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Nadav G Lensky - One of the best experts on this subject based on the ideXlab platform.
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temperature seasonality control on modern Halite layers in the dead sea in situ observations
Geological Society of America Bulletin, 2017Co-Authors: Ido Sirota, Yehouda Enzel, Nadav G LenskyAbstract:Layered Halite sequences are found in deep basins throughout the geological record. However, analogs for such sequences are commonly studied in shallow environments. Here, we studied active precipitation of Halite layers from the only modern analog for deep, Halite-precipitating basins, the hypersaline Dead Sea. In situ observations in the Dead Sea link seasonal thermohaline stratification, Halite saturation, and the characteristics of the actively forming Halite layers. The spatiotemporal evolution of Halite precipitation in the Dead Sea was characterized by means of monthly observations of (1) lake thermohaline stratification (temperature, salinity, and density), (2) degree of Halite saturation, and (3) textural evolution of the active Halite deposits. We present the observed relationships between the textural characteristics of layered Halite deposits (i.e., grain size, consolidation, and roughness) and the degree of saturation, which in turn reflects the limnology and hydroclimatology. The lake floor is divided into two principal environments: a deep, hypolimnetic lake floor and a shallow, epilimnetic lake floor. In the deeper hypolimnetic lake floor, Halite continuously precipitates with seasonal variations: (1) During summer, consolidated coarse Halite crystals form rough surfaces under slight supersaturation. (2) During winter, unconsolidated, fine Halite crystals form smooth lake floor deposits under high supersaturation. These observations support interpretations of the seasonal alternation of Halite crystallization mechanisms. The shallow epilimnetic lake floor is highly influenced by the seasonal temperature variations, and by intensive summer dissolution of part of the previous year’s Halite deposit, which results in thin sequences with annual unconformities. This emphasizes the control of temperature seasonality on the characteristics of the precipitated Halite layers. In addition, precipitation of Halite on the hypolimnetic floor, at the expense of the dissolution of the epilimnetic floor, results in lateral focusing and thickening of Halite deposits in the deeper part of the basin and thinning of the deposits in shallow marginal basins.
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seasonal variations of Halite saturation in the dead sea
Water Resources Research, 2016Co-Authors: Ido Sirota, Ali Arnon, Nadav G LenskyAbstract:Hypersaline lakes and seas were common in the past, precipitating thick evaporitic salt deposits. The only modern analogue for the paleo-limnology of deep salt-saturated aquatic environments exists in the Dead Sea. In this study we present new insights from the Dead Sea on the role of seasonal thermohaline stratification and water balance on the seasonal and depth variations of the degree of saturation of Halite (salt) and the rate of Halite growth along the water column. We developed methodologies to accurately determine the empirical degree of Halite saturation of the lake based on high accuracy densitometry, and to quantify Halite growth rate along the water column. During summer, the epilimnion is undersaturated and Halite is dissolved, whereas during winter the entire water column is supersaturated and crystallizes Halite. This result is not trivial because the variations in the water balance suggest the opposite; summer is associated with higher loss of water by evaporation from the lake compared to the winter. Hence, the thermal effect overcomes the hydrological balance effect and thus governs the seasonal saturation cycle. The hypolimnion is supersaturated with respect to Halite and crystallizes throughout the year, with higher super saturation and higher crystallization rates during winter. During summer, simultaneous opposing environments coexist – an under-saturated epilimnion that dissolves Halite and a supersaturated hypolimnion that crystallizes Halite, which results in focusing of Halite deposits in the deep hypolimnetic parts of the evaporitic basins and thinning the shallow epilimnetic deposits. This article is protected by copyright. All rights reserved.
Fanwei Meng - One of the best experts on this subject based on the ideXlab platform.
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reconstruction of late cretaceous coastal paleotemperature from Halite deposits of the late cretaceous nongbok formation khorat plateau laos
Palaeoworld, 2016Co-Authors: Xiying Zhang, Fanwei Meng, Wenxia Li, Qiliang Tang, Pei NiAbstract:Abstract Cretaceous evaporites of the Maha Sarakhan Formation in Thailand (e.g., the Nongbok Formation, Laos) have been studied for almost a century as the huge potash deposits in the world. The consistently high local paleotemperatures should lead to huge salt deposits during the evaporation process. Primary fluid inclusions in Halite can provide surface brine water temperatures directly and quantitatively. Until now, there have been no data published from paleotemperature of primary fluid inclusions of Cretaceous Halite. The non-marine Halite from the Cretaceous Nongbok Formation (Laos) precipitated from shallow brine waters with temperatures of 17.7–42.3 °C.
