The ~1.9 Ga syn-collisional granitic magmatism in the Sushui Complex: new evidence for the late Paleoproterozoic tectonic evolution of the southern North China Craton

Mineral chemistry, trace elements and Sr–Nd–Hf isotope geochemistry and petrogenesis of Cailing and Furong granites and mafic enclaves from the Qitianling batholith in the Shi-Hang zone, South China

ABSTRACTThis article reports systematic zircon U–Pb dating, whole-rock geochemistry, and Sr–Nd isotopic data for the Early Cretaceous Jialou granitoids along the southernmost margin of the North China Craton (NCC), adjacent to the Tongbai Orogen. These results will provide significant constrains on the crustal evolution of the southern margin of the NCC. Zircon U–Pb analyses, using laser ablation–multicollector–inductively coupled plasma–mass spectrometry, indicate that the Jialou granitoids were emplaced at ~130 Ma. The granitoids have high SiO2, K2O, Al2O3, Sr, and Ba contents, high Sr/Y and (La/Yb)N ratios, and low concentrations of MgO, Y, and heavy rare earth elements, indicating a low-Mg adakitic affinity. They have relatively high initial 87Sr/86Sr ratios (0.707464–0.708190) and negative εNd(t) values (–11.8 to –15.2), similar to those of the Palaeoproterozoic lower crust in the NCC. These geochemical and isotopic features indicate that the Jialou low-Mg adakitic rocks were derived by partial melting of mafic Palaeoproterozoic lower crust of the NCC at >50 km depth, leaving behind a garnet amphibolite residue. The petrogenesis of the Jialou low-Mg adakitic rocks, plus the petrogenesis of Mesozoic granitoids and lower crustal xenoliths entrained in the Late Jurassic Xinyang volcaniclastic diatreme, suggests that the continental crust along the southern margin of the NCC was thickened during the Middle Jurassic to Early Cretaceous, but thinned after 130 Ma. We propose that crustal thickening was caused by a late Middle Jurassic to Early Cretaceous intra-continental orogeny, rather than continent–continent collision between the NCC and the Yangtze Craton. We also suggest that crustal thinning and Early Cretaceous magmatism were related to subduction of the palaeo-Pacific plate, rather than post-orogenic collapse of the Qinling–Tongbai–Dabie Orogen.

Abstract: In this paper we report geochemical and Nd‐Sr isotopic data for a late Archean gneissic granitic pluton (Hengling pluton), an early Paleoproterozoic complex (Xipan complex) and a late Paleoproterozoic granitic pluton (Yunzhongshan granites) from the Lüliang‐Wutai terrain, North China, to trace the source of these late Archean‐Paleoproterozoic granitoids and, particularly, to understand the nature and mechanism of continental growth at that time. The Hengling granitic gneisses (ca. 2.51 Ga) are characterized by high Na2O and LILEs, TTG‐like REE patterns (highly depleted HREE and minor Eu anomalies) and moderately depleted Nd‐Sr isotopic compositions (∍Nd(t) =1.2‐2.7, ISr=0.7015‐0.7019), and were considered as being products of arc magmatism that was developed upon the North China craton. The Xipan complex (ca. 2.2 Ga) contain gabbroic diorite and monzonite, mostly being Na2O‐rich, highly fractionated REE patterns and isotopically enriched (∍Nd(t) =−1.5 to −4.1, ISr=0.7038‐0.706). The gabbroic diorites probably originated from melting of an enriched mantle source, but significantly contaminated by lower crustal material, and the monzonites probably represent a product of a mixture between the gabbroic dioritic magma and granitic melts of crustal origin. The Yunzhongshan post‐collisional granitoids (ca. 1.8 Ga) are characterized by high‐K affinity and highly‐enriched and homogeneous Nd isotopic compositions (∍Nd(t) = −4.9 to −5.7), although they split into two groups in terms of REE patterns: one group showing elevated HREE (and Sc, Y and Zr) with significant negative Eu anomalies and the other showing highly depleted HREE and, to a lesser extent, mid‐REE with negligible Eu anomalies. These granites are genetically related to a process of extensional collapse of a thickened orogen. They formed through magma mixing between mantle‐derived basaltic magmas and crust‐derived granitic melts, followed by significant fractionation of ferromagnesian phases (like hornblende and Cpx) and feldspar and accessory zircons. Some Yunzhongshan granites show very old Nd model ages (2.9‐3.0 Ga), suggesting the existence of continental crust older than 2.7 Ga, which is supported by our zircon Hf isotopic data for these granites.

