O2rigin (ERC funded)

The Earth’s upper mantle chalcophile and volatile record: Insights from peridotites and mantle sulfides

Dr. Maria Varas-Reus, Dr. Stephan König, Prof. Ronny Schönberg, Dr. Jean-Pierre Lorand (LPG Nantes, France), Dr. Toni Schulz (University of Vienna, Austria)

Like the other highly siderophile elements, the chalcophile and volatile ultra-trace elements selenium (Se) and tellurium (Te) show an excess abundance in the Earth’s mantle compared to abundances predicted by core-mantle differentiation. This excess has been commonly explained by the addition of late-accreted meteoritic material with possibly also volatiles such as water (Late Veneer). Concentrations of Se-Te and Se isotope systematics may thus help to assess these late accretion processes. To investigate these signatures of the Earth’s mantle we use combined Se-Te concentration and Se isotope measurements on Archean and post-Archean peridotites and their sulfide minerals.

Characterize the Earth’s modern mantle chalcophile and volatile signature from mantle-derived melts

MSc Aierken Yierpan, Dr. Stephan König, Dr. Jabrane Labidi (UCLA, USA), Prof. Ronny Schönberg

This subproject aims at constraining the Earth’s modern mantle chalcophile and volatile signature from the perspective of mid ocean ridge and ocean island basalts. For this Se-Te contents and Se isotope analyses will be performed on well characterized mafic rock suites and interpreted in the context of their trace element and radiogenic isotope signatures. This mantle signature will provide a baseline against which ancient chalcophile-volatile element and isotopic signatures, subduction-related recycling and the evolution of the continental crust can be investigated and compared. Part of the outcome will be useful to constrain how the Earth’s signature relates to that of chondritic meteorites that are considered building blocks of our planet.

Explore subduction recycling using chalcophile element systematics

MSc Timon Kurzawa, Dr. Stephan König, MSc Aierken Yierpan, Prof. Ronny Schönberg

This research project focuses on the geochemical behaviour of the chalcophile and moderately volatile elements Se and Te and the signature of Se isotopes in subduction zones. Basis for this investigation are island-arc volcanic rocks from various geodynamical settings worldwide for which a comprehensive trace element and radiogenic isotope dataset is generated. The results will contribute to understand the mechanisms of chalcophile-volatile element recycling at destructive plate boundaries and its role in the evolution of the Earth’s mantle-crust-atmosphere system.

Explore redox changes of the Earth’s surface from the mantle perspective

Dr. Stephan König, Dr. Maria Varas-Reus, Prof. Ronny Schönberg, Dr. Alexandro Cabral (Universidade Federal de Minas Gerais, Brasil)

Atmospheric redox evolution from the perspective of recycled sulfide inclusions in mantle rocks and minerals are investigated. In addition to their resistance and longevity, the relatively high chalcophile element concentrations in diamond-hosted sulfide inclusions render them promising target samples to record time-resolved oxygenation-related Se isotope variations. Some of the significant differences between S and Se isotope systematics might be useful here, such as the delayed oxidation of Se species compared to S, which may also delay subsequent reduction-related Se isotope fractionation in the geological record. Hence in addition to existing S isotope constraints, new Se isotope data on these minerals are explored to study the stepwise increase in atmospheric oxygenation to the present-day level and the subsequent recycling of these minerals from the mantle perspective.

The chalcophile and volatile signature of chondrites

Dr. Jabrane Labidi (UCLA, USA), Dr. Stephan König, Prof. Ronny Schönberg

Selenium isotope signatures of chondrites will contribute to assess the chalcophile-volatile record of solar system materials. Once the Se isotope record of the bulk silicate Earth is constrained, it may be compared to chondrites and their sulfides as potential material for Earth accretion, including late meteoritic additions following core-mantle differentiation (Late Veneer components) that may have contributed volatiles such as water. For this study, a representative selection of the main classes of chondritic meteorites with compositions from volatile-rich to volatile-depleted is investigated.