John Hellstrom

Speleothems formed from salt, sulfur and other minerals are also known. Speleothems made of pure calcium carbonate are a translucent white color, but often speleothems are colored by chemicals such as iron oxide , copper or manganese oxide , or may be brown because of mud and silt particulate inclusions. Chemistry[ edit ] Many factors impact the shape and color of speleothem formations including the rate and direction of water seepage, the amount of acid in the water, the temperature and humidity content of a cave, air currents, the above ground climate, the amount of annual rainfall and the density of the plant cover. Most cave chemistry revolves around calcium carbonate CaCO3 , the primary mineral in limestone and dolomite. It is a slightly soluble mineral whose solubility increases with the introduction of carbon dioxide CO2. It is paradoxical in that its solubility decreases as the temperature increases, unlike the vast majority of dissolved solids. This decrease is due to interactions with the carbon dioxide, whose solubility is diminished by elevated temperatures; as the carbon dioxide is released, the calcium carbonate is precipitated.

New Science Research Shows Dangerous Carbon Lurking in Permafrost

Get this from a library! Beginning with naturally occurring uranium , this series includes the following elements: Its Uses and Hazards – Institute for Energy and First discovered in the 18th century, uranium is an element found everywhere on Earth, but mainly in trace quantities. For any science, and particularly for the Earth Sciences, Contact Supplier Uranium—thorium dating – Wikipedia Uranium—thorium dating, also called thorium dating, uranium-series disequilibrium dating or uranium-series dating, is a radiometric dating technique established in the s which has been used since the s to determine the age of calcium carbonate materials such as speleothem or coral.

Uranium and thorium geochemistry is described in application to U-series dating of speleothems by the Th/U, Pb/U, and U/U methods.

Such “speleothems” are usually regarded to be a most suitable material for dating purposes, and they are not altered as is bone material after long times of storage. Uranium series dating seems to be a most reliable and rather frequently used technique to determine the formation age of such speleothems. A few other methods have been applied, but of these only C , thermoluminescence and electron spin resonance proved to be quite successful as well. Out of the three very long lived daughter nuclides of the U-decay series the isotope Th is commonly believed to be the most useful one for dating via radioactive disequi- libria.

The trace element uranium is easily dissolved and transported by karstic, carbonate-rich waters seeping through the limestone rock. Thorium, however, is tightly adsorbed by clay minerals always present in the hair-cracks and crevices of the roof limestone. It is for that reason that in the members of the U series fig. This raising ratio can be seen on figure 3, which also demonstrates a certain influence caused by the initial a- activity ratio of the uranium isotopes U to U , shortly called “ro”.

Each single growth zone is then dissolved in HC1 or HNO3, and the trace amounts of uranium and thorium are separately isolated by means of a specially developed chemical procedure fig. Artificially produced isotopes U and Th are added as tracers for the different uranium and thorium yields.

Finne, Martin

Arts and Entertainment Dating and DNA show Paleoamerican-Native American connection Cave diver Alexandro Alvarez inspects the newly-discovered skull of Naia, the 12, , year-old human skeleton discovered in a submerged cave on the Yucatan peninsula of Mexico. An international team of researchers detailed their analysis of what is the oldest most complete, genetically intact human skeleton in the New World in a paper published today in the journal Science. Now an international team of researchers has identified a nearly complete Paleoamerican skeleton with Native American DNA that dates close to the time that people first entered the New World.

Alberto Nava Blank and a team of science divers discovered the skeleton along with many extinct animal remains deep inside this inundated cave in The divers named the girl Naia.

uranium-thorium popular funny dating video dating of corals. Dating carbon dating and other cosmogenic methods the occurrence of natural radioactive carbon in the atmosphere provides a unique opportunity to materials as old as roughly 60, years.

Others Cave popcorn , or cave coral, are small, knobby clusters of calcite Cave pearls are the result of water dripping from high above, causing small “seed” crystals to turn over so often that they form into near-perfect spheres of calcium carbonate Snottites are colonies of predominantly sulfur oxidizing bacteria and have the consistency of “snot”, or mucus [3] Calcite rafts are thin accumulations of calcite that appear on the surface of cave pools Speleothems may also occur in lava tubes.

Although sometimes similar in appearance to speleothems in caves formed by dissolution, these are formed by the cooling of residual lava within the lava tube. Speleothems formed from salt, sulfur and other minerals are also known. Speleothems made of pure calcium carbonate are a translucent white color, but often speleothems are colored by minerals such as iron , copper or manganese , or may be brown because of mud and silt particulate inclusions.

Chemistry Many factors impact the shape and color of speleothem formations including the rate and direction of water seepage, the amount of acid in the water, the temperature and humidity content of a cave, air currents, the above ground climate, the amount of annual rainfall and the density of the plant cover. Most cave chemistry revolves around calcite ; CaCO3, the primary mineral in limestone.