Petrology and geochemistry of charnockites (felsic ortho-granulites) from the Kerala Khondalite Belt, Southern India: Evidence for intra-crustal melting, magmatic differentiation and episodic crustal growth

Recycling of continental crust in the southern North China Craton: Constraints from the Sr–Nd–Pb–Hf–O isotopic compositions of Early Cretaceous Funiushan granites

Paleoproterozoic (1.96–1.86 Ga) granites in Xinyang record zoned deep crustal structure and multi-stage reworking beneath the southern North China Craton

Within the high-grade metamorphic basement, the central portion of North China Craton (NCC), a group of Neoarchean khondalites (KS) is identified. They are characterized by large ion lithophile elements (LILE) enrichment, lower abundances of Zr, Hf and Sr. Their rare earth element (REE) distribution has significant LREE enrichment and negative Eu anomalies. The protoliths of KS are interpreted as feldspathic quartzite, shale or pelite and carbonite, deposited in a shallow sea upon cratonic shelf distant from the land. KS’s source region might be dominated by granitic rocks, with a minor amount of TTG, underwent comparatively severe chemical weathering. Considering relevent tectonic constraints, we suggest that khondalites from central portion of NCC, an important metamophosed sedimentary cover, are the most significant exogenetic marker of Neoarchean continental cratonization for NCC.

The Morro do Coco granite (MC) is a post-collisional intrusive body that was emplaced at Ribeira Belt, in the Cambro-Ordovician, succeeding the final stages of the Gondwana supercontinent amalgamation. This unit requires more studies, contrasting with similar best investigated occurrences of the central Ribeira Belt. This work presents a detailed investigation of such unit using petrography, Inductively Coupled Plasma (ICP), X-Ray Fluorescence (XRF) whole-rock geochemistry, U-Pb (SHRIMP) geochronology and Sm-Nd isotopes. The rock is a nearly undeformed syenogranite, geochemically classified as a high-K calc-alkaline magnesian, with metaluminous to slightly peraluminous affinity. Strongly light rare earth elements (LREE)-enriched patterns with significant negative Eu anomalies, typical of post-collisional granites, are identified. Similarly to other post-collisional granites of the central Ribeira Belt, U-Pb zircon data provide crystallization age of 496 ± 3 Ma . Sm-Nd isotopic data suggest crustal magma source as indicated by eNd(496) of -9, 143Nd/144Nd ratios between 0.511747 and 0.511752 and Mesoproterozoic TDM ages of 1.3 Ga. Based on its geochemical characteristics, morphology and geochronology, this unit is considered here as a member of Nova Friburgo Suite. Geochronological data defined three pulses of magmatism in this part of the orogen during the Cambro-Ordovician (515, 490 and 460 Ma).

Early Paleozoic granitic magmatism and mineralization in the Debao Sn-Cu deposit, South China: Constraints from zircon and cassiterite U-Pb geochronology and whole-rock geochemistry

Late Neoarchean to Paleoproterozoic arc magmatism in the Shandong Peninsula, North China Craton and its tectonic implications

Ion-adsorption-type rare-earth element (iREE) deposits, a primary source of global heavy REE (HREE) ores, have attracted wide attention worldwide due to their concentrated distributions and irreplaceable role in the field of cutting-edge technologies. In recent years, iREE mineralization has been reported in the overlying weathering crust of the Mosuoying granites within the Dechang counties, Sichuan Province, Southwest China, suggesting great potential for the formation of iREE deposits. The Mosuoying granites, acting as the primary carrier of REE pre-enrichment, govern the contents and distribution patterns of REEs in their weathering crust. Therefore, investigating the sources and enrichment mechanisms of REEs in the parent rocks will provide a critical theoretical basis for the scientific exploitation and utilization of iREE deposits. In this study, we investigated the migration and enrichment of REEs in the Mosuoying granites (850–832 Ma) using petrography, geochronology, geochemical, and Sr-Nd-Hf isotopic data. The results reveal that the REE enrichment in the Mosuoying granites might be associated with both the melting of crustal felsic rocks and the magmatic-hydrothermal evolution. On the one hand, the granites exhibit different REE patterns. Compared to the light REE (LREE)-rich granites, the HREE-rich granites feature higher SiO2 contents, higher differentiation index (DI), lower Nb/Ta and Zr/Hf ratios, and more significant negative Eu anomalies, indicating that the crystal fractionation of magmas governed the differentiation of REEs. Furthermore, the hydrothermal fluids further promoted the formation of the HREE-rich granites. On the other hand, the geochemical characteristics suggest that they are A-type granites. Regarding the isotopic characteristics, the Mosuoying granites exhibit negative whole-rock εNd(t) and zircon εHf(t) values, suggesting an evolved crustal source. Therefore, we suggest that the high REE contents in the Mosuoying A-type granites might originate from the partial melting of felsic rocks in a shallow crustal source under high-temperature and low-pressure conditions. Specifically, the high-temperature A-type granitic magmas caused the partial melting of the felsic crustal materials to release REEs; concurrently, these magmas enhanced the solubility of REEs in melt during magmatic evolution, inhibiting the separation of REE-bearing minerals from the melts. These increased the REE contents of the granites. The high-temperature heat source might be associated with the process where the asthenospheric mantle experienced upwelling along slab windows and heated continental crust in the Neoproterozoic extensional setting.

