Search Results (136)

The Chagai porphyry copper belt is a major component of the Tethyan metallogenic domain, which spans approximately 300 km and hosts several giant porphyry copper deposits. The tectonic setting, whether subduction-related or post-collisional, and the deep dynamic processes governing the formation of these giant deposits remain poorly understood. Mafic microgranular enclaves (MMEs), mafic dikes, and multiple porphyries have been documented in the Saindak mining area. This work examines both the ore-rich and non-ore intrusions in the Saindak porphyry Cu-Au deposit, using methods like molybdenite Re-Os dating, U-Pb zircon ages, Hf isotopes, and bulk-rock geochemical data. Geochronological results indicate that ore-fertile and barren porphyries yield ages of 22.15 ± 0.22 Ma and 22.21 ± 0.33 Ma, respectively. Both MMEs and mafic dikes have zircons with nearly identical ²⁰⁶Pb/²³⁸U weighted mean ages (21.21 ± 0.18 Ma and 21.21 ± 0.16 Ma, respectively), corresponding to the age of the host rock. Geochemical and Sr–Nd–Hf isotopic evidence indicates that the Saindak adakites were generated by the subduction of the Arabian oceanic lithosphere under the Eurasian plate, rather than through continental collision. The adakites were mainly formed by the partial melting of a metasomatized mantle wedge, induced by fluids from the dehydrating subducting slab, with minor input from subducted sediments and later crust–mantle interactions during magma ascent. We conclude that shallow subduction of the Arabian plate during the Oligocene–Miocene may have increased the flow of subducted fluids into the sub-arc mantle source of the Chagai arc. This process may have facilitated the widespread deposition of porphyry copper and copper–gold mineralization in the region. Full article

The El Bola mafic–ultramafic intrusion (EBMU) in Egypt’s Northern Eastern Desert represents an example of Neoproterozoic post-collisional layered mafic–ultramafic magmatism in the Arabian–Nubian Shield (ANS). The intrusion is composed of pyroxenite, olivine gabbro, pyroxene gabbro, pyroxene–hornblende gabbro, and hornblende-gabbro, exhibiting adcumulate to heter-adcumulate textures. Mineralogical and geochemical analyses reveal a coherent trend of fractional crystallization. Compositions of whole rock and minerals indicate a parental magma of ferropicritic affinity, derived from partial melting of a hydrous, metasomatized spinel-bearing mantle source, likely modified by subduction-related fluids. Geothermobarometric calculations yield crystallization temperatures from ~1120 °C to ~800 °C and pressures from ~5.2 to ~3.1 kbar, while oxygen fugacity estimates suggest progressive oxidation (log fO₂ from −17.3 to −15.7) during differentiation. The EBMU displays Light Rare Earth element (LREE) enrichment, trace element patterns marked by Large Ion Lithophile Element (LILE) enrichment, Nb-Ta depletion and high LILE/HFSE (High Field Strength Elements) ratios, suggesting a mantle-derived source that remained largely unaffected by crustal contribution and was metasomatized by slab-derived fluids. Tectonic discrimination modeling suggests that EBMU magmatism was triggered by asthenospheric upwelling and slab break-off. Considering these findings alongside regional geologic features, we propose that the mafic–ultramafic intrusion from the ANS originated in a tectonic transition between subduction and collision (slab break-off) following the assembly of Gondwana. Full article

