Showing papers on "Speleothem published in 2003"

Precise dating of Dansgaard–Oeschger climate oscillations in western Europe from stalagmite data

Abstract: The signature of Dansgaard-Oeschger events--millennial-scale abrupt climate oscillations during the last glacial period--is well established in ice cores and marine records. But the effects of such events in continental settings are not as clear, and their absolute chronology is uncertain beyond the limit of (14)C dating and annual layer counting for marine records and ice cores, respectively. Here we present carbon and oxygen isotope records from a stalagmite collected in southwest France which have been precisely dated using 234U/230Th ratios. We find rapid climate oscillations coincident with the established Dansgaard-Oeschger events between 83,000 and 32,000 years ago in both isotope records. The oxygen isotope signature is similar to a record from Soreq cave, Israel, and deep-sea records, indicating the large spatial scale of the climate oscillations. The signal in the carbon isotopes gives evidence of drastic and rapid vegetation changes in western Europe, an important site in human cultural evolution. We also find evidence for a long phase of extremely cold climate in southwest France between 61.2 +/- 0.6 and 67.4 +/- 0.9 kyr ago.

Uranium-series Chronology and Environmental Applications of Speleothems

Abstract: An increasing number of scientists recognize the value of speleothems1 as often extremely well-preserved archives of information about past climate, vegetation, hydrology, sea level, nuclide migration, water-rock interaction, landscape evolution, tectonics and human action. Well-constrained data are required to document past changes, reconstruct past patterns and predict future responses of the Earth system at a wide range of spatial and temporal scales. Speleothems are particularly useful in this regard because they can be found in many locations of the globe, sampled at high-resolution and reliably dated using high-precision uranium-series techniques. Speleothems are bodies of mineral material formed in caves as the result of chemical precipitation from groundwater flowing or dripping in a cave. Most speleothems are composed of calcite formed by slow degassing of CO2 from supersaturated groundwater, but aragonite and gypsum forms are also common, particularly near cave entrances where evaporative effects are important. A host of different speleothem types decorate the walls, ceilings and floors of caves, and their mineralogy and morphology is a function of fluid flow and chemistry of waters feeding a particular location as well as the ambient conditions (temperature, chemistry, light) in the air or water-filled void. Subaerial forms include the familiar stalagmites, stalactites, draperies, flowstones. Subaqueous forms include rimstone pools, “rafts,” mammillary calcite wall-coatings and “dog-tooth” spar. For an extensive review of the types of speleothem that have been observed, see Hill and Forti (1997). Speleothems are used in a multitude of ways to explore past environmental conditions, perhaps the most fundamental of which is their very presence or absence. Deposition of speleothems relies on sufficient water supply and soil CO2 to enable dissolution and transport of reactants in the vadose zone to underlying caves. In arid or glacial times, conditions may not have been favorable for speleothem formation. …

Uranyl Incorporation in Natural Calcite

Abstract: The occurrence of trace amounts of uranyl in natural calcite has posed a long-standing problem in crystal chemistry because of speculation that the size and shape of the uranyl ion may preclude its incorporation in a stable lattice position in calcite. This also defines an important environmental problem because of its bearing on the transport and sequestration of uranyl released from nuclear facilities and uranium mining operations. Calcite is a nearly ubiquitous mineral in soils and groundwater aquifers. X-ray absorption spectroscopy and X-ray fluorescence microprobe studies of uranium in relatively U-rich ∼13 700-year-old calcite from a speleothem in northernmost Italy indicate substitution of uranyl for a calcium and two adjacent carbonate ions in calcite. These new data imply that uranyl has a stable lattice position in natural calcite, indicating that it may be reliably sequestered in calcite over long time scales.

