"New software for processing LA-ICP-MS data for mineral deposit applications." Applied Earth Science, 126(2), pp. 45–46

Major and trace element chemistry has been determined in the main minerals (olivine, orthopyroxene, clinopyroxene, plagioclase, amphibole, phlogopite) from the Talavera and La Solanilla gabbroic intrusions (Spanish Central System). The results show a heterogeneous mineral composition illustrative of the chemical evolution of calc-alkaline basic magmas during crystallization. The formation of incompatible element-rich interstitial minerals, such as amphibole, phlogopite and accessory phases (e.g., zircon, apatite), and the presence of zoning patterns in major minerals towards a more evolved composition, point to a progressive differentiation of the parental melt. The chemical variation depicted by trace elements usually incompatible with clinopyroxene (e.g., rare earth elements (REE), Th, Zr, Nb, Ti) implies co-precipitation with phases displaying a compatible behaviour with respect to these elements (e.g., apatite, zircon, amphibole). However, the very high LILE (large ion lithophile elements) and LREE (light REE) shown by clinopyroxene can not be explained exclusively by a closed-system in-situ crystallization process. Several features of the mineral chemistry (e.g. positive correlation of (La/Sm)(N) with La and Na in clinopyroxene and plagioclase, respectively) support the involvement of an external component (wall-rock assimilation or hybridization with an evolved melt). The petrography and mineral chemistry of the gabbros, in conjunction with bulk rock data from previous studies, favour a calc-alkaline affinity for the parental melts. Thus, metasomatism in the mantle sources related with this basic magmatism might be associated with recycling of crustal components during the Variscan orogeny.

Oxo-magnesio-hastingsite, ideally NaCa2(Mg2Fe33+)(Al2Si6)O22O2, is a new anhydrous amphibole from the Deeti volcanic cone in the Gregory rift (northern Tanzania). The mineral occurs as megacrysts up to 12 cm in size in crystal-rich tuff. Oxo-magnesio-hastingsite is brown with a vitreous lustre and has a perfect {110} cleavage. The measured density is 3.19(1) g/cm(3). Ferri-kaersutite is biaxial (-), alpha = 1.706 (2), beta = 1.715(2), gamma = 1.720(2) (Na light, 589 nm). 2V (calc.) = 73 degrees. Dispersion: r > v, weak; orientation: Y = b;Z(boolean AND)c = 8 degrees; pleochroism: strong, Z: dark brown, Y: brown, X: light brown. The average chemical formula of the mineral derived from electron microprobe analyses, Mossbauer spectroscopy and direct water determination is (Na0.67K0.33)(Sigma 1.00)(Ca1 87Na0.14Mn0.01)(Sigma 2.02)(Mg3.27Fe1.253+Al0.08)(Sigma 5.04)(Al1.80Si6.20O22)(O1.40OH0.60)Sigma(2.00). It has monoclinic symmetry, space group C2/m and unit-cell parameters a = 9.8837(3), b = 18.0662(6), c = 5.3107(2) angstrom, beta = 105.278(1)degrees, V = 914.77(5) angstrom(3), Z = 2. The five strongest powder-diffraction lines [d in angstrom, (I/Io), hkl] are: 3.383 (62) (131), 2.708 (97) (151), 2.555 (100) ((2) over bar 02), 2.349 (29) ((3) over bar 51) and 2.162 (36) (261). The isotopic composition of H and O, as well as the concentration of trace elements in oxo-magnesio-hastingsite suggest its formation from a melt originated from a mantle source metasomatized by slab-derived fluids.

