High δD Values Research Articles

Multiple hydrothermal events at martian surface revealed by H and Cl isotope systematics of melt inclusions and hydrous minerals from chassignite NWA 2737

The chassignites and nakhlites could have co-magmatic origin but display distinct hydrogen and chlorine isotopic compositions, indicating that they may have experienced distinct hydrothermal activities on Mars. However, the details are not yet fully understood. Here, we performed H and Cl isotopic investigations on hydrous minerals (kaersutite and apatite) and glass-bearing melt inclusions from chassignite NWA 2737 to unravel the details of the hydrothermal events experienced by chassignites on Mars. Our results demonstrate that at least two hydrothermal events on Mars have been recorded in NWA 2737. A D- and 37Cl-rich martian crustal/underground fluid was added to the parent magma of NWA 2737 prior to the entrapment of melt inclusions and later interaction of the parent rock with a D-poor fluid, probably deriving from magma degassing. The notable high-δD values (up to 6239‰) of kaersutite in NWA 2737 are comparable with those recorded in younger shergottites, suggesting that the martian exchangeable water reservoir has retained a nearly constant δD value over the past 1.3 Ga.

Light δD apatites reveal deep origin water in North China Craton intracontinental granites and basalts

Water is essential to the formation of intracontinental granites, but its origin remains elusive. Here we address this scientific problem by analyzing D/H isotopes of apatites, hydrous minerals in Jurassic and Early Cretaceous granites and basalts from eastern North China Craton, where water was previously interpreted as derived from subducting slab. Results reveal extremely low δD values in pristine Early Cretaceous granitic (−203‰ to −127‰) and basaltic (−197‰ to −107‰) apatites, contrasting with relatively high δD values (−137‰ to −47‰) in Jurassic granites. Given the depth-dependent D/H isotopic fractionation during slab dehydration and high-water contents in coeval primitive mafic magmas, the Early Cretaceous magma water is attributed to the stagnant slab within the mantle transition zone. Secular change in the depth of water aligns with steepening of subducting Paleo-Pacific plate from Jurassic to Early Cretaceous, demonstrating the potential of apatite H isotopes in tracing water origin in granites and basalts.

Study on the multifractal characterization and seepage of the shale matrix: A case study of the Longmaxi Formation in southwestern Sichuan Basin, China

The pore structure and heterogeneity of shale significantly impact the occurrence and permeability of shale gas. Studying these aspects is beneficial for exploring and developing shale gas. In this study, organic-rich shale from the Longmaxi Formation in the Luzhou-Changning area was selected as the research subject. Experiments, including spontaneous imbibition, pressure saturation, and nuclear magnetic resonance, were conducted to characterize the pore structure and heterogeneity of the shale in this area. Using multifractal theory, we analyzed and discussed the multifractal characteristics of pores with different connectivities in relation to permeability. The results indicate that the T2 cutoff value (T2f) of the shale is greater than the T2c value, suggesting that the pore size of connected pores exceeds that of pores retaining bound water. The sizes of connected pores primarily range from 1 to 30 nm, predominantly between 1 and 10 nm. Significant differences were observed in the multifractal spectrum functions under dry, spontaneous imbibition, and water-saturated conditions, reflecting varying degrees of heterogeneity. The multifractal parameters differ, with higher ΔD values under water-saturated conditions, indicating that pores with weaker connectivity enhance the overall heterogeneity of the shale when saturated. Conversely, lower ΔD values under dry conditions suggest less heterogeneity in pores containing bound water. Total organic carbon (TOC) and clay content were identified as the main factors influencing the development of connected pores. Based on these findings, a discriminant 3D diagram correlating permeability with porosity, tortuosity, and multifractal parameters (D0-Dmax) of strongly connected pores was established for the Luzhou-Changning area. This diagram serves as an effective tool for evaluating the flow capacity of shale reservoirs and offers guidance for identifying sweet spots within the reservoir.

Timing of India-Asia collision and significant coupling between them around 51 Ma: Insights from the activation history of the Zhongba-Gyangze thrust in southern Tibet

