Stephan M. Weise

An active subcontinental mantle volatile system in the western Eger rift, Central Europe: gas flux, isotopic (He, C, and N) and compositional fingerprints

The composition and flux of gas emanations, and the isotopic ratios of CO2, He and N2 of 74 mineral springs and dry gas vents (mofettes) in the western Eger rift (Czech Republic) have been analyzed. Four geochemically similar, but tectonically separate, gas escape centers are distinguishable, out of which 3 show a free gas flux >85000 dm3 h−1. All gases from the centers are CO2-rich (>99 vol.%) and have δ13C values ranging from −1.8 to −4.0‰. 3He/4He ratios are as high as R/Ra = 5, and are among the highest measured in Europe. The discharge of the gas mixture decreases with distance from the emanation centers with both decreasing fractions of CO2 and δ13C values, whereas the fractions of N2 and trace gases increase. These changes in chemical and isotopic composition are associated by a decrease in R/Ra ratios from about 5 in the centers to <2 in the peripheries. The changes of the contents and isotopic composition of CO2 can be explained by physico-chemical fractionations of CO2 between gaseous and aqueous phases. Towards the periphery, the contents of free CO2 and its δ13C are reduced by dissolution of CO2 in groundwater, whereby the content of N2 increases. 3He/4He ratios give evidence for mixing of He from both a deep-seated magmatic and a crustal source. The gas emanation centers, with their strongly magmatic δ13C value of about −2.7‰, seem to outline the intersections of the Eger rift and the Marianske Lazně fault, which are considered to represent a deep-reaching fracture system that enables the ascent of gases from a magmatic body in the European subcontinental mantle (SCM). Therefore, the European SCM is suspected to be the main source of CO2. The most mantle-like He (and probably N2) occurs in the centers of gas release. The total regional gas flux in the western Eger rift is determined to be 3.6 × 108 mol a−1. When related to the investigated area of 1500 km2, flux densities greater than 0.24 × 106, 52, and 0.65 mol km−2 a−1 for CO2, N2 and He respectively are calculated.

Comprehensive inter-laboratory calibration of reference materials for delta O-18 versus VSMOW using various on-line high-temperature conversion techniques

Internationally distributed organic and inorganic oxygen isotopic reference materials have been calibrated by six laboratories carrying out more than 5300 measurements using a variety of high-temperature conversion techniques (HTC)a in an evaluation sponsored by the International Union of Pure and Applied Chemistry (IUPAC). To aid in the calibration of these reference materials, which span more than 125 per thousand, an artificially enriched reference water (delta(18)O of +78.91 per thousand) and two barium sulfates (one depleted and one enriched in (18)O) were prepared and calibrated relative to VSMOW2b and SLAP reference waters. These materials were used to calibrate the other isotopic reference materials in this study, which yielded: Reference material delta(18)O and estimated combined uncertainty IAEA-602 benzoic acid+71.28 +/- 0.36 per thousand USGS 35 sodium nitrate+56.81 +/- 0.31 per thousand IAEA-NO-3 potassium nitrate+25.32 +/- 0.29 per thousand IAEA-601 benzoic acid+23.14 +/- 0.19 per thousand IAEA-SO-5 barium sulfate+12.13 +/- 0.33 per thousand NBS 127 barium sulfate+8.59 +/- 0.26 per thousand VSMOW2 water 0 per thousand IAEA-600 caffeine-3.48 +/- 0.53 per thousand IAEA-SO-6 barium sulfate-11.35 +/- 0.31 per thousand USGS 34 potassium nitrate-27.78 +/- 0.37 per thousand SLAP water-55.5 per thousand The seemingly large estimated combined uncertainties arise from differences in instrumentation and methodology and difficulty in accounting for all measurement bias. They are composed of the 3-fold standard errors directly calculated from the measurements and provision for systematic errors discussed in this paper. A primary conclusion of this study is that nitrate samples analyzed for delta(18)O should be analyzed with internationally distributed isotopic nitrates, and likewise for sulfates and organics. Authors reporting relative differences of oxygen-isotope ratios (delta(18)O) of nitrates, sulfates, or organic material should explicitly state in their reports the delta(18)O values of two or more internationally distributed nitrates (USGS 34, IAEA-NO-3, and USGS 35), sulfates (IAEA-SO-5, IAEA-SO-6, and NBS 127), or organic material (IAEA-601 benzoic acid, IAEA-602 benzoic acid, and IAEA-600 caffeine), as appropriate to the material being analyzed, had these reference materials been analyzed with unknowns. This procedure ensures that readers will be able to normalize the delta(18)O values at a later time should it become necessary.The high-temperature reduction technique for analyzing delta(18)O and delta(2)H is not as widely applicable as the well-established combustion technique for carbon and nitrogen stable isotope determination. To obtain the most reliable stable isotope data, materials should be treated in an identical fashion; within the same sequence of analyses, samples should be compared with working reference materials that are as similar in nature and in isotopic composition as feasible.

