The Eoarchean Isua supracrustal belt (ISB) in West Greenland comprises one of the oldest rock records, yet its geological evolution and geodynamic setting are still debated. Major order questions involve the timing and number of the tectono-metamorphic events leading to the formation of mineral assemblages and structures observed today. Interpreted cross-cutting relationships and crystallization ages of the Ameralik (mafic) dykes have been used to suggest an Eoarchean metamorphic age for the most pervasive event (e.g., Nutman et al., 2004, JGS 161, 421-430). Recent studies, in contrast, argue that this event is Neoarchean in age, as constrained via garnet (-plagioclase-hornblende) dating (e.g., Eskesen et al. 2023, Geology 51, 1017-1021; Ramírez-Salazar et al., unpublished data). In this study, we present data of eight garnet grains from two metapelitic samples from the eastern limb of the ISB to acquire further information about the metamorphic evolution. Both samples share a similar mineral assemblage, featuring a matrix predominantly composed of porphyroblastic garnet with ±chlorite, biotite, white mica, quartz, and ±plagioclase. The garnets exhibit a diversity of unevenly distributed inclusions dominated by quartz, plagioclase, white mica, chlorite, and ilmenite. Additionally, apatite, ±monazite, ±allanite, ±rutile, and ±zircon, as well as some iron-arsenide and -sulphide minerals, are abundant as inclusions. Textural evidence in combination with major and trace element zoning reveals three distinct garnet core to rim domains referred to as garnet I to garnet III. The porphyroblasts’ inclusion-rich cores (garnet I) are characterized by a bell-shaped spessartine component and heavy rare earth element zoning pattern, along with a relatively flat grossular and pyrope pattern. The garnet annuli (garnet II) are grossular-rich, with a constant or slightly increasing pyrope and spessartine components already at their minimum. Garnet II typically exhibits less inclusions. A drop in grossular together with an increase in pyrope components, and the virtual absence of inclusions mark the third garnet domain (garnet III). Our examination of the chemical, mineralogical, and textural characteristics across the different garnet domains reveals the growth of garnet through distinct mineral reactions under variable metamorphic conditions. These domains may be linked to either distinct metamorphic growth stages within a single event or disparate metamorphic events in the tectono-thermal history of the ISB. To unravel the chronological sequence of garnet growth, we present texturally resolved dating of individual garnet domains using the Sm-Nd isochron method.

Banded Iron Formations (BIFs) are authigenic, marine sediments directly reflecting the chemical composition of ancient seawater. BIFs serve as prime geochemical archives for the reconstruction of Precambrian marine environments. However, due to the scarcity of well preserved Archean rocks, atmospheric and hydrospheric environmental conditions within this time frame are still incompletely understood. In particular, elemental fluxes derived from continental weathering and submarine hydrothermal fluxes that affected ancient seawater chemistry are cornerstones for our understanding of the evolution of marine habitats through time. Here we present major- and trace element concentrations in combination with Nd isotopic compositions of 13 samples of Mesoarchean Algoma-type greenschist-facies BIFs from the ca 3.0 Ga old Murchison Greenstone Belt, South Africa. Individual Fe- and Si-rich layers are monitored for sample purity based on their chemical composition. Neodymium isotope compositions, in combination with trace element contents of BIF samples with varying amounts of clastic detritus, are further used to reconstruct the Murchison depositional environment and identify the origin of dissolved and detrital components entering the ancient ocean around 3.0 Ga ago. Eight samples with low immobile element concentrations display typical shale-normalized Archean seawater-like rare earth and yttrium (REYSN) patterns with positive LaSN, EuCN, and GdSN anomalies, super-chondritic Y/Ho ratios, and an enrichment of heavy REYSN over light REYSN, implying an open marine-dominated depositional setting with contributions from submarine high-temperature, hydrothermal systems. A Sm-Nd regression line yields an age of 2.98 ± 0.19 Ga that overlaps with the proposed depositional age, suggesting negligible post-depositional alteration on the REY composition of the pure BIF layers. In contrast, higher concentrations of immobile elements (e.g., Zr) and/or non-seawater-like REYSN patterns are characteristic for the remaining five BIF samples, indicating elevated detrital input or post-depositional alteration. A regression line of the impure BIF layers yields an age of 2.49 ± 0.15 Ga, reflecting a potential post-depositional overprinting event such as the 2.6 Ga old Limpopo orogeny. The Nd isotopic compositions of pure and impure BIF samples cover a wide range of ca. two epsilon units suggesting a mixture of weathered mafic and felsic sources for the dissolved and suspended fluxes into the Murchison ocean.