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a newly isolated haloalkaliphilic bacterium from middle late eocene Halite formed in salt lakes in china
Carbonates and Evaporites, 2015Co-Authors: Fanwei Meng, Pei Ni, Chunhe Yang, Yinping Li, Xiuqiang Wang, Gunther Kletetschka, Yonghua YangAbstract:Ancient living halotolerant bacteria and ancient DNA have been reported from bedded marine Halite, but seldom from lacustrine Halite of the geological age. A halotolerant bacterium (Haloalkaliphilic bacterium, designated as 3-4) was isolated from primary Halite with abundant fluid inclusions. Primary Halite crystallized in lacustrine Yunying Depression located in the northeastern Jianghan Basin of central China. Yunying Depression is an inland salt paleolake residing in a faulted basin formed during late Cretaceous/early Tertiary. Brine inclusions from the same layer of the salt that housed Haloalkaliphilic bacterium 3-4 are the middle–late Eocene primary Halite crystals and have homogenization temperatures between 5.8 and 43.3 °C. The estimated age is between 33.9 and 48.6 Ma years old for these fluid inclusions, and this represents the long-term survivability of this microorganism Haloalkaliphilic bacterium 3-4. Sequence analysis of the partial fragment of 16S ribosomal DNA showed that the organism is similar to the lineage of Haloalkaliphilic bacterium and Oceanobacillus sp. The isolation of the microbe reinforces the long-term preservation possibility of life in extreme environment such as the fluid inclusions in Halite.
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the major composition of a middle late eocene salt lake in the yunying depression of jianghan basin of middle china based on analyses of fluid inclusions in Halite
Journal of Asian Earth Sciences, 2014Co-Authors: Fanwei Meng, A R Galamay, Pei Ni, Chunhe Yang, Yinping Li, Qingong ZhuoAbstract:Abstract During the Cretaceous–Tertiary transition in eastern China, abundant Halites formed in non-marine areas. Many continental salt deposits from inland salt lakes were formed in eastern China in faulted basins as a result of the northward movement and collision of the Indo-China Plate with the Eurasian Plate, including the Bohai Gulf Basin. However, a marine transgression versus a non-marine origin of these evaporites remains to be determined. Primary fluid inclusions trapped in Halite deposits can directly record the composition of evaporated seawater or salt lake water, such as those in the Cretaceous Halite in the Khorat Plateau (Laos and Thailand) area can resolve the origins of the evaporate deposits; recent fluid inclusions data in the Khorat Plateau coincide with the predicted secular variation of seawater and are comparable to other fluid inclusions in Cretaceous marine Halite, indicating these fluid inclusions are directly related to a marine transgression. Our analyses in this study shows that the average K+, Mg2+, and SO 4 2 - contents are 8.8, 5.0, and 6.8 g/l, respectively, in the primary fluid inclusions in Halite of middle–late Eocene from the Yunying depression of China. These numbers are much less than those in the contemporary Spanish primary fluid inclusions in Halite precipitated from seawater (16.4, 36.3, and 12.5 g/l for K+, Mg2+, and SO 4 2 - , respectively). Furthermore, Br contents of all fluid inclusion samples in Halite from the Yunying depression are lower than 2 ppm (vs. 55–58 ppm at the base of Spanish contemporary marine Halite), and their δ37Cl values range from −0.11‰ to +2.94‰ (vs. −0.09‰ to −0.24‰ in sylvite of Spanish deposit), indicating that the compositions of the middle–late Eocene brines trapped in Halite in the Yunying depression of China are very different from those derived from the contemporary seawater, and are considered to be resulted from evaporation of an inland saline lake water with little influence of seawater.