A suite of post-tectonic granitoids (mostly peraluminous, broadly I-type granodiorites and monzogranites) and mafic rocks from NW Iberia with crystallization ages between ca. 309 and 290Ma has been investigated for Sm–Nd isotopes and inherited zircon content in order to constrain the nature of their source rocks. εNd values (at 300Ma) vary from −0.2 to −5.9 and TDM values range from 1.01 to 1.58Ga. Inherited (xenocrystic) zircons yielded ages ranging from 458 to 676Ma, with 90% of data between 490 and 646Ma, corresponding to Neoproterozoic (mostly Ediacaran), Cambrian and Ordovician ages. Only three highly discordant analyses yielded ages older than 650Ma. Based on the data reported herein and relevant data from the literature we contend that post-tectonic granitoids of the Iberian Variscan Belt (with exception of the scarce anatectic S-type granitoids) were derived mostly from metaigneous lower crustal sources which in turn were ultimately derived from a subcontinental lithospheric mantle enriched between ca. 0.9 and 1.1Ga. I-type granitoids and mantle-derived mafic rocks both underwent varying degrees of contamination by a metasedimentary lower crust depleted in pre-650Ma zircon (through previous melting episodes) with a time-integrated Sm–Nd evolution different to that of the metaigneous lower crust. Participation of this metasedimentary crust in the genesis of these granitoids may account for Nd isotopic variability and Nd model ages well in excess of 1.2Ga.

Spinel lherzolite xenoliths from the Cenozoic Calatrava volcanic field provide a sampling of the lithospheric mantle of central Spain. The xenoliths are estimated to originate from depths of 35-50 km. Trace element content of clinopyroxene and Cr-number in spinel indicate low degrees of partial melting (<= 5%) of the xenoliths. Although a major element whole-rock model suggests wider degrees of melting, the Calatrava peridotite chemistry indicates a moderately fertile mantle beneath central Spain. Calatrava peridotite xenoliths bear evidence for interaction with two different metasomatic agents. The enrichment in LREE (light rare earth element), Th, U and Pb, and the negative anomalies in Nb-Ta in clinopyroxene and amphibole from xenoliths of El Aprisco, indicate that the metasomatic agent was probably a subduction-related melt, whereas the enrichment in MREE in clinopyroxene from xenoliths of the Cerro Pelado centre suggests an alkaline melt similar to the host undersaturated magmas. These metasomatic agents are also consistent with the chemistry of interstitial glasses found in xenoliths of the two volcanic centres. Differences in metasomatism but also in mantle composition is supported by Sr-Nd whole-rock data, which show a more radiogenic nature for Sr isotopes of samples from the El Aprisco centre (Sr-87/Sr-86 ratios of 0.7035-0.7044 instead of 0.7032-0.7037 for samples from Cerro Pelado). The timing of the subduction-related metasomatic stage is unconstrained, although the Calatrava intraplate volcanism intrudes an old Variscan lithospheric section reworked during the converging plate system affecting SE Iberia in the Tertiary. The presence of wehrlite types within the Calatrava peridotite xenoliths is here interpreted as a reaction of host lherzolites with silica-undersaturated silicate melts that could be related to the Calatrava alkaline magmatism. The Sr-Nd isotopic composition of Calatrava peridotites plot within the European asthenospheric reservoir (EAR) mantle, these values represent more enriched signatures than those found in the other Spanish Cenozoic alkaline province of Olot.

Alkali carbonates nyerereite, ideally Na2Ca(CO3)2 and gregoryite, ideally Na2CO3, are the major minerals in natrocarbonatite lavas from Oldoinyo Lengai volcano, northern Tanzania. They occur as pheno- and microphenocrysts in groundmass consisting of fluorite and sylvite; nyerereite typically forms prismatic crystals and gregoryite occurs as round, oval crystals. Both minerals are characterized by relatively high contents of various minor elements. Raman spectroscopy data indicate the presence of sulfur and phosphorous as (SO4)2− and (PO4)3− groups. Microprobe analyses show variable composition of both nyerereite and gregoryite. Nyerereite contains 6.1–8.7 wt % K2O, with subordinate amounts of SrO (1.7–3.3 wt %), BaO (0.3–1.6 wt %), SO3 (0.8–1.5 wt %), P2O5 (0.2–0.8 wt %) and Cl (0.1–0.35 wt %). Gregoryite contains 5.0–11.9 wt % CaO, 3.4–5.8 wt % SO3, 1.3–4.6 wt % P2O5, 0.6–1.0 wt % SrO, 0.1–0.6 wt % BaO and 0.3–0.7 wt % Cl. The content of F is below detection limits in nyerereite and gregoryite. Laser ablation ICP-MS analyses show that REE, Mn, Mg, Rb and Li are typical trace elements in these minerals. Nyerereite is enriched in REE (up to 1080 ppm) and Rb (up to 140 ppm), while gregoryite contains more Mg (up to 367 ppm) and Li (up to 241 ppm) as compared with nyerereite.

