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Papers by Yuri Dublyansky

Environ Earth Sci, 1999

ABSTRACT

Egu General Assembly Conference Abstracts, May 1, 2010

Insights into the origin of secondary calcite at Yucca Mountain (Nevada) from high-resolution sta... more Insights into the origin of secondary calcite at Yucca Mountain (Nevada) from high-resolution stable isotope data coupled with fluid-inclusion microthermometry and deltaD analyses

Three major settings of hydrothermal karst development are: • Endokarst. • Deep-seated karst. • S... more Three major settings of hydrothermal karst development are: • Endokarst. • Deep-seated karst. • Shallow karst. Endokarst develops at great depth, where the pressure exceeds the strength of the rock. Voids can exist only if they are filled with overpressured fluid that prevents them from collapse. Deep-seated hydrothermal karst develops in response to changes of pressure and temperature of upwelling fluids. Shallow karst encompasses the interface between thermal and low-temperature water or the zone near the upper surface of thermal water. Two large zones form within hydrothermal systems • A zone of carbonate dissolution. • A zone of carbonate precipitation. Four major conditions create and enhance solutional capacity in hydrothermal systems • Elevated temperature gradients (for carbonated waters). • Elevated rate of discharge (for carbonated waters). • Oxidation of hydrogen sulfide. • Mixing waters of contrasting chemistry.

Condensation in karst occurs over a wide range of natural settings, at latitudes from 25º to 70º ... more Condensation in karst occurs over a wide range of natural settings, at latitudes from 25º to 70º and altitudes from sea level to 2600 m. In summer (April through September), condensation introduces a significant amount of water into the karst massifs (from 0.1% to as much as 20% of the total dry-season runoff). Contrary to common belief, in winter evaporation does not withdraw appreciable amounts of water from the massifs. Evaporating at depth, the water condenses near the surface within the epikarstic zone or on the snow cover and flows back. Condensation can sustain springs during prolonged dry periods (such as summer and winter) when there is no recharge by liquid precipitation.

Y. V. Dublyansky, C. E. Pashchenko Nuclear energy is SOR The role of nuclear energy in combating ... more Y. V. Dublyansky, C. E. Pashchenko Nuclear energy is SOR The role of nuclear energy in combating global climate chang Во время конференции СОР3 в декабре 1997 года в Киото обсуждался, хотя и вне рамок основной программы, вопрос о роли, которую должна играть атомная энергетика в снижении эмиссии парниковых газов.

A semi-empirical model is presented, which describes the processes of formation, migration, and a... more A semi-empirical model is presented, which describes the processes of formation, migration, and accumulation of radiogenic lead (PbRn) in opals deposited in open cavities. In contrast to lead that forms in situ through radioactive decay of uranium trapped by opal, PbRn is produced from uranium disseminated in the rock enclosing the cavities. Its incorporation into the opal is described by the following chain of processes: decay of parental uranium to yield radon -emanation and diffusion migration of radon from the rock into the cavity -decay of radon to yield lead -diffusion migration of lead in the cavityadsorption of lead on colloidal silica particles -coagulation and settling of the colloidal particles -formation of opal. Besides the colloidal adsorption, PbRn can also be incorporated into the growing opal through direct diffusion flow onto its surface. The latter mechanism is also relevant to minerals crystallizing from ionic solutions; it is less efficient than the mechanism of colloidal adsorption. Distribution of PbRn isotopes throughout a cavity depends on the cavity geometry and the half-life of the parental Rn isotope. In cavity filled with stagnant water, the concentration profiles of PbRn show maxima at some distance from the cavity wall. The movement of water through a cavity leads to a more complex distribution of PbRn isotopes. The model describes accumulation of PbRn on silica micelles during their growth until the critical size of coagulation (5-10 nm) is reached and during the subsequent coagulation. For micelles 5-50 nm in size, the calculated concentrations of PbRn agree with those in young (Miocene and younger) natural opals.