Abstract Constraining the timing of tectonic coupling between converging plates is crucial for understanding the transition from continental subduction to continental collision. In the case of the India-Asia collision, thrusting of an accretionary complex onto the Indian continental margin provides the most direct temporal constraint on the early stages of continental collision, as it represents the most immediate upper-crustal fault system corresponding to plate coupling. Here, we used structural analysis combined with K-Ar dating and hydrogen isotopes of authigenic illite and muscovite to unravel the time-progressive development of the Zhongba-Gyangze thrust (ZGT), which represents a tectonic boundary fault in southern Tibet. Our results suggest that the ZGT evolved from its initiation as a single fault zone infiltrated by metamorphic fluids with high δD values (–47‰ to –55‰) at ca. 80 Ma to multiple deformation localization zones starting around 51 Ma. This latter phase is represented by the development of different generations of authigenic 1 M/1Md illite and significant input of meteoric fluids with δD values ranging from –71‰ to –98‰ through multiple episodes of brittle fault reactivation. A Late Cretaceous tectono-thermal event related to the subduction of a Neotethyan oceanic ridge may have been responsible for the formation of 2M1 illite/muscovite at ca. 80 Ma. The oldest (ca. 51 Ma) 1 M/1Md illite age coincides with the first major pulse of shortening in the upper plate after the initial India-Asia contact. Given the synchronous deceleration of India-Asia convergence, the ca. 51 Ma deformation pulse across the Yarlung-Zangbo suture zone demarcates strong coupling (i.e., the onset of continental collision) between India and Asia at this time.

Monitoring the salt stability and solvent swelling behavior of PAH‐based polyelectrolyte multilayers by quartz crystal microbalance with dissipation

AbstractThis contribution is aimed to examine the layer stability and solvent swelling behavior of polyelectrolyte multilayers (PEMs) obtained from poly(allylamine hydrochloride) (PAH), poly(styrene sulfonic acid sodium salt) (PSS), and poly(acrylic acid) against different salt solutions using Quartz Crystal Microbalance with Dissipation in terms of the solution concentration, charge type of the top layer, and PEM structure. In general, all multilayers remain stable against MgCl2 and NaCl, phosphate buffer saline, ionic liquid, and solvents, namely methanol and heptane, while 4.5‐bilayered PAH‐PSS film displays partial layer decomposition against 1 M NaOCl. Additionally, it is found that the stability of Layer‐by‐Layer (LbL) films remains unaffected by the surface charge type, although variations in the adsorbed and desorbed amounts, as well as the viscoelastic properties, occur during the salt passage and rinsing steps. Along the salt exposure, changes in dissipation (ΔD) significantly increase because of the fast diffusion of ions through the multilayers but return to their initial value after washing. Especially high and reversible ΔD values of the PEMs against methanol are evaluated as swelling in methanol without chemical disintegration. This behavior can be attractive for solvent‐induced release behavior for the LbL‐assembled films or microcapsules.Highlights Multilayer stability and solvent swelling of PEMs are discussed using QCM‐D. PAH‐PSS films have the highest stability against salt solutions. PAH‐PAA films exhibited significant changes in dissipation values. PEMs did not show multilayer stability against NaOCl solution. (PAH‐PSS)5 film was stable and had swelling/de‐swelling capability against methanol.

Contamination of the Bushveld Complex (South Africa) magmas by basinal brines: Stable isotopes in phlogopite from the UG2 chromitite

Abstract There is abundant evidence for significant H2O in evolved melts from the platinum-rich UG2 chromitite and the Merensky Reef of the Bushveld Complex (South Africa), but there is no consensus about the source of H2O. We report triple-oxygen and hydrogen isotope ratios of interstitial, late-magmatic phlogopite from three localities of the UG2 layer. The phlogopite yielded δD values of −43 to −23, which is >30 higher than previously known from Bushveld rocks and far above the mantle values of ~−75. The phlogopite triple-oxygen isotope ratios are the first to be reported for Bushveld rocks, with values of Δ′17O0.5305 (17O excess relative to the reference line 0.5305) from –0.069 to –0.044 (δ18O 5.2–6.2). The oxygen data support existing models of as much as 30%–40% contamination of mantle-derived magmas in the lower to middle crust. However, the high δD values require a second step of contamination, which we attribute to brines from the marine sediments in the Transvaal Basin at the emplacement level.

Highly volatile element (H, C, F, Cl, S) abundances and H isotopic compositions in chondrules from carbonaceous and ordinary chondrites