The tectonic evolution of the Paleo-Pacific Ocean and the destruction mechanism of the North China Craton (NCC) are still controversial. In this study, we conducted zircon U-Pb dating, whole-rock geochemistry, and Sr-Nd-Hf isotope analyses on the Weiyuanpu mafic–ultramafic intrusions in the eastern segment of the northern margin of the NCC to discuss their petrogenesis and tectonic implications. The Weiyuanpu mafic–ultramafic intrusions consist of troctolite, hornblendite, hornblende gabbro, gabbro, and minor diorite, anorthosite, characterized by cumulate structure. The main crystallization sequence of minerals is olivine → pyroxene → magnetite → hornblende. The zircon U-Pb ages of hornblendite, hornblende grabbro, and diorite are ~170Ma. Geochemical characteristics exhibit low-K tholeiitic to calc-alkaline series, enriched in light rare-earth elements (LREE) and significant large-ion lithophile elements (LILE), and depleted in high-field-strength elements (HFSE). Sr-Nd isotopic compositions are I_Sr = 0.7043–0.7055, εNd(t) = −0.7 to +0.9, and zircon εHf (t) values range from +3.4 to +8.7. These results suggest that the source region was a phlogopite-bearing garnet lherzolite mantle metasomatized by subduction fluids. The study reveals that the northeastern margin of the NCC was in a back-arc extensional setting due to the subduction of the Paleo-Pacific Ocean during the Middle Jurassic, which caused lithosphere thinning and mantle melting in this region. Full article

Continental rifting is the process by which land masses separate and create new ocean basins. The emplacement of large igneous provinces (LIPs) is thought to have played a key role in (super) continental rifting; however, this relationship remains controversial due to the lack of a clearly established mechanism linking LIP emplacement to continental fragmentation. Here, we show that plume flow links LIP magmatism to continental rifting quantitatively. Our findings are further supported by the sedimentary record, as well as by the mineralogy and petrology of the rocks. This study analyzes the early Cretaceous separation of West Gondwana into South America and Africa. Prior to rifting, Jurassic hiatuses in the stratigraphic record of continental sediments from both continents indicate plume ascent and the resulting dynamic topography. Cretaceous mafic dyke swarms and sill intrusions are products of major magmatic events that coincided with continental rifting, leading to the formation of large igneous provinces in South America and Africa, including the Central Atlantic Magmatic Province, Equatorial Magmatic Province, Paraná–Etendeka, and Karoo. It has been suggested that dyke intrusions may weaken the lithosphere by reducing its mechanical strength, creating structural weaknesses that localize extensional deformation and facilitate rift initiation. The sedimentary analysis and petrological evidence from flood basalt magmas indicate that plumes may have migrated from the depths toward the surface during the Jurassic and erupted during the Cretaceous. It is thought that the resulting fast plume flow, induced by one or more mantle plumes, generated a dynamic force that, in combination with lithospheric weakening from dyke intrusion, eventually rifted the lithosphere of West Gondwana. Full article

Numerous mineral microinclusions discovered in the Triassic Ildeus mafic–ultramafic intrusion are dominated by base metal sulfides, gold, silver, and their alloys, as well as rare earth element (REE) minerals. These mineral microinclusions were formed through both the magmatic differentiation of the Ildeus intrusion and the multi-stage interaction of intrusive rocks with late-magmatic, post-magmatic and post-collisional fluids. A comparison of the results of our microinclusions study with ore mineralization discovered within the Ildeus intrusion suggests that microinclusion assemblages in igneous rocks are, in some cases, precursors of potentially economic mineralization. In the case of the Ildeus rocks, sulfide microinclusions correspond to potentially economic disseminated nickel–cobalt sulfide ores, while microinclusions of gold and its alloys correlate with intrusion-hosted, erratic gold mineralization. The occurrence of silver and rare earth element minerals in Ildeus plutonic rocks indicates the possible presence of silver and REE mineralization, which is supported by sub-economic whole-rock silver and REE grades in parts of the Ildeus intrusion. The results of our investigation suggest that studies of mineral microinclusions in magmatic rocks may be useful in the evaluation of their metallogenic specialization and ore-forming potential and could possibly be utilized as an additional prospecting tool in the regional exploration for precious, base, and rare metals. Full article

