Geochemistry, mineralogy, and magnetism of impact-related rocks. Геохимия, минералогия и магнетизм импактных пород.

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The importance of impacts in shaping the Earth’s history has been appreciated relatively late in the Earth sciences. But at the moment the studies of impact structures and related rocks is a vibrant research field combining the efforts of geologists, geochemists, geophysicists, physical modelers, etc. Impact studies have a number of goals such as modeling of impact events, determining the parameters of the impactor and the energy of explosions; clarifying the paleogeographic conditions in the impact area and its effect on the formation of the impact crater. Impact-related rocks, or impactites, are the product of hypervelocity, high-temperature and high-pressure processes during a shock event, and their properties are the clues to reconstruct the conditions during the impact. Impactites then undergo regional metamorphic processes which also leave a trace on impactite properties. Throughout their lifetime, impactites are subject to redox reactions involving polyvalent elements, primarily iron. Therefore, a comprehensive study of iron-containing minerals in impactites helps to understand the redox conditions that took place during the collisions of cosmic bodies with the Earth. On the other hand, impact melts can serve as a model for understanding the processes of ore mineralization, which is of interest both for exploration geology and for solving fundamental problems in the solid Earth physics, e.g., for paleo- and rock magnetic studies.Zhamanshin impact crater (48°24′N 60°58′E) is located in Kazakhstan, 40 km southwest of the Yrghyz town. Zhamanshin structure dated at 0.9 ± 0.1 My [Florensky P. V., and A. I. Dabizha, The meteorite crater Zhamanshin, Moscow, Nauka, 1980. (in Russian)], has the internal diameter about 5-6 km and shows many features that make it a unique research object. It is perfectly expressed in a landscape as a rounded depression with a flat bottom and gentle slopes. The internal structure of the crater was revealed from geophysical data, drilling operations and surface observations during Soviet period in 1970-80th. Impactites of several types are widely exposed including the most common “zhamanshinites” – bombs and fragments thereof up to several dozens of cm in size – and more rare varieties of “irghizites” and “microirghizites”, black colored glass fraction of a mm to several cm in size. These rocks are of particular interest since they are considered the highest-temperature impact product, possibly a variety of tektites. Tagamites (impact melts formed in situ) and suevites (impact breccia) are also exposed to a limited extent.Information on envisaged synergies between FUB and SPSUThe joint research group of the FUB- SPSU will combine experience in fields of rock magnetism, petrology and geochemistry, analytical capabilities and collections of relevant samples to conduct an in-depth study of impact-related rocks of Zhamanshin structure.The results will be published in peer-reviewed scientific journals. With a successful publication record and proven methodology, the joint FUB- SPSU research team will apply for DFG-RFBR research funding or similar programs.Level of concreteness of future joint research, incl. timeframe and information on funding programs and steps for developing a joint proposalThe project envisages fieldwork at the Zhamanshin crater, aimed to sample the impact-related and target rocks and to perform a detailed magnetic survey of the crater. The magnetic survey will clarify the areas of possible exposure of tagamites and suevites. Collected samples including all types of impactites will be subject to advanced laboratory experiments to study their geochemistry, petrography and magnetic properties, with an ultimate goal to elucidate a genetic relationship between impact-related and target rocks. This will serve as a starting point for creating a new map of the impactite exposure in the Zhamanshin structure providing necessary information to model the impact event and elucidate the impactor parameters.Compatibility with the FUB/SPSU research profiles (interdisciplinary nature, excellence of project leaders, scope of the fields/labs represented in the proposed activity)The proposed research makes an emphasis on the integrated approach involving geological, mineralogical, and rock magnetic data to study the genesis and geological evolution of impact-related rocks. This approach will be made possible with close cooperation of SPSU and FUB research groups and is squarely based on the existing analytical, methodological and scientific capabilities of each group.The SPbSU team has an extensive fieldwork experience including impact structures:—Kara, Nenets AO, Russia (supported by SPSU funding, project 11.42.504.2011, PI Dr. E. Sergienko). A collection of suevites is available, about 100 