Apatite thermochronology in modern geology

Abstract

Fission-track and (U-Th-Sm)/He thermochronology on apatites are radiometric dating methods that refer to thermal histories of rocks within the temperature range of 408-125 8C. Their introduction into geological research contributed to the development of new concepts to interpreting time-temperature constraints and substantially improved the understanding of cooling processes within the uppermost crust. Present geological applications of apatite thermochronological methods include absolute dating of rocks and tectonic processes, investigation of denudation histories and long-term landscape evolution of various geological settings, and basin analysis.

Thermal and exhumation history of the central Rwenzori Mountains, Western Rift of the East African Rift System, Uganda

“…Information on the thermal history of apatite is stored in two archives: the etch pit areal density at an artificially polished internal surface, and the length distribution of horizontal confined tracks (e.g. Wagner and Van den haute 1992; Lisker et al 2009, and literature cited therein). Fission of 238 U generates spontaneous fission-tracks that are metastable in relation to temperature.…”

“…As rocks are exhumed through the Earths' crust, they cool through the thermal field from hot sub-surface temperatures to significantly colder surface temperatures (Reiners and Shuster 2009). Well-suited tools to track this cooling history are various low-temperature thermochronology methods, which yield the time at which the rock has passed through a certain isotherm (Batt and Brandon 2002;Reiners and Ehlers 2005;Lisker et al 2009). Relevant information is stored in heavy minerals, such as apatite and zircon, and can be revealed by different low-temperature thermochronology techniques.…”

Long-term cooling history of the Albertine Rift: new evidence from the western rift shoulder, D.R. Congo

“…For details of the analytical procedures, we refer to Reiners and Nicolescu (2006) and Bauer et al (2013) and literature cited therein. More detailed summaries on LTT techniques are provided by Reiners and Brandon (2006), Lisker et al (2009) and Green et al (2013).…”

Phosphate Rocks

“…29 Crucially, fission tracks are semi-stable features that can self-repair (shorten and eventually disappear) by the process known as annealing at a rate that is a function of both time and temperature. The extent of any track shortening (exposure to elevated temperatures) in a sample can be quantified by examining the distribution of fission-track lengths [6], [85], [86], [87], [88].…”

“…They are ideal for investigating the tectonic and climatedriven surficial interactions that take place within the top few (<5 km) kilometers of the Earth's crust. These processes govern the landscape evolution, influence the climate and generate the natural resources essential to the well-being of mankind [85], [95].…”