Secular variations

Suess, H. E. (1965). Secular variations of the cosmic-ray-produced carbon-14 in the atmosphere and their interpretation, /. Geophys. Res. 70,5937-5952. 

Secular variation of in calcite. Although it has been demonstrated in many studies that there is a wide range in measured for speleothems from a single cave site, past environmental conditions can be inferred from the variation of in... 

Figure 20. Secular variation in 5 U(0) for Bahamas flowstone sequence. Changes in 5 U(0) are related to uranium-series disequilibrium conditions in host limestone, periodic addition of new material with elevated (marine) 5 U(0), alpha recoil effects and variation in recharge, and hence water-rock interaction times (see text for details).

H.E. Suess, Secular variations of cosmogenic 14 C on earth their discovery and interpretation, Radiocarbon 28, 259 265 (1986). 

During the last 15 years intensive studies on the history of the atmospheric 14C/C ratio have been performed on tree-rings [20]. The results can be summarized as follows from 7000 BP (before present) to 2000 BP the average atmospheric 14C/C ratio had decreased by about 10 percent. Superimposed on this general trend are secular variations (Suess-Wiggles) of the order of 1 to 2 percent. In some time intervals a basic period of about 200 years is visible. 

The basic assumption of constant atmospheric X4C activity in radiocarbon dating is not strictly valid. We now have a record of the fluctuation of atmospheric 14C variations for the last 8,400 years B.P. obtained by measurement of the isotopes of carbon in dendrochron-ologically dated wood. Prior to contamination of atmospheric 14C activity by fossil fuel combustion and nuclear technology in the 20th century, the first-order secular variation can be closely approximated by a sine curve with a period of 10,600 years and an amplitude of ... 

Lerman, J. C., Radiocarbon Variations and Absolute Chronology, Discussion of causes of secular variations, Proc. XII Nobel Symp., New York, p. 609-610, 1970. 

Zhu XK, O Nions RK, Guo Y, Reynolds BC (2000) Secular variation of iron isotopes in north Atlantic Deep Water. Science 287 2000-2002. 

Hardie LA (1996) Secular variation in seawater chemistry An explanation for the coupled secular variation in the mineralogies of marine limestones and potash evaporites over the past 600 m.y. Geology 24 279-283... 

Zachara JM, Kukkadapu RK, Fredrickson JK, Gorby YA, Smith SC (2002) Biomineralization of poorly crystalline Fe(III) oxides by dissimilatory metal reducing bacteria (DMRB). Geomicrobio J 19 179-206 Zhu XK, O Nions RK, Guo YL, Reynolds BC (2000) Secular variation of iron isotopes in North Atlantic deep water. Science 287 2000-2002... 

Lithium is a conservative element in the ocean with a residence time of abont one million year. Its isotope composition is maintained by inputs of dissolved Li from rivers (average 5 Li + 23%c, Huh et al. 1998) and high-temperature hydrothermal fluids at ocean ridges at one hand and low temperature removal of Li into oceanic basalts and marine sediments at the other. Any variance in these sources and sinks thus should cause secular variations in the isotope composition of oceanic Li. And indeed in a first attempt Hoefs and Sywall (1997) interpreted Li isotope variations in well preserved carbonate shells as indicating secular variations of the oceanic Li-cycle. 

Knauth LP, Lowe DR (1978) Oxygen isotope geochemistry of cherts from the Onverwacht group (3,4 billion years), Transvaal, South Africa, with implications for secular variations in the isotopic composition of chert. Earth Planet Sci Lett 41 209-222 Knoll AH, Hayes JM, Kaufman AJ, Swett K, Lambert IB (1986) Secular variation in carbon isotope ratios from Upper Proterozoic successions of Svalbard and East Greenland. Nature 321 832-838... 

Wilson, R. M., Evidence for Solar-Cycle Forcing and Secular Variation in the Armagh Observatory Temperature Record (1844-1992), / Geophys. Res., 103, 11159-11171 (1998). 

Bates N.R. and Brand U. (1990) Secular variation of calcium carbonate mineralogy An evaluation of odid and micrite chemistries. Geologishe Rundschau (in press). 

Fischer A.G. and Arthur M.A. (1977) Secular variations in the pelagic realm. Special Publication Soc. Econ. Paleontologists and Mineralogists 25,19-50. 

Lumsden D.N. (1985) Secular variations in dolomite abundance in deep marine sediments. Geology 13, 766-769. 

Takahashi T Chipman D. and Volk T. (1983) Geographical, seasonal and secular variations of the partial pressure of CO2 in surface waters of the North Atlantic Ocean The results of the TTO Program. In Carbon Dioxide Science and Consensus (CONF-820970), II. 123-11.146, U.S. Dept, of Energy, Washington, D.C. (available from NTIS, Sprinfield, VA.). 

Veizer J. (1978) Secular variations in the composition of sedimentary carbonate rocks, II. Fe, Mn, Ca, Mg, Si, and minor constituents. Precambrian Research 6, 381-413. 

Wilkinson B.H. and Given R.K. (1986) Secular variation in abiotic marine carbonates constraints on Phanerozoic atmospheric carbon dioxide contents and oceanic Mg/Ca ratios. J. Geol. 94,321-334. 

Electrical conduction in the Mantle The magnitude and mechanism of electrical conductivity within the Earth have also been studied extensively. The radial distribution of electrical conductance in the Earth s interior may be estimated from studies of secular variations of the Earth s magnetic field. These measurements indicate a steep increase of electrical conductivity between depths of 400 and 1,000 km in the Mantle... 

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