Multi-isotopic analysis reveals individual mobility and diet at the Early Iron Age monumental tumulus of Magdalenenberg, Germany.

For the Early Iron Age western Hallstatt culture, which includes the site of Magdalenenberg in southwest Germany, it has been proposed that people were mobile and maintained far reaching social and trading networks throughout Europe. We tested this hypothesis by analyzing multiple isotopes (strontium, oxygen, sulfur, carbon, and nitrogen) of the preserved skeletons from the Magdalenenberg elite cemetery to determine diets and to look for evidence of mobility. The analysis of carbon, nitrogen, and sulfur isotope ratios in collagen of humans (n = 50) and associated domestic fauna (n = 10) indicates a terrestrial-based diet. There was a heterogeneous range of isotope values in both strontium (0.70725 to 0.71923, n = 76) and oxygen (13.4‰ to 18.5‰, n = 78) measured in tooth enamel. Although many of the individuals had values consistent with being from Hallstatt culture sites within southwest Germany, some individuals likely originated from further afield. Possible areas include the Alps of Switzerland and Austria or even locations in Italy. Our study strongly supports the assumption of far reaching social and economic networks in the western Hallstatt culture.

Age and recharge area of thermal waters in La̧dek Spa (Sudeten, Poland) deduced from environmental isotope and noble gas data

Abstract Environmental isotope and noble gas data are shown to identify the global parameters of the thermal water system in Ladek Zdroj (Spa), Sudeten, Poland. The mean 14 C age is about 5 ka, and the δ 18 O and δD data are assumed to yield the mean altitude of recharge by making use of the altitude effect known for the Sudeten area. The natural discharge rate multiplied by the 14 C age gives the total volume of water, whereas the volume of the host rock is roughly estimated for three scenarios of system dimensions. For these scenarios, the ratio of these two volumes yield a total porosity in the range of about 0.005–0.014, which, in a good approximation, should be equal to the matrix porosity. Laboratory determinations of unaltered rock samples yield a matrix porosity of 0.008 ± 0.001. For the three scenarios, the tracer age and matrix porosity are shown to yield a hydraulic conductivity for the whole system in the range 0.8–1.6 × 10 −8 m s −1 , without any knowledge of the fissure network parameters. Noble gas temperature compared with known temperature dependence yields the mean altitude of the recharge area equal to that found from the δ 18 O and δD data. The radiogenic 4 He excess and 40 Ar 36 Ar ratios are consistent with the mid-Holocene age determined from the 14 C data.

