Best radiometric dating is based on answers

best radiometric dating is based on answers

Radiometric dating is often used to “prove” rocks are millions of years old. Once you understand the basic science, however, you can see how wrong assumptions lead to incorrect dates. Shop Now. Radiometric Dating 101. PART 1: Back to Basics. PART 2: Problems with the Assumptions Yet this view is based on a misunderstanding of how radiometric dating works. Part 1 (in the previous issue) explained how scientists observe unstable atoms changing into stable atoms in the present. Part 2 explains how scientists run into problems when they make assumptions about what happened in the unobserved past. The Hourglass “Clock”—An Analogy for Dating Rocks. An hourglass is a helpful analogy to explain how geologists calculate the ages of rocks.

best radiometric dating is based on answers

Radiometric dating is a much misunderstood phenomenon. Evolutionists often misunderstand the method, assuming it gives a definite age for tested samples. Creationists also often misunderstand it, claiming that the process is inaccurate.

Radiometric Dating Is Not Inaccurate Perhaps a good place to start this article would be to affirm that radiometric dating is not inaccurate. It is certainly incorrect, and it is certainly based on wrong assumptions, but it is not inaccurate.

What do I mean? How can something be accurate and yet wrong? To understand this point, we need to understand what exactly is being measured during a radiometric dating test. One thing that is not being directly measured is the actual age of the sample. No “Age-Meter” There is no “age-meter” that you can plug into a rock, giving an immediate read-out of the rock’s age. It needs to be remembered that observational science can only measure things in the here-and-now, in a manner which can be repeated.

Historical science is concerned with trying to work out what may have happened in a one-off event in the past. Historical science is not capable of repetition, checking or peer—˜review. The age of a rock sample falls under the heading of historical science, not observational science. So what do the observational scientists in the radiometric dating lab do?

Radioactive isotopes are unstable and will decay into more stable isotopes of other elements. One common radiometric dating method is the Uranium-Lead method. This involves uranium isotopes with an atomic mass of 238.

This is the most common form of uranium. It decays by a 14-step process into lead-206, which is stable. Each step involves the elimination of either an alpha or a beta particle. Therefore the process is: Uranium Decay Equation Each individual atom has a chance of decaying by this process. If you were able to examine just one atom, you would not know whether or not it would decay. The chance of it decaying is not definite, by human standards, and is similar to the chance of rolling a particular number on a dice.

Although we cannot determine what will happen to an individual atom, we can determine what will happen to a few million atoms. This is similar to our dice analogy. We cannot tell what number we will roll in any one shake, but if we rolled 6,000 dice, the chances are very high that 1,000 of them would have landed on a six. One dice is unpredictable. Many dice follow a statistically predictable pattern. In the same way, one U-238 atom is unpredictable, but a sample containing many millions of U-238 atoms will be very predictable.

What happens statistically is that half of the available atoms will have decayed in a given period, specific to each radioactive species, called the half-life.

For example, if element Aa had a half-life of 1 day and we had 1,000 lbs. of it on Monday, then we would have 500 lbs. on Tuesday, 250 lbs. (half of 500) on Wednesday and 125 lbs. on Thursday. Determining Half-Life By observing how fast U-238 decays into lead-206, we can calculate the half-life of U-238. This is a theoretical calculation, and we can therefore determine that the half-life of U-238 is 4.5 billion years. Remember that the half-life is a statistical measure.

Granting that U-238 has a half-life of 4.5 billion years in no way negates the idea that the Earth is only 6,000 years old. A very common rock that contains U-238 is granite. If we look at some of the very small zircon crystals in granite, we can accurately measure how much U-238 and Pb-206 the crystal contains.

In order to calculate the age of the rock, we need three other pieces of information: • We need to know how fast the U-238 turns into Pb-206. The half-life gives us this value, provided the half-life has never altered during the lifetime of the zircon crystal. • We need to know how much Pb-206 there was in the original rock. This is clearly impossible. It is usually assumed, without justification, that the original quantity of Pb-206 in the rock was zero.

