84th Annual Meeting of The Meteoritical Society 2021 (LPI Contrib. No. 2609) 6240.pdf FIRST DISCOVERY OF PROXIMAL VREDEFORT IMPACT EJECTA IN SOUTH AFRICA M. S. Huber1, E. Kovaleva1, F. Mautle1, J. Hainsworth2, and C. Koeberl3 1Department of Earth Sciences, University of the Western Cape, Robert Sobukwe Road, 7535 Bellville, South Afri- ca; ([email protected]) 2Shango Solutions, Geological Consultancy, 22 Ethel Ave, Northcliff, Johannesburg, South Africa 3Department of Lithospheric Research, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria ([email protected]) Introduction: The ca. 2020 Ma [1] Vredefort impact structure in South Africa, one of the largest and oldest known on Earth, has been deeply eroded since its formation, with up to 10 km of exhumation taking place [2,3]. Due to the erosion, it has long been thought that all of the proximal ejecta around the Vredefort structure was completely removed. The only preserved impact ejecta probably derived from the Vredefort event have been found in Green- land [4] and Russia [5]. Possible Vredefort Ejecta: However, the Maremane Dome in South Africa, which is centered approximately 500 km to the west of the center of the Vredefort Dome, preserves sediments that are coeval with the Vredefort event [6]. The Maremane Dome is being actively mined for iron and manganese deposits at the Sishen, Khumani, Beeshoek and Kolomela iron ore mines. Currently, the exploration camps around the Maremane Dome and neigh- boring Aucumpsrust Dome are drilling new sites. At both the Khumani Mine and at an exploration camp near Postmasburg, anomalous breccias were identified in drill core, with 2 m of core from Khumani and 20 m of core from the exploration camp taken for further study. The breccias are constrained stratigraphically by the Hartley Bas- alt Formation (1928±4; [7]) and lavas of the Ongeluk Formation (2222±13 Ma; [8]), which includes the Vredefort age, but not other known impact craters, such as the nearby Jurassic age Morokweng structure [9]. The sections of core have been subjected to hydrothermal alteration, and both sections have chlorite and hematite mineralization overprinting the primary minerals, although there is little structural deformation. In both sections, accretionary lapilli were identified with diameters up to 4 cm that have well-developed rims containing fine-grained particles and cores containing larger grains. Inclusions within the breccia resemble altered fragments of glass that preserve flow textures. Individual grains of quartz preserve decorated planar deformation features with at most three sets in single grains. Zircon grains in both drill cores appear to contain multiple sets of planar microstructures. Preliminary chemi- cal analyses indicate that the Ni, Co, Cr, and Ir abundances are not particularly high, which may be due to the hydro- thermal overprinting the samples have experienced. Future studies will examine the shocked minerals in detail, in- cluding via electron backscatter diffraction, and resolve the geochemistry of the deposits. We suggest that these samples represent the first discovery of proximal ejecta related to the Vredefort impact event. References: [1] Moser, D. E. (1997) Geology 25:7-10. [2] Schreyer W. (1983) Journal of Petrology 24:26-47. [3] Gibson R. L. et al. (1997) Geochimica et Cosmochimica Acta 61:1531-1540. [4] Chadwick B. et al. (2001) Jour- nal of the Geological Society 158:331-340. [5] Huber M. S. et al. (2014) Geology 42:375-378. [6] Smith A. and Beukes N. (2016) Episodes 39:269-284. [7] Cornell D. H. et al. (1998) Journal of African Earth Sciences 26:5-27. [8] Cornell D. H. et al. (1996) Precambrian Research 79:101-123. [9] Koeberl C. et al. (1997) Geology 25:731-734. .