23亿年地质环境突变的证据及若干问题的讨论

<正> 国际前寒武地层分会投票表决25亿年为太古宙与元古宙的分界,有学者坚持以23亿年作为太古宙与元古宙的分界,表明23亿年是地球演化史上的重要时间。然而,23亿年左右的地质事件并没有受到足够的重视。在对华北克拉通南缘结晶基底的研究中,陈衍景注意到岩石圈表层、大气圈、水圈、生物圈等的性质在23亿年左右发生了根本性变化。初步推测此变化与地外因素有关。

Evidences for the catastrophe in geologic environment at about 2300 Ma and the discussions on several problems

The catastrophe in geologic environment occurred at about 2300 Ma is supported by the following facts which happened on every continent from 230C Ma onwards: carbonate and phosphate started to deposit in a large quantity, a great amount of stromatolite appeared suddenly, banded iron formations were most intensively developed, red beds came into being universally, glacial event occurred, sediments began to deplete in Eu, and so on.After the catastrophe, the atmosphere abundant with 02 formed drastically and microorganism flourished and evolved rapidly.The catastrophe was probably resulted from an extraterrestrial event and can be regarded as the Archean-Proterozoic boundary.