In July 1998 IEER commissioned Dr. Yuri Dublyansky of the Siberian Branch of the Russian Academy ... more In July 1998 IEER commissioned Dr. Yuri Dublyansky of the Siberian Branch of the Russian Academy of Sciences to prepare and study mineral samples that he collected in the previous month from the Yucca Mountain tunnel in Nevada. This five-mile tunnel has been drilled to study the suitability of the site for disposal of spent fuel from US nuclear power plants and highly radioactive waste from military plutonium production. Dr. Dublyansky is a geologist who specializes in fluid inclusions in minerals.

Analysis of the oxygen isotopic composition of fluid inclusion water in calcite has long been con... more Analysis of the oxygen isotopic composition of fluid inclusion water in calcite has long been considered not feasible (e.g., , because it was perceived that small amounts of water trapped inside calcite exchange its oxygen with the surrounding. This contention, however, has not been thoroughly tested.

Among the ever increasing number of caves visited and studied by paleoclimate scientists around t... more Among the ever increasing number of caves visited and studied by paleoclimate scientists around the globe one site is special for a number of reasons. First described in the literature in 1988, Devils Hole is a geometrically simple cave developed along an extensional fracture in the Amargosa Desert of SW Nevada. The deeper portion of this cavity is phreatic and part of a regional aquifer whose lowest discharge point is Death Valley. Landmark studies by Ike Winograd s team examined thick calcite crusts present on the walls of this and a neighboring cave (termed Devils Hole #2) and retrieved one of the most remarkable (and thought-provoking) isotope proxy records covering the last half million of years (1992). More recently, Coplen scrutinized the stable isotope systematics at Devils Hole. His results suggest that this setting represents a rare example of inorganic calcite precipitation essentially at isotopic equilibrium. We obtained permission from the Death Valley National Park Service to study and sample Devils Hole #2. While previous studies were based on samples from the phreatic zone we cored the calcite crust just above the groundwater table in an attempt to extend the original record further back in time and to obtain direct paleowater isotope data. Stable isotope data obtained along one core show a very high degree of similarity with the published DH11 core and a first set of U-series dates confirms the stratigraphy down to 476 ka. Older calcite also shows glacial-interglacial oscillations in both carbon and oxygen isotopes. A tentative correlation with Antarctic and deep-sea isotope records suggests that the lower part of the calcite is ca. 800 ka old (i.e. MIS 20). The cores show petrographic evidence of falling groundwater levels during MIS 9, 7 and 5e, but there are no indications of major hiati. Interestingly, growth at our drill location ended shortly after 20 ka BP, i.e. much later than at the subaqueous site in Devils Hole proper where DH11 was retrieved (ca. 60 ka BP). This observation is consistent with Winograd et al. (2006) who extended the original DH11 stratigraphy up to the mid-Holocene using additional samples drilled in the phreatic part of Devils Hole #2.

The Miocene rhyolitic tuffs comprising the thick vadose zone of Yucca Mountain host abundant frac... more The Miocene rhyolitic tuffs comprising the thick vadose zone of Yucca Mountain host abundant fracture-filling calcite, which has previously been studied to reconstruct the paleohydrogeology at the proposed high-level nuclear waste disposal site. The origin of calcite has been explained by deposition from infiltrating meteoric water (Whelan et al., 2002). Early isotopic studies of this calcite found that its δ 18 O values increase with depth below surface, which was interpreted as a reflection of the "normal" geothermal gradient (Szabo and Kyser, 1990). Subsequently, δ 18 O was found to increase from early to late stages of calcite growth; this was interpreted as indication of a temperature decrease. δ 13 C values showed a concomitant decrease attributed to the evolution of carbon sources from methanogenic bacteria to plants (with a gradually increasing contribution from C4-plants; Whelan et al., 2002).