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ediacaran seawater temperature evidence from inclusions of sinian Halite
Precambrian Research, 2011Co-Authors: Fanwei Meng, Pei Ni, James D Schiffbauer, Xunlai Yuan, Chuanming Zhou, Yigang WangAbstract:Abstract Seawater temperatures throughout Earth's history have been suggested to illustrate a long-term cooling trend from nearly 70 °C at ∼3500 Ma to around 20 °C at ∼800 Ma. The terminal Neoproterozoic prior to the “Cambrian Explosion” is a key interval in evolutionary history, as complex multicellularity appeared with the advent of the Ediacara fauna. These organisms were likely the first that required higher levels of atmospheric and dissolved marine oxygen for their sustainability. It is known that most modern macroinvertebrates are intolerant of temperatures in excess of 45 °C. Perhaps more importantly, these high seawater temperatures limit the potential of dissolved oxygen, and therefore become an integral part of this evolutionary story. Previously, our understanding of seawater temperature during the terminal Neoproterozoic comes only from 18 O/ 16 O and 30 Si/ 28 Si ratios ascertained from a limited number of cherts. Isotopic ratio methods for assessing seawater temperatures are inherently indirect and have a wide range of oscillation. However, maximum homogenization temperatures (Th max ) of primary fluid inclusions in Halite provide a direct means of assessing brine temperature, and have been shown to correlate well with average maximum air temperatures. The oldest Halites date to the Neoproterozoic–lower Paleozoic (∼700–500 Ma), and Ediacaran representatives can be found in Sichuan Province, China, which do preserve primary fluid inclusions for analysis via cooling nucleation methods. We utilized Halite samples from the Changning-2 well, correlative to the Dengying Formation (551–542 Ma), to provide a direct assessment of terminal Neoproterozoic seawater temperature. Our measurements indicate that seawater temperatures where these Halites formed are highly similar to tropical Phanerozoic seawater temperature estimates. From compiled paleotemperature data, the decline in seawater temperatures over the course of the Proterozoic, accompanied by the reduction of seawater salinity with the sequestration of salt in massive Halite deposits in the Neoproterozoic, allowed the ocean system to accumulate more dissolved oxygen, and potentially paved the way for the evolutionary innovation of complex multicellularity.
Michael N Timofeeff - One of the best experts on this subject based on the ideXlab platform.
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how do prokaryotes survive in fluid inclusions in Halite for 30 k y
Geology, 2009Co-Authors: Brian A Schubert, Michael N Timofeeff, Tim K Lowenstein, Matthew A ParkerAbstract:Long-term survival of microorganisms has been demonstrated by prokaryotes cultured from ancient Halite, but previous results are controversial. Three genera of non-spore-forming halophilic Archaea were cultured from 22–34 k.y. old subsurface Halite from Death Valley, California. Primary, brine-filled inclusions in this Halite contained prokaryotic organisms in miniaturized starvation-survival forms and dead cells of the algal genus Dunaliella . The energy needed for protracted survival of halophilic Archaea , including repair of damaged DNA, may have been provided by glycerol and other carbon molecules leaked from Dunaliella cells. These results provide further evidence that fluid inclusions in Halite are a favorable refuge for long-term survival of microorganisms, and indicate that the original depositional environment influences the distribution and viability of prokaryotes.
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microscopic identification of prokaryotes in modern and ancient Halite saline valley and death valley california
Astrobiology, 2009Co-Authors: Brian A Schubert, Tim K Lowenstein, Michael N TimofeeffAbstract:Abstract Primary fluid inclusions in Halite crystallized in Saline Valley, California, in 1980, 2004–2005, and 2007, contain rod- and coccoid-shaped microparticles the same size and morphology as archaea and bacteria living in modern brines. Primary fluid inclusions from a well-dated (0–100,000 years), 90 m long salt core from Badwater Basin, Death Valley, California, also contain microparticles, here interpreted as halophilic and halotolerant prokaryotes. Prokaryotes are distinguished from crystals on the basis of morphology, optical properties (birefringence), and uniformity of size. Electron micrographs of microparticles from filtered modern brine (Saline Valley), dissolved modern Halite crystals (Saline Valley), and dissolved ancient Halite crystals (Death Valley) support in situ microscopic observations that prokaryotes are present in fluid inclusions in ancient Halite. In the Death Valley salt core, prokaryotes in fluid inclusions occur almost exclusively in Halite precipitated in perennial saline l...
