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The Laird Lake property, southwest Red Lake greenstone belt, straddles the contact between the Balmer (2.99–2.96 Ga) and the Confederation (2.74–2.73 Ga) assemblages. The property is 10 km along strike from the Madsen and Starrat–Olsen Au mines that are hosted near the contact. The Balmer assemblage consists of fine-grained, aphyric, locally pillowed mafic volcanic rocks, ultramafic intrusive and volcanic rocks with flow breccia textures hosting local spinifex-bearing clasts, and banded-iron formations. In contrast, the Confederation assemblage comprises porphyritic mafic volcanic rocks intercalated with intermediate to felsic volcanic rocks that include crystal lapilli tuffs, crystal tuffs, and tuffs. The Balmer assemblage is composed of tholeiitic mafic volcanic rocks with minor Al-undepleted komatiites, whereas the Confederation assemblage is calc–alkalic. Neodymium isotopes, in conjunction with trace element geochemistry, suggests that parts of the Balmer assemblage were weakly contaminated by an older intermediate basement. Both arc and back-arc volcanism occurs in the Confederation assemblage, with the arc rocks showing a stronger crustal component than the back-arc rocks. A maximum U–Pb age of 2741 ± 19 Ma for a crystal tuff and an age of 2737.68 ± 0.79 Ma for a diorite are consistent with a Confederation assemblage affinity for the intermediate calc–alkaline rocks south of the Au-bearing horizon. The Balmer assemblage represents an oceanic plateau formed by plume magmatism on the margins of the North Caribou Terrane, whereas the Confederation assemblage at Laird Lake formed in an oceanic arc setting where both arc and back-arc volcanism occurred simultaneously. [ABSTRACT FROM AUTHOR]

The Dayinsu area is located in the northern part of the West Junggar district near the border between China and Kazakhstan and is an important component of the Central Asian Orogenic Belt (CAOB). The Dayinsu area hosts numerous granitoid plutons in Devonian–Carboniferous volcano–sedimentary strata. The older Laodayinsu and Kubei (345–330 Ma) plutons are located in the west with the younger Bayimuzha and Qianfeng (330–325 Ma) plutons in the east. The whole-rock SiO2contents of the four granitoid plutons range from 52.22 to 68.42 wt.% and total alkaline contents (K2O + Na2O) range from 4.94 to 9.16 wt.%. The granites are enriched in large ion lithophile elements and light rare earth elements with depletions in Nb, Ta, Ce, Pr, P, and Ti. The plutons are metaluminous with I-type signatures. The geochemistry of the intrusions suggests that they formed in a subduction zone setting, and subsequently underwent fractional crystallization during emplacement, with higher degrees of fractionation in the eastern sector than in the west. Similarities in the geochronology and geochemical characteristics of the granitoid plutons in Dayinsu to those in the Tabei district (west to Dayinsu area) suggest that both districts are part of the Carboniferous Tarbagatay Mountain intrusive event. The early Carboniferous (345–324 Ma) granitoid intrusions in the Tarbagatay Mountain likely formed in an island arc subduction setting during the evolution of the CAOB. [ABSTRACT FROM PUBLISHER]

The newly discovered Caixiashan Irish-type Zn-Pb deposit (∼131 Mt at 3.95 % Zn + Pb), located in the Eastern Tianshan of Xinjiang, is one of the largest Zn-Pb deposits in NW China. Massive colloform/framboidal textured syn-sedimentary pyrite yielded a Re-Os isochron age of 1019 ± 70 Ma (MSWD = 3.5), which is interpreted to be the depositional age of the Kawabulake group that hosts the ore. The age of the main mineralization stage is constrained by two types of pyrite: the layered pyrite coexists with recrystallized calcite and dolomite and is locally replaced by sphalerite, whereas the euhedral pyrite occurs with galena that crosscuts the massive sphalerite. The layered pyrite yielded a Re-Os age of 859 ± 79 Ma (MSWD = 6.7; initial Os/Os ratio [I] = 0.19 ± 0.25) and the euhedral pyrite 837 ± 39 Ma (MSWD = 6.5; [I] = 0.16 ± 0.09), which are interpreted to be the Zn and Pb mineralization ages, respectively. The low radiogenic initial Os values of the Zn-Pb mineralization suggest interaction between a hydrothermal fluid and a mafic or ultramafic source rock with a mantle Os signature with some contamination with Mesoproterozoic Kawabulake group. Based on our new Re-Os ages, we conclude that the giant Caixiashan Zn-Pb deposit formed in the early Neoproterozoic and it represents a newly identified mineralization epoch in the Eastern Tianshan of the Central Asia Orogenic Belt. [ABSTRACT FROM AUTHOR]

Abstract: The ∼3Ga North Caribou greenstone belt comprises a package of volcanic and sedimentary rocks metamorphosed from greenschist to upper amphibolite grade, surrounded by ∼2.7–3.0Ga granitoids and gneisses and is host to the Musselwhite gold mine, a large orogenic gold deposit. New U–Pb (zircon, monazite), Ar–Ar (biotite) and Sm–Nd (garnet) ages for volcanic, sedimentary and intrusive rocks from the Musselwhite mine and surrounding plutons have been obtained. Felsic volcanic rocks yielded ages of 2972.4±1.6 and 2982.4±0.8Ma, broadly consistent with existing ages for volcanic rocks and plutonism. An age of 2857.3±1.4Ma for the Schade Lake gneiss is consistent with published plutonic and volcanic ages. A younger, and previously unrecognized, plutonic event is represented by three granites dated at 2723.1±0.8, 2727.7±1.0 and 2729.4±7.1Ma. An Sm–Nd age of 2690±9Ma for garnets associated with gold mineralization is bracketed by peraluminous granites with ages of 2668.8±1.1 and 2715.8±1.6Ma. Ar–Ar ages range from 2420±11.97 to 2658±13.46Ma, broadly synchronous with the youngest intrusive age, and are consistent with progressive resetting due to metamorphism. The new geochronological data for the NCGB show that volcanism in the Opapimiskan Lake area spanned 10 million years from 2982.4 to 2972.4Ma, allow for new stratigraphic interpretations of the belt and are broadly correlative with other greenstone belts in the North Caribou terrane. The new data for the NCGB and associated plutons are consistent with ∼3Ga plume-related activity forming a proto-craton that was the site of successive sedimentary basins over the next ∼150 million years. Subsequent plutonism is consistent with supra-subduction zone processes at the margins of this proto-continent by ∼2.87Ga and is best interpreted as the result of horizontal tectonic processes consistent with those operating in the Phanerozoic, with the plutons emplaced behind continental margin arcs on the edges of the craton. Sm–Nd ages of garnets that are coeval with mineralization suggest that the orogenic gold mineralization at the Musselwhite mine was broadly synchronous with the ∼2700Ma orogeny caused by the collision of the Oxford-Stull domain with the North Caribou terrane ∼75km northeast of the Musselwhite mine and furthermore argues that S-type granites may play a greater role in the formation of some orogenic gold deposits than has been previously recognized. [Copyright &y& Elsevier]

