Ударные кратеры на земле диаметром больше 200 км – численное моделирование

Cover Page

Cite item

Full Text

Open Access Open Access
Restricted Access Access granted
Restricted Access Subscription Access

Abstract

Три самых больших ударных кратера, останки которых найдены на Земле к настоящему времени, имели сразу после образования диаметры около 200 км. Поиски следов ударных структур большего размера продолжаются. В данной работе приводятся результаты численного моделирования процесса образования земных ударных кратеров большего, чем уже найденные, размера. Показано, что предполагаемый геотермический градиент существенно влияет на начальную геометрию области ударного расплава, что может облегчить поиски останков глубоко эродированных древних ударных структур.

Full Text

Restricted Access

About the authors

Б. А. Иванов

Институт динамики геосфер им. М.А. Садовского РАН

Author for correspondence.
Email: boris_a_ivanov@mail.ru
Russian Federation, Москва

References

  1. Иванов Б.А. Моделирование крупнейших земных метеоритных кратеров // Астрон. вестн. 2005. Т. 39. С. 1–31. (Ivanov B.A. Numerical modeling of the largest terrestrial meteorite craters // Sol. Syst. Res. 2005. V. 39. P. 381–409.)
  2. Попов Ю.А., Певзнер С.Л., Пименов В.П., Ромушкевич Р.А. Певзнер С.Л. Геотермические характеристики разреза СГ-3 // Кольская сверхглубокая. Научные результаты и опыт исследований / Ред. Лаверов Н.П., Орлов В.П. М.: МФ ТЕХНОНЕФТЕГАЗ, 1998. С. 176–190.
  3. Akimoto S.-i., Komada E., Kushiro I. Effect of pressure on the melting of olivine and spinel polymorph of Fe2SiO4 // J. Geophys. Res.1967. V. 72. №2. P. 679–686. https://doi.org/10.1029/JZ072i002p00679.
  4. Allen N.H., Nakajima M., Wünnemann K., Helhoski S., Trail D. A revision of the formation conditions of the Vredefort crate // J. Geophys. Res.: Planets. 2022. V. 127. № 8. id. e2022JE007186.
  5. Allibert L., Landeau M., Röhlen R., Maller A., Nakajima M., Wünnemann K. Planetary impacts: scaling of crater depth from subsonic to supersonic conditions // J. Geophys. Res.: Planets. 2023. V. 128. № 8. id. e2023JE007823.
  6. Artemieva I.M., Shulgin A. Making and altering the crust: A global perspective on crustal structure and evolution // Earth and Planet. Sci. Lett. 2019. V. 512. P. 8–16.
  7. Baker D.M.H., Head J.W., Collins G.S., Potter R.W.K. The formation of peak-ring basins: Working hypotheses and path forward in using observations to constrain models of impact-basin formation // Icarus. 2016. V. 273. P. 146–163.
  8. Benz W., Cameron A.G.W., Melosh H.J. The origin of the Moon and the single-impact hypothesis III // Icarus. 1989. V. 81. № 1. P. 113–131.
  9. Boettcher A.L., Wyllie P.J. Melting of granite with excess water to 30 kilobars pressure // J. Geol. 1968. V. 76. № 2. P. 235–244.
  10. Bottke W.F., Norman M.D. The late heavy bombardment // Ann.l Rev. Earth and Planet. Sci. 2017. V. 45. P. 619–647.
  11. Bottke W.F., Vokrouhlicky D., Ghent B., Mazrouei S., Robbins S., Marchi S. On asteroid impacts, crater scaling laws, and a proposed younger surface age for Venus // Lunar and Planet. Sci. Conf. 47. 2016. Abs. № 2036.
  12. Cammarano F., Guerri M. Global thermal models of the lithosphere // Geophys. J. Internat. 2017. V. 210. № 1. P. 56–72.
  13. Cintala M.J., Grieve R.A.F. Scaling impact-melt and crater dimensions: Implications for the lunar cratering record // Meteorit. and Planet. Sci. 1998. V. 33. P. 889–912.
  14. Clauser C., Giese P., Huenges E., Kohl T., Lehmann H., Rybach L., Šafanda J., Wilhelm H., Windloff K., Zoth G. The thermal regime of the crystalline continental crust: Implications from the KTB // J. Geophys. Res.: Solid Earth. 1997. V. 102. № B8. P. 18417–18441.
  15. Cohen R.E. First-Principles Predictions of Elasticity and Phase Transitions in High Pressure SiO2 and Geophysical Implications // High-Pressure Research: Application to Earth and Planetary Sciences / Eds: Syono Y., Manghnani M.H. Tolyo/Washington DC: Terra Sci. Publ./Am. Geophys. Union, 1992. P. 425–431.
  16. Collins G.S. Numerical simulations of impact crater formation with dilatancy // J. Geophys. Res.: Planets. 2014. V. 119. P. 2600–2619.
  17. Collins G.S., Melosh H.J. Improvements to ANEOS for multiple phase transitions // Lunar Planet. Sci. Conf. 45. Woodland, TX. 2014. Abs. № 2664.
  18. Collins G.S., Melosh H.J., Ivanov B.A. Modeling damage and deformation in impact simulations // Meteorit. and Planet. Sci. V. 34 Supplement. 2004. V. 39(2). P. 217–231.
  19. Dell’Angelo L.N., Tullis J. Experimental deformation of partially melted granitic aggregates // J. Metamorph. Geol. 1988. V. 6. № 4. P. 495–515.
  20. Elbeshausen D., Wünnemann K., Collins G.S. Scaling of oblique impacts in frictional targets: Implications for crater size and formation mechanisms // Icarus. 2009. V. 204. P. 716–731.
  21. Furlong K.P., Chapman D.S. Heat flow, heat generation, and the thermal state of the lithosphere //Ann. Rev. Earth and Planet. Sci. 2013. V. 41. № 1. P. 385–410.
  22. Garde A.A., Ivanov B.A., McDonald I. Beyond Vredefort, Sudbury and Chicxulub //Meteorit. and Planet. Sci. Suppl. 2011. V. 74. Abs. № 5249.
  23. Garde A.A., McDonald I., Dyck B., Keulen N. Searching for giant, ancient impact structures on Earth: The Mesoarchaean Maniitsoq structure, West Greenland // Earth and Planet. Sci. Lett. 2012. V. 337. P. 197–210.
  24. Gibson R.L, Reimold W.U. The significance of the Vredefort Dome for the thermal and structural evolution of the Witwatersrand Basin, South Africa // Mineral. Pertol. 1999. V. 66. P. 5–23.
  25. Goetze C. High temperature rhelogy of Westerly granite // J. Geophys, Res. 1971. V. 76. № 5. P. 1223–1230.
  26. Grieve R., Therriault A. Vredefort, Sudbury, Chicxulub: Three of a kind? //Ann. Rev. Earth and Planet. Sci. 2000. V. 28. P. 305–338.
  27. Grieve R.A.F., Reny G., Gurov E.P., Ryabenko V.A. The melt rocks of the Boltysh impact crater, Ukraine, USSR // Contrib. Mineral. Petrol. 1987. V. 96. № 1. P. 56–62.
  28. Hasterok D., Gard M., Cox G., Hand M. A 4 Ga record of granitic heat production: Implications for geodynamic evolution and crustal composition of the early Earth // Precambr. Res. 2019. V. 331. id. 105375.
  29. Holland T., Powell R. Calculation of phase relations involving haplogranitic melts using an internally consistent thermodynamic dataset // J. Petrol. 2001. V. 42. № 4. P. 673–683.
  30. Holsapple K.A., Schmidt R.M. A material-strength model for apparent crater volume // Proc. Lunar and Planet. Sci. Conf. 10th. N.Y.: Pergamon Press, 1979. P. 2757–2777.
  31. Huber M.S., Kovaleva E., Rae A.S.P., Tisato N., Gulick S.P.S. Can Archean impact structures be discovered? A case study from Earth’s largest, most deeply eroded impact structure // J. Geophys. Res.: Planets. 2023. V. 128. № 8. id. e2022JE007721.
  32. Ivanov B.A., Artemieva N.A. Numerical modeling of the formation of large impact craters // Catastrophic Events and Mass Extinctions: Impact and Beyond, Geological Society of America. Spec. Pap. 356 / Eds: Koeberl C., MacLeod K.G. Boulder, Colorado: GSA, 2002. P. 619–630.
  33. Ivanov B.A., Deniem D., Neukum G. Implementation of dynamic strength models into 2D hydrocodes: Applications for atmospheric breakup and impact cratering. I // J. Impact Eng.1997. V. 20. № 1–5. P. 411–430.
