Coupled trace element and Hf-isotope measurements of Hadean through Paleoarchean zircons from the Singhbhum Craton indicate derivation from a long-lived, mantle-derived protocrust

Baddeleyite is an important U‐Pb geochronometer and Hf isotope tracer that commonly occurs as an accessory phase in silica‐undersaturated igneous rocks of terrestrial and extra‐terrestrial origin. Currently, very few well‐characterised, large sized reference materials are available for baddeleyite U‐Pb geochronology and Hf isotope measurement. In this study, we document a baddeleyite reference material (SK10‐3) of Cenozoic age. SK10‐3 is inclusion‐free and does not contain secondary alteration minerals. The baddeleyite has uniform U‐Pb ages and Hf isotope ratios, within analytical uncertainty, as demonstrated by multiple LA‐ICP‐MS spot analyses (weighted mean 206Pb/238U age: 31.59 ± 0.11 Ma, MSWD = 0.7, n = 197) and LA‐MC‐ICP‐MS analyses (arithmetic mean 176Hf/177Hf ratio: 0.282741 ± 59, 2s, n = 188). Seven ID‐TIMS analyses yielded a weighted mean 206Pb/238U age of 31.592 ± 0.020/0.022/0.040 Ma (n = 7, 2s, MSWD = 2.2). Nine aliquots of MC‐ICP‐MS analyses yielded an arithmetic mean 176Hf/177Hf ratio of 0.282742 ± 8 (2s). We further demonstrate that the method of shallow‐pit (~ 2 μm depth) ablation substantially improves the precision and accuracy of baddeleyite U‐Pb ages. SK10‐3 has a relatively high 176Yb/177Hf ratio (~ 0.007) compared with most other baddeleyites, allowing the precise measurement of βYb and may be useful in generating the βYb‐βHf relationship during LA‐MC‐ICP‐MS Hf isotope measurement. SK10‐3 may be a useful addition to previously distributed baddeleyite reference materials for microbeam‐based U‐Pb geochronology and Hf isotope measurements.

Accurate and precise Nd and Hf isotope measurements of samples with low contents by simple adjustments of an Apex Omega membrane de-solvating system.

Large‐scale magmatic activity and associated mineralization in South China are linked to the subduction of the palaeo‐Pacific Plate, although specific processes have remained controversial including the timing of subduction initiation and lithospheric extension. We present new geochemical data and zircon U–Pb and Lu–Hf isotope measurements on volcanic rocks, granites and mafic dikes from coastal south‐eastern China along the Eurasian continental margin. The biotite monzogranites show I–type granitoid affinity and fractional crystallization with zircon εHf(t) values ranging from −10.15 to +0.50, suggesting magma derivation from the melting of lower crust with the addition of juvenile crustal or mantle components. The biotite granites are typical of highly fractionated A‐type granites with εHf(t) values ranging from −3.63 to +1.35, indicating magma hybridization between anatectic granitic and mantle‐derived mafic magmas. The diabase dikes have zircon εHf(t) values ranging from −2.99 to +1.71, with high La/Nb and La/Ta ratios. This suggests derivation from partial melting of a lithospheric mantle metasomatized by fluid from a subducting–slab, with contributions of depleted asthenospheric mantle components. Our data, combined with those from previous studies, suggest that the shallow subduction of the palaeo–Pacific Plate beneath the Eurasian continent had begun by ca. ~170 Ma at least and the subduction orientation changed to oblique with respect to the continental margin. Steepening of the subduction angle likely caused a slab rollback during the Early Cretaceous, resulting in a tectonic transition from compression to extension in South China at ca. 145 Ma.

New zircon reference materials for in situ zircon radiogenic Hf isotope and stable Zr isotopic determinations made by laser ablation multi‐collector inductively coupled plasma‐mass spectrometry (LA‐MC‐ICP‐MS) are required due to high data productivity and consequently high reference material consumption rate. This study examines a new natural zircon for Zr isotope ratios by double spike thermal ionisation mass spectrometry (TIMS), and for Hf isotopes by bulk solution nebuliser (SN)‐MC‐ICP‐MS with both Zr and Hf determined by LA‐MC‐ICP‐MS. A total of five zirconium isotope measurements from drilled zircons, determined by TIMS, yield a mean δ94/90ZrIPGP‐Zr value of ‐0.09 ± 0.06‰ (2s). Five and eight hafnium isotope measurements for powders from the drilled zircons and Ban‐1‐4 by SN‐MC‐ICP‐MS, yield mean 176Hf/177Hf ratios of 0.282985 ± 0.000011 (2s) and 0.282982 ± 0.000007 (2s), respectively. The mean δ94/90ZrIPGP‐Zr value and 176Hf/177Hf ratio determined by LA‐MC‐ICP‐MS analyses are ‐0.06 ± 0.09‰ (2s, n = 504) and 0.282985 ± 0.000035 (2s, n = 327), respectively. The isotopic homogeneities suggest that the Ban‐1 zircon is a suitable reference material for microbeam Zr and Hf isotopic measurements.

