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In rubidium-strontium dating, micas exclude strontium when they form but accept much rubidium. In uranium-lead U-Pb dating of zircon, the zircon is found to exclude initial lead…. The radioactive decay scheme involving the breakdown of potassium of mass 40 40 K to argon gas of mass 40 40 Ar formed the basis of the first widely used isotopic dating method.
Since radiogenic argon was first detected in by the American geophysicist…. Potassium—argon dating has made it possible to establish that the earliest remains of man and his artifacts in East Africa go back at least 2,, years, and probably further. Potassium-argon dating , for instance, can provide the age of a specimen by clocking the rate at which radioactive isotopes of these elements have decayed.
When radiometric methods cannot be applied, investigators may still ascribe a relative age to a fossil by relating it to the…. More About Potassium-argon dating 5 references found in Britannica articles Assorted References major reference In dating: Analysis of separated minerals In dating: Potassium—argon methods age determination of tektites In tektite: Chemistry and petrography of tektites archaeology In archaeology: Dating Homo erectus In Homo erectus: Help us improve this article!
Contact our editors with your feedback. You may find it helpful to search within the site to see how similar or related subjects are covered. So instead, the rocks surrounding the fossil is dated.
Their assumption that the fossil is the same age as the surrounding rock allows them to do this kind of data collecting. What they do is to take samples of the rock layers above and below where the fossil or specimen is located. Then these rock samples are dated. The researcher then assumes that the dates he or she gets are good minimum and maximum ages for the fossil.
The kinds of rock that this process is thought to work best with is various kinds of igneous rocks, volcanic rock and ash. Biotite and hornblende give the best dates from an evolutionary perspective. Hornblende give the best date that agree with the evolutionary time scale, but biotite is much more abundant and can keep it's Argon under various weathering conditions.
Sanidine, anorthoclase, plagioclase, leucite, nepheline, muscovite, phlogopite, and lepidolite. Whole rock basalt lava and some report that ash can also be used. The only sedimentary rock which can be dated is glauconite, but the results are not always considered reliable by evolutionists. Potassium 40 K 40 is one of three isotopes of Potassium K that is found in the earth's crust see the graphic to the left or above. Both Potassium 39 and 41 are stable and accounts for Potassium 40, on the other hand, only accounts for 0.
K 40 is also radioactive, because it has odd numbers of both protons and neutrons in its nucleus. K 40 has a half-life of 1. If a K 40 atom degrades by beta decay then a Calcium 40 atom is produced. However, if the degradation is by either electron capture or positron decay, then Argon 40 is produced. The beta decay is a faster process. It would seem that Calcium 40 would be the better product atom to track since almost 10 times of it is produced over Ar However, there is a problem with Ca Ca 40 is an extremely abundant atom found in various minerals.
How would the Ca 40, that is naturally found in the rocks, be distinguished from the Calcium 40 that is produced by the breakdown of K 40? We would only want to measure the amount of Calcium 40 that is produced when K 40 is broken down, and not the natural Ca 40 in the rocks that would contaminate our measurements. This is a bad contamination problem so Ca 40 is not used in any dating calculations. On the other hand, Argon 40 has just the right characteristics that would seem to make the PotassiumArgon40 reaction useful to date various kinds of igneous rocks, volcanic rock and ash.
Hi, From my experiences described on this page, I know that Jesus is truly coming back to save us from this angry and destructive world. In addition, I have found, much to my delight, that science within the creationary paradigm, works! It is an exciting thing to explore our Biosphere from a different perspective than everyone else. Often new possibilities are realized when this fresh new perspective is explored. And when I see new explanations to phenomena that no one else sees, because I am working in a new paradigm , it is down right exciting!
Ar 40 is used for several reasons. First of all, Argon is inert. It does not chemically react with other elements at all. So Argon does not attach itself to the rock or any minerals in the rock. Secondly, Argon is usually a gas.
These features are thought to allow any naturally occurring Argon from contaminating our measurements of the Argon 40 that is being produced from the radioactive decay of K When volcanic material flows over the land, the naturally occurring Argon gas is driven off by the excess heat. When the rock is molten hot, it is more liquid in texture, allowing the Argon gas to escape.
