| PDF: | |
| Time: | 2008 |
| Journal: | Geological Review |
| Volumn: | 54 |
| Issue: | 4 |
| Pages: | 439-448 |
| Type: | Other |
| Author: | Juntao Jia,Pujun Wang,Xiaoqiao Wan |
Abstract: | 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 basins 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. |