Northern Norrbotten, Sweden is a key part of Baltic Shield and provides a record of magmatic, tectonic and related, superimposed, Fe oxide-apatite and iron oxide-copper-gold (IOCG) mineralization, during the Svecokarelian orogeny. Titanite and allanite from a range of mineral deposits in the area have been analysed for U-Pb isotope systematics and trace element chemistry using laser ablation quadrupole inductively coupled plasma-mass spectrometry (LA-ICP-MS). Analyses of a single sample from the regional scapolite-albite alteration give an age of 1903 +/- 8 Ma (2 Sigma) and may be contemporaneous with the early stages of Fe mineralization (1890-1870 Ma). Analyses of titanite and allanite from undeformed IOCG deposits indicate initial alteration at 1862 +/- 16 Ma. In many deposits subsequent metamorphic effects reset titanite isotope systematics from 1790 to 1800 Ma, resulting in a spread of U-Pb isotope analyses along concordia. In some instances core regions may record evidence of early thermal events at around 2050 Ma. Titanite and allanite from deformed IOCG deposits on major shear zones record ages from 1785 +/- 21 Ma to 1777 +/- 20 Ma, corresponding to deformation, metamorphism and secondary hydrothermal alteration as a result of late orogenic movements. The lack of intracrystalline variations in titanite and allanite trace element chemistry suggests that hydrothermal fluid chemistry and metal source were the main controls on mineral trace element chemistry. Titanite from undeformed Fe oxide-apatite and IOCG deposits is typically light rare earth element (LREE) enriched, and shows low U/Th ratios and low Ni in both intermediate to acid and basic volcanic-hosted deposits. This is consistent with a granitic source for metals. Minor variations in trace element patterns are consistent with the influence of aqueous complex formation on relative REE solubility. Deposits related to the Nautanen Deformation Zone have relatively heavy REE (HREE)-enriched titanite, and LREE-depleted allanite, with high U/Th ratios and elevated Ni contents, consistent with leaching of metals from the local basic volcanic rocks. All hydrothermal titanites are high field strength element enriched (Nb, Ta, Zr) indicating their transport as a result of either high salinities or high F contents, or both. The data overall support models of IOCG-type mineralization as a result of regional circulation of saline hydrothermal fluids in association with major crustal structures, with at least some metallic components derived from the granitoid rocks of the area. All the deposits here show evidence of subsequent metamorphism, although penetrative fabrics are restricted to regional-scale deformation zones.