The partial pressures and isotopic compositions of volatiles present during chondrule formation can be constrained by the highly volatile element or HVE (H, C, F, Cl, and S) abundances and isotopic compositions in chondrules. Here we present the results of high spatial resolution and low background secondary ion mass spectroscopy (SIMS) analyses of the HVE concentrations and H isotopic compositions in type I and II chondrules in primitive ordinary chondrites Semarkona (LL3.00) and Queen Alexandra Range (QUE) 97008 (L3.05), and the primitive carbonaceous chondrite Dominion Range (DOM) 08006 (CO3.00). The HVEs in the chondrules primarily reside in the mesostases, in which the HVE contents and H isotopic compositions vary significantly (H2O: 8–10,200 ppm, CO2: 2.4–1170 ppm, F: 0.3–30 ppm, Cl: 0.07–175 ppm, S: 0.38–4400 ppm, δD: 77–15,000‰). To dissolve such HVE contents in a silicate melt requires significantly higher total pressures (up to 1900 bars), and in some cases requires anomalous gas compositions (CO dominated), compared to those expected from canonical conditions of chondrule formation (∼10−3 bars, H2 + H2O dominated). Rather, the enrichments of H2O, CO2, Cl, and F in the mesostases at the edges of some chondrules suggest that there were secondary influxes of HVEs into the chondrule mesostases from the surrounding matrix during parent body processes. Consistent with this, melt inclusions sealed in olivine phenocrysts have significantly lower HVE contents than the mesostases in contact with the surrounding matrix material. Further, the calculated diffusion distances of H2O in silicate glasses under the relevant conditions are comparable to the radii of the chondrules. The high δD values in the mesostases could have been generated through isotopic Rayleigh fractionation as a result of the loss of very D-poor H2 generated from Fe metal oxidation by H2O in the parent bodies. Based on these results, we hypothesize that the bulk of the HVEs in the chondrules are secondary in origin. However, a small portion of the HVEs in chondrules could be primary, as there are low but measurable amounts of HVEs in the melt inclusions that are sealed in phenocrysts. Further, measured S contents in some chondrule mesostases agree with those predicted in a sulfide saturated silicate melt based on an experimentally calibrated thermodynamic model. We constrain the upper limits of primary HVEs in the chondrules based on the lowest measured HVE contents to minimize the effects of the secondary influx of HVEs (type I H2O: 7–11 ppm, CO2: 0.3–0.6 ppm, F: 0.1–0.2 ppm, Cl: 0.01–0.03 ppm, S: 0.3–60 ppm, and type II H2O: 50–85 ppm, CO2: 0.4–3 ppm, F: 0.04–2 ppm, Cl: 0.04–2 ppm, S: 190–260 ppm).

Methane with Abnormally High δ13C and δD Values from the Coastal Hot Springs in Lake Baikal

We studied the composition and isotopic characteristics (δ13C and δD) of hydrocarbon gases from the Kotelnikovsky, Zmeiny, and Goryachnisky hot springs located in the coastal zone of Lake Baikal. Of greatest interest is the Zmeiny Spring located on the eastern coast, where the methane has abnormally high values of δ13C (up to +11‰) and δD (up to +267‰). These values are related to the fractionation of carbon and hydrogen isotopes during the oxidation of microbial methane. The δ13C-C1 value (‒40.2‰) in the Goryachinsky Spring can formally indicate the thermogenic origin of methane. However, the modification of carbon isotope composition in this spring due to methane oxidation is more likely, because gas from the Goryachinsky Spring contains the microbial methane as admixture. Isotopic characteristics typical of microbial gases undistorted by secondary oxidation (δ13C-C1 = ‒61.5‰, δD-C1 = ‒230.2‰, δ13C-C2 = ‒56.6‰) are recorded in the Kotelnikovsky Spring northwest of Lake Baikal.

Formation of the Tocantinzinho 1989 Ma gold-only deposit (Pará State, northern Brazil), based on sulfur, oxygen, hydrogen, and carbon isotope data

The Tocantinzinho gold deposit in the Brazilian Amazon region, approximately 1989 Ma in age, contains 16.7 Mt of ore in syenogranite and monzogranite breccias and microbreccias, most with gold in pyrite, silicates and quartz, and a small part in quartz vein pyrites. Three hydrothermal phases are recognised, H1, H2, and H3, where H1, the first hydrothermal phase, is the oldest. The H1 transitional, late-magmatic hydrothermal phase altered feldspar to sericite and mafic minerals to chlorite. During the H2 hydrothermal phase, pyrite, gold, and minor galena were precipitated, followed by intense sericite alteration. The last hydrothermal phase, H3, was coeval with a large number of andesite intrusions that generated high-pressure fluid-driven cataclasis. This event opened veins, tension gashes, and pull aparts that were filled with carbonate, worm-like chlorite, prismatic quartz, galena, pyrite, and rutile, which likely displaced and concentrated the gold near the carbonate-filled structures.The minerals sulfide δ34S values vary between −4.4 and + 5.6‰, which is compatible with a sulfur magmatic source, and indicate that the sulfur and likely the gold are both magmatic. The δ18OSMOW values of carbonates vary between +7.63 and + 21.23‰ in a narrow range of δ13CPDB values between −3.94 and −1.69‰. Two explanations are possible for these values. If that the carbonate fluids were genetically related to the andesite magmatism, this fluid mixed with meteoric water, and degassing of this mixture occurred in the near-surface to produce dissolved inorganic CO2 with high δ18O value. Alternatively, when fluid mixing occurred, the oxidation state of the environment increased, and the δ13C values of the carbonates remained relatively uniform, whereas the δ34S values of the sulfides varied. The δ18O values of the quartz, sericite, and chlorite of the mineralized and barren rocks are consistent with δ18O values > +8 for the fluids that crystallized the chlorites and δ18O > + 4‰ for those that crystallized the muscovite. High δD values of these fluids, estimated from mineral δD values range between −2 and −25‰, and differentiate them from the fluids that form porphyry-type Cu–Au and orogenic deposits. The isotope data for Tocantinzinho present characteristics of an intrusion-related gold deposit that combines the features of equigranular, intrusion-hosted, mesozonal deposits, such as those hosted in reduced granite, with Au-rich porphyry deposits hosted in oxidized granites.