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Researches performed during the last decade in the Crimean Piedmont have revealed widespread mani... more Researches performed during the last decade in the Crimean Piedmont have revealed widespread manifestations of relict hypogene karst which was developing since late Miocene till Middle Pleistocene in relatively confined hydrogeological settings by upwelling deep groundwaters flowing across the Cretaceous-Neogene homocline of the upper structural storey of the northern slope of the Crimean Mountains. Main pathways of cross-formational groundwater flows were sub-vertical disruptions (fractures), transformed by hypogene speleogenesis into large fracture-karstic conduits («rifts») ranging from a few centimetres to 2-3 metres in width. Interaction of ascending conduit flows with pore waters of the intersected carbonate strata of late Cretaceous, Paleocene and Eocene resulted in the formation of cavernous fringe (small cavernousity, solution pockets, stratiform niches and large chambers) and haloes of an altered rock.

Таврический национальный университет им. В.И.Вернадского Украинский Институт спелеологии и карсто... more Таврический национальный университет им. В.И.Вернадского Украинский Институт спелеологии и карстологии МОНМС Украины и НАН Украины Климчук А.Б. Тимохина Е.И. Амеличев Г.Н. Дублянский Ю.В. Шпетль К. ГИПОГЕННЫЙ КАРСТ ПРЕДГОРНОГО КРЫМА И ЕГО ГЕОМОРФОЛОГИЧЕСКАЯ РОЛЬ Симферополь "ДИАЙПИ" 2013 УДК [551.44+551.435.8] (477.75) ББК 26.823 К 49

Environ Earth Sci, 1999

ABSTRACT

Egu General Assembly Conference Abstracts, May 1, 2010

Insights into the origin of secondary calcite at Yucca Mountain (Nevada) from high-resolution sta... more Insights into the origin of secondary calcite at Yucca Mountain (Nevada) from high-resolution stable isotope data coupled with fluid-inclusion microthermometry and deltaD analyses

Three major settings of hydrothermal karst development are: • Endokarst. • Deep-seated karst. • S... more Three major settings of hydrothermal karst development are: • Endokarst. • Deep-seated karst. • Shallow karst. Endokarst develops at great depth, where the pressure exceeds the strength of the rock. Voids can exist only if they are filled with overpressured fluid that prevents them from collapse. Deep-seated hydrothermal karst develops in response to changes of pressure and temperature of upwelling fluids. Shallow karst encompasses the interface between thermal and low-temperature water or the zone near the upper surface of thermal water. Two large zones form within hydrothermal systems • A zone of carbonate dissolution. • A zone of carbonate precipitation. Four major conditions create and enhance solutional capacity in hydrothermal systems • Elevated temperature gradients (for carbonated waters). • Elevated rate of discharge (for carbonated waters). • Oxidation of hydrogen sulfide. • Mixing waters of contrasting chemistry.

Condensation in karst occurs over a wide range of natural settings, at latitudes from 25º to 70º ... more Condensation in karst occurs over a wide range of natural settings, at latitudes from 25º to 70º and altitudes from sea level to 2600 m. In summer (April through September), condensation introduces a significant amount of water into the karst massifs (from 0.1% to as much as 20% of the total dry-season runoff). Contrary to common belief, in winter evaporation does not withdraw appreciable amounts of water from the massifs. Evaporating at depth, the water condenses near the surface within the epikarstic zone or on the snow cover and flows back. Condensation can sustain springs during prolonged dry periods (such as summer and winter) when there is no recharge by liquid precipitation.

Y. V. Dublyansky, C. E. Pashchenko Nuclear energy is SOR The role of nuclear energy in combating ... more Y. V. Dublyansky, C. E. Pashchenko Nuclear energy is SOR The role of nuclear energy in combating global climate chang Во время конференции СОР3 в декабре 1997 года в Киото обсуждался, хотя и вне рамок основной программы, вопрос о роли, которую должна играть атомная энергетика в снижении эмиссии парниковых газов.