Abstract: The Midcontinent Rift (MCR) of North America comprises a series of basaltic sheets, flows and intrusive rocks emplaced in the Lake Superior region during the Mesoproterozoic. The mafic rocks preserved on the northern flank of Lake Superior represent the older portions of the rift sequence and offer insights into the early development of the rift. New geochronological, geochemical and paleomagnetic data are presented for the dikes and sills located in and south of Thunder Bay, Ontario. Three sill suites are recognized within the study area; an earlier, spatially restricted ultramafic unit termed the Riverdale sill, the predominant Logan sills and Nipigon sills in the north of the study area. In addition three dike sets are recognized, the north-east trending Pigeon River swarm, the north-west trending Cloud River dikes and the Mt. Mollie dike. The geochemical data demonstrate that the majority of sills south of Thunder Bay are of Logan affinity and distinct from those of broadly similar age in the Nipigon Embayment to the north. The Pigeon River dikes that intrude the sills are geochemically coherent but distinct from the Logan sills and could not be feeders to the sills. The new age of 1109.2±4.2Ma for the Cloud River dike and its R polarity are consistent with published magnetostratigraphy. The Mt. Mollie dike age (1109.3±6.3Ma) indicates that it is not coeval with the spatially associated Crystal Lake gabbro as previously thought. The complexity of the dike and sill suites on the northern flank of suggests that the early phases of rifting occurred in distinct and changing stress fields prior to the main extensional rifting preserved in younger rocks to the south. The geochemistry and geochronology of the intrusions suggest a long-lived and complex magmatic history for the Midcontinent Rift. [ABSTRACT FROM AUTHOR]

[Display omitted] • Yuleken porphyry Cu-Mo deposit is a superimposed porphyry deposit. • Rb-Sr isotopes of chalcopyrite show that it formed during deformation. • The trace element and in situ -S isotope of chalcopyrite can distinguish distinct episodes of mienralization. The Yulekenhalasu porphyry Cu–Mo deposit is located ca. 40 km southwest of Qinghe, in the Chinese Altay-East Junggar section of the Central Asian Orogenic Belt, NW China. The belt preserves multistage tectonic-hydrothermal and porphyry Cu-Mo mineralization events associated with arc to syn- and post-collision environments over 87 m.y. The 359 Ma deformed granitic porphyries are characterized by positive ε Nd(t) (+0.62 to + 3.77) and (87Sr/86Sr) initial values (0.704304–0.705960), and old crustal model ages of 747 to 1216 Ma, whereas a 272 Ma sample from late chalcopyrite–molybdenite–pyrite–magnetite–feldspar–calcite–gypsum veins yielded (87Sr/86Sr) initial values of 0.704415 to 0.705764, high ε Nd(t) values (+5.81 to + 5.88) and young crustal model ages (715 to 614 Ma) suggesting an increasingly juvenile mantle source over time. Seven fragments of a single deformed chalcopyrite grain yielded an Rb-Sr isochron age of 358.6 ± 4.8 Ma (2σ, MSWD = 1.8), which is consistent with the 360 Ma recrystallized zircon grains in the deformed host granitic porphyries. Eight fragments of chalcopyrite from the chalcopyrite–molybdenite–pyrite–magnetite–feldspar–calcite–gypsum veins formed along cleavage planes yielded a younger Rb-Sr isochron age of 272.2 ± 2.6 Ma (2σ, MSWD = 1.8). The younger age is interpreted as the lower age limit for the Mo and Cu mineralization in the post-collisional stage. The heterogeneous initial Sr isotopic compositions of chalcopyrite in the Yulekenhalasu deposit are likely the result of phyllosilicate inclusions. Disseminated chalcopyrite crystals in the granitic porphyry have different trace elemental contents than chalcopyrite in the deformed granitic porphyry and late chalcopyrite veins. Our Rb-Sr and trace element data for chalcopyrite grains constrain the age and geochemistry of multistage mineralization in porphyry Cu-Mo deposits. In-situ S isotope data of chalcopyrite from the deformed granite porphyries and chalcopyrite-feldspar-quartz-muscovite veins display a similar mantle origin. The 272 Ma mineralization event at Yulekenhalasu is coeval with the formation age of the Cu-Ni-(PGE) sulfide deposit in the Chinese Altay, indicating that hydrothermal mineralization like that in porphyry deposits can form proximal to ultramafic–mafic rocks and potentially may have a genetic relationship with mantle-derived Cu-Ni-(PGE) sulfide deposits. [ABSTRACT FROM AUTHOR]

