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Hydrothermal rutile (TiO2) is a widely distributed accessory mineral in hydrothermal veins or alteration assemblages of porphyry deposits and provides important information for further understanding hydrothermal fluid signatures. This study determines the geochemical composition and U-Pb dates of hydrothermal rutile from the Yulong porphyry Cu-Mo deposit in east Tibet, China. Three types of TiO2 polymorphs have been identified based on their Raman spectroscopic, textural, and chemical characteristics. (1) Brookite and anatase pseudomorphs after titanite in a fine-grained matrix, indicating low-temperature hydrothermal fluids destabilizing primary Ti-bearing minerals during argillic alteration (type-I). (2) Elongated and prismatic rutile present in hydrothermal veins or in clusters in accompanying alteration envelope characterized by weak zoning (type-II). And (3) rutile intergrown with sulfides in hydrothermal veins, characterized by well-developed patchy and sector zoning (type-III). In contrast to the type-I and type-II TiO2 polymorphs, tungsten is enriched in backscattered bright patches and sector zones in type-III rutile, which is due to the substitution of W6+ in the Ti4+ octahedral site. The mechanism of the enrichment of tungsten is effectively driven by the halogen-rich (F, Cl) aqueous fluids during hydrothermal mineralization. In situ U-Pb dating of the type-III rutile yields a lower intercept age of 41.8 ± 1.2 Ma, which brackets the timing of the Cu-Mo mineralization. The relationship between rutile textures and composition indicates that W-bearing rutile can serve as a recorder of hydrothermal processes in porphyry Cu deposits.

Granite–greenstone successions and associated tonalite–trondhjemite–granodiorite (TTG) suites constitute dominant components of Precambrian cratons. Here, we present petrology, geochemistry, zircon U–Pb geochronology, and Lu–Hf isotopes on monzonite, granodiorite, granite, and amphibolite from the Dengfeng Complex in the southern part of the North China Craton (NCC). Zircon U–Pb data yield weighted mean 207Pb/206Pb ages of 2498 ± 6 Ma for monzonite, 2481 ± 16 Ma for granodiorite, and 2475 ± 21 Ma for granite. Lu–Hf isotope systematics show eHf(t) values ranging from 1.3 to 6.7 and crustal model ages ( $$T_{{{\text{DM}}}}^{{\text{C}}}$$ ) in the range of 2584–2934 Ma for the rocks. The monzonite, granodiorite, and granite show moderate total rare-earth element (REE) contents, enrichment in light REEs (LREE) and depletion in heavy REEs (HREE), negative Nb, Ta, and Ti anomalies, high Al2O3, Sr/Y, and (La/Yb)N ratios, with low Cr and Ni, indicating that the magma was possibly sourced from partial melting of the lower crust. The geochemical features of amphibolites are characterized by low SiO2, Na2O, K2O, Sr/Y, (La/Yb)N and high FeO, low total REEs values, limited LREE/HREE fractionation, and absence of obvious Ce anomaly, showing similarity to island arc magmatic rocks. Our results are consistent with the model of subduction and arc–continent collision in the Trans-North China Orogen during the Neoarchean to Paleoproterozoic.

Rutile is an important ore mineral to meet the increasing demand of critical metal Ti in various sectors. Here we report a rare example of rutile deposits hosted within the Baishugang–Wujianfang amphibolite-facies metamorphic rocks in the East Qinling Orogen, central China. The rutiles are mostly located within or along the margins of biotite and show 94.6 to 99 wt% TiO2. Rutiles occur as chains, thin layers along the foliation, and dense clusters. The grains are coexisted with magnetite. Based on Zr-in-rutile thermometer the estimated crystallisation temperature is at 630 °C at 7.0 kba. Based on Cr/Nb ratio, the source of the rutile is correlated with Ti-bearing silicate minerals such as biotite from aluminous sedimentary protoliths. The rutile deposit formed during lower amphibolite-facies metamorphism, and is distinct from the eclogite- and granulite-related types elsewhere in the orogen. The LA-ICP-MS U–Pb analyses of rutiles from the deposit yield lower intercept 238U/206Pb ages of 386 ± 16 Ma at the Baishugang–Wujianfang district. These ages correspond to a Devonian arc–continent collisional event between the South and North Qinling domains in the East Qinling Orogen.

