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In the Variscan Bohemian Massif, (ultra-)potassic plutons are conspicuously associated with the high-grade, lower crustal/upper mantle Gfohl Unit (Moldanubian Zone). They can be subdivided into two contrasting groups: (1) coarse amphibole–biotite melagranite to quartz syenite with conspicuous K-feldspar phenocrysts (the ‘durbachite suite’), and (2) essentially equigranular biotite–two-pyroxene quartz syenites to melagranites (the ‘syenitoid suite’). The latter suite, represented by the Tabor and Jihlava plutons, is characterized by an originally ‘drier’ mineral assemblage orthopyroxene + clinopyroxene + Mg-biotite + plagioclase + K-feldspar + quartz, with accessory zircon, apatite, ilmenite, monazite and/or rutile + chromite. The rich assemblage of both rock-forming and accessory minerals allows testing of numerous geothermobarometers. The resulting P–T data are mutually consistent; they document emplacement of the parental magmas at mid-crustal levels (~5 kbar/19 km for Tabor and 7–8 kbar/26–30 km for Jihlava) and record near-isobaric crystallization from at least 1170 °C to the solidus. New Isotope-Dilution Thermal Ionization Mass-Spectrometry (ID-TIMS) U–Pb ages for zircon (336.9 + 0.6 Ma) and rutile (336.8 + 0.8 Ma) from the Tabor Pluton, together with previously published ages from the Jihlava Pluton, provide temporal constraints for the emplacement and rapid cooling of the syenitoids below c. 600 °C. This supports the hypothesis of post-tectonic emplacement of a hot and dry melt (>1200 °C?) into an essentially consolidated orogenic crust. The two syenitoid plutons have comparable, crust-like radiogenic isotope signatures (87Sr/86Sr337 = 0.7114–0.7133, e337Nd = −6.8 to −8.0). This, in context of whole-rock geochemical variation and K-feldspar Pb isotopic compositions, is consistent with generation from a strongly enriched lithospheric mantle source. Shortly before melting, the local orogenic mantle was most likely modified by deep subduction and relamination of felsic crustal material of the Saxothuringian provenance, transformed to the felsic high-pressure granulites common in the Moldanubian Zone. In the subsequent evolution of the two-pyroxene syenitoid plutons, crystal fractionation and accumulation played a key role, unlike in the durbachite suite itself, where magma mixing with leucogranitic melts was much more important. Structural relations inside and around the (ultra-)potassic plutons (~343–335 Ma) suggest that – besides different depths and specific processes of magma emplacement – these plutons track different kinematic histories and evolutions of regional strain fields in their high-grade country rocks in this crucial period of the Variscan Orogeny.

Garnet and zircon geochronology combined with trace element partitioning and petrological studies provide tight constraints on evolution of the UHT-(U)HP terrain of the Orlica-Śnieznik Dome (OSD) in the NE Bohemian massif. Lu-Hf dating of peritectic garnet from two mesocratic granulites constrained the time of its initial growth at 346.9 ± 1.2 and 348.3 ± 2.0 Ma recording peak 2.5 GPa pressure and 950 °C temperature. In situ, U-Pb SHRIMP dating of zircon from the same granulite gave a younger age of 341.9 ± 3.4 Ma. Ti-in-zircon thermometry indicates crystallization at 810–860 °C pointing to zircon formation on the retrograde path. Lu partitioning between garnet rim and zircon suggest equilibrium growth and thus U-Pb zircon age constrain the terminal phase of garnet crystallization which lasted about 6 Ma. All Sm-Nd garnet ages obtained for mesocratic and mafic granulites are identical and consistently younger than the corresponding Lu-Hf dates. They are interpreted as reflecting cooling of granulites through the Sm-Nd closure temperature at about 337 Ma. The estimated PTt path documents the ca. 10 Ma evolution cycle of the OSD characterized by two distinct periods: (1) 347 - > 342 Ma period corresponds to nearly isothermal decompression resulting from crustal scale folding and vertical extrusion of granulites, and (2) at > 342–337 Ma which corresponds to a fast, nearly isobaric cooling.

A new data set of ca. 500 LA–ICP-MS U–Pb detrital zircon ages for six metasedimentary units from the Tuscan basement (Apuan Alps, Monti Pisani, Monticiano-Roccastrada), along with a precise SHRIMP U–Pb crystallization age of a metavolcanic unit (Apuan Alps) have been collected to determine their depositional ages and provenance. These results have been integrated with the recently published ca. 900 U–Pb detrital zircon ages from Elba Island to draw a complete picture of the Paleozoic journey of the Tuscan basement. A major change in the sources supplying sediments to the Tuscan basins is shown to occur during this journey. Detrital zircon ages of early Cambrian to middle Ordovician metasediments mirror those of coeval northern Africa sediments: most samples were sourced in western Africa, while one sample is derived material from central northern Africa. The Tuscan block was therefore located at the peri-Gondwana margin, close to central northern Africa. The prominent mid-Ordovician magmatic arc activity (ca. 460 Ma) at the northern Gondwana margin and its detritus, characterise the zircon age distribution of Ordovician and Silurian volcano-sedimentary rocks, that were therefore generated at the northernmost Gondwana margin during subduction and subsequent initial Paleotethys rifting. The Carboniferous–Permian metasediments are dominated by populations of Ordovician and Variscan-age zircons, with a minor occurrence of Neoarchean and Paleoproterozoic zircons that is best explained by recycling of European Neoproterozoic–Cambrian metasediments. In summary, the main sources supplying the Tuscan basins were located in northern Africa throughout Cambrian–Ordovician times, shifting to the volcanic arc active at the northern Gondwana margin during the middle Ordovician. During Variscan and post-Variscan times, detrital zircon sources were mostly located in European terrains, witnessing the shift of Tuscany from Africa to Europe.

Elba Island, located midway between Corsica and mainland Italy, is a small but important fragment of the Adria Plate. It has a rich sedimentary record preserved in a stack of tectonic nappes of both continental margin and oceanic origin. Especially the detrital zircons in early Paleozoic to early Mesozoic metasedimentary rocks provide an archive of many important geological events in the island's history. Elba Island and Adria originated along the northern margin of Gondwana, but drifted north in Silurian times to become part of Europe. A large new dataset of LA-ICP-MS and SIMS U–Pb zircon ages allows us to trace this history. Three main stratigraphic units have been investigated. The oldest Porto Azzurro Unit was deposited in the early Cambrian and has zircon age distributions indicating a typical northern African provenance, most likely sourced from the Saharan Metacraton. The Ortano Unit has a simple, mostly unimodal Ordovician age distribution that is entirely dominated by metavolcanic rocks and their erosional products; a sample of the metavolcanic Ortano Porphyroids provided a SIMS U–Pb zircon age of 460 ± 3 Ma. This phase of intense volcanism is related to the subduction of the Rheic Ocean beneath Gondwana, terminating with initial rifting and subsequent opening of the Paleotethys. This also marks the onset of the separation of a range of European terranes, including Adria and future Elba Island, from Gondwana. The Permo-Triassic Monticiano–Roccastrada Unit is the first to show a European provenance with the appearance of large amounts of Variscan and late to post-Variscan detritus. The presence of Variscan detrital zircons in the Permo-Triassic sediments is unexpected, since a Variscan age signature is so far not well recorded in the Adria Plate. This dataset is the most comprehensive detrital zircon dataset so far available for the Adria Plate and documents Adria's close affinity to Africa in the Lower Paleozoic, as well as its initial rifting within an active continental margin setting during the Ordovician and its final separation and independent evolution since late Palaeozoic times.

Distinctly different crustal blocks converge in southern Tanzania which are thought to belong to the Paleoproterozoic Usagaran/Ubendian Belt, the Mesoproterozoic Irumide Belt and the Neoproterozoic East African Orogen. Zircons from thirteen samples were dated by LA-SC/MC-ICPMS in order to assign the different crystalline basement rocks to one of the above mentioned geological units based on the age of metamorphism and formation of the igneous precursor rocks. The mainly migmatic gneissic samples were taken along a traverse from Mbamba Bay, Lake Malawi to Masasi, S-Tanzania. Zircon cores and rims trace magmatic protoliths between 1000 ± 9 and 1055 ± 6 Ma and metamorphism between 563 ± 10 and 616 ± 12 Ma. Ages belonging to the Usagaran/Ubendian event as well as the 640 Ma EAO event were only found in the westernmost and easternmost part of the transsect, respectively. Magmatic ages of 724 ± 6 and 764 ± 4 Ma were determined in locally confined undeformed granitoid bodies. Mostly similar ages as well as lithological units can be found in the Unango and Marrupa Complexes in N-Mozambique which are considered as part of the Southern Irumide Belt. The exact location of terrane boundary between the Southern Irumide Belt and the Western/Eastern Granulites and the Usagaran/Ubendien Belts in southern Tanzania remains uncertain. With aid of digital elevation data, satellite images and airborne geophysical data we suggest that a combination of fault systems is responsible for the distribution of the different units. The northeastern limit of the Southern Irumide Belt (Unango and Marrupa Complexes) can be traced along a major tectonic boundary, the Mwembesi Fault system, that extends from Malawi to the south of the Mahenge Mountains in Tanzania.

Isotopic dating of detrital zircon populations from metasediments and of magmatic zircon from intercalated metavolcanic layers in the medium- to high-grade part of the Kaoko Belt in Namibia provides first robust constraints on the age of Neoproterozoic sedimentation along the southwestern margin of the Congo Craton. Dating of detrital zircons from metasediments directly overlying the cratonic basement shows maximum sedimentary ages of c. 1.00 and c. 1.45 Ga, and age populations comparable with known protolith ages from the gneisses of the Congo/Kalahari cratons. Dating of zircon from associated metavolcanics constrains the age of the earliest preserved sediments at c. 740–710 Ma. Detrital zircon populations from the samples collected from the upper parts of the metasedimentary succession contain only small proportion of grains with ages similar to those from the Congo Craton. These samples show dominance of c. 1.00 Ga, c. 750 Ma and c. 650 Ma old zircon grains that are probably derived from the Punta del Este – Coastal Terrane (Dom Feliciano and Kaoko belts) that acted as an arc/back-arc domain at c. 650–630 Ma. Neodymium model ages for the samples of metasedimentary cover of the cratonic basement provide another evidence that the youngest preserved sediments could not have been derived from the Congo Craton. Recognition of the Punta del Este – Coastal Terrane crust as a source region for the youngest pre-collisional sediments of the Kaoko Belt suggests that this terrane must have been in close proximity to the Congo Craton passive margin already some time prior to their mutual collision at c. 570–550 Ma. This is in accord with an interpretation that the c. 650–630 Ma arc/back-arc Punta del Este – Coastal Terrane has developed directly on top of, or very close to, the attenuated Congo Craton passive margin.

High-pressure kyanite–K-feldspar granulites in the Běstvina granulite body, which belongs to the Variscan orogenic root in the Bohemian Massif, preserve muscovite, rutile and kyanite inclusions in garnet. High-Ti muscovite (Ti = 0.09–0.20 p.f.u., Si = 0.21–3.24 p.f.u.) included in garnet is associated with quartz and is in crystallographic continuity with biotite, interpreted in terms of exsolution from an original less-dioctahedral higher-Ti muscovite. The assemblage garnet–kyanite–antiperthite–perthite–quartz–rutile and the mineral compositions indicate a peak of metamorphism at about 900 °C and 17–21 kbar, based on P–T pseudosection modeling, ternary-feldspar and Zr-in-rutile thermometry. The matrix assemblage garnet–kyanite–plagioclase-K-feldspar–quartz–rutile–ilmenite and garnet rim compositions at contact with feldspars and quartz indicate the end of overall equilibration in the presence of melt at 12–14 kbar and 820–840 °C. Embayments of biotite and plagioclase locally replacing garnet, and connected with modification of garnet composition, may indicate sites of last isolated melt or diffusion of H2O from that melt down to 10 kbar and 800 °C. Zircon with uniform cathodoluminescence (CL) pattern is present as rims around cores with faint oscillatory zoning, or as entire rounded grains. These zircons gave a cluster of ages at 359 ± 4 Ma, interpreted as the age of metamorphism. Zircon ages from the cores with common faint oscillatory zoning range from 500 to 398 Ma, and are interpreted as magmatic grains variably reset during metamorphism. Two older ages obtained on cores of 620 ± 18 Ma probably represent an inherited zircon component. Molar isopleths of zircon along the P–T path in pseudosections suggest that crystallization of metamorphic zircon occurred during decompression and cooling from 17 to 21 kbar and 900 °C to 12–14 kbar and 820–840 °C. The inferred P–T path and the age of metamorphism are discussed in the framework of a geodynamic model that considers the granulites to be a part of a subducted plate that failed to continue to subduct and was spread below the upper plate.

The Pinjarra Orogen, stretching along the western coast of Western Australia, is one of the least understood orogens on the continent. Exposure is limited to fault-bound basement blocks within the Phanerozoic Perth Basin, which have been interpreted as either remnants of a Mesoproterozoic orogen or as allochthonous blocks within a Neoproterozoic orogen. Thus even the timing of orogenesis is controversial. However, since the orogen is in a critical position for reconstructions of both Rodinia and Gondwana, a better understanding is highly desirable. New U–Pb ages of detrital zircon cores, metamorphic zircon rims and metamorphic monazites from the Northampton Complex, the northernmost and largest of the exposed basement blocks, provide better insights into the sedimentary provenance and metamorphic history of the metasediments exposed in this part of the orogen. Both the monazite ages and the youngest metamorphic zircon rims constrain metamorphism in the Northampton Complex to 1090–1020 Ma. Additionally, a large number of older metamorphic zircon rims pre-date this event and were inherited from the Albany-Fraser Orogen in southwestern Australia, which is also identified as the main source region for the detrital zircon cores. Additional sources of detrital zircons are the Mawson Continent (the South Australian Craton and parts of East Antarctica) and possibly the North Australian Craton, as well as synsedimentary volcanic rocks. However, the combination of ages from the cores and inherited metamorphic rims shows that zircons from the Mawson Continent/North Australian Craton were not directly transported to the Northampton Complex but arrived there after being incorporated into the Albany-Fraser Orogen and then eroded from there. The dataset records therefore two orogenic cycles: (1) erosion of the Mawson Continent/North Australian Craton, deposition along the craton margins, collision between the Mawson Continent and North-West Australian Craton and metamorphism in the Albany-Fraser Orogen and (2) erosion of the Albany-Fraser Orogen, deposition along Australia's western margin and metamorphism during the Pinjarra Orogeny. This highlights the care that must be taken in detrital zircon studies, since many of the detrital cores record a second-order provenance. It also explains how zircons from the Mawson Continent could be transported across the Albany-Fraser Orogen that should normally have been a barrier to northwest-directed sediment transport. Finally, in light of these new and previously published data, we support the interpretation that the Pinjarra Orogen is a Mesoproterozoic orogen formed along Australia's western margin.