The Karavansalija Mineralized Center (KMC) with its Au–Cu skarn mineralization associated with the Rogozna Mountains magmatic suite in southwestern Serbia belongs to the Oligocene Serbo-Macedonian magmatic and metallogenic belt (SMM-MB). Samples from intrusive and volcanic rocks at the KMC show typical arc signatures of subduction-derived magmas through enrichment in large-ion lithophile elements (LILE) and depletion of high–field strength elements (HFSE). The magmas developed a high-K (calc-alkaline) fractionation trend and evolved toward shoshonitic compositions. Whole-rock trace element data suggest plagioclase-absent, high-pressure amphibole ± garnet fractionation that generates adakite-like hydrous magmas during evolution in lower crustal magma chambers. Zircon LA–ICP–MS and high-precision CA–ID–TIMS dating together with zircon trace elements and Hf isotope measurements were carried out in order to couple the geochronologic and geochemical evolution of the KMC. The results suggest that magmatism starts around 29.34 Ma with granitic to rhyodacitic subvolcanic intrusions followed by a more evolved magmatic intrusion that was emplaced into Cretaceous limestone, generating a widespread skarn alteration at ca. 28.96 Ma. After a period of quiescence of about 1.2 My, either another magma body evolved or the same upper crustal magma chamber was recharged and also likely partly reactivated older plutonic rocks as indicated by xenocrysts. The REE ratios shift from apatite, titanite ± amphibole-dominated fractionation of the older magmatic event to crystallization of allanite, efficiently depleting the LREE and Th/U in the younger upper crustal magma. After a lamproite-like melt was injected, the increased heat and fluid pressure led to the expulsion of a quartz-monzonite porphyritic stock at ca. 27.72 Ma, strongly interacting with the skarns and established a fertile hydrothermal system. Soon after a non-mineralized second pulse of some porphyry dykes cut the previous phenocryst-rich “crowded” porphyries and skarns at ca. 27.60 Ma, thus bracketing the maximum timespan of ore mineralization to about 112 ± 45 Ka. Increased contribution of a lamproite-like melt is inferred from the presence of phlogopite micro-phenocrysts, phlogopitization of biotite, and diopside clusters in the latest porphyry dykes. There is a trend of increased crustal assimilation from the oldest volcanic phase to the emplacement of the youngest porphyry dykes recorded by ɛ-Hf of the zircons. Oligocene occurrences of significant base metal mineralization within Serbia, northern Macedonia, and Greece, e.g., Crnac, Rudnik, Veliki Majdan, Stratoniu, or the Cu–Au porphyry at Buchim (northern Macedonia), are all associated with trachy-andesitic (quartz latitic) porphyry dykes, which originated through post-collisional tectonic settings or upper plate extension involving reworking of crustal arc-derived rocks and partial melting of the mantle wedge. This study demonstrates that on the basis of field relationships and the application of high-precision CA-ID-TIMS zircon age data, pulses of porphyry dykes of a 10ka age range can be distinguished, and the timing of mineralization can be parenthized.

Lu-Hf isotopic systematics is a powerful tool and gained importance as a geochemical tracer in geosciences. A multi-collector inductively coupled plasma mass spectrometer coupled with a laser ablation system has been used to perform zircon hafnium (Hf) isotopic analysis, and protocol is established for measurement of Hf isotopes. Toward this, two zircon standards, Z91500 and Plesovice, have been used for Hf isotopic measurements at four different spot sizes (50, 40, 25, and 20 μm). The isotopic data for ≥25 μm have an excellent agreement with published data, but for 20 μm, the results are erroneous and irrelevant to geological application. It has been observed that Hf beam intensity has a linear relation to the volume of the target (RM) ablated. 178 Hf/177 Hf ratio and ɛHf for both standards are comparable with the published recommended values. The present study indicates that 176 Lu/177 Hf ratio for Z91500 is more homogeneous than Plesovice zircon. The 176 Hf/177 Hf isotopic ratio for 50 and 25 μm shows an excellent agreement with the previously reported data. However, for 40-μm spot size, a slightly higher but negative offset of -123 and -105 ppm in 176 Hf/177 Hf ratio have been observed for Plesovice and 91500, respectively.