Recent field work and mapping in the lower units of the Cabo Ortegal Complex provided new data about the tectonic melange that appears in the lowest structural position: the Somozas Melange. This melange unit with average thickness of 1800 m is restricted to the eastern part of the complex, and is located at the advancing front of the allochthonous complexes of NW Iberia. Three rock units are involved in the melange: 1) an ophiolitic melange consisting of igneous rocks mixed with serpentinites; 2) a metasedimentary unit with phyllites and phyllonites, with scarce conglomerates, marbles and quartzites; 3) high-T metamorphic rocks with varied types of amphibolites and orthogneisses.Two granitic rocks within the ophiolitic melange were dated using U-Pb zircon geochronology at 527 +/- 2 Ma and 499 +/- 1 Ma. Two different series of igneous rocks can be distinguished in this melange. The first series consists of gabbros, diorites, granitoids and basalts-basaltic andesites with calc-alkaline affinities. The second series contains common basaltic rocks, diabasic dikes and gabbros with chemical compositions typical of island-arc tholeiites. Both igneous series shared a common geographic setting, but the island-arc tholeiites are younger than the calc-alkaline igneous rocks. The two igneous series were probably generated in a mature volcanic arc located along the periphery of Gondwana. In the metasedimentary unit, a conglomerate from a large tectonic block included in serpentinites yielded age populations of detrital zircons suggesting that the sediments were deposited along the periphery of the West-African Craton. This conglomerate contains a large number of zircons (n = 24) with ages ranging 630-464 Ma, probably representing the chronology of the Pan-African event, including the magmatic activity in the volcanic arc where the igneous lithologies involved in the melange were generated. The maximum age of sedimentation for this conglomerate is estimated as latest Cambrian - earliest Ordovician, and constraints the end of the magmatic activity in the volcanic-arc. Within the unit of high-T rocks, an orthogneiss yields a U-Pb protolith age of 485 +/- 6 Ma, which is similar to other ages of igneous rocks in the basal allochthonous terrane in NW Iberia. The three rock assemblages forming part of the Somozas Melange may be linked to the evolution of a mature peri-Gondwanan volcanic arc. This volcanic arc was affected by pronounced extension which caused the opening of intra-arc basins, culminating the rifting and subsequent drift of the external parts of the arc during the opening of the Rheic Ocean. This opening started during a time interval constrained by the peak activity in a mature volcanic arc (c. 527-499 Ma) and the generation of intra-arc basins around the Cambrian-Ordovician boundary.Tectonic melanges including high-P rocks have been classically related to subduction zone environments. Regional relationships in NW Iberia and the nature of the rock units involved in the Somozas Melange, suggest that two different subduction zones generated during oblique convergence and collision between Gondwana and Laurussia were active during the final stages of the assembly of Pangea. The first related to the underthrusting beneath Laurussia of the most external Gondwana margin (c. 370 Ma). The second subduction zone was a new one which accreted later remnants of a peri-Gondwanan arc and sediments of the continental margin below a layer of exhumed high pressure rocks. This oblique collision finished the closure of the Rheic Ocean and contributes to define the new oceanic domain located to the East of Pangea, the Palaeotethys.

In sedimentary provenance analysis, a fundamental question is the age of a crystalline source rock and the timing of subsequent thermotectonic events that affected crystalline terrains prior to exhumation and erosion. Zircon is a useful detrital mineral which carries a wealth of information about the petrogenesis, geochronology, alteration, and cooling history of its source rocks, but only few attempts were made so far to combine such data from single grains. We present an approach combining fission track (FT) and in-situ LA–ICPMS U/Pb isotopic analyses from the same grain. Detrital zircons were dated by the FT method, and grain interiors were imaged by SEM-CL to avoid ablation of inherited or other unsuitable domains. Precise and accurate U/Pb isotopic compositions were determined by a simple setup consisting of a 213 nm Nd:YAG laser source, coupled to a quadrupole ICPMS instrument. Our results are significant for at least two reasons: (1) The U/Pb analytical protocols provide an excellent trade-off between analysis quality and a high, cost-effective sample throughput (70-100 zircon grains per day). CL-control and a good spatial resolution aid in reducing age bias, as judged from the notably high proportion (>90%) of concordant (±5%) grain ages. (2) The double dating approach yields valuable insights into the thermal history of source terrains of Dinaride synorogenic sediments. Several clusters of age-pairs can be isolated that identify Alpine tectonostratigraphic units. Given that basement geochronology is known in detail, several source terranes can be pinpointed with a high level of confidence that is normally not achieved by using the two dating techniques separately. A majority of the grains indicating Late Cretaceous overprint is derived from the Austroalpine and/or Tisza Units as this thermal event is not recorded in the Central and Northern Dinarides. Our results clearly demonstrate the mixing of sediments derived from exhumed source areas that previously underwent fundamentally different thermal histories. In the light of new biostratigraphic results indicating post-Eocene depositional age for the outer Dinaride foreland basin sediments and suggesting a complex sediment reworking pattern (Mikes et al. 2008), ambiguous heavy mineral data from these sediments can be re-interpreted in terms of a large-scale dispersal history involving the Pelagonides and the Austroalpine/Tisza Units as the major sedimentary source areas.

