Terrestrial ages of ordinary chondrites from the Lewis Cliff stranding area, East Antarctica

摘要: Abstract— We determined terrestrial ages of ordinary chondrites from the Lewis Cliff stranding area, East Antarctica, on basis concentrations cosmogenic 10Be (t½; = 1.51 Ma), 26Al 0.705 and 36Cl 0.301 Ma). After an initial γ-ray survey 91 meteorites suggested that many have >0.1 Ma, we selected 62 for measurements by accelerator mass spectrometry (AMS) measured in twelve those. Low ( 2 Ma (Welten et al., 1997). Our major conclusions are: (1) The H-chondrites show similar to those Allan Hills icefields, but L-chondrites are about a factor younger than Hills, which indicates is area. (2) age distributions at different parts area generally agree with simple meteorite concentration models, although differences weathering rate may also play role. (3) confirm natural thermoluminescence (TL) levels >80 krad associated low (Benoit 1992) conclude TL <80 can not be used calculate meteorite. Natural do seem useful estimate relative large groups determine surface exposure paired fragments. (4) Of AMS, 31 were assigned 11 pairing groups, mainly their nuclide record. estimated represent between 42 52 distinct falls.