  34. Ivanov B.A., Ford P.G. The depths of the largest impact craters on Venus (abstract) // Lunar and Planet. Sci. Conf. 24. 1993. P. 689–690.
  35. Ivanov B.A., Kamyshenkov D. Impact cratering: Scaling law and thermal softening // Lunar and Planet. Sci. Conf. 43. 2012. Abs. № 1407.
  36. Ivanov B.A., Melosh H.J. Impacts do not initiate volcanic eruptions: Eruptions close to the crater // Geology. 2003. V. 31. № 10. P. 869–872.
  37. Ivanov B.A., Melosh H.J., Pierazzo E. Basin-forming impacts: Reconnaissance modeling // GSA Special Papers 465 / Eds: Gibson R.L., Reimold W.U. Boulder, Colorado, USA: Geolog. Soc. Am. 2010. P. 29–49.
  38. Ivanov B.A., Turtle E.P. Modeling impact crater collapse: Acoustic fluidization implemented into a hydrocode // Lunar and Planet. Sci. Conf. 32. 2001. Abs. № 1284.
  39. Jennings E.S., Holland T.J.B. A simple thermodynamic model for melting of peridotite in the system NCFMASOCr // J. Petrol. 2015. V. 56. № 5. P. 869–892.
  40. Johnson B.C., Collins G.S., Minton D.A., Bowling T.J., Simonson B.M., Zuber M.T. Spherule layers, crater scaling laws, and the population of ancient terrestrial impactors // Icarus. 2016. V. 271. P. 350–359.
  41. Johnson B.C., Melosh H.J. Impact spherules as a record of an ancient heavy bombardment of Earth // Nature. 2012. V. 485. № 7396. P. 75–77.
  42. Karimi S., Dombard A.J. Studying lower crustal flow beneath Mead basin: Implications for the thermal history and rheology of Venus // Icarus. 2017. V. 282. P. 34–39.
  43. Katz R.F., Spiegelman M., Langmuir C.H. A new parameterization of hydrous mantle melting // Geochem., Geophys. Geosyst. 2003. V. 4. № 9. P. 1–19.
  44. Kukkonen I.T. Temperature and heat flow density in a thick cratonic lithosphere: The SVEKA transect, central Fennoscandian Shield // J. Geodyn. 1998. V. 26. № 1. P. 111–136.
  45. Kukkonen I.T., Clauser C. Simulation of heat transfer at the Kola deep-hole site: Implications for advection, heat refraction and palaeoclimatic effects // Geophys. J. Internat. 1994. V. 116. № 2. P. 409–420.
  46. Kumar P., Kind R., Priestley K., Dahl-Jensen T. Crustal structure of Iceland and Greenland from receiver function studies // J. Geophys. Res.: Solid Earth. 2007. V. 112. № B3. P. 1–19.
  47. Kurosawa K., Genda H. Effects of friction and plastic deformation in shock-comminuted damaged rocks on impact heating // Geophys. Res. Lett. 2018. V. 45. № 2. P. 620–626.
  48. Lana C., Gibson R.L., Kisters A.F.M., Reimold W.U. Archean crustal structure of the Kaapvaal craton, South Africa – evidence from the Vredefort dome // Earth and Planet. Sci. Lett. // 2003a. V. 206. № 1–2. P. 133–144.
  49. Lana C., Gibson R.L., Reimold W.U. Impact tectonics in the core of the Vredefort dome, South Africa: Implications for central uplift formation in very large impact structures // Meteorit. and Planet. Sci. 2003b. V. 38. P. 1093–1107.
  50. Lowe D.R., Byerly G.R. The terrestrial record of late heavy bombardment // New Astron. Rev. 2018. V. 81. P. 39–61.
  51. Luo S.-N., Ahrens T.J. Shock-induced superheating and melting curves of geophysically important minerals // Phys. Earth and Planet. Inter. 2004. V. 143–144. P. 369–386.
  52. McKinnon W.B., Zahnle K.J., Ivanov B.A., Melosh H.J. Cratering on Venus: Models and observations // Venus II. / Eds: Bougher S.W., Hunten D.M., Phillips R.J. Tucson, Arizona: Univ. Arizona Press, 1997. P. 969–1014.
  53. Melosh H.J. A hydrocode equation of state for SiO2 // Meteor. and Planet. Sci. 2007. V. 42. № 12. P. 2079–2098.
  54. Melosh H.J., Ivanov B.A. Impact crater collapse // Ann. Rev. Earth and Planet. Sci. 1999. V. 27. P. 385–415.
  55. Melosh H.J., Ivanov B.A. Slow impacts on strong targets bring on the heat // Geophys. Res. Lett. 2018. V. 45. № 6. P. 2597–2599.
