EvC Forum: Information

The Grand Canyon as a Creationist Clock By Ryan McGillivray When asked to imagine the biggest, deepest, longest canyon one can imagine, an image of the Grand Canyon will often pop into a person’s mind. The Grand Canyon is a site of almost unfathomable grandeur, which inspires awe in anyone who sees it. Lately, however, the canyon has also inspired controversy, specifically over its origins. It is generally held by the scientific community that the Grand Canyon formed by the slow erosion of the Colorado River over millions of years. Steve Austin, however, has proposed an entirely different theory on the age and formation of the canyon and wrote a book explaining his theories titled Grand Canyon: Austin believes that the canyon was formed extremely rapidly during the period immediately following the global flood of Noah in the biblical book of Genesis.

Sm nd radiometrisk datering

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Sean Fox, Carleton College Reuse:

Nd Sm Nd Nd Possible dating applications • Cooling of basic intrusions • Usage analogous to the Sm–Nd method • Shorter half life and higher Lu/Hf ratios of common rocks and minerals result in greater variability of the Hf isotopic composition (= advantage).

The two elements are joined in a parent—daughter relationship by the alpha decay of Sm to Nd with a half-life of 1. Some of the Sm may itself have originally been produced through alpha-decay from Gd , which has a half-life of 1. To find the date at which a rock or group of rocks formed one can use the method of isochron dating. From the slope of the “isochron” line through these points the date of formation can be determined. Alternatively, one can assume that the material formed from mantle material which was following the same path of evolution of these ratios as chondrites , and then again the time of formation can be calculated see The CHUR model.

Samarium is accommodated more easily into mafic minerals, so a mafic rock which crystallises mafic minerals will concentrate neodymium in the melt phase relative to samarium. Thus, as a melt undergoes fractional crystallization from a mafic to a more felsic composition, the abundance of Sm and Nd changes, as does the ratio between Sm and Nd.

The importance of this process is apparent in modeling the age of continental crust formation. The CHUR model[ edit ] Through the analysis of isotopic compositions of neodymium, DePaolo and Wasserburg [2] discovered that terrestrial igneous rocks at the time of their formation from melts closely followed the ” chondritic uniform reservoir ” or “chondritic unifractionated reservoir” CHUR line — the way the Nd:

Historical Geology/Ar

Geologists obtain estimates for the passage of time from two distinctly different sources. So-called ‘absolute’ radiometric dates are derived from the decay rates of various radioactive isotopes in igneous volcanic or molten rocks. Although the underlying theoretical basis for ‘absolute’ or radiometric dating appears to be sound, there are some troubling issues arising from its application that are yet to be resolved.

For example, a recent careful study based on zircon crystals in basalts lavas from cores taken nearest the Mid-Atlantic Ridge yielded uranium-lead dates ranging from million to 1. The authors had no coherent explanation for the anomalous dates.

isotopic method was implanted at the Geochronology Laboratory of the University of Brasília. The Sm-Nd separation methodology is basically that described in Richardet .

The isochron method Many radioactive dating methods are based on minute additions of daughter products to a rock or mineral in which a considerable amount of daughter-type isotopes already exists. These isotopes did not come from radioactive decay in the system but rather formed during the original creation of the elements. In this case, it is a big advantage to present the data in a form in which the abundance of both the parent and daughter isotopes are given with respect to the abundance of the initial background daughter.

The incremental additions of the daughter type can then be viewed in proportion to the abundance of parent atoms. In mathematical terms this is achieved as follows. This term, shown in Figure 1, is called the initial ratio.

The Age of the Earth, G. Brent Dalrymple

In the context of dating works of art, the relevant techniques are radiocarbon dating, thermoluminescence dating and dendrochronology. Radiocarbon dating is possible because of the continuous formation of the radioactive isotope of carbon carbon that occurs in the upper atmosphere when neutrons produced by cosmic rays interact with atmospheric nitrogen atoms. Carbon combines with oxygen to form radioactive carbon dioxide, which then mixes throughout the atmosphere, dissolves in the oceans and, via the photosynthesis process and the food chain, enters all plant and animal life.