• We need to be sure that no lead compounds have been added to or taken away from the rock. Given that lead compounds are fairly soluble in water, this is something that we cannot be very sure of. Using the above assumptions, it is calculated that the zircon crystals have an age of about 1.5 billion years. Based Upon Assumptions The radioactive decay process above can be seen to produce 8 alpha-particles for each one atom of U-238. Each α-particle could gain new electrons and become an atom of helium.

The rate of diffusion of helium from a zircon crustal can be measured. It turns out that this rate of diffusion of helium is compatible with the crystals being about 5,000 years old, not 1.5 billion years old. Although assumptions 2 and 3 are not provable, they actually seem very likely in this particular example.

Therefore, it seems that the first assumption must be wrong . Remember that we have already said that these experimenters are highly skilled. It is therefore unlikely that the laboratory technicians have made a mistake in their measurements of U-238 or Pb-206. The only possible conclusion, therefore, is that the half-life of U-238 has not been constant throughout the lifetime of the granite and its zircon crystals.

Other radiometric dating methods are based on similar assumptions. If the assumptions cannot be trusted, then the calculations based on them are unsound. It is for this reason that creationists question radiometric dating methods and do not accept their results.

• For more on this important work, please see Humphreys, R., Young Helium Diffusion Age of Zircons Supports Accelerated Nuclear Decay, in Vardiman, L., Snelling, A.A., and Chaffin, E.F. (2005), Radioisotopes and the Age of the Earth, Volume 2, (California: Institute for Creation Research), pages 25-100. Eric Hovind grew up immersed in the world of apologetics and following college graduation in 1999, he began full-time ministry. President and Founder of Pensacola-based organization, Creation Today, Eric’s passion to reach people with the life-changing message of the Gospel has driven him to speak in five foreign countries and all fifty states.

He lives in Pensacola, Florida with his wife Tanya and three children and remains excited about the tremendous opportunity to lead an apologetics ministry in the war against evolution and humanism.


best radiometric dating is based on answers

best radiometric dating is based on answers - Radiometric Dating: Problems with the Assumptions


best radiometric dating is based on answers

The way it really is: little-known facts about radiometric dating Long-age geologists will not accept a radiometric date unless it matches their pre-existing expectations. by morgueFile.com/RoganJosh Many people think that radiometric dating has proved the Earth is millions of years old.

That’s understandable, given the image that surrounds the method. Even the way dates are reported (e.g. 200.4 ± 3.2 million years) gives the impression that the method is precise and reliable (box below). However, although we can measure many things about a rock, we cannot directly measure its age.

For example, we can measure its mass, its volume, its colour, the minerals in it, their size and the way they are arranged. We can crush the rock and measure its chemical composition and the radioactive elements it contains. But we do not have an instrument that directly measures age.

No matter what the radiometric date turned out to be, our geologist would always be able to ‘interpret’ it. Before we can calculate the age of a rock from its measured chemical composition, we must assume what radioactive elements were in the rock when it formed. And then, depending on the assumptions we make, we can obtain any date we like. It may be surprising to learn that evolutionary geologists themselves will not accept a radiometric date unless they think it is correct—i.e.

it matches what they already believe on other grounds. It is one thing to calculate a date. It is another thing to understand what it means. So, how do geologists know how to interpret their radiometric dates and what the ‘correct’ date should be?

Field relationships A geologist works out the relative age of a rock by carefully studying where the rock is found in the field. The field relationships, as they are called, are of primary importance and all radiometric dates are evaluated against them.

For example, a geologist may examine a cutting where the rocks appear as shown in Figure 1. Here he can see that some curved sedimentary rocks have been cut vertically by a sheet of volcanic rock called a dyke. It is clear that the sedimentary rock was deposited and folded before the dyke was squeezed into place. Figure 1 Figure 2. Cross-section By looking at other outcrops in the area, our geologist is able to draw a geological map which records how the rocks are related to each other in the field.

