Onoma: CarilaoV (CarhV) TsikoV Panepisthmio …...Bibliography Sharp, Z. (2007) Principles of Stable...

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: h.tsikos@ru.ac.za

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