Deep-sea sediments rich in rare earth elements and yttrium (REY) are promising mineral resources that are believed to be associated with the burial of fish debris. However, the nature of the REY enrichment is poorly understood, in part due to a lack of robust age constraints. We report bioapatite U-Pb ages from an Ocean Drilling Program (Leg 199, Hole 1218A) core and a REY-rich sedimentary core from the Pacific Ocean, which yielded U-Pb ages rang- ing from 22.8 to 18.2 Ma and 6.5 to 2.2 Ma, respectively. The U-Pb fish teeth ages from the 1218A core are consistent with biostratigraphic constraints, shed light on the application of the U-Pb bioapatite chronometer, and yield an absolute time scale for stratigraphy, especially for sequences deposited below the calcite compensation depth (CCD), where there is an ab- sence of fossil carbonate. The successful measurement of U-Pb ages from REY-enriched fish teeth in the REY-rich sediment core suggests the mineralization occurred no later than the Miocene in the western Pacific Ocean. Uranium is positively correlated with REY, suggesting that the U and REY were incorporated into the fish teeth lattice simultaneously, making the bioapatite U-Pb chronometer suitable for constraining the timing of REY mineralization. When combined with published data, our study suggests that the Miocene REY accumula- tion event in the western Pacific Ocean was influenced by high P2O5 and MnO2 contents correlated with oxic bottom water. [ABSTRACT FROM AUTHOR]

The Zijinshan mineral field is a large porphyry-epithermal Cu Au Mo Ag ore system located in the southwestern Fujian Province, China. The Southeast (Cu Mo) Ore Segment (SOE) is a newly discovered section located in the southeastern portion of the Zijinshan mineral field. Zircon U Pb and molybdenite Re Os ages, as well as the geochemical compositions of intrusive and volcanic rocks and zircon Hf isotope data are used to constrain the timing, petrogenesis, tectonic setting and the relationship between magmatism and metallogenesis in the SOE and Zijinshan mineral field. Major and trace element geochemistry indicates that igneous rocks from SOE are mainly shoshonitic granitoids that are LILE enriched (Rb, Ba, Th, U) with HFSE depletion (Nb, Ta, Zr, Hf and Y), indicating a subduction related setting. New U Pb zircon analyses yield weighted mean ages of ca. 160 Ma for the Caixi pluton, ca. 110 Ma for the Sifang granodiorite, ca. 107–105 Ma for the Luoboling granodiorite porphyry, ca. 105 Ma for the quartz diorite porphyry, ca. 108–105 Ma for the dacite porphyry, ca. 98 Ma for the rhyodacite, and 97 Ma for the rhyolite in the SOE. These dates, integrated with previous geochronological data, indicate that there were two main magmatic events in this area: (1) a Middle to Late Jurassic event (165–150 Ma), and (2) a Cretaceous event (110–95 Ma) which can be further divided into two groups, i.e., the late Early Cretaceous event (110–105 Ma) and the early Late Cretaceous event (100–95 Ma). The late Early Cretaceous intrusions contain higher ε Hf (t) values (0.1 to − 3.6), with T DM2 varying from 1.4 to 1.0 Ga, which may come from mixing between crustal and subduction-related mantle derived melts in contrast to the Middle to late Jurassic intrusions that may come from the partial melting of the Cathaysia Block basement. The early Late Cretaceous intrusions display a broader range of ε Hf (t) values (− 0.9 to − 9.4), with T DM2 varying from 1.8 to 1.2 Ga, suggesting a similar source to the late Early Cretaceous rocks but with more crustal material. The molybdenite Re Os ages for mineralization range from 110 Ma to 105 Ma, consistent with ages of the late Early Cretaceous rocks. Zircon trace elements analyses imply that the early Late Cretaceous rocks (Ce 4 + /Ce 3 + = 113–1800) are characterized by higher oxygen fugacity with higher mineralization potential than the late Early Cretaceous (Ce 4 + /Ce 3 + = 9–545) and the Middle to Late Jurassic rocks. Variability in ages, geochemistry and oxygen fugacity indicate that the Middle to Late Jurassic magmatic event represents pre-mineralization intrusions whereas the late Early Cretaceous is syn-mineralization and the early Late Cretaceous intrusions post-mineralization. We propose that both the Middle to Late Jurassic and the Cretaceous magmatic events may relate to the subduction of the Pacific slab, and the changing direction of the subducted slab may result in the different sources for the two magmatic events. [ABSTRACT FROM AUTHOR]

The Fe-Cu mineralization of the Laoshankou district is located in the Dulate Late Paleozoic island arc at the northern margin of East Junggar terrane, Northwest China and is hosted by volcanic rocks of the Middle Devonian Beitashan Formation. LA-ICP-MS U–Pb dating of zircon constrains the timing of crystallization of biotite diorites and quartz syenites in the Laoshankou district to 379 ± 2 Ma and 376 ± 2 Ma, respectively. The volcanic rocks are calc-alkaline in composition and are characterised by LILE and LREE enrichments and HFSE depletions, consistent with a subduction-related affinity. The relatively depleted Nb, Ta, Zr, Hf and Th, enriched Sr and Ba, elevated Mg#, positive ε Nd (t) values (5.5 and 5.6), low ( 87 Sr/ 86 Sr) i ratios (0.7042 and 0.7044) and MORB-like Pb-isotope characters all suggest that they were derived from a depleted mantle wedge metasomatized by slab-derived fluids, without crustal contamination. The biotite diorite shows slightly metaluminous compositions and is geochemically similar to the volcanic rocks, suggesting that they were derived from the same depleted mantle source. The lack of correlation between SiO 2 and initial Sr, Nd ratios suggests that fractional crystallization dominated the petrogenesis of the biotite diorite with only weak crustal contamination. The geochemical characteristics of the quartz syenite are distinct from the volcanic rocks and the biotite diorite. The positive ε Hf (t), ε Nd (t), high Th/La (0.17–0.53), Th/Yb (1.62–4.39), low Ce/Th (2.87–10.13) ratios and positive trends of SiO 2 versus ( 87 Sr/ 86 Sr) i and ( 143 Nd/ 144 Nd) i indicate the quartz syenite is likely the product of a depleted mantle wedge metasomatized by slab-derived fluids and subducted sediment-derived melts that underwent crustal contamination during passage through the crust. The low abundance of Th, Yb, Ta and La, indicate that all the intrusive rocks from 379 to 376 Ma in the Laoshankou district formed in an island arc rather than a continental margin arc. The northern margin of East Junggar was related to the southward subduction of the Kuerti-Erqis Ocean (a branch of the Paleo-Asian Ocean) between the Altay and the Dulate arcs in this period, consistent with the presence of Nb-enriched basalts and boninites in the north of the Dulate arc and the island arc rather than back arc setting of the igneous rocks in the Laoshankou district. For metallogenesis in the northern margin of East Junggar, arc-related Fe-Cu-Au and porphyry Cu mineralization was dominated. There is large potential to find several Late Paleozoic arc-related Fe-Cu-Au mineralizations in North Xinjiang. [ABSTRACT FROM AUTHOR]