We present multitechnique U‐Pb geochronology and Hf isotopic data from zircon separated from rapakivi biotite granite within the Eocene Golden Horn batholith in Washington, USA. A weighted mean of twenty‐five Th‐corrected 206Pb/238U zircon dates produced at two independent laboratories using chemical abrasion‐isotope dilution‐thermal ionisation mass spectrometry (CA‐ID‐TIMS) is 48.106 ± 0.023 Ma (2s analytical including tracer uncertainties, MSWD = 1.53) and is our recommended date for GHR1 zircon. Microbeam 206Pb/238U dates from laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS) and secondary ion mass spectrometry (SIMS) laboratories are reproducible and in agreement with the CA‐ID‐TIMS date to within < 1.5%. Solution multi‐collector ICP‐MS (MC‐ICP‐MS) measurements of Hf isotopes from chemically purified aliquots of GHR1 yield a mean 176Hf/177Hf of 0.283050 ± 17 (2s, n = 10), corresponding to a εHf0 of +9.3. Hafnium isotopic measurements from two LA‐ICP‐MS laboratories are in agreement with the solution MC‐ICP‐MS value. The reproducibility of 206Pb/238U and 176Hf/177Hf ratios from GHR1 zircon across a variety of measurement techniques demonstrates their homogeneity in most grains. Additionally, the effectively limitless reserves of GHR1 material from an accessible exposure suggest that GHR1 can provide a useful reference material for U‐Pb geochronology of Cenozoic zircon and Hf isotopic measurements of zircon with radiogenic 176Hf/177Hf.

Abstract Precise in situ zircon U‐Pb dating and Lu–Hf isotopic measurement using an LA‐ICP‐MS system, whole‐rock major and trace element geochemistry and Sr–Nd isotope geochemistry were conducted on the volcanic host rocks of the Tongyu copper deposit on the basis of further understanding of its geological characteristics. Three zircon samples from the volcanic host rocks yielded 206Pb/238U weighted average ages ranging from 436±4 Ma to 440±5 Ma, which are statistically indistinguishable and coeval with the ca. 440 Ma northward subduction event of the Paleo‐Qinling oceanic slab. The volcanic host rocks were products of magmatic differentiation that evolved from basalt to andesite to dacite to rhyolite, forming an integrated tholeiitic island arc volcanic rock suite. The primitive mantle‐normalized trace element patterns for most samples show characteristics of island arc volcanic rocks, such as relative enrichment of LILE (e.g. Th, U, Pb and La) and depletion of HFSE (e.g. Nb, Ta, Ti, Zr and Hi). Discrimination diagrams of Ta/Yb vs Th/Yb, Ta vs Th, Yb vs Th/Ta, Ta/Hf vs Th/Hf, Hf/3 vs Th vs Nb/16, La vs La/Nb and Nb vs Nb/Th all suggest that both the volcanic host rocks from the Tongyu copper deposit and the volcanic rocks from the regional Xieyuguan Group were formed in an island arc environment related to subduction of an oceanic slab. Values of ISr (0.703457 to 0.708218) and ∊Nd(t) (–2 to 5.8) indicate that the source materials of volcanic rocks from the Tongyu copper deposit and the Xieyuguan Group originated from the metasomatised mantle wedge with possible crustal material assimilation. Most of the volcanic rock samples show good agreement with the values of typical island arc volcanic rocks in the ISr–∊Nd(t) diagram. The involvement of crustal‐derived material in the magma of the volcanic rocks from the Tongyu copper deposit was also reflected in the zircon ∊Hf(t) values, which range from –3.08 to 10.7, and the existence of inherited ancient xenocrystic zircon cores (2616±39 Ma and 1297±22 Ma). The mineralization of the Tongyu copper deposit shows syn‐volcanic characteristics such as layered orebodies interbedded with the volcanic rock strata, thus, the zircon U–Pb age of the volcanic host rocks can approximately represent the mineralization age of the Tongyu copper deposit. Both the Meigou pluton and the volcanic host rocks were formed during the ca. 440 Ma northward subduction of the Paleo‐Qinling Ocean when high oxygen fugacity aqueous hydrothermal fluid released by dehydration of the slab and the overlying sediments fluxed into the mantle wedge, triggered partial melting of the mantle wedge, and activated and extracted Cu and other ore‐forming elements. The magma and ore‐bearing fluid upwelled and erupted, and consequently formed the island arc volcanic rock suite and the Tongyu VHMS‐type copper deposit.