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evaluating seawater chemistry from fluid inclusions in Halite examples from modern marine and nonmarine environments
Geochimica et Cosmochimica Acta, 2001Co-Authors: Michael N Timofeeff, Tim K Lowenstein, Robert V Demicco, Heide Zimmermann, Sean T. Brennan, Juske Horita, L E Von BorstelAbstract:Fluid inclusions from marine Halites have long been studied to determine the chemical composition of ancient seawater. Chemical analyses of the major ions in fluid inclusions in Halites from the solar saltwork of Great Inagua Island, Bahamas, and from the supratidal sabkha, Baja California, Mexico, show that modern marine Halites faithfully record the chemical signature of seawater. The major ions in Great Inagua and Baja California fluid inclusions display distinctive linear trends when plotted against one another (ie., Na+, K+, and SO42− vs. Mg2+ and Cl−), which track the evaporation path of seawater as it evolved during the crystallization of Halite. These evaporation paths defined for the major ions by fluid inclusions in Halite overlap findings of computer simulations of the evaporation of modern seawater by the Harvie, Moller, and Weare (HMW) computer program. The close match between the HMW seawater evaporation paths and the Great Inagua fluid inclusion data is not surprising considering the carefully controlled inflow, evaporation, and discharge of seawater at the Great Inagua saltwork. The major ion chemistry of fluid inclusions from the Baja California Halites matches the HMW seawater evaporation paths in most respects, but one Baja fluid inclusion has lower concentrations of Mg2+ than evaporated seawater. Nonmarine inflows and syndepositional recycling of preexisting salts in the Baja California supratidal setting were not large enough to override the chemical signature of evaporating seawater as the primary control on the Baja fluid inclusion compositions. Fluid inclusions in Halites from the nonmarine Qaidam Basin, Qinghai Province, western China, have a distinctly different major ion chemical signature than does “global” seawater. The fluid inclusion chemistries from the Qaidam Basin Halites do not lie on the evaporation pathways defined by modern seawater and can clearly be differentiated from fluid inclusions containing evaporated seawater. If fluid inclusions in Halites from modern natural settings contain unmistakable samples of evaporated seawater, then evaluation of the chemistry of ancient seawater by chemical analysis of fluid inclusions in ancient marine Halites by means of the same approach should be valid.
Ido Sirota - One of the best experts on this subject based on the ideXlab platform.
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temperature seasonality control on modern Halite layers in the dead sea in situ observations
Geological Society of America Bulletin, 2017Co-Authors: Ido Sirota, Yehouda Enzel, Nadav G LenskyAbstract:Layered Halite sequences are found in deep basins throughout the geological record. However, analogs for such sequences are commonly studied in shallow environments. Here, we studied active precipitation of Halite layers from the only modern analog for deep, Halite-precipitating basins, the hypersaline Dead Sea. In situ observations in the Dead Sea link seasonal thermohaline stratification, Halite saturation, and the characteristics of the actively forming Halite layers. The spatiotemporal evolution of Halite precipitation in the Dead Sea was characterized by means of monthly observations of (1) lake thermohaline stratification (temperature, salinity, and density), (2) degree of Halite saturation, and (3) textural evolution of the active Halite deposits. We present the observed relationships between the textural characteristics of layered Halite deposits (i.e., grain size, consolidation, and roughness) and the degree of saturation, which in turn reflects the limnology and hydroclimatology. The lake floor is divided into two principal environments: a deep, hypolimnetic lake floor and a shallow, epilimnetic lake floor. In the deeper hypolimnetic lake floor, Halite continuously precipitates with seasonal variations: (1) During summer, consolidated coarse Halite crystals form rough surfaces under slight supersaturation. (2) During winter, unconsolidated, fine Halite crystals form smooth lake floor deposits under high supersaturation. These observations support interpretations of the seasonal alternation of Halite crystallization mechanisms. The shallow epilimnetic lake floor is highly influenced by the seasonal temperature variations, and by intensive summer dissolution of part of the previous year’s Halite deposit, which results in thin sequences with annual unconformities. This emphasizes the control of temperature seasonality on the characteristics of the precipitated Halite layers. In addition, precipitation of Halite on the hypolimnetic floor, at the expense of the dissolution of the epilimnetic floor, results in lateral focusing and thickening of Halite deposits in the deeper part of the basin and thinning of the deposits in shallow marginal basins.