The East Junggar terrane (NW China) is an important constituent of the Central Asian Orogenic Belt (CAOB). From the Devonian to Permian, regional magmatism evolved from mainly calc-alkaline (I-type) to alkaline (A-type). The Qiaoxiahala Fe-Cu deposit, located in the Late Paleozoic Dulate island arc (northern margin of the East Junggar), is hosted in the volcanic rocks of the Middle Devonian Beitashan Formation. Two magmatic stages were identified in the deposit, the Qiaoxiahala diorite porphyry (380 ± 4.0 Ma) and a younger aplite (331 ± 3.1 Ma). The (high-K) calc-alkaline Beitashan Formation basaltic rocks are characterized by LILE and LREE enrichments and HFSE depletions, pointing to a subduction-related affinity. The high Mg# (42–75), elevated Ce/Th and Ba/Th, depleted Nb, positive ε Nd (t) (6.6), low ( 87 Sr/ 86 Sr) i (0.7037) and MORB-like Pb isotope characters all suggest an origin involving partial melting of a MORB-like depleted mantle wedge (metasomatized by slab-derived fluids) with little evidence of crustal contamination. The calc-alkaline (I-type) diorite porphyry, characterized by LILE and LREE enrichments and HFSE depletions, may have formed from fractional crystallization of the basaltic rocks, with its parental magma derived from the same depleted mantle wedge. The negative ε Hf (t) (−8.26), Hf model age ( T DM C ) of 1406 Ma and the presence of inherited zircons (ca. 470 and 506 Ma) indicate that the diorite has assimilated older crustal material. The alkaline, metaluminous (A-type) aplite is characterized by HFSE enrichment and depletions in Sr, P and Ti, distinct from the basaltic rocks and diorite porphyry at Qiaoxiahala. The low Mg# (35–38), positive Zr and Hf, positive ε Hf (t) (4.77–9.75) and ε Nd (t) (6.85–6.86) and low T 2DM (538–520 Ma) suggest a juvenile lower crustal source due to partial melting of basaltic lower crust as a result of underplating of mantle-derived melts and accompanied by magma mixing. The tectonic evolution of the Paleozoic East Junggar was associated with the initiation of subduction of the Paleo-Asian Ocean, with the formation of an island arc during the Early to Middle Devonian and generation of the coeval arc-related Fe-Cu (-Au) and porphyry Cu mineralization. Collision between the Chinese Altay and East Junggar happened in the Late Devonian with Early Carboniferous post-collisional tectonics likely explaining the synchronous Cu-Mo mineralization, while the late-Early to Late Carboniferous post-orogenic event ended without related mineralization in Qiaoxiahala. [ABSTRACT FROM AUTHOR]

The timing of hydrothermal activity is a key factor in any predictive genetic model of skarn mineralization, but direct dating is often hindered by the absence of suitable minerals to date. Vesuvianite, a common mineral in skarn deposits, can incorporate U and has a high Pb closure temperature (>650 °C), and consequently may be suitable for dating for skarn deposits. Vesuvianite collected from nine Chinese skarn deposits, including the Jinchuantang Sn Bi, Shizhuyuan W–Sn–Mo–Bi polymetallic, Jiepai Cu W, Dashunlong Sn, Xianghualing Sn, Furong Sn, and Huangshaping W–Sn–Mo–Cu polymetallic deposits in Nanling Range (Southern China), and the Kaerqueka and Saishitang Cu deposits in East Kunlun Orogen (Northwestern China), have high U concentrations (median 66.8 ppm for 460 LA-ICP-MS analysis spots). The flat and stable time-resolved signal spectra for U during LA-ICP-MS analysis, combined with the absence of nanoscale mineral inclusions, porosities, or lattice defects in the JCT vesuvianite, with high and consistent U concentrations, revealed by the HAADF-STEM images, and the marked positive relationships between U and REE collectively suggest that the U incorporation into vesuvianite was primarily controlled by replacement of Ca2+ in eight-fold coordination, confirming that vesuvianite may be a suitable U Pb geochronometer. The JCT vesuvianite is characterized by high and consistent U concentrations (260–526 ppm, median 307 ppm) and homogeneous internal texture and elemental distribution, and yields an ID-TIMS U Pb concordia age (2σ, 153.9 ± 0.2 Ma, MSWD = 1.6, n = 11), demonstrating that it can be taken as a potential LA-ICP-MS U Pb reference material, which can be freely distributed to other laboratories. Using the JCT vesuvianite as a U Pb reference material, the Kaerqueka, Saishitang, Jiepai, Dashunlong, Xianghualing, Furong, and Shizhuyuan vesuvianite yielded well-defined LA-ICP-MS U Pb ages (239.0–152.1 Ma, 2σ), consistent with previously published age constraints of mineralization and cogenetic igneous rocks. Vesuvianite from the Huangshaping W–Sn–Mo–Cu polymetallic deposit, yielded U Pb ages of 157.3 ± 1.4 Ma (2σ, MSWD = 1.8) and 161.0 ± 1.3 Ma (2σ, MSWD = 1.9), providing reliable constraints on the overprinting sequence of the skarn W–Sn–Mo and Cu mineralization events at Huangshaping, which was not previously detectable using other mineralization chronometers. Combined, these ages suggest that vesuvianite is a robust and reliable geochronometer, and offers a new tool for dating skarn deposits. [ABSTRACT FROM AUTHOR]

