Experimental developments and application of carbon-14 and in situ cosmogenic nuclide dating techniques

Author:

Pigati, Jeffrey S.

Title:

Experimental developments and application of carbon-14 and in situ cosmogenic nuclide dating techniques

Periodical:

Department of Geosciences

Year:

2004

Volume:

Ph.D.

Pages:

188

Subject:

Glaciation Cosmogenic radionuclide dating Carbon-14 dating Mauna Kea

Summary:

The summit area of Mauna Kea, Hawaii was covered intermittently by ice caps during the Late Pleistocene. The maximum extents of the last two ice caps (older and younger Makanaka) were similar, reaching ∼800 m below the summit. We have developed a new chronology for these glaciations using cosmogenic ³⁶Cl which shows that the ice caps began retreating from their maximum extents at 23.3 ± 2.3 ka and 13.0 ± 0.9 ka, respectively, broadly coincident with the last glacial maximum and the Younger Dryas chronozone. The potential for using in situ cosmogenic ¹⁴C to determine surface exposure ages of Holocene landforms, quantify erosion rates, and decipher complex exposure histories when used in conjunction with other cosmogenic nuclides is well known. Before this potential can be realized, however, protocols for isolating and extracting in situ ¹⁴C must be developed. Analytical techniques have been developed previously to isolate in situ ¹⁴C from quartz and carbonate. Although these minerals can be found in most places on Earth, they are usually absent from basaltic terrains. To fill this gap, we conducted numerous chemical pretreatment experiments and step-heated extractions aimed at isolating and extracting in situ ¹⁴C from olivine. Our results suggest that step-heated extractions alone may be sufficient to isolate in situ ¹⁴C from olivine.

URL:

http://hdl.handle.net/10150/280735

Date:

2004

Collection:

Monographs