  56. Miller C.F., McDowell S.M., Mapes R.W. Hot and cold granites? Implications of zircon saturation temperatures and preservation of inheritance // Geology. 2003. V. 31. № 6. P. 529–532.
  57. Morgan J.V., Gulick S.P.S., Bralower T., Chenot E., Christeson G., Claeys P., Cockell C., Collins G.S., Coolen M.J.L., Ferrière L., and 28 co-authors. The formation of peak rings in large impact craters // Science. 2016. V. 354. № 6314. P. 878–882.
  58. Nowka D., Wunnemann K., Collins G.S., Elbeshausen D. Scaling of impact crater formation on planetary surfaces // Eur. Planet. Sci. Congress. 2010. Abs. № 87. https://meetingorganizer.copernicus.org/EPSC2010/EPSC2010-87.pdf.
  59. Ohnaka M. A shear failure strength law of rock in the brittle-plastic transition regime // Geophys. Res. Lett. 1995. V. 22. № 1. P. 25–28.
  60. Plado J., Pesonen L. J., Puura V., Dressler B. O., Sharpton V. L. Effect of erosion on gravity and magnetic signatures of complex impact structures: Geophysical modeling and applications // Large meteorite impacts and planetary evolution; II. 1999. P. 229-239. Geological Society of America, Boulder, Colorado.
  61. Pichavant M., Weber C., Villaros A. Effect of anorthite on granite phase relations: Experimental data and models // Compt. Rend. Geosci. 2019. V. 351. № 8. P. 540–550.
  62. Pierazzo E., Artemieva N.A., Ivanov B.A. Starting conditions for hydrothermal systems underneath Martian craters: Hydrocode modeling // Spec. Paper 384: Large Meteorite Impacts III. 2005. P. 443–457.
  63. Pierazzo E., Vickery A.M., Melosh H.J. A reevaluation of impact melt production // Icarus. 1997. V. 127. P. 408–423.
  64. Poelchau M.H., Kenkmann T., Thoma K., Hoerth T., Dufresne A., SchńFer F. The MEMIN research unit: Scaling impact cratering experiments in porous sandstones // Meteorit. and Planet. Sci. 2013. V. 48. № 1. P. 8–22. https://doi.org/10.1111/maps.12016.
  65. Popov Y.A., Pevzner S.L., Pimenov V.P., Romushkevich R.A. New geothermal data from the Kola superdeep well SG-3 //Tectonophysics. 1999. V. 306. № 3. P. 345–366.
  66. Posiolova L.V., Lognonné P., Banerdt W.B., Clinton J., Collins G.S., Kawamura T., Ceylan S., Daubar I.J., Fernando B., Froment M., and 42 co-authors. Largest recent impact craters on Mars: Orbital imaging and surface seismic co-investigation // Science. 2022. V. 378. № 6618. P. 412–417.
  67. Potter R.W.K., Collins G.S., Kiefer W.S., McGovern P.J., Kring D.A. Constraining the size of the South Pole-Aitken basin impact // Icarus. 2012. V. 220. P. 730–743.
  68. Presnall D.C., Walter M.J. Melting of forsterite, Mg2SiO4, from 9.7 to 16.5 Gpa // J. Geophys, Res.: Solid Earth. 1993. V. 98. № B11. P. 19777–19783.
  69. Prieur N.C., Rolf T., Luther R., Wünnemann K., Xiao Z., Werner S.C. The effect of target properties on transient crater scaling for simple craters // J. Geophys. Res.: Planets. 2017. V. 122. P. 1704–1726.
  70. Puziewicz J., Czechowski L., Grad M., Majorowicz J., Pietranik A., Šafanda J. Crustal lithology vs. thermal state and Moho heat flow across the NE part of the European Variscan orogen: A case study from SW Poland // Int. J. Earth Sci. 2019. V. 108. № 2. P. 673–692.
  71. Reimold W.U., Gibson R.L. Geology and evolution of the Vredefort impact structure, South Africa // J. African Earth Sci.1996. V. 23. № 2. P. 125–162.
  72. Riller U., Poelchau M.H., Rae A.S.P., Schulte F.M., Collins G.S., Melosh H.J., Grieve R.A.F., Morgan J.V., Gulick S.P.S., Lofi J., Diaw A., McCall N., Kring D.A. IODP–ICDP Expedition 364 Science Party. Rock fluidization during peak-ring formation of large impact structures // Nature. 2018. V. 562. № 7728. P. 511–518.