Tin deposits within the Baoshan Block in western Yunnan are posited as the northern extension of the Southeast Asian Tin Belt, yet they have been relatively underexplored in terms of geochronology. This study concentrates on the Yunling tin deposit, globally recognized for its production of gemstone-quality cassiterite crystals. We applied U–Pb geochronology on cassiterite, complemented by analyses of its trace element composition and in situ oxygen isotopes in cassiterite and quartz, aiming to delineate the deposit's age and genesis. The Yunling orebodies are hosted by deformed Triassic granite, closely adjacent to the Cenozoic Nantinghe strike-slip shear zone. Three distinct hydrothermal stages have been identified: quartz-cassiterite-muscovite-tourmaline (stage I), arsenopyrite-pyrite-cassiterite-quartz (stage II), and arsenopyrite-calcite-quartz (stage III). Cassiterite grains from a quartz-cassiterite-muscovite-tourmaline vein yield a U–Pb age of 24.4 ± 1.4 Ma (2σ, n = 41, MSWD = 1.6), notably younger than the ore-hosting Triassic granite. Paired cassiterite and quartz oxygen isotopes yield δ18OH2O values of 5.8 – 7.2 ‰, indicating a magmatic fluid source during stages I and II. The trace element compositions of the Yunling cassiterite resemble those of granite-related tin deposits, suggesting a genetic link between tin mineralization and an unexposed late Cenozoic granite intrusion. Notably, the Triassic granite of Yunling shows a lower degree of magmatic fractionation, thus presenting a limited potential for tin mineralization. The timing of mineralization is correlated with the activity of the Nantinghe fault, alongside geophysical evidence of crust-mantle decoupling and asthenosphere upwelling. Consequently, our findings imply that the Yunling tin mineralization is genetically related to hidden granites, to guide future exploration efforts in western Yunnan. [ABSTRACT FROM AUTHOR]

The Xiaoxi’nancha porphyry Au-Cu deposit is located in Yanbian, Jilin Province, NE China. Gold-Cu mineralization is mainly associated with chlorite-sericite alteration. The 40Ar/39Ar age of pre-mineralization hydrothermal biotite in potassic alteration defines a relatively well-defined cluster at ~ 111 Ma to 114 Ma with a total fusion age of 112.0 ± 0.3 Ma. In-situ secondary-ion mass spectrometry U-Pb dating of hydrothermal titanite occurring with chalcopyrite yielded an intercept age of 109.0 ± 2.4 Ma. The similarity between the biotite and titanite formation ages suggests a mineralization age of ~ 110 Ma. Chlorite, quartz and apatite coexist in equilibrium and are closely related to mineralization. The Al-in-chlorite geothermometer indicates a formation temperature of 236–351℃ (mean 309℃), and the quartz-apatite pair yielded an average formation temperature of 306℃. The in-situ δ34S compositions of sulfide have restricted and slightly positive values (pyrite 2.3 to 3.9‰, chalcopyrite 1.6 to 3.8‰ and molybdenite 2.3 to 3.7‰). The fluid δ18O values, calculated assuming quartz-fluid equilibrium, vary from 2.4 to 5.5‰ (average = 4.0‰). Therefore, the ore-forming hydrothermal fluids were of moderate-temperature with predominantly magmatic characteristics. Apatite exhibits distinct variations in structure and composition, and slight variations in oxygen isotopic composition. The areas in apatite with dark BSE textures are characterized by lower δ18O values, Cl contents and temperatures and higher F contents, consistent with the result of water–rock interaction rather than mixing with meteoric water. The water–rock interaction and its resulting cooling, can reduce the metal solubility, likely triggering mineralization at Xiaoxi’nancha. [ABSTRACT FROM AUTHOR]

• U-Pb ion microprobe measurements in zircons of 109 new samples. • Definition of two step-wise geochemical shifts in felsic to intermediate intrusions at 2.75 Ga and 2.7 Ga. • A 2.87 Ga xenocryst in the 2.72 Ga phase of the Atikwa batholith, located in the Neoarchean Western Wabigoon terrane, is the earliest isotopic evidence for a Mesoarchean heritage there. • Recognition of linked chemo-stratigraphy across isotopically distinct terranes including ∼2.8 Ga continental emergence in the Jutten and Wagita assemblages of the respective Winnipeg River and Marmion terranes. • Autochthonous development of isotopically distinct terranes of the Wabigoon superterrane. Archaean crustal growth models remain contentious. Isotopically distinct crustal domains in the Superior Craton have been interpreted as exotic terranes, which has bolstered models of Archaean subduction-accretion. However, new geochemistry and geochronology of 3.0-2.7 Ga felsic igneous rocks across the Wabigoon superterrane, Superior Craton, together with a new stratigraphic synthesis, point to a shared chemo-stratigraphy across four isotopically-defined 'terranes'. Uranium-Pb zircon emplacement ages were measured for 109 new samples by ion microprobe. Two chemical shifts were identified across 3.02–2.68 Ga magmatism. At 2.75 Ga, variability in major oxides increases and some LILE, LREE, Sr/Y and La/Lu increase. At ca. 2.69 Ga, sanukitoid-like rocks record an increase in Mg#, compatible and transition elements, P 2 O 5 , LREE and steepening of REE patterns. The 2.75 Ga shift highlights the onset of greater melting/crystallisation depths and changing magma sources, reflecting cratonic thickening. The shift follows ∼2.8 Ga continental emergence recorded in basal conglomerates at a transition from plateau-like to rift- and arc-like greenstone assemblages. The <2.7 Ga shift reflects garnet-stable melting of a metasomatised mantle and correlates with craton-wide sedimentation and orogenesis. Several age peaks in near-continuous Marmion terrane magmatism from 3.02 Ga to 2.78 Ga are contemporaneous with scattered 3.02–2.78 Ga emplacement and inherited zircon ages from the 3.4 Ga Winnipeg River and 2.9 Ga Eastern Wabigoon terranes. All terranes record major magmatic episodes at ca. 2.74-2.72 and 2.7 Ga. A 2.87 Ga zircon xenocryst in the 2.72 Ga Atikwa batholith of the Western Wabigoon terrane is the earliest isotopic evidence for Mesoarchaean basement there. Contemporaneous magmatism, evidence for Mesoarchaean zircon age inheritance in Neoarchaean terranes, and a newly hypothesized time-correlative unconformity across terranes, favours (para-) autochthonous growth of the superterrane. The granite-greenstone record is reconciled by Mesoarchaean rifting, and subsequent development of a Neoarchaean suprasubduction zone before culminating with Kenoran collision. Therefore, <2.78 Ga subduction-accretion overprinted and shortened, but did not necessarily assemble, the Wabigoon superterrane. This finding complements growing global evidence for a unique mechanism of Archaean granite-greenstone development that culminated in late, localized subduction before cratonisation, with implications for the global onset of plate tectonics in the late Archean. [ABSTRACT FROM AUTHOR]

