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Owing to the isoclinal recumbent folding of metasedimentary units of the Cahill Formation, the typical rock sequence encountered at Koongarra is probably a tectono-stratigraphy (from youngest to oldest.) foliation of the schist sequence, which at Koongarra dips at 55° to the south-east.The dominant structural feature, however, is the reverse fault system that dips at about 60° to the south-east, sub-parallel to the dominant S foliation and lithological boundaries, just below the mineralized zone.
Of the various methods, uranium-thorium-lead (U-Th-Pb) was the first used and it is still widely employed today, particularly when zircons are present in the rocks to be dated.
But the method does not always give the “expected” results, leading to fundamental questions about its validity. some of the basic assumptions of the conventional Rb-Sr isochron method have to be modified and an observed isochron does not certainly define a valid age information for a geological system, even if a goodness of fit of the experimental data points is obtained in plotting Sr ratios, even an excellent line of best fit between ratios obtained from good cogenetic samples, and yet the resultant isochron and derived “age” have no distinct geological meaning.
The Koongarra uranium deposit occurs in a metamorphic terrain that has an Archean basement consisting of domes of granitoids and granitic gneisses (the Nanambu Complex), the nearest outcrop being 5 km to the north.
Some of the lowermost overlying Lower Proterozoic metasediments were accreted to these domes during amphibolite grade regional metamorphism (estimated to represent conditions of 5–8 kb and 550–630°C) at 1800–1870 Ma.
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I easily make I am Lynn from Thailand, I visited Hawaii once last month and fall in love with Hawaii and the people there would love to go back there again, I am looking for my Soulmate, hope it could be you! As with other isochron methods, the U-Pb isochron method has been questioned in the open literature, because often an excellent line of best fit between ratios obtained from a set of good cogenetic samples gives a resultant “isochron” and yields a derived “age” that has no distinct geological meaning.At Koongarra, Australia, U-Th-Pb isotopic studies of uranium ore, host rocks, and soils have produced an array of false “isochrons” that yield “ages” that are geologically meaningless.This paper was originally published in the Proceedings of the Third International Conference on Creationism, pp.497–504 (1994) and is reproduced here with the permission of the Creation Science Fellowship of Pittsburgh.Even a claimed near-concordant U-Pb ‘age’ of 862 Ma on one uraninite grain is identical to a false Pb-Pb isochron “age,” but neither can be connected to any geological event.Tags: Adult Dating, affair dating, sex dating