The Tri-State and Northern Arkansas districts of the Ozark plateau, North America, are both classic examples of Mississippi Valley-type (MVT) mineralization, formed by continent-scale basinal brine migration as a result of the uplift of the Arkoma foreland basin in response to the Early Permian Ouachita orogeny. The chemistry of the fluids responsible for both sulfide mineralization and gangue precipitation in these districts was studied by quantitative microanalysis of individual fluid inclusions in quartz and sphalerite using 213-nm laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Using halogen systematics, an evaporative seawater origin for the brines was determined, but higher Br concentrations suggest that the sphalerite-hosted “ore fluids” underwent a significantly greater degree of evaporation in the initial stages of fluid evolution compared to brines hosted by gangue phases. Metal contents of the brines responsible for quartz and dolomite precipitation are low compared to modern basinal brines, but many of the fluid inclusions trapped in sphalerite in both districts contained anomalously high metal concentrations, suggesting that mineralization involved incursion of a metal-rich fluid of distinct geochemistry. Examination of the multicomponent chemical characteristics revealed that dolomitization was probably an important process in the early chemical evolution of fluids that infiltrated both districts. In the Tri-State district, precipitation of sulfides was most likely driven by mixing of the metalliferous fluid with another brine, possibly rich in reduced sulfur. In northern Arkansas the compositional variations observed are best explained by local dissolution of the carbonate host rock. This may have been the process that ultimately drove sulfide deposition through fluid neutralization and reduction. Alternatively, the digestion of the host rock may have been the result of locally generated acidity produced by the deposition of sulfides. The discovery of anomalously metal-rich fluids linked to mineralization suggests that these deposits are not simply the product of typical basin evolution, helping to explain the abundance of MVT mineralization in some forelands, whereas others are barren. It is likely that a significant portion of the history of the hydrothermal flow system was characterized by the precipitation of barren gangue assemblages from metal-poor brines, with metalliferous fluids only being expelled from a specific stratigraphic package at a distinct stage of basin evolution.

An analytical protocol for rapid and reliable laser ablation-quadrupole (LA-Q)- and multi-collector (MC-) inductively coupled plasma-mass spectrometry (ICP-MS) analysis of Pb isotope ratios (207Pb/206Pb and 208Pb/206Pb) in peats and lichens is developed. This technique is applicable to source tracing atmospheric Pb deposition in biomonitoring studies and sample screening. Reference materials and environmental samples were dry ashed and pressed into pellets for introduction by laser ablation. No binder was used to reduce contamination. LA-MC-ICP-MS internal and external precisions were <1.1% and <0.3%, respectively, on both 207Pb/206Pb and 208Pb/206Pb ratios. LA-Q-ICP-MS internal precisions on 207Pb/206Pb and 208Pb/206Pb ratios were lower with values for the different sample sets <14.3% while external precisions were <2.9%. The level of external precision acquired in this study is high enough to distinguish between most modern Pb sources. LA-MC-ICP-MS measurements differed from thermal ionisation mass spectrometry (TIMS) values by 1% or less while the accuracy obtained using LA-Q-ICP-MS compared to solution MC-ICP-MS was 3.1% or better using a run bracketing (RB) mass bias correction method. Sample heterogeneity and detector switching when measuring 208Pb by Q-ICP-MS are identified as sources of reduced analytical performance.