Detrital zircon grains in coarse-grained sedimentary rocks of the Noisy formation, (traditionally considered as the H6 unit of the uppermost Hooggenoeg Formation) in the Paleoarchean Barberton Greenstone Belt (BGB) South Africa, are investigated by laser ablation (LA)-ICP-MS to constrain their U–Pb and 207Pb/206Pb ages for depositional age and provenance determination. Drill core and field observations indicate that these rocks are clastic polymictitic diamictites and sandstones. A wide range in 207Pb/206Pb ages between ca. 3600 and 3430 Ma is reported. The youngest detrital zircon grain identified has an age of 3432 ± 10 Ma, constraining the maximum depositional age of the sedimentary sequence and the formation of a major underlying erosional unconformity. The youngest grains correspond in age to the ca. 3460–3430 Ma tonalite–trondjemite–granodiorite (TTG) gneisses of the Stoltzburg terrane and felsic intrusions of the uppermost Hooggenoeg Formation that constitute most of the Songimvelo Block of the BGB on the Kaapvaal craton. The 207Pb/206Pb ages of the oldest grains identified corresponds to plutonic sources identified in older proto-continental blocks of the Kaapvaal craton, namely the ca. 3509 Ma Steynsdorp Block and ca. 3667–3223 Ma Ancient Gneiss Complex (AGC). This new data indicates provenancial linkage between the Songimvelo Block and older proto-continental blocks exposed on the Kaapvaal craton at ca. 3432 Ma. It is argued here, that the Noisy formation is a remnant of the earliest tectonic basin in the BGB, that developed during major tectonic accretion and uplift at ca. 3432 Ma that lead to formation of the erosional unconformity. In conjunction with new drill core and field observations, the geochronological constraints presented here support plate-tectonic processes operating in the proto-Kaapvaal craton that resulted in its formation as a stable continental landmass as early as ca. 3432 Ma.

Detrital zircon U–Pb and Lu–Hf isotope data from Neoproterozoic to Cretaceous sandstones exposed in eastern Greenland, 70°30′–74°N, are reported to characterize and evaluate the provenance from Greenland during pre-breakup and post-breakup sedimentation in the Norwegian–Greenland Sea. Middle Devonian to Lower Cretaceous samples all show similar detrital zircon age distributions characterized by variable Archean populations, abundant Proterozoic populations ranging from ca. 2000 to 900 Ma and a Caledonian population peaking at ca. 440 Ma. Neoproterozoic sediments of the Eleonore Bay Supergroup give a more narrow age distribution with a dominant age peak at 1100 to 1000 Ma, a secondary peak at 1700–1400 Ma, and rare Archean to Paleoproterozoic ages. We suggest that the Neoproterozoic metasediments of the Krummedal and Smallefjord sequences and the Eleonore Bay Supergroup together with Caledonian rocks of age ca. 440 Ma and variable amounts of Paleoproterozoic basement were the main sources for the analyzed Middle Devonian to Lower Cretaceous sandstones. The scarcity of Archean zircons could indicate a rather limited role of the Archean basement rocks of the eastern Greenland Caledonian orogenic belt as a source for some of the analyzed younger sedimentary rocks. The composite age distribution of the zircons from the Phanerozoic eastern Greenland samples, i.e., a minor Archean to Paleoproterozoic (Siderian and Rhyacian) component, abundant Paleoproterozoic (Orosian) to Neoproterozoic (Tonian) ages, and a significant Lower Silurian (Caledonian) signal, is very similar to zircon age distributions reported for Upper Cretaceous turbidite sandstones from large parts of the Norwegian Sea, and to the age distributions determined in this study for three Oligocene sandstone samples from east of Jan Mayen Island. Upper Cretaceous to Paleocene Norwegian Sea sandstones, known to be derived from Norway, differ from this eastern Greenland-derived pattern by a near total lack of Archean zircon ages and a less pronounced Caledonian component. Wide detrital zircon age spectra with a distinct Silurian group and a population of Neoarchean zircons is thus suggested as indicative of sediments sourced from the studied area of eastern Greenland. The Hf isotopic compositions of detrital zircons suggest that Eoarchean crust derived from a source with chondritic Lu/Hf ratios at ca. 3900–3700 Ma contributed to zircon-forming processes in the source area for the eastern Greenland sandstones until ca. 2300 Ma. The Caledonian orogeny in this area was probably a crust reworking event with a limited contribution from depleted mantle.

