A Comparative Study of Molecular Paleosalinity Indicators: Chromans, Tocopherols and C20 Isoprenoid Thiophenes in Miocene Lake Sediments (Nördlinger Ries, Southern Germany)

Authors: Barakat A.O.¹; Rullkötter J.²

Source: Aquatic Geochemistry, Volume 3, Number 2, 1997 , pp. 169-190(22)

Publisher: Springer

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Abstract:

Distributions of alkylated chromans and C20 isoprenoid thiophenes were investigated in four organic-matter- and sulfur-rich black shales of Miocene age deposited in the ancient crater lake of the Nördlinger Ries (southern Germany), a meteorite impact crater. Paleosalinity parameters based on these compound classes generally confirm sedimentological evidence of increased salinity over certain periods of the lake's history, but the data from both groups of compounds are not consistent. Diagenetically related molecular constituents were therefore studied to estimate the sensitivity of these parameters. The influence of thiolanes on the isoprenoid thiophene parameter was found to be low, whereas too little is known at present about the origin and diagenetic fate of alkylated chromans to conclude definitely that an alkylated chroman paleosalinity parameter can reliably be applied to a wide range of depositional settings.

Keywords: Chromans; homohopenes; isoprenoid thiolanes; isoprenoid thiophenes; methylated MTTC; Nördlinger Ries; tocopherols

Language: English

Document Type: Regular paper

Affiliations: 1: Department of Environmental Sciences, Faculty of Science, Alexandria University, 21511 Alexandria, Egypt 2: Author for Correspondence Institut für Chemie und Biologie des Meeres (ICBM), Carl von Ossietzky Universität Oldenburg, Postfach 2503, D-26111 Oldenburg, Germany

Publication date: 1997-01-01