正Objective The Jehol Biota,a world-famous Early Cretaceous fossil Lagerst?tte characterized by the traditional Eosestheria-Ephemeropsis-Lycoptera(EEL)assemblage,has a wide distribution over most parts of northern China,the coastal area of southeastern China,southeastern Mongolia,Transbaikalian area of Russia,Korea and Japan(Shao et al.,2017).The Baishan Basin,situated in 相似文献
The kinetics of metamorphism of the Staroe Boriskino C2 chondrite heated at 450°C in an inert atmosphere of helium flow was investigated. After being heated at 450°C during 160 minutes one specimen was moreover heated for 10 minutes at 500°C. The phase distribution was determined by means of Mössbauer spectroscopy, X-ray diffraction analysis, and electron probe microanalysis.The material changes rapidly (1–2 minutes). As a result of dehydration, the iron of the phyllosilicate is oxidized, the charge compensation being realized through the removal of iron and magnesium cations with the formation of magnetite and forsterite. Upon 10 minutes additional heating at 500°C iron appears in the olivine structure, the degree of iron oxidation declines, and magnetite disappears. Possible trends of change of C2 chondrite material are: