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December 2024 | Petrolabers at the AGU in Washington, USA
Four presentations by petrolab members were presented this coming early December at the AGU meeting in Washington! Olabayo presented the latest results from his research in a poster. His presentation was very crowded and he didn't stop presenting his project!
In parallel, Parth presented the results from the two lakes he is studying in Yemen, with a highway of scientists worldwide visiting his poster. Abdelaziz, our former MSc student presented the results from his thesis (soon to be published in a scientific paper!) and Danish presented the latest data from Erk-el-Ahmar project.
We are all very proud of the collection of projects presented across the Atlantic! Congrats!
November 2024 | A scientific visit and talk at OAJ Institute of Science - Bhavnagar, India
As part of a visit to India, Nicolas visited OAJ Institute of Science in Bhavnagar in India and gave a talk on latest studies carried out at the lab by his team. OAJ is one of the best institute in the Gujarat State, committed to provide a positive, motivated & competitive environment to students who aim to continue at high end academic institutions and help to give the students the possibility to shine at national and international levels.
We are very proud to be committed to excellence and to cooperate with high-end institutions worldwide, such as OAJ! The visit was filmed and well covered in social media.
October 2024 | Mfoniso's visit to the University of Lund, Sweden
Mfoniso got a highly competitive grant for visiting the University of Lund (Sweden) to carry out his research at the paleomagnetic lab in scientific cooperation with Prof Andreas Nilsson. He is working on integrating paleomagnetic data from two lakes in Patagonia, which will allow him to better constrain the age of these two lake sediment records. Congrats!
July 2024 | TED talk by Prof Nicolas Waldmann
Prof Nicolas Waldmann gave a TED talk as part of the ambassadors program of the university. The talk was 5 minutes long and was on climate warming. The ambassadors program aim to enlarge the scientific, educational and financial possibilities at the university by increasing fundraising. It was a very intensive course program, with several steps and actions that culminated with the TED event in front of the whole university. Link here.
ניקולס.mp4June 2024 | Shah Parth defended his PhD thesis!
Congrats to Dr Shah Parth who just defended his PhD thesis! Parth's thesis deals with past climate and environmental reconstruction as retrieved from a multidisciplinary study of sediments cores from two lakes in southern Arabian Peninsula. The results of his study were published in several papers and he is currently working on more publications. Stay tuned for more updates coming out of his research!
May 2024 | Mfoniso presented his results at the Geological Society of Israel annual meeting
Mfoniso Anieti went to Jerusalem to present the results from his MSc research at the GSI meeting. His project deals with paleomagnetic data from Lake Fagnano in Tierra del Fuego (southernmost South America). His poster was very well attended by colleagues from several universities in Israel.
Well done, Mfoniso!
April 2024 | Shah Parth gave a talk at CSD, University of Minnesota!
Shah Parth gave an excellent talk on the results of his PhD thesis at the University of Minnesota's CSD facility. Parth got a scholarship for visiting CSD facility for sampling more lake sediments as part of his research. CSD personnel invited him to give a talk. So, congrats Parth!
March 2024 | New paper with Petrolabers in Biogeosciences!
A new paper just came out in Biogeoscience. In this work, the reliability of long-term climate signals registered in the sediments of Lake Chala by comparing downcore variations in GDGT distributions with major phases in lake-system evolution were assessed. The record suggest that during early lake history (ca. 180–200 ka) the distinct mixing-related depth zones with which specific GDGT producers are associated in the modern-day lake were not yet formed, likely due the absence of chemical water-column stratification. Consequently absolute GDGT concentrations dating to this period are relatively low, proxies sensitive to water-column stratification (e.g., branched versus isoprenoid tetraether (BIT) index) display highly irregular temporal variability, and correlations between proxies are dissimilar to expectations based on modern-system understanding. A sequence of lake-system changes between ca. 180–200 and ca. 80 ka first established and then strengthened the chemical density gradient, promoting meromictic conditions despite the overall decrease in lake depth due to the basin gradually being filled up with sediments. From ca. 180 ka onward some GDGTs and derived proxies display strong ∼ 23 kyr periodicity (precession-driven insolation). Our results suggest that GDGT-based temperature and moisture-balance proxies in Lake Chala sediments reflect the climate history of eastern equatorial Africa from at least ca. 160 ka onwards. This work confirms the potential of lacustrine GDGTs for elucidating the climate history of tropical regions at Quaternary timescales, provided they are applied to suitably high-quality sediment archives. Additionally, their interpretation should incorporate a broader understanding of the extent to which lake-system evolution limits the extrapolation back in time of proxy-climate relationships established in the modern system.
Schematic representation of the spatial distribution of GDGTs and their producers in the water column of modern-day Lake Chala during the two seasonal extremes of (a) highly stratified (shallow oxycline) conditions associated with the rainy season and (b) enhanced upper-water-column mixing associated with windy and dry conditions, as shown by analysis of SPM and settling particles.
February 2024 | New paper just came out of the oven from PetroLab!
A new paper just came out in Journal of Paleolimnology. In this work, we disentangled alteration processes occurring at the redox front below the sediment–water interface of a ventilated deep-water lake (Lago Fagnano, Argentina/Chile). A sequential extraction protocol was applied to characterize two reactive Fe pools: Fe oxyhydroxides and reduced iron. Subsequently, Fe isotopes were constrained to determine the main processes mobilizing Fe. At the redox front, ferric minerals reach a δ56Fe value of − 1.3‰ resulting from oxidation of dissolved Fe likely following a Rayleigh distillation effect. Dissolved Fe is produced right below via Fe reduction, as shown by the low ferric Fe content. Our observations delineate a redox cycle and a redox horizon undergoing constant upward migration, initiated by regular sedimentation. However, during events of increased rapid sedimentation (e.g., seismites) this dynamic cycle is interrupted inducing full or partial preservation of the Fe-rich redox front. In such case, oxidation of dissolved Fe is interrupted and can be recycled in ferrous minerals, such as Fe monosulfides and amorphous phases with δ56Fe values down to − 1.7 ‰. These findings have significant implications for the recording of biogeochemical cycles in the geological past, the use of Fe isotopes in freshwater-lake sediments for paleoclimate studies, and the progress of our knowledge regarding the geochemistry of past oceans.
Fe isotopes measured above and below 8 cm depth (diamonds and circles, respectively) showing different correlation between the reduced and oxidized Fe phases (Feaca and Fehyam, respectively). Bars represent 1SD. Between 4 and 6 cm (black diamonds), the positive relation between both Fe pools is linked to the consumption of dissolved Fe during Fe oxidation. Below 8 cm, δ56Feaca dispersion and low δ56Fehyam suggest two end-members. Negative δ56Feaca are typical of pore waters with a high amount of dissolved Fe (likely resulting from reducing conditions). Near zero values suggest low Fe reduction or near complete precipitation of dissolved Fe as reduced Fe phases.
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