samples;—Jänisjärvi, Karelia, Russia (supported by SPSU funding, project 11.42.502.2013, PI Dr. E. Sergienko). A collection of tagamites is available, about 30 samples: —Zhamanshin, Aqtobe oblast’, Kazakhstan (supported by Russian Foundation for Basic Research, project 18-05-00626, , PI Dr. P. Kharitonskii). A representative collection of irghizites and zhamanshinites and a pilot collection of tagamites and suevites are available.Preliminary results on the magnetic properties of irghisites and zhamanshinites have been reported at the 81st Annual Meeting of The Meteoritical Society, Moscow, July 2018, and published in [Starunov V.A., A. Kosterov, E.S. Sergienko, S.Yu. Yanson, et al. (2019). Magnetic properties of tektite-like impact glasses from Zhamanshin Astrobleme, Kazakhstan. In: Nurgaliev D., Shcherbakov V., Kosterov A., Spassov S. (eds). Recent Advances in Rock Magnetism, Environmental Magnetism and Paleomagnetism. Springer Cham., pp. 445-465]. Of particular interest is a first finding of crystalline up to 20-30 µm iron-bearing inclusions in irghizites reported at XXVII Russian conference on electron microscopy, Chernogolovka, 28-30 August 2018 [E.S. Sergienko, S.Yu. Yanson, et al. Microinclusions in irghizites, Abstracts of XXVII Russian conference on electron microscopy, Chernogolovka, 28-30 August 2018, V. 2., pp. 201-202 (in Russian) https://www.crys.ras.ru/document/RCEM-2018/RCEM-2018_abstracts_volume_2_(conference).pdf].Members of the SPSU research team have extensive experience in fields of mineralogy and rock magnetism, particularly at cryogenic temperatures. This includes studies on the manifestation of the Verwey phase transition in the magnetic properties of magnetite particles of various size and stoichiometry [Kosterov, A. (2001), Earth. Planet. Sci. Lett., 186, 245-253; Kosterov, A. (2002), Geophys. J. Int., 149, 796-804; Kosterov, A. (2003), Geophys. J. Int., 154, 58-71; Kosterov, A. and Fabian, K. (2008), Geophys. J. Int., 174, 93-106], low-temperature magnetic properties of volcanic rocks [Kosterov, A. (2001), Earth Planets Space, 53, 883-892; Kosterov A., et al. (2009) Earth Planets Space, 61, 133-142; Kosterov, A., et al. (2018), Izvestiya, Physics of the Solid Earth, 54, 134-149], magnetic sulphide phases found in meteorites, such as troilite, daubreelite, alabandite [Kohout T., et al. (2007), Earth. Planet. Sci. Lett., 261, 143-151; Kohout T., et al. (2010), Icarus, 208, 955-962; Kohout T., et al. (2013), Am. Min., 98, 1550-1556]. In a recent study, low-temperature magnetometry has been successfully applied to determine the nature of carriers of natural remanent magnetization in impact melts of the Jänisjärvi astrobleme, Karelia [Sergienko, E.S., et al. (2017), Geophys. J. Int., 209, 1080-1094].The FUB participants are part of an expert team on the physics, petrology and geochemistry on impact cratering. The general approach is to combine field work, experiments and numerical modelling to improve the quantitative understanding of the physicochemical processes during hypervelocity impacts. This includes the petrogenesis of impact melts and impact melt-bearing breccias, so called suevites. Some selected references are: Artemieva N. A., Wünnemann K., Krien F., Reimold W. U., Stöffler D. (2013), Meteoritics and Planetary Science 48(4), 590-627. Hamann, C., Fazio, A., Ebert, M., Hecht, L., Wirth, R., Folco, L., Deutsch, A. and Reimold, W. U. (2018), Meteoritics & Planetary Science, 53 (8), 1594–1632. https://doi:10.1111/maps.12907; Hamann, C., R. Luther, M. Ebert, L. Hecht, A. Deutsch, K. Wünnemann, S. Schäffer, J. Osterholz, and B. Lexow (2016), Geophys. Res. Lett., 43, 10,602–10,610, doi:10.1002/2016GL071050.Kowitz A., Güldemeister N., Reimold W. U., Schmitt R. T., Wünnemann K. (2013), Earth and Planetary Science 384, 17-26.Luther, R. , Zhu, M. , Collins, G., Wünnemann, K. (2018), Meteoritics & Planetary Science 53(8), 1705-1732. doi:10.1111/maps.13143Moreau, J.-G., Kohout, T., Wünnemann, K., (2018), Physics of Earth and Planetary Interiors 281, 25-38.Schultze, D., Jourdan, F., Hecht, L., Reimold, W.U., Schmitt, R.-T. (2016), Meteoritics & Planetary Science, 51, 323–350, doi:10.1111/maps.12593.Siegert, S., and Hecht, L. (2018). Meteoritics & Planetary Science (early view). https://doi.org/10.1111/maps.13210Wünneman K., Collins G.S., Osinski G.R.(2008), Earth and Planetary Science Letters 269, 529-538.Hecht, L., Reimold, W.U., Sherlock, S., Tagle, R., Koeberl, C., Schmitt, R.T. (2008), Meteoritics & Planetary Science, 43, 1201-1218.Information on how the cooperation can be sustained beyond the initial seed money funding phaseIf successful, this collaboration can continue after the initial phase of funding. Based on the results, joint publications of the initial results are planned, and then the research team plans to prepare and submit a joint research proposal for DFG-RFBR or similar funding.  
AcronymJSMF 2019
StatusFinished
Effective start/end date22/03/1930/09/19