From the mapped field relationships, it is a simple matter to work out a geological cross-section and the relative timing of the geologic events. His geological cross-section may look something like Figure 2. Clearly, Sedimentary Rocks A were deposited and deformed before the Volcanic Dyke intruded them. These were then eroded and Sedimentary Rocks B were deposited.

The geologist may have found some fossils in Sedimentary Rocks A and discovered that they are similar to fossils found in some other rocks in the region. He assumes therefore that Sedimentary Rocks A are the same age as the other rocks in the region, which have already been dated by other geologists. In the same way, by identifying fossils, he may have related Sedimentary Rocks B with some other rocks. Creationists would generally agree with the above methods and use them in their geological work.

From his research, our evolutionary geologist may have discovered that other geologists believe that Sedimentary Rocks A are 200 million years old and Sedimentary Rocks B are 30 million years old. Thus, he already ‘knows’ that the igneous dyke must be younger than 200 million years and older than 30 million years. (Creationists do not agree with these ages of millions of years because of the assumptions they are based on.

) Because of his interest in the volcanic dyke, he collects a sample, being careful to select rock that looks fresh and unaltered. On his return, he sends his sample to the laboratory for dating, and after a few weeks receives the lab report. The only foolproof method for determining the age of something is based on eyewitness reports and a written record.

Let us imagine that the date reported by the lab was 150.7 ± 2.8 million years. Our geologist would be very happy with this result. He would say that the date represents the time when the volcanic lava solidified.

Such an interpretation fits nicely into the range of what he already believes the age to be. In fact, he would have been equally happy with any date a bit less than 200 million years or a bit more than 30 million years.

They would all have fitted nicely into the field relationships that he had observed and his interpretation of them. The field relationships are generally broad, and a wide range of ‘dates’ can be interpreted as the time when the lava solidified. What would our geologist have thought if the date from the lab had been greater than 200 million years, say 350.5 ± 4.3 million years? Would he have concluded that the fossil date for the sediments was wrong?

Not likely. Would he have thought that the radiometric dating method was flawed? No. Instead of questioning the method, he would say that the radiometric date was not recording the time that the rock solidified. He may suggest that the rock contained crystals (called xenocrysts) that formed long before the rock solidified and that these crystals gave an older date. He may suggest that some other very old material had contaminated the lava as it passed through the earth.

Or he may suggest that the result was due to a characteristic of the lava—that the dyke had inherited an old ‘age’. The error is not the real error The convention for reporting dates (e.g. 200.4 ± 3.2 million years) implies that the calculated date of 200.4 million years is accurate to plus or minus 3.2 million years.

In other words, the age should lie between 197.2 million years and 203.6 million years. However, this error is not the real error on the date. It relates only to the accuracy of the measuring equipment in the laboratory. Even different samples of rock collected from the same outcrop would give a larger scatter of results.

And, of course, the reported error ignores the huge uncertainties in the assumptions behind the ‘age’ calculation. These include the assumption that decay rates have never changed. In fact, decay rates have been increased in the laboratory by factors of billions of times. Creationist physicists point to several lines of evidence that decay rates have been faster in the past, and propose a pulse of accelerated decay during Creation Week, and possibly a smaller pulse during the Flood year.

References • Woodmorappe, J., , TJ 15(2):4–6, 2001. . • Vardiman, L., Snelling, A.A. and Chaffin, E.F., Radioisotopes and the age of the Earth, Institute for Creation Research, El Cajon, California and Creation Research Society, St.

Joseph, Missouri, USA, 2000. Text is available at icr.org/rate . What would our geologist think if the date from the lab were less than 30 million years, say 10.1 ± 1.8 million years? No problem. Would he query the dating method, the chronometer?

No. He would again say that the calculated age did not represent the time when the rock solidified. He may suggest that some of the chemicals in the rock had been disturbed by groundwater or weathering.

Or he may decide that the rock had been affected by a localized heating event—one strong enough to disturb the chemicals, but not strong enough to be visible in the field. No matter what the radiometric date turned out to be, our geologist would always be able to ‘interpret’ it. He would simply change his assumptions about the history of the rock to explain the result in a plausible way. G. Wasserburg, who received the 1986 Crafoord Prize in Geosciences, said, ‘There are no bad chronometers, only bad interpretations of them!’ In fact, there is a whole range of standard explanations that geologists use to ‘interpret’ radiometric dating results.

