The first data on helium isotopy in a transitional clay layer at the cretaceous-paleogene boundary (Gams,Eastern Alps)     

A. F. Grachev  I. L. Kamensky  O. A. Korchagin  H. A. Kollmann 《Izvestiya Physics of the Solid Earth》2007,43(9):766-772

The paper presents preliminary results derived from the study of He isotopy in a transitional clay bed at the critical 65-Ma boundary in the Gams area (Eastern Alps). The ratio ³He/⁴He is shown to decrease from bottom to top of the transitional layer, and the difference between its values in the lower-and uppermost sublayers of the layer exceeds by more than ten times the measurement uncertainty (5%). The ratio ³He/⁴He is smallest in the upper part of the section, where all features of an impact event (spherules of pure nickel, diamonds, and awaruite) are established. The general inference of our study is that ³He enrichment in the lower part of the Gams section is related not to cosmic matter but to a change in the conditions in the source area, most likely, to volcanic activity. The effect of the latter has been established, independent of He isotopic studies, from anomalous concentrations of As, Pb, Cu, and Zn and from the presence of particles of gold, copper, and titanomagnetite similar in composition to its basaltic varieties.  相似文献   

Determining the genesis of decrepitating and nondecrepitating microinclusions in minerals by the investigation of helium and argon isotopes     

I. L. Kamensky  V. I. Skiba 《Geochemistry International》2011,49(1):46-54

Previously published data were analyzed on the isotopic systematics of noble gases extracted from samples using various methods. By the example of four minerals from the rocks of the Kola Peninsula, it was shown that a comparison of the results provides the most comprehensive and reliable information on the qualitative and quantitative composition of gases and allows discrimination between fluid microinclusions of different origin (primary and secondary).  相似文献   

Isotope-Geochemical Features and Genesis of Gases in the East Carpathian Region     

B. G. Polyak  A. L. Cheshko  O. E. Kikvadze  I. L. Kamensky  E. M. Prasolov 《Lithology and Mineral Resources》2018,53(5):380-393

The paper presents data on the composition of a gas phase of underground fluids in the East Carpathian region, including ³He/⁴He, ⁴⁰Ar/³⁶Ar, and ⁴He/²⁰Ne ratios. The argon isotope composition of these gases was used to estimate the fractions of atmospheric Aratm and radiogenic ⁴⁰Ar_rad formed in the rocks, N₂/Aratm ratio, and to reveal the admixture of nonatmogenic (“excess”) nitrogen in most samples. The CO₂ content in gases positively correlates with the fraction of mantle component in fluid helium. At the same time, the CO₂ content shows a negative correlation with the total helium (and light ³He enriching mantle derivatives), thus excluding the simultaneous influx of CO₂ and helium from a common mantle source in the fluids. A wide spectrum of ³He/⁴He = R in gases of the region spanning three orders of magnitude confirms the concept of mixing of the crustal and mantle components in the helium. However, even gases with similar R values show a wide scatter of He concentrations. This is mainly caused by the additional influx of other gases: CH₄ formed during OM transformation or CO₂ released during the thermal metamorphism of carbonate sequences. Correlation of the CH₄/³He ratio and the helium isotope composition in the Carpathian gases indicates the crustal origin of hydrocarbons, which formed economic gas pools in the Ciscarpathian Trough and the adjacent part of the Folded Carpathians. Lateral chemical and isotope variations revealed in the underground fluids are related to the tectonic zoning of the region. The helium isotope variations are also consistent with the geodynamic setting of the region (thinning of the crust and lithosphere towards the Pannonian Basin, growth of the background conductive heat flow and corresponding ascent of isotherms). In combination with geothermal data, they reflect specifics of the mantle heat-and-mass flow discharge.  相似文献   

Origin,Occurrence, and Mobility of He and Ar Isotopes in Meliphanite     

Lyalina  L. M.  Kamensky  I. L.  Tolstikhin  I. D. 《Doklady Earth Sciences》2019,488(1):1120-1122

Doklady Earth Sciences - The U, Th, and 4He contents of meliphanite correspond to an age of metamorphism (1800 Ma) indicating good preservation of radiogenic 4He in mineral but contradicting the...  相似文献   

Conditions of the formation of thermomineral waters in the Talysh fold zone of the Lesser Caucasus (Azerbaijan) based on isotope-geochemical data (3Не/4Не, $${\delta ^{13}}{C_{c{o_2}}},{\delta ^{13}}{C_{c{h_4}}},{\delta ^{15}}{N_{{N_2}}}{,^{87}}Sr{/^{86}}Sr,\delta {D_{{H_2}O}},and{\delta ^{18}}{O_{{H_2}O}}$$)     

V. Yu. Lavrushin  Yu. G. Israfailov  B. G. Polyak  B. G. Pokrovsky  M. I. Bujakaite  I. L. Kamensky 《Lithology and Mineral Resources》2018,53(1):53-75

It is shown that the gas and water phases of the thermal nitrogen–methane waters in the Talysh fold zone of the Lesser Caucasus mountain system contain helium and strontium with mantle isotope signatures (³Не/⁴Не from 200 × 10^–8 to 401 × 10^–8 and ⁸⁷Sr/⁸⁶Sr from 0.70490 to 0.70562). At the same time, clear signs of the mantle component in other gases (nitrogen, methane, and carbon dioxide) are absent. The δ¹⁵N value in nitrogen varies from +0.3 to +1.7‰, methane is mainly characterized by δ¹³C from–57.4 to–38.0‰, while δ¹³C(CО₂) varies from–24.4 to–11.3‰. An increase of the CО₂ content is accompanied by the decrease of δ¹³C in CО₂, against the background of increasing SO₄ content in the salt composition of waters. This indicates a microbial nature of CO₂ in the studied gases. Thus, the presence of mantle helium and strontium in the thermal waters is likely related to their leaching from the Pleogene–Neogene host volcanic rocks. The studies of the oxygen and hydrogen isotope composition in water revealed quite different mechanisms for the formation of cold and thermal waters of the region. The cold waters are mainly fed by local infiltration, whereas the feeding of thermal nitrogen–methane waters is strongly provided by transit atmogenic waters (>50%), which are formed in the mountain ranges at altitudes no less than 1600 m and spaced at 20–40 km or more from the thermal discharge sites.  相似文献   

