Séminaire ISTerre

Unearthing ancient DNA from sediment archives: a journey from fire to ice

mercredi 26 novembre 2025 - 11h00
Lucinda Duxbury - Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Australia
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Understanding how ecosystems have responded to past environmental changes is an important way we can contextualise the current climate crisis. Sedimentary archives can preserve nucleic acids over millions of years and thus represent a treasure trove of long-term records of past biodiversity. Despite this, the taphonomic processes governing their preservation in sediments are poorly understood. In this talk, I will discuss two well-preserved sedimentary ancient DNA records from opposite sides of the globe. The first comes from a small lake on Kangaroo Island/Karti, Australia, with a maximum depth of about one metre and high summer temperatures. Although conventional wisdom at the time suggested such a lake would be unfavourable to the preservation of DNA, we recovered sedimentary ancient DNA throughout the entire 7,000-year sequence. Our results helped to untangle local and regional signals of vegetation change in response to changes in climate, fire and people. The other record comes from an international collaborative effort to drill Arctic marine sediments down to 600 metres below the seafloor from water depths of over a kilometre. The expedition targeted sediments in the eastern Fram Strait, Arctic, with highly expanded deposition during past warm periods. We have so far successfully extracted sedimentary ancient DNA up to approximately half a million years old, including a high resolution record of marine ecosystem change from the transition into MIS 5e (~130-115 Ka), which by some estimates was the last time the Arctic was ice free in summer. Furthermore, we are attempting to extract DNA from 3-million-year-old sediment. In recent years, a link between the presence of certain clays and the preferential preservation of ancient DNA has been proposed. At ISTerre, I am conducting X-ray diffraction analysis to investigate the mineralogical properties of these Arctic sediments. We aim to link these results with indicators of DNA damage to interrogate the potential control of mineralogy on DNA preservation in the eastern Fram Strait.

Equipe organisatrice : Minéralogie

Salle Dolomieu, Maison des Géosciences, 38400 Saint Martin d'Hères

Informations de visio :

Stanislav Jelavic is inviting you to a scheduled Zoom meeting.

Topic : Unearthing ancient DNA from sediment archives : a journey from fire to ice
Time : Nov 26, 2025 11:00 AM Paris
Join Zoom Meeting
https://univ-grenoble-alpes-fr.zoom.us/j/94964887683?pwd=0ja2VFZQcgKhNhKkoyIgfDvFt4lLxF.1

“Minimalist seismology”: studying earthquakes with sparse instrumentation

jeudi 17 septembre 2026 - 11h00

Mathieu Causse - ISTerre

Equipe organisatrice : Organisation labo

Amphithéâtre Killian, Maison des Géosciences, 38400 Saint Martin d'Hères

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Stable‑to‑dynamic expansion of fault slipping area through fluid injection observed in laboratory experiments using a sub‑meter scale specimen

vendredi 18 septembre 2026 - 14h00

Takatoshi Ito  - Université de Tohoku, Japan

Equipe organisatrice : Mécanique des failles

Amphithéâtre Killian, Maison des Géosciences, 38400 Saint Martin d'Hères

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Tectonics, Mantle Dynamics and Coupled Lithosphere-Mantle-Core Evolution of Earth and Other Rocky Worlds

jeudi 24 septembre 2026 - 11h00

Paul Tackley - ETH Zurich

Equipe organisatrice : Grands Séminaires ISTerre

Amphithéâtre Killian, Maison des Géosciences, 38400 Saint Martin d'Hères

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Tectonics, Mantle Dynamics and Coupled Lithosphere-Mantle-Core Evolution of Earth and Other Rocky Worlds

jeudi 24 septembre 2026 - 11h00

Paul Tackley - ETH Zurich

Equipe organisatrice : Grands Séminaires ISTerre

Amphithéâtre Killian, Maison des Géosciences, 38400 Saint Martin d'Hères

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Apport des expériences analogiques pour la modélisation et le suivi en temps réel de la propagation du magma en profondeur : Exemple du Rift Est Africain

jeudi 1er octobre 2026 - 11h00

Virginie Pinel - ISTerre

Equipe organisatrice : Organisation labo

Amphithéâtre Killian, Maison des Géosciences, 38400 Saint Martin d'Hères

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A t-on encore besoin de plaques pour expliquer la tectonique de la vallée du Rhône et des Alpes Occidentales ?

vendredi 2 octobre 2026 - 11h00

philippe VERNANT - Geosciences Montpellier

Equipe organisatrice : Tectonique active et sismicité

Salle Dolomieu, Maison des Géosciences, 38400 Saint Martin d'Hères

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TBA

vendredi 2 octobre 2026 - 14h00

Hugo Boulze - 

Equipe organisatrice : Cycle sismique et déformations transitoires

Amphithéâtre Killian, Maison des Géosciences, 38400 Saint Martin d'Hères

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TBA

vendredi 9 octobre 2026 - 11h00

Eric Beaucé - ISTerre

Equipe organisatrice : Cycle sismique et déformations transitoires

Salle Dolomieu, Maison des Géosciences, 38400 Saint Martin d'Hères

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TBA

vendredi 20 novembre 2026 - 11h00

Farzaneh Mohammadi - ENS Paris

Equipe organisatrice : Cycle sismique et déformations transitoires

Amphithéâtre Killian, Maison des Géosciences, 38400 Saint Martin d'Hères

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