东北依兰—伊通地堑方正断陷方正组的建立及其意义

THE FANGZHENG FORMATION OF THE FANGZHENG RIFT IN THE NORTHEAST OF THE YILAN-YITONG RIFT VALLEY AND ITS SIGNIFICANCE

依兰—伊通地堑方正断陷方参 2井 2 10 4.0— 3 45 0 .0 m井段为一套红色碎屑岩 ,产有孢粉化石 Cicatrico-sisporites,Lygodiumsporites,Appendicisporites,Concavissimisporites,Gleicheniidites,Cyathidites,Cibotiumspora,Foraminisporis,Taxodiaceaepollenites,Inaperturopollenites,Triporopollenites和 Tricolporopollenites等。依据岩性及孢粉资料 ,在方正断陷建立方正组 ,并认为方正组时代为晚白垩世早期——赛诺曼期。通过与邻区松辽盆地泉头组、阜新盆地孙家湾组、延吉盆地龙井组等对比 ,认为东北地区这一套红层沉积具有广泛分布的特点 ,它是干热气候事件的产物。

Sporopollen fossils Cicatricosisporites, Lygodiumsporites, Appendicisporites, Concavissimispo-rites, Gleicheniidites, Cyathidites, Cibotiumspora, Foraminisporis, Taxodiaceaepollenites, Inaperturopollenites, Triporopollenites, Tricolporopollenites etc. were obtained from the red clastic rocks of the Fangcen borehole 2 from 2104.0 metre to 3450.0 metre in the Fangzheng Rift, northeast of the Yilan-Yitong Rift Valley. Based on the lithologic feature and sporopollen fossil assemblage, the holostratotype of the Fangzheng Formation is established in the Fangzheng Rift. The authors consider its geological age to be early Late Cretaceous——Cenomanian. Through correlation with the Quantou Formation of the Songliao Basin, Sunjiawan Formation of the Fuxin Basin, Longjing Formation of the Yanji Basin, the conclusion is acquired that the red clastic rocks is widespread in NE China, and it is the result of the climate event of dryness and torridity.