It is a slightly soluble mineral whose solubility increases with the introduction of carbon dioxide , CO2. It is paradoxical in that its solubility decreases as the temperature increases, unlike the vast majority of dissolved solids. This decrease is due to interactions with the carbon dioxide, whose solubility is diminished by elevated temperatures; as the carbon dioxide is released, the calcium carbonate is precipitated.

Most other solution caves that are not composed of limestone or dolostone are composed of gypsum calcium sulfate , the solubility of which is positively correlated with temperature. As climate proxies Samples can be taken from speleothems to be used like ice cores as a proxy record of past climate changes. Stalagmites are particularly useful for palaeoclimate applications because of their relatively simple geometry and because they contain several different climate records, such as oxygen and carbon isotopes and trace cations.

Absolute dating Main article: Absolute dating Another dating method using electron spin resonance ESR — also known as electron paramagnetic resonance EPR — is based on the measurement of electron-hole centers accumulated with time in the crystal lattice of CaCO3 exposed to natural radiations.

Pleistocene Permafrost Thawing History of Alaska, the Yukon, and the Northwest T

This is an open access article distributed under the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Islands situated to the south of India receive, therefore, the first and last showers of the monsoon; speleothems in such islands have not yet been explored for their potential to reconstruct past monsoon rainfall.

The aim was to detect i whether these samples are amenable to dating using 14C, ii whether their oxygen isotopes indicate precipitation under isotopic equilibrium, and iii if i and ii above are true, can we reconstruct monsoon activity during the past few millennia?

Our ICP-MS data, including uranium standards, thorium standards, U–U–Th–Th dating of speleothems and Th– Th in oceanic particulates, replicates measurements made by thermal ionization mass spectrometry.

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Environmental research at archaeological site

This carbon may be vulnerable to thaw and release to the atmosphere as methane under a warming climate, making permafrost thaw one of the potentially most significant amplifying feedbacks to anthropogenic warming. Nonetheless, permafrost can be slow to respond to warming, the short instrumental record may not adequately capture long-term trends, and the modest temperature changes of the past few millennia provide poor analogues to understand the possibility of crossing climate thresholds in the next century or beyond.

One way to address this problem is to assess the stability of permafrost during previous interglacial periods of varying levels of warmth, which provide natural experiments to examine the Arctic’s sensitivity to warming. Cave speleothems in the Arctic are relics of past periods of thaw that enabled meteoric water to seep into caves and deposit calcite. We employed uranium-thorium U-Th dating to constrain the chronology and extent of permafrost thaw in the North American Arctic during the past , years.

We sampled caves from a range of permafrost zones and latitudes, including the Fishing Branch Territorial Park, Yukon

Drill cores carefully re-covered from the base of eleven speleothems, from which small subsamples were analysed using the Uranium-Thorium method, yielded ages between and kyr (1 kyr.

Instagram Science Our aim is to investigate past climate and environmental changes in Greenland using mineral and sedimentary deposits founds in caves. In doing so, we are constructing the first cave-based climate records for Greenland and the wider High Arctic, as well as improving our understanding of climate change during times and in places that are beyond the limit of the ice cores. Why is this important? The Arctic region is expected to experience some of the greatest climate and environmental changes in the next centuries as a result of climate change, and the consequences of these changes will be experienced worldwide, for instance through rising sea-levels or changes to Northern Hemisphere weather systems.

Improving understanding of how the Arctic will develop in a warmer world is therefore of paramount importance, and one way to achieve this is to look at periods of warmer climate in the recent geological past. Understanding how the climate has changed in the past can be achieved by investigating a number of different geological archives, as well as by running sophisticated climate models on computers.

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A Journey to the Oldest Cave Paintings in the World The discovery in a remote part of Indonesia has scholars rethinking the origins of art—and of humanity Dr. Maxime Aubert, archeologist and geochemist, uses his headlamp to examine the cave art at Leang Lompoa in Maros, Indonesia. The stalks, almost ready to harvest, ripple in the breeze, giving the valley the appearance of a shimmering green sea.

In the distance, steep limestone hills rise from the ground, perhaps feet tall, the remains of an ancient coral reef. Rivers have eroded the landscape over millions of years, leaving behind a flat plain interrupted by these bizarre towers, called karsts, which are full of holes, channels and interconnecting caves carved by water seeping through the rock.

Our Reporter Was One of Them.

Speleothems typically form in limestone or dolostone solutional caves. The term “speleothem” as first introduced by Moore in this regard is their unique ability to be accurately dated over much of the late Quaternary period using the uranium-thorium dating technique.

