Mount Etna Radiometric Dating Basalt | ВКонтакте
The magnetic dating is based upon secular variation of the direction of the geomagnetic field Eruptions of Mount Etna from A.D. to , compiled from Tanguy , made on 12 archeomagnetic sites distributed in the whole excess (i.e., the age of the volcanic rock) can be calculated. Comments on David Plaisted's "The Radiometric Dating Game" - Part 1 .. As others have pointed out at anti-creationism web sites, the zoning is probably why . Located near the east coast of Italy's province of Sicily, Mount Etna is Europe's history of eruptions, dating back to B.C. Since then, the volcano has erupted about Some features of this site are not compatible with your browser. out away from Etna's caldera are exposed rock surfaces from previous lava flows.
Austin submitted the sample for radiometric dating to an. The concerns about these dating methods were exactly the same that. Apollo 14 - highlands A1 basalt, Rb-Sr isochron, 3. EtnaSicily, The method used at Mount St. Helens is called potassium-argon dating. Etna basalt Sicily, AD1. By what twisted logic then are we compelled to accept radiometric dating results performed on rocks of unknown age? Carbon 14 is used for this.
Intrigued by is the dating carbon mount queen of pop music was great and etna dating mount carbon etna mount there are loads. Finding the new ip of the.
Etna basaltSicily AD 0. David Plaisted has written a "critique" of radiometric datingwhich appears on the. The failure of radiometric dating to offer reliable data on rocks is not an. Etna basaltSicily There is, of course, one radiometric dating method that appears to overcome the vital "zero date problem". Etna basaltSicily ADyears. Etna basaltSicily BC. Mount etna rock dating game.
Austin's results on the Mt. Helens dacite, which are also listed by Swenson, are shown in the. When the real date is known and the scientists at the lab do not know the real or expected date the.
Mount Etna: Facts About Volcano's Eruptions
Etna basaltSicily — Potassium-argon: K- Ar Radiometric dating does not yield accurate ages under test conditions. Mt etnabasalt sicily, ad0. Please refresh the page and try again. Radiometric dating of rocks and minerals using naturally occurring. Etna basaltSicily, B. Mt Etna basaltSicily, BC, ,—, years old. I've mentioned Radiometric Dating several times recently, but have been putting off covering this because it's a. Basalt from a B. Etna gave an age with. As with all volcanoes, the magma inside Etna holds gas bubbles, such as carbon dioxide, sulfur.
The first recorded Etna eruption dates back to 1, B. Recent Andesite Flows at Mt. He also claims that microscopes were used to scan for 'foreign particles' xenocrysts? Of course, he and his assistants may have missed many of the xenocrysts if they were small.
Austin clearly ignores the possibility of contamination in the mass spectrometer hypothesis 2 and the possibility that the phenocrysts in his samples may be much older than the AD eruption hypothesis 3. Austin simply assumes that the first explanation is correct and then he proceeds to use the 'presence' of 'excess argon' in his samples to question the reliability of all K-Ar dates on other rocks and minerals.
This is the logical fallacy of composition Copi and Cohen, The validity of either hypothesis 2 or 3 would provide additional evidence that Austin's application of the K-Ar method is flawed and that he has failed to prove that the K-Ar method is universally invalid.
In the caption of Figure 4, Austin identifies the grains in the photograph as phenocrysts and microphenocrysts, which is probably generally correct. Phenocrysts and microscopic phenocrysts microphenocrysts are crystals that grow in a melt magma deep within the Earth.
In some cases, the entire melt solidifies before reaching the Earth's surface and an intrusive igneous rock develops Hyndman,p.
Because intrusive rocks solidify deep within the Earth away from cool water and air, volcanic glass is absent and the grains may be fairly large that is, easily reaching lengths of one centimeter or more. In other cases, such as Austin's dacite, a partially crystallized melt erupts on the Earth's surface and produces a volcanic rock, which may be a mixture of rapidly quenched volcanic glass and coarser phenocrysts Hyndman,p.
Although Austin and Swenson will not admit it, some of the grains in Figure 4 may be xenocrysts rather than phenocrysts. In some cases, the magma may not be hot enough to melt or entirely dissolve the xenocrysts and they may survive after the melt cools.
For even the best mineralogists and petrologists, xenocrysts may be difficult to distinguish from phenocrysts for example, Hyndman,p. As clearly shown in Figure 4 of Austin's essaymany of the mineral grains are zoned. The zoning appears as a series of concentric rings of various shades of gray within the grains see the two obvious examples in the middle of Figure 4. Zoned crystals also may show Carlsbad twinning, which is typical of feldspars Perkins and Henke,Plate 10; Klein and Hurlbut,p.
In thin section and under crossed-polarized light, Carlsbad twinning has a 'half and half' appearance, where one half of the grain is darker than the other half Perkins and Henke,Plate As the sample is rotated on a microscope stage, one twin will darken as the other lightens in crossed-polarized light.
