Geochemistry of Upper Miocene Kudankulam Limestones, Southern India
- 1 January 2003
- journal article
- Published by Informa UK Limited in International Geology Review
- Vol. 45 (1), 16-26
- https://doi.org/10.2747/0020-6814.45.1.16
Abstract
Concentrations of major, trace, and rare-earth elements (REE) were measured in shallow marine limestone samples of the upper Miocene Kudankulam Formation, southern India, in order to investigate the geochemical variations among various litho-units. The CaCO3 content is higher in algal limestone (AL; 92 ± 1, n = 3) and clastic limestone (CL; 90 ± 2, n = 3) than sandy shell limestone (SSL; 81 ± 1, n = 3). All trace elements exhibit lower concentrations than post-Archean Australian Shale (PAAS) values, except one SSL sample. Large variations in ΣREE content are observed among CL, SSL, and AL (~14-142, ~68-124, and ~38-98, respectively). Almost all limestone samples analyzed from the Kudankulam Formation show a small negative cerium anomaly (Ce/Ce* ~0.8-0.9), except one AL sample, which lacks this cerium anomaly (Ce/Ce* ~1.04). Variations in Ce anomalies and ΣREE contents in Kudankulam limestone samples are mainly controlled by the amount of terrigenous sediments and diagenetic behavior. Shale-normalized REE patterns and (La/Yb)s, La/Sc, La/Th, and Th/Sc ratios suggest that the detrital sediments present in the limestones were probably derived from felsic source rocks. The observed low content of U (0.9 ± 0.5, n = 9) and U/Th (0.2 ± 0.1, n = 9) ratio in these limestones are probably related to an oxygen-rich environment.Keywords
This publication has 41 references indexed in Scilit:
- Geochemistry of fine-grained clastic sediments in the Archean Abitibi greenstone belt, Canada: Implications for provenance and tectonic settingGeochimica et Cosmochimica Acta, 1990
- The rare earth elements in rivers, estuaries, and coastal seas and their significance to the composition of ocean watersGeochimica et Cosmochimica Acta, 1990
- Uranium removal in oceanic sediments and the oceanic U balanceEarth and Planetary Science Letters, 1990
- Concentration, oxidation state, and particulate flux of uranium in the Black SeaGeochimica et Cosmochimica Acta, 1989
- The oceanic chemistry of the rare-earth elementsPhilosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences, 1988
- Rare earth element distributions in anoxic waters of the Cariaco TrenchGeochimica et Cosmochimica Acta, 1988
- Rare earth elements in the pore waters of reducing nearshore sedimentsEarth and Planetary Science Letters, 1987
- Trace element characteristics of graywackes and tectonic setting discrimination of sedimentary basinsBeiträge zur Mineralogie und Petrographie, 1986
- Geology, with special reference to the PrecambrianPublished by Springer Science and Business Media LLC ,1984
- Removal of 230Th and 231Pa at ocean marginsEarth and Planetary Science Letters, 1983