The Trans-North China Orogen (TNCO), marking the final amalgamation of the Western and Eastern Blocks of the North China Craton (NCC), provides key insights into Paleoproterozoic crustal evolution and the assembly of the Columbia supercontinent. Here, we investigate garnet-bearing amphibolites derived from mafic volcanic protoliths of the Liyanghe Formation (Zanhuang Group) in the Zanhuang Complex of the central TNCO. Petrography and phase equilibria modeling delineate a clockwise P-T trajectory suggesting a peak high-pressure (HP) amphibolite-facies stage (M-2: 1.32-1.63 GPa, 715-750 degrees C) followed by near-isothermal decompression to lower-pressure amphibolite-facies conditions (M-3: 0.61-0.88 GPa, 680-718 degrees C). Furthermore, high-Ti amphibole compositions and oriented rutile exsolution within garnet provide evidence for a cryptic granulite-facies thermal peak, the diagnostic mineral records of which were likely obliterated by pervasive suprasolidus re-equilibration. Multi-mineral LA-ICP-MS U-Pb geochronology reveals a probable temporal decoupling between peak and cooling stages: metamorphic zircon dating constrains the timing of peak metamorphism to 1870 +/- 8 Ma and 1868 +/- 8 Ma, whereas cooling phases are consistently younger, with titanite at 1810 +/- 16 Ma, rutile at 1799 +/- 12 Ma and 1805 +/- 6 Ma, and apatite at 1812 +/- 31 Ma. Our results demonstrate a prolonged deep crustal residence (similar to 60 Myr) with negligible cooling (<1 degrees C/Myr), followed by rapid exhumation at similar to 1.81 Ga with a cooling rate of 11.8(-5.8)(+23.9)degrees C/Myr. These findings support a Paleoproterozoic final collision model for the TNCO and attribute this rapid similar to 1.81 Ga exhumation to lithospheric delamination or slab break-off, marking the definitive collapse of the orogen.

The Changchengian System represents one of the earliest sedimentary covers deposited on the Archean-Paleoproterozoic basement of the North China Craton. We report zircon U-Pb-Hf isotope data for Changzhougou Formation sandstones in the Chaiguan area, central-southern Taihang Mountains. The youngest detrital zircon ages (similar to 1782 Ma) constrain the maximum depositional age to similar to 1.78 Ga. Combined with regional constraints, deposition is bracketed between similar to 1.76 and similar to 1.64 Ga. Detrital zircon age spectra exhibit a dominant peak at similar to 2.5 Ga, with secondary peaks at 2.8-2.6, 2.2-2.0 and 1.9-1.8 Ga, alongside rare similar to 3.25 and similar to 3.70 Ga grains. Coupled with Hf isotopic signatures, these diverse populations suggest derivation primarily from the basement of the Trans-North China Orogen. Although the age spectra are broadly similar to the Archean-dominated Yanliao Rift, the presence of subordinate Paleoproterozoic and minor Paleoarchean grains, coupled with a predominant southeast-to-northwest paleocurrent, implies a closer affinity with the Xiong'er Group. These results suggest deposition in an extensional setting-likely associated with the breakup of the Columbia supercontinent-and record a northward marine transgression from the Xiong'er Rift Basin. Consequently, the central-southern Taihang Mountains served as a critical transition zone connecting the Xiong'er Basin with the Yanliao Basin.

Distinguishing between deep subduction-related magmatism and intracrustal differentiation is critical for reconstructing the tectonic evolution of the North China Craton. In this study, we report zircon U-Pb geochronology, whole-rock geochemistry, Lu-Hf isotopes, and phase equilibrium modeling results for newly identified Mesoarchean TTG gneisses in the Laiyang area of the Jiaobei Terrane. Zircon U-Pb dating constrains two magmatic pulses at ca. 3.0 Ga (Xiabujia and Jiaojiadian trondhjemitic gneisses) and ca. 2.86 Ga (Beizhanggezhuang tonalitic gneisses). Isotopic and geochemical constraints indicate that these rocks originated from the partial melting of ca. 3.2 Ga juvenile mafic crust at low-to-medium pressures. Although the suite is predominantly of low-to-medium pressure affinity, sporadic samples exhibit high Sr/Y ratios and positive Eu anomalies resembling high-pressure TTGs. Phase equilibrium modeling indicates that these "high-pressure" signatures are not indicators of deep eclogite-facies melting, but are artifacts resulting from plagioclase accumulation at shallower depths. We prefer a predominantly vertical tectonic model involving the reworking of a thickened oceanic plateau, possibly facilitated by enhanced mantle heat input.