Banded iron formations (BIFs) are marine chemical sedimentary rocks that serve as prime archives for Precambrian paleo-environmental reconstructions. However, due to the scarcity of well-preserved Archean rocks, the aquatic environments of early Earth remain poorly constrained. In particular, fluxes derived from continents and submarine hydrothermal systems that affected Archean seawater chemistry are crucial for the understanding of the evolution of marine environments. To fill this gap, we present major- and trace element data in combination with Sm-Nd isotopes of individual BIF layers from the ca. 3.0 Ga old Murchison Greenstone Belt (MGB) of South Africa. BIF layers with low immobile element concentrations show seawater-like shale-normalized (subscript SN) rare earth and yttrium (REYSN) patterns with heavy over light REYSN enrichment and positive LaSN, EuSN, GdSN, and YSN anomalies, implying an anoxic marine depositional setting with contributions from high-temperature, hydrothermal systems. These BIF samples yield a Sm-Nd age of 2993 +/- 97 Ma that overlaps with the proposed depositional age suggesting negligible post-depositional alteration. In contrast, BIF layers with non-seawater-like REYSN patterns yield a Sm-Nd age of 2504 +/- 161 Ma, which can be linked to post-depositional alteration during the ca. 2.7 Ga Limpopo orogeny. The range of initial epsilon Nd values from-1.74 to + 0.15 in pristine BIF samples suggests that elements of mixed juvenile and evolved material from emerged continents and/or hydrothermal systems affected Murchison seawater and indicates potential oceanic water mixing in the Murchison region with water masses derived from the northern Pietersburg and the southern Kaapvaal regions.

The isotopic composition of lavas associated with mantle plumes has previously been interpreted in the light of core–mantle interaction, suggesting that mantle plumes may transport core material to Earth’s surface 1–5 . However, a definitive fingerprint of Earth’s core in the mantle remains unconfirmed. Precious metals, such as ruthenium (Ru), are highly concentrated in the metallic core but extremely depleted in the silicate mantle. Recently discovered mass-independent Ru isotope variations ( ε 100 Ru) in ancient rocks show that the Ru isotope composition of accreted material changed during later stages of Earth’s growth 6 , indicating that the core and mantle must have different Ru isotope compositions. This illustrates the potential of Ru isotopes as a new tracer for core–mantle interaction. Here we report Ru isotope anomalies for ocean island basalts. Basalts from Hawaii have higher ε 100 Ru than the ambient mantle. Combined with unradiogenic tungsten (W) isotope ratios, this is diagnostic of a core contribution to their mantle sources. The combined Ru and W isotope systematics of Hawaiian basalts are best explained by simple core entrainment but addition of core-derived oxide minerals at the core–mantle boundary is a possibility.

