Cosmogenic nuclides: Beryllium-10 and Chlorine-36 in the West Antarctic Ice Sheet Divide ice core and advances in accelerator

• Main Author: Woodruff, Thomas Edward
• Other Authors: Caffee, Marc W.
• Format: Text
• Language: English
• Published: Purdue University 2012
• Subjects: Physics|Geochemistry; Antarctic; West Antarctic Ice Sheet; Greenland; Antarc*; ice core; Ice Sheet
• Online Access: https://docs.lib.purdue.edu/dissertations/AAI3545463

Polar ice cores continue to provide a wealth of information about the history of Earth's environment. Cosmogenic radionuclides, produced in the atmosphere by cosmic rays and deposited on ice sheets, carry clues to the nature and variability of solar activity and the geomagnetic field in the past. They can also be used to independently measure the snow accumulation rate and provide chronological markers to compare with other paleoarchives such as sea sediment cores. The present work details measurements of 10Be and 36Cl in the West Antarctic Ice Sheet Divide ice core. We have established a new chemical processing line at Purdue University for this work and demonstrated that it produces results identical to a sister lab at UC Berkeley. 10Be and 36Cl have been measured in the top 560 m of core at ∼12 and 24 year resolution. In addition we have measured 10Be at annual resolution from 1586–2006 AD. We find good agreement between our results and a 10Be record from Greenland and with the historic sunspot record. In addition, work is described on the development of several new upgrades to the Purdue Rare Isotope Measurement Lab accelerator mass spectrometry facility. Two new detectors for 14C and 10Be have been constructed as well as a new gas-filled magnet system. The new detectors have capabilities comparable to those of the previous detector and have been easier and faster to use. The gas-filled magnet system is not yet ready for routine use but preliminary tests have been performed and further development of the system is underway.