摘要
本文结合生物地层，同位素年代学，古地磁及地层序列的最新研究成果，探讨了松辽盆地断陷期营城组的时代归属。营城组孢粉组合多繁盛于白垩纪早中期的Hauterivian期－Albian期；营城组同位素年龄分布表现出两个峰值135～120Ma和115～110Ma，结合采样层位及地层序列特征认为135～130Ma代表营城组下段中基性火山岩的年龄，130～120Ma代表营城组一段酸性火山岩的年龄，115～110Ma代表营城组三段基性火山岩及顶部酸性火山岩的年龄；古地磁研究表明在Hauterivian期底界偏上的135Ma发生过磁性的倒转以及松辽盆地的快速北移。这些特征表明营城组的时代为Hauterivian期～Albian早期，同位素年龄为135～110Ma。
The chronostratigraphy of the Lower Cretaceous Yingcheng Formation （K1y） of the Songliao Basin was disscussed and summarized on the basis of biostratigraphy, isotopic dating,lithostratigraphy as well as magnetostratigraphy. The Yingcheng Formation is composed of five members which from bottom to top are the lowest member dominated by intermediate--basic volcanic rocks, member-1 of acidic volcanic rocks, member-2 of volcaniclastic sediments, member-3 characterizeed by interbeded basaltic--acidic volcanic rocks and member-4 consists mostly of conglomerate, respectively. The sporo-pollen assemblages of the K1y showed a blooming age from Hauterivian to Albian of early Cretaceous. The isotopic ages dated on the volcanic rocks/tuffs of the K1y showed two peaks in the histogram ranging from 135 Ma to 120Ma and from 115Ma to 110Ma, respectively. The dating range of the 135-130 Ma is from the lowest member of the formation, the 130-120Ma from member-1, and the last peak of the 115 - 110Ma from member-3 of the K1y, respectively. The magnetostratigraphy of the Songliao Basin showed a magnetic inversion above the bottom of Hautervian stage, meanwhile the paleolatitude migration curve shows the basin＇s fast moving towards north at the age of 135Ma. All these evidences suggest that the age of the Yingcheng Formation can be well constrained from Hauterivian to early Albian with a chronology age ranging from 135Ma to 110Ma.
出处
《地质论评》
CAS
CSCD
北大核心
2008年第4期439-448,共10页
Geological Review
基金
国家重点基础研究发展规划(973)项目(编号2006CB701403)的成果
关键词
营城组
白垩纪
地层年代
松辽盆地
Yingcheng Formation
Chronostratigraphy
Volcanogenic succession
Cretaceous
Songliao Basin
