Padvarninkai meteorite, Androniski, Anyksciu, Utena County, Lithuaniai

Regional Level Types
Padvarninkai meteorite	Meteorite Fall Location
Androniski	- not defined -
Anyksciu	Municipality
Utena County	County
Lithuania	Country

Eucrite, monomict, heavily shocked
Fall, 9 Feb 1929; 3.86 kg


Several months after the February fall eleven stones were recovered. The main mass, a 2.128 kg stone, still remains at Vilnius University. Compositionally, Padvarninkai is a fairly normal Eucrite rich in both pyroxene and plagioclase with the customary assortment of minor silicates, opaques, and other phases. The pyroxene is mostly orthopyroxene with exsolved augite while the plagioclase is mostly bytownite and anorthite. Lesser amounts of chromite, ilmenite, pigeonite, tridymite and troilite are reported by several authors. Small amounts of apatite and very small zircon grains (<25 µm) have provided opportunities to date Padvarninkai events utilizing multiple isotopic systems (K-Ar; Rb-Sr; Sm-Nd; Pb-Pb).

However, even if Padvarninkai is compositionally normal, its petrographic and mineralogical textures are quite extraordinary as it is unusually rich in glass, veins, and other shock-induced features. Extreme shock has melted and vitrified many portions of the stone. Three primary lithologies have been described: (1) Fine and coarse grained eucritic clasts, (2) a fine grained quenched, maskelynite-rich lithology, and (3) a partially glassy matrix surrounding various clasts of pyroxenes, feldspars and metal.

During the past two decades a number of studies have used different isotopic chronometers to date, provisionally in some instances, important events between the formation of Padvarninkai's mineralogical assemblages on its original parent body (presumably Vesta) and its eventual 1929 collision with the earth. Sm-Nd and Pb-Pb systematics give clear evidence of early lithification ~4.5 billion years ago. Ar39-Ar40 and Rb-Sr systematics provide evidence of energetic disturbances (impacts!?)~ 4.1, 3.8 and only 1.15 billion years ago. Refinements are sure to come, but progress appears to continue.

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References