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The article discusses the use of Hf isotopes from detrital and igneous zircon to understand the tectonic evolution of the Central Gneiss Belt in the Grenville Province. It highlights the challenges in using isotopic data to determine allochthoneity and emphasizes the need for detailed mapping and further studies in the area. The authors caution that while isotopic data are valuable for understanding pre-orogenic crustal distribution, they may not provide reliable information on tectonostratigraphy. The complexity of the region's tectonic history limits the ability of isotopic data to determine the allochthoneity of specific units. [Extracted from the article]

In a recent paper presenting 30 new Hf isotope analyses for orthogneisses from the Grenvillian Central Gneiss Belt in Ontario, Slagstad et al. (Slagstad, T., Easton, R.M., Huyskens, M., and Culshaw, N. 2024. Complementarity of Hf isotopes from detrital and igneous zircon: an example from the Central Gneiss Belt, Grenville Province, Ontario. Canadian Journal of Earth Sciences, 61: 19) suggested that these new data "may serve as a basis for some cautionary notes on the application of isotopic data alone to distinguish allochthonous from parautochthonous rocks". These "cautionary notes" evidently arise from the poor fit of the new Hf isotope data to these authors' expectations based on published work. However, we show that the new data are in complete agreement with our own published tectonic maps, based on Nd isotope mapping supported by other available geological evidence. Far from serving as the basis for "cautionary notes" about our use of Nd isotope mapping, the new data completely validate our approach. On the other hand, we show that the mantle model used by Slagstad et al. (2024) to calculate Hf crustal formation ages was based on erroneous old data, and does not yield realistic Hf model ages for Precambrian gneisses. Therefore, we propose a more robust model, based on applying the principles of DePaolo's Nd isotope model to Hf mantle evolution. We term the resulting Hf ages TDP model ages and show that they yield realistic crustal formation ages for the Ontario Grenville Province. [ABSTRACT FROM AUTHOR]

Combined U–Pb and Hf isotopic analysis of detrital and igneous zircon provides information about variations in crustal addition versus reworking through time. However, whereas detrital zircon data from only a few samples can provide information about extended periods of orogenic activity, this approach lacks the geological context that comes with studying igneous zircon and may not record mid- and deep-crustal sources or sources isolated from sites of deposition. Conversely, igneous zircon is likely to miss sources that were removed by later tectonic activity, but which may be preserved in the detrital record. The Central Gneiss Belt of the southwest Grenville Province in Ontario has a relatively well-understood orogenic architecture and records active-margin growth and reworking between ca. 1900 and 1200 Ma. We present U–Pb and Hf isotope data of zircon from 30 orthogneiss samples ranging in age from ca. 1750 to 1250 Ma, covering all tectonostratigraphic levels of the Central Gneiss Belt. As expected, the detrital and igneous datasets display many of the same overall features, such as crustal growth along the southwest Laurentian active margin; however, there are also some distinct differences. In particular, sedimentation appears to have taken place near the active margin, with little or no input from distal inboard sources, thus missing this significant component of reworked crust. This study highlights the need for a combination of detrital and igneous samples to provide the most complete picture of long-lived accretionary orogenic systems. [ABSTRACT FROM AUTHOR]

The Kulun region is located in the eastern Bainaimiao arc belt on the southeastern margin of the Central Asian Orogenic Belt (CAOB), adjacent to the North China Craton (NCC) to the south. This region records the closure of the Paleo-Asian Ocean during the Paleozoic to early Mesozoic and is key to study the tectonic evolution of the northern margin of the NCC. We conducted zircon U-Pb geochronology and Hf isotope analysis of volcanic-sedimentary and intrusive rocks in the Kulun region. The volcanic-sedimentary rocks were previously assigned an early Carboniferous age, but include volcanic rocks with ages of 267–266 Ma and sedimentary rocks with youngest detrital zircon age peaks of 265–244 Ma, which were intruded by a granite with an age of 242 Ma. This indicates that these rocks are actually middle Permian to Middle Triassic in age (267–242 Ma) and correspond to the Qingfengshan and Liujiagou formations. Moreover, two volcanic rock samples have high εHf(t) values (+1.6 to +16.1) and relatively young two-stage Hf model ages (1095–327 Ma), indicating their sources associated with the CAOB. The age spectra and Hf isotopic characteristics of detrital zircons from the sedimentary rocks suggest that, during the middle Permian to Middle Triassic, the sedimentary provenance in the Kulun region was mainly the CAOB. However, by the Early Jurassic, the provenance changed to the NCC (i.e., the Inner Mongolia Paleo-uplift, IMPU). This result, combined with the development of a series of conglomerates on the northern margin of the NCC in the Late Triassic (i.e., Xingshikou, Xiaoyingzi, and Xiaohekou formations), indicates the Kulun region experienced an abrupt change in paleogeography during the Late Triassic, with the IMPU undergoing significant uplift and thus becoming the main sediment source in the Kulun region. Based on the Late Triassic alkaline igneous belt (235–215 Ma) in the IMPU, we speculate that this uplift was caused by detachment of the southward-subducting Paleo-Asian oceanic plate, which occurred in a post-orogenic extensional setting. The boundary between the NCC and CAOB (i.e., the Bainaimiao arc belt) in the Kulun region is defined by the newly identified Paleoproterozoic granites (1.8 and 1.6 Ga) and our zircon geochronology and Hf isotope data. [ABSTRACT FROM AUTHOR]

The Lijia Sn deposit, located in northeastern Guangxi Zhuang Autonomous Region of south China, occurs on the eastern margin of the Yuechengling granite batholith. The Sn deposit contains quartz vein type and greisen type ores and is spatially associated with the medium-coarse-grained biotite granite and the fine-grained tourmaline-bearing biotite granite. LA-ICP-MS zircon U-Pb dating gave an emplacement age of 431.7 ± 2.5 Ma for the medium-coarse-grained biotite granite and of 430.2 ± 2.4 Ma for the fine-grained tourmaline-bearing biotite granite. LA-ICP-MS cassiterite U-Pb dating yielded Tera-Wasserburg lower intercept ages of 429.1 ± 3.4 Ma and 425.7 ± 3.3 Ma for the quartz vein type and greisen type ores, respectively. The ages demonstrate near coeval Caledonian granitic emplacement and Sn mineralization events that have been considered uncommon in south China. Both granites might be derived from partial melting of the Paleoproterozoic basement, as evidenced from zircon ɛHf(t) values of −3.13 to −10.31 and TDM2 from 1627 Ma to 2134 Ma. Three different types of tourmalines have been identified, including (1) tourmaline in quartz–tourmaline nodules in the fine-grained tourmaline-bearing biotite granite (Tur 1), (2) tourmaline in quartz veins (Tur 2a), and (3) tourmaline in greisen (Tur 2b). Most of the tourmalines belong to the alkali group and the schorl-dravite solid-solution series. The hydrothermal tourmalines of Tur 2a and Tur2b showed similar δ11B values to those of the Tur 1 tourmalines in the fine-grained tourmaline-bearing biotite granite, suggesting ore-forming materials derived from granitic magmas. The hydrothermal tourmalines of Tur 2b had slightly lower δ11B values than Tur 1 and Tur 2a tourmalines as a result of progressive 11B depletion during early tourmaline crystallization. [ABSTRACT FROM AUTHOR]

The McDonald Islands, together with Heard Island and the Kerguelen Archipelago, are volcanic islands on the mostly submerged Kerguelen Plateau, and the products of the long‐lived Kerguelen mantle plume (at least 130 Myr; Coffin et al., 2002, https://doi.org/10.25919/jw5f‐ad35). The first multibeam bathymetry data acquired around the Heard and McDonald islands reveal > 70 sea knolls surrounding the McDonald Islands and three sea knolls north of Heard Island. Rocks dredged from McDonald Islands sea knolls include fresh vesicular phonolitic lavas, phonolitic obsidian, phonolitic pillow fragments, and one basanite. These are the first phonolites sampled from the seafloor on the Kerguelen Plateau. Dredging of one sea knoll north of Heard Island recovered basaltic lavas. Lavas from the sea knolls are young, returning 40Ar/39Ar plateau ages of 73.7 ± 15.1 ka to 7.0 ± 2.7 ka for McDonald Islands sea knoll phonolites and 9.0 ± 1.3 ka for the Heard Island sea knoll. We define a new magma series, the McDonald Series, characterized by low εHf (−3.9 to −4.4) and lower Δ207Pb/204Pb (4.5–4.8) and Δ208Pb/204Pb (79–85) than all other lavas on the Kerguelen Plateau. This newly defined series is the product of a relatively young (Pleistocene‐Holocene) phase of volcanism produced by a distinct component of the Kerguelen mantle plume. We propose that McDonald Series phonolites together with 53.4 Ma lavas previously dredged from Ninetyeast Ridge provide evidence for zonation of the Kerguelen mantle plume. Plain Language Summary: Heard Island and the McDonald Islands are active volcanic islands in the southern Indian Ocean that together with the Kerguelen Archipelago were produced by the activity of the long‐lived Kerguelen mantle plume. We dredged lavas from four newly identified sea knolls around the islands. Our geochemical and geochronological analyses of samples from the dredges revealed that the sea knolls around the McDonald Islands are mainly young phonolites of different isotopic compositions from those of Heard Island and the Kerguelen Archipelago. Our new results allow us to distinguish two lava series, the McDonald Series and the Heard Series and provide isotopic evidence for the chemical zonation of the Kerguelen mantle plume since 53.4 Ma. Key Points: High resolution bathymetry obtained around the McDonald Islands on the Kerguelen Plateau reveals > 70 sea knolls for the first timeNewly determined ages and compositions of McDonald Islands sea knolls reveal they are mainly young (<89 Kyr) phonolitic lavasHf and Pb isotopic compositions of McDonald Islands sea knolls provide evidence for compositional zonation of the Kerguelen plume [ABSTRACT FROM AUTHOR]