Neoarchean tonalite-trondhjemite-granodiorite (TTG) gneisses are extensively distributed in the central North China Craton (NCC), recording the early history of continental crust. This study presents six tonalitic gneiss from the Zanhuang Complex, which yield crystallization ages of 2.72-2.69 Ga and metamorphism ages of similar to 2.5 Ga. Two dioritic gneiss gave crystallization ages of 2.72 Ga and 2.69 Ga. One high-Mg dioritic gneiss, with a xenocryst crystallization age of 2.71 Ga, yields an emplacement age of 2.55 Ga. Therefore, the early Neoarchean magmatism is constrained to 2.72-2.69 Ga, underwent metamorphism at similar to 2.5 Ga, and was locally intruded by high-Mg diorites derived from a metasomatized mantle at 2.55 Ga. Moreover, the epsilon(Hf)(t) values (3.91-7.96) and T-DM (c)(Hf) model ages (2.66-2.93 Ga) of the TTGs indicating a juvenile crustal origin formed from the late Mesoarchean to early Neoarchean. All banding-free TTG gneisses exhibit relatively homogeneous tonalitic compositions. They have high SiO2 (66.37-68.13 wt%), Na2O (3.85-4.44 wt%), MgO (1.93-2.09 wt%), Cr (25-33 ppm), Ni (21-26 ppm), and Mg-# values (45-51), low total ferromagnesian elements (6.59-7.28 wt%), Al2O3 (14.67-15.17 wt%), K2O/Na2O (0.27-0.46), and Sr/Y (29-41). These suggest that they are generated from partial melting of low-K basalt under low-preasure (amphibolite-facies) conditions. Banded TTG gneiss exhibit variable compositions that consistent with tonalite or trondhjemite. They are considered to have resulted from the anatexis and mineral segregation of tonalite in the late Neoarchean. Through a comprehensive analysis of similar to 2.7 Ga magmatism in the central NCC, we infer that there may be an magmatic belt through Hengshan, Wutai, Fuping, Zanhuang, Zuoquan, Huixian, Lushan, and Zhongtiao area from north to south. This belt is dominated by TTGs, with minor K-rich granites and mafic rocks. Their Hf-Nd data reveal a pronounced crustal growth and remelting event at similar to 2.7 Ga. These TTGs exhibit significant geochemical heterogeneity, with some units preserving diagnostic subduction-related signatures including high-pressure and mantle metasomatism imprints. We infer that the magmatic belt formed in a subduction-related setting.

Neoarchean lithologies of the North China Craton (NCC) provide essential insights into early continental evolution. This study investigates newly identified dioritic gneisses from the Zanhuang Complex in the central TransNorth China Orogen (TNCO) using zircon U-Pb geochronology, whole-rock geochemistry, and Nd-Hf-O isotopes. The rock types include Luzhuang tholeiitic gabbro-dioritic (2493 +/- 6 Ma) and quartz dioritic (2498 +/- 7 Ma) gneisses, Longmen tholeiitic garnet-bearing dioritic (2493 +/- 6 Ma) and quartz dioritic (2498 +/- 8 Ma) gneisses, and Shicao calc-alkaline dioritic gneisses, which are intruded by 2500 +/- 18 Ma garnet-bearing anatectic granite vein. Geochemical analysis reveals relatively low MgO concentrations and Mg# values, indicating partial melting of mafic rocks. The dioritic gneisses show positive whole-rock epsilon Nd(t) values (+1.9 to + 4.9) and zircon epsilon Hf(t) values (+2.0 to + 10.0), suggesting a mantle-derived origin. Oxygen isotope analysis indicates zircon delta 18O values ranging from 5.9 to 7.7 %o (average 7.0 %o), which are higher than typical mantle zircons, indicating a metasomatized mantle source. Hygrometric calculations show 6.2-6.8 wt% H2O in Luzhuang dioritic gneisses and 12.4-14.5 wt% H2O in Longmen garnet-bearing varieties. The exceptionally high water content in Longmen dioritic gneisses (super-wet magmas) further supports the hypothesis of a subduction-related metasomatic process in the mantle source. These findings provide definitive evidence for Neoarchean subduction processes.