Moisture origin and stable isotope characteristics of precipitation in southeast Siberia

AbstractThe paper presents oxygen and hydrogen isotopes of 284 precipitation event samples systematically collected in Irkutsk, in the Baikal region (southeast Siberia), between June 2011 and April 2017. This is the first high‐resolution dataset of stable isotopes of precipitation from this poorly studied region of continental Asia, which has a high potential for isotope‐based palaeoclimate research. The dataset revealed distinct seasonal variations: relatively high δ18O (up to −4‰) and δD (up to −40‰) values characterize summer air masses, and lighter isotope composition (−41‰ for δ18O and −322‰ for δD) is characteristic of winter precipitation. Our results show that air temperature mainly affects the isotope composition of precipitation, and no significant correlations were obtained for precipitation amount and relative humidity. A new temperature dependence was established for weighted mean monthly precipitation: +0.50‰/°C (r2 = 0.83; p <.01; n = 55) for δ18O and +3.8‰/°C (r2 = 0.83, p < 0.01; n = 55) for δD. Secondary fractionation processes (e.g., contribution of recycled moisture) were identified mainly in summer from low d excess. Backward trajectories assessed with the Hybrid Single‐Particle Lagrangian Integrated Trajectory (HYSPLIT) model indicate that precipitation with the lowest mean δ18O and δD values reaches Irkutsk in winter related to moisture transport from the Arctic. Precipitation originating from the west/southwest with the heaviest mean isotope composition reaches Irkutsk in summer, thus representing moisture transport across Eurasia. Generally, moisture transport from the west, that is, the Atlantic Ocean predominates throughout the year. A comparison of our new isotope dataset with simulation results using the European Centre/Hamburg version 5 (ECHAM5)‐wiso climate model reveals a good agreement of variations in δ18O (r2 = 0.87; p <.01; n = 55) and air temperature (r2 = 0.99; p <.01; n = 71). However, the ECHAM5‐wiso model fails to capture observed variations in d excess (r2 = 0.14; p < 0.01; n = 55). This disagreement can be partly explained by a model deficit of capturing regional hydrological processes associated with secondary moisture supply in summer.

Meteoric fluid‐rock interaction in Variscan shear zones

AbstractVariscan shear zones in the Armorican Massif represent sites of strong fluid‐rock interaction. The hydrogen isotope composition of muscovite (δDMs) from syntectonic leucogranite allows to determine the source of fluids that infiltrated the footwall of three detachment zones and the South Armorican Shear Zone. Using temperatures of hydrogen isotope exchange estimated from microstructural data, we calculate the hydrogen isotope ratios of water (δDwater) present within the shear zones during high‐temperature deformation. A ~40‰ difference in δDwater values from deep to shallow crustal level reveals a mixing relationship between deep crustal fluids with higher δD values that range from −34 to −33‰, and meteoric fluids with δD values as low as −74‰ in the upper part of detachment footwalls.

Hydrogen isotopes in high 3He/4He submarine basalts: Primordial vs. recycled water and the veil of mantle enrichment