Late Mesozoic magmatism in Southeast China extensively reworked the Cathaysia Block’s crust, linked to the Paleo-Pacific Plate subduction beneath East Asia. The northeastern Cathaysia Block, largely covered by Cretaceous volcanic-sedimentary basins, has limited Jurassic exposure to Early Cretaceous intrusions, which provides critical insights into deep crust-mantle processes. In this study, we present zircon U-Pb geochronology and Hf isotope, whole-rock geochemistry, and Sr-Nd isotopes of the Middle Jurassic syenite-granite suites and Early Cretaceous granites with enclaves in the Qingyuan area (SW Zhejiang Province) to constrain their petrogenesis and tectonic significance. Middle Jurassic syenites and alkali-feldspar granites (169–167 Ma) exhibit calc-alkaline to shoshonitic affinities and weakly peraluminous compositions. Early Cretaceous granites (134 Ma) and their enclaves (136 Ma) are high-K calc-alkaline and weakly peraluminous to metaluminous. All samples show LILE and LREE enrichment, HFSE depletion, and negative Eu and Sr anomalies, with only syenites displaying negative Ce anomalies. We suggest that the Middle Jurassic syenites originated from the partial melting of an enriched lithospheric mantle influenced by subduction-related metasomatism. Alkali-feldspar granites derived from partial melting of the basement of the Cathaysia Block. Early Cretaceous granites formed by partial melting of lower crustal mafic rocks, with enclaves representing earlier crystallization products, which were then mechanically mixed with granites. We propose the NE Cathaysia Block underwent significant reworking from the Middle Jurassic to the Early Cretaceous. Middle Jurassic syenites formed in a compressional setting linked to Paleo-Pacific Plate subduction, while Early Cretaceous magmatism reflects lithospheric extension and crust-mantle interaction triggered by slab rollback. Full article

Magmatic nickel–copper–platinum group element (PGE) deposits hosted in mafic–ultramafic intrusions within volcanic arc systems are highly attractive targets for mineral exploration, yet their genesis remains poorly understood. This study investigates metagabbroic intrusions in the Paleoproterozoic Lynn Lake greenstone belt of the Trans-Hudson Orogen to identify the key factors, in the original gabbros, that control the formation of magmatic Ni-Cu-PGE deposits in volcanic arc systems. By examining the field relationships, geochemical and sulfur and oxygen stable isotope compositions, mineralogy, and structural fabrics, this study aims to explain why some intrusions host mineralization (e.g., Lynn Lake and Fraser Lake intrusions), whereas others remain barren (e.g., Ralph Lake, Cartwright Lake, and Snake Lake intrusions). Although both the fertile and barren gabbroic, likewise original, intrusions exhibit metaluminous, tholeiitic to calc-alkaline affinity with volcanic arc geochemical signatures, they differ significantly in shape, ranging from vertical and tube-like to tabular forms, reflecting distinct geological settings and magma dynamics. The gabbroic rocks of fertile intrusions exhibit erratic trace element profiles, lower (Nb/Th)_N and higher (Cu/Zr)_N ratios, as well as a larger range of δ³⁴S values than those in barren intrusions. Key factors influencing Ni-Cu-PGE mineralization include the degree of partial melting of the mantle, early sulfide segregation, and crustal contamination, particularly from volcanogenic massive sulfide deposits. These processes likely triggered sulfide saturation in the mafic magmas. Geochemical proxies, such as PGE concentrations and sulfur and oxygen stable isotopes, provide critical insights into these controlling factors. The results of this study enhance our understanding of the metallogenic processes responsible for the formation of magmatic Ni-Cu-PGE deposits in the gabbroic intrusions emplaced in an extensional setting due to slab rollback, during the geological evolution of the Lynn Lake greenstone belt, offering valuable guidance for mineral exploration efforts. Full article

