地层记录的灾害性撞击事件

在目前已知的约160个撞击坑结构中,有30％为沉积层,目前尚未发现的撞击坑结构仍藏匿在沉积层里,特别是藏匿在海底。即使这些撞击坑结构被表面更新的地质过程所湮灭,撞击抛射物和小天体残骸仍然会残留在沉积层里,显示出与撞击有关的地球化学异常和地球物理异常,从而为小天体撞击事件提供了实地调查的证据。虽然目前只发现了为数很少的证据,但是在地层记录里发现撞击证据已经形成小天体撞击研究的一个重要领域。本文对这个领域的研究成果作了一个简要的评述。

THE DEVASTATING IMPACT EVENTS IN THE STRATIGRAPHIC RECORD

Thirty percent of 160 are known impact crater structures are buried by postimpact sediment, and there must be much more impact crater structures that have not be found in the sediment, especially in the oceanic bottom. Even if the impact craer structures were destroyed by it active geologic processes causing surface renewal, the impact ejecta and dedris of NEOs had survived and marked the geohysical and geopchemical anomalies related to impact in the sediment, providing NEO impact events with new ground evideces. Though a limited number of stratigraphic evidences discovered, the discovery of the evidences for impacts in the strati-graphic record has developed an important research area of NEO impacts. This paper will present a brief review of studies head in this direction.