[Display omitted] • We present new zircon U-Pb, Hf, O isotopes from the Paleoproterozoic Karrat Group. • With provenance analysis of Karrat Group and Rinkian fold belt supracrustal rocks. • Zircon Hf isotopes identify new, abundant ca. 2.15–1.9 Ga juvenile magmatism. • Karrat Group sourced dominantly from orogenies involving the Rae craton. We use zircon U-Pb, Hf and O isotopes to constrain the depositional ages and provenance of metasedimentary rocks of the Paleoproterozoic Karrat Group of West Greenland and to understand the tectonic processes leading to basin development on the eastern Rae craton. An older supracrustal assemblage (Qeqertarssuaq complex) deposited after ca. 2.6 Ga is separated by an unconformity with a younger supracrustal assemblage (the Karrat Group). The Qaarsukassak Formation at the base of the Karrat Group was deposited after ca. 2.0 Ga, with dominantly Archean age modes. The youngest siliciclastic rocks (Nûkavsak and Mârmorilik formations) in the Karrat Group have maximum depositional ages ranging from ca. 1980 to 1950 to 1900 Ma and contain dominant detrital zircon age modes between ca. 2.50 and 1.93 Ga. A ca. 1.92 Ga supracrustal assemblage referred to as the northern domain (Karrat Group, sensu lato) is geographically separated from the Karrat Group (sensu stricto) by the Prøven igneous complex. The stratigraphy and detrital zircon profiles are compared to broadly coeval sedimentary units on the Rae craton and a unifying model of their deposition is presented. The Rae craton is the dominant detritus source; initially these sources were mostly local, changing to a mix of local and distal sources including the western Rae craton. The tectonic setting of the Karrat basin transitioned from extensional to convergent to collisional during its basin evolution, reflecting Wilson cycle phases within an epeiric sea. Accordingly, zircon Hf isotopes in our dataset track the evolution of the opening and closing of the Manikewan Ocean. Detrital zircon Hf isotopes in our dataset reveal a greater proportion of juvenile detritus (especially ca. 2.15–1.95 Ga) than is known from the currently exposed crustal record, pointing to the importance of the detrital zircon record for understanding Paleoproterozoic crustal and tectonic evolution. [ABSTRACT FROM AUTHOR]

Research on the geological process of the Xing'an -- Mongolia Orogenic Belt has attracted the attention of scholars both domestically and internationally. Its genesis and tectonic location may help revealing the geological processes asscoaited with the evolution of the Xing'an -- Mongolia Orogenic Belt. This study focuses on the development of the Permian granitic complex in Jielin Ranch, and we conduct systematic geological, petrographic, zircon U-Pb chronology, Hf isotope, and geochemical tracing of rock elements for evidence. The results show that the granitic complex is mainly composed of monzogranite and syenogranite, which obtained zircon U-Pb ages of 291.1 ± 1.1 Ma and 260.8 ± 1.1 Ma, respectively. The monzogranite and syenogranite are all acidic and aluminum rich rocks, and the monzogranite is a potassium rich, high potassium calcium alkaline rock series with relatively low REE content, high degree of fractionation, and insignificant europium anomalies, enriched with LILE (Rb, Th, U, K), deficient elements such as Ba, Sr, Nb, Ti, and P, εHf(t) values are from +4.1 to +7.0 (TDM2=1130-920 Ma). Geochemistry shows that the monzogranite belongs to high fractionation of I-type granite, which formed in a subduction-compressional or extension tectonic environment, and Middle Neoproterozoic lower crust rocks as the major source material of magma. The syenogranite is a potassium high potassium transitional rock series with a high rare earth content (214 x 10-6~325 x 10-6), low LREE/HREE (2.54-6.41), δEu (0.04-0.15) and the typical "four component effect" fractionation mode is enriched in large ion lithophilic elements such as Rb, Th, K, and strongly depleted in elements such as Ba, Sr, Nb, Ta, Ti, P, εHf(t) values are from +4.2 to +8.6 (TDM2=738-1228 Ma), suggesting the characteristics of an "A2 type" granite. The magma originated from partial melting of the lower crust of the Middle and Neoproterozoic with the participation of mantle derived melts, and was formed in a back-arc extensional environment. This suggests that the study area experienced a subduction-compressional or extension tectonic environment during the early Permian and a brief backarc extension process in the late Permian. [ABSTRACT FROM AUTHOR]

This study presents U-Pb zircon ages and Lu-Hf zircon isotope data for Cretaceous-Paleocene plutonic rocks along a W-E transect in northwestern Mexico. These data are combined with tectonic reconstruction that restores Late Cenozoic extensional deformation and shows the position of magmatism at 36 Ma. Zircon U-Pb ages results span from 142 to 58 Ma and demonstrate that the continental arc migrated northeastward at 1–2.5 km/Myr. These rates are slower than previously interpreted, but consistent with landward arc migration rates observed in the Andes. Weighted mean initial epsilon hafnium (εHf(t)) values of plutonic rocks along the transect range from + 8.8 to −9.1. The heterogeneity in the zircon εHf(t) is spatially related to the pre-Cretaceous basement provinces that the intrusive rocks were emplaced into. Zircon εHf(t) values of western Baja California display positive values ranging from + 8.8 to + 2.6 suggesting they were formed from a moderately depleted mantle and were emplaced into the Guerrero-Alisitos-Vizcaino terrane. Zircon εHf(t) values in the eastern part of Baja California and most of Sonora are heterogeneous ranging between −0.7 and −9.1 and may be formed from a relatively slightly more evolved mantle source and end up more evolved after crustal assimilation of metasediments. Zircon εHf(t) values ranging from + 8.7 to + 2.9 in Chihuahua are consistent with a depleted-mantle derived melt and assimilation of Grenville lithospheric province. Our results highlight how Hf isotopic signatures help to constrain the pre-Cretaceous basement configuration in northwestern Mexico despite the few exposed outcrops along the transect. [ABSTRACT FROM AUTHOR]

Xenoliths recovered from the post-Variscan Bode dike system of the eastern Harz Mountains provide evidence for the existence of an Early Devonian magmatic arc system hidden beneath very low-grade metasedimentary rocks of the Rhenohercynian Zone, but also for Late Carboniferous–Early Permian crust reworking. This interpretation is based on petrographic observations and whole-rock geochemical analyses of granite xenoliths, in addition to results of zircon U–Pb dating and Hf isotope analyses. Zircon grains recovered from variably deformed granite xenoliths yield ages between 419 and 393 Ma, interpreted to reflect the timing of granite intrusion. Rare zircon xenocrysts of Archean (ca. 2.92–2.65 Ga) and Proterozoic age (ca. 1.5 to 0.56 Ga), all with subchondritic εHf420 Ma values (− 0.8 to − 5.5) indicate reworking of older crust. Compilation of age-Hf isotope data further suggests that the pre-Variscan granitoids beneath the Harz Mountains belong to the same magmatic arc system exposed widespread in the adjacent Mid-German Crystalline Zone, and interpreted to result from NW-ward subduction of the Rheic Ocean beneath Avalonia-Baltica. Zircon in xenoliths with granophyric texture yields ages at 400 Ma and 295–310 Ma, indicating re-melting of Devonian granitoid basement during post-Variscan rift-related magmatism, immediately prior to Bode dike intrusion. Left: Late Devonian intrusion of magmatic arc granites during NW-ward subduction of the Rheic ocean beneath Avalonia-Baltica. Right: Formation of the Bode dike system and Harz granites during Late Carboniferous-Permian extension. [ABSTRACT FROM AUTHOR]

HafAn is a new R-language script for recalculation, statistical treatment and graphical presentation of the Hf isotopic data from whole-rock samples or, more commonly, obtained in situ (e.g. by LA MC ICP-MS) from igneous, metamorphic and detrital zircon. Besides the recalculation of the present-day Hf isotopic ratios to initial ones, epsilon values and various variants of model ages, it allows presentation of such univariate data in the form of histograms, boxplots, stripplots and violin plots. Arguably the most telling and sophisticated way of displaying the Hf isotopic data are the Hf isotopic growth (age-176Hf/177Hf or epsilon Hf) diagrams. The HafAn has been designed as a plugin module for the Geochemical Data Toolkit (aka GCDkit), a well-established system for interpretation of the whole-rock geochemical data. This approach potentially allows interpretation (and plotting) of the Hf isotopic data jointly with the rest of the chemical and/or isotopic signature, as well as merging or overplotting several datasets on a single diagram. Moreover, R/GCDkit contains a plethora of additional statistical tools that can be newly applied to the Hf isotopic data as well. Our HafAn also profits from a wide palette of the file formats available for reading data input, as well as exporting results and graphical output. The HafAn plugin, together with all the GCDkit-family tools, can be downloaded from https://gcdkit.org. [ABSTRACT FROM AUTHOR]

