A 3.3-Ma Impact in Argentina and Possible Consequences
P. H. Schultz,
*
M. Zarate,
W. Hames,
C. Camilión,
J. King
Enigmatic glassy materials (escorias) and red bricklike
materials (tierras cocidas) occur at a restricted stratigraphic level (the top of the Chapadmalal Formation). Materials from one locality near Mar del Plata are attributed to a mid-Pliocene impact event with a
radiometric and magnetostratigraphic age of 3.3 million years ago (Ma).
An extinction of endemic fauna (including the glyptodonts and
flightless cariamid birds) correlates with the unit containing the
impact glasses. Moreover, the age of the glasses is coincident within
dating uncertainties with a pulselike change in the oxygen isotope
marine record in the Atlantic and Pacific Oceans just before the late
Pliocene deterioration of the climate.
P. H. Schultz, Geological Sciences, Brown University,
Providence, RI 02912-1846, USA. M. Zarate, Consejo Nacional de
Investigaciones Científicas y Técnicas, Instituto
Argentino de Nivologia y Glaciología, Centro Regional de
Investigaciones Científicas y Técnicas, cc 330, 5500 Mendoza, Argentina. W. Hames, Department of Geology, 210 Petrie Hall,
Auburn University, Auburn, AL 36849, USA. C. Camilión,
Consejo Nacional de Investigaciones Científicas y
Técnicas, Universidad Nacional de la Plata, 3#584, 1900 La Plata,
Argentina. J. King, Graduate School of Oceanography, Narragansett Bay
Campus, University of Rhode Island, Narragansett, RI 02882-1197, USA.
*
To whom correspondence should be addressed. E-mail:
Peter_Schultz{at}brown.edu.
