THE SAARLOUIS SEMI CRATER STRUCTURE: NOTABLE INSIGHT INTO THE SAARLAND (GERMANY) METEORITE IMPACT EVENT ACHIEVED Kord Ernstson1, Werner Müller2, Andreas Gawlik-Wagner3 1Faculty of Philosophy I, University of Wurzburg,̈ Germany 266809 Nalbach, Germany , 366763 Dillingen, Germany
The Nalbach impactite strewn field and crater The Saarlouis semi crater The Saarlouis semi crater - meteorite impact evidence
Nalbach crater clast size grading and alignment vesicular iron - meltrock clast indicate flow texture Suevite breccia from A 8 Nalbach the crater rim. impact field Dillingen Berlin
50 µm Köln Wallerfangen A 8 shock PDF in Saarland feldspar and Saarlouis impact 100 km semi crater quartz Saarlouis 50 µm
Altforweiler France A 620 Suevite, SEM-EDS: iron-metallic spherules in basaltic-andesitic melt rock clasts. München 1 km native iron layered electron images spherule Location map for the Saarland meteorite impact event (to the with carbon image The Saarlouis semi crater: The rim wall crest (+) is forming a filaments left): the Nalbach impactite strewn field established a few years segment of a nearly perfect 2.3 km-diameter circle (to the left). ago and the recently discovered Saarlouis semi impact crater (to Geological map; simplified from Geoportal.saarland.de (to the right). the right). Fe, 200 µm O Shock metamorphism, melt rocks and glasses in native iron Fe spherules C the Nalbach impactite strewn field and thin sections, photomicrographs; crossed polarizers (XX) and plane light (II). andalusite re- crystallization (?) 500 µm 500 µm 100 µm mostly anorthite, also orthoclase, Mn-Mg pyroxene, andalusite? 100 µm O quartz, Mg C glass-filled open Ca S K fractures Quartzite cobble completely transferred to diaplectic glass; XX and II.
Multiple sets of planar fractures (PF) and P Al Si spots of diaplectic glass in quartz; XX.
150 µm 150 µm Ti Mn Fe
q q
Planar deformatiom features (PDF) in quartz; XX. fractured quartz Diaplectic sanidine crystals in diaplectic grains quartzite glass; XX and II. almost pulverized
100 µm q
100 µm after Google Earth 2 cm 100 µm cut face q 1 mm Ballen structures in silica; XX and II. Strongly kinked mica (XX) and "toasted" quartz (II). Strong 1 cm Melt rock matrix with moderately shocked quartz 200 µm Map of shaded relief of the Digital Terrain Model (DTM) and profiles grains (q; and photomicrographs to the right) having shock meta- obviously survived impact shock melting. Thin section across the rim wall. For comparison other typical crater profiles are Impact melt rock excavated photomicrographs, crossed polarizers. morphism shown. DTM data from LVGL Saarland. during gas pipeline burying. Most larger quartz grains show multiple sets of planar fractures as in proof (PF) and fainter planar deformation features (PDF).Thin section photomicrographs, crossed polarizers; field widths 150 µm. 400 µm 100 µm of meteorite Two quartz grains with Ballen structures merging in cristobalite and Multiple sets (white) of open tensile, glass-filled impact. tridymite; XX and II. planar features in mica. spallation fractures The Saarland impact event - discussion and conclusions Impact glasses in the Nalbach strewn field -- The strong and widely distributed shock metamorphism, the impact glasses, the impact mm scale melt rocks and a suevite polymictic breccia establish a proven meteorite impact event near the German-French frontier. The discovery goes back to field observations and sampling by the coauthors W. M. and A. G. 1 cm -- So far two impact craters with diameters of 200 m (Nalbach) and 2.3 km (Saarlouis) and a classically countoured rim wall have been identified. Both are in part eroded to feature rather semi craters. Digital Terrain Model (DGM 1): The 200 m-diameter (rim crest) Nalbach crater. -- The widely distributed near-surface strongly shocked impactites are considered ejected 1 cm 2 cm 200 µm material or/and restored by fluvial transport. -- Impactites at 2 m depth excavated together with human bones from below the Impact melt rocks in the Nalbach strewn field foundations of a Romanesque church in Nalbach exclude any anthropogenic/industrial products. 1 cm -- SEM-EDS analyses of suevite composition and formation remain puzzling and require more detailed studies of the in part igneous impact target not exposed in the investigated 2 cm bone splinters in glass area.
1 cm 1 cm 2 cm -- According to the Lower Terrace sediments at the bottom of the Saarlouis semi crater the age of the impact event is Pleistocene or older.
open spallation fissures filled Archeological excavation and find of impactites Reference: Buchner, E. et al. (2011) 74th Ann. Meteoritical Soc. Meeting, Abstract #5048. Schmieder, M. et al. (2011). 74th Ann. with glass below foundations of a Romanesque church. Meteoritical Soc. Meeting. Abstract #5059. Ernstson, K. et al. (2013) Meteoritics & Planet. Sci., 48, s1, Abstract #5058. Berger, N. (2014) Diploma thesis, University of Trier. Berger, N. et al. (2015) 46th LPSC, Abstract #1255.