The North China Craton (NCC) was stable for more than 2.0 Gyr before a Jurassic–Cretaceous large-scale lithospheric thinning event, but the geodynamic setting during the early phases (Late Jurassic) of NCC reworking remains controversial. We present new petrological and whole-rock geochemical data, zircon and apatite geochemistry, U–Pb ages, O isotopic data, and Sr–Nd isotopic data for two phases of Late Jurassic granite (Linglong and Luanjiahe) from the Jiaobei terrane, southeastern NCC. LA-ICP-MS zircon U-Pb dating suggests that the Linglong granite formed about 6 Myr earlier than Luanjiahe granite (158 Ma vs 152 Ma), after the inception of the paleo-Pacific plate subduction. High zircon U/Yb ratios, high δ18O values [7.89 ± 0.10‰ to 7.67 ± 0.14‰ (2σ)], and inherited zircon age spectra, as well as high apatite F/Cl ratios and Sr–Nd isotopic compositions, suggest that the Linglong and Luanjiahe granites formed by partial melting of ancient thickened lower continental crust of the NCC and Yangtze Craton. Magma evolution modelling based on Rb and Rb/Nb data suggests a similar decoupled assimilation-fractional crystallization process for the generation of Linglong and Luanjiahe granite but with different assimilation degrees. The water contents of parental magma evaluated by using whole-rock Ba, Sr and apatite F, Cl data indicate that the Linglong granite was formed in a relatively water-rich environment than Luanjiahe. This is consistent with the presence of amphibole and minor negative Eu anomalies in the Linglong granite, as water input can promote amphibole fractionation and suppresses plagioclase crystallization. Considering the similar magma sources but distinct water contents of the granites, and the oblique Paleo-Pacific plate subduction setting in the Late Jurassic, the fluids were likely released from the ocean plate beneath a stacked thickened crust. Since the earliest mafic dikes (OIB-type) in the NCC are coeval with the Luanjiahe granite, we suggest that the lower water contents of the Luanjiahe granite were associated with roll-back that resulted in an increasing distance from slab to continental crust. Such a tectonic transition from subduction compression (158 Ma) to initial extension (152 Ma) in the Late Jurassic perhaps possibly marks the beginning of the reworking of the NCC.

Cenozoic intraplate basalts in eastern China show variations of Pb, Sr, and Nd isotope ratios that essentially correspond to major lithospheric domains with distinct tectonic histories. Whereas an enriched‐mantle EM1‐type isotope signature is commonly observed in basalts from the North China block, an EM2‐type isotope signature appears to dominate in those from the South China block. This study reports new trace element data for Cenozoic basalts occurring around the Tanlu fault zone, a sinistral, translithospheric fault related to the Triassic continental collision between the North and South China blocks. Combining published isotope data, basalts from the Subei basin in the east of the Tanlu fault exhibit the EM1‐type geochemical and isotopic features, implying that their lithospheric mantle source region is structurally affiliated with the North China block. This is consistent with the crustal detachment collision model that suggests a subsurface suture between the North and South China blocks ...

