Chronological framework for Lake Baikal and Lake Elgygytgyn drill cores and orbital forcing of continental climate in the Northern Hemisphere during the past 3.6 Ma

我们建议利用icdp资助的钻探项目获得的两个世界上最长的连续古气候记录：西伯利亚东北部Elgygytgyn湖最近获得的3.6 ma记录和西伯利亚东南部贝加尔湖记录的最上层3.6 ma记录，对上新世-更新世期间北半球大陆气候的(a)轨道强迫和(b)演化进行新的理解。我们将为这两个记录开发一个共同的轨道调谐时间尺度，建立两个记录中单个冰期-间冰期间隔的精确相关性，并详细说明它们与海洋氧同位素阶段的关系。然后，我们将使用由此产生的新的共同时间标度来解决(i)上新世“41-kyr世界”的大陆代用记录中的轨道特征，（ii）北半球冰川开始于2.7 Ma，以及（iii）向“100-kyr世界”的过渡。我们将进一步解决（iv） 41-kyr世界海洋δ18O记录中缺少进动频率方差的“谜团”，以及(v)验证高纬度轨道强迫大陆信号是否与上新世冰期起源的“纬向热梯度假说”相一致。对过去3.6 Ma的贝加尔湖-埃勒吉格金的系统比较也将在轨道时间尺度上阐明(6)北极与北半球中纬度高纬度地区相比气候变化放大的机制。

We propose to develop a new understanding of (a) orbital forcing and (b) evolution of the Northern Hemisphere continental climate during the Plio-Pleistocene using two world’s longest continuous paleoclimate records obtained in ICDP-funded drilling projects: the recently obtained 3.6-Ma record from Lake Elgygytgyn, NE Siberia, and the uppermost 3.6-Ma portion of the record from Lake Baikal, SE Siberia. We will develop a common orbitally-tuned timescale for both records, establish accurate correlations of individual glacial-interglacial intervals in both records, and detail their relationship to marine oxygen isotope stages. We will then use the resultant new common timescale to address the orbital signatures in the continental proxy records of (i) the Pliocene ’41-kyr world’, (ii) the inception of the Northern Hemisphere glaciations at 2.7 Ma, and (iii) the transition to the ‘100-kyr world’. We will further address (iv) the ‘mystery’ of missing variance at precession frequencies in the marine δ18O records of the 41-kyr world, and (v) test if the high-latitude orbitally-forced continental signal is consistent with the ‘latitudinal heat gradient hypothesis’ on the origin of the Pliocene ice-ages. A systematic Baikal-Elgygytgyn comparison over the past 3.6 Ma will also shed light on (vi) the mechanisms of amplification of climate changes in the Arctic as compared to those in the upper mid-latitudes of the Northern Hemisphere on orbital time scales.