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Paleoenvironmental indications and cyclostratigraphic studies of sediments from tropical Lake Towuti obtained from downhole logging

Applicant Dr. Thomas Wonik
Subject Area Palaeontology
Geophysics
Term from 2017 to 2023
Project identifier Deutsche Forschungsgemeinschaft (DFG) - Project number 340239871
 
Final Report Year 2022

Final Report Abstract

Lake Towuti. We generated the first nearly complete age-depth model for the lacustrine facies of Lake Towuti and examined the potential of geophysical downhole logging for time estimation and lithological description. This study provides insights into the sedimentary history of the basin between radiometric ages derived from dating a tephra layer (797 ka) and 14C-ages (45 ka) in the cores. We derived an age-depth model that spans from late marine isotope stage MIS 23 to late MIS 6 (903 ± 11 ka to 131 ± 67 ka). Ohrid – Age-depth model from downhole data. In this study, we present an approach to construct age-depth models based on integrating downhole logging and seismic survey data when there are no samples available for dating. First, we interpret seismic data and correlate downhole logging data from three sites - DEEP, Pestani and Cerava - to the LR04 benthic stack. We crosscheck the resulting age-depth models using cyclostratigraphic methods. In the second step, we construct an artificial lithological log based on cluster analysis using the physical properties of the sediments and integrate it with the age-depth model. This allows an initial interpretation of the sedimentological history at Cerava and Pestani. Ohrid – Half-precession (HP). Next to a connection of HP cycles to interglacials, we see a more pronounced HP signal in the younger part of several proxy records. Although the HP signal is present in all of the investigated sites, we observe a more pronounced HP signal in the southeast compared to records from the north. The latter is consistent with the assumption that HP is an equatorial signal and can be transmitted northward via various pathways. The appearance of HP signals in mid- and high-latitude records can thus be an indicator for the intensity of the mechanisms driving these pathways. The African Monsoon probably plays a major role in this context, as its magnitude directly influences the climate systems of the Mediterranean and Southern Europe.

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