The concentration of dissolved oxygen in the deep oceans has varied over Earth History, but the timing of the transition from anoxic to oxic deep oceans is debated. Under modern-day, oxic, deep ocean conditions, alteration of the upper sections of mafic oceanic crust with U-rich seawater leads to U enrichment, low Th/U ratios, and heterogeneous U-238/U-235 ratios relative to fresh mid-ocean ridge basalt (MORB). Given the solubility behaviour of U, its uptake into altered oceanic crust (AOC) is expected to be smaller and less isotopically fractionated when deep oceans were anoxic and thus U-poor. Determining when, in the geological record, the U elemental and isotopic systematics of ancient oceanic crust first resemble modern day AOC should indicate when deep oceans became oxic. We provide U concentration, Th/U, and U isotopic data on upper-crustal sections of three ophiolites from 750 to 480 Ma, spanning the period inferred for deep ocean oxygenation (similar to 850 to 400 Ma). The ophiolites at 480 and 540 Ma have high U contents, low Th/U ratios, and variability in U-238/U-235 ratios like modern-day AOC, reflecting seawater alteration of oceanic crust under oxygenated seawater conditions. In contrast, the 750 Ma ophiolite does not show the distinctive decreasing Th/U with increasing U concentrations trend of modern AOC and has fewer samples with U-238/U-235 ratios perturbed from mantle values, reflecting alteration under largely anoxic deep ocean conditions. This is also supported by Fe3+/Fe-T ratios in these samples that are like unaltered modern MORB. Thus, our data suggest oxygenated deep oceans at some time between 750 and 540 Ma, either reflecting a full transition or intermittent deep ocean oxygenation events within an otherwise anoxic deep ocean.

Upper Neoproterozoic greywackes of the Cadomian basement and the subsequent overlap sequence of largely upper Cambrian to Lower Ordovician siliciclastic sedimentary rocks are the oldest deposits of Saxo-Thuringia. This study aims to establish a stratigraphic affiliation and discrimination criteria between the individual units based on comprehensive whole-rock geochemical, Rb–Sr and Sm–Nd isotopic analyses. The most notable differences can be observed in the markedly elevated SiO₂ content and concurrently reduced Al₂O₃ content of the upper Cambrian to Lower Ordovician units, in addition to the depletion of Na and Ca resulting from the prior weathering-related decomposition of feldspars. Upper Cambrian to Lower Ordovician units have considerably higher 87Rb/86Sr ratios (ca. > 4) than the Neoproterozoic ones. Considering these characteristics, the depositional age of the low-grade metamorphosed Clanzschwitz Group and Seidewitz Formation must be shifted from the Late Neoproterozoic to the late Cambrian or Early Ordovician. A differentiation criterion could also be established for the first time between the two macroscopically indistinguishable Ediacaran and Carboniferous greywacke units of the Lausitz Block, with the latter unit having significantly higher concentrations of the trace elements Ni, V, Cr and Co. Comprehensive Sm–Nd isotope investigations validate a uniform West African provenance for the Saxo-Thuringian units, with model ages around 2 Ga. However, locally in East Thuringia and in the Carboniferous greywackes of the Lausitz Block, younger model ages (1.7–1.3 Ga) indicate a different provenance or an admixture of juvenile volcanic material. Trace and rare earth element (REE) analyses using in situ LA–ICP–MS on chert samples from the Rothstein Formation and chert clasts from the Lausitz Group deposits revealed markedly divergent REE signatures and provide compelling evidence that the Lausitz Group is not composed of redeposited erosion products from the older backarc basin (Rothstein Formation). Therefore, the commonly accepted two-stage (backarc–retroarc) basin model for Saxo-Thuringia during the Neoproterozoic requires revision.

Tungsten isotope anomalies in modern rocks are exclusively associated with plume-related basalts and may provide a unique tool to identify recycled plume material in subduction zone magmatism. In Central America, the Cocos and Coiba Ridges are subducting with the Cocos plate. These ridges may introduce material into the arc magma source that was derived from the Galapagos plume, which has been shown to carry anomalous W-182 signatures. Here, we report negative mu W-182 values together with trace element data for <5 Ma old adakites and back-arc basanites, as well as accreted basalt terranes that formed as a result of Galapagos plume activity in the last 70 Myr. In adakites and basanites, these mu W-182 deficits derive from a slab melt component that dominates the W budget of their source. In addition, negative mu W-182 in accreted mafic terranes attest to the longevity of the primordial W isotope signature in the Galapagos plume and the involvement of a Galapagos-related magma source in the Central American arc system over time.