Origin and age of thermal waters in Cieplice Spa, Sudeten, Poland, inferred from isotope, chemical and noble gas data

Isotope and hydrochemical data of the thermal water system in Cieplice Ṡlaskie Zdroj (Spa) indicate the existence of two subsystems that greatly differ in volume and which meet at the fault zones of a granitic horst, where they discharge at an altitude of about 340m. One of the subsystems is very small (about 4 × 103 m3) as indicated by the tritium age of the order of 10 years and a low outflow rate. Its recharge area found from the δ18O and δD values, is about 200m above the springs, most probably on the slopes of the foothills of the Karkonosze Mountains south-southwest of the spa. The large subsystem contains water which is free of tritium and whose 14C content is from 1 to 8 pmc with δ13C = −8.0 to −9.2‰. The isotopic composition of this water reflects either the climatic effect (low-altitude recharge during a cooler pre-Holocene climate) or the altitude effect (recharge in the early Holocene period at about 1000m at the heights of the Karkonosze assuming that the 14C concentration is strongly reduced by exchange with calcite in veins). For the former hypothesis, the recharge area of this water is probably either at the foot of the southeastern slopes of the Kaczawa Mountains or/and at the foot of the Rudawy Janowickie Mountains, to the east of Cieplice. The noble gas temperatures are more consistent with the pre-Holocene recharge. Similarly, the 4He excess and 40Ar36Ar ratio support the hypothesis of a pre-Holecene age. The constant 3He4He ratio of 26 × 10−8 for highly different helium contents indicates crustal origin of helium. For the pre-Holocene age of water its volume is calculated at >- 109m3 (stagnant water in micropores and mobile water in fractures) and the hydraulic conductivity of the host granite massif is estimated at about 7 × 10−8 ms−1. Two outflows from this subsystem have different and variable fractions of a modern water component (bomb age), most probably originating from the bank infiltration of a nearby stream.

Origin and age of saline waters in Busko Spa (Southern Poland) determined by isotope, noble gas and hydrochemical methods: evidence of interglacial and pre-Quaternary warm climate recharges

Abstract In the Busko and Solec Spas, saline sulphide and sulphate waters are exploited at different depths. The shallow water system in Busko is related to an interglacial or interstadial period shown by the lack of tritium and 14 C and its δ 18 O and δD values equal to that of modern water. The noble gas temperatures (NGT) are somewhat lower than the present air temperatures, but the 4 He and 40 Ar ages of about 90–480 ka confirm a Pleistocene recharge. The δ 18 O and δD values of the deep system are much heavier than those of local modern waters, which may mean the recharge of a warm pre-Quaternary climate. The 4 He, 40 Ar and 21 Ne contents and the NGT values confirm the deep system to be recharged at the pre-Quaternary stages of the present hydrologic cycle, i.e. after the sea transgression in the Badenian. High SO 4 2− contents indicate that the Cl − and SO 4 2− in both systems originated from simultaneous leaching of NaCl and gypsum. Other components can be explained by cation exchange between water and Badenian clay minerals in marls (e.g. Ca 2+ for Mg 2+ and Na + for K + ) and by the decay of marine organic matter supplying Br − , I − and B.

Contributions of the different water sources to the Elqui river runoff (northern Chile) evaluated by H/O isotopes

We present the results of an isotope (2H and18O) and hydrogeochemical study in order to constrain the origin, recharge, and evolution of the surface and groundwater in the arid Andean realm of the Elqui watershed. The results of2H and18O analyses of water samples obtained during our summer and winter campaigns indicate a generally meteoric origin of the river and spring waters of the watershed. The isotope signature of water of the Elqui river and its tributaries as well as that of groundwater in the coastal region fits the2H‒18O relation of δ2H=7.61δ18O+6.1. A relatively fast discharge and a quasi-closed catchment area can be asserted for water along the river flow path. The tributaries from the more arid coastal area, north of the Elqui river, differ in their isotopic signature due to evaporation and hydrochemically due to interactions with the strongly altered and fractured volcanic rocks of the basement. In the Andean zone, the18O-enriched hydrothermal spring of Baños del Toro exhibits the influence of water–rock interaction processes. The chemistry of the river water changes from sulphate- to chloride-rich along the river course from the high Andean mountains to the coast. The sulphate-rich character of these Andean waters reflects their passage through sulphide-rich rock massifs that were subjected to strong oxidation processes in the near superficial environment. This sulphate signature is enforced by past and present mining of precious metal epithermal deposits (e.g. those of El Indio-Tambo Au–Cu–As district), in which mineralised zones were developed during a series of Miocene magmatic-hydrothermal episodes in the Andean realm. Owing to the proximity of the lower Elqui river waters and its tributaries to the Pacific coast, the chloride character may be induced by agricultural and marine (sea spray, fog) sources. Generally, the main source of the Elqui river water is mainly attributed to surface runoff and less to contributions from the basement fractured aquifer.