International audience; LA-ICP-MS U-Pb analyses performed on zircon grains from the Lizio granite yielded an emplacement age of 316 6 Ma. Typical S-C structures show that the Lizio granite was emplaced contemporaneously with dextral shearing along the northern branch of the South Armorican Shear Zone and that it was therefore active at that time. 40Ar/39Ar analyses performed on muscovite grains yielded plateau dates ranging between 311.5 and 308.2 Ma. Muscovite chemistry is typical of primary magmatic muscovite, which precludes a late fluidsinduced resetting of the K-Ar isotopic system. 40Ar/39Ar dates thus likely correspond to the cooling ages below the argon closure temperature. Considering the uncertainties on the measured ages, we can propose that either the Lizio granite cooled down quickly in less than a million of years or that it remained in a hot environment for several millions of years after its emplacement. This latter scenario could have been sustained by shear heating during dextral shearing along the northern branch of the South Armorican Shear Zone.

A detailed description of the newly defined Mendel Formation is presented. This Late Miocene (5.9–5.4 Ma) sedimentary sequence with an overall thickness of more than 80 m comprises cyclic deposition in terrestrial glacigenic, glaciomarine and marine environments. Subglacial till was deposited by a thick grounded Antarctic Peninsula ice stream advancing eastwards through the Prince Gustav Channel, crossing the northernmost part of present-day James Ross Island, with most of the material carried actively at the base of the warm-based glacier. The form of the Prince Gustav Channel originated before the late Miocene and its present glacial over-deepening resulted in multiple grounded glacier advances during the Neogene and Quaternary. The sea prograded from the east and the glacier margin became buoyant, building a small ice shelf, below and in front of which glaciomarine and marine sediments were deposited. These sedimentary deposits are composed of material that was transported mostly by small glaciers and subsequently by the floating ice shelf and by calving icebergs towards the open sea. These environmental and glaciological conditions differ strongly from the present cold-based local glaciers of James Ross Island and the Antarctic Peninsula. These changes were triggered by the global sea level fluctuation connected with climatic changes due to Antarctic ice sheet build up and decay. This reveals Late Miocene obliquity-driven cyclicity with a ~ 41 ka period. The Mendel Formation sedimentary sequence is comprised of at least two glacial periods and one interglacial period. Sea level rise at the northern tip of the Antarctic Peninsula between glacial lowstand and interglacial highstand was more than 50 m during the late Miocene and was followed by a subsequent sea level fall of at least the same magnitude. The presence of well-preserved, articulated pectinid bivalves support “interglacial” open sea conditions. The re-deposition of palaeontological material was shown to be important for the Mendel Formation. Reworked pectinid shells revealed an open marine “interglacial” condition in this part of the Antarctic Peninsula during the Early to Mid Miocene (20.5–17.5 Ma). Unfortunately, relevant sedimentary deposits have not been found on land.

Geochemical and petrologic studies on Paleogene basanites from the Carpatho-Pannonian region (Poiana Rusca, Romania) and associated peridotite xenoliths provide information about the composition of the underlying lithosphere, the petrogenetic evolution of the magma and its mantle source, as well as the geodynamic significance of the igneous activity in a regional context. Major and trace elements as well as Sr–Nd isotopic ratios reveal an ocean–island basalt signature, interpreted as the derivation from an upper mantle source chemically similar to the European Asthenospheric Reservoir after low fraction partial melting. Due to estimated average mantle source temperatures and the absence of any subduction-related geochemical features, the igneous activity in Poiana Rusca was apparently triggered by adiabatic decompression melting, as postulated for similar and nearly coeval alkaline rocks in eastern Serbia. Differentiation processes within the Poiana Rusca magmatic suite initially resulted from removal of mainly olivine, followed by olivine + clinopyroxene fractional crystallization. The spinel-lherzolitic to harzburgitic composition of the mantle fragments point to 2–30% fractional melting at a depth of approx. 70 km. Petrographic and geochemical investigations indicate both cryptic and modal metasomatism related to the influence of both alkaline-rich silicate and alkaline-rich hydrous silicate melts rather than subduction-related fluids/melts.