From the 3000 km2 Eoarchean Itsaq Gneiss Complex (IGC) of Greenland, zircon U-Pb dating of numerous meta-granitoid and orthogneiss samples is integrated with geologic observations, whole rock geochemistry and a strategic subset of zircon Hf and whole rock Nd isotopic measurements. This shows that there are multiple episodes of TTG suite formation from ∼3890 to 3660 Ma, characterized by zircon initial εHf≈0 and whole rock initial εNd of > +2. These rocks mostly have geochemical signatures of partial melting of eclogitized mafic sources, with a subset of high magnesian, low silica rocks indicating fusion by fluid fluxing of upper mantle sources. The TTG suites are accompanied by slightly older gabbros, basalts and andesites, which have geochemical signatures pointing to magmas originating from fluid fluxing of upper mantle sources. The data show the formation of juvenile crust domains in several discrete events from ∼3900 to 3660 Ma, probably at convergent plate boundaries in an environment analogous, but not identical to, modern island arcs. In the Isua area, a northern ∼3700 Ma terrane formed distal from a predominantly ∼3800 Ma terrane. These terranes were juxtaposed between 3680 and 3660 Ma—respectively the age of the youngest rocks unique to the northern terrane and the lithologically distinctive ultramafic-granitic Inaluk dykes common to both terranes. This shows the assembly of different domains of juvenile rocks to form a more expansive domain of “continental” crust. A rare occurrence of high-pressure granulite is dated at ∼3660 Ma, demonstrating that assembly involved tectonic crustal thickening. This continental crust was then reworked in the 3660 to 3600 Ma Isukasian orogeny . In the northern part of the Isua area, 3660 to 3600 Ma granites were emplaced into ∼3700 Ma tonalites. The earliest granites are nebulous, and sigmoidal schlieric inclusions within them demonstrate ductile extension. Younger granite sheets were emplaced into extensional ductile-brittle fractures. These granite-tonalite relationships are overprinted by widespread development of late Eoarchean (pre-3500 Ma Ameralik dyke) brittle-ductile extensional cataclastic textures, together demonstrating that extension was polybaric. The southern part of the Isua area largely escaped 3660 to 3600 Ma high temperature processes and has sparse granite sheets commonly focused into coeval shear zones. In the rest of the complex, deeper crustal levels during the Isukasian orogeny are widely preserved. These experienced upper amphibolite to granulite facies moderate- to low-pressure syn-kinematic metamorphism, forming complex migmatites rich in granitic-trondhjemitic neosome. The migmatites were intruded by composite ferrogabbro and granite bodies, in which syn-magmatic extensional features are locally preserved. Thus 3660 to 3600 Ma crustal recycling involved elevated crustal thermal gradients in an extensional regime. Crustal melts formed in the Isukasian orogeny have zircon initial εHf<0 and whole rock initial εNd of ≤0, showing incorporation of slightly older Eoarchean juvenile crust. A Phanerozoic example of collisional orogeny followed by crustal thinning is explored as an analog for the Isukasian orogeny.

Guidelines for reporting zircon Hf isotopic data by LA-MC-ICPMS and potential pitfalls in the interpretation of these data