  73. Rutter E.H., Neumann D.H.K. Experimental deformation of partially molten Westerly granite under fluid-absent conditions, with implications for the extraction of granitic magmas // J. Geophys. Res.: Solid Earth. 1995. V. 100. № B8. P. 15697–15715.
  74. Schaber G.G., Strom R.G., Moore H.J., Soderblom L.A., Kirk R.L., Chadwick D.J., Dawson D.D., Gaddis L.R., Boyce J.M., Russell J. Geology and distribution of impact craters on Venus: What are they telling us? // J. Geophys. Res.: Planets. 1992. V. 97. № E8. P. 13257–13301.
  75. Schmidt R.M. Preliminary scaling results for crater rim-crest diameter // Lunar and Planet. Sci. Conf. 18th. 1987. P. 878–879. https://articles.adsabs.harvard.edu/pdf/1987LPI....18..878S
  76. Schmidt R.M., Housen K.R. Some recent advances in the scaling of impact and explosion cratering // Int. J. Impact Eng. 1987. V. 5. № 1–4. P. 543–560.
  77. Schulz T., Koeberl C., Luguet A., van Acken D., Mohr-Westheide T., Ozdemir S., Reimold W.U. New constraints on the Paleoarchean meteorite bombardment of the Earth - Geochemistry and Re-Os isotope signatures of spherule layers in the BARB5 ICDP drill core from the Barberton Greenstone Belt, South Africa // Geochim. et Cosmochim. Acta. 2017. V. 211. P. 322–340.
  78. Schutt D.L., Lowry A.R., Buehler J.S. Moho temperature and mobility of lower crust in the western United States // Geology. 2018. V. 46. № 3. P. 219–222.
  79. Senft L.E., Stewart S.T. Modeling the morphological diversity of impact craters on icy satellites // Icarus. 2011. V. 214. № 1. P. 67–81.
  80. Simonson B.M., Glass B.B. Spherule layers records of ancient impacts // Ann. Rev. Earth and Planet. Sci. 2004. V. 32. P. 329–361.
  81. Steffen R., Strykowski G., Lund B. High-resolution Moho model for Greenland from EIGEN-6C4 gravity data // Tectonophys. 2017. V. 706–707. P. 206–220.
  82. Stixrude L., Lithgow-Bertelloni C. Thermodynamics of mantle minerals. II. Phase equilibria // Geophys. J. Int. 2011. V. 184. № 3. P. 1180–1213.
  83. Strom R.G., Schaber G.G., Dawsow D.D. The global resurfacing of Venus // J. Geophys. Res. 1994. V. 99. № E5. P. 10899–10926.
  84. Thompson S.L., Lauson H.S. Improvements in the Chart-D radiation hydrodynamic code. III: Revised analytical equation of state. Albuquerque, NM: Sandia Laboratories, 1972. SC-RR-71 0714. 119 p.
  85. Trowbridge A.J., Garde A.A., Melosh H.J., Andronicos C.L. iSALE numerical modeling of the Maniitsoq structure, West Greenland: A crustal-scale column of mechanical mixing reaching the Moho // Lunar and Planet. Sci. Conf. 48. 2017. Abs. № 2305. https://www.hou.usra.edu/meetings/lpsc2017/pdf/2305.pdf
  86. Valter A.A., Dobryansky Y.P., Lasarenko E.E., Tarasyuk V.K. Shock metamorphism of quartz and estimation of masses motion in the bases of Boltysh and Ilyinets astroblemes of the Ukranian Shield // Lunar and Planet. Sci. Conf. 13. 1982. Houston, TX. 819-820. https://articles.adsabs.harvard.edu/pdf/1982LPI....13..819V
  87. Werner S.C., Ivanov B.A. Exogenic dynamics, cratering, and surface ages (chapter 10.10) // Treatise on Geophysics (Second Edition) / Ed. Schubert G. Oxford: Elsevier, 2015. P. 327–365.
  88. Wunnemann K., Collins G.S., Melosh H.J. A strain-based porosity model for use in hydrocode simulations of impacts and implications for transient crater growth in porous targets // Icarus. 2006. V. 180. № 2. P. 514–527.
  89. Yakymchuk C., Kirkland C.L., Cavosie A.J., Szilas K., Hollis J., Gardiner N.J., Waterton P., Steenfelt A., Martin L. Stirred not shaken; critical evaluation of a proposed Archean meteorite impact in West Greenland // Earth and Planet. Sci. Lett. 2021. V. 557. id. 116730. (9 p.).