Abstract The McDonald Islands, together with Heard Island and the Kerguelen Archipelago, are volcanic islands on the mostly submerged Kerguelen Plateau, and the products of the long‐lived Kerguelen mantle plume (at least 130 Myr; Coffin et al., 2002, https://doi.org/10.25919/jw5f‐ad35). The first multibeam bathymetry data acquired around the Heard and McDonald islands reveal > 70 sea knolls surrounding the McDonald Islands and three sea knolls north of Heard Island. Rocks dredged from McDonald Islands sea knolls include fresh vesicular phonolitic lavas, phonolitic obsidian, phonolitic pillow fragments, and one basanite. These are the first phonolites sampled from the seafloor on the Kerguelen Plateau. Dredging of one sea knoll north of Heard Island recovered basaltic lavas. Lavas from the sea knolls are young, returning 40Ar/39Ar plateau ages of 73.7 ± 15.1 ka to 7.0 ± 2.7 ka for McDonald Islands sea knoll phonolites and 9.0 ± 1.3 ka for the Heard Island sea knoll. We define a new magma series, the McDonald Series, characterized by low εHf (−3.9 to −4.4) and lower Δ207Pb/204Pb (4.5–4.8) and Δ208Pb/204Pb (79–85) than all other lavas on the Kerguelen Plateau. This newly defined series is the product of a relatively young (Pleistocene‐Holocene) phase of volcanism produced by a distinct component of the Kerguelen mantle plume. We propose that McDonald Series phonolites together with 53.4 Ma lavas previously dredged from Ninetyeast Ridge provide evidence for zonation of the Kerguelen mantle plume.

Abstract With the development of detrital zircon U–Pb ages and Hf isotope analysis as conventional sedimentological research methods, a large number of studies have been conducted in the Tarim, West Kunlun, Tajik, Pamir and Tianshuihai regions and abundant data have been accumulated. Summarizing these data to characterize sedimentary units and source regions is more important than local studies of specific geological epochs; therefore, we compiled a database of detrital zircon U–Pb ages and Hf isotope analyses from the Tarim, West Kunlun, Pamir, Tajik and Tianshuihai terranes. The database contains data from 90 papers, including 35,281 individual U–Pb ages and 4,181 Hf isotope analyses. The database records the literature source, petrologic sample information, regional geological information, geographic coordinates and analytical parameters for each data point in as much detail as possible to allow readers to review, process, analyse and use the data. The database relies on the Deep‐time Digital Earth (DDE) platform and uses an open database update system to enable sharing and collaborative building. We encourage other researchers to contribute relevant published data to facilitate wider use.

With the development of detrital zircon U–Pb ages and Hf isotope analysis as conventional sedimentological research methods, a large number of studies have been conducted in the Tarim, West Kunlun, Tajik, Pamir and Tianshuihai regions and abundant data have been accumulated. Summarizing these data to characterize sedimentary units and source regions is more important than local studies of specific geological epochs; therefore, we compiled a database of detrital zircon U–Pb ages and Hf isotope analyses from the Tarim, West Kunlun, Pamir, Tajik and Tianshuihai terranes. The database contains data from 90 papers, including 35,281 individual U–Pb ages and 4,181 Hf isotope analyses. The database records the literature source, petrologic sample information, regional geological information, geographic coordinates and analytical parameters for each data point in as much detail as possible to allow readers to review, process, analyse and use the data. The database relies on the Deep‐time Digital Earth (DDE) platform and uses an open database update system to enable sharing and collaborative building. We encourage other researchers to contribute relevant published data to facilitate wider use. [ABSTRACT FROM AUTHOR]

The stable Zr isotope ratios in zircon yield a novel geochemical tracer that, together with the Lu‐Hf and U‐Pb radiogenic isotope systems, allows for a better understanding of the magmatic evolution of silicate melts. We present a solution‐based procedure for coupled stable Zr, Lu‐Hf and U‐Pb isotope ratio determinations for individual zircons using a 91Zr‐96Zr tracer purified from Hf and a late‐spiking protocol for Zr. This method yields high‐precision Zr and Hf isotope results while maintaining low blank levels for U‐Pb isotope and Lu/Hf ratio determinations. With a two‐fold improvement on the precision relative to previous solution‐based work, we report δ94ZrIPGP‐Zr values (deviation of the 94Zr/90Zr ratio in the sample relative to the IPGP‐Zr reference material) and associated intermediate precisions (2s) for the zircon reference materials 91500, Mud Tank, Plešovice and Penglai of ‐0.041 ± 0.015‰, 0.018 ± 0.013‰, 0.089 ± 0.020‰ and ‐0.117 ± 0.021‰, respectively. Furthermore, this method yields un‐biased δ94ZrIPGP‐Zr and 176Hf/177Hf results for 25‐ng Zr and 0.56‐ng Hf aliquots of the Mud Tank zircon with intermediate precisions (2s) of 0.027‰ and 1.7 ε (parts per ten thousand), respectively. Thus, the presented method is applicable for the analysis of extremely small and rare zircon grains. [ABSTRACT FROM AUTHOR]

Magmatism is a critical component in sustaining hydrothermal convection and metal transport during the formation of volcanogenic massive sulfide (VMS) deposits. Previous studies of magmatic petrogenesis in VMS systems have demonstrated that ore-related volcanic rocks have distinct whole-rock geochemical and isotopic signatures (i.e., high HFSE, REE, Th, εHf-Nd, zircon saturation T) relative to barren volcanic rocks, which supports models of elevated crustal heat flow during periods of ore deposition; however, the petrologic characteristics and intrinsic parameters (e.g., T, fO2) related to these magmatic events in VMS districts remain poorly understood. Arc–back-arc assemblages from the mid-Paleozoic Yukon-Tanana terrane are well-characterized and include the Finlayson Lake VMS district, which is host to several felsic-hosted deposits (e.g., Kudz Ze Kayah, GP4F, Wolverine) that were generated in a peri-Laurentian continental back-arc tectonic setting. In this study, zircon from back-arc and coeval arc rocks in the Yukon-Tanana terrane was used as a proxy for primary magma formation conditions that generated VMS-proximal and VMS-distal stratigraphy. Our results indicate that zircon grains in VMS-proximal environments have unique textural, geochemical, and isotopic characteristics (e.g., low-aspect ratios, greater abundance of zircon-phosphate intergrowths, Th/U > 1, Zr/Hf > 80, Tzrc > 780 °C, εHfi > –7) that are clearly distinguished from zircon in VMS-distal rocks in both the back-arc and arc settings (Th/U < 1, Zr/Hf < 80, Tzrc < 780 °C, εHfi < –7). These signatures correlate to VMS-proximal magmas that were hotter, less fractionated, and contained greater juvenile melt contributions compared to VMS-distal magmas and reflect a series of high-flux magmatic events that directly correspond to the early tectonic development of Yukon-Tanana terrane. Moreover, this study underscores the importance of mineral-scale petrology, geochemistry, and geochronology in defining the primary magmatic conditions that generated VMS-related felsic rocks and highlights the utility of zircon as a prospectivity tool in both grassroots and brownfields VMS exploration. [ABSTRACT FROM AUTHOR]

The Anshan–Benxi area, situated in the northeast of the North China Craton (NCC), is home to not only the oldest rocks in China (~3.8 Ga) but also a diverse range of granitoids dated between 3.8 and 2.5 Ga. The Lianshanguan batholith, covering an area of approximately 250 km2 with an east–west trend, predominantly consists of syenogranites (K2O > 4 wt. % and K2O/Na2O ratios > 1.3). Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U-Pb analyses of the two syenogranites yielded concordant ages of 2541 ± 22 and 2512 ± 13 Ma, respectively. These syenogranites had zircon εHf(t) values ranging from −20 to +4.9 with two-stage Hf model ages (TDM2(Hf)) spanning 3.9–2.7 Ga. Based on petrological, geochemical, and isotopic characteristics, we conclude that the Lianshanguan syenogranites are mainly resulted from the reworking of complicated Eoarchean–Mesoarchean crustal materials, possibly with a small proportion of ~2.7 Ga juvenile crustal materials. When compared with coeval syenogranites from the Northern Liaoning and Western Liaoning–Eastern Hebei areas, ~2.5 Ga syenogranites from the Anshan–Benxi area displayed more complicated TDM2(Hf) ages, hinting at a pronounced late Neoarchean reworking of the Eoarchean to Mesoarchean continental crust (including metasedimentary sources) primarily in the Anshan–Benxi region of the North China Craton. This scenario significantly bolsters the arc–continent collision model. [ABSTRACT FROM AUTHOR]

