Geoscience Reference
In-Depth Information
7
Stable isotope analysis and trace element geochemistry
Se non e vero, e molto ben trovato
.
It may not be true, but it is very well contrived.
Giordano Bruno (1548-1600)
De gl'heroici furori
(1585)
7.1 Introduction
We saw in
Chapter 6
that the different isotopes of a chemical element have the same
number of protons but different numbers of neutrons and noted that individual isotopes
of an element are termed nuclides. The focus of this chapter is on nuclides that are
stable through time, as opposed to those that are unstable and undergo radioactive
decay, making them especially valuable for dating rocks and sediments (
Chapter 6
).
This chapter is not a treatise on stable isotopes - excellent monographs and reviews
are available for those seeking more information (Dansgaard,
1964
; Yurtsever,
1975
;
Pearson and Coplen,
1978
; Yurtsever and Gat,
1981
;Faure,
1986
; Sealy,
1986
;Hoefs,
1997
; McDermott,
2004
; Fairchild et al.,
2006
; Leng and Barker,
2006
;Lengand
Barker,
2007
; Leng and Sloane,
2008
). Rather, it seeks to provide examples of how
stable isotopes have been used to reconstruct climatic change in deserts. A great deal
of progress has been made in this field during the past forty years. When Flint (
1971
)
and Butzer (
1971
) published their monumental monographs on geologically recent
global environmental changes, they hardly mentioned the use of stable isotopes in
reconstructing past terrestrial environments. Today, stable isotopes are one of the most
widely used indicators of climate change in the ever-growing and impressive arsenal
of available tools listed in
Tabl e 1 . 2
of
Chapter 1
.
The use of stable isotope analysis has proven to be a very powerful tool in recon-
structing past environmental fluctuations in deserts, desert margins and the oceans
surrounding the deserts. Because carbon, oxygen and hydrogen are abundant in rocks,
sediments, plants, rivers and lakes, the stable isotopes of these three elements are the
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