“第四纪”一词之存废及其下界之浅见

与第四纪同时产生的第一纪、第二纪和第三纪等名词已先后被废弃,第四纪一词已失去其意义,建议予以废弃。第四纪是人类生活的时代,故建议用“人类纪”称之。第四纪的下界建议采用古地磁年表上的松山/高斯(M/G)界线,即258万年。其理由是:1)地磁极的大转换本身就是一个事件,它可能与其他事件有着因果的关系;2)在此线附近发现微玻璃陨石和铱微粒与铱异常,代表天文撞击事件;3)火山喷发物的发现是火山活动的证据;4)植物界在此线上下有巨大变化,在此线以下出现许多热带-亚热带植物,此线以上为温带植物;5)动物界也有巨大变化,三趾马动物群为现代动物群和人类所代替,最早的人属化石年龄为240万年;6)南海地区有Globorotaliamultcamerata绝灭事件,北京海进层中有波罗的透明虫等冷水种有孔虫组合出现;7)黄土高原的三趾马红土变成黄土。可见,M/G界线是一条很显著的界线,足以作为人类纪的下界。

“QUATERNARY&rdquo|SHOULD BE RESERVED OR DISCARD, AND WHERE IS ITS LOWER BOUNDARY?

The terms “Primary”, “Secondary”, and “Tertiary” have recently been discarded.So, as a consequence, “Quaternary” has lost its meaning thus should be discarded. Quaternary is the time of human being. So, it is better for us to replace “Quaternary” with “Anthropogene”. The Matuyama/Gauss boundry (2.58Ma) is the best place for the lower boundary of the Anthropogene. Near this place, a lot of geological events took place: (1)Alternation of geomagnetic polarity, itself is an major event; (2) Micro-glass-aerolite and Iridium abnomal means a cosmical stricke event; (3) Discovery of volcanic ash and volcanic micro grains indicated a volcanic event; (4)Subtropic plants replaced by the plants of temperate zone; (5)Older animals of Neocene Hipparion fauna replaced by present fauna; (6)Extinct of Australopithecus and flourishing of human being; (7)Red clay changed into loess. So, the lower boundry of Anthropogene is very clear.