How speleothems grow: an introduction to the ontogeny of cave minerals

Abstract: Speleothems are secondary mineral deposits that form in caves (Moore 1952). This distinguishes them from primary mineral bodies such as the bedrock that encloses the cave, mineral veins in the bedrock, and sediments accumulated in the cave. These primary minerals are important as sources of material from which new mineral bodies (speleothems) can grow in response to specific physical and chemical processes operating within the cave. A cave mineral is a homogeneous solid having a definite chemical composition and a 3-D ordered atomic arrangement, growing naturally as a secondary mineral deposit within a cave. More than 250 cave minerals are known (Hill & Forti 1997) but only 3 (calcite, aragonite, and gypsum) can be considered common. The term cave mineral refers to the mineral species of a deposit, whereas speleothem terms (such as stalactite, cave pearl, etc.) are used to describe their morphology. Neither of these terminology systems defines the growth mechanisms of speleothems or their genetic history. The study of the origin and evolution of mineral bodies is

Open-system alpine speleothems; implications for U-series dating and paleoclimate reconstructions

Abstract: Open-system alpine speleothems: implications for U-series dating and paleoclimate reconstructions The present work is a critical review of 130 alpha-spectrometric U/Th analyses of speleothems from north-eastern Italy. About 33% of measurements display activity ratios (Th/U)>1 while maintaining (U/U) close to unity, thus falling outside the closed system U-series disequilibrium fi eld. The open-system behaviour was mostly observed in speleothems that, based on geological data and petrographic observations, have experienced dramatic environmental changes, such as fl ooding of caves by glacial meltwater or dissolution by undersaturated waters. The paper discusses possible causes of the open-system behaviour in the U-Th system, and evaluates evidence for the U leaching vs. Th introduction. By considering only samples which do not show the open-system behaviour and are not contaminated by detrital thorium, fi ve periods of active speleothem deposition have been identifi ed for north-eastern Italy: 0 to 10 ka, 40 to 63 ka, 88 to 100 ka, 140 to 160 ka, and 190 to 250 ka. Even in these, apparently good, data set, the ages of 140 to 160 ka might be affected by undetected Th introduction, since they appear to be 20 to 40 ka older than the data obtained for the same paleoclimate period from European speleothems.

Nuclear microprobe analysis of uranium-rich speleothems: Methodological aspects

Abstract: The study of the chemical composition of speleothems, calcium carbonate concretions, can reveal past climatic and environmental changes. We investigated the micro-chemical distribution of trace elements in speleothems formed of an unusual mixture of calcite and aragonite, originating from the Aranzadi gallery, ‘Gouffre de La Pierre-Saint-Martin’, Pyrenees, France. PIXE and RBS were performed simultaneously with a 3.0 MeV proton beam, focused down to 5.0 μm diameter. Quantitative element mapping revealed that U and Sr concentrations were the highest ever observed in speleothems of meteoric origin. Moreover, within the same samples, Sr and U were more concentrated by a factor 10 in aragonite mineral phase than in calcite. This can be explained by the crystalline orthorhombic structure of aragonite that presents a site of coordination wider than in calcite allowing to trap large cations such as Sr 2+ and (UO 2 ) 2+ . These results helped to raise new hypothesis on the very specific growth conditions of some speleothems from the Aranzadi gallery.

Isotopic records from ground-water and cave speleothem calcite in North America

Abstract: Publisher Summary This chapter provides an overview of the stable isotope records of Quaternary paleoclimate from calcite formed in the presence of ground water descending through the vadose zone and within the saturated zone. Cave speleothems and Devil's Hole (DH) calcite can be viewed as two end-member expressions of a single ground-water flow continuum. Three important isotope records from ground-water calcites, two from Devils Hole and one from nearby Death Valley, have come out of the Mojave Desert. The best-known ground-water calcite records in the region come from two cores obtained by scuba divers at DH. The whole issue of how globally representative the DH record is remains unclear, and awaits, in part, the development of ground-water calcite and speleothem records outside of southwestern North America. Speleothems remain one of the most datable of Quaternary continental records, and other aspects of the deposits, such as the age distributions and growth rates; however, the apparent potential for annual or semi-annual banding, and the use of δ13Cc values in paleovegetation reconstruction will continue to attract researchers to speleothem study.

Prevention of speleothem rupture during nearby construction

Abstract: The cave of Milandre, located in the Swiss Jura, is characterised by a rich speleothem popula- tion. Some of the most decorated galleries lie at low depth (40-50 m). A new highway will be built, with a tunnel, just over a decorated part of the cave. In order to prevent damage in the cave, a study was conducted in the framework of the impact study. One of the goals was to evaluate the risk of speleothem rupture caused by explosive shots that will be used to excavate the tunnel portal. To this end, the speleothems' vulnera- bility to ground shaking was compared with the observed accelerations induced by experimental explosions. This procedure allowed to determine maximum acceptable explosive charges.

