THE ASTRONOMICAL THEORY OF CLIMATE AND THE AGE OF THE BRUNHES-MATUYAMA MAGNETIC REVERSAL
THE ASTRONOMICAL THEORY OF CLIMATE AND THE AGE OF THE BRUNHES-MATUYAMA MAGNETIC REVERSAL
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DOI：
10.1016/0012-821x(94)90244-5
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发表时间：
1994-08-01
影响因子：
5.3
通讯作者：
LANCELOT, Y
中科院分区：
文献类型：
--
作者：
BASSINOT, FC;LABEYRIE, LD;LANCELOT, Y
在氧同位素第16阶段以下，沙克尔顿等人[1]从赤道太平洋ODP站点677开发的轨道导出的时间尺度与以前的有很大不同[例如，2-5]，得出最后一次地球磁翻转的估计年龄，比K/Ar值老5-7%[6-8]，但与最近的Ar/Ar测年法非常一致[9-11]。这些结果表明，在较低的Brunhes和上Matuyama年代带，迄今为止检索到的大多数深海气候记录显然错过或误解了天文气候理论预测的几个振荡。为了验证这一假设，我们研究了来自巨大活塞岩芯MD 900963（热带印度洋马尔代夫地区）的高分辨率氧同位素记录，其中由于局部盐度信号叠加在全球冰量信号上，因此deltaO-18中的岁差相关振荡特别好地表达[12]。与SPECMAP合成曲线[4，13]相比，在岩芯MD 900963的氧同位素阶段17和18中观察到三个额外的岁差相关周期，并且阶段21清楚地呈现出三个岁差振荡，如Shackleton等人[1]所预测的那样。在MD 900963岩芯δ O-18记录中发现的岁差峰值与天文气候理论预测的气候振荡非常一致。因此，我们的δ O-18记录允许发展一个精确的天文时标。根据我们的年龄模型，Brunhes-Matuyama反转的年龄为775 +/- 10 ka，与Shackleton等人[1]获得的780 ka的年龄估计和最近的熔岩放射年代学Ar/Ar年龄[9-11]非常一致。我们开发了一个新的低纬度，上更新世deltaO-18参考记录叠加和调整的deltaO-18记录从核心MD 900963和网站677轨道强迫功能。
Below oxygen isotope stage 16, the orbitally derived time-scale developed by Shackleton et al. [1] from ODP site 677 in the equatorial Pacific differs significantly from previous ones [e.g., 2-5], yielding estimated ages for the last Earth magnetic reversals that are 5-7% older than the K/Ar values [6-8] but are in good agreement with recent Ar/Ar dating [9-11]. These results suggest that in the lower Brunhes and upper Matuyama chronozones most deep-sea climatic records retrieved so far apparently missed or misinterpreted several oscillations predicted by the astronomical theory of climate. To test this hypothesis, we studied a high-resolution oxygen isotope record from giant piston core MD900963 (Maldives area, tropical Indian Ocean) in which precession-related oscillations in deltaO-18 are particularly well expressed, owing to the superimposition of a local salinity signal on the global ice volume signal [12]. Three additional precession-related cycles are observed in oxygen isotope stages 17 and 18 of core MD900963, compared to the SPECMAP composite curves [4,13], and stage 21 clearly presents three precession oscillations, as predicted by Shackleton et al. [1]. The precession peaks found in the deltaO-18 record from core MD900963 are in excellent agreement with climatic oscillations predicted by the astronomical theory of climate. Our deltaO-18 record therefore permits the development of an accurate astronomical time-scale. Based on our age model, the Brunhes-Matuyama reversal is dated at 775 +/- 10 ka, in good agreement with the age estimate of 780 ka obtained by Shackleton et al. [1] and recent radiochronological Ar/Ar datings on lavas [9-11]. We developed a new low-latitude, Upper Pleistocene deltaO-18 reference record by stacking and tuning the deltaO-18 records from core MD900963 and site 677 to orbital forcing functions.