NaAlSi3O8-hollandite and other high-pressure minerals in the shock melt veins of the Suizhou meteorite

The Suizhou L6 chondrite contains a few very thin shock melt veins of 0.02- 0.09 mm in width. In spite of small width of the veins, shock-induced high- pressure phases, such as coarse-grained NaAlSi3O8-hollandite, ringwoodite, majorite and fine-grained matrix majorite-pyropess. have been discovered in these veins. NaAlSi3O8-hollandite, the high-pressure phase of plagioclase, in Suizhou shock veins occurs as a single phase mineral, no silicate glass y phase, such as albitic glass, was incorporated with it. The presence of a bove-mentioned high-pressure phases constrains the high pressure (up to 23- 24 GPa) and high temperature (up to 1900-2000 degreesC) regime in Suizhou s hock veins, and indicates that the duration of high-pressure regime in the veins should be long enough (a few seconds) for phase transformation and cr ystallization of minerals under pressure. The discovery of the first natura l single-phase crystalline NaAlSi3O8- hollandite in Suizhou meteorite Is of important significance in understanding the Earth's mantle geochemistry.