TY - JOUR
T1 - Optical dating of coarse-silt sized quartz from loess: Evaluation of equivalent dose determinations and SAR procedural checks
AU - Roberts, H. M.
N1 - Roberts, H.M. (2006). Optical dating of coarse-silt sized quartz from loess: Evaluation of equivalent dose determinations and SAR procedural checks. Radiation Measurements, 41: 923-929.
PY - 2006/8/1
Y1 - 2006/8/1
N2 - This study discusses the values of equivalent dose (D
e) determined for samples taken for optical dating from a loess section at Loveland, Iowa, North America. A modified single-aliquot regenerative-dose (SAR) procedure was applied to quartz grains of 35-50 μ m diameter which were isolated using hydrofluorosilicic acid (H
2SiF
6). 'Preheat plots' were constructed to select appropriate D
e values for use in subsequent age determinations. The D
e values of the younger (Peoria loess) samples varied little with preheat temperatures between 160 and 300
{ring operator} C. However, the older (Pisgah Formation) samples showed a decrease in D
e values with increasing preheat temperature, by as much as a factor of two. Interestingly, both younger and older samples could recover a known laboratory administered radiation dose for a range of preheat temperatures. These apparently contradictory findings present a dilemma regarding which D
e values are the most appropriate to use for dating the samples. The behaviour of the samples is examined to investigate the cause of the variations in D
e values with preheat temperature for older samples. In addition, two modified SAR procedures were tested in an attempt to generate more reproducible D
e values. The data from the three SAR methods are examined, and the question of how to discriminate between D
e values is discussed. This study demonstrates that preheat temperature can play a significant role in the determination of D
e values. The use of plots of normalised luminescence signal (L
x / T
x) versus preheat temperature is proposed to supplement dose recovery tests and preheat plateau tests.
AB - This study discusses the values of equivalent dose (D
e) determined for samples taken for optical dating from a loess section at Loveland, Iowa, North America. A modified single-aliquot regenerative-dose (SAR) procedure was applied to quartz grains of 35-50 μ m diameter which were isolated using hydrofluorosilicic acid (H
2SiF
6). 'Preheat plots' were constructed to select appropriate D
e values for use in subsequent age determinations. The D
e values of the younger (Peoria loess) samples varied little with preheat temperatures between 160 and 300
{ring operator} C. However, the older (Pisgah Formation) samples showed a decrease in D
e values with increasing preheat temperature, by as much as a factor of two. Interestingly, both younger and older samples could recover a known laboratory administered radiation dose for a range of preheat temperatures. These apparently contradictory findings present a dilemma regarding which D
e values are the most appropriate to use for dating the samples. The behaviour of the samples is examined to investigate the cause of the variations in D
e values with preheat temperature for older samples. In addition, two modified SAR procedures were tested in an attempt to generate more reproducible D
e values. The data from the three SAR methods are examined, and the question of how to discriminate between D
e values is discussed. This study demonstrates that preheat temperature can play a significant role in the determination of D
e values. The use of plots of normalised luminescence signal (L
x / T
x) versus preheat temperature is proposed to supplement dose recovery tests and preheat plateau tests.
KW - Coarse-silt
KW - Loess
KW - Loveland Iowa
KW - Optically stimulated luminescence (OSL)
KW - Procedural checks
KW - Quartz
KW - Single-aliquot regenerative-dose (SAR)
UR - http://www.scopus.com/inward/record.url?scp=33750024060&partnerID=8YFLogxK
U2 - 10.1016/j.radmeas.2006.05.021
DO - 10.1016/j.radmeas.2006.05.021
M3 - Article
SN - 1350-4487
VL - 41
SP - 923
EP - 929
JO - Radiation Measurements
JF - Radiation Measurements
IS - 7-8
ER -