Annual growth rings of a common hardwood species, Picea abies L., were investigated as a potential archive of past atmospheric Pb pollution. Wide distribution of trees in terrestrial settings and straightforward chronology are two advantages of this potential geochemical archive, but several processes described in the literature may obscure the trends in past Pb deposition. These confounding factors include, e.g., radial post-depositional mobility of Pb in xylem, and ecosystem acidification leading to higher bioavailability of Pb. One- to five-year annual wood increments were analyzed for Pb concentrations and 206Pb/207Pb ratios at Jezeri (JEZ), Uhlirska (UHL) and Na Lizu (LIZ), three sites in the Czech Republic, differing in atmospheric Pb loads. Three to four trees per site were included in the study. Distinct Pb concentration maxima between 1960 and 1990 at the two heavily polluted sites (JEZ and UHL) coincided with historical Pb emissions known from inventories of industrial production. No Pb concentration maxima were found at one site, LIZ, situated in a national park 150 km from major pollution sources. Spruce tree rings from JEZ, located just 5 km from coal-burning power stations, contained a large proportion of coal-derived Pb (a high-206Pb/207Pb ratio of 1.19). A coal-related maximum in 206Pb/207Pb in JEZ tree rings was found using two different analytical techniques, laser-ablation multi-collector ICP MS, and single-collector sector-field ICP MS. In a three-isotope graph (206Pb/207Pb vs. 208Pb/207Pb), tree-ring data plotted into the field of ombrotrophic (i.e., rain-fed) peat bogs, suggesting negligible contribution of bedrock-derived Pb in the xylem. We concluded that none of the potential confounding factors played a major role at our sites. Annual growth rings of P. abies in Central Europe faithfully recorded historical changes in atmospheric Pb depositions.

Northeast Africa 003 (NEA 003) is a lunar meteorite found as a two paired stones (6 and 118 g) in Libya, 2000 and 2001. The main portion (∼75 vol%) of the 118 g meteorite, used for this study, (NEA 003-A) consists of mare-basalt and a smaller adjacent portion (∼25 vol%) is a basaltic breccia (NEA 003-B). NEA 003-A has a coarse-grained magmatic texture consisting mainly of olivine, pyroxene and plagioclase. The late-stage mineral association is composed mainly of elongated plagioclase, ilmenite, troilite, fayalite, Si–K-rich glass, apatite, and a rare SiO2 phase. Other accessory minerals include ulvospinel, chromite, and trace Fe–Ni metal. Olivine and pyroxene contain shock-induced fractures, and plagioclase is completely converted into maskelynite. The Fe/Mn values of the whole rock, olivines and pyroxenes, and the bulk-rock oxygen isotopic composition provide evidence for the lunar origin of NEA 003-A meteorite. This is further supported by the presence of Fe–Ni metal and the anhydrous mineral association. NEA 003-A is geochemically and petrographically distinct from previously described mare-basalt meteorites and is not paired with any of them. The petrography and major element composition of NEA 003-A is similar to the composition of low-Ti olivine mare basalts from Apollo 12 and olivine-normative basalts from Apollo 15. The NEA 003-A meteorite shows obvious geochemical similarities in trace elements contents with Apollo 15 olivine-normative basalts and could represent a yet unknown geochemically primitive member of the olivine-normative basalt series. The meteorite is depleted in rare earth elements (REE) and incompatible trace elements indicating a primitive character of the parental magma. The bulk-rock chemical composition demonstrates that the parent melt of NEA 003-A was not contaminated with KREEP components as a result of magma mixing or assimilation processes. Results of crystallization modelling and low minimum cooling rate estimates (∼0.07 °C/h) suggest that the parent melt of NEA 003-A crystallized in the lower part of a lava flow containing cumulate olivine (∼10%) and was probably derived from more primitive picritic magma by fractional crystallization processes. Sm–Nd dating yields an age of 3.09 ± 0.06 Ga which corresponds to the period of lower Eratosthenian lunar volcanic activity, and the near-chondritic eNd value of −0.4 ± 0.3 indicates that the meteorite could be derived from a slightly enriched mantle source similar to the Apollo 15 green glasses. Ar–Ar step release results are inconsistent with Sm–Nd ages suggesting that NEA 003-A was exposed to one or more impact events. The most extensive event took place at 1.8 Ga and the shock intensity was likely between 28 and 45 GPa. The absence of solar Ar suggests that NEA 003-A has not been directly exposed at the lunar surface but the cosmic ray exposure age of 209 ± 6 Ma suggests that NEA 003-A resided in the upper regolith for part of its history.

We present a comprehensive geochemical data set for a suite of back-arc alkaline volcanic rocks from James Ross Island Volcanic Group (JRIVG), Antarctic Peninsula. The elemental and isotopic (Sr, Nd, Pb and Li) composition of these Cenozoic basalts emplaced east of the Antarctic Peninsula is different from the compositions of the fore-arc alkaline volcanic rocks in Southern Shetlands and nearby Bransfield Strait. The variability in elemental and isotopic composition is not consistent with the JRIVG derivation from a single mantle source but rather it suggests that the magma was mainly derived from a depleted mantle with subordinate OIB-like enriched mantle component (EM II). The isotopic data are consistent with mantle melting during extension and possible roll-back of the subducted lithosphere of the Antarctic plate. Magma contamination by Triassic–Early Tertiary clastic sediments deposited in the back-arc basin was only localized and affected Li isotopic composition in two of the samples, while most of the basalts show very little variation in δ 7 Li values, as anticipated for “mantle-driven” Li isotopic composition. These variations are difficult to resolve with radiogenic isotope systematics but Li isotopes may prove sensitive in tracking complex geochemical processes acting through the oceanic crust pile, including hydrothermal leaching and seawater equilibration.

