title: The early rise and late demise of New Zealand's last glacial maximum.
abstract: 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.
authors: Institute for Geography and Geology, University of Greifswald, 17489 Greifswald, Germany; henrik.rother@gmail.com.
authors: Henrik
authors: H
authors: Rother
authors: Australian Nuclear Science and Technology Organisation, Menai, NSW 2234, Australia;
authors: David
authors: D
authors: Fink
authors: School of Geography, Planning and Environmental Management, The University of Queensland, St. Lucia Campus, Brisbane, QLD 4072, Australia;
authors: James
authors: J
authors: Shulmeister
authors: Australian Nuclear Science and Technology Organisation, Menai, NSW 2234, Australia;
authors: Charles
authors: C
authors: Mifsud
authors: Moultrie Geology, Banyo, QLD 4014, Australia; and.
authors: Michael
authors: M
authors: Evans
authors: Department of Geological Sciences, University of Canterbury, Christchurch, New Zealand.
authors: Jeremy
authors: J
authors: Pugh
keywords: global climate linkages; surface exposure dating