The Zanhuang Complex is situated on the eastern margin of the Trans-North China Orogen, with the Huangcha Pluton being a constituent of this complex. To ascertain the nature of the approximately 2.5-billion-year-old Huangcha Pluton, crucial evidence for understanding its extensional setting was sought through petrogenesis and dating investigations. LA-ICP-MS dating of zircon from the granite yielded an age of (2488 ± 6) Ma. Primarily composed of porphyritic monzonite with sporadic melanocratic enclaves, the Pluton’s phenocrysts are predominantly feldspar with minor quartz. The granite exhibits high SiO2 content (72.64%–74.16%) and alkali levels, with Na2O + K2O ranging from 7.59% to 9.07%, classifying it as a shoshonitic series with a slightly peraluminous feature. Enrichment in large-ion lithophile (LIL) elements (Rb, Th, and U) and depletion in Sr, V, Cr, Co, and Ni were observed, with high Rb/Sr and Ga/Al ratios ranging from 0.73 to 2.72 and 2.75 × 10−4 to 3.11 × 10−4, respectively. The rock exhibits high εNd(t) values, ranging from −0.06 to 0.88, with TDM2 ages falling between 2.79 and 2.87 billion years. Zircon grains display 176Hf/177Hf ratios ranging from 0.281266 to 0.281412 and εHf(t) values spanning from 0.96 to 6.18, calculated using the 207Pb/206Pb age. It is suggested that the Huangcha Pluton represents A-type granite formed via anatexis of the Neoarchean TTG in an extensional setting following orogenic processes. The formation of the Huangcha Pluton further corroborates the stabilization of the North China Craton towards the end of the Neoarchean. This finding supports the hypothesis that the North China Craton may belong to the Rae-family cratons, sharing similar magmatic and tectono-metamorphic records around ~2.5 billion years ago.

从滹沱群底部四集庄组不同的分布区选择了 1件正长花岗斑岩、1件似斑状二长花岗岩砾石及1件侵入于蒋村四集庄组的正长花岗斑岩,进行了锆石U-Pb-Hf同位素分析.获得正长花岗斑岩和似斑状二长花岗岩砾石的锆石207Pb/206Pb加权平均年龄分别为2 507±14 Ma和2 519±35 Ma,推断花岗岩砾石的物源可能为五台新太古代晚期峨口花岗岩和兰芝山花岗岩;侵入于四集庄组的正长花岗斑岩锆石207Pb/206Pb年龄为2 157±15 Ma.结合四集庄组、五台地区高凡群火山岩年龄结果和华北克拉通2.2～2.0 Ga地质事件的性质,认为滹沱群底界可能为2.2～2.18 Ga,顶界时代约为2.0 Ga,其沉积对应一期强烈的陆内裂谷伸展过程.新太古代花岗岩砾石和古元古代花岗岩锆石Hf同位素结果指示,五台地区新太古代早期出现明显的地壳生长,新太古代晚期也存在地壳增长.

华北吕梁地区出露的以陆源碎屑沉积为主的汉高山群为中元古界底界界线层型的理想候选剖面,其时代的确定对认识华北前寒武纪地质演化历史及初始盖层的确定及Nuna超大陆聚散的研究具有重要的意义.目前,汉高山群的时代、划分对比及其意义还存在较大争议.本研究使用SHRIMP(二次离子质谱仪)对汉高山群安山岩中的锆石进行了 U-Pb同位素分析,获得其207Pb/206Pb年龄加权平均值为1 769±9 Ma(2σ).这是首次直接测得汉高山群锆石U-Pb年龄.另测得同一层位的小两岭组3个不同部位火山岩中的锆石207Pb/206Pb年龄加权平均值分别为1 792±18 Ma、1 773±19 Ma和1 778±20 Ma,与汉高山群的年龄在误差范围内一致,故认为汉高山群和小两岭组的时代分别为1 769±9 Ma和1 792～1 773 Ma.结合前人的研究资料,认为汉高山群和小两岭组的形成时代为1 780 Ma左右.吕梁地区汉高山群的剖面地层连续,发育区域上分布较为稳定的安山岩,是华北克拉通中南部极好的区域等时标志层.该时期的裂谷沉积和火山岩在扬子陆块西部、劳伦大陆西北部、澳大利亚北部、南美巴西圣弗兰西斯科(Sao Francisco)克拉通、非洲刚果克拉通及西伯利亚克拉通均有产出,且可以对比,显示同时期由Nuna超大陆初始裂解引起的陆内裂谷沉积地层的全球分布特征,由此提出国际中元古界底界应该下移,并且汉高山剖面可作为国际上新的中元古界底界的候选层型剖面.