Tonalite–trondhjemite–granodiorite (TTG) suites constitute dominant components of Precambrian continental crust and provide important insights into the crustal evolution history of the early Earth. Here we investigate a suite of TTGs and associated greenstones from the Luxi Terrane in the south–eastern part of the North China Craton (NCC). We present data from petrology, geochemistry, zircon U–Pb geochronology and Lu–Hf isotopes to characterize these rocks and understand their genesis. Mineral assemblage in the greenstones and TTGs suggests that the rocks have undergone amphibolite–facies metamorphism with regression under greenschist–facies. Zircon U–Pb data from the magmatic grains yield upper intercept ages of 2753 ± 37 and 2582 ± 40 Ma for greenstone, 2552 ± 13 Ma for TTG gneiss and 2476 ± 18 Ma for tonalite, and weighted mean 207Pb/206Pb age of 2507 ± 22 Ma for granodiorite. Lu–Hf isotope systematics show eHf(t) values ranging from −2.13 to 7.29 and crustal model ages (TCDM) in the range of 2603–3125 Ma for the TTGs, whereas the eHf(t) values are up to 8.53 with TCDM ages of 2644–3006 Ma for the greenstone. The results suggest that the protolith for the greenstone was derived from a Meso- to Neoarchean mantle contaminated by the crust source, whereas the TTGs were mostly sourced from juvenile crustal sources with reworking of older basement. The geochemical features of greenstone are similar to island arc basalt, with low Na2O, K2O and TiO2, low total rare earth elements (REEs) values, relative enrichment in light REEs and depletion in heavy REEs absence of obvious Ce anomaly, and negative Nb, Ta and Ti anomalies. The TTGs show similar features, except for the high K2O content and moderate total REEs values. We propose that the greenstone likely represent a part of the early and initial crustal growth at ca. 2750–2600 Ma, and the TTGs were generated subsequently at ca. 2550–2450 Ma. Our results are consistent with the previous models on the crustal growth models in the NCC and provide further insights into the Neoarchean to Paleoproterozoic tectonic history of the craton.

Research on history of the Earth’s continents and the genesis of mineral deposits has been one of the hotspots in geology. But only limited studies have been completed on iron deposits hosted by banded iron-formations (BIFs), such as the large Hanwang iron deposit located in the eastern North China Craton (NCC). In this contribution, we present the petrology, zircon U–Pb geochronology, Lu–Hf isotopes and whole-rock geochemistry on Hanwang iron deposit hosted by the metamorphosed Neoarchean to early Paleoproterozoic Taishan Group and orthogneiss derived from tonalite–trondhjemite–granodiorite (TTGs). Magnetite-bearing amphibolite, magnetite-bearing quartz amphibolite, and gneiss host the Hanwang iron deposit, which is characterised by subhedral to euhedral magnetite, pyrite with minor galena and BIF laminations. Gangue minerals include hornblende, plagioclase and quartz with minor amounts of biotite, chlorite, epidote and microcline. This mineral assemblage is indicative of amphibolite-facies metamorphism with regression to greenschist-facies. The deposit is located in a transition zone between metamorphosed mafic to felsic volcanic rocks. The age of the Hanwang BIF-hosted iron deposit is late Neoarchean. Lu–Hf isotope systematics indicate that the protolith for the biotite amphibolite is derived from a Neoarchean mantle contaminated by the crust, and orthogneiss is derived from the Neoarchean crust. The biotite amphibolite is characterised by high Na, Fe and low K assays, enrichment in light rare earth elements (LREE), and relatively depletion in heavy REEs (HREE) without an obvious Ce anomaly. The geochemistry of the orthogneiss is characteristic of a volcanic–arc granite, although this must be accepted with caution given that the orthogneiss is metamorphosed and deformed at amphibolite-facies. It is proposed that Hanwang iron deposit was deposited in a marine volcanic–arc environment and derived from hydrothermally leached volcanic units, and similar to the Algoma-type iron deposit. Most BIFs occurring in Neoarchean granite-greenstone succession of the eastern NCC belong to the Algoma-type iron deposits. Globally, this sequence appears to be coeval with the Yilgarn Craton in Western Australia.