This study explores the generation of natural hydrogen through the serpentinization of onshore ultramafic rocks, highlighting its potential as a clean energy resource. By investigating critical factors such as mineral composition, temperature, and pressure, the research develops an empirical model using multiple regression analysis to predict hydrogen generation rates under varying geological conditions. A novel five-stage volumetric calculation methodology is introduced to estimate hydrogen production from ultramafic rock bodies. The application of this framework to the Giles Complex, an ultramafic-mafic intrusion in Australia, suggests a hydrogen generation potential of approximately 2.24 × 10¹³ kg of hydrogen through partial serpentinization. This estimate is based on the assumed mineral composition, depth, and temperature conditions within the intrusion, which influence the extent of serpentinization reactions. The findings demonstrate the significant potential of ultramafic complexes for natural hydrogen production and provide a foundation for advancing natural hydrogen exploration, refining predictive models, and supporting sustainable energy development. Full article

The widespread occurrence of Mesozoic ocean island basalt (OIB)-like igneous rocks in the Southern Tibetan Himalayan Belt provides important constraints on the rifting of East Gondwana. This study undertook a petrological, geochronological, and geochemical investigation of mafic intrusive rocks in the Cuona area of the eastern Tethyan Himalayan Belt. The mafic intrusions have OIB-type geochemical signatures, including diabase porphyrite, gabbro, and diabase. Zircon U–Pb dating indicates that the diabase porphyrite formed at 135.0 ± 1.6 Ma. The diabase porphyrite and gabbro are enriched in high-field-strength elements (Nb and Ti) and large-ion lithophile elements (Sr and Pb) and experienced negligible lithospheric mantle or crustal contamination. The diabase is enriched in large-ion lithophile elements (LILEs, e.g., La and Ce) and depleted in high-field-strength elements (HFSEs, e.g., Ru, Zr and Ti). In general, the mafic intrusions exhibit significant light REE enrichment and heavy REE depletion and have no Eu anomalies. Whole-rock neodymium (ε_Nd(t) = 1.55) and zircon Hf (ε_Hf(t) = 0.60–3.73) isotopic compositions indicate derivation of the magma from enriched type I mantle. We propose that the diabase porphyrite and diabase formed in a continental margin rift setting, influenced by the Kerguelen mantle plume, and represent magmatism related to the breakup of East Gondwana. However, the gabbro formed in a relatively stable continental intraplate environment, likely derived from deep magmatic processes associated with the Kerguelen mantle plume. Our results provide new constraints on the early activity of the Kerguelen mantle plume and offer insights into the breakup and tectonic evolution of East Gondwana. Full article

Mafic and ultramafic rocks have become a promising approach for atmospheric carbon dioxide (CO₂) reduction, as they are major sources of CO₂-reactive minerals, i.e., olivine, pyroxene, plagioclase, and serpentine. The minerals potentially sequester CO₂ by turning it into a stable solid phase through carbon mineralization in the rock weathering process. However, detailed descriptions and evaluations of the target formations are lacking. This study investigates the mineralogical composition and microtextural characteristics of representative mafic and ultramafic rocks observed in northern Thailand, using a petrographic analysis. The results show that variations in CO₂-reactive mineral assemblages of rocks certainly affect their theoretical CO₂ uptake potential. Ultramafic rocks tend to sequester larger amounts of CO₂ than mafic rocks. The microtextural observation reveals the mineral size ranges of 0.05–5 mm for ultramafic and mafic intrusive rocks and 0.01–2 mm for mafic extrusive and metamorphosed rocks. Reducing the rock size to be equal to the average size of the reactive minerals could be considered one of the practical designs in enhanced rock weathering activities. Understanding the mineralogical and textural characteristics of target rocks thus plays a crucial role in further georesource exploration and engineering designs, supporting climate action strategies on various scales. Full article