The Chenar volcanic cone intruded the southeastern part of the Dehaj-Sarduiyeh volcano-sedimentary belt, in the southeast Urumieh-Dokhtar magmatic arc in Iran. The adakitic rocks, with porphyritic texture, mainly consist of rhyodacites and dacites, commonly comprised of phenocrysts of plagioclase, hornblende and biotite, with rare K-feldspar, in a groundmass composed of plagioclase, K-feldspar and quartz. They yielded U-Pb zircon ages of 5.52±0.099Ma, 5.46±0.12Ma, and 6.44±0.12Ma, and radiogenic ɛHf(t) values ranging from +3.1 to +12.7. The whole-rock geochemical analysis of these rocks reveals transitional calc-alkaline to shoshonitic characteristics. The geochemical characteristics of the study rocks, particularly their high Sr/Y (⁓51.6-136.8) at low Y (⁓4.43-16.2ppm) and high La/Yb (⁓28.4-118.4ppm) at low Yb (⁓0.2-1.3ppm), are coherent with a high-silica adakitic signature. The whole-rock positive Eu/Eu* anomaly and zircon Ce/Ce* anomaly reflect the effects of an oxidized magmatic signature, with the rocks of the study area originating from a mantle source. The high-silica adakite geochemical characteristics of the Chenar volcanic cone support formation by partial melting of the modified mantle under the influence of metasomatized subducted oceanic slab in a post-collisional environment. [ABSTRACT FROM AUTHOR]

Unlike oceanic hotspot tracks, continental hotspot tracks are difficult to recognise, although they can provide unique insights into crustal deformation and intraplate magmatism. Here, we present whole‐rock geochemical and Sr–Nd isotope, and zircon U–Pb age and Hf isotope data for a tuff from the E'Xi rift basin in the South China Block. The zircons yielded a 206Pb/238U age of 267.0 ± 2.0 Ma, which coincides with the Roadian–Wordian boundary. The whole‐rock geochemical and Sr–Nd isotope data for the tuff indicate it had a mixed mantle–crust source. The zircon trace element and εHf(t) (−6.32 to +7.06) data are also consistent with such a source. Based on the sedimentological and tectonic history, and the geochronology and geochemistry of the tuff, we propose the tuff erupted in a rift and records the hidden hotspot track of the Emeishan mantle plume beneath the northern SCB. [ABSTRACT FROM AUTHOR]

Active and passive continental rifts are generally attributed to plume and subduction mechanisms, respectively. However, controversy surrounding the role of the two mechanisms continues, especially for the mid-Neoproterozoic rifts in the South China Craton. Here, we use geochemical and zircon Hf isotope data from the craton's rift successions to examine the mechanism of rifting. The compiled geochemical data support the existence of subduction-related magmatic belts along the Jiangnan Orogen and western Yangtze margin of the craton during the mid-Neoproterozoic, consistent with a conventional subduction-related passive rift mechanism. But evidence of asthenospheric upwelling and subsequent lithospheric uplift, metamorphism, volcanism and magma-rich rift infill indicate rifting was active. Compiled zircon εHf(t) values and crustal incubation times suggest a ca. 830–780 Ma transition from advancing to retreating subduction that coincides with rifting across the craton. We therefore propose a subduction-related active rifting model in which the onset of transitionalsubduction triggered mantle convection and plume activity that led to the mid-Neoproterozoic initiation of active rifting in the South China Craton. This suggests a mixed mechanism for rifting rather than two distinct end-members. [ABSTRACT FROM AUTHOR]

The Tibetan Plateau is a key region to understand the evolution of the Tethys Oceans. To better constrain the tectonic evolution of the Proto-Tethys Ocean on the western margin of the Yangtze plate, we present an integrated petrography, geochemistry, and zircon U-Pb-Lu-Hf isotope study on newly recognized early Silurian gabbro and serpentinite rocks from the eastern Yidun terrane of the Tibetan Plateau. Zircon U-Pb dating of the gabbro yields an Early Silurian age of 438.2 ± 2.8 Ma. Zircon εHf(t) values of 5.4 to 8.5 suggest a single-stage model age (TDM1) ranging from 729 to 858 Ma. The gabbros exhibit low total rare earth element abundances but are moderately enriched in the light rare earth elements and the large-ion lithophile elements (e.g. Rb, Ba, and Sr), and display representative negative high-field strength elemental anomalies for Nb, Ta, Zr, and Hf on spidergrams. The gabbro and serpentinites were derived from a depleted mantle-like source made of garnet-spinel lherzolite composition, from a sub-arc mantle wedge that was metasomatized by slab dehydration. Thus, the gabbro and serpentinites record an Early Silurian subduction event of the Proto-Tethys Ocean under the Yangtze plate. Furthermore, this study confirms that the Yidun terrane on the western margin of the Yangtze plate is underlined by a Precambrian crystalline basement. [ABSTRACT FROM AUTHOR]

The Shaolang River metallogenic belt in Inner Mongolia is one of the main lead‐zinc polymetallic belt on the northern margin of the North China Plate. The granodiorites, which are closely coexisting with lead‐zinc veins in deposit, are extensively developed. Previous geochronological research results show that the dikes and veins in the metallogenic belt belong to the products of magmatic hydrothermal activity in the middle Yanshanian, so the genesis of the metallogenic belt deposit is generally considered to be a hydrothermal vein type deposit related to sub‐volcanic dikes. We obtained zircon LA‐ICP‐MS U–Pb ages and Hf isotopic compositions of granodiorites, which are widely distributed in the deposit and were considered to be closely connected with the genesis of the deposits. The zircon U–Pb ages are 419.4 ± 1.4 Ma and 424.5 ± 4.1 Ma for the granodiorites, respectively, and they formed in the late Silurian. The geological and geochemical data indicate that the granodiorites are consistent with the geochemical characteristics of typical adakite. All εHf(t) values of the granodiorites are minus, on the zircon Hf isotope age diagram, εHf(t) are below the evolution curve of chondrite. The two‐stage model ages (tDM2) are 2.45 ~ 2.79 Ga and 1.87 ~ 2.29 Ga, respectively, showing rock‐forming materials mainly derived from the Paleoproterozoic and earlier crustal partial melting, and there may have been mantle‐derived magma underplating of the lower crust. Combining with the previous regional research, it is concluded that the granodiorites were formed during the extinction of the island arc under the background of subduction of the Paleo‐Asian Ocean and North China Craton. Because of the 125 ~ 170 Ma metallogenic age, we concluded that the granodiorites in the ore areas have no obvious relationship with the deposit genesis. However, it provided the advantageous space for the formation of the lead‐zinc veins, it can be regarded as an important prospecting indicator in metallogenic belt. [ABSTRACT FROM AUTHOR]

The Almogholagh Intrusive Complex (AIC) in the central part of the Sanandaj-Sirjan zone (C-SaSZ) includes gabbros to granites. Zircon U-Pb dating of mafic, intermediate, and felsic intrusions yield age of 146 to 141 Ma (Late Jurassic-Early Cretaceous). Bulk chemistry shows a wide range for SiO2 (46.8 to 73.3 wt.%), MgO (0.08 to 8.95 wt.%), and Fe2O3(T) (0.47 to 9.25 wt.%) and also alkali elements ranging from 3.59 to 10.12 wt.%. These rocks are characterized by a high content of large-ion lithophile elements (LILEs; e.g. Rb, U, Th, and K) and LREEs with weak Nb and Ta negative anomalies, showing many similarities to an extensional setting. The 176Hf/177Hf ratios vary from 0.282802 to 0.282985 with positive εHf(t) values from + 1.67 to +10.74 (avg: 7.85). Trace-element and isotope ratios modelling indicate that the AIC mafic-intermediate rocks were generated by partial melting of spinel lherzolite and then underwent considerable crustal contamination. The present work in combination with previous data confirm an extensional tectonic regime for the northern part of the C-SaSZ during the Late Jurassic to Early Cretaceous. Magmatic differentiation with crustal contamination played a fundamental role in the wide compositional range from mafic to felsic types that formed the AIC. [ABSTRACT FROM AUTHOR]