The hydrogen isotope value (δD) of water indigenous to the mantle is masked by the early degassing and recycling of surface water through Earth's history. High 3He/4He ratios in some ocean island basalts, however, provide a clear geochemical signature of deep, primordial mantle that has been isolated within the Earth's interior from melting, degassing, and convective mixing with the upper mantle. Hydrogen isotopes were measured in high 3He/4He submarine basalt glasses from the Southeast Indian Ridge (SEIR) at the Amsterdam–St. Paul (ASP) Plateau (δD = −51 to −90‰, 3He/4He = 7.6 to 14.1 RA) and in submarine glasses from Loihi seamount south of the island of Hawaii (δD = −70 to −90‰, 3He/4He = 22.5 to 27.8 RA). These results highlight two contrasting patterns of δD for high 3He/4He lavas: one trend toward high δD of approximately −50‰, and another converging at δD = −75‰. These same patterns are evident in a global compilation of previously reported δD and 3He/4He results. We suggest that the high δD values result from water recycled during subduction that is carried into the source region of mantle plumes at the core–mantle boundary where it is mixed with primordial mantle, resulting in high δD and moderately high 3He/4He. Conversely, lower δD values of −75‰, in basalts from Loihi seamount and also trace element depleted mid-ocean ridge basalts, imply a primordial Earth hydrogen isotopic value of −75‰ or lower. δD values down to −100‰ also occur in the most trace element-depleted mid-ocean ridge basalts, typically in association with 87Sr/86Sr ratios near 0.703. These lower δD values may be a result of multi-stage melting history of the upper mantle where minor D/H fractionation could be associated with hydrogen retention in nominally anhydrous residual minerals. Collectively, the predominance of δD around −75‰ in the majority of mid-ocean ridge basalts and in high 3He/4He Loihi basalts is consistent with an origin of water on Earth that was dominated by accretion of chondritic material.

Seasonal variation in stable isotope compositions of waters from a Himalayan river: Estimation of glacier melt contribution

AbstractStable isotopic compositions (δ18O and δD) in water samples collected from Parbati River in Himachal Pradesh, India, during 2002–2005 were measured to delineate the contributions from different sources in different seasons. A seasonal cycle with high δ18O and δD values (in ‰) during the spring (March to May; −9.2, −58.6), intermediate values during the winter (December to February; −10.1, −65.6), and low values during the south‐west monsoon (July to September; −10.9, −71.8) is observed. The d‐excess values (15.2 ± 2.1‰) are higher compared with the global meteoric waters indicating significant contribution (~26%) of moisture carried by western disturbances. Higher δ‐values during the spring are ascribed to enhanced contribution from snow melt. The lower δ‐values during the monsoon are due to various Rayleigh effects (altitude, continental, and amount effects) and large‐scale convection effect on rains. A three component‐mixing model using the isotopic data and some plausible end member isotopic values was applied to identify contributions to the river discharge from different sources such as groundwater or subsurface base flow, glacier/surface snow melt, and the monsoon rain. Meltwater from glacier and snow combines with the base flow in spring season. South‐west monsoon rain and glacier melt along with the base flow constitute the monsoon discharge. The post‐monsoon season and winter are dominated by groundwater contribution. About 80% of the discharge is contributed by glacier melts in spring season. In the rainy monsoon season, glacier/snow melt contributes ~41% of the discharge. The mean annual glacier melt contribution to the river water is estimated to be 44 ± 15%. The present estimate along with some previous studies suggest that glacier contribution to the river discharge increased from ~35% to 50% during the period 1990 to 2011. This is consistent with recent data on glacier retreats in the Himalayan region.

Holocene Precipitation Records from Inner Mongolia Derived from Hydrogen Isotope Compositions of Sediment Fatty Acids

ABSTRACTThe Inner Mongolian Plateau lies along the northern limit reached by the East Asian summer monsoon. This geographic setting makes it especially sensitive to environmental change and an excellent site for understanding Quaternary East Asian monsoon variability. In this study we present new results of hydrogen isotopic compositions of fatty acids extracted from sediments, which were used to construct Holocene paleoprecipitation (or moisture) changes in Northern China. The hydrogen isotopic composition (D/H ratio) of n-acids in the sedimentary sequence of the Duoerji peat, Inner Mongolia, was determined with gas chromatography and mass spectrometry. Changes in the precipitation from middle Inner Mongolia are recorded by the D/H ratio of n-C20, n-C22, n-C24, n-C26, n-C28 acids (δD). From 10–9 ka, the relatively high δD values indicate reduced precipitation in the Early Holocene. Subsequently, increased precipitation is reflected by reduced δD values from 9–5.5 ka. After 5.5 ka, gradually increasing δD values record an overall decrease in precipitation. The precipitation trends established for the Duoerji sequence are consistent with other major paleoclimate proxies in the East Asian monsoon region, especially with a distinct Holocene optimum of increased monsoonal activity from 9–5.5 ka. The δD resulting paleo-precipitation record clearly shows that the Holocene climate in Northern China is basically controlled by the insolation changes.

