Physics
Scientific paper
Dec 2002
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2002agufmmr61a1033x&link_type=abstract
American Geophysical Union, Fall Meeting 2002, abstract #MR61A-1033
Physics
1025 Composition Of The Mantle, 1212 Earth'S Interior: Composition And State (8105), 3662 Meteorites, 3924 High-Pressure Behavior, 3944 Shock Wave Experiments
Scientific paper
High-pressure minerals are common in highly shocked (S6) L6 chondrites, occurring within or adjacent to shock-induced melt veins and melt pockets. They provide natural examples of high-pressure minerals that make up the Earth's transition zone (410 to 660 km depth) and lower mantle, as well as a record of high-pressure and temperature conditions during impact events on chondrite parent bodies. The high-pressure minerals that crystallize in melt veins and pockets can be used as an alternative means of investigating shock pressure. We used transmission electron microscopy (TEM) to characterize the shock-vein mineralogy in seven L6 chondrites ranging from shock stage S6 to S3: Tenham (S6), Umbarger (S6), Roy (S3-5), Ramsdorf (S4), Kunashak (S4), Nakhon Pathon (S4) and La Lande (S4). Tenham contains assemblages that reflect variable cooling rates during crystallization. Majorite plus magnesiow\x81stite occur in the center of melt veins, whereas ringwoodite, akimotoite and round amorphous grains (probably vitrified MgSiO3-pervoskite) occur along melt-vein edges. In addition, a symplectitic intergrowth of majorite and an amorphous phase has been observed, which probably represents clinopyroxene that has disassociated into majorite plus CaSiO3-pervoskite. High pressure minerals in the Umbarger melt veins include: ringwoodite, akimotoite ((Mg,Fe)SiO3-ilmenite), augite, and hollandite-structured plagioclase. In addition, Fe2SiO4-spinel (new mineral) and stishovite occur in SiO2-FeO rich melt. High-pressure minerals in the Roy melt veins include ringwoodite and majorite. Melt veins in Ramsdorf, Kunashak, Nakhon Pathon and La lande contain fine-grained olivines and pyroxenes that are defect free and interpreted as having crystallized from the melt. Crystallization pressures can be inferred from the mineral assemblages in the melt veins and available phase equilibrium data. Melt veins in Tenham crystallized at pressure of approximately 25 GPa; Umbarger at pressure between 18 to 25 GPa; Roy at pressure between 14 to 22 GPa; Ramsdort, Kunashak, Nakhon Pathon and La lande at pressure up to to15 GPa.
Sharp Thomas G.
Xie Zhaohua
No associations
LandOfFree
Estimating Shock Pressures in Chondrites From High-Pressure Minerals in Shock-induced Melt Veins does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Estimating Shock Pressures in Chondrites From High-Pressure Minerals in Shock-induced Melt Veins, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Estimating Shock Pressures in Chondrites From High-Pressure Minerals in Shock-induced Melt Veins will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1892526