有关胶-辽-吉带巨量变沉积岩系时代与物源归属问题一直存在争议.利用LA-MC-ICP MS技术对出露于该带北段通化地区集安群变质表壳岩、片麻状花岗岩、斑状花岗岩和TTG片麻岩样品开展了锆石U-Pb与Lu-Hf同位素分析.结果显示,集安群变质表壳岩碎屑锆石年龄呈现2.5 Ga与2.1 Ga两个明显的主峰,不同类型变质岩中碎屑锆石的年龄分布并不一致.变质程度较低的含墨变粒岩碎屑锆石年龄集中在2.5 Ga左右,反映主要来自新太古代地质体.变质程度较高的夕线石榴堇青片麻岩、透辉片麻岩和大理岩碎屑锆石含量很少,且普遍遭受了变质改造,难以反映真实的物源时代.集安群变质锆石年龄呈现1.95～1.90 Ga、1.90～1.85 Ga和1.85～1.80 Ga 3个阶段,根据定量相图模拟的变质锆石与熔体的产出关系,推断第1阶段年龄代表了变质地体降温初期,第2阶段年龄代表了降温后期大规模熔体冷凝结晶时代,第3阶段则与地体进一步抬升到地壳浅部层次的构造运动有关.集安群变质表壳岩的锆石εHf(t)值介于-12.40～+6.17之间,主峰在-8～-2之间,二阶段模式年龄介于3.0～2.3 Ga之间,并且与太古宙TTG片麻岩和古元古代片麻状花岗岩具有同源演化特点.通化地区太古宙角闪斜长片麻岩(TTG)的侵位年龄为2 574±11 Ma,锆石εHf(t)值介于1.87～7.30之间,二阶段模式年龄介于2.89～2.60 Ga之间,显示为新生地壳部分熔融产物.片麻状花岗岩的侵位年龄为2 104±18 Ma,锆石εHf(t)值介于-2～+2之间,模式年龄介于2.8～2.7 Ga之间,显示为新生地壳与古老表壳岩共同熔融产物.未变形斑状花岗岩的侵位年龄为1 888±8 Ma,锆石eHf(t)值介于-5.43～+0.03,模式年龄介于2.7～2.5 Ga之间,显示主要为古老表壳岩重熔产物.总体来说,胶-辽－吉带早期2.3～2.0 Ga期间呈现典型大陆裂谷发育特征,晚期1.95～1.85 Ga期间呈现碰撞造山带演化特点,二者可能分属不同的构造热事件.

官都岩群是华北克拉通中部造山带赞皇杂岩中重要的变质火山-沉积岩系,经历了高绿片岩相-高角闪岩相变质,准确限定其沉积时代与物质来源对探究中部造山带新太古代-古元古代构造演化过程具有重要意义.利用LA-MC-ICP-MS(多接收激光剥蚀电感耦合等离子质谱仪)与TIMA(矿物自动分析系统)对官都岩群中黑云变粒岩与石英岩进行了锆石矿物包体、U-Pb-Hf同位素与稀土元素原位分析.根据碎屑锆石内部矿物包体组成、阴极发光图像特征与U-Pb年龄结果,认为黑云变粒岩与石英岩中碎屑锆石中最年轻一组的207Pb/206Pb谐和年龄分别为2 544 Ma或2 536 Ma,大致限定了其原岩的最老沉积时代,结合区内黄岔花岗岩岩体侵入官都岩群的野外地质关系,推测官都岩群沉积时代为新太古代末期,并非古元古代.官都岩群黑云变粒岩与石英岩碎屑锆石年龄图谱十分相似,最主要的峰值年龄为2 512 Ma,结合碎屑锆石内部矿物包体与结构特征,认为官都岩群主要物源为新太古代晚期中酸性岩浆岩.两阶段锆石Hf模式年龄揭示2 850～2 700 Ma为赞皇杂岩最强烈的地壳生长阶段.综合本文与中部造山带已发表的数据,认为官都岩群黑云变粒岩与石英岩中变质锆石记录了～2 500 Ma的变质年龄,表明华北克拉通中部造山带普遍遭受了～2 500 Ma变质作用,该期变质作用可能与新太古代晚期华北克拉通初步克拉通化有关.