Supplementary files

Supplementary Files
Action
1. JATS XML
Download
2. Fig. 1. Top – image of the largest known impact crater on Venus, Mead, with a diameter of D = 270 km. Bottom – elevation profiles along three diameters (dashed, dotted, and solid curves) through Mead. The image and elevation profiles were constructed by the author using the publicly available JMars software (https://jmars.asu.edu) based on data from the Magellan spacecraft flight to Venus (https://www.jpl.nasa.gov/missions/magellan/).

Download (235KB)
Indexing metadata
3. Fig. 2. The Rachmaninoff impact crater (D ~ 300 km) on Mercury (top) and the elevation profile of the surface along the crater diameter (bottom). The inner crater has a depth of about 4.5 km. The image and elevation profiles were constructed by the author using the publicly available JMars software (https://jmars.asu.edu) based on the results of the Messenger spacecraft flight to Mercury (https://www.nasa.gov/mission_pages/messenger/main/index.html).

Download (332KB)
Indexing metadata
4. Fig. 3. The ancient impact crater Schröter (D ~ 300 km) on Mars (top) and the surface elevation profile along the crater diameter (bottom, solid line). The dotted line shows the profile of the younger and better preserved crater Lyot (D ~ 200 km). The image and elevation profiles were constructed by the author using the publicly available JMars software (https://jmars.asu.edu) based on the results of several NASA spacecraft flights to Mars (https://www.nasa.gov/mission_pages/mars/missions/index.html).

Download (405KB)
Indexing metadata
5. Fig. 4. Examples of geotherms with relatively low (1 – “cold” case) and relatively high (2 – “hot” case) inferred near-surface temperature gradients; 3 – liquidus and solidus for water-saturated granite (Boettcher, Wyllie, 1968), “G” – experimental point from (Goetze, 1971); 4 – the same for dry granite, “L” – liquidus points from (Dell’Angelo, Tullis, 1988), “W” – granite from (Rutter, Neumann, 1995). Dashed lines 4 approximate data for liquidus Tliq (K) = 1156 + 5.41 z (km) and granite solidus Tsol= 1020 + 5.41 z. The “K” signs illustrate the temperature gradient in the Kola superdeep borehole (Popov et al., 1999). 5 and 6 are the estimated solidus positions for the upper mantle (5 – fayalite, 6 – forsterite).