The Tieshanmiao hosted by the metamorphosed Paleoproterozoic Upper Taihua Group, is a large-scale BIF–hosted Fe deposit in the southern margin of the North China Craton. The formation age, BIF type, depositional condition as well as the genesis of pyroxene–rich BIF is under heated debate. In this study, we present petrology, whole–rock geochemistry, zircon U–Pb geochronology and Lu–Hf isotope analyses on the Tieshanmiao Fe deposit. The Fe ore of the deposit can be divided into two sub-types, including banded pyroxene–magnetite quartzite (BMQ) and disseminated magnetite pyroxenite (DMP). The hanging wall rock pyroxene biotite gneiss yields an upper intercept age of 2406 ± 24 Ma, interpreted as the lower limited age for BIF deposition. The foot wall rock garnet–bearing biotite plagioclase gneiss yields a weighted mean 207Pb/206Pb age of 2739 ± 12 Ma, interpreted as its maximal depositional age. Lu-Hf isotope systematics indicates that pyroxene biotite gneiss is derived from the Paleoproterozoic mantle contaminated by the crust, and the provenance of garnet–bearing biotite plagioclase gneiss is derived from a Mesoarchean crust. The primary mineral assemblages of the pyroxene–rich Tieshanmiao Fe deposit are Fe–silicate, Ca/Mg–carbonate, ferrihydrite, and minor quartz. The BMQs have high and variable Y/Ho ratios (40–80), recording periodic alkaline hydrothermal injection that is progressively diluted by seawater, while the DMPs have low and constrained Y/Ho ratios, archiving well–supplied alkaline hydrothermal injection. We propose a REY (lanthanide elements and Y) modelling of multi–Fe sources for the Tieshanmiao BIF deposit. The BMQs are sourced from seawater and high–T hydrothermal fluid, while the DMPs are sourced from seawater, high–T hydrothermal fluids and one or several additional Fe fluxes (e.g. high-Fe dissolved riverine fluxes, low–T hydrothermal fluids or benthic Fe shuttles driven by dissimilatory iron reduction). The basic gneisses as metabasalts associated with the Tieshanmiao Fe deposit are characterized by high–Fe assay, variable LREE enrichment, relatively depletion in Nb, Ta, Zr, Ti, Y, and Th. The geochemistry of the basic gneisses shows affinities to both MORBs and volcanic–arc basalts, indicating a back–arc basin setting of the BIF deposition. It is most likely a Superior–type BIF–hosted Fe deposit, which is formed in a back–arc basin along the craton–side continental shelf.

Liancheng is an important Cu–Mo deposit hosted by red-beds in the Mesozoic to Cenozoic Lanping Basin located in the Sanjiang Tethyan Orogen of SW China. The deposit is fault controlled where it has been affected and enriched by four hydrothermal events indicated by four distinct sets of veins and their cross-cutting relationships. A detailed Cu–S–H–O isotopic study is reported here on the mineralization focusing on the source of the metals and fluid, and on the mineralizing processes. The first two hydrothermal events are characterised by CO2 and fluid-rich inclusions with homogenisation temperatures of 124–446 °C and salinities ranging from 0.4 to 24.6 wt% NaCl equiv. The next two hydrothermal events are characterised by liquid–rich fluid inclusions that homogenise at 145–256 °C, with salinities ranging from 1.4 to 22.9 wt% NaCl equiv. The H–O isotope values obtain from the fluid inclusions indicate that the first three hydrothermal events relate to mineralizing fluids derived from a metamorphic source, but the last event includes a mixed metamorphic and meteoric source. Chalcopyrite, tennantite, and bornite from the deposit have δ34S values between −11.5 and 3‰. The δ65Cu values for quartz-Cu sulfide mineralization associated with the second hydrothermal event range from −0.31 to 0.2‰, but carbonate-Cu sulfide mineralization associated with the third hydrothermal event ranges from −1.01 to −1.08‰. The combination of the Cu and S isotopic values and field observations indicate that the controlling factors include structures, the temperature of regional metamorphism, and the pH of the mineralizing fluid. The zation is, therefore, characteristic of an orogenic-type deposit.

