松辽盆地白垩系泉三段—嫩二段沉积旋回与米兰科维奇周期

Sedimentary Cycles of the Cretaceous Quantou—Nenjiang Formations and Milankovitch Cycles of the South Hole of the SLCORE-Ⅰ in the Songliao Basin

松科1井南孔钻探是973项目“白垩纪地球表层系统重大地质事件与温室气候变化”的重要组成部分，是中国大陆第一口以白垩系地层为主的全取心科学探井。松科1井南孔取心段是从嫩二段底部一泉三段顶部，根据颜色、岩性岩相将此套地层划分成862个米级旋回。米级旋回可以识别出正粒序旋回、反粒序旋回和非粒序旋回3种类型，其中正粒序旋回包括6种亚类型，反粒序旋回包括7种亚类型，非粒序旋回包括3种亚类型。根据Fischer图解分析将米级旋回归并为更高级的2个级别旋回，分别是5级旋回和4级旋回。同位素年龄的旋回周期估算显示，米级旋回周期在22．9～29．8ka之间，5级旋回周期在75．0～104．7ka之间，4级旋回周期在225．0～460．0ka之间，分别与米兰科维奇岁差周期19-24ka、偏心率短周期85～140ka和偏心率长周期350-400ka存在着对应关系，说明松科1井南孔旋回地层的形成受米兰科维奇旋回的控制。松科1井沉积旋回的米兰科维奇周期的确定有助于揭示白垩纪的气候变化。

The south hole of the SLCORE is an important component of ＂Major Geological Events in the Earth Surface System during the Cretaceous and Greenhouse Climate Change＂ Project, sponsored by the National Basic Research Program （973 Program）. ＂SLCORE-Ⅰ＂ is the first scientific well focusing on the Cretaceous strata. The core rocks of the south hole of SLCORE-Ⅰ were taken from the top of the third member, Quantou Formation, Qingshankou Formation, Yaojia Formation, and the bottom of the second member, Nengjiang Formation. Based on the color, lithology and rock facies, the strata are divided into 863 meterscale cycles, which can be further divided into three types： normal grading, reverse grading and non grading cycles. The normal grading cycle includes six sub-types, the reverse grading cycle includes seven-sub types and the non grading cycle includes three sub-types. Based on the Fischer plots of this hole, meter-scale cycle, the sixth order cycle may form the fifth and fourth order cycles. The estimation of isotope age about the cycles of this hole shows that the meter-cycle period is between 22.9ka and 29.8ka, the fifth order cycle period is between 75.0ka and 104.7ka, and the fourth order cycle period is between 225.0ka and 460.0ka, corresponding with 19-24ka of the precession of equinox, 85-140ka of the short eccentricity, and 350-400ka of the long eccentricity of Milankovitch cycles respectively. It is suggested that the formation of cyclostratigraphy of the south hole of SLCORE-Ⅰ was controlled by the Milankovitch cycles, which is helpful to discover the climatic changes of Cretaceous in the Songliao basin.