Hydrogen isotopic characteristic of hydrocarbon gas pyrolyzed by herbaceous swamp peat in hydrous and anhydrous thermal simulation experiments

In order to understand the influence of diagenetic water medium on hydrogen isotope of thermogenic coalbed gas, the hydrous and anhydrous pyrolytic simulation experiments have been carried out on herbaceous peat. We studied hydrogen isotope composition and its difference and evolution pattern of the pyrolysis hydrocarbon gases It was observed that diagenetic water medium exerts a significant influence on hydrogen isotopic composition of the pyrolysis hydrocarbon gases. The experiment added water with heavier hydrogen isotopic composition than peat-formed environmental water generated hydrocarbon gases with heavier hydrogen isotopic compositions. When peat was subject to continuous pyrolysis until 5.5%Ro, average δD values of the generated methane, ethane and propane were increased by 74‰, 42‰ and 66‰, respectively. It was considered that the reason for hydrous simulation experiment to increase hydrogen isotopic value of pyrolytic hydrocarbon gases is due to isotopic exchange between water-derived hydrogen and organic hydrogen. Mathematical models between the δD values of the hydrocarbon gases generated under the participation of freshwater with higher δD values and Ro values as well as between δD values of the generated hydrocarbon gases were established. These research results provide a scientific basis for the genetic study of thermogenic coalbed methane pyrolyzated by coal-forming materials formed in herbaceous marsh under the participation of diagenetic water media.

Impact-melt hygrometer for Mars: The case of shergottite Elephant Moraine (EETA) 79001

We report volatile concentrations and hydrogen isotope compositions of impact melts and minerals in EETA 79001. We observed chemical changes in pyroxene, maskelynite (or feldspathic glass), and merrillite in contact with or inside impact melts. All pyroxene grains analyzed here are inside or close to impact melt pockets and contain 10–41 ppm H2O and enriched in D (δD=+1729 to +3707‰), with the highest values found in a grain enclosed in an impact melt pocket. Maskelynite or feldspathic glass contains 6.3 to 98 ppm H2O with δD values of +1604 to +3938‰. The high H2O and δD values were obtained in those enclosed inside or in contact with the impact melts, whereas low H2O content (4 ppm) and terrestrial-like D/H value (δD of −90±82‰) were found in one maskelynite grain away from impact melts contains. Rims of ∼5 μm thickness of merrillite grains next to impact melts display Na-depletion by ∼0.9 wt%, and the sides in contact with impact melts show Mg-enrichment by ∼0.5 wt%. However, the H2O and δD values of merrillite interiors (39–242 ppm H2O and δD of +1682 to +3884‰) do not show correlation with their proximity to the impact melts. Rather, δD and 1/H2O of merrillite form a negative trend different from that of impact melt pockets and maskelynite, suggesting post-crystallization or late-crystallization interactions with the crustal fluids.The impact melt pockets in EETA 79001 contain 121–646 ppm H2O, 4.3–13 ppm F, 13–50 ppm Cl, 707–2702 ppm S, and the δD values of +3368 to +4639‰. The correlations between H2O, F, Cl, P2O5, and δD values of impact melts and feldspathic glass are consistent with mixing between a volatile-rich and high δD (+3000 to +5000‰) endmember and a volatile-poor and low δD endmember. The volatile-poor and low δD endmember is consistent with magmatic volatiles stored in silicates. The volatile-rich and high δD endmember represents pre-impact alteration materials by subsurface water. Alteration from the subsurface water, equilibrated with the present-day-like Martian atmosphere, occurred after the crystallization of the rock (∼170 Ma) and before impact launch (∼0.7 Ma). Our conclusion is different from the previous suggestion of an isotopically distinct subsurface water reservoir with a δD value of +1000 to +2000‰ in EETA 79001. Although heterogeneous subsurface water on Mars is possible, the previous study was likely biased by a limited number of analyses (n=2) and possible terrestrial contamination. The δD value of the subsurface source in EETA 79001 is ∼+4200‰, similar to those in the Tissint meteorite (crystallization at ∼600 Ma, impact launch at ∼0.7 Ma) and LAR 06319 (crystallization at ∼200 Ma, impact launch at ∼3 Ma), suggesting stable water chemistry for the subsurface environment in the last 600 Myrs.

Evolution of formation waters in the Permian Basin, United States: Late Permian evaporated seawater to Neogene meteoric water