Geochemical and isotopic data are presented for 32 Ma-old high-K andesites and dacites from the Alpine Chain. The samples consist of plagioclase, amphibole, titanomagnetite and rare biotite and quartz. Geochemical and isotope data indicate that slab-derived fluids, sediment melts and presumably AFC processes involving continental crust played a key role in the petrogenesis of the high-K rocks. A contribution of fluids is suggested based on the overall enrichment of large-ion lithophile elements and related high Ba/La, Ba/Zr, Ba/Th, Ba/Nb and Pb/Nd, sometimes distinctively higher than average continental crust. Positively correlated Ba/Nb–Th/Nb relationships, low Ce/Pb, low Nb/U and a negative correlation of Pb isotopes with Ce/Pb and Nb/U and positive ∆ 7/4 and ∆ 8/4 values similar to GLOSS imply the additional involvement of a sediment-derived melt. Negatively correlated Nb/Ta–Zr/Hf ratios at overall low Nb/Ta (13–7.5) are best explained by parental magma differentiation involving amphibole and biotite in a continental arc system. The samples have moderately unradiogenic Nd (εNd: – 2.0 to – 6.7) and radiogenic 87Sr/86Sr isotope compositions (0.7085–0.7113), moderately radiogenic Pb isotope compositions (206Pb/204Pb: 18.50–18.72; 207Pb/204Pb: 15.59–15.65; 208Pb/204Pb: 38.30–38.67), and elevated δ18O values (+ 6.5 to + 9.1 ‰). Epsilon Hf isotope values range from + 2.5 to – 4.0. Negative εHf(t) and εNd(t) values and 206Pb/204Pb ratios are correlated with elevated K2O abundances that indicate enrichment in K2O is related to AFC processes. The offset of εHf at a given εNd points to involvement of aged garnet-bearing crustal lithologies. The latter feature is qualitatively consistent with modification of unexposed primary basaltic andesites by AFC processes involving deep crustal material. In conclusion, in an Alpine context, inferred unexposed primitive high-K basaltic to andesitic melts are generated in the mantle wedge through fluid infiltration from the descending slab where fluids may have caused also partial melting of sedimentary rocks that mixed with evolving andesite–dacite compositions towards shallow-level intrusive and extrusive rocks. High-K and related trace element and isotope features thus result from a combination of already elevated values with participation of fluids and melts and probably AFC processes.

The Ediacaran Campo Alegre-Corup ' a Basin in South Brazil developed in two stages, the synorogenic passive rift (Basin Stage -605-590 Ma) and the post-collisional caldera volcano (Caldera Stage -583-577 Ma), respectively. Volcanic rocks from the Basin Stage show a bimodal compositional spectrum with dominant basalt and subordinate silicic rocks. The basaltic rocks are transitional to mildly alkaline, exhibiting Ocean Island Basalt-like (OIB-like) trace element enrichment patterns, with depletion in Nb and Ta, however, and crustal-like Sr-Nd isotopic signatures, suggesting that they were derived from low degrees (-5%) of partial melting of an enriched lithospheric mantle source. The silicic rocks are transitional to mildly alkaline trachydacites associated with subordinate rhyolites, exhibiting trace element compositions typical of A2-type granitoids, produced by fractional crystallization of the coeval basalts in the Moho. Volcanic rocks from the Caldera Stage are constituted mainly by alkaline trachytes and rhyolites, occurring primarily as pyroclastic sequences coupled to minor effusive lava flows and domes, also exhibiting trace element compositions typical of A2-type granitoids. They are associated with subordinated effusive transitional to mildly alkaline basalts with Island Arc Basalt-like (IAB-like) trace element signatures. Compared to the Basin Stage, the basalts from the Caldera Stage result from higher degrees (-15 %) of partial melting of possibly the same enriched lithospheric-mantle sources during the lithospheric root collapse of a cratonic terrane. The silicic rocks from the Caldera Stage are also derived from the coeval basalts by fractional crystallization in the Moho. However, an additional stage of differentiation in the upper crust is required to explain their silica-enriched compositions and eruptive styles. Results from this study support a connection between the silicic volcanic rocks from the Caldera Stage and the plutonic bodies from the nearby A-type Graciosa Province. Lu-Hf isotopes from detrital zircon suggest an Andean arc-type tectonic setting during the Paleoproterozoic (-2,185 Ma) history of the Luis Alves Terrane (LAT) basement. This tectonic setting was responsible for the arc-like signatures of the intraplate lithospheric-derived rocks of both bimodal volcanic sequences. Crustal-like Sr-Nd-Hf isotopic characteristics result from a protracted isotope evolution of their enriched mantle sources, and each tectono-magmatic stage results from a different extensional setting, which has implications for the metacratonization of the LAT.

