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Onoma: CarilaoV (CarhV) TsikoV
AnaplhrwthV KaqhghthV
Tmhma GewlogiaV
Panepisthmio Rhodes, Grahamstown, RSA
TopoV GennhshV: Aqhna
Hmeromhnia GennhshV: 21/03/1969
SpoudeV: EKPA (BSc); 1986-91
Rhodes (MSc, PhD): 1992-1998
Metadidaktorikh ereuna (1999-2005):
University of Johannesburg
University of Oxford
University of Aberdeen
Pedia ereunaV:
Koitasmatologia Fe/Mn
Gewchmeia staqerwn isotopwn
Biogewchmeia
Pallaioperiballonta
Epikoinwnia: [email protected]
PerissotereV plhroforieV:
http://www.ru.ac.za/primor/people/harilaostsikos
Stable isotopes & palaeoenvironments
Geology 301
Stable isotopes & palaeoenvironments
Stable isotopes & palaeoenvironments
Applications of stable
isotope geochemistry
in the geosciences
can be classified into
four main types
Thermometry
(T-dependent
fractionation between
two co-genetic phases)
Palaeoclimatology
(bones, ice and its gas
inclusions, carbonates,
cherts, clays, coal, etc.);
Reaction mechanisms
(open vs closed systems,
diffusion, bacterial-
thermogenic processes,
metabolic pathways)
Tracer studies
(rocks, fluids, plants,
food sources);
Stable isotopes & palaeoenvironments
The delta value
By convention, stable isotope data are reported as ratios relative to an
international standard, using the d (delta) notation:
d = [(Rx - Rstd) / Rstd] * 1000
where: • R is the ratio of the abundance of the heavy to the light isotope;
• x denotes the sample; and,
• std is the abbreviation for standard.
For the five light elements H, C, O, S and N, R is given by D/H, 13C/12C, 18O/16O, 34S/32S and 15N/14N respectively.
Delta values are reported in per mil (or parts per thousand); the symbol is ‰
The reference standards conventionally used in light stable isotope
geochemistry are: – SMOW, for Standard Mean Ocean Water, for H & O (of fluids and hydrous minerals);
– PDB, for Peedee Belemnite, for C & O (of carbonate minerals);
– CDT, for Canyon Diablo Troilite, for S; and,
– AIR (Atmospheric Nitrogen), for N
Stable isotopes & palaeoenvironments
O isotope fractionation between selected minerals & H2O as a function of T
Stable isotopes & palaeoenvironments
103lnaA-B = (a * 106/T2) + b (for high T’s); or
103lnaA-B = (a * 106/T) + b (for low T’s),
where: 103lnaA-B ≈ dA – dB
From: http://www.windows2universe.org/
Stable isotopes & palaeoenvironments
Stable isotopes & palaeoenvironments
CO2 + H2O = CH2O + O2 : large negative C isotope fractionation!
Stable isotopes & palaeoenvironments
Carbon cycle: reservoirs
and isotope signatures
Stable isotopes & palaeoenvironments
Stable isotopes & palaeoenvironments
The Cenomanian-Turonian
Oceanic Anoxic Event (OAE2)
Stable isotopes & palaeoenvironments
Global isotopic anatomy of the Cenomanian-Turonian Oceanic Anoxic Event (OAE2)
Stable isotopes & palaeoenvironments
Meteoric diagenesis
a. nitrate
5 (CH2O)106(NH3)16(H3PO4) + 472 HNO3 →
276 N2 + 520 CO2 + 5 H3PO4 + 886 H2O
b. manganese oxides
(CH2O)106(NH3)16(H3PO4) + 236 MnO2 + 472 H+ →
236 Mn2+ + 106 CO2 + 8 N2 + H3PO4 + 336 H2O
c. iron oxides
(CH2O)106(NH3)16(H3PO4) + 212 Fe2O3 + 848 H+ →
424 Fe2+ + 106 CO2 + 16 NH3 + H3PO4 + 530 H2O
d. sulphate
(CH2O)106(NH3)16(H3PO4) + 55 SO42- →
106 CO2 + 16 NH3 + 55 S2- + H3PO4 + 106 H2O
e. Methanogenesis (d13C of methane as low as -110 per mil!)
Stable isotopes & palaeoenvironments
Organic matter diagenesis
Stable isotope records across the Paleocene-Eocene boundary.
Stable isotopes & palaeoenvironments
Stable isotopes in the
Campanian Mishash
Formation, Israel
Stable isotopes & palaeoenvironments
Stable isotopes & palaeoenvironments
Stable isotopes in the hydrological cycle
Vertical d18O section of the Samail ophiolite, Oman
Stable isotopes & palaeoenvironments
Variations in d13C of atmospheric CO2 as a function of age
Stable isotopes & palaeoenvironments
Bibliography
Sharp, Z. (2007) Principles of Stable isotope Geochemistry.
Prentice Hall, NJ, 344p.
Additional references
Chester, R. (1993) Marine Geochemistry. Chapman & Hall, London,
698p.
Faure, G. (1998) Principles and Applications of Geochemistry (2nd
Edition). Prentice Hall, NJ, 600p.
Hoefs, J. (2004) Stable Isotope Geochemistry. Springer, Berlin,
244p.
James, R & the Open University Oceanography Course Team
(2005) Marine Biogeochemical Cycles. Open University
Oceanography Series, S330 Volume 5, Elsevier Butterworth-
Heinemann, 130p.
Stable isotopes & palaeoenvironments