Why use it? Someone may ask, ‘Why do geologists still use radiometric dating? Wouldn’t they have abandoned the method long ago if it was so unreliable?’ Just because the calculated results are not the true ages does not mean that the method is completely useless.

The dates calculated are based on the isotopic composition of the rock. And the composition is a characteristic of the molten lava from which the rock solidified. Therefore, rocks in the same area which give similar ‘dates’ are likely to have formed from the same lava at about the same time during the Flood.

So, although the assumptions behind the calculation are wrong and the dates are incorrect, there may be a pattern in the results that can help geologists understand the relationships between igneous rocks in a region.

Contrary to the impression that we are given, radiometric dating does not prove that the Earth is millions of years old. The vast age has simply been assumed.

The calculated radiometric ‘ages’ depend on the assumptions that are made. The results are only accepted if they agree with what is already believed. The only foolproof method for determining the age of something is based on eyewitness reports and a written record. We have both in the Bible. And that is why creationists use the historical evidence in the Bible to constrain their interpretations of the geological evidence.

What if the rock ages are not ‘known’ in advance—does radio-dating give coherent results? Recently, I conducted a geological field trip in the Townsville area, North Queensland. A geological guidebook, prepared by two geologists, was available from a government department. The guidebook’s appendix explains ‘geological time and the ages of rocks.’ It describes how geologists use field relationships to determine the relative ages of rocks. It also says that the ‘actual’ ages are measured by radiometric dating—an expensive technique performed in modern laboratories.

The guide describes a number of radiometric methods and states that for ‘suitable specimens the errors involved in radiometric dating usually amount to several percent of the age result. Thus … a result of two hundred million years is expected to be quite close (within, say, 4 million) to the true age.’ Photo by Phil Peachey Castle Hill (Townsville, Queensland, Australia) This gives the impression that radiometric dating is very precise and very reliable—the impression generally held by the public.

However, the appendix concludes with this qualification: ‘Also, the relative ages [of the radiometric dating results] must always be consistent with the geological evidence. … if a contradiction occurs, then the cause of the error needs to be established or the radiometric results are unacceptable’. This is exactly what our main article explains.

Radiometric dates are only accepted if they agree with what geologists already believe the age should be. Townsville geology is dominated by a number of prominent granitic mountains and hills.

However, these are isolated from each other, and the area lacks significant sedimentary strata. We therefore cannot determine the field relationships and thus cannot be sure which hills are older and which are younger. In fact, the constraints on the ages are such that there is a very large range possible. We would expect that radiometric dating, being allegedly so ‘accurate,’ would rescue the situation and provide exact ages for each of these hills. Apparently, this is not so.

Concerning the basement volcanic rocks in the area, the guidebook says, ‘Their exact age remains uncertain.’ About Frederick Peak, a rhyolite ring dyke in the area, it says, ‘Their age of emplacement is not certain.’ And for Castle Hill, a prominent feature in the city of Townsville, the guidebook says, ‘The age of the granite is unconfirmed.’ No doubt, radiometric dating has been carried out and precise ‘dates’ have been obtained.

It seems they have not been accepted because they were not meaningful. Reference • Trezise, D.L. and Stephenson, P.J., Rocks and landscapes of the Townsville district, Department of Resource Industries, Queensland, 1990. . References and notes • In addition to other unprovable assumptions, e.g. that the decay rate has never changed. . • Evolutionary geologists believe that the rocks are millions of years old because they assume they were formed very slowly.

They have worked out their geologic timescale based on this assumption. This timescale deliberately ignores the catastrophic effects of the Biblical Flood, which deposited the rocks very quickly.

. • This argument was used against creationist work that exposed problems with radiometric dating. Laboratory tests on rock formed from the 1980 eruption of Mt St Helens gave ‘ages’ of millions of years. Critics claimed that ‘old’ crystals contained in the rock contaminated the result.

