前乐平世海洋动物灾变事件在硅质岩系中的响应

Response of the Pre-Lopingian Marine Animal Crisis Event in Chert Sequence

在广西钦州地区小董镇大虫岭层状硅质岩剖面中,发现在乐平统底界附近,稀土元素地球化学Ce/ Ce*值的高异常带、稀土元素分布模式中Ce正异常层段(背景为负异常)以及岩性特征的明显变化段,与放射虫动物群的突然变化层位相吻合。这一研究结果说明,前乐平世海洋动物灾变事件在本剖面中有很好的响应。这一事件发生的原因是由于瓜德鲁普世末期全球性海退引起的,事件持续的时间较长,相当于卡匹敦期的晚期。

In a bedded chert section at Dachongling in Xiaodong town of Qingzhou, Guangxi, the authors found a rare earth elements （REE） geochemical anomaly zone with higher Ce/Ce＂ values, a positive Ce anomaly zone （the background is negative Ce anomalous zone） in the shale-normalized REE pattern, and a zone of sharp lithological change at the basal boundary of the Lopingian Series. These zones coincide with the zone of sharp change in radiolarian groups. This fact may indicate that the pre-Lopingian crisis event are reflected very well in this section. It is inferred that the cause of the event was a global regression at the end of the Guadalupian, and the event continued for a long time that is equal to the late Capitanian period.