Abstract The Jiaobei Terrane in the southeastern North China Craton (NCC) witnessed intense magmatic pulses during Mesozoic in response to lithospheric thinning. These include sporadic felsic-porphyritic dikes which preserve important information on the magmatic processes and of its implications on lithospheric thinning. Here we present a detailed investigation of representative felsic-porphyritic dikes based on whole-rock geochemical analysis, zircon LA-ICPMS U-Pb geochronology, trace elements and hafnium isotopic compositions. Our results identify stages of felsic dikes in the Jiaobei Terrane with ages in the range of 131–127 Ma and 123–116 Ma. The early stage felsic dikes (ESFDs) have negative zircon ɛ Hf (t) (−22.4 to −11.1), high zircon Eu N /Eu N * (0.41–0.92) and Ce4+/Ce3+ (62–944), low Ti-in-zircon crystallization temperatures (524–738 °C), and are geochemically comparable to the coexisting Guojialing granodiorite. Abundant inherited zircons and scattered zircon Hf, Yb/Gd, Th/U, and Ce/Sm values suggest that the magmas from which the dikes formed involved crustal contamination. They are interpreted to be the hypabyssal phase of the Guojialing suite sourced from the Paleoproterozoic lower crust of the eastern NCC with input of mantle components, associated with extensive crust-mantle interaction during the peak lithospheric thinning. The late stage felsic dikes (LSFDs) are characterized by variable zircon ɛ Hf (t), Eu N /Eu N * and Ce4+/Ce3+ values (−20.1 to −12.2, 0.38–0.88 and 64–956 for the granodiorite- and quartz-porphyritic dikes; −27.6 to −16.2, 0.17–0.75 and 22–503 for the monzogranite-porphyritic dikes), low Ti-in-zircon crystallization temperatures (562 to 774 °C), and display geochemical similarity with the Aishan granitoids. Systematic variations of zircon Hf, Yb/Gd, Th/U and Ce/Sm suggest that fractional crystallization of hornblende played a significant role in the formation of the late dikes. The LSFDs originated from the Neoarchean-Paleoproterozoic lower crust of the NCC with heterogeneous involvement of lesser amounts of mantle materials than the early dikes, consistent with weak crust-mantle interaction during the waning stage of lithospheric thinning. In the LSFDs, the granodiorite and monzogranite porphyries are broadly coeval (123–118 Ma) with large scale gold mineralization in the area as also favored by the high zircon Ce4+/Ce3+ ratios. Our study also provides new insights into the formation of gold deposits. Graphical abstract Unlabelled Image Highlights • Two distinct pulses of Cretaceous felsic dike emplacement in the Jiaobei Terrane • Early stage emplaced at 131-127 Ma with magma sourced from Paleoproterozoic lower crust • Late stage formed at 123-116 Ma with magma source from Neoarchean-Paleoproterozoic crust • High zircon Ce4+/Ce3+ and EuN/Eu N * ratios reflect oxidized conditions with potential to generate metallic mineralization. [ABSTRACT FROM AUTHOR]

The Machangqing Cu-Mo-dominated polymetallic deposit is a porphyry-skarn-epithermal Cu-Mo (-Au) metallogenic system located in the middle part of the Jinshajiang–Ailaoshan alkaline porphyry metallogenic belt. The skarn mineralization of the Machangqing deposit mainly occurs along the contacts between the alkalic porphyry intrusions and the surrounding Lower Ordovician Xiangyang Formation rocks. We present LA-ICP-MS U-Pb ages and trace element data for titanite from the Machangqing deposit in order to investigate the origin of this deposit. Based on mineral textures and assemblages, two types of titanite are recognized in Machangqing: magmatic titanite (Type I) from the granite porphyry and hydrothermal titanite from the mineralized skarn. The coarse-grained magmatic titanite is euhedral and occurs as discrete grains in the interstices of feldspar, quartz and biotite, whereas fine- to medium-grained hydrothermal titanite crystals (Type II) are euhedral to subhedral and occur in association with skarn minerals such as garnet, pyroxene and magnetite. Magmatic titanite has lower FeO, Al 2 O 3 , F and Nb/Ta but higher TiO 2 , Th/U, HFSEs and Lu/Hf than hydrothermal titanite. The magmatic titanite has higher LREE/HREE ratios and total REE contents with stronger negative Eu anomalies than its mineralized skarn counterpart. Trace elemental characteristics of hydrothermal titanite in Machangqing are consistent with relatively low F contents and oxygen fugacities when compared to the neighboring Beiya gold-dominated polymetallic deposit in the same metallogenic belt. The weighted average 206 Pb/ 238 U age of 34.3 ± 1.2 Ma of hydrothermal titanite is within error but slightly younger than the age of magmatic titanite (37.5 ± 4.1 Ma), indicating that the skarn mineralization followed the emplacement of the granite porphyry and was broadly coeval with the porphyry mineralization. The porphyry and skarn types of mineralization at Machangqing were formed from the same metallogenic system. Different ore-forming conditions, such as oxygen fugacities and F contents, might be responsible for different metal enrichments at the Machangqing and Beiya deposits. [ABSTRACT FROM AUTHOR]