AbstractDue to the inherently fluid‐mobile nature of W, the 182W record of the early Earth may have been obscured by fluid‐induced mobilization of W. To investigate W mobilization in Archean greenstone sequences, we analyzed 182W isotope systematics and major and trace element concentrations in samples from the 3.53 Ga old Onverwacht Group of the Kaapvaal Craton (South Africa) and the >3.51 Ga old Badampahar Group of the Singhbhum Craton (India). Our results for mafic and ultramafic metavolcanic rocks show W/Th ratios significantly higher than primary magmatic values, which suggests fluid‐induced W enrichment. Samples least affected by secondary W enrichment (W/Th < 0.26) show no resolvable W isotope anomalies from modern mantle values in both cratons. Samples from the Kaapvaal Craton with elevated W/Th exhibit deficits in 182W as low as −8.1 ± 4.3 ppm compared to the modern mantle. Covariations of μ182W with W/Th, and Ce/Pb suggest that negative isotope signatures were introduced during secondary fluid‐mediated processes. The enrichment of W is most evident in altered ultramafic rocks comprising serpentine, resulting in additional covariations between MgO, LOI, and W/Th. The W isotope composition of serpentinized komatiites reflects the composition of younger intruding granitoids. We therefore infer the latter as a possible source of W‐rich fluids. The Badampahar Group samples exhibit little W isotope variability. A well‐resolved 182W deficit of −6.2 ± 2.9 ppm was determined in a single komatiite sample, which indicates an unknown fluid source, currently not represented in any other unit of the Singhbhum Craton.

Primitive (high-Cr, Ni), high-Mg andesites (HMA) at convergent plate margins are considered primary, mantlederived melts, and are not part of the classical tholeiitic or so-called calc-alkaline igneous differentiation series. Their genesis is often considered the product of melting of lower crustal sequences or the subducting slab, though their genesis is far from being understood. Alternatively, they may represent differentiated rocks from boninitic precursors. Here we present isotope and geochemical data for a rare suite of high-Mg andesites that were preserved as decimetre-sized boulders in molasse-type sedimentary rocks of the Oligocene-Miocene Gonfolite Lombarda (Como Formation; Italy), as part of the post-orogenic alpine sedimentary succession. The HMA have moderate to high MgO (1.9-6.4 wt%), high Al2O3 (16.3-18.8 wt%), along with high Cr (30-306 ppm) and Ni (13-92 ppm), and moderate Yb (1.2-2.5 ppm) and Y (12-26 ppm) abundances, matching those of primitive HMA. These HMA are LILE- and LREE-enriched and most samples have negligible negative Eu anomalies. Primitive mantle-normalized compositions show depletions in Nb, Ta, P, Ti and Y. Most samples have unradiogenic Nd (epsilon Nd: -6.2 to -7.8) and radiogenic 87Sr/86Sr isotope compositions (0.708 to 0.710), elevated 818O values (+7.6 %o to +9.5 %o) and radiogenic Pb isotope compositions, with a pronounced variation in 207Pb/204Pb and 208Pb/204Pb at rather constant 206Pb/204Pb. Initial epsilon Hf isotope values range from -0.4 to -2.3, some of which deviate from the Hf-Nd crust-mantle isotope array. One sample is unevolved (87Sr/86Sr: 0.708; epsilon Nd: -3.3, epsilon Hf: +1.8, 818O: 8.5 %o) whereas another sample is strongly evolved (87Sr/86Sr: 0.720; epsilon Nd: -9.3, epsilon Hf: -5.8, 818O: 9.3 %o); the latter probably representing a crustal melt. The remaining samples have intermediate compositions (87Sr/86Sr: 0.709-0.713; epsilon Nd: -6.2 to -8.5, epsilon Hf: -0.4 to -4.3, 818O: 7.6-10.6 %o) that either result from limited AFC processes or represent source heterogeneities. The sum of these features cannot be the result of a simple slab or mantle wedge melting process. To account for the observed geochemical signatures of the highMg andesites, a three-stage model is suggested that invokes melting of slab-derived sediment diapirs, followed by melt-rock-reaction in the mantle wedge and subsequent crustal assimilation-fractional crystallization (AFC). The diapirs that rise into the mantle wedge are composed of subducted wet, Alpine sediments. Hydrous dacitic (siliceous) partial melts derived from them react with the ambient mantle wedge and cause the formation of boninitic melts with elevated MgO, Ni and Cr; the archetype features of primitive high-Mg andesites. Subsequent interaction with the overlying arc crust is evidenced by crustal xenoliths, which may account for some isotope features of the rock suite. We consider this scenario most plausible because it is relatively simple, and explain most if not all geochemical features, based on modelling and experimental evidence.