The Zanhuang Complex, situated on the eastern margin of the central section of the Trans-North China Orogen (TNCO), North China Craton, mainly comprises Archean-Palaeoproterozoic tonalite-trondhjemite-granodiorite (TTG) gneisses, migmatites, granites, metavolcanic rocks, and metasedimentary rocks. Petrographic observations of garnet-bearing pelitic gneisses from the south-eastern Zanhuang Complex show three distinct mineral assemblages (M1-M3) that correspond to three different metamorphic stages. The interpreted prograde metamorphic stage (M1) is mainly represented by the cores of garnet porphyroblasts with fine-grained inclusions of biotite + plagioclase + staurolite + kyanite + quartz + ilmenite. The peak metamorphic stage (M-2) is mainly represented by garnet mantles and a matrix-type mineral assemblage of kyanite + biotite + plagioclase + quartz + ilmenite + melt. The retrograde metamorphic stage (M3) is represented by the presence of sillimanite with garnet rims + biotite + plagioclase + quartz + ilmenite + magnetite. Quantitative phase equilibria modelling constrains the pressure-temperature (P-T) conditions of the M-1 and M-2 stages to 640-670 degrees C/7.3-7.5 kbar and 705-760 degrees C/7.9-9.1 kbar, respectively. The zircons and monazites in the Zanhuang pelitic gneisses all record consistent ages of 1839-1831 Ma, which most likely represent the near-peak metamorphic age. Thus, a clockwise P-T-time (P-T-t) path is determined for the garnet-bearing pelitic gneisses from the Zanhuang Complex. The petrological and geochronological evidence from the pelitic gneisses in the Zanhuang Complex in this paper suggests that the TNCO might have experienced continuous continental collision and rapid tectonic uplift at ca. 1839-1831 Ma, thereby providing a metamorphic constraint on the Palaeoproterozoic tectonic evolution of the TNCO.

Paleoproterozoic (similar to 2.3) Ga metavolcanic rocks occur in the Lengkou area, northern Zhongtiao Mountains of the North China Craton (NCC). The area is dominated by metabasic volcanic rocks, intercalated with metamorphosed intermediate to acid volcanic rocks. The Lengkou metavolcanic rocks have a magmatic zircon U-Pb age of 2317 +/- 13 Ma, but also contain some 2508 Ma inherited zircons. The Lengkou metabasic and intermediate volcanic rocks are calc-alkaline with high SiO2 and K2O contents. They display fractionation of the HREE relative to the LREE, relative enrichments in large ion lithophile elements and depletion in high field strength elements resulting in negative Nb-Ta-Ti and Zr-Hf anomalies. Therefore, they are inferred to have formed in a volcanic arc setting. The meta-acid volcanic rocks of the Lengkou series have geochemical features similar to the surrounding Sushui Complex (Neoarchaean tonalitic gneiss), resulting from partial melting of ancient crust. The Lengkou metabasic volcanic rocks have a low Nd-143/Nd-144 ratio and epsilon(Nd)(t) value of 0.8-1.5, with T-DM of 2.57-2.63 Ga, indicating the mantle-derived mafic rocks were variably contaminated by older continental material. The integrated data from the Lengkou metavolcanic rocks indicate a convergent subduction-related regime in the early Paleoproterozoic. The isotopic signatures and the xenocrystic zircons demonstrate that subduction occurred at a margin of continental crust, rather than within intra-ocean, exploring an Andean-like setting in the NCC at that time.