The Quanji (全吉) Massif is located in the Northwest China, which is interpreted as a micro-continent that is composed of metamorphic basement and stable cover strata. There are some controversies of genetic relationship between the Quanji Massif and the major cratons in China. In this study, we obtained in situ zircon U-Pb and Hf isotopic compositions of the Yingfeng (鹰峰) rapakivi granites from the northwest Quanji Massif by application of LA-MC-ICP-MS technique. Twenty U-Pb age measurements points are concordant or near concordant, and their weighted mean 207Pb/206Pb age is 1 793.9±6.4 Ma (MSWD= 1.09), yields an upper intercept age of 1 800±17 Ma (MSWD=0.41); 19 Hf isotope measurements yield a two-stage Hf model ages (T DM2) of 2.63 to 2.81 Ga, with a weighted average age of about 2.70±0.02 Ga and ɛHf(t) values variate between -8.91 to -5.35. This indicates that magma source of the Yingfeng rapakivi granites were produced from partial melting of late stage of Neoarchean juvenile crust, and suggests a significant crustal growth event occurred in the Quanji Massif at that time. The Quanji Massif might be an ancient continental segment detached from the Tarim Craton based on the crustal growth history and other geological records. The Tarim Craton (including the Quanji Massif) and the North China Craton had a similar or homological early crustal evolution around ∼2.7 Ga, which implies that Tarim Craton might be one of the component parts of North China Craton.

Spatial and temporal evolution of Liassic to Paleocene arc activity in southern Peru unraveled by zircon U–Pb and Hf in-situ data on plutonic rocks

Synthetic zircon doped with hafnium and rare earth elements: A reference material for in situ hafnium isotope analysis

Provenance of Meso- to Neoproterozoic cover sediments at the Ming Tombs, Beijing, North China Craton: An integrated study of U–Pb dating and Hf isotopic measurement of detrital zircons and whole-rock geochemistry

Geochemical studies of geological samples require the precise determination of their major and trace element contents and, when measured, of their isotopic compositions. It is now commonly accepted that the accuracy and precision of geochemical analyses are best estimated by the concomitant analysis of international reference materials run as unknown samples. Although the composition of a wide selection of basalts is relatively well constrained, this is far from being the case for sedimentary materials. We present here a comprehensive set of major and trace element data as well as Nd, Hf, Sr and Pb isotopic compositions for thirteen commonly used international reference materials – eight magmatic rocks (BHVO‐2, BR, BE‐N, BR 24, AGV‐1, BIR‐1, UB‐N, RGM‐1) and five sediments (JLk‐1, JSd‐1, JSd‐2, JSd‐3, LKSD‐1). We determined the concentrations of over forty elements in the magmatic rocks together with Sr, Nd, Hf and Pb isotopic compositions. Our trace element results were both accurate (difference ≤ 3%) and precise (reproducibility at 1s ≤ 3%) and the isotopic results were very similar to other published values. In contrast, we observed a significant chemical and isotopic variability in the sedimentary materials, which we attribute to mineral heterogeneities in the powders. Despite the limitation imposed by this heterogeneity, our work presents a complete set of data determined with a precision not yet achieved in the literature for sedimentary material. We also provide the first Nd, Hf and Pb isotopic measurements for the five sediments, which are commonly used by the geochemical community. Our study of both basalt and sediment reference materials represents a comprehensive and self‐consistent set of geochemical data and can therefore be considered as a reference database for the community.

In situ U–Pb, Sr, Nd and Hf isotopic analysis of eudialyte by LA-(MC)-ICP-MS

The hafnium–neodymium isotopic composition of Atlantic seawater

Combined U–Pb and Lu–Hf isotope measurements of single detrital zircon grains in Carboniferous metasediments from Patagonia delineate the source areas of the sediments. The detritus, represented by four metasandstone samples, was deposited prior to onset of subduction in Late Carboniferous time along the south Patagonian proto-Pacific Gondwana margin. A broad series of detrital zircon age peaks (0.35–0.7 Ga, 0.9–1.5 Ga) and a large spread (0.3–3.5 Ga) in the age spectra require numerous sources. A fifth metasediment was deposited after the onset of subduction. This syncollisional sample shows two distinct U–Pb age peaks at c . 290 Ma and 305 Ma. This points to a few sources only (Patagonia, West Antarctica). Initial Hf-isotope compositions of selected U–Pb dated zircons from the Carboniferous metasediments reveal zircon protoliths originating from both recycled crust and juvenile sources (εHf (T=0.4–3.5Ga) =−14 to +12). A comparison with crustal compositions of possible source areas indicates that the detritus mainly originated from the interior of Gondwana (Extra-Andean Patagonia, the Argentine Sierra de la Ventana, southernmost Africa, East Antarctica), as well as northern Chile and northwestern Argentina. The sediment transportation paths are consistent with an autochthonous palaeogeographical position of Patagonia with respect to Gondwana in Carboniferous time.

Hf isotopic compositions of the standard zircons and baddeleyites used in U–Pb geochronology