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seasonal variations of Halite saturation in the dead sea
Water Resources Research, 2016Co-Authors: Ido Sirota, Ali Arnon, Nadav G LenskyAbstract:Hypersaline lakes and seas were common in the past, precipitating thick evaporitic salt deposits. The only modern analogue for the paleo-limnology of deep salt-saturated aquatic environments exists in the Dead Sea. In this study we present new insights from the Dead Sea on the role of seasonal thermohaline stratification and water balance on the seasonal and depth variations of the degree of saturation of Halite (salt) and the rate of Halite growth along the water column. We developed methodologies to accurately determine the empirical degree of Halite saturation of the lake based on high accuracy densitometry, and to quantify Halite growth rate along the water column. During summer, the epilimnion is undersaturated and Halite is dissolved, whereas during winter the entire water column is supersaturated and crystallizes Halite. This result is not trivial because the variations in the water balance suggest the opposite; summer is associated with higher loss of water by evaporation from the lake compared to the winter. Hence, the thermal effect overcomes the hydrological balance effect and thus governs the seasonal saturation cycle. The hypolimnion is supersaturated with respect to Halite and crystallizes throughout the year, with higher super saturation and higher crystallization rates during winter. During summer, simultaneous opposing environments coexist – an under-saturated epilimnion that dissolves Halite and a supersaturated hypolimnion that crystallizes Halite, which results in focusing of Halite deposits in the deep hypolimnetic parts of the evaporitic basins and thinning the shallow epilimnetic deposits. This article is protected by copyright. All rights reserved.
Federico Orti - One of the best experts on this subject based on the ideXlab platform.
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glauberite Halite association of the zaragoza gypsum formation lower miocene ebro basin ne spain
Sedimentology, 2007Co-Authors: Josep Maria Salvany, Javier Garciaveigas, Federico OrtiAbstract:Glauberite is the most common mineral in the ancient sodium sulphate deposits in the Mediterranean region, although its origin, primary or diagenetic, continues to be a matter of debate. A number of glauberite deposits of Oligocene–Miocene age in Spain display facies characteristics of sedimentologic significance, in particular those in which a glauberite–Halite association is predominant. In this context, a log study of four boreholes in the Zaragoza Gypsum Formation (Lower Miocene, Ebro Basin, NE Spain) was carried out. Two glauberite–Halite lithofacies associations, A and B, are distinguished: association (A) is composed of bedded cloudy Halite and minor amounts of massive and clastic glauberite; association (B) is made up of laminated to thin-bedded, clear macrocrystalline, massive, clastic and contorted lithofacies of glauberite, and small amounts of bedded cloudy Halite. Transparent glauberite cemented by clear Halite as well as normal-graded and reverse-graded glauberite textures are common. This type of transparent glauberite is interpreted as a primary, subaqueous precipitate. Gypsum, thenardite or mirabilite are absent in the two associations. The depositional environment is interpreted as a shallow perennial saline lake system, in which chloride brines (association A) and sulphate–(chloride) brines (association B) are developed. The geochemical study of Halite crystals (bromine contents and fluid inclusion compositions) demonstrates that conditions for co-precipitation of Halite and glauberite, or for precipitation of Na-sulphates (mirabilite, thenardite) were never fulfilled in the saline lake system.
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Modern halolites (Halite oolites) in the Tuz Gölü, Turkey
Sedimentary Geology, 2007Co-Authors: Erdoğan Tekin, Turhan Ayyildiz, İbrahim Gündoğan, Federico OrtiAbstract:Abstract Halite oolites (halolites) and pisoids (halopisoids) precipitate yearly (in summer) in the brine conduits of the saltpans in the Tuz Golu saline lake (Central Anatolia, Turkey). These halolites are well rounded and spherical, ranging between 0.7 and 2 cm in size. They are composed of coarse-grained Halite crystals as the nucleus, and by concentric Halite laminae with a radial fabric as the cortex. The cortex is subdivided into inner, middle, and outer zones, each zone showing different mineralogical and morphological features. These features include the presence of: organic matter particles, native sulphur globules, gypsum–anhydrite–calcite laminae, quartz–chlorite–celestite–thermonatrite laminae, submicroscopic Halite crystals, and microborings, cavities and corrosion-like structures. Our observations in the Tuz Golu saltpan environment and in the halolite fabrics suggest that (1) an intermittent supply of heavy brines from the saline lake into the saltpan conduits, which occur under agitated conditions during pumping operations, is the main genetic reason for the halolite formation; and that (2) physical, chemical and biological factors exert a significant influence on the mineralogical–textural complexity of the cortex.