However, careful measurements by Dr Steve Austin showed this criticism to be wrong. See Swenson, K., , Creation 23(3):23–25, 2001. . • This argument was used against creationist work done on a piece of wood found in sandstone near Sydney, Australia, that was supposed to be 230 million years old.

Critics claimed that the carbon-14 results were ‘too young’ because the wood had been contaminated by weathering. However, careful measurements of the carbon-13 isotope refuted this criticism.

See Snelling, A.A., , Creation 21(3):39–41, 1999. . • Wasserburg, G.J., Isotopic abundances: inferences on solar system and planetary evolution, Earth and Planetary Sciences Letters 86:129–173, 150, 1987.

. (Article available in and .) This excellent new resource contains 40 articles taken from the last 40 years of Creation magazine (with some updated, as necessary), covering a wide range of origin-topics—all bound together in a beautiful, hard-cover package.

128 brilliantly-illustrated pages packed with real-world evidence for biblical creation. While reading this article I could not help but think of the scientists who use this dating method to confirm their already held beliefs are like marksmen archers who shoot an arrow then go paint the bulls eye around it.

I can just hear the congrats as they pat each other on the back and comment, "wow, look at that, you've hit another bulls eye!" BTW, Great article and don't mean to be negative but, R.M.

(you called him Richard) did have a valid point which you did not adequately respond to. I had an atheist ask me a similar question that if science disproved my belief in God would I change my mind?

One could conclude that truth is false but that does not make the false true. I agree with you we/you are not being hypocritical, but I also agree with him that it appears as though we are. It's a great method for anyone who wishes to discredit creationists beliefs; or, at least it would be if it was not so discredited. Great article Dr. Walker! The perspective you present of "depending on the assumptions we make, we can obtain any date we like", certainly seems to match the data. What is unsettling is that some creationist geologists, e.g.

Dr. Snelling, say that if the dates are scaled and also adjusted for the type of radiometric test, creationists could use the dates. That view is also presented in a compelling fashion. The two views seem to be irreconcilable, but I'm not certain about it. Lots of radio-isotope dates are not reported, but are sitting in the researchers' files waiting for time to figure out what is going on with them.

However, there are lots and lots of dates that are reported but you would not be aware of the problems unless you know how to read the papers, and unless you refer to other papers that deal with the same topic. Read the above article again because it explains how all the results are interpreted such that they are consistent with the story the researcher wants to present. Search creation.com for "the dating game mungo" and "Radioactive dating anomalies" for two articles that show how the numbers are interpreted.

Dear CMI - The subtitle of this article states that “Long-age geologists will not accept a radiometric date unless it matches their pre-existing expectations.” This is a direct imputation of widespread scientific malfeasance on the part of professional geologists. Yet we read on your website (and on many other creationist sites) the following (taken from your ‘Statement of Faith'): “By definition, no apparent, perceived or claimed evidence in any field, including history and chronology, can be valid if it contradicts the Scriptural record.” How is this different from the attitude that you criticize mainstream geologists for adopting?

Is there a “mote in thy brother’s eye” or “a beam … in thine own eye? Oh Richard, I know that you know how the scientific paradigm affects interpretations and research outcomes. Long-age geologists are committed to the long-age paradigm, which assumes naturalism. This article makes the point that, contrary to the impression we are given, the radio-isotope dates are not a scientific fact but are interpretations driven by the paradigm.

Understanding that liberates people to be able to look at the world from a different perspective. We have clearly set out the worldview within which we are working: we believe the Bible is the true revelation of the Creator God who made this world. That is not hypocrisy, but being open and up-front about where we are coming from. Privacy & Content Ownership • Comments become the property of Creation Ministries International upon submission and may be edited for brevity and clarity. • CMI may choose not to publish your comment depending on how well it fits the guidelines outlined above.

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But we cannot assume responsibility for, nor be taken as endorsing in any way, any other content or links on any such site.

