19 Jun 2017

Publication: Brief oxygenation event during the Cambrian explosion linked to a reorganization of the marine biogeochemical cycles – might be animal-driven

A recent article published in Geochemical Perspectives Letters, we present carbon, sulfur and uranium isotope data from Siberian limestone sections straddling the Cambrian Stage 2–3 boundary (Tommotian-Atdabanian) 521–519 million years ago. We discovered a new type of oceanic event where enhanced marine organic carbon and pyrite burial coincides with a more oxygenated ocean state. The event was relative brief, […]

20 Apr 2017

Publication: Molybdenum re-dissolves and re-precipitates in euxinic lake sediments

In a paper published in Chemical Geology entitled: “Molybdenum isotope fractionation and speciation in a euxinic lake—Testing ways to discern isotope fractionation processes in a sulfidic setting”, we compare molybdenum isotope and speciation data from lake sediments deposited under euxinic (anoxic and sulfidic) waters. We conclude that the chemical Mo species present in sediments did not […]

26 Jan 2017

Molybdenum review: The answer is 42

Molybdenum is element number 42 in the periodic table. Although, this element is a trace constituent in the Earth and life, it currently deserves a lot of attention. With Brian Kendall and Ariel Anbar, I have written a review that brings the latest update on the various aspects of molybdenum isotopes and their current use in geochemistry, cosmochemistry and […]

21 Dec 2016

Publication: Molybdenum interacts directly with organic matter in sulfidic environments

Molybdenum is one of the most powerful elements used to track hydrogen sulfide and oxygen in the ocean from the geological record. Still, we have an incomplete understanding of the chemical removal pathway between ocean and sediments.  Sediments deposited under anoxic and sulfidic waters display tight correlations between their contents of molybdenum (Mo) and total organic matter  (TOC). Yet, association does not mean causation. Instead, […]

15 Aug 2016

Article in PNAS: Humble moss created modern O2 levels

In a new modeling study led by Tim Lenton from University of Exeter, we found that the earliest land plants caused atmospheric O2 levels to increase above the “fire limit”, where stuff will ignite and burn. This result fits nicely with available geochemical and paleontological evidence, but previous theoretical models predicted either an earlier or a later rise of […]

30 Apr 2016

New release, Evidence for high pO2

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April 20 Evidence for high pO2 ~1400 Myrs, communication in PNAS. pdf