The recycling of mafic oceanic crust in subduction zones represents an important geological process to explain the geochemical diversity of the Earth's mantle. Based on radiogenic isotope and trace element data it has been proposed that recycled crust may form part of the deep-rooted mantle sources of ocean island basalts. Here we provide Mo isotope data for basalts from the ocean islands of La Palma and Hawaii to further address this issue. Samples have Mo isotope ratios (δ98/95Mo from −0.51 to −0.26 ± 0.06‰; 2σ; for La Palma and −0.50 to −0.11 ± 0.06‰; 2σ; for Hawaii) that extend to values significantly lower, and Ce/Mo ratios (112 to 32 for La Palma and 86 to 9 for Hawaii) that are significantly higher than those for the depleted mantle and bulk silicate Earth. Experimental data and model calculations show that neither magmatic processes (partial melting, residual sulphide) nor assimilation of marine sediments readily explain these observations as both processes result in δ98/95Mo values that are either too high, or Ce/Mo that are too low compared to the measured data for basalts from La Palma and Hawaii. Rather, their Mo isotope and Ce/Mo characteristics are uniformly matched by eclogite-facies, MORB-type meta-basalts that once formed part of oceanic lithosphere subducted to mantle depths. Our observations therefore provide strong evidence that subduction-modified, mafic oceanic crust is present in the mantle source of La Palma and Hawaii. As such, combined Mo isotopes and Ce/Mo ratios in ocean island basalts may provide an additional distinctive and robust tracer of recycled lithosphere in the mantle.

An interlaboratory comparison (ILC) was organised to characterise 87Sr/86Sr isotope ratios in geological and industrial reference materials by applying the so‐called conventional method for determining 87Sr/86Sr isotope ratios. Four cements (VDZ 100a, VDZ 200a, VDZ 300a, IAG OPC‐1), one limestone (IAG CGL ML‐3) and one slate (IAG OU‐6) reference materials were selected, covering a wide range of naturally occurring Sr isotopic signatures. Thirteen laboratories received aliquots of these six reference materials together with a detailed technical protocol. The consensus values for the six reference materials and their associated measurement uncertainties were obtained by applying a Gaussian, linear mixed effects model fitted to all the measurement results. By combining the consensus values and their uncertainties with an uncertainty contribution for potential heterogeneity, reference values ranging from 0.708134 mol mol‐1 to 0.729778 mol mol‐1 were obtained with relative expanded uncertainties of ≤ 0.007 %. This study represents an ILC on conventional 87Sr/86Sr isotope ratios, within which metrological principles were considered and the compatibility of measurement results obtained by MC‐ICP‐MS and by MC‐TIMS is demonstrated. The materials characterised in this study can be used as reference materials for validation and quality control purposes and to estimate measurement uncertainties in conventional 87Sr/86Sr isotope ratio measurement.