Secondary ion mass spectrometry (SIMS) U-Pb geochronology of zircons from high-pressure granulite units within the allochthonous complexes of the northwestern Iberian Variscan belt illustrates the complexity of dating high-pressure events using the U-Pb chronometer. Zircons from four rocks belonging to the high-pressure (P), high-temperature (T) units were dated by SIMS. A gabbro body with preserved igneous texture within the Ordenes Complex high-P granulites yielded a crystallization age of ca. 515 Ma. A high-P mafic granulite within the same unit contained zircons that had U-Pb ages clustered around 387 Ma, and it preserved no record of events between the crystallization of precursor gabbros and the granulite event (sensu lato). A mafic high-P granulite from an equivalent structural unit in the Cabo Ortegal Complex contained abundant zircons that recorded crystallization of igneous protolith at 490-520 Ma and crystallization of new zircon from a melt phase starting at ca. 404 Ma, and zircons with Pb-206/U-238 ages between ca. 480 and 430 Ma that are interpreted to reflect partial Pb loss during the granulite-facies event. Bright luminescent cores in zircons from a leucosome pod within the outcrop area of the latter granulite yielded a mean age of 397 Ma, whereas dark U-rich rims in zircons from this leucosome yielded a mean age of 390 Ma. These data, in conjunction with previous isotope dilution-thermal ionization mass spectrometry (ID-TIMS; zircon, monazite, titanite) U-Pb ages and Ar-40/Ar-39 dating of fabrics from rocks within the same units, point to a Silurian age for the high-P metamorphism. Timing of the peak pressure cannot be further constrained with available data because, in this case, we infer that the U-Pb system in zircon recorded only a segment of the retrograde path. We suggest that the high-P metamorphic event is related to the accretion and understacking of these units to the margin of Baltica or Laurentia following the closure of the Iapetus or Tornquist Oceans and concomitant opening of the Rheic Ocean.

Analysis of human tooth enamel using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) provides a basis for systematic evaluation of variation in the chemical composition of enamel in relation to tooth crown geometry. Analysis of thin sections allows a sampling strategy that can be cross-referenced to incremental growth structures in tooth enamel. Strontium and calcium are incorporated into developing teeth in a manner that reflects changing physiological concentrations in the body. Strontium/calcium (Sr/Ca) ratios are expected to decease at birth in breastfed infants, because the mammary gland exerts a greater activating effect on calcium transfer than the placenta. However, Sr/Ca ratios should increase at birth in infants fed on a formula derived from cow's milk. Changes in Sr/Ca ratios across the neonatal line in five out of six deciduous teeth from children of known mode of feeding within the first few months after birth conform to the predicted direction of change, indicating that changes in physiological concentrations of strontium and calcium resulting from a dietary shift during the secretory stage of enamel formation may not be completely overwhelmed during enamel maturation. Implications for the reconstruction of longitudinal records of infant diet from tooth enamel are discussed.

