Extreme zircon O isotopic compositions from 3.8 to 2.5Ga magmatic rocks from the Anshan area, North China Craton
Abstract Most zircon from Archean (3.8–2.5 Ga) trondhjemitic rocks, meta-gabbro, meta-diorite and monzogranite from the Anshan area, North China Craton, has δ18O values in the range of 4.6–7.5‰, but some has extreme compositions (0.02–11.0‰, with one value as low as − 11.3‰) as a result of pre-, syn- and post-magmatic processes. Nearly all zircon grains with very low δ18O (
A 13C nmr study of a diazo, of two diazonium salts and of some other model pyrazole compounds is reported. It is found that the C-4 diazo carbon is more shielded than the normal sp2 pyrazole hybridized carbon, while its diazonium salt is more deshielded. The electron density on the C-4 of the diazopyrazole is probably due to the positive charge on the terminal nitrogen. Thus the 13C chemical shift values allowed us to understand the chemical behaviour of a compound of potential antitumor activity.