从介形类化石谈松辽盆地嫩江组的地质时代

ON THE AGE OF NENJIANG FORMATION IN SONGLIAO BASIN BASED ON OSTRACODA

张小筠 宗建华

Zhang Xiaoyun Zhong Jianhua

松辽盆地白垩系嫩江组中除含丰富的介形类化石外,还含有丰富的叶肢介、瓣鳃类、腹足类、植物、轮藻、孢粉以及爬行动物、鱼化石等。因此,以某一门类化石为根据曾对其地质时代作过详细论述(表1)。多数研究者主张将该组归于晚白垩世,少数主张归于早白垩世,而介形类工作者,多数主张归于早白垩世。我们认为嫩江组的地质时代划为晚白垩世早期为宜,其理由为(表2):(1)含有一定数量的晚白垩世标志化石 Talicypridea=Cristocypridea。

It is appropriate to ascribing the Nenjiang Formation in Songliao Basin to the early Late Cretaceous time.The main evidence is that the Nenjiang Forma-tion contains ,the typical fossil of the Late Cretaceous,which often coexisted with Dinosaur eggs typical also of the Late Cretaceous.Further-more,the ()and the Cypridea cavernosa are quite com-mon in this formation.Apart from that,it contains some Cenozoic compo-nent such as Candona,Condoniella and Eucypris.The feature of Ostracoda are quite similar to those in the overlying Upper Cretaceous Sifanstai and Ming-shui Formations.

10.11743/ogg19840110