The tritium-helium-3 method and its application to groundwater dating by the example of the Kirovsk mine region,Murmansk oblast     

A. V. Gudkov  I. L. Kamensky  G. S. Melikhova  V. I. Skiba  I. V. Tokarev  I. N. Tolstikhin 《Geochemistry International》2014,52(7):587-594

The measurement of ³H, ³He, ⁴He, and ²⁰Ne concentrations in waters at the Tsentralny pumping station (southern Khibiny massif, Kola Peninsula) showed that they are a mixture of young (>90%) and old (<10%) waters. The excess noble gas component from the young water is caused by the dissolution of air bubbles trapped during recharge in the unsaturated zone. The ³H-³He(³H) age of the young water is 21 ± 1.5 yr. The U-Th-4He age of the old water is about 50 ka. The high concentrations of helium and some toxic elements (e.g., aluminum) in this old water are caused by dissolution of the alkaline rocks of the Khibiny massif as a result of water-rock interaction.  相似文献   

Recent tectonomagmatic reactivation of the Kolyuchino-Mechigmen zone of the Chukchi Peninsula from data on the composition of gases in hydrothermal springs     

B. G. Polyak  V. Yu. Lavrushin  A. L. Cheshko  E. M. Prasolov  I. L. Kamensky 《Geotectonics》2010,44(6):529-540

Thirty-three groups of thermal mineral springs in the Chukchi Peninsula are studied. The thermal fluids of the Kolyuchino-Mechigmen Zone (KMZ) show specific characteristics. The zone corresponds to recent depression with occurrences of basic volcanism and high seismicity. Characteristic features of the gases in the springs of the KMZ include the predominance of carbon dioxide, high percentage of mantle-derived helium, enrichment of CO₂ in ¹³C, admixture of nonatmospheric nitrogen, excess in ⁴⁰Ar and ¹⁵N relative to the atmosphere, maximal depletion of thermal water in deuterium and heavy oxygen isotope, and the highest estimates of deep temperature in reservoirs of hydrothermal fluid. All these features indicate the contemporary ascent of a mantle diapir that supplied helium enriched in ³He and thermal energy to the crust, thus provoking thermal metamorphism of rocks and degradation of permafrost.  相似文献   

Noble gas isotope sites and mobility in mafic rocks and olivine     

I. Tolstikhin  I. Kamensky  J. Kramers  V. Skiba  D. Novikov 《Geochimica et cosmochimica acta》2010,74(4):1436-6741

Important He and Ar isotope studies on rocks and minerals, relevant to the geochemical and degassing history of the Earth, are often hampered by insufficient knowledge of the retentivity of different types of sites in minerals (inclusions, matrix) for these species, and of the relative importance of radiogenic and trapped components and possible differences in their behavior.To identify sites of noble gas isotopes, shed some light on their origin and estimate their residence times in olivine, which is a mineral considered as a good natural sampler, we investigated 2.5 Ga old ultramafic rocks from the Monche Pluton (Kola Peninsula, north-east part of the Baltic shield) using several extraction methods: crushing, fusion, slow step-wise and rapid incremental heating. Previous studies indicated that these rocks contain mainly trapped noble gases; however, to constrain the possible contribution of in-situ generated radiogenic helium, U and Th concentrations were also measured in the samples.The helium release pattern obtained by relatively fast (∼1.5 h long) incremental heating of olivine includes three distinct release peaks for helium: a low-temperature (600 °C) l-peak, a middle (800-1100 °C) m-peak and a high-temperature (∼1400 °C) h-peak. However, helium extraction from a powdered aliquot of the same olivine yields mainly the middle m-peak indicating that gases released in the l- and h-peaks occupy gas-liquid inclusions opened in the course of crushing and grinding. Moreover, slow step-wise heating (14 h) also results in a broad He release peak but in two well-separated l- and h-peaks of non-atmospheric ⁴⁰Ar∗. This feature implies helium migration from l- and h-vesicles into the matrix m during long step-wise heating experiments, whereas less movable Ar remains in inclusions at even relatively high almost-magmatic temperatures.Using a simple phenomenological model envisaging the three different residence sites for noble gases, both fast- and slow-heating release patterns for ⁴⁰Ar∗ and He, including those for the crushed sample, could be reproduced. The diffusion parameters inferred from the modeling of olivine (D₀ = 2.4 × 10⁻² cm² s⁻¹ and Ea = 133 kJ mol⁻¹) are similar to those published by Shuster et al. (2003) and Blard et al. (2008). The high matrix/fluid solubility coefficient for helium, H_He ∼ 0.01, exceeds estimates reported by Trull and Kurz (1993); however, the product D_He(T) × H_He, the “permeability” (that governs He migration in vesicles + matrix composed materials), is very similar to their value. Extrapolation to the ambient temperature (0 °C) gives long and similar helium residence times in l- and h-vesicles, exceeding 10¹⁰ yrs, and even longer time scales ∼10¹⁶ yrs are obtained for the helium residence in the matrix. Therefore, at low temperatures our samples may be considered as excellent samplers of trapped volatile species, including helium.  相似文献