学术报告

应环境磁学实验室邀请，加拿大阿尔伯塔大学物理系（Physics Department University of Alberta）Vadim A. Kravchinsky教授来我所作学术报告，欢迎各位老师、同学光临。

报告题目：The long-term astronomical periodicities in the Lake Baikal deep drilling sediments

报告人：Prof. V.A. Kravchinsky

Physics Dept., University of Alberta, Edmonton, AB, T6G 2G7, Canada

时间：2010年5月21日（星期五）15:00

地点：地环所二楼学术报告厅

The long-term astronomical periodicities in the Lake Baikal deep drilling sediments

V.A. Kravchinsky¹

¹ Physics Dept., University of Alberta, Edmonton, AB, T6G 2G7, Canada

Phone: 780-4925591; Fax: 780-4920714; Email: vkrav@phys.ualberta.ca

Records of climatic change, such as lacustrine and eolian sediments agree well with the marine records for the last couple million years. Continuous terrestrial records for longer time intervals were unavailable until last decade when deep drilling Lake Baikal cores were recovered. Lake Baikal’s middle-high latitude position within the Asian interior ensures highest sensitivity of the climate to the Earth orbital parameter variations. Our earlier publications examined Milankovitch cyclicity in a number of the lake cores with ages spanning from the present day to 6.7 Ma. It was possible to demonstrate the high signal power in the narrow obliquity band confirming the strong orbital forcing on the climate. However, a 100 kyr period found in these records did not align with the orbital eccentricity in a way predicted by theory. Available Be¹⁰ chronology enabled me to adjust the magnetostratigraphy age model for certain time intervals and to revise the magnetic susceptibility and biogenic silica datasets. I compare my datasets with the theoretical insolation and oceanic oxygen isotope records and discuss the findings of the precession, obliquity, and eccentricity cycles as well as “non-Milankovitch” cycles of ~29 kyr and ~70 kyr. A notable absence of considerable eccentricity amplitude at 400 kyr in the oceanic records during the last few million years is well known in spite of this being one of the largest components of eccentricity forcing. At the same time, reported earlier 400 kyr and larger periodicities for the Lake Baikal sedimentary records were derived from the erroneous age model. I reexamine the long-term periodicities (400 kyr and longer) which are confidently represented in the Lake Baikal records.