2. Current Research Situation and Scientific Achievements

 

A network of new university groups.

The Earth’s early evolution and the early solar system are topics featured by a number of strong research groups in Germany. Most of these groups are university-based. Notably, some permanent university appointments have been made in the past years that significantly increased the research strength in this field.

 

Scientific excellence.

The participating scientists have significantly advanced our understanding of fundamental processes involved in the early history of the Earth and the solar system, as documented by numerous publications in high impact journals such as Nature, Science, and the top Earth and Planetary Science journals (see reference list). The scientific excellence of many researchers involved is also documented by several junior and senior research prizes, such as Heisenberg scholarships, Emmy Noether awards, DMG-Victor-Moritz-Goldschmidt prizes, Leibniz prizes and ERC grants. The groups involved in this SPP initiative have made significant contributions to this topic by studying extraterrestrial samples and the oldest rocks available from the terrestrial rock record (see reference list). Disciplines that have been involved cover geo-cosmochemistry, mineralogy, experimental petrology, physical modelling, planetology and geobiological approaches.

 

Emerging analytical techniques.

Research groups in Germany have made important analytical contributions relevant to studying Earth’s early evolution. Many significant breakthroughs in the field were in fact triggered by such new technical developments, e.g., in mass spectrometry (high precision TIMS, Multicollector ICPMS, SIMS, multiple O/S gas mass spectrometers). Some of these techniques, for instance, permit stable/radiogenic isotope or trace element measurements at unprecedented precision, accuracy and spatial resolution. Over the past years the so-called “non-traditional” stable isotopes have emerged as an innovative tool to study processes in the early solar system as well as erosion processes, redox conditions or mass fluxes in the early oceans. New developments in mass spectrometry have improved the precision for isotope ratio measurements by nearly an order of magnitude, thus permitting the discrimination of potential planetary building blocks through nucleosynthetic anomalies or dating of planetary growth using short-lived chronometers. Another important tool is the application of noble gases and mass independent isotope fractionation effects (triple O and quadruple S) as tracer for the evolution of Earth’s ocean-atmosphere system. Microanalytical techniques such as Laser ICPMS, SIMS, Nano-SIMS, TEM, Raman spectroscopy or synchrotron x-ray tomography and fluorescence now permit measurements of geological and extraterrestrial materials at high spatial resolution down to the nm level. Further important applications are trace element or isotope studies on individual meteorite components or investigations on fluid and mineral inclusions in old terrestrial minerals such as zircons.

 

Emerging experimental and modelling techniques.

As the early terrestrial rock record becomes patchier with increasing age, laboratory experiments and physical modeling can provide crucial information on the formation and earliest evolution of the Earth. Physical applications include modeling of asteroid collisions and the growth of larger planetary bodies like the Earth. Other modeling approaches explore the early magma ocean and the geodynamics of early plate tectonics. Important experimental applications include the determination of element partition coefficients relevant to core formation, crystallization of a terrestrial magma ocean or formation of the first continental crust. Experimental studies across the interface between biology, geochemistry and geology allow investigating the role of microorganisms in the early oceans such as during formation of chemical sediments like Banded Iron Formations. Again, several German groups are involved in these research questions at an internationally highly visible level.

 

Key achievements.

Ten major, internationally highly visible scientific achievements of groups involved in this SPP proposal include:

• Systematic studies on isotopic and elemental anomalies in meteorites to identify potential building blocks of the Earth.
• A refined early solar system chronology from short- and long-lived nuclide systems.
• Experimental and isotopic studies on element fluxes during core formation and volatile addition during the late veneer.
• The age and composition of the Earth-Moon system.
• Composition of the first atmosphere and degassing of the early Earth.
• Participation in international field campaigns/drilling projects at Early Archean key localities such as Southwest Greenland, Northern Canada and South Africa.
• Providing new time constraints on the onset of plate tectonics on the early Earth.
• New genetic models and time constraints on the evolution of the Earth’s first crust.
• Evaluation of biological versus abiotic models for precipitation of Archean Banded Iron Formations (BIFs).
• Defining the time frame, causes and consequences of Earth’s surface oxygenation.