The Zhonggu ore field is located in the southern Ningwu volcanic basin, the largest iron ore district within the Middle–Lower Yangtze River Metallogenic Belt (MLYRMB) of eastern China. This area has produced more than 2000 Mt of iron ore although comparatively little research has been done on the ore-bearing intrusions in this region despite the significance of the mineralization in this area. This in turn means that the petrogenesis and the links between these intrusions and the metallogenesis in this area remain unclear. This study focuses on the six intrusions that are associated with almost all of the iron deposits within the Zhonggu ore field, namely the Gushan porphyritic gabbrodiorite, the Longshan gabbrodiorite, the Hemushan diorite, the Baixingshan diorite, the Zhongjiu diorite and the Taipingshan monzonite. All of these rocks are either high- to medium-K and calc-alkaline or are shoshonitic, although the former dominates over the latter. Zircon laser ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS) U–Pb dating yielded ages of 132.6 ± 1.6 to 131.6 ± 1.6, 130.7 ± 2.2 to 129.4 ± 1.9, 131 ± 2.0, and 132.3 ± 2.1 Ma for intrusions associated with the Longshan, Taipingshan, Baixiangshan and Zhongjiu deposits, respectively, indicating that all of these intrusions were emplaced in the Early Cretaceous (132.6–129.4 Ma). This magmatism and mineralization was contemporaneous with the second stage (135–127 Ma) of magmatic activity that has been documented elsewhere within the MLYRMB. The mineralized intrusions associated with the Zhonggu iron ore field have similar chondrite-normalized rare earth element (REE) and primitive mantle-normalized multi-element variation patterns that are characterized by light REE (LREE) and light ion lithophile element (LILE; Rb, Ba, K, and Sr) enrichments and heavy REE (HREE) and high field strength element (HFSE; Nb, Ta, Zr, and Hf) depletions. These intrusions also have total REE (ΣREE) concentrations that are consistent with the evolution of the magma from mafic-intermediate to felsic. The magmas that formed these intrusions were derived from an enriched region of the mantle and underwent contamination by the assimilation of continental crustal or lithospheric material. The magmatism within the Zhonggu iron ore field formed during an Early Cretaceous period of lithospheric thinning and extension. In addition, the arc affinities of the intrusions in this region indicative of a relationship to the subduction of the Paleo-Pacific Plate, a process that was most likely the main factor in the generation of the mineralization within the MLYRMB. The Fe mineralization-related intrusions in the study area are also distinctly different from intrusions in this region associated with Cu–Au mineralization, most likely as a result of the heterogeneous distribution of slab-derived fluids in this period over time. This research also highlights the exploration potential of this region, indicating that the 132–129 Ma monzonites and diorites in this area and beyond should be considered prime targets for Fe exploration but are also unlikely to be related to Cu–Au mineralization. [ABSTRACT FROM AUTHOR]

[Display omitted] • Six types of pyrite formed in two overprinting gold-mineralizing events. • Monazite U-Pb dating constrains the age of early mineralization to ca. 429 Ma. • Distinct δ34S values suggest early metasedimentary and late magmatic origin of sulfur. The Tanjianshan goldfield is the most important gold producer in the North Qaidam, NW China. Genesis of gold deposits in Tanjianshan is enigmatic, primarily because of uncertainties as to timing, mineralization processes and fluid sources. We investigate these uncertainties through a comprehensive study of the texture and geochemistry (LA-MC-ICPMS trace elements and sulfur isotopes) of pyrite and in-situ U-Pb dating of monazite from the Qinglonggou gold deposit. Six types of pyrite with distinct textures, trace element contents and sulfur isotopes have been identified, and provide constraints on two overprinting gold-related hydrothermal events. Stage I consists of Py1, occurring as veinlets parallel to S1 deformation in a schist, is characterized by extremely low Co/Ni ratios with high contents of Ni, and high δ34S values (+14.9 ‰ to +16.1 ‰), and were likely derived from metamorphism of the sedimentary strata in the Tanjianshan and Wandonggou Group. In stage II, Py2 occurs in the pyrite-quartz veins that cut Py1 veinlets. They have similar δ34S (+13.1 ‰ to +17.8 ‰) to Py1, indicating that sulfur was likely derived from the dissolution of Py1. The stage I and II veins formed during an early gold pre-concentration event, which is constrained at 429.1 ± 5.9 Ma by in-situ U-Pb dating of monazite that coexists with Py1. Stage III includes Py3 and Py4 which occur in the altered carbonaceous schist and accompanying quartz veins. Trace metals are highest in Py3 (Ag, Au, Sb, and Bi) which represent the most economic ore stage in the deposit, whereas the following Py4 shows low concentrations of most trace elements due to abundant Py3 precipitation. In contrast, trace elements contents increase in Py5 to similar levels as those seen in Py3, suggesting a new pulse of fluid in stage IV. Minor Py6 grains precipitated in the youngest quartz-calcite veins associated with stage V, and contain low concentrations of trace elements. The δ34S values of Py3 (+5.2 ‰ to +6.0 ‰) and Py4 (+4.2 ‰ to +6.1 ‰) are within the range of magmatic sulfur, suggesting a dominantly magmatic source. The δ34S values increase from Py3-4 to Py5 (+6.3 ‰ to +7.4 ‰), and to Py6 (+8.7 ‰ to +9.6 ‰), probably due to increasing contribution from the host rocks, as well as decreasing f O 2 , through incremental fluid-rock interaction. Stages III and IV represent a late gold-mineralizing event during Late Paleozoic to Early Mesozoic, while stage V is post-mineralization. The overprinting gold pre-concentration and mineralization events in the Tanjianshan goldfield correspond to orogenic evolution of the Proto-Tethys Ocean and Paleo-Tethys Ocean, respectively. [ABSTRACT FROM AUTHOR]