A semi-empirical model is presented, which describes the processes of formation, migration, and a... more A semi-empirical model is presented, which describes the processes of formation, migration, and accumulation of radiogenic lead (PbRn) in opals deposited in open cavities. In contrast to lead that forms in situ through radioactive decay of uranium trapped by opal, PbRn is produced from uranium disseminated in the rock enclosing the cavities. Its incorporation into the opal is described by the following chain of processes: decay of parental uranium to yield radon -emanation and diffusion migration of radon from the rock into the cavity -decay of radon to yield lead -diffusion migration of lead in the cavityadsorption of lead on colloidal silica particles -coagulation and settling of the colloidal particles -formation of opal. Besides the colloidal adsorption, PbRn can also be incorporated into the growing opal through direct diffusion flow onto its surface. The latter mechanism is also relevant to minerals crystallizing from ionic solutions; it is less efficient than the mechanism of colloidal adsorption. Distribution of PbRn isotopes throughout a cavity depends on the cavity geometry and the half-life of the parental Rn isotope. In cavity filled with stagnant water, the concentration profiles of PbRn show maxima at some distance from the cavity wall. The movement of water through a cavity leads to a more complex distribution of PbRn isotopes. The model describes accumulation of PbRn on silica micelles during their growth until the critical size of coagulation (5-10 nm) is reached and during the subsequent coagulation. For micelles 5-50 nm in size, the calculated concentrations of PbRn agree with those in young (Miocene and younger) natural opals.

In July 1998 IEER commissioned Dr. Yuri Dublyansky of the Siberian Branch of the Russian Academy ... more In July 1998 IEER commissioned Dr. Yuri Dublyansky of the Siberian Branch of the Russian Academy of Sciences to prepare and study mineral samples that he collected in the previous month from the Yucca Mountain tunnel in Nevada. This five-mile tunnel has been drilled to study the suitability of the site for disposal of spent fuel from US nuclear power plants and highly radioactive waste from military plutonium production. Dr. Dublyansky is a geologist who specializes in fluid inclusions in minerals.

Analysis of the oxygen isotopic composition of fluid inclusion water in calcite has long been con... more Analysis of the oxygen isotopic composition of fluid inclusion water in calcite has long been considered not feasible (e.g., , because it was perceived that small amounts of water trapped inside calcite exchange its oxygen with the surrounding. This contention, however, has not been thoroughly tested.

Among the ever increasing number of caves visited and studied by paleoclimate scientists around t... more Among the ever increasing number of caves visited and studied by paleoclimate scientists around the globe one site is special for a number of reasons. First described in the literature in 1988, Devils Hole is a geometrically simple cave developed along an extensional fracture in the Amargosa Desert of SW Nevada. The deeper portion of this cavity is phreatic and part of a regional aquifer whose lowest discharge point is Death Valley. Landmark studies by Ike Winograd s team examined thick calcite crusts present on the walls of this and a neighboring cave (termed Devils Hole #2) and retrieved one of the most remarkable (and thought-provoking) isotope proxy records covering the last half million of years (1992). More recently, Coplen scrutinized the stable isotope systematics at Devils Hole. His results suggest that this setting represents a rare example of inorganic calcite precipitation essentially at isotopic equilibrium. We obtained permission from the Death Valley National Park Service to study and sample Devils Hole #2. While previous studies were based on samples from the phreatic zone we cored the calcite crust just above the groundwater table in an attempt to extend the original record further back in time and to obtain direct paleowater isotope data. Stable isotope data obtained along one core show a very high degree of similarity with the published DH11 core and a first set of U-series dates confirms the stratigraphy down to 476 ka. Older calcite also shows glacial-interglacial oscillations in both carbon and oxygen isotopes. A tentative correlation with Antarctic and deep-sea isotope records suggests that the lower part of the calcite is ca. 800 ka old (i.e. MIS 20). The cores show petrographic evidence of falling groundwater levels during MIS 9, 7 and 5e, but there are no indications of major hiati. Interestingly, growth at our drill location ended shortly after 20 ka BP, i.e. much later than at the subaqueous site in Devils Hole proper where DH11 was retrieved (ca. 60 ka BP). This observation is consistent with Winograd et al. (2006) who extended the original DH11 stratigraphy up to the mid-Holocene using additional samples drilled in the phreatic part of Devils Hole #2.