Understanding subsurface waters is important for hydrocarbon exploration and development. Waters from the Permian Basin were collected and analyzed for stable isotopes, ionic concentrations, and strontium isotopes to determine their origin. Three main geochemical groups of waters are present. Group 1 has high δ18O and δD values with high total dissolved solids (TDS; 100–240 g/L), including high concentrations of Na+, Cl−, and Br−.Group 1 waters contain distinctly less sodium (Na+) than chlorine (Cl−) on a molar basis, similar to modern seawater. Group 2 and 3 waters have low δ18O and δD values. Group 2 waters have relatively low TDS (4–75 g/L). Group 3 waters have high TDS (170–225 g/L), Na+ and Cl− in approximately equal molar amounts, and low Br− concentrations. Group 1 waters are interpreted as forming from highly evaporated seawater during precipitation of uppermost Permian salts. Because of their high density, those waters displaced preexisting formation waters throughout the Permian Basin during the latest Permian. Waters in groups 2 and 3 came mainly from precipitation in the mountains of southeast New Mexico. Those mountains formed during Neogene tectonic uplifts. Group 3 waters acquired their Na+ and Cl− by dissolution of upper Permian salt. Many group 2 and 3 waters acquired their Ca2+ and SO42− by dissolution of Permian anhydrite or gypsum. Some waters contain a mixture of these groups. Understanding the origin of subsurface waters helps predict subsurface salinity, aquifer drive, sulfate reduction, chemical reactions during water injection, and chemistry of diagenetic waters.

Geochemical characteristics of water produced from CBM wells and implications for commingling CBM production: A case study of the Bide-Santang Basin, western Guizhou, China

Multi-layer commingling coalbed methane (CBM) development causes interlayer interference, which can severely impede the efficient pressure drop in CBM reservoirs and make it difficult to identify the produced water source. In this study, geochemical analyses (conventional ions, stable isotopes, and trace elements) were conducted on 38 water samples collected from 11 CBM wells, an adjacent river and the coal mine in the Bide-Santang Basin, western Guizhou, China. Variations in water quality caused by aquifer recharge, water-rock interactions, and the oxidation environment were revealed using principle component analysis and hierarchical cluster analysis. Li, Ga, Rb, Sr, and Ba were selected as characteristic trace elements, whose concentrations tend to increase with increasing producing layer depth. The water samples recorded an obvious D drift trend relative to the local meteoric water line (LMWL). Fracturing fluid from contaminated wells recorded elevated Cl− and Na+ concentrations and high δ18O and δD values. The geochemical parameters of d (the degree of D drift), δD, δ18O, Cl− + Na+ and characteristic trace element concentrations in produced water serve as indicators of the production and water source of CBM wells. Templates were created to discriminate between sources of produced water, including shallow groundwater, coal seam water, and fracturing fluid water. High-production wells are characterized by producing coal seam water, while low-production wells are characterized by producing shallow groundwater. The upper CBM system is susceptible to shallow groundwater recharge that involves multiple limestone aquifers, so it is recommended that the middle and lower CBM systems should be a priority for CBM development.

A decadal time series of water vapor and D / H isotope ratios above Zugspitze: transport patterns to central Europe

Abstract. We present vertical soundings (2005–2015) of tropospheric water vapor (H2O) and its D ∕ H isotope ratio (δD) derived from ground-based solar Fourier transform infrared (FTIR) measurements at Zugspitze (47° N, 11° E, 2964 m a.s.l.). Beside water vapor profiles with optimized vertical resolution (degrees of freedom for signal, DOFS, = 2.8), {H2O, δD} pairs with consistent vertical resolution (DOFS = 1.6 for H2O and δD) applied in this study. The integrated water vapor (IWV) trend of 2.4 [−5.8, 10.6] % decade−1 is statistically insignificant (95 % confidence interval). Under this caveat, the IWV trend estimate is conditionally consistent with the 2005–2015 temperature increase at Zugspitze (1.3 [0.5, 2.1] K decade−1), assuming constant relative humidity. Seasonal variations in free-tropospheric H2O and δD exhibit amplitudes of 140 and 50 % of the respective overall means. The minima (maxima) in January (July) are in agreement with changing sea surface temperature of the Atlantic Ocean. Using extensive backward-trajectory analysis, distinct moisture pathways are identified depending on observed δD levels: low column-based δD values (δDcol < 5th percentile) are associated with air masses originating at higher latitudes (62° N on average) and altitudes (6.5 km)than high δD values (δDcol > 95th percentile: 46° N, 4.6 km). Backward-trajectory classification indicates that {H2O, δD} observations are influenced by three long-range-transport patterns towards Zugspitze assessed in previous studies: (i) intercontinental transport from North America (TUS; source region: 25–45° N, 70–110° W, 0–2 km altitude), (ii) intercontinental transport from northern Africa (TNA; source region: 15–30° N, 15° W–35° E, 0–2 km altitude), and (iii) stratospheric air intrusions (STIs; source region: > 20° N, above zonal mean tropopause). The FTIR data exhibit significantly differing signatures in free-tropospheric {H2O, δD} pairs (5 km a.s.l.) – given as the mean with uncertainty of ±2 standard error (SE) – for TUS (VMRH2O = 2.4 [2.3, 2.6] × 103 ppmv, δD = −315 [−326, −303] ‰), TNA (2.8 [2.6, 2.9] × 103 ppmv, −251 [−257, −246] ‰), and STIs (1.2 [1.1, 1.3] × 103 ppmv, −384 [−397, −372] ‰). For TUS events, {H2O, δD} observations depend on surface temperature in the source region and the degree of dehydration having occurred during updraft in warm conveyor belts. During TNA events (dry convection of boundary layer air) relatively moist and weakly HDO-depleted air masses are imported. In contrast, STI events are associated with import of predominantly dry and HDO-depleted air masses. These long-range-transport patterns potentially involve the import of various trace constituents to the central European free troposphere, i.e., import of pollution from North America (e.g., aerosol, ozone, carbon monoxide), Saharan mineral dust, stratospheric ozone, and other airborne species such as pollen. Our results provide evidence that {H2O, δD} observations are a valuable proxy for the transport of such tracers. To validate this finding, we consult a database of transport events (TNA and STI) covering 2013–2015 deduced by data filtering from in situ measurements at Zugspitze and lidar profiles at nearby Garmisch. Indeed, the FTIR data related to these verified TNA events (27 days) exhibit characteristic fingerprints in IWV (5.5 [4.9, 6.1] mm) and δDcol (−266 [−284, −247] ‰), which are significantly distinguishable from the rest of the time series (4.3 [4.1, 4.5] mm, −316 [−324, −308] ‰). This holds true for 136 STI days considering uncertainties of ±1 SE (4.2 [4.0, 4.3] mm, −322 [−327, −316] ‰) with respect to the remainder (4.6 [4.5, 4.8] mm, −302 [−307, −297] ‰). Furthermore, deep stratospheric intrusions to the Zugspitze summit (in situ humidity and beryllium-7 data filtering) show a significantly lower mean value (−334 [−337, −330] ‰) of lower-tropospheric δD (3–5 km a.s.l.) than the rest of the 2005–2015 time series (−284 [−286, −282] ‰) considering uncertainty of ±2 SE. Our results show that consistent {H2O, δD} observations at Zugspitze can serve as an operational indicator for long-range-transport events potentially affecting regional climate and air quality, as well as human health in central Europe.