Download (103KB)
Indexing metadata
6. Fig. 5. Dimensionless diameter of the transition crater pDtc (equation (2)) as a function of the dimensionless quantity of the impactor p2 (equation (1)). For clarity, the upper horizontal axis shows the impactor diameter (km) for the earth's gravity and an impact velocity of U = 15 km/s. The experimental dependence for dry sand (lower dotted line) is taken from (Schmidt, Housen, 1987). The approximation of the calculated data for low-velocity impacts (U = 5 km/s) is shown by long dashes (1). The scaling law for a target without porosity is shown by solid curve 4. The approach of the calculated points to line 4 at high impact velocities is shown by lines 2 (impact velocity U = 20 km/s) and 3 (U = 30 km/s). Calculated points 5–9 are taken from the results of modeling for homogeneous targets with dry friction and thermal softening (Ivanov, Kamyshenkov, 2012). Calculations with a friction coefficient of 0.6 for U = 5 km/s: 5 – spherical impactor; 6 – elliptical impactor with a thickness of half the horizontal diameter; 7 – friction 0.6, ANEOS-quartzite target (Melosh, 2007), U = 20 km/s; 8 – friction 0.6, target – CaO (lime), U = 20 km/s; 9 – the same as 8, but for U = 30 km/s; 10 – this work.

Download (137KB)
Indexing metadata
7. Fig. 6. Calculated points for the depth of the transition crater in a homogeneous target with dry friction (Ivanov, Kamyshenkov, 2012) in comparison with the results of this work. The same icons are used as in Fig. 5. 1 - generalized dependence on the scale of the depth of the transition crater in a homogeneous target without strength (Schmidt, Housen, 1987). 2 - calculated dependence for low-velocity impacts in a target with dry friction (Ivanov, Kamyshenkov, 2012). 3 - generalized experimental dependence of the depth of craters in dry sand (Schmidt, Housen, 1987).

Download (84KB)
Indexing metadata
8. Fig. 7. Deformation and displacement of material in the central part of a model crater of the scale of the Vrøderfort crater. Distances along the axes are given in km. The time after impact is indicated above each figure.

Download (342KB)
Indexing metadata
9. Fig. 8. The final (~18 min after impact) cross-section of the model crater for the impactor twice as large (relative to the Vredefort crater impactor) (model V × 2, Dpr = 28 km, U = 15 km/s), calculated without using the AF model (acoustic fluidization model) in the mantle (a) and using this model (b). The position of the impact melt is marked in pink. Other color variations reflect different levels of rock damage (Collins et al., 2004). Horizontal and vertical distances are in km.

Download (355KB)
Indexing metadata
10. Fig. 9. The final (~18 min after impact) cross-section of the model crater for a quadruple (relative to the Vredefort impactor) impactor diameter (labeled 4 × V, Dpr = 57 km, U = 15 km/s), calculated without using the acoustic fluidization model for the mantle material (a) and using this model (b). Other color variations reflect different levels of rock damage (Collins et al., 2004). Horizontal and vertical distances are in km.

Download (341KB)
Indexing metadata
11. Fig. 10. Profiles of model craters for the 2 × V (a) and 4 × V (b) variants with a large vertical magnification to show the relatively shallow depths (~1.5 and ~3 km, respectively) of the final craters with apparent diameters of ~300 and ~500 km. Small divisions on the vertical axis correspond to the sizes of the calculation cells ∆x = 0.7 km (2 × V variant) and ∆x = 1.4 km (4 × V variant). The profiles in panels (a) and (b) correspond to calculations using the acoustic fluidization model in the mantle (1) and without it (2).

Download (104KB)
Indexing metadata
12. Fig. 11. Impact melt volume estimates for known terrestrial meteorite craters from (Cintala, Grieve, 1998): 1 – observations, 2 – maximum estimates, 3 – model results of the present work. Solid and dotted trend lines are described in the text.

Download (97KB)
Indexing metadata

Copyright (c) 2024 The Russian Academy of Sciences