Since carbon is produced by cosmic ray neutrons at a more or less constant rate and, at the same time, is lost by radioactive decay, an equilibrium concentration of carbon is established: All living plants and animals therefore contain this equilibrium concentration of carbon

Mar 27,  · The Sm-Nd method is even more reliable than the Rb-Sr method of dating rocks and minerals, because samarium and neodymium are less mobile than rubidium and strontium. The isotopic evolution of neodymium in the Earth is described by comparison with stony meteorites.

Sm-nd dating method Sm-nd dating method In nature, however, each mineral in the rock is likely to have a different amount of 87 Rb. Since Ar is a noble gas, it can escape from a magma or liquid easily, and it is thus assumed that no 40 Ar is present initially. From the Pb-Pb isochron how to take a good dating profile pic 11 we can make some arguments about meteorites. Zircon can also survive metamorphism. This gives us only a minimum age of the Earth. The answer is about 6 billion years.

Elements like K, U, Th, and Rb occur in quantities large enough to release a substantial amount of heat through radioactive decay. Since the mineral troilite contains no U, all of the Pb present in the troilite is the Pb originally present, and none of it has been produced by U decay. Radiocarbon dates are obtained from such datings method as bones, teeth, charcoal, fossilized wood, and shells. If complete loss of Ar occurs during metamorphism, then the date is that of the metamorphic event.

Such trapped Ar is not problematical when the age of the rock is in hundreds of millions of years. Radioactive decay is described in terms of the probability that a constituent particle of the nucleus of an atom will escape through the potential Energy barrier which bonds them to the nucleus. Such a chord is called a discordia. Thus, if we start out with 1 gram of the parent isotope, after the dating method of 1 half-life there will be 0.

Rubidium

Slowly and painstakingly, geologists have assembled this record into the generalized geologic time scale shown in Figure 1. This was done by observing the relative age sequence of rock units in a given area and determining, from stratigraphic relations, which rock units are younger, which are older, and what assemblages of fossils are contained in each unit. Using fossils to correlate from area to area, geologists have been able to work out a relative worldwide order of rock formations and to divide the rock record and geologic time into the eras, periods, and epochs shown in Figure 1.

The last modification to the geologic time scale of Figure 1 was in the s, before radiometric dating was fully developed, when the Oligocene Epoch was inserted between the Eocene and the Miocene. Although early stratigraphers could determine the relative order of rock units and fossils, they could only estimate the lengths of time involved by observing the rates of present geologic processes and comparing the rocks produced by those processes with those preserved in the stratigraphic record.

We are also grateful to him for a thoughtful E. Aliberti, Sm-Nd dating of multiple garnet growth O critical review of the manuscript, which substan- events in an arc-continent collision zone, northwestern tially improved the quality and clarity of the pa- U.S. Cordillera, Contrib. Mineral.

A Variety of Approaches p18 “Not until the Enlightenment did observation and secular reasoning become widely accepted as an alternative to the Christian interpretation of nature, and modern science was born. But the habits of centuries were difficult to overcome. To be sure, his view is skewed by having dealt with the likes of Morris and Gish so much, but there is still no excuse for being this ignorant of the role that Christian faith played in the beginning and advance of modern science.

The finding of sea shells high in the mountains was taken as evidence that seas had dropped over the ages – in print Based on an extrapolation of the amount of sea level drop, ft or ” per century gave 2. Notable for usig physical observations to project age. Russell, about 4 billion in , range billion years. Ch 3 Modern Radiometric Methods. Other 52 are short-lived daughter products isotopes created in the laboratory. Except in nuclear reactions, such energies are generally unavailable in natural processes such as those that form, change, and destroy rocks on the Earth and in the Solar System.

Decay rate in 7Be metal 0. Maximum difference found between two Be compounds is 0. Also measurable pressure effect on decay of BeO. Uses the term “isotropic homogenization”.

PPT

Reference to a case where the given method did not work This is perhaps the most common objection of all. Creationists point to instances where a given method produced a result that is clearly wrong, and then argue that therefore all such dates may be ignored. Such an argument fails on two counts: First, an instance where a method fails to work does not imply that it does not ever work.

