琼东南盆地莺歌海组—黄流组海平面变化与层序年代地层

Sea Level Change and Sequence Chronostratigraphy of the Yinggehai-Huangliu Formation in the Qiongdongnan Basin

琼东南盆地晚第三纪莺歌海组—黄流组为巨厚海相沉积,此时期内发生过多次海平面升降。本文依据对崖A-2井有孔虫化石丰度和分异度的定量分析、崖A-1井表层浮游有孔虫壳体氧、碳稳定同位素分析、地震剖面中上超点迁移分析及对盆地古水深的恢复来研究相对海平面变化。对琼东南盆地主干地震剖面进行了层序划分,在莺歌海组—黄流组识别出9个层序。据最新修订的地磁极性时间表、天文时间表和新生代地质年代表建立了莺歌海组—黄流组层序年代地层格架,重新厘定9个层序的界面年龄值。

The Neogene Yinggehai-Huangliu Formation in the Qiongdongnan basin consists of very thick marine deposits. Many cycles of sea-level changes have occurred in this epoch. The sea-level changes were related to sequences and bioevents. Based on quantitative studies of the abundance and diversity of foraminifers from the Ya-A-2 well and oxygen and carbon isotopic records of planktonic foraminiferal tests from the Ya-A-1 well, the relative sea level change curve has been constructed in the Yinggehai-Huanglui Formation. In addition, the paper analyzes the migration of the onlap point in main seismic data and reconstructs the paleodepth of the sea water according to the slope-basin depositional system in the Qiongdongnan basin. Nine sequences have been recognized based on seismic data. Sequence chronostratigraphy has been established in the light of newly-revised geomagnetic polarity time scale for the Cenozoic, new late Neogene time scale and Cenozoic geologic time scale. The ages of nine depositional sequence boundaries have been determined again.