Slab rollback during subduction plays a key role in controlling continental growth at convergent plate boundaries. The dynamics of currently subducting slabs can be precisely constrained using geophysical techniques. In contrast, ancient episodes of slab rollback can be difficult to constrain, yet are critical to unlocking the tectonic evolution of long‐lived orogens such as the Phanerozoic Australian Tasmanides of eastern Gondwana. Recognition of ancient slab rollback relies on the identification of the progressive migration of magmatic arcs. Here, we investigate the timing and isotopic variation of ∼90 km of the trans‐orogen migration of the Carboniferous Bathurst Batholith as a potential indicator of slab rollback. U–Pb–Hf isotopes, combined with a regional zircon Hf isotope data set, suggest that the eastward migration of the batholith over ∼18 Myr, from 340.1 to 322.4 Ma, records a maximum slab steepening rate of ∼0.6–1.2° Myr−1 in a relatively stable trench setting. These results provide a magmatic record of Carboniferous slab rollback and establish a missing link between the long‐lived Lachlan and New England orogens of the eastern Gondwanan Tasmanides. Plain Language Summary: Slab rollback occurs at convergent plate boundaries, which is key to understanding the evolution of subduction processes. However, for ancient subduction zones where the geometry of long since subducted slabs no longer exists, the evolution of slab dynamics remains unclear. Occasionally though, the progressive migration of magmatic trends is observable and provides constraints on slab rollback, which aid in reconstructing the tectonic evolution of long‐lived orogens, such as the Phanerozoic orogens of eastern Australia. Here, we focus on how the unique magmatism of the Carboniferous Bathurst Batholith progressively migrated in the direction of the trench and analyze and interpret the geochronological and geochemical evolution of the batholith to better constrain subduction dynamics. We find that the Bathurst Batholith records the Carboniferous slab rollback of eastern Gondwana and reveals the relationship between the two key orogens of eastern Australia. Thus, the migration of magmatism in convergent settings can be used to track the slab rollback processes and evolution of the long‐lived orogens. Key Points: The Bathurst Batholith is part of a Carboniferous continental arc formed as a result of westward subduction in eastern GondwanaEastward migration of the batholith over ∼18 Myr recorded a maximum slab steepening rate of ∼0.6–1.2° Myr−1 in a stable trench settingThe batholith as a trans‐orogen "missing link" reveals continental arc magmatism extended across the Lachlan and New England orogens [ABSTRACT FROM AUTHOR]

The Caopas sub-volcanic intrusion crops out in the northern area of the Nazas Igneous Province. Due to its extension (∼70 km2), this intrusion is the largest igneous body within this province. At the same time, its location, close to the boundary between the Central terrane and Oaxaquia microcontinent, highlights its relevance to understanding the role that the basement plays in the genesis of the Caopas sub-volcanic intrusion. In this paper we present whole rock geochemical data of major and trace elements, U-Pb ages, Hf isotopes and trace elements in single zircon grains from samples of the Caopas sub-volcanic intrusion (U-Pb zircon age: ∼166.97 ± 0.96 Ma). Geochemical data indicate that the rocks studied are peraluminous (Al/CNK ≥1). The analyzed zircon grains exhibit enriched Hf isotopic compositions (εHf (t) from −1.6 to 2.5), high U/Yb values and negative Eu anomalies, suggesting, along with the geochemical data, that these magmas were formed by significant volumes of crustal melts during their genesis. The Hf model ages in zircon grains are consistent with a Mesoproterozoic crustal source for the magmas that formed the intrusive (∼1023 Ma to ∼1282 Ma), which coincides with ages reported for rocks in the crystalline basement of the area (i.e. the Oaxaquia microcontinent). • U-Pb zircon dating shows Caopas sub-volcanic intrusion emplaced in the Middle Jurassic. • Geochemical and isotopic data suggest magmas derived from continental crust. • Hf model ages indicate Mesoproterozoic Oaxaquia microcontinent as the magma source. [ABSTRACT FROM AUTHOR]

Abstract Slab rollback during subduction plays a key role in controlling continental growth at convergent plate boundaries. The dynamics of currently subducting slabs can be precisely constrained using geophysical techniques. In contrast, ancient episodes of slab rollback can be difficult to constrain, yet are critical to unlocking the tectonic evolution of long‐lived orogens such as the Phanerozoic Australian Tasmanides of eastern Gondwana. Recognition of ancient slab rollback relies on the identification of the progressive migration of magmatic arcs. Here, we investigate the timing and isotopic variation of ∼90 km of the trans‐orogen migration of the Carboniferous Bathurst Batholith as a potential indicator of slab rollback. U–Pb–Hf isotopes, combined with a regional zircon Hf isotope data set, suggest that the eastward migration of the batholith over ∼18 Myr, from 340.1 to 322.4 Ma, records a maximum slab steepening rate of ∼0.6–1.2° Myr−1 in a relatively stable trench setting. These results provide a magmatic record of Carboniferous slab rollback and establish a missing link between the long‐lived Lachlan and New England orogens of the eastern Gondwanan Tasmanides.

The duration and extent of sediment routing systems are intrinsically linked to crustal‐ to mantle‐scale processes. Therefore, distinct changes in the geodynamic regime may be captured in the detrital record. This study attempts to reconstruct the sediment routing system of the Canning Basin (Western Australia) during the Early Cretaceous to decipher its depositional response to Mesozoic‐Cenozoic supercontinent dispersal. Specifically, we reconstruct source‐to‐sink relationships for the Broome Sandstone (Dampier Peninsula) and proximal modern sediments through multi‐proxy analysis of detrital zircon (U–Pb, Lu–Hf and trace elements) and detrital rutile (U–Pb and trace elements). Multi‐proxy comparison of detrital signatures and potential sources reveals that the majority of the detrital zircon and rutile grains are ultimately sourced from crystalline basement in central Australia (Musgrave Province and Arunta region) and that proximal sediment supply (i.e., Kimberley region) is negligible. However, a significant proportion of detritus might be derived from intermediate sedimentary sources in central Australia (e.g., Amadeus Basin) rather than directly from erosion of crystalline basement. Broome Sandstone data are consistent with a large‐scale drainage system with headwaters in central Australia. Contextualization with other broadly coeval drainage systems suggests that central Australia acted as a major drainage divide during the Early Cretaceous. Importantly, reorganization after supercontinent dispersal is characterized by the continuation of a sediment pathway remnant of an earlier transcontinental routing system originating in Antarctica that provided a template for Early Cretaceous drainage. Review of older Canning Basin strata implies a prolonged denudation history of central Australian lithologies. These observations are consistent with the long‐lived intracontinental tectonic activity of central Australia governing punctuated sediment generation and dispersion more broadly across Australia and emphasize the impact of deep Earth processes on sediment routing systems. [ABSTRACT FROM AUTHOR]

The number of subduction zones that facilitated the northward translation of the Anatolide‐Tauride continental terrane derived from Gondwana to the southern margin of Eurasia at the longitude of western Turkey is debated. We hypothesized that if two north dipping subduction zones facilitated incipient collision in western Turkey, a late Cretaceous arc would have formed within the Neotethys and along the southern margin of Eurasia. To determine if an island arc formed within the Neotethys we investigated the sedimentary record of the Central Sakarya basin, which was deposited along the southern margin of Eurasia from 85 to 45 million years ago. Detrital zircon deposited within the lower levels of the Central Sakarya basin (the Değirmenözü Formation) are associated with south to north‐directed paleocurrents and exhibit a unimodal late Cretaceous age peak sourced from isotopically juvenile mantle melts. Zircon maximum depositional ages from the Değirmenözü Formation cluster between 95 and 90 Ma and are 5–10 Myr older than biostratigraphic depositional ages. Between 95 and 80 Ma, a 12‐unit shift from mantle to crustal derived εHf values occurs in the overlying Yenipazar Formation. We explain the absence of Paleozoic, Eurasian‐sourced detrital zircon, the rapid shift from mantle to crustal derived εHf values, and lag time in terms of passive margin subduction within an isolated intra‐oceanic subduction zone, whose island arc was reworked from south to north into the Central Sakarya basin during incipient collision. Thus, widely outcropping late Cretaceous plutonic rocks within Eurasia must have belonged to an additional convergent margin. Key Points: We leveraged the isotopic signature of subducted passive margin to test incipient collision models in northwest TurkeyPassive margin subduction resulted in the development of an isolated intra‐oceanic basinTwo north dipping subduction zones facilitated incipient collision in the region [ABSTRACT FROM AUTHOR]

Open-system magmatic processes are expected to impart various sorts of isotopic heterogeneity upon the igneous rocks they produce. The range of processes under the “open-system” umbrella (e.g., simple two-component mixing, magma mingling, assimilation with fractional crystallization) cannot usually be uniquely identified using data from a single isotope system. The use of bulk-rock, mineral separate and in situ techniques and multiple isotope systems allows the characterization of isotopic variability at different sampling scales, illuminating details of the petrogenesis of a magmatic system. This approach has been applied to granitoids of the Wallundry Suite in the Lachlan Fold Belt, Australia. The Wallundry Suite exhibits variations in mineral assemblage, mineral composition and trends in bulk-rock major and trace element compositions consistent with the involvement of liquid-crystal sorting processes such as fractional crystallization. In situ paired O-Hf isotope data from zircon in six samples show an array indicating the isotopic evolution of the melt phase. Similarly, bulk-rock Sr-Nd-Hf isotope arrays support open-system magma evolution. These data combined with the petrographic observations and major and trace element geochemical variations suggest some form of assimilation-fractional crystallization process in the petrogenesis of the Wallundry Suite. Added complexity is revealed by two observations: 1) the isotopic variations are only weakly coupled to the lithology and major element compositions of the samples; and 2) there are distinguishable differences between the Hf isotope compositions of bulk-rock samples and those of the magmatic zircons they host. To varying degrees the rocks consistently show negative ΔεHfbulk-zrc values (i.e., the bulk-rock compositions have less radiogenic Hf isotope values than their coexisting zircons). The preservation of distinctly low Nd and Hf isotope ratios in an Fe-Ti oxide mineral separate suggests that the bulk-rock vs. zircon discrepancy is caused by the presence of unmelted components derived from a contaminant of continental origin (i.e., a rock with low Sm/Nd and Lu/Hf and thus unradiogenic Nd and Hf). Evidently, a complex interplay of assimilation, crystallization and melt segregation is required to account for the data. This investigation demonstrates that such complexity can, nevertheless, be disentangled through comparison of complementary isotope data at multiple sampling scales.

