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长江三角洲地区的磁性地层认识存在很大不确定性.为建立一个可靠的年代标尺,为区内沉积环境和气候演化研究提供约束,在年代地层和磁性地层基础上,以频率磁化率为信号源、ETP为靶曲线,通过轨道调谐方法对区内LZK1孔开展了天文年代标尺研究,建立了年代序列框架.结果显示,M/B界线埋深约为143.0m、Ga/M界线埋深约为219.0m、Gi/Ga界线埋深约为296.6m.受气候和沉积环境控制,沉积旋回特征清楚,沉积速率具有明显的阶段性.调谐后的频率磁化率显示了显著的125ka、96ka、41ka、23ka、22ka、18ka等轨道周期,并在轨道周期上与ETP曲线高度相关,相关性超过了95%检验标准.100ka、41ka和23ka周期的带通滤波曲线与偏心率、斜率和岁差在振幅和相位上吻合较好,但局部时间段有差异,可能与低沉积速率、沉积速率突变或短时间尺度的地层缺失等因素有关.研究表明,在具有短暂沉积缺失的持续沉降区域,只要保证样品分辨率,可以通过轨道调谐方法建立可靠的年代框架.
There is great uncertainty in understanding the magnetic stratum in the Yangtze River Delta region.In order to establish a reliable date scale and provide constraints for the study of sedimentary environment and climate evolution in the area, based on the age stratigraphy and magnetic stratum, taking frequency magnetic susceptibility as signal source , ETP as the target curve, the chronological framework of the LZK1 hole in the area was developed by orbital tuning method, and the chronological framework was established.The results show that the M / B boundary depth is about 143.0m and the Ga / M boundary depth is about 219.0m, and the Gi / Ga boundary line buried depth is about 296.6m.Regarding the characteristics of sedimentary cycles and clear depositional cycles, the frequency-dependent magnetic susceptibility shows a significant increase after 125 ka, 96 ka, 41 ka, 23ka, 22ka, 18ka and other orbital periods, and highly correlated with the ETP curve over the orbital period, the correlation exceeded 95% of the test criteria. Bandpass filtering curves and eccentricity, slope and precession in 100ka, 41ka and 23ka cycles But the difference in local time period may be related to the factors such as low sedimentation rate, abrupt change of sedimentation rate or lack of stratum on short time scale.The research shows that in the area with short sediment loss Continuous settling area, as long as the sample resolution is guaranteed, the orbital tuning method can be used to establish a reliable chronological framework.