There is significant debate regarding the mineralization ages of the East Kounrad, Zhanet and Akshatau W-Mo deposits of Central Kazakhstan, and the petrogenesis and tectono-magmatic evolution of the granites associated with these deposits. To address these issues, we present molybdenite Re-Os dating, zircon U-Pb dating, whole rock geochemistry as well as Sr-Nd-Pb and zircon O-Hf isotopic analyses on the pre-mineralization and ore-forming granites. U-Pb dating of zircons from pre-mineralization granitic rocks yield Late Carboniferous ages of 320–309 Ma, whereas ore-forming granites have Early Permian ages of 298–285 Ma. Molybdenite Re-Os isotopic data indicate a mineralization age of ~ 296 Ma at East Kounrad, ~ 294 Ma at Akshatau and ~ 285 Ma at Zhanet. The pre-ore and ore-forming granites are high-K calc-alkaline, metaluminous to slightly peraluminous I-type granites. The pre-mineralization granites are relatively unfractionated, whereas the ore-forming granites are highly fractionated. The fractionating mineral phases are probably K-feldspar, apatite, Ti-bearing phases and minor plagioclase. The pre-mineralization and ore-forming rocks are characterized by similar Sr-Nd-Pb-Hf-O isotopic compositions (( 87 Sr/ 86 Sr) i = 0.70308–0.70501, ε Nd (t) = − 0.5 to + 2.8, 207 Pb/ 204 Pb = 15.60–15.82, zircon ε Hf (t) = + 1.2 to + 15.6 and δ 18 O = + 4.6 to + 10.3‰), whole rock T DM C (Nd) (840–1120 Ma) and zircon T DM C (Hf) (320–1240 Ma). The isotopic characteristics are consistent with a hybrid magma source caused by 10–30% assimilation of ancient crust by juvenile lower crust. The geochronology and geochemistry of these granites show that the Late Carboniferous pre-mineralization granitic rocks formed during subduction, whereas the Early Permian ore-forming, highly fractionated granite probably underwent significant fractionation with a restite assemblage of K-feldspar, apatite, Ti-bearing phases and minor plagioclase and developed during collision between the Yili and Kazakhstan terranes commenced at the latest Late Carboniferous. [ABSTRACT FROM AUTHOR]

Zircon U–Pb ages of high Mg dioritic dikes in the Mesoproterozoic Kawabulake Group in the Eastern Tianshan area, NW China indicate that they were emplaced in the Early Carboniferous at 353–348 Ma. The dikes consist of medium-grained plagioclase and hornblende with minor clinopyroxene and trace quartz. They are characterized by intermediate SiO 2 (60–62 wt.%), low TiO 2 (0.63–0.71 wt.%), relatively high Al 2 O 3 (15.1–15.8 wt.%) and MgO contents (3.45–4.15 wt.%) with Mg# generally higher than 56 (56–59). The geochemistry of the high Mg diorites suggest they were formed by similar magmatic processes to sanukitoid high Mg Andesites such as those of the Setouchi volcanic belt, Japan. Zircons from the high Mg dioritic dikes have ε Hf( t ) values of −6.8 to +14.5. The dominantly positive values suggest a juvenile source, whereas the small number of negative values suggests mature components were also incorporated into the source. Similarly, the positive ε Nd( t ) values (0 to +2.2) are interpreted to reflect a juvenile source whereas the negative values of (−5.2 to 0) suggest participation of old crustal rocks in the petrogenesis of the diorites. The variable ε Hf( t ) and ε Nd( t ) values suggest that the mature material was assimilated during magma ascent rather than in the mantle wedge which would result in more uniform values. Mass balance calculations suggest that the dioritic dikes were derived from sources composed of approximately 97% juvenile mantle-derived material and 3% sediment. Petrographic, elemental, and isotopic evidence suggest that the dioritic dikes were generated by partial melting of depleted mantle that migrated into the shallow crust where it assimilated older sedimentary rocks of the Mesoproterozoic Kawabulake Group. [ABSTRACT FROM AUTHOR]

Early Cretaceous granitic rocks are widespread in the southern Great Xing'an Range (SGXR) in the eastern part of the Central Asia Orogenic Belt where they have been interpreted to have formed by remelting of juvenile materials derived from a depleted mantle source. We present new U-Pb ages, geochemistry and Sr-Nd-Hf-O isotopic data for ~140 Ma granitic rocks from the Haobugao area. The Xiaohanshan (XHS) quartz monzonite porphyry formed at 140 ± 2 Ma, the Wulanba (WLB) biotite granite formed at 142 ± 2 Ma, and the Wulanchulute (WLCLT) granite formed at 139 ± 2 Ma. They are A-type granites characterised by enrichment of light rare earth and high field strength elements. Based on the geochemistry and Sr-Nd-Hf-O isotope data, the quartz monzonite porphyry with elevated δ18O (6.6‰–7.4‰), high εNd(t) (5.8) and high εHf(t) (5.0–8.4) formed by the partial melting of juvenile material ultimately derived from depleted mantle which had been modified by melts derived from sediment on the downgoing slab. The biotite granite and granite with mantle-like δ18O (4.6‰–6.5‰, one value of 2.7‰), positive εNd(t) (1.4–1.8) and high εHf(t) (3.6–9.4) formed from partial melting of juvenile material derived from depleted mantle. The one low δ18O value from the biotite granite is probably the result of post magmatic alteration. The geochemical data suggest that the granitic rocks of the Haobugao area were not contaminated by older crust and formed in an extensional environment related to Paleo-Pacific oceanic slab rollback. [Display omitted] • Granitic rocks in Haobugao area are A type granites and formed at ~140 Ma. • Coeval Early Cretaceous granitic rocks in the SGXR have different sources. • Evolution of the Early Cretaceous granitic rocks in the SGXR are constrained. [ABSTRACT FROM AUTHOR]