Abstract The number of subduction zones that facilitated the northward translation of the Anatolide‐Tauride continental terrane derived from Gondwana to the southern margin of Eurasia at the longitude of western Turkey is debated. We hypothesized that if two north dipping subduction zones facilitated incipient collision in western Turkey, a late Cretaceous arc would have formed within the Neotethys and along the southern margin of Eurasia. To determine if an island arc formed within the Neotethys we investigated the sedimentary record of the Central Sakarya basin, which was deposited along the southern margin of Eurasia from 85 to 45 million years ago. Detrital zircon deposited within the lower levels of the Central Sakarya basin (the Değirmenözü Formation) are associated with south to north‐directed paleocurrents and exhibit a unimodal late Cretaceous age peak sourced from isotopically juvenile mantle melts. Zircon maximum depositional ages from the Değirmenözü Formation cluster between 95 and 90 Ma and are 5–10 Myr older than biostratigraphic depositional ages. Between 95 and 80 Ma, a 12‐unit shift from mantle to crustal derived εHf values occurs in the overlying Yenipazar Formation. We explain the absence of Paleozoic, Eurasian‐sourced detrital zircon, the rapid shift from mantle to crustal derived εHf values, and lag time in terms of passive margin subduction within an isolated intra‐oceanic subduction zone, whose island arc was reworked from south to north into the Central Sakarya basin during incipient collision. Thus, widely outcropping late Cretaceous plutonic rocks within Eurasia must have belonged to an additional convergent margin.

The Wenjiaping granite, as one of the few Late Jurassic granites in the Songpan–Garzê fold belt (SGFB), can provide an important clue for comprehensively recognizing the tectonic evolution and mineralization of this belt. In this contribution, we present new age and geochemical data for this pluton to better constrain its petrogenesis and discuss the tectonic and metallogenic implications. LA‐ICP‐MS zircon U–Pb dating shows that the Wenjiaping pluton was emplaced at ~159 Ma. The granite contains minor amphibole, and exhibits slightly peraluminous characteristics (A/CNK = 1.03–1.10) and lower initial Sr–Pb isotope ratios than those of the Liwu Group, which excludes the possibility that the Wenjiaping granite was derived from partial melting of the metasedimentary rock‐dominated Liwu Group as previously suggested. Significantly, high Sr/Y (40.93–54.30), LaN/YbN (39.64–56.64), and K2O/NaO (0.77–1.11) ratios, low MgO (0.47%–0.86%) and Cr (25.1–41.3 ppm) contents, and relatively enriched Sr–Nd–Pb–Hf isotope compositions of the Wenjiaping granite are comparable to those of the Late Triassic adakitic rocks in the SGFB, indicating that they probably share a similar source. Combined with previous researches, we propose that large‐scale detachment of the Jianglang dome caused by post‐collisional lithospheric extension in the SGFB‐induced decompressional partial melting of the Precambrian basement rocks can account for the generation of the Late Jurassic Wenjiaping pluton. In addition, our results also suggest that the Wenjiaping pluton probably cannot supply abundant metal elements for the Liwu‐type Cu‐polymetallic deposits in the Jianglang dome, SGFB. [ABSTRACT FROM AUTHOR]

In the northwestern Korean Peninsula, Cretaceous volcanic rocks are composed of andesite, andesite-dacite and rhyolite intercalated with terrigenous clastic rocks. Zircon grains selected from these rocks are authigenic zircons with obvious crystal edges and oscillatory zoning, their Th/U ratios being generally larger than 0.4 (0.16–2.22), indicating magmatic origin. Most rocks were formed at Early Cretaceous Albian (113–103 Ma) and partially, at late Aptian, Prior to this time magmatism took place at 125 Ma and 135 Ma. All the negative εHf(t) values mean that these magma sources were contaminated by crust materials or derived from enriched mantle. Volcanic rocks belong to calc-alkaline series and partially to peraluminous series with relatively high alkali content. Chondrite-normalized REE patterns display right-lean LREE rich type and Primitive-mantle-normalized REE patterns do obvious negative anomalies in LILE (Ba, Sr), HFSE (Nb, Ta, P, Zr, Ti), but obvious positive anomalies in LIL (Rb, Pb) and HFS (Th, U, Nd). These volcanic rocks were formed in continental arc setting and their geochemical properties being similar to those of arc ADR (normal Island-Arc Andesite-Dacite-Rhyolite) suite rather than those of adakite. In the Late Early Cretaceous, west area of northeastern Asia including western Liaoning, China was in extensional setting but east area of northeastern Asia including northwestern Korean Peninsula, Jihei, eastern China and Far East areas, Russia were in continental arc setting.

The geodynamic setting across the Paleozoic to Mesozoic transition in Patagonia and the Antarctic Peninsula (SW Pangea) has been strongly debated. Hypotheses of terrane accretion, episodes of shallower to flattened subduction, long-lived stages of crustal extension, or even subduction arrest have been variably proposed. We have compiled and re-evaluated the available whole-rock geochemistry and zircon Hf-isotope data for Permian to Triassic rocks from Patagonia and the Antarctic Peninsula, and compared these findings with the orogenic events in these regions. We have identified that two orogenic cycles occurred along the SW margin of Pangea during the Permian-Triassic interval, namely the Gondwanide and Chonide/Peninsula orogenies. Both orogenies coexisted with the development of magmatic arcs; the Permian arc exhibits an overall I-type signature that switched to A-type towards ca. 252 Ma, whereas the Triassic arc has an S-type signature in the Antarctic Peninsula and intraplate features in Patagonia. The Hf isotope data for zircon exhibit broadly subchondritic values, suggesting significant crustal contribution in the magmatic source during both cycles. The short- and long-term temporal behavior of the isotopic trends suggests variations that may be attributable to the participation of primitive and/or evolved sources. We conclude that the geochemical and isotopic signatures of the magmas, together with different styles of crustal deformation, resulted from the interaction of the upper and lower plates, consistent with the evolution of an accretionary-type margin along SW Pangea during Permian and Triassic times. • We review the Permian-Triassic magmatic arc evolution in Patagonia and the Antarctic Peninsula using geochemical and Hf isotopic data. • Permian magmatic rocks show an I-type signature, while Triassic magmatism varies between Patagonia and the Antarctic Peninsula. • Subchondritic Hf-isotope values indicate shifts in tectonic regimes. • Magmatism developed on continental crust during the Gondwanide and Chonide/Peninsula orogenies, respectively. • Our findings support subduction-related magmatism, typical of an accretionary-type margin evolution. [ABSTRACT FROM AUTHOR]

The Triassic paleogeographic configuration before the Central Atlantic Ocean's opening and the Pangea's breakup establishes that Iberia was close to North America and North Africa. We present U Pb and Hf isotope data of Triassic siliciclastic rocks of the Western Algarve basin (Southwest Iberia, Portugal) to draw inferences on their provenance to define the crustal evolution of the potential sources. Detrital zircon age populations of five samples of Triassic sandstones (68–80 % Neoproterozoic; 5–23 % Paleoproterozoic; 5–14 % Mesoproterozoic; <5 % Archaen and < 4 % Paleozoic) differ significantly from those of the underlying Carboniferous turbidites of the South Portuguese Zone suggesting provenance from outside present-day SW Iberia. Hf isotope signatures of the zircon grains from the western Algarve Triassic sandstones unravel a complex crustal evolution characterized by successive cycles of input of juvenile magmas and magmas derived from the reworking of older crust. Archean detrital zircon grains with positive εHf(t) values and model ages of 3.1–3 Ga indicate juvenile crust formation (Leonian event), while a grain dated at ca. 2.6 Ga showing negative εHf(t) values and model ages of 3.1 Ga suggests that the Archean crust became reworked later (Liberian event). Zircon grains dated between 2.4 and 2.5 Ga having positive to slightly negative εHf(t) values and model ages of 3.3–2.6 Ga model ages correspond to magmatism older than the Eburnean event known in the Reguibat shield, involving a juvenile component mixed with variable proportions of reworked Archean crust. Younger Paleoproterozoic grains (ca. 2.10 to 2.05 Ga; Eburnean-Birimian event) having positive εHf(t) values and model ages of 2.3–2.1 Ga and negative εHf(t) values and model ages of 3.6–2.6 Ga, also indicate interaction of juvenile sources with mixing of old crust. Mesoproterozoic grains show positive εHf(t) values and model ages of 2.3–2.1 Ga, suggesting juvenile crust formation and reworking of the Eburnean crust. Neoproterozoic (ca. 695–555 Ma) detrital zircon with positive εHf(t) values and model ages of 0.76–0.58 Ga point to juvenile crust formation (i.e. Cadomian/Pan-African and Avalonian arcs). They also have negative εHf(t) values in the range − 21.6 to −11.7 and model ages of 3.2–2.1 Ga, suggesting reworking of older crust. In summary, the εHf(t) values and U Pb age pattern of the zircon grains from the Triassic siliciclastic rocks are similar to NW Africa and North America potential sources. Still, there is a notable gap in juvenile crust production during the Siderian in the peri-Eastern Laurentia, Avalonia, and Ganderia potential sources unknown in NW Africa. The lack of ca. 525–380 Ma and ca. 380–330 Ma detrital zircon in the western Algarve Triassic sandstones makes it challenging to admit an Atlantic margin of North America and SW Iberia provenance. [Display omitted] • Iberia was close to North America and North Africa before Triassic Pangea's breakup. • Zircon ages of Triassic Algarve sandstone suggest provenance from outside SW Iberia. • Zircon U-Pb-Hf data reveal complex crustal evolution of Triassic sandstone sources. [ABSTRACT FROM AUTHOR]