Numerous questions regarding the formation and evolution of Earth’s early continental crust remain unresolved. Ancient rocks are essential to understanding these early geological processes. This study provides new geochronology, geochemistry, and zircon Hf-O isotope data from recently discovered Eoarchean granitoids in the Anshan area of the North China Craton (NCC). Zircon U-Pb dating indicates that these granitoids formed at ca. 3.8 Ga and include both trondhjemitic and monzogranitic gneisses. The trondhjemitic gneisses are characterized by high SiO2 and Na2O contents, low magnesium number (Mg#), low Sr/Y and (La/Yb)N ratios, and slightly negative Eu anomalies. These rocks exhibit enrichment in light rare earth elements (LREE) with flat heavy rare earth element (HREE) patterns. Their zircon εHf(t) values range from −3.34 to + 1.09, with two-stage model ages (TDM 2) between 4.43 and 3.99 Ga. The magmatic zircons show δ18O values of + 5.33‰ – +6.98‰. These geochemical and Hf-O isotope features suggest that the trondhjemitic gneisses, classified as low-pressure type, likely formed through the partial melting of Hadean to early Eoarchean mafic proto-crust under upper-amphibolite facies conditions. In comparison, the monzogranitic gneisses display higher SiO2 and K2O levels, lower Sr/Y, (La/Yb)N, and (Gd/Yb)N ratios, and more pronounced negative Eu anomalies. These monzogranitic gneisses are enriched in Rb, Th, and U and depleted in Ba, Sr, Nb, P and Ti. Such geochemical traits classify them as highly differentiated granites. Zircon Hf isotope data reveal radiogenic values, with TDM 2 ages between 4.23 and 4.01 Ga and εHf(t) values ranging from −1.60 to + 0.85. These evidences suggest that the monzogranitic gneisses were derived from the partial melting of ancient felsic source and underwent fractional crystallization during the late stages of magma evolution. The diversity of the ca. 3.8 Ga granitoids indicates the presence of a highly evolved continental crust in the NCC during the early Eoarchean. Hf isotope data show that the earliest crust grew primarily through the partial melting of juvenile crust derived from a depleted mantle, accompanied by certain reworking or recycling of pre-existing continental material. The ca. 3.8 Ga trondhjemitic and monzogranitic gneisses likely formed in an extension environment, such as intraplate rifting setting. Continental crust evolution in the NCC during early Eoarchean was primarily driven by magma underplating associated with asthenospheric mantle upwelling, potentially linked to mantle plume activity.

The Late Precambrian Wufoshan Group from the southern North China Craton (NCC) is significant for its contribution to our understanding of the Precambrian evolution of the NCC, which consists of the Lower Ma'anshan, Upper Ma'anshan, Puyu, Luotuopan, and Hejiazhai formations. Detrital zircon U–Pb ages and Lu–Hf isotopes from the Puyu, Luotuopan, and Hejiazhai formations are used in this study to constrain the depositional age and provenance of the Wufoshan Group and crustal evolution of the NCC. The Puyu Formation is characterized by detrital zircon U–Pb age populations of ~2.13 Ga and ~2.50 Ga, similar to the Lower–Upper Ma'anshan formations from the literature. The Luotuopan Formation exhibits age populations of 1.85–2.18 Ga and 2.28–2.98 Ga, with mainly negative εHf(t) values and scattered positive εHf(t) values clustering at two groups of 2.48–2.52 Ga and 2.64–2.97 Ga. The Hejiazhai Formation displays age populations of 0.98–2.00 Ga and 2.51–2.79 Ga with mainly positive εHf(t) values, whose depositional age is constrained as Neoproterozoic era by the youngest graphical detrital zircon age of 976 ± 20 Ma. Provenance studies indicate that the Mesoproterozoic Lower–Upper Ma'anshan and Puyu formations were sourced from the middle Trans‐North China Orogen (TNCO), while the Neoproterozoic Luotuopan and Hejiazhai formations were derived from the southern TNCO and the North Qinling Terrane, respectively. The clastic rock series in the southern NCC is divided into Luotuopan type and Hejiazhai type by detrital zircon U–Pb age pattern and Hf isotopic characteristics, suggesting Late Mesoarchean to Early Palaeoproterozoic (2.47–2.97 Ga) crustal growth in the interior NCC, and Late Palaeoproterozoic to Early Neoproterozoic (0.98–2.08 Ga) crustal growth in the marginal NCC. The crustal evolution of the NCC can be classified into three stages, namely >3.0 Ga continental nuclei generation, the Meso‐Neoarchean massive growth, and the Palaeo‐Mesoproterozoic interior reworking and marginal growth.