Depositional record of pristine impactites and traces of the projectile in El'gygytgyn crater.

The International Continental Scientific Drilling Program drilled ~225.3 m of lake sediments that are underlain by impact breccias to a final depth of ~517.3 m below the crater lake floor of the inner region of the ~3.6 Ma old, NE Siberian El'gygytgyn crater [1, 2, 3]. This continuous drill core section likely recoverd pristine impactites from a large (18 km Ø) terrestrial crater [e.g., 4]. A record of the response to shock metamorphism of the volcanic upper target rock succession [4, 5], impactite emplacement, and only minor alteration likely allow comparison to impacts on other terrestrial planets. The distribution of impactor traces in the continuous impactite section furthermore may validate previous reports of an achondritic (ureilite?) projectile at El'gygytgyn [6]. Impactor identification for El'gygytgyn could link a sub-recent "fossil" projectile to the present-day flux of meteoritic material to Earth.

[1] Melles et al. (2011) Scientific Drilling 11, 29-40. [2] Gurov et al. (1978) Dok. Akad. Nauk SSSR 240, 1407-1410. [3] Layer (2000) MAPS 35, 591-600. [4] Gurov et al. (2005) GSA Spec. Pap. 384, 1495-1508. [5] Glushkova & Smirnov (2005) in Ber. Polarforsch. Meeresforsch., 14-18. Institute for Geophysics and Geology, Leipzig. [6] Va'lter et al. (1982) Pisma Astr. Zh. 8, 115-120.