The Miocene rhyolitic tuffs comprising the thick vadose zone of Yucca Mountain host abundant frac... more The Miocene rhyolitic tuffs comprising the thick vadose zone of Yucca Mountain host abundant fracture-filling calcite, which has previously been studied to reconstruct the paleohydrogeology at the proposed high-level nuclear waste disposal site. The origin of calcite has been explained by deposition from infiltrating meteoric water (Whelan et al., 2002). Early isotopic studies of this calcite found that its δ 18 O values increase with depth below surface, which was interpreted as a reflection of the "normal" geothermal gradient (Szabo and Kyser, 1990). Subsequently, δ 18 O was found to increase from early to late stages of calcite growth; this was interpreted as indication of a temperature decrease. δ 13 C values showed a concomitant decrease attributed to the evolution of carbon sources from methanogenic bacteria to plants (with a gradually increasing contribution from C4-plants; Whelan et al., 2002).

[

Researches performed during the last decade in the Crimean Piedmont have revealed widespread mani... more Researches performed during the last decade in the Crimean Piedmont have revealed widespread manifestations of relict hypogene karst which was developing since late Miocene till Middle Pleistocene in relatively confined hydrogeological settings by upwelling deep groundwaters flowing across the Cretaceous-Neogene homocline of the upper structural storey of the northern slope of the Crimean Mountains. Main pathways of cross-formational groundwater flows were sub-vertical disruptions (fractures), transformed by hypogene speleogenesis into large fracture-karstic conduits («rifts») ranging from a few centimetres to 2-3 metres in width. Interaction of ascending conduit flows with pore waters of the intersected carbonate strata of late Cretaceous, Paleocene and Eocene resulted in the formation of cavernous fringe (small cavernousity, solution pockets, stratiform niches and large chambers) and haloes of an altered rock.

Таврический национальный университет им. В.И.Вернадского Украинский Институт спелеологии и карсто... more Таврический национальный университет им. В.И.Вернадского Украинский Институт спелеологии и карстологии МОНМС Украины и НАН Украины Климчук А.Б. Тимохина Е.И. Амеличев Г.Н. Дублянский Ю.В. Шпетль К. ГИПОГЕННЫЙ КАРСТ ПРЕДГОРНОГО КРЫМА И ЕГО ГЕОМОРФОЛОГИЧЕСКАЯ РОЛЬ Симферополь "ДИАЙПИ" 2013 УДК [551.44+551.435.8] (477.75) ББК 26.823 К 49

The formation of speleothems in the cave is a complex geochemical process dependent on various hy... more The formation of speleothems in the cave is a complex geochemical process dependent on various hydrological and environmental conditions. Using stable isotopes as a paleoclimate proxy is a challenge due to the multitude of fractionation processes. It is of utmost importance to understand and possibly quantify mechanisms in the cave that are influencing speleothem precipitation. The environmental process that is considered to be crucial for the equilibrium carbonate precipitation is the spatial and temporal variability of CO 2. To better characterize cave ventilation patterns, monitoring of pCO 2 , δ 13 C and δ 18 O in cave air at high temporal resolution (up to 1 s) was performed in Spannagel Cave, a high-alpine cave system in the Zillertal Alps, Austria. A Thermo Scientific Delta Ray Isotope Ratio Infrared Spectrometer was installed in a chamber ca. 100 m behind the cave entrance. The air temperature was independently monitored inside and outside the cave. The data show two distinct patterns in terms of CO 2 concentration and its isotopic composition, which are closely coupled with the temperature difference between the cave interior and the outside atmosphere. This gradient controls the direction of air flow in the cave on a seasonal to synoptic timescale (chimney-type ventilation). The summer circulation is characterized by CO 2 closely resembling atmospheric values (pCO 2 = 399 ± 12 ppm, δ 13 C =-8.5 ± 0.7‰, δ 18 O = 8.1 ± 2.5 ‰). The winter circulation mode features generally higher CO 2 concentrations and lower isotopic compositions (pCO 2 = 409 ± 14 ppm, δ 13 C =-10.1 ± 0.7 ‰, δ 18 O = 2.3 ± 1.5 ‰). The high temporal resolution of stable isotope data allows tracking cave air ventilation changes, including transient and short-lived ones. Specifically, periods impacted by respiration from cave visitors were filtered based on a linear mixing model.