GLASS SPHERES IN QUATERNARY DEPOSITS OF THE PAMPEAN REGION, BUENOS AIRES PROVINCE, ARGENTINA.

Authors

  • Adriana Mónica Blasi
  • Nauris V Dangavs

Keywords:

Glass spheres, Quaternary sediments, Meteoritic impact-derived glass, Bone combustion structures,

Abstract

The unusual occurrence of glass spheres in Quaternary deposits of Luján and San Vicente localities motivated this contribution to clarify their nature, origin and presence in fluvial sediments. The spheres are constituted by amorphous calcium silicate, with low aluminum participation, green yellowish to dark brown in colour. The glass is generally spherical, although ellipsoidal or elongate, tear-drop, bar-bell forms are also presento They are massive and with scarce external vesiculation, Three hypothesis about their possible origen are rised. One of them is related to volcanic genesis and the other to non-volcanic high temperature melting of different calcium rich materials. Morphological and compositional characteristics of the spheres rule out the former possibility. Conversely the observable features are very similar to glass spheres produced by fusion of marl sediments due to meteor impact or by melting of silicoclastic sediments in bone combustion structures.

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