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best radiometric dating is based on answers

As been already pointed out, Zealandia can be put together with South America: There is beauty in simplicity: Zealandia/South America rende... The best explanation for the observed relations is Earth's rapid expansion since the Pangea break up. So I am asking, because according to the expansion, the fossils should be younger than we think today, maybe not, but it would be more elegant to link the evolution directly with the expansion.

When we understand dating methods as being based on models (i.e. representations of some portions of reality), we shall ask ourselves whether those models are linear deterministic, non-linear deterministic, stochastic, or hybrid.

I am under the impression that often archaeologists expect dating methods to behave in a linear deterministic way, while they most often behave stochastically or in a hybrid way. It looks like this misconception may be particularly problematic when combinig the results of different dating methods (scientific, archaeological, historical) to obtain a general...

It is noticed while going through the modern day papers except a few structural geological and sedimentological papers that the general approach is to collect samples and take as less field traverse as possible and analysed after coming back to lab and interpret in a smart sophisticated way and publish.

In fact may be field visit is the purpose to collect samples. The small domain field based papers are not suitable for global readers but after including all small domain one can talk about larger area, perhaps entire cratons.

Other than mineral identification and some petrological works... “Impressive comments!! Truly written factual information. However sir, Classical field work s related contributions are not saturated. There are a lot of things must be published apart from mapping. For example I have seen so many theoritical papers on felsic volcanics but after reading the paper as well as books we face difficulties in a different context to practically recognize the features characteristics of same in the field.

I mean there should be a parallel approach regarding field geology. It's applicable to any of the branches in geology which can be visualize in a simplified way....” l am dealing with dating of anorthosite using U-Pb zircon LA ICP-MS.

Anorthosite is a rock type of the mafic-ultramafic succession, which is composed of pyroxenite (bottom), olivine-, and oxyhornblende gabbros, then anorthosite, and porphyritic quartz-diorite (top). Anorthosite is commonly traversed by felsite veinlets (1-5 cm thick). It intrudes the surrounding volcanics, older granitoids (615-735 Ma) but are intruded by the younger granites (610-550 Ma).

Petrographically, anorthosite is composed totally of plagioclase megacrysts with subordinate interstitial amount of augite, enstatite,... “Dear. Prof. Eliwa According to your information above, You have two probabilities as I think: 1- The core in abnormal core-rim structured zircon is xenocryst from surrounding rocks or older rocks ..... because the core age is nearly close to age of older granitoids. 2- The core itself represents the age of anorthosite, and the rims and homogeneous zircons represent the hydrothermal/recrystallized growth and zircon (It refers to zircon crystallized from, or altered by an aqueous fluid).

It may be formed as a result of heating of granitic magma intrusion or hydrothermal solutions triggered...” I am looking at correcting TLS Intensity for range (distance) and incidence angle error. I have found a many sources for this that have used commercially available reference targets, however I want to know if it is possible to perform the correction without the calibration target?

In order to perform the correction I need values for receiver power, transmitted power, receiver aperture, range, transmitter beam width, and backscatter cross section. I am unsure as to how to work out the values for these parameters. Are they worked out with the used of the calibration target?

Or are they... “I did a fair bit of this over the years, and yes vitrinite reflectence does not help much with the timing of maximum burial but when combined with fission track dating and track length analysis and using that information to create a burial history plot you are on your way to getting to a Tt path. Please try both forward models and inverse model to best understand the thermal history.” “Lets assume you have a time series of data x1, x2, x3 ....and you want to compute the 2-dimensional projection of the attractor for this series It can be one of a point, a limit cycle or strange (fractal) attractor.

It follows from the Ruelle-Takens theorem that if you plot pairs of points {x1,x2}, {x3,x4} {x5,x6} ....etc then the resultant plot will converge to a 2-dimensional projection of the attractor. This result was one of the main insights of Chaos theory which applies when the attractor is strange/fractal giving rise to an apparently random time series from non random...” I've carbon-dated a number of micro charcoal samples collected from soil in hopes of determining when the most recent fire event occurred.

