Uranium-series dating

Once uranium is incorporated into buried bone, shell, coral, or speleothems, the isotope uranium-235 decays, initially into the short-lived isotope (thorium-231) and then into long-lived protoactinium-231. Uranium-238, on the other hand, decays first into two successive short-lived isotopes (thorium-234 and protoactinium-234) and only then into a long-lived isotope, uranium-234 (see Fig. 12). The decay of uranium-235 to long-lived protoactinium-231 is used to date events up to 150,000 years in age that of uranium-234 (derived from uranium-238) to thorium-230 is of use for dating events within the time range 1000-500,000 years. [Pg.59]

Marble. The word marble is used as the common name for two types of monomineral rocks one derived from limestone and therefore composed of calcium carbonate, the other derived from dolomite and composed of calcium magnesium carbonate. Extremely high pressures and heat during past geological times modified the structure of both limestone and dolomite, compacting them into a characteristic crystal structure. Most marble is white however, minor and trace amounts of metallic impurities cause the formation of stains in a variety of colors, hues, and patterns, or of colored marble. [Pg.59]

Marble occurs in many locations on the crust of the earth, so that many types of marble were known to the ancients. White Pentelic marble, from [Pg.59]

Quartzite. Quartzite is a very compact, exceptionally hard and tough meta-morphic rock derived from sandstone. It consists mainly of rather large crystals of quartz (composed of silicon dioxide) naturally cemented by secondary quartz. Most varieties of quartzite contain over 90% quartz, and in some cases the quartz content exceeds 95% of the total weight of the stone. The color of most quartzite is white or light yellow, but if it contains iron oxide impurities it is red, while other metal oxide impurities may cause the rock to display patchy color variations. Quartzite is very hard, which makes it difficult to quarry. Nevertheless, because of its strength and resistance to weathering, it has occasionally been used for construchon, sculphng statuary, and ornamentation. [Pg.61]

Pigments are intensely colored and finely powdered solids used (mainly in paints) to impart color to other materials. Since early antiquity most pig- [Pg.62]

Edwards RL, Gallup CD, Cheng H (2003) Uranium-series dating of marine and lacustrine carbonates. Rev Mineral Geochem 52 363-405... [Pg.1]

Figure 1. Schematic diagram showing a TRU-spec extraction chromatography method for separation of uranium, thorium, protactinium, and radium from a single rock aliquot. Further purification for each element is normally necessary for mass spectrometric analysis. Analysis of a single aliquot reduces sample size requirements and facilitates evaluation of uranium-series dating concordance for volcanic rocks and carbonates. For TIMS work where ionization is negatively influenced by the presence of residual extractant, inert beads are used to help remove dissolved extractant from the eluant.

Figure 1. Histogram of measurements of molar U/Ca ratio in a number of samples of reef-building corals and one giant clam sample (after Edwards 1988). Also indicated is the U/Ca ratio of seawater. This illustrates the point that corals do not fractionate U from Ca by large amounts when they make their skeletons. U/Ca ratios of corals are similar to values from inorganically precipitated marine aragonite. Mollusks along with most other biogenic minerals exclude uranium. Note that the horizontal axis is on a log scale and that the U/Ca ratio of the clam is almost 5 orders of magnitude lower than that of the corals. This difference is the fundamental reason why there are difficulties with uranium-series dating of mollusks.

$Figure 1. Histogram of measurements of molar U/Ca ratio in a number of samples of reef-building corals and one giant clam sample (after Edwards 1988). Also indicated is the U/Ca ratio of seawater. This illustrates the point that corals do not fractionate U from Ca by large amounts when they make their skeletons. U/Ca ratios of corals are similar to values from inorganically precipitated marine aragonite. Mollusks along with most other biogenic minerals exclude uranium. Note that the horizontal axis is on a log scale and that the U/Ca ratio of the clam is almost 5 orders of magnitude lower than that of the corals. This difference is the fundamental reason why there are difficulties with uranium-series dating of mollusks.$

Li WX, Lundberg J, Dickin AP, Ford DC, Schwarcz HP, McNutt R, Williams D (1989) High precision mass-spectrometric uranium-series dating of cave deposits and implications for paleoclimate studies. Nature 339 534-536... [Pg.403]

Rosholt NJ (1967) Open system model for uranium-series dating of Pleistocene samples. In Radioactive Dating and Methods of low-level Counting. 1. A. E. A. Proc Ser Publ, SM-87/50, p 299-311 Rosholt JN, Antal PS (1962) Evaluation of the Pa /U-Th °/U method for dating Pleistocene carbonate rocks. US Geol Survey Prof Paper 450-E 108-lll... [Pg.404]

Uranium-series dating is by far the most widely-used dating technique applied to speleothems, and is only applicable to material that is currently in a state of disequilibrium. Given the rates of ingrowth of daughter isotopes of Pa and °Th, conditions of uranium-series disequilibrium in systems which have remained isotopically-closed are generally restricted to materials < 500 ka... [Pg.410]

Uranium-series dating of speleothems is based on the extreme fractionation of the... [Pg.410]