Bacterial influence on speleothem oxygen isotope composition : an example based on cave pisoids from Perlová Cave (Slovakia)

Abstract: The origin of recently growing irregular cave pisoids in Perlova Cave (Vefka Fatra Mts, Slovakia) seems to be due to the activity of hydrogen-oxidizing bacteria. Several samples of water and freshly deposited calcite from cave pisoids were analysed for stable oxygen isotope ratios. The obtained values were checked using the O’Neil equation. Almost all the calcite samples display values more positive than their calculated counterparts. This phenomenon is ascribed to a fractionation process mediated by bacteria. The light isotope of oxygen is preferentially taken up by the hydrogen-oxidizing bacteria. It causes the relative enrichment in the heavy isotope in the bacterias’ surroundings, which is recorded in the calcite precipitated around the bacterial cells.

Littoral dripstone and flowstone — non-spelean carbonate secondary deposits

Abstract: Speleothem-like dripstone and flowstone deposits can form in the non-spelean environments of marine notches on tropical carbonate coastlines. Hereby termed “littoral dripstone” and “littoral flowstone” to distinguish them from genuine cave deposits, they reflect the basic speleothem types: draperies, stalactites, stalagmites, and columns. Nevertheless, these formations lack the luster and crystallinity of cave analogues, and are not nearly as well-developed, dense, and massive. They are composed of layered microcrystalline aragonite and calcite, are generally highly porous, and invariably overlie dissolutional and bioerosional karren. Because true speleothems, often found in the remnants of solution voids breached by coastal erosion, are also commonly present in the modern littoral environments on tropical carbonate islands, they could be confused with littoral dripstone and flowstone deposits. The distinction between the two is crucial, because the true speleothems are indicators of karst cave paleoenvironments, while littoral dripstone and flowstone are contemporary parts of the modern coastal landscape.

Implicaciones paleoclimáticas de la distribución geocronológica de espeleotemas en la Cueva del Cobre (Palencia)

Abstract: Twenty two Uranium-series datings carried on seven stalagmites collected in the cold, high mountain karstic system of Cueva del Cobre (Cantabrian Mountains, N Spain) allow to distinguish three phases of major growth frequency of speleothems in the cave for the last 150 ky. This difference in growth frequency is interpreted to be climatically induced: stalagmite growth was impeded during the coldest time intervals when the cave was probably cavered by a mountain glacier and, on the contrary, their maximum growth took place during warmer humid episodes. This hypothesis is supported by the correlation of the speleothem growth frequencies with the oxygen isotopic stages of the late Quaternary.

Ranges (amplitudes) of isotopic ratios in speleothems, with particular reference to samples from the centre of North America

Abstract: This paper compares unstable and stable isotope ratios measured in a speleothem core from the Nevada desert (the well-known DH 11) with speleothems at the centre of the continent in the Black Hills of South Dakota. All samples grew over most of the past 500,000 y. The thermal calcite in the large Nevadan desert basin displays a range of the initial U ratio ( 234 U/ 238 U0) of only 0.25 and is much enriched in 234 U, reflecting selective leaching in a very low energy weathering environment. Similar thermal calcite from a much smaller basin the Black Hills (Wind Cave) is less homogenised (U/U0 range is ~0.5) and less enriched as a consequence of its more vigorous sem-arid weathering environment. Both display glacial-interglacial cyclicity in the ratio. A vadose speleothem from Jewel Cave, Black Hills, has a U/U 0 range of 0.75 and many erratic features attributable to rapidly changing local conditions in the overlying tall grass- coniferous forest vegetal transition. O and C stable isotopes are again homogenised in the large Nevada basin: the range is 2.8 ‰ 18 O and 1.2 ‰ 13 C, encompassing all glacial-interglacial cyclicity. In the Wind Cave thermal calcites the range again is roughly double, an effect of lesser homogenisation taking place in the smaller aquifer. There is also a perturbation of the signals of ~100 ky duration that may have been caused by release of deep CO 2 . 18 O and 13 C measurements in the Jewel Cave vadose sample form a broad envelope that encloses the Black Hills thermal calcite data, indicating that the full range, glacial – interglacial, of speleothem 18 O was probably 10 ‰ here in the centre of the continent, which may be compared to 1.2 ‰ estimated at the sources of the precipitation in the Gulf and Caribbean. 13 C of the vadose speleothem ranged 7.0 ‰ in the Black Hills, oscillating between moderate and very low (desert-like) levels of soil CO 2 activity.