The analysis of εHf(t) time series data from zircon reveals notable discrepancies based on sample type (igneous versus detrital), statistical weighting methodology, and geographic sampling bias. These differences warrant caution when interpreting data in the context of tectonic settings and the history of supercontinents. In terms of tectonic setting, accretionary orogens dominate in both sedimentary basins that host detrital zircons and in igneous zircon sources. Because of differences between the various time series, emphasis in this study is on peaks, valleys and secular trends and not on absolute εHf(t) values. Specifically, the igneous time series for εHf(t) in zircons shows more peaks and valleys than corresponding detrital time series for both weighted and unweighted data (weighting corrects for disproportionate geographic sampling). Also, sample-based (each sample considered separately) and site-based (samples grouped by geographic location and age) results align closely to the igneous time series, whereas the site-based detrital series displays more negative εHf(t) values. Regardless of the type of time series, the failure to compensate for disproportionate geographic sampling increases the prospects of producing an unrepresentative time-series. Nine zircon age peaks (both detrital and igneous) have corresponding εHf(t) peaks (3200, 2700, 2500, 2150, 1500, 1100, 750 Ma) and two have corresponding age valleys (1800–2000, 550 Ma). With exception of a geographically widespread 1500 Ma peak, most of the εHf(t) peaks and valleys are controlled by specific geographic regions and are likely not be global in extent. Two distinct periods (200–0 and 1800–1600 Ma) display εHf(t) signatures that rise steadily for 100–200 Myr, coinciding with the final stages of supercontinent assembly and the transition to the retreat of exterior orogens. An εHf(t) peak at 750 Ma and a high at 1400–1100 Ma partly overlap with supercontinent breakup and valleys at 550 Ma and 900 Ma with supercontinent assembly. A large εHf(t) valley at 2000–1800 Ma corresponds with the onset of craton collisions that led to the final assembly of Columbia at 1800–1600 Ma. The steep rise in εHf(t) in the last 200 Myr in both igneous and detrital zircons is controlled by sites in Circum-Pacific orogens in North and South America and Southwest Asia, and it parallels the breakup of Pangea. The general increase in zircon εHf(t) in the last 500 Myr in both detrital and igneous data reflects an increase in the proportion of isotopically juvenile components in accretionary orogens. [Display omitted] • Geographic sampling biases produce non-representative εHf(t) time series. • Nine global zircon age peaks have corresponding εHf(t) peaks. • Rises in εHf(t) at 300–200 and 1800–1600 Ma correspond to supercontinent assemblies. • Zircon sources of all ages are chiefly accretionary orogens. [ABSTRACT FROM AUTHOR]

Junggar Basin is an important exploration zone for sandstone‐hosted uranium deposits in north‐west China. However, neither the provenance of the host sandstone nor the uranium supply capacity of the potential source rocks have been well evaluated. To determine the provenances of the Mesozoic to Cenozoic sandstone grains and to evaluate relationships between the uranium source and the detritus provenances, a field investigation was performed at the Honggou section in the southern Junggar Basin. U–Pb geochronology and Hf isotopes were obtained from populations of detrital zircons from Jurassic through Palaeogene sandstones. The detrital zircon U–Pb ages display three main groups: 145–190 Ma, 250–360 Ma, and 360–460 Ma. The detrital zircon age distributions and the Hf isotopic characteristics of the sandstones correspond to different igneous rock units within the North and Central Tianshan Mountains. Therefore, the changes in the relative proportions of the zircon age populations indicate that there were major shifts of the provenance areas for the sandstones throughout the Early Jurassic to Palaeogene interval. The majority (92%) of Hf isotope εHf(t) values are positive and in the range of +0.7 to +15.5, which indicates that the majority of the zircons had crystallized in igneous rocks that were mainly derived from juvenile crust or depleted mantle. The majority (93%) of the two‐stage model ages (TDM2) are less than 1.8 Ga, thereby indicating the source of the majority of the igneous rocks was from the melting of ancient Meso‐Proterozoic juvenile crust. Carboniferous–Permian intermediate‐felsic igneous rocks in the Tianshan Mountains may be the primary source of released mobilized uranium and uranium‐enriched siliciclastics into the southern Junggar Basin. This study will assist in future uranium prospecting in this region. [ABSTRACT FROM AUTHOR]

The relationship between plutonic and volcanic components of magmatic plumbing systems continues to be a question of intense debate. The Oki-Dōzen Islands, Sea of Japan, preserve outcrops of temporally associated plutonic, hypabyssal, and volcanic rocks. Post-intrusion uplift juxtaposed Miocene syenites in inferred faulted contact with volcanic trachytes that are cut by rhyolite hypabyssal dikes. This provides a window deep into the timing and origins of magma storage architecture and dynamics. Zircon is ubiquitous in all samples; our aim is to determine what its age and composition can reveal about the plutonic-volcanic connection. Here we show magma source characteristics are recorded in zircon Hf isotopes; source composition and assimilation of heterogeneous hydrothermally altered crust in zircon O isotopes; and extensive fractional crystallization in zircon trace elements. Combined with new U-Th-Pb SHRIMP zircon ages, 6.4–5.7 Ma, compositional data show pluton formation was by protracted amalgamation of discrete magma pulses. The rhyolite dike preserves an evolved fraction segregated from these discrete magmas. Synchronous with plutonism was a volcanic eruption of trachyte magma derived from the same source, which may have stalled at a relatively shallow depth prior to eruption. Stalling occurred at least above the amphibole stability zone because amphibole-compatible Sc and Ti were not depleted in the trachyte melt resulting in elevated values of these in volcanic compared to plutonic zircon. Identifying smaller episodic magma pulses in a larger magmatic complex places constraints on potential magma fluxes and eruptible volumes. High-flux, large volume, plume-related ocean island magmatic systems may have extensive vertically distributed multi-stage magmatic reservoirs and subduction-related systems transcrustal magma reservoirs. By contrast, Oki-Dōzen was a low-flux system with incremental pluton growth and small- to moderate-scale eruptions. [ABSTRACT FROM AUTHOR]

We utilized the Neoma™, a recently released MC-ICP-MS platform offered by ThermoFisher Scientific, to assess the behavior of the Lu-Yb-Hf system during laser ablation analyses of various zircon standards as well as solution-based analyses of the JMC-475 Hf standard doped with varying quantities of Yb and Lu. The primary goal of this work was to characterize the behavior of the Yb interference correction on the Neoma™ platform since this is one of the biggest issues in the Hf isotope analysis community and because the Neoma™ platform will supplant the Neptune™ series instrument. During laser ablation analysis, we found that the overall data quality scales proportionally with the total Hf signal intensity, with higher signal analyses producing extremely accurate (within 1 εHf unit) and precise (sub εHf unit within-run standard errors) data. At low Yb signals (<0.1 V 173Yb), we were not able to produce an accurate internal Yb mass bias factor. However, utilizing an empirical approach allows for the application of session-specific relationships between the Yb and Hf mass bias factors, determined by analysis of standards of varying Yb content, to produce accurate εHf values from zircons with higher Yb/Hf ratios even where the total Hf signal intensity is relatively low. Similar behavior was observed in the solution analyses. Lastly, while the behavior of the Yb interference correction on the Neoma™ platform appears comparable to the Neptune™ series MC-ICP-MS, further work will help refine the understanding of the controls on mass bias behavior, oxide formation, session-to-session stability, etc. [ABSTRACT FROM AUTHOR]