However, upon receiving the result back from the lab, they explained that a definitive date for the charcoal could not be determined because of the Suess Effect. In other words, the charcoal was dated between 1650-1950 and due to the highly variable atmospheric concentrations of C13/C14 (because of combustion of fossil fuels), the age could not be determined beyond + or - ca. 150 years. Is it possible to correct for the suess effect somehow to narrow...

I would be interested in the specifics. What did you do and when? How did your effort turn out? Were there independent means of cross checking your derived dates? What did it cost? Was it a destructive technique? Did the analyst have to visit the site where you acquired the rock art or artifacts?

Has anyone tried to use a dating technique for desert varnish on ancient flaked stone artifacts? I am only aware of one published study in Argentina. That one seemed interesting and rather helpful. “Hi All, Thank you very much. These are really helpful. I just want to understand a published data better. I am not going to do some Rb-Sr dating of sericite. I have done some Ar/Ar dating of muscovite and sericite. They are products of hydrothermal alteration at the Jiaodong gold deposits, eastern China.

Have a good day. Kind regards, Liang” “O18 cellulose extracted from wood is the most used to study climate variations (paleoclimate). Tree rings Such parameters as tree ring width and wood density-have long-been used as climate proxies By Many investigators. In the last Decades, Numerous studies-have Demonstrated the potential of carbon stable isotope ratios in tree rings as proxy indicators of past climatic condition.But Anyhow, I wonder if that signal will be strong (and long-lasting) enough to track trophic interactions.” Hi!

I`m working with archaeological isotope data and I wanted to use the siarelicit function to introduce some priors.

These priors are proportions I obtained by reading the literature of the archaeological site of how much of each food my consumers would have eaten. The SIAR manual says I have to run siarmcmcdirichletv4 and then use the siarelicit(model1) function. The proportions must sum to 1 and the SIAR V4 Ecologist`s guide says that the first of it must be 0.7.

Is this right? There isn`t such a prevalence in the components of the diet I`m working with. Can I still use this function... “The most readily applicable method for this approach would be Ar/Ar dating- which will work well in this age framework. However, this would require the coals are associated with a sedimentary succession containing near coeval volcanic ash. This is the dating approach that has been employed in determining the age of Carboniferous coals in the UK.

Many terrestrial lacustrine and swamp-type sedimentary successions do contain suitable ashes - but identification of such horizons requires careful logging. If you can find such materials then the opportunity arises for separation of suitable...” Does anyone know any papers or unpublished report/s on the effect of marine water on the stable isotope signature of sub-fossil wood.

I'm wanting to start an isotopic project on sub-fossil wood removed from ancient beach deposits. And my student is concerned about the effects of marine water and bacteria on the stable isotope results.

Part 2: How can i derive equations in radioactive decay? Is there a way to estimate mathematically the "geologic time" t (in Nabil Ayuob's post) of a Uranium-Thorium-bearing mineral or the time when the mineral was formed?

The number of atoms of Uranium and Thorium at the time when the mineral was formed, No and number of atoms of their stable daughter NPb are both unknown. It is assumed that the system is already in secular equilibrium. It is similar to what Poshitha Dabare said on radiometric dating but using the uranium, actinium and thorium decay series - U/Pb ratio or Th/Pb ratio or...

I've had 3 "sub-samples" of a sediment core analyzed to ascertain the 10Be concentration levels. The sediment was taken from a closed basin - centripetal drainage pattern.

The results indicate that I have a trend from top to bottom, but no age range was offered to me from the lab who ran the analysis. I've been looking for papers regarding this dating method, but I'm hoping that someone on this website maybe able to narrow down my search scope. If you need further information from me - please let me know. “Hello Janet, I have used 26Al/10Be in a couple projects and am familiar with various applications, some questions about your project I hope will help you with your question...

Was the 10Be you measured 'in-situ', meaning was it formed inside a quartz crystal lattice during exposure near the surface (during erosion/deposition)? Or was the isotope 'meteoric', meaning the 10Be is formed in the atmosphere?