Abstract Mass‐dependent Mo isotope variations are a promising new tracer to study magmatic processes in different geological settings. We report the first Mo isotope data for the Kamchatka arc system in the Northwest Pacific, comprising basaltic lavas of a complete Southeast‐Northwest traverse from the volcanic arc front through to the back arc region. The majority of volcanic centers investigated directly override the Hawaii‐Emperor Seamount Chain, which is currently being subducted underneath the arc system. Our Mo isotope data show systematic trends with Ce/Pb, Ce/Mo, Nb/Zr, La/Sm, and 143Nd/144Nd ratios from the volcanic arc front to the back arc. Arc front lavas have higher δ98/95Mo and lower Ce/Pb, Ce/Mo, Nb/Zr, La/Sm compared to back arc lavas. Because the involvement of subducted sediments can be excluded, we attribute the observed variations to a change in the mantle source composition from the arc front to the back arc regions. The isotopic and chemical budget of arc front lavas is dominated by a slab fluid component (high δ98/95Mo, low Ce/Pb, Ce/Mo), whereas mantle‐like Ce/Pb, Ce/Mo, elevated Nb/Zr and La/Sm in the back arc samples suggest an enriched mantle source. Combined δ98/95Mo, Nd, and Pb isotope data in back arc lavas are very similar to those observed for modern ocean island basalts from Hawaii. We thus explore the possibility that the back arc mantle was contaminated by a Hawaii‐type, enriched asthenospheric mantle component from the subducted Hawaii‐Emperor Seamount Chain.

The Digermulen Peninsula in northeastern Finnmark, Arctic Norway, comprises one of the most complete Ediacaran-Cambrian transitions worldwide with a nearly continuous record of micro-and macrofossils from the interval of the diversification of complex life. Here, we report on the provenance and post-depositional alteration of argillaceous mudstones from the Digermulen Peninsula using rare earth elements and Sm-Nd and Rb-Sr isotopic systematics to provide an environmental context and better understand this important transition in Earth's history. The studied sections comprise a mid-Ediacaran glacial-interglacial cycle, including the Nyborg Formation (ca. 590 Ma) and Mortensnes Formation (related to the ca. 580 Ma-old Gaskiers glaciation), and the St & PRIME;ahpogieddi Formation (ca. 560-537 Ma), which yields Ediacara-type fossils in the Indreelva Member and contains the Ediacaran-Cambrian boundary interval in the Manndrapselva Member and basal part of the informal Lower Breidvika member (ca. 537-530 Ma). Three sample groups, (1) Nyborg and Mortensnes for-mations, (2) the lowermost five samples from the Indreelva Member and (3) the remaining samples from the Indreelva as well as from the Manndrapselva and Lower Breidvika members, can be distinguished, belonging to distinct depositional units. All samples have negative epsilon(Nd)(T) values (-6.00 to -21.04) indicating a dominant input of terrigenous detritus with an old continental crust affinity. Significant shifts in Sm-Nd isotope values are related to changes in the sediment source, i.e. Svecofennian province vs Karelian province vs Svecofennian province plus in addition likely some juvenile (late Neoproterozoic volcanic) material, and probably reflect palaeotectonic reorganisation along the Iapetus-facing margin of Baltica. The combined Rb-Sr isotopic data of all samples yield an errorchron age of about 430 Ma reflecting the resetting of the Rb-Sr whole-rock isotope systems of the mudstones during the Scandian tectono-metamorphic event in the Gaissa Nappe Complex of Finnmark. Preservation of palaeopascichnids coincides with the sedimentation regimes of sample groups 2 and 3 while other Ediacara-type fossils, e.g. Aspidella-type and frondose forms, are limited to the sample group 3. Our results are similar to those of earlier studies from the East European Platform in suggesting oxic seafloor conditions during the late Ediacaran.