If all the gas is driven off, then there should be no Argon left in the rock. Once the rock cools and hardens, it is considered to be a closed system, because any new Ar 40 that is produced by the breakdown of K40 is trapped inside the rock crystal and cannot get out. So the scientist assumes that he or she is able to measure only that Ar 40 which is produced from K 40 since the rock has cooled.
All the other Ar 40 was forced out of the rock by the heat. By forcing out the naturally occurring Ar 40, the clock of the dating mechanism is reset or set to zero. Later, when we start discussing the K-Ar dating technique from a Creationary perspective, we will see that this reseting of the clock is a major issue. The clock might not always be reset by the heat in the Rock.
There are other factors which might not allow the Argon to coming out of the rock as well. An interesting point to make is that the Potassium-Argon process does not date the age of the rock.
What it does, is to tell you how long ago the rock was reset, or set to zero. In addition, some rocks may have been reheated so that the clock was partially reset or fully reset at a later date. So if there are multiple heatings of the rock, the K-Ar dating process may give the researcher a number that is not what the researcher expects to find. Another issue is atmospheric Argon However, this contamination can easily be accounted for in the calculations.
Since Argon 40 exists in the atmosphere, there is a possibility that rock samples could be contaminated with atmospheric Argon. Because the atmospheric Argon is a mix of three different isotopes of Argon: Since there is more Ar than Ar, the amount of Ar is measured to determine the amount of atmospheric Argon that is inserted in the rock. So this factor can be used to estimate the amount of Argon 40 that has come into the rock via Atmospheric contamination.
In any kind of a historical science, assumptions have to be made in the assessing of historical dates. Because it is assumed that man, for example, has ascended over a long period of time, researchers would automatically want to lengthen the amount of time indicated by the artifacts uncovered in archeological digs. They are looking for answers that would fit their present model. I am not trying to say that they are falsifying their data. On the contrary they wouldn't need to falsify anything.
Historical data can be so inconclusive that a host of positions is possible from almost any set of data that is collected. Man is thought to have progressed through a long period of prehistory cave man's experience before some sort of civilization is started. Only after civilization begins can we begin to gather some sort of data from the discovery of the artifacts that are found Pieces of pottery, etc. The artifacts according to today's traditional thinking should be slowly progressing in complexity as it is thought that man is progressing in his abilities and ideas that he uses.
If man is thought to have progressed over long periods of time, even within the later civilization phase of his existence, than surely as the artifacts are recovered from archaeological sites, the theories and ideas developed will reflect the scientist's own original thinking. This is how science normally works. They normally work within a fairly well defined set of theories that have become a paradigm.
A paradigm is a theory that is so well accepted that no one seriously questions it. This way of doing science is most prominent when the evidence is fragmentary at best.
Only when specific data comes that either substantiates or falsifies the previously held assumption, can it be known if the thinking was originally correct. In any kind of a historical science, assumptions have to be made in the assessing of historical dates. Skinner, only 10 could be used. The ratio of K to total K is constant. I am also interested in the fact that pillow lava structures are found in these rocks which is an indication that the volcanic flow was formed underwater!
Assumptions throughout the scientific process are extremely important because they must hold the facts together. Only when specific data comes that either substantiates or falsifies the previously held assumption, can it be known if the thinking was originally correct.
Unfortunately, with fragmentary data, the artifact that might falsify a theory is extremely hard in coming or it could easily be overlooked. So the problem must be solved by a host of assumptions that will probably never be tested. There is also the danger that good data could be thrown out because it doesn't fit with established thinking.
For instance, I am told that there are sometimes found in the same level both "early" forms and "modern" forms of man. Because of what is considered to be an impossibility, the modern forms are assumed to have been examples of intrusions. The modern form is considered to have been buried much later in spite of the fact that the specimens are found in the same level.
The areas of science, which are the most successful, which the public notices, are the amazing discoveries in medicine, biology, space exploration, and the like.