Paleosols from Pakistan, Greece, and South Dakota: Strengths and pitfalls of the use of carbon isotopes in paleoecologic reconstruction
- Univ. of Arizona, Tucson, AZ (United States). Dept. of Geosciences
- Univ. of Utah, Salt Lake City, UT (United States). Dept. of Geology and Geophysics
The delta C-13 of soil carbonates in paleosols can be used to reconstruct the proportion of C[sub 3] and C[sub 4] plants that grew on the site during pedogenesis. This reconstruction is only possible where: (1) soil carbonate, not other secondary carbonates, is sampled, (2) carbon isotopes have not undergone post-burial replacement or exchange, and (3) there is no detrital contamination of soil nodules. Preservation of soil organic matter provides the simplest test of all these conditions. In modern soils coexisting soil carbonate and organic matter differ by 14--17%. This difference is preserved in Mio-Pliocene paleosols from the Siwalik Sequence in Pakistan, verifying a pedogenic origin, but not in coexisting carbonate and organic layers from Pikermi in Greece. Minor detrital contamination is present in some Siwalik soil carbonates, but this can be quantified by analyzing entire paleosol profiles. Other post-pedogenic carbonate cements are also present by they display very different delta C-13 and delta O-18 values from those in soil carbonates, aging suggesting that post-pedogenic exchange has not occurred. In the Badlands of South Dakota, preliminary results show that all sampled carbonate phases, including those in paleosols, display very homogeneous delta C-13 values of around [minus]7 to [minus]8%, indicating that (1) no pedogenic carbonate is present, (2) post-burial isotopic alteration may have occurred, or (3) Oligocene atmospheric pCO[sub 2] was substantially higher than today's.
- OSTI ID:
- 5808181
- Report Number(s):
- CONF-921058--
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Journal Name: Geological Society of America, Abstracts with Programs; (United States) Vol. 24:7; ISSN GAAPBC; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
Similar Records
An oxygen isotope study of illite and calcite in three Appalachian Paleozoic vertic paleosols
Carbonate-paleosol genesis in the Plio-Pleistocene St. David Formation, southeastern Arizona
Related Subjects
580000* -- Geosciences
ASIA
CARBON 13
CARBON ISOTOPES
CARBONATE ROCKS
CENOZOIC ERA
CHEMISTRY
DEVELOPED COUNTRIES
DEVELOPING COUNTRIES
EUROPE
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
GEOCHEMISTRY
GEOLOGIC AGES
GEOLOGIC STRUCTURES
GREECE
ISOTOPE RATIO
ISOTOPES
LIGHT NUCLEI
NORTH AMERICA
NUCLEI
OXYGEN 18
OXYGEN ISOTOPES
PAKISTAN
PALEOCLIMATOLOGY
PALEONTOLOGY
ROCKS
SEDIMENTARY BASINS
SEDIMENTARY ROCKS
SOIL CHEMISTRY
SOUTH DAKOTA
STABLE ISOTOPES
TERTIARY PERIOD
USA