Crustal Exhumation of Plutonic and Metamorphic Rocks: Constraints from Fission-Track Thermochronology

The geologic interpretation of the detrital thermochronology record within a stratigraphic framework, with examples from the European Alps, Taiwan and the Himalayas

“…2) (Braun et al, 2006;Reiners and Brandon, 2006;Herman et al, 2013;Willett and Brandon, 2013). As it is well known from thermochronology applied to basement rocks, interpretation of all thermochronologic ages as representing cooling through the Tc isothermal surface during exhumation is often too simplistic (e.g., Gleadow, 1990;Villa, 1998, Williams et al, 2007Baldwin et al, 2019). During exhumation, rocks transit from a zone characterized by the complete loss of decay products, or total annealing of fission tracks (at higher temperatures), to a zone characterized by near-complete retention of decay products or near-complete retention of fission tracks (at lower temperatures) (Fig.…”

“…Ar-Ar can be introduced by syntectonic (re)crystallization of micas that have grown at temperatures lower than the isotopic closure of the Ar-Ar system, for example during low-grade metamorphism (e.g., Baldwin et al, 2019;Malusà, 2019). In metamorphic rocks, micas generally show microtextural evidence of petrological disequilibrium (Challandes et al, 2008;Glodny et al, 2008).…”

Exhumation and tectonic history of inaccessible subglacial interior East Antarctica from thermochronology on glacial erratics

“…Presently, nearflat lying strata of the Beacon Supergroup dip gently under the East Antarctic Ice Sheet with the front of the range marked by normal faults usually striking subparallel to the range front, and in places escarpment retreat is documented 43,48 . Generally, the youngest thermochronology ages representing the greatest (and more recent) exhumation lie along the rift flank adjacent to the coast, with ages getting older with increasing elevation and reflective of less exhumation along the inland flank of the TAM 42 . Overall, compared to young active orogens, exhumation is very slow, but episodes of faster exhumation have occurred.…”

“…There is a large body of low-temperature thermochronology data from the TAM that we can compare to the new data from interior East Antarctica 26,32,[35][36][37][38][39][40][41][42][43][44][45][46][47][48] . The TAM are rift-flank mountains adjacent to the West Antarctic rift system, reaching elevations exceeding 4000 m, but overall the geology of these mountains is relatively straightforward 30,49 .…”

Ongoing exhumation of the Taiwan orogenic wedge revealed by detrital apatite thermochronology: The impact of effective mineral fertility and zero-track grains

“…Low-temperature thermochronological methods such as apatite fission-track (AFT) thermochronology (Wagner and van den Haute 1992) provide crucial information to constrain the exhumation history of orogenic belts. In young active accretionary prisms largely consisting of low-grade metamorphic rocks, the use of AFT thermochronology is commonly hampered by the occurrence of apatite grains with low U concentration [U] yielding few spontaneous fission tracks, if any (e.g., Kirstein et al 2010;Baldwin et al 2019). Data obtained from only a few fission tracks in sporadic apatite crystals are affected by large analytical errors (e.g., Galbraith 2005) and may thus lead to poorly constrained geological interpretations, especially when a conspicuous population of apatite grains lacking spontaneous tracks is not properly accounted for.…”