x
Peter Stille and Graham Shields
4.3 Anthropogenic Contamination in River Water Observed Using Isotope
Methods (R, Rhine) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7 1
4.3. I Oxygen Isotopes ................................................................................ 71
4.3.2 Strontium Isotopes ............................................................................ 72
4.3.3 Carbon Isotopes ................................................................................ 76
4.4 Contamination of Flowing Water and Groundwater after the Reactor
Accident at Chernobyl Shown Using Released Radionuclides ....................... 76
4.5 Radionuclides as Tracers in Sedimentology .................................................... 83
46 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
87
5 Isotopic Composition of Seawater Past and Present (Sr, Nd, Pb. Os,
Ce) ....................................................................................................................
89
5. I Sr Isotopic Composition of Seawater: Tectonic Proxy and Stratigraphic
Toot ..................................................................................................................
90
5. I. I Microstratigraphy ..............................................................................
91
5.1.2 The Role of Diagenesis in 5r I~otope Stratigraphy ..........................
97
51.3 Micrt~stra~igraphy at the Precambdan/Cambrian Boundary? ........ 102
5.1.4 Mass Balance Calculations ............................................................
106
5.1.5 The Influence of Groundwater on the Sr Isotopic Composition
of Seawater .....................................................................................
108
5.2 Nd Isotopic Composition of Seawater: Tracer of Water Circulation
Patterns ..........................................................................................................
1 1 2
5.2.1 Calculation of the Residence Time of Nd in Seawater and of
the Time Necessary for the "I~orough Mixing of Two Oceans
or Water Bodies ..............................................................................
114
5.2.2 Possibilities Ior the Derivation o[ 1he Nd Isotopic
Composition of Paleo-Oceans ........................................................
119
5.2.3 Nd Isotopic Evolution in Seawater ................................................. 126
5.2.4 The Closing of the Tethys and the Opening of the Atlantic ........... 128
5.3 Tracing Ocean Currents Using Nd and Pb Isotopes ......................................
133
5.3.1 Ocean Currents and Nd Isotopes ....................................................
133
5 3,2 Ocean Currents and Pb Isotopes ..................................................... i 35
5.4 Ce Isotopic Composmon of Seawater: Another Potential Tracer of
Ocean Circulation? ........................................................................................
140
5.5 O'.. Isotopic Composition of Seawater: Stratigraphic Tool or Tracer of
Ocean Circulation Patterns'? ...........................................................................
142
5.5. I Changes in Seawater Os Isotopic Ratio through Geologic
Time ................................................................................................
144
5.5.2 Meteorite Impact at the Cretaceous-Tertiary (K-T) Boundary.? .... 146
5.6 References ......................................................................................................
150