An astronomical tuning strategy for Pliocene sections: implications for global-scale correlation and phase relationships
An astronomical tuning strategy for Pliocene sections: implications for global-scale correlation and phase relationships
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上新世剖面的天文调谐策略：对全球尺度相关性和相位关系的影响
DOI：
10.1098/rsta.1999.0409
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
S. Clemens
中科院分区：
文献类型：
--
作者：
S. Clemens
Astronomical tuning plays a central role in developing the chronostratigraphy of marine sediment sections. For Pleistocene sections, tuning is typically accomplished by matching the 41 and 23ka components of oxygen isotopes (δ18O−41, δ18O−23) to orbital obliquity and precession with constant phase lags of 69 degrees and 78 degrees, respectively (depleted (δ18O−41 lags maximum obliquity by 7.8ka, while depleted δ18O−23 lags minimum precession by 5ka). This approach places all records on the same time–scale relative to one another and relative to insolation forcing because Pleistocene δ18O is globally correlative. Thus, lead and lag relationships among climate variables measured at globally distributed sites can be assessed in an effort to understand the underlying physics of climate change. For Pleistocene sections, variables such as dust content, magnetic susceptibility, colour reflectance, and gamma–ray attenuation porosity evaluator (GRAPE) are typically tuned directly to precession or to a precession–dominated insolation target. Unlike Pleistocene δ18O, these variables are not globally correlative and few have unambiguous models linking them to insolation forcing. Consequently, the capacity to compare Pliocene lead and lag relationships among climate variables from different sites is considerably diminished, as is the capacity to evaluate the climate response to orbital forcing. Here a Pliocene tuning strategy is presented which builds on the precession–based approach by incorporating a final tuning step involving (δ18O−41. Results from application to Site 659 and the Mediterranean Rossello Composite Section suggest qualified success. Application to other Pliocene sections is required to verify the utility of this astronomical tuning approach.