在全球岩浆活动静寂期,人们在华北克拉通内相继识别出大量～2.3 Ga的地质体,对探讨华北克拉通古元古代地质演化过程具有十分重要的意义.选择中条山地区横岭关二长花岗岩进行了地球化学、锆石U?Pb年代学和Hf同位素研究.横岭关二长花岗岩LA-ICPMS锆石U?Pb年龄结果为2308±12 Ma,代表岩体的形成时代.横岭关二长花岗岩高硅、高钾、高铝、富碱,贫钙、低钠和低钛,A/CNK主要集中在1.0～1.1之间,为高钾钙碱性偏铝-过铝质花岗岩系列.岩石的稀土元素含量相对高,轻重稀土元素分异强烈,并具有明显的Eu负异常.高场强元素Nb、Ta、Zr、Hf、U和大离子亲石元素Rb等相对富集,亏损V、Cr、Co、Ni等相容元素,具有I型花岗岩的特征.横岭关二长花岗岩锆石εHf(t)为0.52～6.24,平均值为2.06,单阶段和两阶段模式年龄分别为2419～2642 Ma和2438～2738 Ma.横岭关二长花岗岩具有同碰撞花岗岩的特征,推测来源于～2.5 Ga古老地壳岩石在挤压碰撞环境下的部分熔融,揭示了华北克拉通在古元古代全球岩浆静寂期并不静寂.

华北克拉通中部阜平地区的阜平岩群是该区分布较广的太古宙地层,经历了角闪岩相-麻粒岩相变质,其时代限定对研究阜平杂岩的早期演化过程具有重要意义.本文利用LA-MC-ICP-MS(多接收激光剥蚀电感耦合等离子体质谱仪)对阜平岩群元坊岩组中的浅粒岩进行了锆石U-Pb-Hf同位素原位分析,获得两期变质锆石年龄分别为2 531±15 Ma和1 943±16 Ma,并根据碎屑锆石内部结构特征和年龄结果,认为核部年龄在2 549～2 500 Ma的碎屑锆石中最大207Pb/206Pb年龄2 549±4 Ma可以代表原岩的最大沉积年龄,初步限定元坊岩组浅粒岩原岩沉积时代为2 550～2 530 Ma.锆石Lu-Hf同位素结果中,176 Lu/177 Hf值为0.000 289 ～0.004 262,176 Hf/177 Hf值为0.281 255～0.281 791.176 Hf/177 Hfi值为0.281 230～0.281 623,εHf(t)值为-5.86～13.62,变化范围较大.单阶段和两阶段模式年龄分别为2 748 ～2 242 Ma和2 810～2 272 Ma.根据锆石U-Pb年龄和Hf同位素结果,提出元坊岩组浅粒岩物源区主要来自新太古代TTG质片麻岩,2.8～2.6 Ga为阜平地区强烈的地壳生长阶段,阜平地区2.5 Ga和1.95 Ga变质信息分别代表华北初步克拉通化和最终克拉通化过程中的变质作用.

太古宙末期钾质花岗岩的广泛发育是陆壳成熟和稳定化的重要标志,对了解早期陆壳的形成与演化具有重要的意义.发育于华北克拉通南缘中条山地区涑水杂岩中的烟庄正长花岗岩的形成年龄和成因还没有被很好地限定,构造背景还存在争议.对烟庄花岗岩进行了锆石U?Pb年代学和Hf同位素以及全岩地球化学和Nd同位素研究.烟庄花岗岩锆石SHRIMP U?Pb年龄为2515±7 Ma.岩石具有高硅(SiO2=73.05％～74.85％)、高钾(K2O=4.46％～5.86％)、富碱(ALK=8.32％～9.36％)、贫钙(CaO=0.55％～0.98％)、低TFeO*(0.73％～1.28％)和MgO(0.31％～0.52％)的特征,A/CNK=1.01～1.04,为弱过铝质的钾玄系列.稀土总量变化较大(ΣREE=63.80×10-6～250.02×10-6)),轻重稀土元素分异明显((La/Yb)N=25.44～92.87),Eu异常变化较大(Eu/Eu*=0.47～0.79).岩石低Sr、Ba,富集Rb、Th、U等元素,亏损Nb、Zr、Y、Yb、Cr、Co、Ni等元素,具有较高的Rb/Sr、Rb/Ba和Sr/Yb比值以及较低Sm/Nd和Nd/Th比值,具有高分异I型花岗岩的特征.烟庄花岗岩具有0附近的全岩εNd(t)值,岩浆锆石具有正的εHf(t)值(2.85～3.66),两阶段Hf模式年龄为2258～2883 Ma,多数在2600～2883 Ma之间.结合其他方面研究,烟庄花岗岩具有同碰撞和后碰撞花岗岩的特征,推测为新生地壳在由挤压向伸展转换的构造背景下部分熔融所形成,可能有少量地幔物质添加.这期钾质花岗岩的形成,标志着华北克拉通太古宙末期强烈岩浆活动的结束以及稳定陆壳的形成.

