Preliminary Assessment of Organic Geochemistry in Sediments from the Transkei Basin (IODP Site U1581)


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Gabriele.Uenzelmann-Neben [ at ] awi.de

Abstract

A series of organic-rich sedimentary sequences that span the Paleocene through the Campanian was recovered from the Transkei Basin during IODP Expedition 392. Preliminary analyses of their organic geochemistry reveals suites of biomarkers that reflect diverse contributions of organic matter from both marine and terrestrial sources. The characteristics of the organic matter (OM) for a range of samples have been determined by shipboard and shore-based analyses that include evaluation of OM type and maturity by Rock-Eval pyrolysis, isotopic compositions of OM, and the distributions of aliphatic and aromatic biomarkers. Samples from both the Paleocene and Campanian contain series of C37 to C40 diunsaturated alkenones, including the earliest record of C38 alkadien-2-ones and C39 alkadien-3-ones [1]. Samples from a section of the Campanian (~72.5 Ma) reveal an abundance of C28 steradienes and steryl ethers potentially indicative of upwelling conditions [2]. Polyaromatic hydrocarbons within the sequence include compounds that reflect inputs of OM derived from angiosperms and paleofires [3,4]. Dominant hopanoids in the samples include -homohopane, hop-17(21)-ene, and 29-norhop-17(21)-ene, accompanied by fernenes [5], a C35 hopanoid thiophene [6] and also dammarenes [7] in Paleocene samples. These initial results provide evidence that biomarker profiling will facilitate determination of the sources of OM from the Late Cretaceous to the Paleocene in the Transkei Basin and paleoenvironmental conditions of deposition.



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Conference (Talk)
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Helmholtz Cross Cutting Activity (2021-2027)
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Event Details
Midwest Geobiology Symposium, 01 Oct 2022 - 01 Oct 2022, Evanston, Il, USA.
Eprint ID
56934
Cite as
Doiron, K. E. , Wagner, T. , Bijl, P. K. , Herrle, J. O. , Coenen, J. J. , Uenzelmann-Neben, G. , Bohaty, S. M. , Childress, L. B. and Brassell, S. , IODP Expedition 392 Science Party (2022): Preliminary Assessment of Organic Geochemistry in Sediments from the Transkei Basin (IODP Site U1581) , Midwest Geobiology Symposium, Evanston, Il, USA, 1 October 2022 - 1 October 2022 .


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