TTG） gneisses of the Early Precambrian metamorphic basement in the Shandong Peninsula, southeast part of the North China Craton （NCC）. Based on cathodoluminescence （CL）, laser Raman spec- troscopy and in-situ U-Pb dating, we characterize the zircons from the HP granulites and group them into three main types： inherited （magmatic） zircon, HP metamorphic zircon and retrograde zircon. The inher- ited zircons with clear or weakly defined magmatic zoning contain inclusions of apatites, and 207pb/206pb ages of 2915--2890 Ma and 2763--2510 Ma, correlating with two magmatic events in the Archaean base- ment. The homogeneous HP metamorphic zircons contain index minerals of high-pressure metamor- phism including garnet, clinopyroxene, plagioclase, quartz, rutile and apatite, and yield 207pb/2066pb ages between 1900 and 1850 Ma, marking the timing of peak HP granulite facies metamorphism. The retrograde zircons contain inclusions of orthopyroxene, plagioclase, quartz, apatite and amphibole, and yield the youngest 207pb/206pb ages of 1840-1820 Ma among the three groups, which we correlate to the medium to low-pressure granulite facies retrograde metamorphism. The data presented in this study suggest subduction of Meso- and Neoarchean magmatic protoliths to lower crust depths where they were subjected to HP granulite facies metamorphism during Palaeoproterozoic （1900-1850 Ma）. Subse- quently, the HP granulites were exhumated to upper crust levels, and were ovel-printed by medium to low-pressure granulite and amphibolite facies retrograde event at ca. 1840--820 Ma.