Depending on how the sample prep and analyses were conducted you will be able to accomplish different task with your data. I specialize in the 'in situ' technique.

I don't have experience...” “Hello Alwynne, there is no single generally accepted definition, at which time or which state of mineralisation an organism (or a group of them) can be called "fossil". The two most common ones used by palaeontologists and geologists are those: With definition over the term "petrification", but with biomineralization (e.g. recent stromatolites) and early precipitation of Minerals (phospates within seconds after death, for example the fossil lagerstaetten of the Cretaceous Araripe Basin in Brazil, the Orsten in Scandinavia, but also only 100-year-old completley mineralized fishes from...” “Hi Jos, Yes, you should use Marine13 and apply the appropriate local/regional deltaR value (see 14CHRONO Marine Reservoir Database at http://calib.qub.ac.uk/marine/).

Although the species appears to be a suspension-feeder, I note that it is densest in in-shore zones (http://www.reservebaiedesaintbrieuc.com/IMG/pdf/publication/etudes_scientifiques/Ponsero&al-2009-Cockle.pdf) so may be influences by terrestrial run-off or restricted in-shore/embayment circulation patterns. See the following for an interesting case study of the potential differences in bivalves living in different zones and...” “I shall grateful if you can send me two or three planchet holders to my address given below: Dr.

V. Kannan Scientific Consultant National Centre for Sustainable Coastal Management Government of India Anna University Campus Guindy, Chennai-600025 Tamilnadu State India At present I am planning to determine Po-210 in surface sediment sample in India.

Your device will be helpful in alpha counting using alpha spectrometry. v.kannan” “I would suggest you provide more information about the technique you are using (LA, SIMS), what mass spec you have (Quad, MC?), and how you are processing (what software?). CommonPb is unlikely to be an issue within the zircons as both those standards are very low in common Pb (that is why they are standards), and should get good ages by SIMS or LA-ICPMS.

And so the only way you are going to introduce common Pb is through your preparation, and hopefully you are doing that carefully. Also be wary of the Anderson correction method until you know more about your sources of error! It...” Many disasters like volcanic eruptions or major floods, or even earthquakes took place along the recent periods on the geologic time scale, along with that, speleothems inside caves, and rings of old trees were recording those event synchronized with them, looking for any research that has touched upon or approached this area of science.

“Hi Carlo, about 1 year later I have to revise my answer to this question. My answer now would be Yes, I know a lab in Germany doing it by U-Pb LA-SFICP-MS. Results/data look very promising and I have to admit that my statment last year was a bit too pessimistic. If you are still interested in dating of your dolomite and calcite cements, please contact me but you might have found already a way/lab.... regards Axel ” “Good evening: For some discussion of this question with respect to radiocarbon dating (one form of radiometric dating) and organic materials, see the following page: Radiocarbon Dating and Bomb Carbon http://www.radiocarbon.com/carbon-dating-bomb-carbon.htm and the following recent article and references therein: Bomb-curve radiocarbon measurement of recent biologic tissues and applications to wildlife forensics and stable isotope (paleo)ecology http://www.pnas.org/content/early/2013/06/26/1302226110 A good place to look for more articles on this topic is the journal "Radiocarbon" if...” “Hi Thomas, I also suggest my lab, the CEREGE in Aix-en-Provence, France.

For exposure dating, you can contact Pr Didier Bourlès (bourles@cerege.fr) the head of our team or Dr Régis Braucher (braucher@cerege.fr). We organize also the AMS 13th conference at the end of this summer 24-29 August 2014. http://ams13.cerege.fr. ” “Hi Ozgur! I'm not sure that using cosmogenic dating will help you very much with Pliocene or older deposits in Europe. Snow cover is a large uncertainity, as is any calculation of long-term production rates.

When I have been out with cosmogenic people they look for the biggest boulders they can and go right to the top of them to sample. John Stone, Robert Ackert, and Mark Kurz may have more answers for you in their papers. Consider looking at the CRONUS site at this URL (although it needs an updated publication page) or this URL for the Purdue PRIME lab (extensive publication list)....”


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