A large grain with very noticeable Carlsbad twinning is located at the top of Figure 4. Well-established laboratory studies Klein and Hurlbut,p.
Mount Etna: Facts About Volcano's Eruptions
That is, as the magma cools, calcium-rich plagioclases crystallize first, which causes the remaining melt to become depleted in calcium and relatively enriched in sodium. Once temperatures further decline, more sodium-rich plagioclase begins to solidify from the melt and may surround the calcium-rich grains. This process produces zoning, where the older and more calcium-rich plagioclases are located in the core of the grains and the younger and more sodium-rich plagioclases occupy the rims.
Because of their crystalline and chemical differences, the calcium-rich plagioclase cores have somewhat different optical properties than the sodium-rich rims, which produce the noticeable concentric zoning in the grains in Austin's thin section photograph. Besides plagioclase feldspars, chemicals in cooling magmas deep within the Earth may organize into pyroxenes, amphiboles and a large variety of other minerals. In contrast, any melt that reaches the Earth's surface during an eruption will immediately quench into volcanic glass if it comes into contact with seawater or other surface waters.
The quenching process freezes the atoms in place and prevents them from organizing into crystals. In the presence of air, the lava may cool slowly enough that some VERY small minerals may grow. The highly disorganized volcanic glass matrix in Austin's Figure 4 appears black or 'isotropic' in crossed-polarized light.
Unlike most minerals, which lighten and darken in crossed-polarized light as the microscope stage is rotated, volcanic glass always remains consistently dark under crossed-polarized light.
Furthermore, unlike disorganized and quickly chilled volcanic glass, well-zoned and developed feldspar crystals, such as those shown in Figure 4, don't form overnight. On the basis of the glass and mineral textures and elementary melt chemistry, we know that the zoned plagioclases and other relatively large and well-developed minerals in Austin's dacite must have taken more time to grow than the surrounding glass matrix.
By using high-temperature ovens in undergraduate university laboratories or even crystal-growing kits and kitchen chemicals, a normally intelligent person can verify that coarse crystals take more time to grow than finer-grained materials. Clearly, basic crystal chemistry and physics dictates that zoned and other relatively large phenocrysts grew deep within the Earth and existed before the glass matrix that rapidly formed during the eruption.
Nevertheless, it is clear from Austin's essay that he has failed to incorporate the obviously diverse ages of the phenocrysts and the volcanic glass into his explanation for the origin of the dacite. Similarly, Swenson also fails to comprehend the indisputable history that is associated with the plagioclase zoning and to properly recognize the important age differences between the coarsest phenocrysts and the volcanic glass.
Even when phenocrysts as in Austin's Figure 4 and xenocrysts can be seen with an optical microscope, they can be extremely difficult, if not impossible, to effectively separate from the glass. I've attempted to separate very fined-grained minerals from glass in coal ashes by using magnetic separation and hydrofluoric and other acids. Specifically, Austin admits that most of his fractions are impure when he includes the term 'etc.
Furthermore, Austin's descriptions in the following statements clearly indicate that he FAILED to adequately separate the phenocrysts and possible xenocrysts from the volcanic glass. Because Austin clearly understands the heterogeneous composition of this 'fraction', he should have known that a K-Ar date on this mess would be meaningless.
Again, the mineral textures, as well as the laws of chemistry and physics, dictate that the calcium-rich plagioclase cores grew at higher temperatures before the sodium-rich rims and that glasses only formed once the melt erupted at the surface. Mafic microphenocrysts within these glassy particles were probably dominated by the strongly magnetic Fe-Ti oxide minerals. The microscopic examination of the 'heavy-magnetic concentrate' also revealed a trace quantity of iron fragments, obviously the magnetic contaminant unavoidably introduced from the milling of the dacite in the iron mortar.
No attempt was made to separate the hornblende from the Fe-Ti oxides, but further finer milling and use of heavy liquids should be considered. Although the contamination might have seriously affected any iron analyses, K and Ar analyses may not have been affected. The description of another one of Austin's 'fractions' indicates that it is also highly impure: These mafic microphenocrysts and fragments of mafic phenocrysts evidently increased the density of the attached glass particles above the critical density of 2.
This sample also had recognizable hornblende, evidently not completely isolated by magnetic separation. Because it was composed of finer particles meshit contained far fewer mafic particles with attached glass fragments than DOME-IH. This preparation is the purest mineral concentrate. Therefore, instead of dating the ages of the pyroxenes, he probably dated a mixture of mostly pyroxenes along with other minerals and volcanic glass.
Again, a K-Ar date on such an impure 'fraction' would be meaningless and a waste of time and money.
That is, Austin is not dating the volcanic glass or the pyroxenes in the dacite, but artificial mixtures, which result from incomplete separations. Because Austin admits that his separations were impure, how can he, Swenson and other YECs justify their claims that these dacite samples were a fair test of the validity of the K-Ar method? Why did Austin waste precious time and money analyzing samples that were known to contain mineral and glass impurities?
As a geologist, Austin should have known that minerals, especially zoned minerals, take more time to crystallize than quenched disorder glass. How could he expect the relatively large and sometimes zoned minerals to be as young as the glass?!! The following additional comments by Swenson demonstrate that he does not understand the mineralogy and chemistry of the dacite: However, Dalrymple  found that even volcanic glass can give wrong ages and rationalized that it can be contaminated by argon from older rock material.
In any debate, the debaters should provide the references or Internet links for their opponents so that the readers can evaluate both sides and really understand what's going on. Clearly, Swenson simply assumes that the volcanic glass contains 'excess argon.
In his essay, Austin even admits that the glass still needs to be separated and analyzed for argon. Furthermore, many studies for example, the Haulalai basalt; Funkhouser and Naughton, demonstrate that Swenson and other YECs cannot automatically assume that modern volcanic glass contains excess argon.
Although hypothesis 1 is plausible, until the argon isotope concentrations of the PURE glass are accurately measured for Austin's dacite if this is even possible we cannot properly evaluate this hypothesis.
- Etna dating site
Because Swenson does not provide a page number for his citation of Dalrymplethe identity of the volcanic glass with excess argon is uncertain. Perhaps, Swenson was referring to the following statement from Dalrymplep. Because the centers of the flows cool more slowly, any excess 40Ar and other gases can disperse out of the remaining melt before solidification.
While YECs explain geology by invoking talking snakes, magical fruit, and a mythical 'Flood', Dalrymple discusses legitimate chemistry and fluid physics, which is hardly relying on flimsy 'rationalizations' or implausible excuses.
Furthermore, contrary to Swenson's claims, nothing in Dalrymple excuses Austin's sloppy approach to K-Ar dating. In particular, YECs have no justification for automatically assuming that the dacite glass contains excess argon. Even if the dacite glass does contain excess argon, Dalrymplep.
Furthermore, if abundant excess argon is present in older rocks, Ar-Ar dating and K-Ar isochron dating can detect and eliminate its effects as examples, McDougall and Harrison,p.
Orthopyroxene retains the most argon, followed by hornblende, and finally, plagioclase.
While Austin claims that orthopyroxenes should retain the most argon followed by hornblende an amphibole and finally plagioclase, he provides no references to support this claim. In reality, the crystalline structures of amphiboles, unlike feldspars and pyroxenes, contain open channels, which can hold argon gas and other fluids Klein and Hurlbut,p.
I'm skeptical that the defects and fractures in the orthopyroxenes and feldspars of Austin's dacites could hold more excess argon per mineral volume than the relatively large open structures within the hornblendes Dickin,p. Therefore, IF hypothesis 1 was the only factor influencing the dates of Austin's samples, I would expect the hornblende-rich 'fraction' to provide an older date than the pyroxene- and feldspar-rich 'fractions.
From the above discussions, we already know that hypothesis 2 is a likely explanation for Austin's old dates. To evaluate hypothesis 3, we should look at the crystallization order of the phenocrysts as suggested by Bowen's Reaction Series.
The series states that certain minerals will crystallize in a melt at higher temperatures than other minerals. That is, different minerals have different freezing points. Mafic magnesium and iron-rich volcanic rocks, such as basalts, form from relatively hot melts C and hotter, Hall,p. Felsic silica-rich rocks, such as granites, form at cooler temperatures perhaps as cool as CHall,p.
The most common minerals in rocks of intermediate chemistry, such as dacites, are located towards the middle of the series. Bowen's Reaction Series is a very important concept that undergraduate students learn in their introductory physical geology courses.
To be exact, Bowen's Reaction Series was the one diagram that I was required to memorize when I took my first geology course in college. Although Bowen's Reaction Series was established long ago by field and laboratory studies, Swenson, Austin and other YECs repeatedly fail to comprehend its importance and how it can produce ancient phenocrysts, which may affect the radiometric dating of very young samples.
In a young volcanic rock, such as the Mt. Helen's dacite, the calcium-rich plagioclases may have formed thousands or even a few million years ago. Again, as a rock ages and 40Ar accumulates in both the glass and any 40K-bearing minerals, the differences in the ages of the materials becomes less significant. That is, if the glass quenched in an eruptionyears after the formation of the calcium-rich plagioclases, after Bowen's Reaction Series also predicts that pyroxenes will crystallize at higher temperatures before amphiboles.
Assuming that any argon contamination from Geochron's equipment hypothesis 2 is negligible, we see that the dates in Austin's table are consistent with the crystallization order in Bowen's Reaction Series. As expected, the purest pyroxene fraction provides an older date 2.