V. F. Velázquez, C. Riccomini, J. M. Azevedo Sobrinho, A. S. Rankin, A. M. E. Sallun, J. Hachiro and L. G. Sant’ Anna, “Microscopic Evidence of Shock Metamorphism Effects in Detrital Minerals from the Col?nia Crater Sediments, SP,” 45th Congresso Brasileiro de Geologia, Belem, 2010.

has been cited by the following article:

• TITLE: Evidence of Shock Metamorphism Effects in Allochthonous Breccia Deposits from the Colônia Crater, São Paulo, Brazil

  AUTHORS: Victor F. Velázquez, Claudio Riccomini, José M. Azevedo Sobrinho, Mikhaela A. J. S. Pletsch, Alethéa E. Martins Sallun, William Sallun Filho, Jorge Hachiro

  KEYWORDS: Colônia Crater; Polymictic Allochthonous Breccia; Shock Metamorphism Effects

  JOURNAL NAME: International Journal of Geosciences, Vol.4 No.1A, January 29, 2013

  ABSTRACT: The 3.6 km-diameter Colonia impact crater, centred at 2352'03"S and 4642'27"W,lies 40 km to the south-west of the S?o Paulo city. The structure was formed on the crystalline basement rocks and displays a bowl-shaped with steeper slope near the top that decreases gently toward the centre of the crater. Over recent years were drilled two boreholes inside the crater, which reached a maximum depth of 142 m and 197 m. Geological profile suggests four different lithological associations: 1) unshocked crystalline basement rocks (197 - 140 m); 2) fractured/brecciated basement rocks (140 - 110 m); 3) polymictic allochthonous breccia deposits (110 - 40 m); and 4) post-impact deposits (40 - 0 m). Petrographic characterisation of the polymictic allochthonous breccia reveals a series of distinctive shock-metamorphic features, including, among others, planar deformation features in quartz, feldspar and mica, ballen silica, granular texture in zircon and melt-bearing impact rocks. The occurrence of melt particles and very high-pressure phase transformation in suevite breccia suggest a shock pressure regime higher than 60 GPa.