Laser ablation inductively coupled plasma mass spectrometry (LA ICP—MS) is a newly established technique that is capable of in-situ U(Th)—Pb dating of accessory minerals in a wide range of rock types and geological environments. Recent developments in laser technology and mass spectrometry have led to substantial improvements in precision and accuracy of isotopic ages obtained by LA ICP-MS. Despite the advancements in technology, the precision and accuracy of U(Th)—Pb laser ablation ICP-MS dating are still limited by laser-induced elemental fractionation of Pb and U. This paper reviews the technique's history and summarizes recent achievements and possible future developments of this novel dating method.

Zircon fission-track (FT) and U–Pb analyses were performed on zircon extracted from a pseudotachylyte zone and surrounding rocks of the Asuke Shear Zone (ASZ), Aichi Prefecture, Japan. The U–Pb ages of all four samples are ∼ 67–76 Ma, which is interpreted as the formation age of Ryoke granitic rocks along the ASZ. The mean zircon FT age of host rock is 73 ± 7 (2 σ ) Ma, suggesting a time of initial cooling through the zircon closure temperature. The pseudotachylyte zone however, yielded a zircon FT age of 53 ± 9 (2 σ ) Ma, statistically different from the age of the host rock. Zircon FTs showed reduced mean lengths and intermediate ages for samples adjacent to the pseudotachylyte zone. Coupled with the new zircon U–Pb ages and previous heat conduction modeling, the present FT data are best interpreted as reflecting paleothermal effects of the frictional heating of the fault. The age for the pseudotachylyte coincides with the change in direction of rotation of the Pacific plate from NW to N which can be considered to initialize the NNE–SSW trending sinistral–extensional ASZ before the Miocene clockwise rotation of SW Japan. The present study demonstrates that a history of fault motions in seismically active regions can be reconstructed by dating pseudotachylytes using zircon FT thermochronology.

The provenance of Cretaceous to Paleocene sandstones from the Norwegian Sea has been determined by laser ablation ICPMS U–Pb and Pb–Pb dating of detrital zircons. The zircon grains were extracted from sandstones sampled in the More and the Voring Basins. The potential source regions for the Norwegian Sea sediments are the surrounding landmasses of East Greenland and Norway. The basement of East Greenland contains both Archaean (3800–2500 Ma) and Early Proterozoic (ca. 2000 Ma) rocks, whereas the main Norwegian basement ages are younger (1000–1600 Ma). Sandstones of known provenance, derived from East Greenland and the Norwegian landmasses, have been analysed for comparison with the investigated sandstones of unknown provenance. The analysed detrital zircons derived from the East Greenland and Norwegian landmasses reflect the known basement ages as the sandstones derived from East Greenland are characterized by a wide detrital zircon age pattern with a considerable Archaean component. The Norwegian-derived detrital zircons show a narrow age pattern with the age maxima between 1000 and 1600 Ma. The Turonian–Maastrichtian sandstone samples from the Voring Basin show wide-range zircon age patterns, all with a discernible Archaean component, indicating an East Greenland provenance. A sample of Cenomanian sandstone from the Donna Terrace, located on the eastern flank of the Voring Basin, shows a narrower detrital zircon age pattern typical of sediments derived from the Norwegian landmass. Sandstones of Maastrichtian–Paleocene ages in the More Basin show zircon age patterns that are indicative of an eastern source, whereas a Coniacian sandstone sample from the More Basin shows detrital zircon age spectra typical of a western source. The provenance change from a western to an eastern source found in the More Basin sandstones was most likely a result of the Baltic margin elevation during Coniacian to Maastrichtian times, resulting in an increased sediment supply from the eastern margin.

Volcanics of the Skinner Cove Formation of western Newfoundland carry a primary remanence acquired at 550 Ma at a paleolatitude of 19°S. There has been doubt that this represents the latitude of the Laurentian margin at 550 Ma, because the Skinner Cove Formation is allochthonous. We present new evidence from inherited zircons in the volcanics that should remove this doubt. Zircon crystals extracted from an ankaramite flow and a trachyte flow were dated individually by measuring U–Th–Pb isotopes for ∼ 30 μm ×30 μm areas using a laser ablation microprobe (LAM) linked to an inductively coupled plasma mass spectrometer (ICP-MS). Most of the zircons from the ankaramite are concordant and yield a 550±5 Ma date indistinguishable from the 550+3/−2 Ma date previously reported using multi-grain thermal ionisation mass spectrometry. About half of the zircons from the trachyte are also concordant yielding an overlapping date of 556±5 Ma. The other half clustered at ∼1000 and 1500–1600 Ma, which are characteristic ages of the Grenvillian basement exposed nearby in the Long Range Inlier. These zircon xenocrysts were very likely picked up as the Skinner Cove magma ascended through Grenvillian basement of the Laurentian margin. There can now be little doubt that the ∼19°S Skinner Cove paleolatitude represents Laurentia’s southern margin at 550 Ma. This makes it unlikely that Laurentia changed from south polar at ∼523 Ma to equatorial at ∼508 Ma due to a rapid ∼90° change in the Earth’s rotation axis. Such an inertial interchange true polar wander (IITPW) event has been proposed as a trigger for the Cambrian faunal explosion. An IITPW event may have occurred in the Vendian, mostly between 577 and 565 Ma, judging by paleomagnetic results from Laurentia. However, it is more likely that the paleomagnetic results suggesting high latitude for Laurentia at 577 Ma or low latitude at 565 Ma are flawed. We suggest that Laurentia remained at low latitude throughout the Vendian (from the ∼600 Ma start of near-equatorial glaciations). This is supported by magmatic evidence suggesting that Laurentia’s incipient Iapetus margin was stationary over a mantle plume throughout the Vendian. Laurentia at low latitude throughout the Vendian also helps provide the predominance of low latitude continents needed to account for the Vendian’s near-equatorial glaciations, according to the snowball Earth hypothesis.