Formation period and environment of speleothem in the liujiang basin inferred from the shanyangzhai mammal fossils

Abstract: Shanyangzhai speleal sediment which contains plenty of mammal fossils is one of the speleothem in the Liujiang Geological Remain Reservation Zone in Qinhuangdao of Hebei Province.Based on the fossil excavation and identification,the biostratigraphy and correlation analysis of the living habit of the mammals indicate that the chronology is Qp23,later than lower Jinniushan Formation fauna in Liaoning Province and earlier than Qian'an Zhaocun fauna in Hebei Province and Shalawusu fauna in the Inner Mongolia.It reflects the characteristics of mammals in the transition zone from North China to Northeast China during late Qp2 and early Qp3.The characteristics of the mammal fauna reflect the time and space variation of ecological environments such as forest,grass and water bodies in this area.This is the first time to found such plenty of mammal fossils in this area, which enriches the variety and value of geological remain resources in the reservation zone and provides a basis for studying the chronology and environment of speleothem.It also corrects the misunderstanding that the speleothem in this area only consists of Qp2 sediments.

The development of tourist caves in the kingdom of saudi arabia

Abstract: 1 ARABIC ABSTRACT 2 INTRODUCTION 3 GENERAL CHARACTERISTICS OF CAVES IN SAUDI ARABIA 3 THE CAVES OF THE AS SULB PLATEAU 4 FRIENDLY CAVE 6 SURPRISE CAVE 8 KAHF AL RUTUWBAH/GECKO CAVE 13 THE NATURAL COOLER OF MURUBBEH CAVE 15 CAVES OF THE FAR NORTH 23 LAVA-TUBE CAVES 23 PROBLEMS OF DEPLETION AND SAFEGUARD OF DESERT CAVES 24 SAUDI SOCIETY AND SPELEOLOGICAL TOURISM 26 THE DEVELOPMENT OF A SHOW CAVE IN A DESERT 26 PROCEDURES REQUIRED FOR TOURIST CAVE DEVELOPMENT 28 TIME TABLE FOR TOURIST CAVE DEVELOPMENT IN THE KINGDOM 28 CALCULATING COSTS 29 POTENTIAL TRAFFIC AND INCOME FROM TOURIST CAVES IN THE KINGDOM .....30 RELATION OF TOURIST CAVE DEVELOPMENT TO AQUIFER PROTECTION 30 RELATION OF TOURIST CAVE DEVELOPMENT TO CAVE AND KARST PROTECTION 31 FINAL REMARKS 31 ACKNOWLEDGMENTS 31 REFERENCES 31 APPENDICES ILLUSTRATIONS FIGURES Figure 1. Geological map of Saudi Arabia showing the As Sulb karst region, the area with the highest known concentration of limestone and lava caves. 4 Figure 2. A tray speleothem found in Surprise Cave, featuring clusters of popcorn on grape coralloids and frostwork resting on a flat, horizontal tray-like surface 5 Figure 3. Map of Friendly Cave. 6 Figure 4. The entrance to Friendly Cave is large enough for the insertion of a circular staircase...6 Figure 5. The strategic use of lamps in this picture demonstrates how proper lighting can make Friendly Cave very attractive for tourism. 7

U-series Dating of a Speleothem from Inazumi Cave, Oita Prefecture, Japan

Abstract: Trace quantities of uranium and thorium were separated from a submerged calcite speleothem (stalactite) sample from Inazumi Cave, Oita Prefecture, using Fe (OH) 3 coprecipitation followed by anion-exchange separation with HNO3 and HCl. The isotope ratios 234U/238U and 230Th/234U were determined by isotope-dilution thermal ionisation mass spectrometry. The speleothem became submerged by accumulation of the Aso welded-tuff, Aso-4, and a resulting rise in the local water table that occurred 85, 000-89, 000 years ago. The age of the analysed portion of the sample was 170, 000 years B.P., suggesting that it was deposited before the earlier Aso-2 and-3 eruptions and has been submerged at least three times.