Additional co-authors: TJ Heaton, AG Hogg, KA Hughen, KF Kaiser, B Kromer, SW Manning, RW Reimer, DA Richards, JR Southon, S Talamo, CSM Turney, J van der Plicht, CE Weyhenmeyer

/pdf/intcal13-and-marine13-radiocarbon-age-calibration-curves-0-4f3vsbzfqx.pdf

IntCal13 and Marine13 radiocarbon age calibration curves 0-50,000 years cal BP

This chapter reviews the present-day composition of the continental crust, the methods employed to derive these estimates, and the implications of the continental crust composition for the formation of the continents, Earth differentiation, and its geochemical inventories. We review the composition of the upper, middle, and lower continental crust. We then examine the bulk crust composition and the implications of this composition for crust generation and modification processes. Finally, we compare the Earth's crust with those of the other terrestrial planets in our solar system and speculate about what unique processes on Earth have given rise to this unusual crustal distribution.

/pdf/composition-of-the-continental-crust-2hxz49vsod.pdf

Composition of the Continental Crust

Plesovice zircon : A new natural reference material for U-Pb and Hf isotopic microanalysis

3.01 – Composition of the Continental Crust

Hf isotopic compositions of the standard zircons and baddeleyites used in U-Pb geochronology

Application of Fe isotopes to tracing the geochemical and biological cycling of Fe

Kinetic and equilibrium Fe isotope fractionation between aqueous Fe(II) and Fe(III)

The largest Fe isotope fractionations occur during redox changes, as well as differences in bonding, but these are expressed only in natural environments in which significant quantities of Fe may be mobilized and separated. At the circumneutral pH of most low-temperature

/pdf/the-iron-isotope-fingerprints-of-redox-and-biogeochemical-11t1uek0hc.pdf

The Iron Isotope Fingerprints of Redox and Biogeochemical Cycling in Modern and Ancient Earth

The (56)Fe/(54)Fe of Fe-bearing phases precipitated in sedimentary environments varies by 2.5 per mil (delta(56)Fe values of +0.9 to -1. 6 per mil). In contrast, the (56)Fe/(54)Fe of Fe-bearing phases in igneous rocks from Earth and the moon does not vary measurably (delta(56)Fe = 0.0 +/- 0.3 per mil). Experiments with dissimilatory Fe-reducing bacteria of the genus Shewanella algae grown on a ferrihydrite substrate indicate that the delta(56)Fe of ferrous Fe in solution is isotopically lighter than the ferrihydrite substrate by 1.3 per mil. Therefore, the range in delta(56)Fe values of sedimentary rocks may reflect biogenic fractionation, and the isotopic composition of Fe may be used to trace the distribution of microorganisms in modern and ancient Earth.

https://science.sciencemag.org/content/sci/285/5435/1889.full.pdf

Clark M. Johnson

Papers

Application of Fe isotopes to tracing the geochemical and biological cycling of Fe

Kinetic and equilibrium Fe isotope fractionation between aqueous Fe(II) and Fe(III)

The Iron Isotope Fingerprints of Redox and Biogeochemical Cycling in Modern and Ancient Earth

Iron isotope biosignatures.

Geochemistry of non-traditional stable isotopes