依-舒地堑北段第三系几组地层时代的讨论

THE DISCUSSION ON A FEW FORMATIONS’GEOLOGICAL AGE OF TERTIARY IN THE NORTH PART OF YI-SHU GRABEN

讨论范围为依-舒地堑的黑龙江省部分。丁山村组系这里下第三系的一个组名,后来被改积达连河组,时代被定为古新世～渐新世。道台桥组以砂砾岩为主,曾被放入中新统～上新统。大罗勒密玄武岩见于地堑的尚志-汤原段,时代一直被认为上新世。通过对尚志丁山村建组剖面孢粉化石的研究,证实它因缺少古老孢粉化石而新于古新统乌云组,又因缺少草本植物花粉而老于渐新统宝泉岭组,时代应为始新世。尚志费家街剖面曾被划入道台桥组,草本植物花粉在该组孢粉组合中占绝对优势,但该组合所含孢粉类型具明显的上第三系特征,时代应为上新世。K-Ar法同位素年龄资料证实尚志-汤原地区玄武岩形成年龄为30.3～12.0Ma,大罗勒密玄武岩的时代为渐新世～中新世。

The region discussed in this paper is the part of Yi-Shu graben in HeilongjiangProvince. Dingshanchun Formation is a Formation name of Eogene system here, and itis called Dalianhe Formation later. Its geological age is defined as Palaeocene-Oligocene.Daotaiqiao formation mainly consists of conglomerate and sandstone, and its geologicalage was considered as Miocene-Pliocene. Daluolemi basalt was found in Shangzhi-Tangyuan part of Yi-Shu graben, its geological age is considered as Pliocene all thetime. By studying sporopollen fossils in the section of Shangzhi and Dingshanchun forma-tion, this paper proved that it lacks ancient sporopollen fossils, its geological age isnewer than that of Wuyun formation of Palaeocene and should be Eocene. Shangzhi Fei-jiajie section was considered as Daotaiqiao formation, its herb pollen owns absolute su-periority in sporopollen assemblage, its pollen type obviously has the feature of Neo-gene, its age should be Pliocene. The geological age of basalt in Shangzhi-Tangyuan re-gion is 30. 3～12. 0Ma by K-Ar isotope geological age information. The geological age ofDaluolemi basalt is Oligocene-Miocene.