New developments in U–Pb dating of zircons by laser ablation (LA) ICPMS are described and, for the first time, a direct comparison of detrital zircons dated by LA ICPMS and SIMS methods is presented. True real-time mass bias correction is made by aspirating a Tl/U tracer at the same time as laser ablation. The method is similar to that described in Horn et al. (2000) , except that enriched 233U rather than 235U is used in the tracer solution. Correction for laser-induced Pb/U elemental fractionation is based on a mathematical treatment of time-resolved data that is independent of laser ablation characteristics and does not require external standardisation. Internal corrections for mass bias and elemental fractionation eliminate the effects of variable sample matrix on isotopic ratios and improve the accuracy of U–Pb dating by laser ablation ICPMS. With the proper error propagation, the precision of U–Pb age determinations is only slightly worse than SIMS-based ion probe dating. However, LA ICPMS is capable of much more rapid analysis of the large number of zircons required for sediment provenance studies. There is excellent agreement between concordant laser ablation ICPMS and SIMS analyses of detrital zircons extracted from lower Silurian metasandstone from the Ulven Group (Skarfjell Formation) in the west Norwegian Caledonian nappes. Both LA ICPMS and SIMS U–Pb zircon ages indicate that sedimentary detritus of the Ulven Group was supplied from a terrain containing zircons of Archean, Proterozoic and early Ordovician age.

Precise measurements of the isotopic composition of Li in low-concentration natural carbonate samples is demonstrated for quadrupole ICPMS. Cool plasma conditions result in high sample/background ratios for the measured Li signals even for low concentrations. Quantitative chemical separation of Li prior to the measurement on ICPMS is necessary to avoid the matrix-induced isotopic fractionation and the results have to be externally corrected for mass bias and instrumental fractionation. The isotopic composition of lithium can be measured in samples containing only 5–10 ng Li with a within-run precision better than 0.5‰ (2 standard errors of the mean), and a long term reproducibility that is better that 2.1‰ (2 standard deviations). The method has been successfully used to measure Li isotopic composition of 1–10 mg samples of calcium carbonate tests of Pulleniatina obliquiloculata and Globorotalia tumida that were collected from the sediment–seawater interface and have Li concentrations of about 1 ppm. The isotopic composition of Li in studied calcium carbonate tests of P. obliquiloculata is independent of the size of tests and resembles the lithium isotopic composition of modern seawater, suggesting that this species may provide a record of Li isotope variations in past oceans.

High-precision garnet chronometry using the Sm–Nd, U–Pb, Rb–Sr or Lu–Hf isotope systems is gaining widespread application for constraining the prograde and high-temperature history of metamorphic belts. However, due to the low concentrations of the chronometrically important elements, garnet analyses are often susceptible to incorporation of small quantities of accessory phases such as zircon, monazite and allanite. Here we assess the extent to which such inclusions affect garnet analyses by comparing in situ analyses of Sm and Nd concentrations in the crystal lattice, obtained by laser ablation inductively coupled mass spectrometry (LA-ICP-MS), with those obtained by isotope dilution (ID) on separates of the same garnets. The results show that the garnets studied here are largely free from inclusions. In general, however, the low concentrations of Sm and Nd in the garnet lattice mean that the incorporation of even very small quantities of accessory phases will result in a significant change in the measured garnet Sm and Nd concentration. Simple modelling of the effect of such inclusions on age information shows that garnet inclusion disequilibrium and the extent to which inclusions decrease the apparent parent–daughter ratio are critical. Such modelling demonstrates that the incorporation of old LREE-enriched minerals such as monazite will yield an apparently lower age than the true garnet age. However, this study indicates that erroneous age information can be identified if duplicate garnet analyses are performed. In addition, LA-ICP-MS is shown to be a useful technique in verifying the purity of samples for isotope analysis.