Apatite fission track thermochronology: an overview of its potential and limitations in geomorphology

Abstract

The specific time window of apatite fission track thermochronology (AFTT) places it in a unique position to offer continuous time-temperature baseline histories for relatively stable shield, rift and passive margin environments, spanning several geological eras. Fission tracks anneal partially at temperatures between #110°C and #60°C and thereby provide information on residence times within specific levels of the crust. Most samples collected from these terrains, however, are usually found to have cooled out of the apatite partial annealing zone (APAZ) by the mid-Cenozoic at the latest. Owing to the stability, at geological timescales, of tracks at temperatures <60°C (i.e. within depths of 0-2.5 km at normal geothermal gradients), a significant loss of resolution must therefore be reckoned with at shallow, although geomorphologically crucial, crustal depths. Indeed, the Neogene and Quaternary are understood to have been most influential in generating the scenery of today, and a use of radiometric and stratigraphic techniques in a nested, multisystem approach can assist in bridging the resolution gap. This paper examines and illustrates, mostly with original examples, the uses and limitations of AFTT in addressing the response of Earth surface systems to event patterns in global tectonics, the controls of lithology and structure on denudation rates, the origin and evolution of passive margin escarpments, the mass-balanced reconstruction of palaeoelief, the use of apatites as tracers for understanding provenance in sediment routing systems, and the tempo (or episodicity) of denudation as postulated by W. M. Davis' canons of the 'geographical cycle'. Alongside efforts towards standardizing the supply of analytically robust AFT results in the laboratory, a more standardized geoscientific interpretation of AFT data is also desirable in order to build a consistent world base of geomorphic rates which can be made available to -and used with confidence by -non-AFTT specialists.sample population of tracks counted and measured in a PO Box 33,

Phanerozoic denudation across the Kola Peninsula, Northwest Russia: implications for long-term stability of Precambrian shield margins

“…Similar mismatches between geological and geomorphological indicators of denudation depths and AFT results have, however, been reported from other shield and platform areas (Gunnell, 2000;Hall & Bishop, 2002;Gunnell et al, 2003;Peulvast et al, 2008;Flowers & Kelley, 2011). Specifically, identification of reheating in AFT studies has led to appeals for burial by thick sedimentary covers of which few, if any traces remain (Gunnell, 2000). The constraints provided by long-term denudation indicators in areas such as the Kola Peninsula are a neglected component in the vigorous debates over the systematics and meaning of AFT analyses on the Fennoscandian Shield (Murrell & Andriessen, 2004;Hendriks & Redfield, 2005;Bonow et al, 2006;Larson et al, 2006;Kohn et al, 2009).…”

“…One reason for this disparity may lie in regional Early Jurassic reheating (Veselovskiy et al, 2013). Similar mismatches between geological and geomorphological indicators of denudation depths and AFT results have, however, been reported from other shield and platform areas (Gunnell, 2000;Hall & Bishop, 2002;Gunnell et al, 2003;Peulvast et al, 2008;Flowers & Kelley, 2011). Specifically, identification of reheating in AFT studies has led to appeals for burial by thick sedimentary covers of which few, if any traces remain (Gunnell, 2000).…”

“…If these dolerite dykes fed lava fields then Devonian plateau basalts may have originally extended across the Kola Peninsula towards remnants exposed in Timan (Mahotkin et al, 2000). Other basaltic lavas erupted from feeder dykes covered parts of northern Kola, emanating from igneous centres in the East Barents uplifting rocks proceed through a horizontally-stratified, thermal boundary layer (the apatite partial annealing zone or APAZ) and that past and present geothermal gradients can be defined (Gunnell, 2000). In the Kola Superdeep borehole (SG-3), the geothermal gradient is 18°C/km (Mottaghy et al, 2005).…”

“…Under these circumstances, most estimates of the depth, rate and timing of long-term denudation on glaciated shields rely heavily on AFT studies of regional thermochronology (Hendriks & Andriessen, 2002;Murrell & Andriessen, 2004;Ault et al, 2009). Yet interpretation of AFT data is strongly model dependent and requires integration with other regional geological data (Gunnell, 2000;Hall & Bishop, 2002). This paper examines integrated Phanerozoic denudation rates and patterns on the northern part of the Fennoscandian Shield in the Kola Peninsula, Northwest Russia (Fig.…”

Cenozoic uplift and denudation of southern Norway: insights from the North Sea Basin

“…This is important, as denudation may lag uplift by several tens of million years (Summerfield & Brown 1998). Moreover, AFTT is sensitive only to temperatures of minimum c. 60°C (depths > 2-3 km) and is thus generally not sensitive to late Cenozoic effects (Gunnell 2000), although inversion of the AFTT data may hint at late Cenozoic cooling histories (e.g. Rohrman et al 1995).…”