Ayliffe LK, Veeh HH (1988) Uranium-series dating of speleothems and bones from Victoria Cave, Naracoorte, South Australia. Chem Geol 72 11-234... [Pg.451]

Harmon RS, Schwarcz HP, O Neil JR (1979) D/H ratios in speleothem fluid inclusions A grride to variatiorrs in the isotopic compositions of meteoric precipitation Earth Planet Sci Lett 42 254-266 Harmon RS, Thompson P, Schwarcz HP, Ford DC (1975a) Late Pleistocene paleoclimates of North America as irrferred from stable isotope studies of speleothems. Quat Res 9 54-70 Harmon RS, Thompson P, Schwarcz HP, Ford DC (1975b) Uranium-series dating of speleothems. Nat Speleolo cal Soc Bull 37 21-33... [Pg.455]

Kaufman A, Broecker WS (1965) Comparison of °Th and " C ages for carbonate materials from Lakes Lahontan and Bonneville. J Geophys Res 70 4039-4054 Kaufman A, Ku T-L, Luo S (1995) Uranium-series dating of camotites Concordance between Th-230 and Pa-231 ages. Chem Geol 120 175-181... [Pg.456]

Lauritzen S-E, Onac BP (1995) Uranium-series dating of speleothems from Romartian caves. Theor Appl Karst 8 25-36... [Pg.457]

Yuan SX, Chen TM, Gao SJ, Hu YQ (1991) Study on uranium series dating of fossil bones from Zhoukoudian sites Acta Anthropol. Sinica 10 189-193 (in Chinese)... [Pg.460]

Edmonds HN, Moran SB, Hoff JA, Smith JN, Edwards RL (1998) Protactinium-231 and Thorium-230 abundances and high scavenging rates in the Western Arctic ocean. Science 280 405-407 Edwards RL, Gallup CD, Cheng H (2003) Uranium-series dating of marine and lacustrine carbonates. Rev Mineral Geochem 52 363-405... [Pg.525]

Ludwig KR, Paces JB (2002) Uranium-series dating of pedogenic sihca and carbonate, Crater Flat, Nevada. Geochim Cosmochim Acta 66 487-506... [Pg.572]

Schmeide K, Pompe S, Buhner M, Heise KH, Bernhard G, Nitsche H (2000) Uranium (VI) sorption onto phyllite and selected minerals in the presence of humic acid. Radiochim Acta 88 723-728 Schwarcz HP, Latham AG (1989) Dirty calcites 1. Uranium series dating of contaminated calcite using leachate alone. Chem Geol 80 35-43... [Pg.575]

Griin R, Thome A (1997) Dating the Ngandong humans. Science 276 1575 Hille P (1979) An open system model for uranium series dating. Earth Planet Sci Lett 42 138-142 Ikeya M (1982) A model of linear uranium accumulation for ESR age of Heidelberg (Mauer) and Tautavel bones. Jap J App Phys (Lett) 21 690-692... [Pg.627]

Millard AR, Pike AWG (1999) Uranium-series dating of the Tabun Neanderthal a cautionary note. J Human Evol 36 581-585... [Pg.627]

Rae AM, Hedges REM, Ivanovich M (1989) Further studies for uranium-series dating of fossil bones. Appl Geochem 4 331-337... [Pg.628]

Rae AM, Ivanovich M (1986) Successful application of uranium series dating of fossil bone. Appl Geochem 1 419-426... [Pg.628]

Roberts RG, Jones R, Smith MA (1990) Thermoluminescence dating of a 50,000 year old human occupation site in northern Australia. Nature 345 153-156 Schwarcz HP (1992) Uranium-series dating and the origin of modem man. In The Origin of Modem Humans and the Impact of Chronometric Dating. Aitken MJ, Stringer CB, Mellars PA (eds) Princeton University Press, Princeton, p. 12-16... [Pg.628]

Szabo BJ, Rosholt JN (1969) Uranium-series dating of Pleistocene molluscan shells from southern California - an open system model. J Geophys Res 74 3253-3260 Thome A, Griin R, Spooner NA, Simpson JJ, McCulloch M, Cumoe D (1999) Australia s oldest human remains age of the Lake Mungo 3 skeleton. J Human Evol 36 591-612 Wolpoff M (1989) Multiregional evolution the fossil alternative to Eden. In The Human Revolution. [Pg.628]

Zhou LP, McDermott F, Rhodes EJ, Marseglia EA, Mellars PA (1997) ESR and mass-spectrometric uranium-series dating studies of a mammoth tooth from Stanton Harcourt, Oxfordshire, England. Quat Sci Rev (Quat Geochron) 16 445-454... [Pg.629]

Uranium-237 Alpha recoil tracks and uranium series dating... [Pg.66]

Uranium Series Dating. Reliable dating of bone is possible when using the technique known as uranium series dating (see Textbox 16). The technique, which is also based on measuring relative amounts of uranium, makes possible dating very old bones, beyond the range that can be dated with radiocarbon, that is, over 40,000 years and up to 500,000 years old (Schwarcz 1997 Ivanovich and Harmon 1992). [Pg.413]

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