The Cambrian period marks a crucial phase in the initial subduction of the Proto-Tethys Ocean beneath the East Kunlun Orogen. Studying the I-type granites and mafic–ultramafic rocks formed during this period can provide valuable insights into the early Paleozoic tectonic evolution of the region. This paper incorporates petrology, LA-ICP-MS zircon U-Pb geochronology, and whole-rock major and trace element data obtained from the Kekesha intrusion in the eastern section of the East Kunlun Orogen. The formation age, petrogenesis, and magmatic source region of the intrusion are revealed, and the early tectonic evolution process of the subduction of the Proto-Tethys Ocean is discussed. The Kekesha intrusion includes four main rock types: gabbro, gabbro diorite, quartz diorite, and granodiorite. The zircon U-Pb ages are 515.7 ± 7.4 Ma for gabbro, 508.9 ± 9.8 Ma for gabbro diorite, 499.6 ± 4.0 Ma for quartz diorite, and 502.3 ± 9.3 Ma and 501.6 ± 6.2 Ma for granodiorite, respectively, indicating that they were formed in the Middle Cambrian. The geochemical results indicate that the gabbro belongs to the high-Al calc-alkaline basalt series, the gabbro diorite belongs to the medium-high-K calc-alkaline basalt series, the quartz diorite belongs to the quasi-aluminous medium-high-K calc-alkaline I-type granite series, and the granodiorite belongs to the weakly peraluminous calc-alkaline I-type granite series, all of which belong to the medium-high-K calc-alkaline series that have undergone varying degrees of differentiation and contamination. Gabbro and gabbro diorite exhibit significant enrichment in light rare earth elements (LREEs), depletion in heavy rare earth elements (HREEs), and an enhanced negative anomaly in Eu (Europium). Compared to gabbro and gabbro diorite, quartz diorite and granodiorite exhibit more pronounced enrichment in LREEs, more significant depletion in HREEs, and an enhanced negative anomaly in Eu. All four rock types are enriched in large-ion lithophile elements (LILEs) such as Cs, Rb, Th, Ba, and U, and are depleted in high-field-strength elements (HFSEs) such as Nb, Ta, and Ti. This indicates that these rocks originated from the same or similar mixed mantle source regions, and that they are formed in the island-arc tectonic environment. This paper suggests that the gabbro and gabbro diorite are mainly derived from the basic magma formed by partial melting of the lithospheric mantle metasomatized by subducted slab melt in the oceanic crust subduction zone and mixed with a small amount of asthenosphere mantle material. Quartz diorite results from the crystal fractionation of basic magma and experiences crustal contamination during magmatic evolution. Granodiorite forms through the crystal fractionation of basic magma, mixed with partial melting products from quartz diorite. While the lithology of the intrusions differs, their geochemical characteristics suggest they share the same tectonic environment. Together, they record the geological processes associated with island-arc formation in the East Kunlun region, driven by the northward subduction of the Proto-Tethys Ocean during the Early Paleozoic. Based on regional tectonic evolution, it is proposed that the Proto-Tethys Ocean began subducting northward beneath the East Kunlun block from the Middle Cambrian. The Kekesha intrusion formed between 516 and 500 Ma, marking the early stages of Proto-Tethys Ocean crust subduction. Full article