The Jinba deposit is an orogenic gold deposit located in the Markakuli shear zone, in the southern part of the Altay orogenic belt, northwestern China. Several granite and diorite dykes are present in the area of the mine, with ore bodies occurring in the diorite dykes. However, the diagenetic age, genesis, and evolution of these magmas, and the tectonic setting of the dyke emplacement process, remain unclear. The present study is based on a detailed geological survey, zircon U–Pb dating, Lu–Hf isotopes, and geochemical analysis of the granitic and diorite dykes. The crystallization ages of the granitic and diorite dykes are 384.5 ± 1.2 Ma and 393.9 ± 3.5 Ma, respectively, which indicates formation in the Early to Middle Devonian. Zircon εHf(t) values of the granitic and diorite dykes are 1.43 to 5.2 and −4.47 to −1.18, respectively, with a corresponding two-stage model of depleted mantle (TDM2) ages of 1046 to 1285 Ma and 1242 to 2623 Ma, respectively. This indicates that the granitic and diorite dykes were formed by the mixing of mantle magma and crustal materials to varying degrees, and diorite dykes are more obviously contaminated by the lower crust. Geochemical analysis shows that the granite dykes have a high SiO2 (72.51%–74.87%) and moderate Al2O3 (12.88%–14.04%) content, a total alkali of (K2O + Na2O = 5.51%–6.44%), and aluminous (A/CNK = 1.0–1.02). Granite dykes are enriched in LREE and Th, U, and Pb, and depleted in P, Sr, and Nb elements, with clear Eu negative anomalies (δEu = 0.62~0.66). The SiO2 content of diorite dykes is 51.48%–53.71%, Al2O3 contents are high (14.70%–15.99%), K2O is 1.94%–2.54%, Na2O is 2.97%–3.96%, MgO contents are high (5.15%–6.46%), and TFe2O3 is (13.42%–15.13%), enriched Sr, U, Pb, deficient Th elements, rare earth fractionation is not obvious, and Eu anomaly is not obvious (δEu = 0.93~1.1). We conclude that the Early to Middle Devonian magmatism in the southern margin of Altay (which corresponds to the Jinba gold deposit) may have formed in an island arc-related subduction environment. [ABSTRACT FROM AUTHOR]

[Display omitted] • We report the first reliable age data for Karoo rift magmatism in Mozambique. • Our U/Pb ages prove Karoo rift magmatism started during ca. 185 – 190 Ma. • Eruption of 182–178 Ma rift magmas released abundant volatiles into atmosphere. New U-Pb ages for zircons constrain the duration of silicic magmatism and timing of coeval mafic magmatism across the main rift zone of the Karoo large igneous province in Mozambique. Our 190 ± 2 Ma, 188.4 ± 0.9 Ma, 181.7 ± 1.0 Ma, 180 ± 3 Ma, 178 ± 2 Ma and 172 ± 2 Ma ages support periodicity of Karoo magmatism previously inferred from 40Ar/39Ar age data. The ∼ 190–188 Ma ages confirm early onset of magmatism and the ∼ 182–178 Ma ages correlate the bimodal volcanic successions of the Lower Zambezi and the Movene Formation with widespread silicic magmatism across the rift zone. The ∼ 172 Ma age corresponds to waning magmatic activity. The age range and Hf isotopic compositions of zircons indicate up to ∼9 Ma lifespan for the Jurassic silicic magma chambers and suggest that the ∼2700–400 Ma xenocrysts represent crustal sources of the host rocks. The available chronological data indicate that the ∼183 Ma main phase magmatism was largely confined within the main Karoo and Kalahari basins and that the preceding and subsequent phases were mainly associated with the Karoo rift zone. Judging from geochemical literature, different kinds of magmas were erupted during the successive magmatic phases. We calculate from published geochemical data that the mafic main phase magmas were relatively poor in CO 2 and SO 2 and the lava stacking patterns point to low eruption rates, which suggests that degassing of sedimentary wall-rocks of intrusions probably triggered the coeval Pliensbachian-Toarcian extinction. In contrast, the mafic late phase magmas were rich in CO 2 and SO 2 and at least some of the lavas indicate high eruption rates. We propose that efficient degassing from widespread mafic magmatism and explosive eruption of over 30,000 km3 of silicic magmas in the Karoo rift zone linked the ∼182–178 Ma late phase magmatism with contemporaneous global biosphere crises. [ABSTRACT FROM AUTHOR]

Carbonate rocks, as one of the magmatic rocks with little but significant geological significance in nature, are generally considered to be mantle-derived causes, and shell-derived causes are rarely reported. The exposed dioprosene carbonate in the Annamba area of the southeast edge of the Tarim Basin is irregular and vein-like intrusive into the surrounding rock, and the surrounding rock trapper body can be seen inside the rock, and has a dense block structure and fine grain structure, indicating that it is an igneous carbonate rather than a sedimentary carbonate rock. The geochemical characteristics of rocks show that the carbonate-rich CaO (content (mass fraction, the same below) is 24.63%-33.20%), SiO (33.11%-40.07%), poor MgO (2.25%-3.21%), FeO (1.38%-2.03%), the total rare earth element content ((45.44-91.47) ×10) and the total light rare earth element content ((42.83-86.06)×10) are significantly lower, and the relative enrichment Rb is significantly lower Large ionic lithophilic elements such as Ba, Th, Sr, etc., with losses of Nb, Ta, Zr, Hf and other high field strength elements, are obviously different from mantle-derived carbonate rocks, and similar to shell-derived carbonate rocks. Zircon in the dioprose carbonate develops oscillating ring band structure, with obvious Ce positive anomaly, weak Eu negative anomaly and low Th/U value (average value 0.24), indicating that it is metamorphic deep molten zircon. The study of the U-Pb-Lu-Hf isotope of zircon zircon showed that the age of the zircon Hf isotope pattern had an age peak of about 2.59 Ga, and the age of lithogenesis was (1 910±13) Ma, which was consistent with the formation era of the Milan rock group and the era of hemp grain phase metamorphism, respectively. Combined with the comprehensive analysis of the previous research results, it is believed that the dipyrene carbonate in the Annamba area may be the product of the deep melting action of the Diopline Dali rock of the Milan rock group under the condition of hemp granular phase metamorphism, which is the response of the Columbia supercontinent aggregation event in the southeast edge of the Tarim Basin [ABSTRACT FROM AUTHOR]

Zircon xenocrysts from two diamond-barren kimberlite pipes (Leningrad and Ruslovaya) in the West Ukukit kimberlite field opened a 'window' to the buried crustal basement in the northern Siberian craton. Zircon U-Pb ages reveal a close affinity of the basement of the Khapchan belt to the Archaean Anabar province and a significant tectonomagmatic reworking in the Paleoproterozoic (~2.1–1.8 Ga) due to collision between the Anabar province and the Olenek province. The West Ukukit kimberlite field experienced multiple tectonomagmatic reactivation from ~670 to 144 Ma, which can be attributed to interaction of the deep crust with mantle-derived melts. Hf isotope composition of zircon xenocrysts reveals significant addition of juvenile material into the crust during the Paleoproterozoic orogeny in diamond-barren kimberlite fields, which is different from the reworking crust in the southern Yakutia diamondiferous kimberlite fields. Eruption of the Leningrad and Ruslovaya pipes were constrained as the Late Jurassic, much later than the well-known Late Silurian-Earth Devonian kimberlites in the West Ukukit kimberlite field. A NE-trending, >2000 km long kimberlite corridor is proposed to account for a prolonged lithospheric channel for episodic eruption of kimberlites in the Siberian craton. The diamond storage in the lithosphere beneath the West Ukukit kimberlite field may have been largely reduced by the Paleoproterozoic orogeny and Phanerozoic reworking. [ABSTRACT FROM AUTHOR]

Extensive magmatism in NE China, eastern Central Asian Orogenic Belt, has produced multi-stage granitic plutons and accompanying W mineralization. The Narenwula complex in the southwestern Great Xing'an Range provides important insights into the petrogenesis, geodynamic processes and relationship with W mineralization. The complex comprises granodiorites, monzogranites and granite porphyry. Mafic microgranular enclaves are common in the granodiorites, and have similar zircon U–Pb ages as their host rocks (258.5–253.9 Ma), whereas the W-bearing granitoids yield emplacement ages of 149.8–148.1 Ma. Permian granodiorites are I-type granites that are enriched in large-ion lithophile elements and light rare earth elements, and depleted in high field strength elements and heavy rare earth elements. Both the mafic microgranular enclaves and granodiorites have nearly identical zircon Hf isotopic compositions. The results suggest that the mafic microgranular enclaves and granodiorites formed by the mixing of mafic and felsic magmas. W-bearing granitoids are highly fractionated A-type granites, enriched in Rb, Th, U and Pb, and depleted in Ba, Sr, P, Ti and Eu. They have higher W concentrations and Rb/Sr ratios, and lower Nb/Ta, Zr/Hf and K/Rb ratios than the W-barren granodiorites. These data and negative ϵHf(t) values (–6.0 to –2.1) suggest that they were derived from the partial melting of ancient lower crust and subsequently underwent extreme fractional crystallization. Based on the regional geology, we propose that the granodiorites were generated in a volcanic arc setting related to the subduction of the Palaeo-Asian Ocean, whereas the W-bearing granitoids and associated deposits formed in a post-orogenic extensional setting controlled by the Mongol–Okhotsk Ocean and Palaeo-Pacific Ocean tectonic regimes. [ABSTRACT FROM AUTHOR]