Foto: DFG Forschergruppe MEMIN
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Multidisciplinary Experimental and Modeling Impact Research Network

Impact cratering is a fundamental geologic process throughout the solar system. Understanding this process requires multi- and interdisciplinary research that includes studies of natural craters, laboratory experiments, and numerical simulations. Researchers at MfN are involved in a Multidisciplinary Experimental and Modelling Impact Research Network (MEMIN Forschergruppe) comprising geoscientists, physicists, and engineers who want to obtain new insights into impact crater formation on Earth and other planetary surfaces. Central to MEMIN are two-stage light gas guns that became available through the collaboration with the Fraunhofer Institute for High-Speed Dynamics, Ernst-Mach-Institute (EMI). The two-stage light gas guns enable the acceleration of iron, aluminium and meteoritic projectiles, 2-12 mm in diameter, to velocities of up to 7.8 km/s, to produce craters in the decimetre-range in solid rocks. Such a crater size has been previously not achieved at the laboratory scale and it allows for detailed spatial analyses. The cratering experiments on different target materials with different properties such as strength, porosity, water saturation and by the variation of the impact velocity and the projectile material the effect on cratering mechanics, shock effects, and projectile distribution is investigated. The work program includes (i) complete mineralogical-petrophysical, and mechanical characterization of the target prior to and after the experiment using, for example, state-of-the-art geophysical tools for meso-scale tomography and microstructural analyses at the nano-scale, (ii) stringent control of the impact experiment itself with newly developed in-situ real-time measurements of fracture propagation, stresses, crater growth and ejecta dynamics, and (iii) numerical modelling of the complete process. MEMIN is designed to yield a solid data base for validation and refining of numerical cratering models that allow for scaling of meso-scale observations to the size of natural craters.

Sub-Projects

Numerical Modeling of Impact Cratering Processes

Numerical modelling of impact processes plays a central role in the framework of the MEMIN research unit. The simulation of impacts provides insights into highly dynamic processes that are impossible or rather difficult with major technological efforts to measure.  With regard to the exploration natural craters  on Earth and other planetary surfaces computer models are the only possible approach to reconstruct the crater formation process.  The goal of this study is to improve the existing simulation software by implementing novel, more sophisticated material models that describe the behaviour of matter under extreme pressure, temperature and strain rate conditions. Besides model development validation and calibration using the laboratory experiments is crucial for realistic model predictions on crater size, ejecta distribution, damage and fracturing of rocks. Two different model types, so-called (1) “meso-scale” and (2) “macro-scale” models are employed:

  1. Meso-scale models enable to resolve heterogeneities in rocks on a meso-scale such as pores and grains. The models allow for a detailed analysis of modifications of the meso-scale structure as a consequence of shock wave loading, in other words, for example, how pores collapse and how it affects the shock pressure distribution.
  2. In macro-scale models the entire crater formation process is simulated. Results from meso-scale models are take into account for the macro-scale consequences. These models are directly comparable to observations from laboratory experiments with regard to crater size, ejecta distribution, and the extent of the damage zone. In addition seismic signals and the propagation of the shock wave can be recorded and compared with experimental measurements using acoustic sensory and pressure gauges.

By integrated meso- and macro-scale modelling and the calibration od material models by means of laboratory experiments it is possible to reconstruct the formation of natural craters in a size range of a few 100 meters to more than 1,000 kilometers.