The question is not whether there are “undatable” objects, but rather whether or not all objects cannot be dated by a given method.

The Encyclopedia of Scientific Dating Methods has been selected to receive the GSIS Mary B. Ansari Best Reference Work Award. J.W. Jack Rink and Jeroen W. Thompson are the editors of this reference work published by Springer in

Using modern equipment and instruments, the technicians have made considerable progress in the development of innovative analytical methods and new technical investigations, which have, in turn, been widely applied by scientists around the world. The method of in situ simultaneous determination of trace elements i. In situ Sr-Nd isotopic analysis of single minerals, such as plagioclase, calcite, titanite, apatite, perovskite and monazite, give the MC-ICPMS laboratory unique abilities. Eudialyte is the only mineral that may be used for in situ simultaneous determination of trace elements i.

Moreover, this method may also be used for the dating of accessory minerals of a younger age in thin sections without external standardization. This technique has been applied to fine-grained accessory minerals found in meteorite. The possibility of young baddeleyite dating by SIMS has become a reality, and therefore, the technical problems of basic and ultrabasic rock dating have been solved.

The study of reference materials for in situ isotopic ratio measurement Reference materials form the basis of in situ analysis. As analysis and testing in China are always carried out based on international reference materials, Chinese geologists have depended on international reference materials for many years. This situation has become one of the main obstacles to the development of in situ techniques. Penglai Zircon and M Zircon have been used as the first working references for Hf-O isotopes in China and Li isotopes in the world, respectively.

This laboratory continuously makes breakthroughs in reference materials for isotope microanalysis in China. Analytical methods of stable isotopes The institute has established oxygen isotopic analyses methods for zircon, apatite, quartz and olivine, as well as a lithium isotopic analysis method for olivine. In situ oxygen isotopic analyses of olivine may be performed in thin sections, which provides important information concerning mantle metasomatism.

PPT

Methods of Dating the Age of Meteorites Meteorites are among the oldest objects we know about – formed about 4. But how do scientists know this? This article describes the principles and methods used to make that determination. There are well-known methods of finding the ages of some natural objects. Trees undergo spurts in growth in the spring and summer months while becoming somewhat dormant in the fall and winter months.

When a tree is cut down, these periods are exhibited in a cross section of the trunk in the form of rings.

Sm-Nd Ages of Ferroan Anorthosites: Seven FANs have been age dated by the Sm-Nd method breccia(Fig. 1): (clast 3A – [13]); has two distinct.

Radioactive decay[ edit ] Example of a radioactive decay chain from lead Pb to lead Pb. The final decay product, lead Pb , is stable and can no longer undergo spontaneous radioactive decay. All ordinary matter is made up of combinations of chemical elements , each with its own atomic number , indicating the number of protons in the atomic nucleus. Additionally, elements may exist in different isotopes , with each isotope of an element differing in the number of neutrons in the nucleus.

A particular isotope of a particular element is called a nuclide. Some nuclides are inherently unstable. That is, at some point in time, an atom of such a nuclide will undergo radioactive decay and spontaneously transform into a different nuclide. This transformation may be accomplished in a number of different ways, including alpha decay emission of alpha particles and beta decay electron emission, positron emission, or electron capture.

Another possibility is spontaneous fission into two or more nuclides. While the moment in time at which a particular nucleus decays is unpredictable, a collection of atoms of a radioactive nuclide decays exponentially at a rate described by a parameter known as the half-life , usually given in units of years when discussing dating techniques. After one half-life has elapsed, one half of the atoms of the nuclide in question will have decayed into a “daughter” nuclide or decay product.

In many cases, the daughter nuclide itself is radioactive, resulting in a decay chain , eventually ending with the formation of a stable nonradioactive daughter nuclide; each step in such a chain is characterized by a distinct half-life. In these cases, usually the half-life of interest in radiometric dating is the longest one in the chain, which is the rate-limiting factor in the ultimate transformation of the radioactive nuclide into its stable daughter.

Interference figures


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