Mid-Paleoproterozoic (2.2-2.0 Ga) magmatism in the Trans-North China Orogen (TNCO) is of great significance for the Paleoproterozoic geological evolution of the entire North China Craton (NCC). In this paper, we present geochemical, SHRIMP zircon U-Pb and Hf isotopic data on the 2.1-2.0 Ga granitoids in the Fuping Complex of the TNCO. These include the Nanying granitic gneiss, which yielded ages of 2075 +/- 13 Ma, 2079 +/- 9 Ma and 2073 +/- 10 Ma, the Gangnan granitic gneiss, dated at 2081 +/- 8 Ma, 2082 +/- 14 Ma and 2063 +/- 7 Ma, the Baiyangling granite with ages of 2077 +/- 6 Ma, 2070 +/- 19 Ma and 2069 +/- 12 Ma, and the Shangzhuang granite, which yielded ages of 2072 +/- 12 Ma and 2070 +/- 12 Ma. The 2.1-2.0 Ga granitic rocks in Fuping Complex are enriched in SiO2, K2O + Na2O, rare earth elements (REEs) (except Eu), high field strength elements like Zr, Nb, Ga and Y, and depleted in CaO, Al2O3 and Sr. Their Ga/Al ratios and absolute Zr + Nb + Y + Ce contents are high and their average Zr saturation temperatures are as high as 890 degrees C, all of which are consistent with the features of A-type granite. The epsilon(Hf)(t) values of zircon in all samples are much lower than that of the depleted mantle at the same stage, while Hf model T-DM1, T-DM(C) ages have ranges of 2.3-2.7 Ga and 2.4-2.9 Ga, respectively, which are much older than the age of the granitoids. These zircon Hf model ages are similar to those of the Neoarchean TTG (Tonalite-Trondhjemite-Granodiorite) gneisses in the Fuping Complex. Therefore, based on a combination of petrology, geochemistry and isotopic characteristics, we infer that these four 2.1-2.0 Ga granitic plutons in the Fuping Complex are partial melts of the Neoarchean TTG gneiss generated in an extensional environment. Based on extensive data, the 2.1-2.0 Ga A-type granites and the mafic dikes in the Fuping Complex represent a bimodal magma association. Considering the sedimentary rocks of the Gantaohe Group, deposited in the same period, we deduce that the 2.1-2.0 Ga A-type granite in the TNCO Fuping Complex was emplaced in an intra-continental rift setting in the NCC. This evidence indicates that the North China Craton was initially stabilized at the end of the Neoarchean.

本文收集了阜平杂岩新太古代早期?古元古代晚期基底岩石的岩石地球化学、锆石U?Pb年代学、同位素地球化学和变质作用资料,以期对阜平杂岩早寒武纪演化历史进行初步总结.阜平新太古代早期～2.7 Ga片麻岩原岩为英云闪长岩,具有TTG质片麻岩的地球化学特征;其锆石εHf(t)具有较高的正值(+5.44～+7.50),单阶段模式年龄为2745～2824 Ma,表明新太古代早期为阜平杂岩强烈的地壳生长时期.新太古代晚期片麻岩的时代集中于2543～2484 Ma,主要岩石类型为英云闪长岩?奥长花岗岩?花岗闪长岩(TTG),同时区域内还存在二长花岗岩.TTG质片麻岩的εNd(t)值为?1.64～+0.96,单阶段模式年龄为2.76～3.04 Ga;锆石εHf(t)值为?1.9～+7.91,单阶段和两阶段模式年龄分别为2546～2888 Ma和2548～3119 Ma.这些TTG岩石主要为新太古代早期岩石的部分熔融,并有少量中太古代地壳物质参与.近于同期具有岛弧性质的辉长岩和变质作用暗示阜平杂岩新太古代晚期可能经历了俯冲和弧?陆或陆?陆碰撞.古元古代中期(2.1～2.0 Ga)阜平地区花岗质岩浆活动强烈.该阶段花岗岩具有A型花岗岩特征,与同期的火山?沉积岩系形成于华北克拉通古元古代中期伸展的陆内裂谷环境中.阜平杂岩中基性麻粒岩包体记录的变质作用时代为1.89～1.85 Ga,并具有顺时针演化的P?T轨迹,其代表了古元古代晚期裂谷闭合的陆内造山过程,表明华北最终克拉通化.