In situ U-Pb dating of a variety of mineral phases is an important goal in petrology. This study reports data chiefly from titanite, but also from rutile and apatite, obtained using the laser ablation (LA)-ICP-MS methodology on polished thick sections in order to retain as much petrologic information as possible, and allowing trace element analyses from adjacent areas to the U-Pb analyses. The samples analysed come from Svecofennian intermediate to acid volcanic rocks of the Porphyry Group within the major iron ore province of Norrbotten, northern Sweden, where titanite is a common phase associated with the mineralisation. Using a laser beam of 30-45 put in diameter, accurate and relatively precise (2-3% 2 sigma on Pb-206/ U-238 ratios) data can be obtained on titanite. Similar precision on Pb/U ratios can be obtained in rutile, but accuracy cannot be assessed because of the lack of well characterised standards. However, the data are a priori accurate as they are geologically reasonable. Apatite shows reverse discordance, which could be explained by a number of scenarios. However, the Pb-207/Pb-206 ages are fairly precise (1-3% 2 sigma) and the calculated age is geologically reasonable, suggesting that the data may be accurate.The titanite grains studied show complex internal structures. Rare earth element (REE) analysis by LA-ICP-MS demonstrates that the core and rim zones are distinct and supports a model for two-stage evolution in two out of three samples, with the rims in these samples being enriched in total REE, and particularly in LREE in one sample, and displaying a positive Y-anomaly in contrast to the cores. In situ U-Pb analysis reveals that core zones from all samples retain distinct older ages of c.2050 Ma, whereas the reworked rims have either distinct younger or strongly reset ages. The older cores are interpreted as representing the first alteration/metamorphism of the volcanic pile. Titanite rims record a U-Pb age of 1870 +/- 24 Ma (2 sigma) at Luossavaara, and 1826 +/- 15 Ma (2u) at the smaller Fe oxide-apatite body at Gruvberget. In both cases, the ages are consistent with previous age determinations from the Fe oxide-apatite deposits. A sample from Malmberget records a slightly different scenario, where U-Pb ages spread along concordia from c. 1920 to 1708 Ma. We attribate this pattern to metamorphic reworking of primary metasomatic titanite. Rutile ages from inclusions within the core of Gruvberget titanite essentially mimic the ages obtained from the surrounding titanite and suggest that they have undergone the same history. Apatite inclusions within titanite at Malmberget record a younger age of 1584 +/- 12 Ma 2 sigma), which we attribute to later events known to have affected the area.These data indicate that the Porphyry Group volcanics must be at least c.2050 Ma in age, in contrast to previous age determinations from zircon which suggested a deposition age of c. 1960 to 18 80 Ma. The large grain size of the titanites studied, coupled with the ability for the first time to obtain in situ U-Pb ages from small areas, has allowed probing of this hitherto unrecognised event. Smaller zircon grain size, coupled with extremely saline hot, pressurised (high P-T) metasomatic fluids, relating to regional magnetite-apatite mineralisation in the period 1900 to 1800 Ma, may have resulted in resetting of zircon U-Pb systematics. (c) 2007 Elsevier B.V All rights reserved.

Thirty six element signatures were compared in historical Parmelia sulcata samples from the Natural History Museum herbarium collected over the period 1797–1967 with those recorded in the same species and tree bark sampled in 2000 from Burnham Beeches, lying 40km west of London. Nineteen elements reached highest concentrations in herbarium samples, consistent with a pollution legacy and dust contamination in the herbarium. Healthy Parmelia sampled east and down-wind of London at a farm during peak SO2 emissions in 1967 contained highest V, Ni, Zn, Cd, Se, Ge contents, supporting derivation from fuel combustion; the same sample was previously determined as having a low δ34S and high S and N contents. Lowest V, Co, Ni, Cu, Zn, Sn, Ba, Pb, Mo, Sb, Li, B, Cs, U, Th, Ga contents were recorded in a sample with a high δ34S and low S content collected in 1887 from a remote region from Ross-shire, Scotland. Se and Cd enrichment, never-the-less suggest a transboundary pollution influence. Lichen Pb concentrations from Burnham Beeches were amongst the lowest recorded in spite of lichens being collected close to roads. Herbarium samples help interpret changes in element deposition where few data exist, in spite of dust contamination.

Multi-element content and uranium (U) isotopes were investigated in the lichen Hypogymnia physodes (native and transplants) sampled across a 60-km transect, centred on Karabash smelter town, from Turgoyak Lake (SW) to Kyshtym (NE) to investigate the origin of U. Kyshtym was the site of a major nuclear accident in 1957. (234)U/(238)U activity ratios in native thalli sampled during July 2001 were within the natural isotopic ratio in minerals. Uranium/thorium (U/Th) ratios were higher in native thalli towards the NE (average 0.73) than those in the SW (average 0.57). Element signatures in native thalli and transplants suggest U was derived from fossil fuel combustion from Karabash and sources lying further to the east. Systematic and significant U enrichment indicative of a nuclear fuel cycle source was not detected in any sample. Element signatures in epiphytic lichen transplants and native thalli provide a powerful method to evaluate U deposition.