Team:

Collaborators:

Selected Publications:

  • Wünnemann K., Zhu Meng-Hua, Stöffler D. 2015, Impacts into Quartz Sand: Crater Formation, Shock Metamorphism, and Ejecta Distribution in Laboratory Experiments and Numerical Models, Meteoritics & Planetary Science (in press).
  • Kowitz A. , Güldemeister N., Schmitt R. T., Reimold W. U., Wünnemann K.  2016. Revision and recalibration of existing shock classifications for quartzose rocks using low-shock pressure (2.5-20 GPa) recovery experiments and meso-scale numerical modeling. Meteoritics & Planetary Science, in press.
  • Güldemeister N., Wünnemann K. and Poelchau M. H. 2015. Scaling impact crater dimensions in cohesive rock by numerical modeling and laboratory experiments. Geological Society of America Special Papers 518: SPE518-02.
  • Moser D., Güldemeister N., Wünnemann K., Grosse C., 2013. Acoustic Emission Analysis of Experimental Impact Processes in Comparison to Ultrasound Measurements and Numerical Modeling. Journal of Acoustic Emission(JAE). Online Volumes 31, 50-66.
  • Kowitz A. , Güldemeister N., Reimold W. U., Schmitt R. T., Wünnemann K. , 2013. Diaplectic quartz glass and SiO2 melt experimentally generated at only 5 GPa shock pressure in porous sandstone: Laboratory observations and meso-scale numerical modeling. Earth and Planetary Science Letters 384:17-26, http://dx.doi.org/10.1016/j.epsl.2013.09.021.
  • Güldemeister N., Durr N., Wünnemann K., Hiermaier S., 2013. Propagation of impact-induced shock waves in porous sandstone using mesoscale modeling. Meteoritics & Planetary Science 48: 115-133.
  • Durr N., Sauer M., Hiermaier S., Güldemeister N., Wünnemann K. 2013. Mesoscale investigation of shock wave effects in dry and water-saturated sandstone. Proceedings of the 12th Hypervelocity Impact Symposium, Procedia Engineering 58: 289–298.
  • Buhl E., Kowitz A., Elbeshausen D., Sommer F., Dresen G., Poelchau M. H., Reimold W. U., Schmitt R. T., Kenkmann T. 2013. Particle size distribution and strain rate attenuation in hyper-velocity impact and shock recovery experiments. Journal of Structural Geology, Volume 56, November 2013, Pages 20-33, ISSN 0191-8141,  http://dx.doi.org/10.1016/j.jsg.2013.08.007.
  • Wünnemann K., Nowka D., Collins G.S., Elbeshausen D., Bierhaus M. 2011. Scaling of impact crater formation on planetary surfaces – insights from numerical modeling. Proceedings of the 11th Hypervelocity Impact Symposium, Fraunhofer Verlag 120: 1-16.
  • Kenkmann T., Kowitz A., Wünnemann K., Behner T., Schäfer F., Thoma K., Deutsch A. 2011. Experimental impact cratering in sandstone: the effect of pore fluids. Proceedings of 11th Hypervelocity Impact Symposium, Fraunhofer Verlag 97: 64-74.
  • Kenkmann T., Wünnemann K., Deutsch A., Poelchau M. H., Schäfer F, Thoma K. 2011. Impact cratering in sandstone: The MEMIN pilot study on the effect of pore water. Meteoritics & Planetary Science 46: 890–902.

Low-grade shock metamorphism of quartz

Within the Multidisciplinary Experimental and Modelling Impact Research Network (MEMIN) this project is focused on low-grade shock metamorphism in porous and wet sedimentary rocks, specifically on quartz, one of the most abundant minerals in the Earth´s upper crust and the most important mineral for shock barometry. The aims are (i) to study the influence of porosity and water saturation on the development of shock effects and of progressive shock metamorphism, (ii) the shock pressure calibration of these effects, especially in the range 5 to 15 GPa, to improve the shock classification scheme, (iii) to analyze the shock-induced melting, and (iv) to elucidate the formation of planar deformation features in quartz and SiO2 high-pressure phases. Starting point for the investigations are shock recovery experiment with dry and water-saturated sandstone, and with quartzite. The evaluation of the shocked samples uses mineralogical methods, which are combined with numerical modeling (Project Numerical Modeling of Impact Cratering Processes) for the interpretation of the results.