Stable isotope compositions of speleothems from the last interglacial – Spatial patterns of climate fluctuations in Europe

Studies on the last interglacial (LIG) can provide information on how our environment behaved in a period of slightly higher global temperatures at about 125 ± 4 ka, even if it is not the best analogue for the Holocene. The available LIG climate proxy records are usually better preserved and can be studied at a higher resolution than those of the preceding interglacials, allowing detailed comparisons. This paper presents complex stable hydrogen, carbon and oxygen isotope records obtained for carbonate (δ13C and δ18Ocarb) and fluid inclusion hosted water (δD and δ18Ow) of a stalagmite from the Baradla Cave system in Central Europe that covers most of the LIG, as proven by U-Th dates. Comparing its C and O isotope data with records reported for other speleothem (cave-hosted carbonate) deposits from Europe revealed the complex behavior of these climate proxies, with a concerted relative increase in 18O of carbonates from 128 to 120 ka and synchronized shifts in the opposite direction after 119 ka. The hydrogen isotope analyses of inclusion-hosted water extracted from the BAR-II stalagmite also correspond to the regional climate proxy records, with meaningful deviations from global temperature trends. Beside following the general paleotemperature pattern from the climate optimum (high δD values up to −64‰ around 120 ka) to the subsequent cooling starting at about 119 ka (low δD values down to −90‰ at about 109 ka), a period between 126.5 and 123 ka with low δD values (down to −81‰) is detected in the BAR-II stalagmite. Although the isotope shifts are muted in the C-O isotope data of carbonate due to competitive fractionation processes, the δ13C data show a positive relationship with the δD pattern, indicating humidity – and possibly temperature – variations. The periods with low δD values fit well to temperature and humidity changes inferred from proxy records from western Europe to the eastern Mediterranean. Spatial distributions of these variables show, that at about 125 ± 2 ka the Mediterranean region was characterized by warm, humid conditions and enhanced seasonality with elevated winter precipitation. The combined interpretation of stable isotope data revealed that the Alpine and Mediterranean regions behaved differently during Greenland Stadial 26 (GS26, ∼119 to 116.2 ka). While the Alpine records fluctuated in close agreement with the Central Greenland ice core δ18O data, the BAR-II stalagmite show a positive δ18Ocarb anomaly. The Baradla data indicate enhanced aridity and seasonality for a part of GS26, with the relative dominance of summer precipitation and Mediterranean moisture contribution. Following the GS26 event, the effect of long-term global cooling becomes dominant in the Baradla isotope records and leads to glacial inception at about 109 ka.