The Sanjiang Orogen is important for us to better understand the tectonic evolution of the Paleo-Tethys Ocean. However, the petrogenesis and tectonic setting of the Late Triassic igneous rocks in the central part of the orogen are poorly understood. In this study, we present new whole-rock elemental and isotopic compositions for the Biluoxueshan Pluton, which consists of quartz diorite, granodiorite, and alkali-feldspar granite. Zircon U-Pb dating yields crystallisation ages of 231 ± 1 Ma for the quartz diorite, 227 ± 1 Ma for the granodiorite, and 227 ± 2, 224 ± 2, 222 ± 1, and 217 ± 3 Ma for alkali-feldspar granites, indicating a prolonged emplacement of the pluton. Quartz diorites are metaluminous, high-potassium calc-alkaline, and magnesian in composition. Granodiorites are characterized by peraluminous composition and the existence of normative-corundum, resembling S-type granite. They have negative zircon eHf(t) values (−13 to −10.8) and old Hf crustal model ages (2060–1920 Ma), indicating a Paleoproterozoic crustal source. Alkali-feldspar granites are metaluminous to weakly peraluminous, have higher SiO2 content, FeOT/MgO ratio and differentiation index (DI) than other samples, and pronouncedly negative Eu anomalies, which are characteristics of highly fractionated granites. They have narrow eHf(t) values of −2.7 to +2.6 with corresponding Hf crustal model ages of 1410–1060 Ma, indicating a Mesoproterozoic juvenile crustal source modified by mantle-derived magma. By combining previous and the new data, we proposed a new tectonic evolution model of a Late Triassic northward scissor-like post-collisional extension during ca. 235–223 Ma in the Changning-Menglian Suture Zone.

The North China Craton (NCC) preserves important records of Archean-Paleoproterozoic crustal evolution. Here we present results from petrology, geochemistry, zircon U-Pb dating and Lu-Hf isotopes of the Taihua Complex (THC) from the southern part of the NCC. Zircon U-Pb dating of the amphibolite yields the ages of 2776–2771 Ma representing the formation age, marking a major phase of late Archean crustal growth in the NCC. The 1922–1915 Ma ages represent the Paleoproterozoic metamorphism associated with the collisional assembly between the Eastern and Western Blocks. The amphibolites are characterized by low SiO2, Na2O + K2O, and Nb/Y, indicating a sub-alkaline basaltic protolith. These rocks show relatively high LILE/HFSE and LREE/HREE ratios, similar to E-MORB, low [Nb/La]PM, negative Nb-Ta anomalies and positive eHf(t) values indicating partial melting of a metasomatic mantle source. The TTG gneisses are characterized by high SiO2, Sr/Y, (La/Yb)N, Nb/Ta, Zr/Sm and Zr/Hf ratios, and low MgO, Cr, Ni, Y, Gd/Yb and Dy/Yb ratios, with positive Eu anomalies, indicating partial melting of juvenile lower crust with garnet-amphibolite residue. Our data are consistent with a tectonic setting within a volcanic arc in a convergent margin. Our study on the THC contributes to the Archean-Paleoproterozoic crustal accretion and reworking history along the southern margin of the NCC.