Team:

Collaborators:

Selected Publications:

  • Kowitz, A., Güldemeister, N., Reimold, W. U., Schmitt, R. T. and Wünnemann, K. 2013. Diaplectic quartz glass and SiO2 melt experimentally generated at only 5 GPa shock pressure in porous sandstone: Laboratory observations and meso-scale numerical modeling. Earth and Planetary Science 384, 17-26.
  • Kowitz, A., Schmitt, R. T., Reimold, W. U. and Hornemann, U. 2013. The first MEMIN shock recovery experiments at low shock pressure (5-12.5 GPa) with dry, porous sandstone. Meteoritics and Planetary Science 48, 99-114.
  • Buhl, E., Kowitz, A., Elbeshausen, D., Sommer, F., Dresen, G., Poelchau, M. H., Reimold, W. U., Schmitt, R. T. and Kenkmann, T. 2013 Particle size distribution and strain rate attenuation in hypervelocity impact and shock recovery experiments. Journal of Structural Geology 56, 20-33.
  • Kowitz, A., Güldemeister, N., Schmitt, R. T., Reimold, W. U., Wünnemann, K. and Holzwarth, A. (2016) Revision of existing shock classifications for quartzose rocks using low shock pressure recovery experiments (2.5-20 GPa) and meso-scale numerical modeling. Meteoritics and Planetary Science, accepted.
     

On the fate of the projectile in impact cratering experiments

In this subproject we investigate the chemical and physical interaction between projectile and target materials during hypervelocity impacts. Using a combination of conventional impact experiments, innovative laser-melting experiments, and petrological investigations of natural terrestrial impactites we try to better understand processes and products of impact melting and vaporization. We specifically focus on the fate of carbonates upon impact and investigate whether melting or decomposition of carbonates occur under high pressure and temperaturs. To this end we combine results obtained from state-of-the-art impact experiments and innovative laser-melting experiment with observations from natural impact melt rocks and glasses.

Team:

Collaborators:

Selected Publications and conference contributions:

  • Hamann C., Stöffler D., and Reimold W. U. Interaction of aluminum projectiles with quartz sand in impact experiments: formation of khatyrkite (CuAl2) and reduction of SiO2 to Si. Geochimica et Cosmochimica Acta, in press.
  • Van Roosbroeck N., Hamann C., McKibbin S., Greshake A., Wirth R., Pittarello L., Hecht L., Claeys P., and Debaille V. Immiscible silicate liquids and phosphoran olivine in Netschaëvo IIE silicate: analogue for planetesimal core–mantle boundaries. Geochimica et Cosmochimica Acta, in press.
  • Ebert M., Hamann C., Hecht L. Laser-induced melting experiments: simulation of short-term high-temperature impact processes. Meteoritics & Planetary Science, in press.
  • Schultze D.S., Jourdan F., Hecht L., Reimold W.U., Schmitt R.-T. 2016. Tenoumer impact crater, Mauritania: Impact melt genesis from a lithologically diverse target. Meteoritics & Planetary Science 51, 323-350.
  • Ebert M., Hecht L., Deutsch A., Kenkmann T., Wirth R., and Berndt J. 2014. Geochemical processes between steel projectiles and silica-rich targets in hypervelocity impact experiments. Geochimica et Cosmochimica Acta 133, 257–279.
  • Ebert M., Hecht L., Deutsch A., and Kenkmann T. 2013. Chemical modification of projectile residues in a MEMIN cratering experiment. Meteoritics & Planetary Science 48, 134–149.
  • Hamann C., Hecht L., Ebert M., and Wirth R. 2013. Chemical projectile–target interaction and liquid immiscibility in impact glass from the Wabar craters, Saudi Arabia. Geochimica et Cosmochimica Acta 121, 291–310.

Further Details

Funding: Deutsche Forschungsgemeinschaft (German Research Foundation, DFG)

Duration: since 2009

Project Website: http://www.memin.de