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| Titel |
Towards OSL-thermochronology, a new thermochrometer of very low closure temperature |
| VerfasserIn |
Frédéric Herman, Benny Guralnik, Frank Preusser, Sally Lowick, Edward Rhodes |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250057028
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| Zusammenfassung |
| Thermochronology is the study and measurement of the time-temperature history of rocks
during cooling. In practice, it provides estimates of the time since the rocks passed through a
given closure temperature window. Given that the thermal field of the uppermost crust is
sensitive to the topography, systems of low closure temperature can provide information on
the history of surface evolution as well as timing of tectonic processes. As a consequence,
systems such as apatite (U-Th)/He dating, which has a closure temperature of about
700C, have received widespread development and application. Recently, a novel
thermochronologic method, based on optically stimulated luminescence (OSL) dating has
been introduced (Herman et al., 2010). This innovative approach appears to have a closure
temperature of about 30-40 °C, opening a new window of research on the latest
stage of exhumation of rocks towards the surface. This system has the potential
to enable quantification of geologic and/or geomorphic processes at a timescale
comparable to that of Quaternary climate cycles. Besides its remarkable thermal
properties, OSL-thermochronology also has the advantage of the relative ease of making
measurements and the ubiquity of the minerals used: quartz, feldspar and potentially
zircon.
We present here a series of luminescence measurements made on samples from the
KTB borehole in Germany and the Southern Alps of New Zealand. The results
of the analysis from the KTB samples exhibit a clear temperature dependence:
samples from temperature lower than 30 °C are saturated while those from higher
temperature are reset. The samples from New Zealand illustrate how this new technique
can be used to constrain rates of erosion and relief change within a single glacial
cycle.
Herman F., E.J. Rhodes, J. Braun and L. Heiniger (2010) Uniform erosion rates and relief
amplitude in the Southern Alps of New Zealand, as revealed from OSL-thermochronology.
Earth and Planetary Science Letters, doi:10.1016/j.epsl.2010.06.019 |
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