期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2014
卷号：111
期号：32
页码：11630-11635
DOI：10.1073/pnas.1401547111
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Recent debate on records of southern midlatitude glaciation has focused on reconstructing glacier dynamics during the last glacial termination, with different results supporting both in-phase and out-of-phase correlations with Northern Hemisphere glacial signals. A continuing major weakness in this debate is the lack of robust data, particularly from the early and maximum phase of southern midlatitude glaciation ([~]30-20 ka), to verify the competing models. Here we present a suite of 58 cosmogenic exposure ages from 17 last-glacial ice limits in the Rangitata Valley of New Zealand, capturing an extensive record of glacial oscillations between 28-16 ka. The sequence shows that the local last glacial maximum in this region occurred shortly before 28 ka, followed by several successively less extensive ice readvances between 26-19 ka. The onset of Termination 1 and the ensuing glacial retreat is preserved in exceptional detail through numerous recessional moraines, indicating that ice retreat between 19-16 ka was very gradual. Extensive valley glaciers survived in the Rangitata catchment until at least 15.8 ka. These findings preclude the previously inferred rapid climate-driven ice retreat in the Southern Alps after the onset of Termination 1. Our record documents an early last glacial maximum, an overall trend of diminishing ice volume in New Zealand between 28-20 ka, and gradual deglaciation until at least 15 ka.
关键词：surface exposure dating ; global climate linkages