Prehistoric Hearth, Runberg Site, Chaffee County Dead on the Stand Tree, Larimer County Share article to Radiocarbon dating of wood from dead-on-the-stand trees will yield a date that may be much older than the archaeological feature that is being dated. Dead on the Stand Tree, Larimer County Body Full Article Radiocarbon dating is the most common technique used in ascertaining the age of archaeological and paleontological sites during the last 45, years.

Developed by a chemist born in Colorado, there are now commercial and academic laboratories across the globe that conduct radiocarbon dating. Radiocarbon dating has made a substantive contribution to our understanding of Colorado prehistory by allowing archaeologists to place excavated sites in chronological order and allowing comparison of contemporary archaeological cultures. Development While Willard Libby received the Nobel Prize in Chemistry in for his contributions to the development of the radiocarbon dating method, the process that led to the discovery of this method began much earlier.

It had been shown that 14C is continually being produced by cosmic rays colliding with atmospheric nitrogen. Libby surmised that traces of 14C could always be found in carbon dioxide in the air. Carbon is absorbed by plants through photosynthesis. After a plant died, it could no longer absorb 14C.

Scientists find stable sea levels during last interglacial

When an igneous melt crystallizes, parent and daughter elements are chemically separated into different crystals. Further radioactive decay keeps the parent and daughter elements in the same crystal. Setting the Radiometric Clock Individual crystals of the same mineral are dated to give the age of crystallization or cooling. Examples include zircon, muscovite, and biotite. Note that whole rock analysis would not give the age of cooling.

Uranium-Thorium dating is based on the detection by mass spectrometry of both the parent ( U) and daughter ( Th) products of decay, through the emission of an alpha particle. The decay of Uranium to Thorium is part of the much longer decay series begining in U and ending in Pb.

Speleothems Show Warmer Past Date: They provide an archive of climate variations from which indications of mean temperature, rainfall and sometimes surface vegetation data can be extracted on timescales from the subannual to the millennial. They can be remarkably well preserved for millions of years. Speleothems have a unique ability to be accurately dated over much of the late Quaternary period using the uranium-thorium dating technique.

Stalagmites are particularly good because of their relatively geometry and because they contain several different climate records, such as oxygen and carbon isotopes and trace cations. Prompted by a paper published in the journal Nature looking at speleothem data for China over the past few hundred thousand years Willis Eschenbach looked at the freely available speleothem data from the NOAA Paleoclimatology web site paying attention to the past 10, years — the period covering the emergence from the last strong phase of the Ice Age.

Although based on straightforward calibration the graph produced is fascinating and would be unlikely to change with more detailed processing of the data. It shows that speleothem data indicates that it was considerably warmer 7, years ago than it is today. Click on image to enlarge.

Ancient Cave Formations Reveal History of Abrupt Climate Changes

Hyde and Stewart were asked to rig two people so they’d hang in mid-air, in front of a green screen, as part of a commercial video. It went well, even though we had to get inventive and establish a way to suspend someone in a climbing harness clipped in at their upper back in a vertical position. And, of course, we now have about 15 metres of 9mm static rope painted green – but it’s latex, and we think it will wash off with a bit of effort The production crew, and “Talent”, were very cool, and it was fun to work with them.

We managed to record a little of our own video in the course of it, posted on YouTube at: We’ll be back to the real mission, speleology, next weekend.

their daughter isotopes (Th and Pa) allow the dating of speleothems using either Uranium-Thorium or Uranium Protactinium dating series (Langmuir, ; Dorale et al., 2. ). This provides a temporal framework for paleoclimate analysis, and allows.

Comment The frosty dungeon hides a dark secret. At least a quarter of the Northern Hemisphere’s landmass is frozen and, like a vault, it holds 1, gigatonnes of carbon. This unimaginably high quantity of carbon comes from countless generations of creatures that have lived and died in the area over millions of years. A portion of those dead plants and animals weren’t decomposed by microorganisms because, at a certain point, it was simply too cold for that. But the permafrost is slowly melting. If large areas of ground underneath were to thaw one day, the bacterial decomposition process would pick up where it left off, releasing huge amounts of greenhouse gases.

In total, permafrost contains twice as much carbon as what is currently billowing through the Earth’s atmosphere. If major portions of that carbon become released, the world’s climate would suffer fatal consequences.

GeoBlogy: Caves hold clues to past climate by Laura Deeprose

Uranium-Thorium dating is based on the detection by mass spectrometry of both the parent U and daughter Th products of decay, through the emission of an alpha particle. The decay of Uranium to Thorium is part of the much longer decay series begining in U and ending in Pb. With time, Thorium accumulates in the sample through radiometric decay.

Uranium-series dating measures equilibrium between uranium and thorium and is used quite a bit in corals and speleothems. Uranium is soluble in water, thorium is not (at least not at natural temps and pressures) but U decays to Th through alpha decay at a known rate.

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Seawra Cave Speleothems


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