The Zanhuang Complex is located in central section of the Trans-North China Orogen (TNCO) in the North China Craton (NCC) with complicated tectonic history. The formation timing (Neoarchean or Paleoproterozoic) of the Guandu Group or Central Zanhuang Domain (CZD) is still under debate, while this question is critical for understanding the tectonic evolution of the Zanhuang Complex and the TNCO. The mafic rocks in the Guandu Group (or CZD) can be subdivided into three different types by petrological, geochronological, structural and petrogenetic differences. Type 1 consists of "pillow" epidosites and amphibolites, located at the west part of the Guandu Group; type 2 dominated by amphibolites and interbedding with various sedimentary rocks, located at the east part; and type 3 consists of mafic dikes beyond the scope of this paper. Type 1 mafic rock yielded zircon U-Pb age of 2501 +/- 12 Ma which constrains it formed at Neoarchean with older Nd Tom ages (2.8-3.0 Ga). Interbedded sedimentary rocks with younger than 2.1 Ga detrital zircon ages, and the much younger Nd T-DM model ages (2.2-2.3 Ga) of the amphibolites from type 2, together suggest that the type 2 mafic rocks and associated sedimentary rocks may have formed at Paleoproterozoic. Thus, we propose that the so-called Guandu Group is not a single and unitary tectonic-lithological unit but consists of at least two different volcanic-sedimentary successions formed at different times and pieced together by later tectonic event (s). A new two-period tectonic events model is proposed here. Before 2.5 Ga, the western margin of the Eastern Block deposited a series of volcanic-sedimentary rocks (type 1). At similar to 2.5 Ga, the Fuping arc (including the Western Zanhuang Domain) amalgamated with the Eastern Block by arc-continent collision. After a quiescent period, it underwent similar to 2.1 Ga extension and rifting. Later, the rift evolved into a small ocean basin with the deposition of volcanic-sedimentary sequences (type 2), then closed through west-dipping subduction and collision at 1.9-1.85 Ga, resulting in the final amalgamation of the NCC and the widespread deformation and metamorphism in the Zanhuang Complex as well as the whole TNCO.

The late Archaean witnessed a critical transition of the composition of the continental crust from predominantly sodic tonalite‐trondhjemite‐granodiorites (TTGs) to a combination of TTGs and increasing proportion of potassic calc‐alkaline granitoids. This shift is also well recorded in the Zanhuang Complex located in the central part of the North China Craton (NCC). In this work, we present a detailed geochemical study of these granitoids and subdivide them into four groups, that is, TTGs, sanukitoids, crustal‐sourced granitoids, and hybrid granitoids. The TTGs in the Zanhuang Complex may have formed at a longer and earlier period during ~2.7 to ~2.5 Ga as the first stage. They show typical TTG characteristics, such as high SiO2, Na2O, and Sr/Y and depletion of Nb, Ta, Ti, and HREE. The TTGs are interpreted to have formed in a subduction‐related environment. The other three groups of granitoids formed at a shorter and later stage. The sanukitoid sample shows high MgO and Mg# and other geochemical signatures of typical Archaean sanukitoid affinity, yielding a weighted mean zircon 207Pb/206Pb age of 2,517 ± 5 Ma as the crystallization age. The sanukitoid magma derived from partial melting of a hydrous mantle peridotite source metasomatized by slab‐derived melts or fluids. The crustal‐sourced granitoids, including a new sample (~2,510 Ma) in this work, the Jiandeng granite (~2,490 Ma), and the Huangcha/Wangjiazhuang granite (2,488 to 2,517 Ma) show signatures of a mainly crustal source such as high SiO2 and K2O, low MgO and Mg# values, and weakly peraluminous. The hybrid granitoids represented by the Haozhuang granitoid (2,511 to 2,528 Ma) are characterized by enrichment in both incompatible (LILE and LREE) and compatible (Mg, Ni, and Cr) elements and may have formed by mixing/contamination of multiple magmas or sources. The temporal and spatial distributions of these groups of granitoids indicate that the Zanhuang Complex experienced a subduction–collision event between the Fuping arc and the Eastern Block of the NCC at the end of Archaean.