The petrology, geochemistry, and zircon U-Pb chronology of the Huoshaodian pluton in the Liuba area of the western part of the South Qinling tectonic belt are investigated in this study. The Huoshaodian pluton consists of gabbro, quartz diorite, and granodiorite, and the dominated rock type is quartz diorite. The results indicate that the Huoshaodian pluton belongs to the calc-alkaline series. In the chondrite-normalized REE, all of the samples showed similar patterns, with an enrichment of light REEs and depletion of heavy REEs, but they showed slight differences in the degrees of Eu anomalies. The primitive mantle-normalized trace element diagram reveals an enrichment of large-ion lithophile elements (LILEs) and light rare earth elements (LREEs), as well as depleted high field strength elements (HFSEs). The zircon U-Pb dating results reveal that the gabbro, quartz diorite, and granodiorite have crystallization ages of 214.9 ± 0.58 Ma, 215.0 ± 1.2 Ma, and 215.4 ± 1.9 Ma, respectively, indicating that the Huoshaodian pluton was emplaced during the late Triassic period (214.9–215.4 Ma). In terms of petrogenesis, the gabbro of the Huoshaodian pluton originates from a transitional lithospheric mantle that has undergone fluid metasomatism and partial melting. Specifically, it originated through 1%–2% garnet spinel peridotite undergoing partial melting. In addition, the gabbro underwent a slight degree of contamination by crustal materials during its ascent and intrusion, with some continental crust material being incorporated. The quartz diorite and granodiorite of the Huoshaodian pluton are formed through partial melting processes occurring within the normal lower crust. Combined with the previous studies on the early Mesozoic tectonic evolution of the South Qinling, this study proposes that the formation mechanism of the Huoshaodian pluton may be as follows: in the early Triassic, the Mianlue Ocean subducted northward beneath the Qinling microblock, resulting in a large-scale continental-continental collision between the North China Block and the Yangtze Block; when the oceanic crust subducted to a certain depth, the detachment of the subducting slab triggered the upwelling of mantle material. The heat from mantle-derived magma caused the partial melting of the mafic lower crust, while the mafic magma entered into the upper granitic magma chamber and began to mix. Due to the high viscosity contrast and temperature difference between the two end-member magmas, incomplete mixing led to the formation of a melt with distinct adakitic characteristics and a mafic melt representing mantle-derived material. Full article

The early Permian mafic–ultramafic intrusion-related Cu-Ni mineralization in Northern Tianshan offers valuable insights into the nature of the mantle beneath the Central Asian Orogenic Belt (CAOB) and enhances the understanding of magmatic sulfide mineralization processes in orogenic environments. The Yunhai intrusion, rich in Cu-Ni sulfides, marks a significant advancement for Cu-Ni exploration in the covered regions of the western Jueluotag orogenic belt in Northern Tianshan. This intrusion is well-differentiated, featuring a lithological assemblage of olivine pyroxenite, hornblende pyroxenite, gabbro, and diorite, and contains about 50 kilotons of sulfides with average grades of 0.44 wt% Ni and 0.62 wt% Cu. Sulfide mineralization occurs predominantly as concordant layers or lenses of sparsely and densely disseminated sulfides within the olivine pyroxenite and hornblende pyroxenite. In situ zircon U-Pb dating for the Yunhai intrusion indicates crystallization ages between 288 ± 1 and 284 ± 1 Ma, aligning with several Cu-Ni mineralization-associated mafic–ultramafic intrusions in Northern Tianshan. Samples from the Yunhai intrusion exhibit enrichment in light rare earth elements (LREE), distinct negative Nb and Ta anomalies, positive ε_Nd(t) values ranging from 2.75 to 6.56, low initial (⁸⁷Sr/⁸⁶Sr)_i ratios between 0.7034 and 0.7053, and positive ε_Hf(t) values from 9.27 to 15.9. These characteristics, coupled with low Ce/Pb (0.77–6.55) and Nb/U (5.47–12.0) ratios and high Ti/Zr values (38.7–102), suggest very restricted amounts (ca. 5%) of crustal assimilation. The high Rb/Y (0.35–4.27) and Th/Zr (0.01–0.03) ratios and low Sm/Yb (1.47–2.32) and La/Yb (3.10–7.52) ratios imply that the primary magma of the Yunhai intrusion likely originated from 2%–10% partial melting of weak slab fluids–metasomatized subcontinental lithospheric mantle (peridotite with 2% spinel and/or 1% garnet) in a post-collisional environment. The ΣPGE levels in the Yunhai rocks and sulfide-bearing ores range from 0.50 to 54.4 ppb, which are lower compared to PGE-undepleted Ni-Cu sulfide deposits. This PGE depletion in the Yunhai intrusion’s parental magma may have been caused by early sulfide segregation from the primary magma at depth due to the high Cu/Pd ratios (43.5 × 10³ to 2353 × 10³) of all samples. The fractional crystallization of minerals such as olivine and pyroxene might be a critical factor in provoking significant sulfide segregation at shallower levels, leading to the extensive disseminated Cu-Ni mineralization at Yunhai. These characteristics are similar to those of typical deposits in the eastern section of the Jueluotage orogenic belt (JLOB), which may indicate that the western and eastern sections of the belt have the same ore-forming potential. Full article