Strike-slip faults mediate the rise of crustal-derived fluids and mud volcanism in the deep sea

We report on newly discovered mud volcanoes located at ~4500 m water depth ~90 km west of the deformation front of the accretionary wedge of the Gulf of Cadiz, and thus outside of their typical geotectonic environment. Seismic data suggest that fluid flow is mediated by a >400-km-long strike-slip fault marking the transcurrent plate boundary between Africa and Eurasia. Geochemical data (Cl, B, Sr, 87 Sr/ 86 Sr, d 18 O, dD) reveal that fluids originate in oceanic crust older than 140 Ma. On their rise to the surface, these fluids receive strong geochemical signals from recrystallization of Upper Jurassic carbonates and clay-mineral dehydration in younger terrigeneous units. At present, reports of mud volcanoes in similar deep-sea settings are rare, but given that the large area of transform-type plate boundaries has been barely investigated, such pathways of fluid discharge may provide an important, yet unappreciated link between the deeply buried oceanic crust and the deep ocean.

Estimating groundwater recharge using the chloride mass-balance method in the West Bank, Palestine

Abstract The quantification of natural recharge rate is a prerequisite for efficient and sustainable groundwater resources management. Since groundwater is the only source of water supply in the West Bank, it is of utmost importance to estimate the rate of replenishment of the aquifers. The chloride mass-balance method was used to estimate recharge rates at different sites representing the three groundwater basins of the Mountain Aquifer in the West Bank. The recharge rate for the Eastern Basin was calculated as between 130.8 and 269.7 mm/year, with a total average replenishment volume of 290.3 × 106 m3/year. For the Northeastern Basin, the calculated recharge rate ranged between 95.2 and 269.7 mm/year, with a total average recharge volume of 138.5 × 106 m3/year. Finally, the recharge rate for the Western Basin was between 122.6 and 323.6 mm/year, with a total average recharge volume of 324.9 × 106 m3/year. The data reveal a replenishment potential within the estimated replenishment volumes of previous studies for the same area. Also, the range was between 15 and 50% of total rainfall, which is still within the range of previous studies. The geological structure and the climate conditions of the western slope were clearly play an important role in the increment of total volume. In some cases, such as the geological formations in the Northeastern Basin, the interaction between Eocene and Senonian chalk formations result in minimum recharge rates. Citation Marei, A., Khayat, S., Weise, S., Ghannam, S., Sbaih, M. & Geyer, S. (2010) Estimating groundwater recharge using the chloride mass-balance method in the West Bank, Palestine. Hydrol. Sci. J. 55(5), 780–791.

Stable isotopes in river waters in the Tajik Pamirs: regional and temporal characteristics

The Gunt River catchment in the Central Pamirs is a representative of the headwater catchments of the Aral Sea Basin. It covers 14,000 km2, spanning altitudes between 2000 and 6700 m a.s.l. In a monitoring network, water samples were taken at 30 sampling points every month and analysed for the stable water isotopes (18O and 2H). Our first results show δ2H values in the range from−131.2 to−94.9 ‰ and δ18O values from−18.0 to−14.0 ‰. The stable isotope patterns in the catchment seem to follow a systematic way, dominated by an altitude effect with a mean Δ δ2H=−3.6 ‰/100 m. The observed seasonal variations can be explained by geographical aspects such as the influence of different wind systems as well as melting processes.