摘要
Diamonds from eclogite in main hole of the Chinese Continental Scientific Drilling Project ( CCSD-MH) on the Sulu ultrahigh-pressure metamorphic ( UHPM) belt were formed by the deep subduction of continent crust,while diamonds from the Luobusa ophiolitic chromitites in the Yarlung Zangbo suture of Tibet were originated from the deep mantle. Thus,their formational background and mechanism are much different. A primary analysis of FT-IR show that UHPM diamonds are Ⅰ aAB type,and the ophiolitic diamonds areⅠaA type,both are different in the way of gather and evolvement for N-impurity. The FT-IRdata show that the diamonds from the two locations are natural diamonds,and the UHPM diamonds might formed earlier than the ophiolitic diamonds.