Medium: Taschenbuch, Einband: Kartoniert / Broschiert, Titel: Potassium Dating of Iron Meteorites, Autor: Shankar, Nirmala, Verlag: LAP Lambert Academic Publishing, Sprache: Englisch, Rubrik: Wirtschaft // Wirtschaftsratgeber, Seiten: 252, Informationen: Paperback, Gewicht: 393 gr, Verkäufer: averdo
Felsic is a term used in geology to refer to silicate minerals, magma, and rocks which are enriched in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium. The term combines the words "feldspar" and "silica." Felsic minerals are usually light in color and have specific gravities less than 3. Common felsic minerals include quartz, muscovite, orthoclase, and the sodium-rich plagioclase feldspars. The most common felsic rock is granite. On the opposite side of the rock spectrum are the iron and magnesium-rich mafic and ultramafic minerals and rocks. In modern usage, the term acid rock, although sometimes used as a synonym, refers to a high silica content (greater than 63% SiO2 by weight) volcanic rock such as rhyolite. The term was used more broadly in older geologic literature. It is considered archaic as the terms acidic and basic rock were based on an incorrect idea dating from the 1800s that silicic acid was the chief form of silicon occurring in rocks. The term felsic is related to but not derived from the German adjective felsig ("rocky").
This research involves the determination of the cosmic ray exposure ages of iron meteorites using 39K-40K-41K dating. Potassium was separated from nickel using ~ 4 mL of Chelex-100 resin and 15 mL of ammonium acetate (a mixture of equal volumes of 2 M acetic acid and 3 M aqueous ammonia) as eluent. Nickel was retained as a complex and potassium elutes out. The method is effective because of a low value for the blanks (~ 50 ng of potassium) that could be achieved. The concentration of the separated K, measured using Graphite furnace atomic absorption spectrometry (GFAAS), inductively coupled mass spectrometry (ICPMS) and isotope dilution mass spectrometry (IDMS) and will be used for the calculation of 39K-40K-41K exposure ages of iron meteorites. Potassium was successfully separated from multiple samples of 8 iron meteorites. The calculated CRE age (378 Ma) agrees for the meteorite Brownfield (355 Ma, Voshage and Feldmann, 1979) with the literature value. The literature value (645 Ma, Voshage and Feldmann, 1979) is ~3 times the value calculated (190 Ma, this work) for Picacho.
High Quality Content by WIKIPEDIA articles! Potassium-argon dating or K-Ar dating is a radiometric dating method used in geochronology and archeology. It is based on measurement of the product of the radioactive decay of an isotope of potassium (K), which is a common element found in many materials, such as micas, clay minerals, tephra, and evaporites, into argon. In these materials, the decay product 40Ar is not trapped by the rock while it is liquid (molten), but starts to accumulate when the rock solidifies (recrystallises). Time since recrystallization is calculated by measuring the ratio of the amount of 40Ar accumulated to the amount of 40K remaining. The long half-life of 40K allows the method to be used to calculate the absolute age of samples older than a few thousand years.
Luminescence Dating using single grains was a major technological advance as it provided for possibilities of dealing with heterogeneously bleached grain, with the prospect of isolating grain that were optically most bleached at the time of deposition. However at single grain level, complication due to heterogeneity in natural beta dose arises due to the fact that the entire potassium of a sediment matrix is contributed by few grains of K-feldspars with up to 14% potassium. And depending on the distance of a quartz grain from a feldspar grain the beta dose changes which leads to a range of beta doses. In this thesis, we computed this distribution of beta doses in natural samples using configuration averaging and Laplace Transform techniques. The spread in the dose distribution was explained solely with the number and positional fluctuations of feldspar grains in the sediment matrix. We then developed a new protocol for age computation using single grain that includes in it the effects of heterogeneous distribution of beta doses. Go through it and you will get new ideas to improve on it
Mount Aragat is a large andesitic-to-dacitic stratovolcano in NW Armenia about 40 km NW of the capital city of Yerevan. It is the highest point in Armenia, located in the province of Aragatsotn, northwest from Yerevan. Located on its slopes are the Byurakan Observatory and the medieval Amberd Fortress. The observatory is a historically significant facility responsible for a number of important photographic surveys. Mount Aragats is a popular destination for tourists, especially in summer. The 4095-m-high main edifice of Aragats is dissected by glaciers and is of Pliocene-to-Pleistocene age. However, parasitic cones and fissures are located on all sides of the volcano and were the source of large lava flows that descended its lower flanks. Several of these were considered to be of Holocene age, but later Potassium-Argon dating indicated mid- to late-Pleistocene ages. The youngest lower-flank flows have not been precisely dated, but are constrained as occurring between the end of the late-Pleistocene and 3000 BC
Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The name "organic" is historical, dating back to the 1st century.For many centuries, Western alchemists believed in vitalism, the theory that certain compounds could only be synthesized from their classical elements Earth, Water, Air and Fire by action of a "life-force" possessed only by organisms. The theory implied that these "organic" compounds were fundamentally different from the "inorganic" compounds that could be obtained from the elements by chemical manipulation. Vitalism survived for a while even after the rise of modern atomic theory and the replacement of the Aristotelian elements by those we know today. It first came under question in 1824, when Friedrich Wöhler synthesized oxalic acid, a compound known to occur only in living organisms, from cyanogen. A more decisive experiment was Wöhler''s 1828 synthesis of urea from the inorganic salts potassium cyanate and ammonium sulfate.