Intermediate-acidic granites occur extensively in the Chazangcuo copper-lead-zinc mining area (hereinafter referred to as the Chazangcuo mining area) in Tibet, China. Exploring their rock types, sources, and tectonic settings is essential for understanding the genesis of granites in the region. This study investigated the petrology of the Chazangcuo granites, as well as the geochemical characteristics of their major elements, trace elements, and rare earth elements (REEs). Results indicate that the Chazangcuo granites are high-K calc-alkaline metaluminous rocks. These granites are enriched in large-ion lithophile elements (LILEs; e.g., Rb and Ba), depleted in high-field-strength elements (HFSEs; e.g., Nb, Ta, Zr, and Hf), with a relative enrichment in light rare earth elements (LREEs), and relatively depleted in heavy rare earth elements (HREEs), exhibiting a V-shaped distribution pattern and weak negative Eu anomalies. The granites are classified as typical I-type granites, displaying characteristics of crust-derived magmas with contributions from mantle sources and exhibiting significant fractional crystallization. The Chazangcuo granites were derived from the partial melting of mafic rocks, with protoliths formed in a moderate temperature environment. Influenced by the subduction of the Neotethys Ocean, the Chazangcuo granites were formed in an arc caused by the collision between the Indian and Eurasian plates (also referred to as the Indo–Eurasian collision) during the Late Triassic. Under the effect of geological activities such as upwelling of the asthenosphere and fluid intrusion and differentiation, metal mineralization was prompted to be distributed in the granite fissures, forming the Cu-Pb-Zn polymetallic deposits of Chazangcou in Tibet, suggesting that the granites are closely associated with mineralization. Full article

The Mingshan reservoir of the Dabie Orogen has a number of Neoproterozoic bimodal intrusive rocks. We focused on the zircon U-Pb chronology, Hf isotopes, and bulk-rock geochemistry of these rocks. The results showed the following: (1) The bimodal intrusive rocks mainly consist of monzogranitic gneiss and plagioamphibolite, with zircon U-Pb ages of 785.0 ± 7.1 Ma and 787.3 ± 6.1 Ma, respectively. These ages indicate that they were formed in the late Qingbaikou epoch of the Neoproterozoic era. (2) The monzogranitic gneiss was dominated by peraluminous features and displayed a strong right deviation of REE (rare-earth element) patterns and a negative δEu anomaly. It is enriched in the LILEs (large-ion lithophile elements) Rb, Ba, and K, but slightly depleted in Nb, Sr, P, and Ti, with low 10,000* Ga/Al values, indicating that it is similar to Al-type granite. The plagioamphibolite belongs to the metaluminous, peraluminous series. It has a Mg^# (molar ratio of Mg to Mg + Fe) of 36.1~55.9 and is enriched in the LILEs Rb, Ba, and K, with a slight positive anomaly of Ba, and is depleted in Nb and Sr. (3) The monzogranite shows negative zircon εHf(t) values ranging from −13.4 to −7.2 and a Paleoproterozoic T_DM2(Hf) (two-stage depleted mantle model age) of 1969–2298 Ma. The zircon εHf(t) values and T_DM2(Hf) of the plagioamphibolite were concentrated around 2.9–5.7 and 1257–1410 Ma, respectively. The geochemistry and Hf isotopes show that the monzogranitic gneiss and plagioamphibolite have distinct magmatic sources. The plagioamphibolite formed from mantle and partial continental crustal materials. The monzogranitic gneiss, on the other hand, was formed as a result of the partial melting of the shallow ancient felsic crust caused by mafic rock heating or upwelling. Taking into account regional correlation, the middle Neoproterozoic bimodal intrusive rocks originated in the structural framework of an extensional setting. Full article