Thermomechanical models with surface processes: Low-Temperature Thermochronology predictions for model calibration

Author(s):  
Romain Beucher ◽  
Louis Moresi ◽  
Roderick Brown ◽  
Claire Mallard

<p>State of the art thermo-mechanical models have become very efficient at testing scenarios of tectonic evolution but uncertainties on the rheologies and the complexity of the have so far limited the potential to quantitatively predict uplift and subsidence. Coupling thermo-mechanical models to landscape evolution models remains challenging and require careful validation and better integration of field data to prevent error in interpretation.</p><p> </p><p>Low temperature thermochronology has been extensively used to quantitatively constrain the thermal histories of rocks. It can provide important information on tectonic uplift (or subsidence) by measuring the erosional (or burial) response and can also map the spatial and temporal pattern of geomorphic response of a landscape.</p><p> </p><p>We use the temperature evolution of our coupled thermo-mechanical models with surface processes to predict Apatite fission track data (Ages and Track lengths distributions). The aim is to provide a direct means of comparison with actual empirical thermochronometric data which will allow different model scenarios and/or model parameter choices to be robustly tested.</p><p>We present a series of 3D coupled models (Underworld / Badlands) of Rifts and the associated Apatite Fission Track predicted by the thermal evolution of the rocks exhumed to the surface. We compare models predictions to existing thermochronological transects across passive margins.</p><p> </p><p>We discuss the technical challenges in obtaining sufficiently high resolution temperature field and other associated challenges that need to be addressed to satisfactory apply our model to natural examples.</p>

2021 ◽  
Author(s):  
Jennifer Spalding ◽  
Jeremy Powell ◽  
David Schneider ◽  
Karen Fallas

<p>Resolving the thermal history of sedimentary basins through geological time is essential when evaluating the maturity of source rocks within petroleum systems. Traditional methods used to estimate maximum burial temperatures in prospective sedimentary basin such as and vitrinite reflectance (%Ro) are unable to constrain the timing and duration of thermal events. In comparison, low-temperature thermochronology methods, such as apatite fission track thermochronology (AFT), can resolve detailed thermal histories within a temperature range corresponding to oil and gas generation. In the Peel Plateau of the Northwest Territories, Canada, Phanerozoic sedimentary strata exhibit oil-stained outcrops, gas seeps, and bitumen occurrences. Presently, the timing of hydrocarbon maturation events are poorly constrained, as a regional unconformity at the base of Cretaceous foreland basin strata indicates that underlying Devonian source rocks may have undergone a burial and unroofing event prior to the Cretaceous. Published organic thermal maturity values from wells within the study area range from 1.59 and 2.46 %Ro for Devonian strata and 0.54 and 1.83 %Ro within Lower Cretaceous strata. Herein, we have resolved the thermal history of the Peel Plateau through multi-kinetic AFT thermochronology. Three samples from Upper Devonian, Lower Cretaceous and Upper Cretaceous strata have pooled AFT ages of 61.0 ± 5.1 Ma, 59.5 ± 5.2 and 101.6 ± 6.7 Ma, respectively, and corresponding U-Pb ages of 497.4 ± 17.5 Ma (MSWD: 7.4), 353.5 ± 13.5 Ma (MSWD: 3.1) and 261.2 ± 8.5 Ma (MSWD: 5.9). All AFT data fail the χ<sup>2</sup> test, suggesting AFT ages do not comprise a single statistically significant population, whereas U-Pb ages reflect the pre-depositional history of the samples and are likely from various provenances. Apatite chemistry is known to control the temperature and rates at which fission tracks undergo thermal annealing. The r<sub>mro</sub> parameter uses grain specific chemistry to predict apatite’s kinetic behaviour and is used to identify kinetic populations within samples. Grain chemistry was measured via electron microprobe analysis to derive r<sub>mro</sub> values and each sample was separated into two kinetic populations that pass the χ<sup>2</sup> test: a less retentive population with ages ranging from 49.3 ± 9.3 Ma to 36.4 ± 4.7 Ma, and a more retentive population with ages ranging from 157.7 ± 19 Ma to 103.3 ± 11.8 Ma, with r<sub>mr0</sub> benchmarks ranging from 0.79 and 0.82. Thermal history models reveal Devonian strata reached maximum burial temperatures (~165°C-185°C) prior to late Paleozoic to Mesozoic unroofing, and reheated to lower temperatures (~75°C-110°C) in the Late Cretaceous to Paleogene. Both Cretaceous samples record maximum burial temperatures (75°C-95°C) also during the Late Cretaceous to Paleogene. These new data indicate that Devonian source rocks matured prior to deposition of Cretaceous strata and that subsequent burial and heating during the Cretaceous to Paleogene was limited to the low-temperature threshold of the oil window. Integrating multi-kinetic AFT data with traditional methods in petroleum geosciences can help unravel complex thermal histories of sedimentary basins. Applying these methods elsewhere can improve the characterisation of petroleum systems.</p>


1999 ◽  
Vol 11 (4) ◽  
pp. 451-460 ◽  
Author(s):  
Joachim Jacobs ◽  
Frank Lisker

New apatite fission-track (AFT) ages from Heimefrontfjella and Mannefallknausane indicate that the Mesoproterozoic basement and Permian sedimentary cover rocks were heated to c. 100°C during the Mesozoic. Heating was due to the burial by up to 2000 m of Jurassic lavas at c. 180 Ma, when the area was affected by the Bouvet/Karoo hot spot. Near the developing coastline, the lava pile was quickly eroded and in part deposited on the continental shelf as pebbly and coarse-grained volcaniclastic sandstones. The AFT data indicate that farther inland the lava pile was not eroded until c. 100 Ma, and the Palaeozoic unconformity between the Mesoproterozoic basement and Permo–Carboniferous sedimentary rocks as a reference plane remained at temperatures of c. 80°C. Formation of an up to 800 m b.s.l. deep graben in from Heimefrontfjella as well as flexural uplift and rapid denudational cooling of the not extended crust from Heimefrontfjella southwards occurred at c. 100 Ma. It is speculated that a period of major plate reorganisation and new rifting at c. 100 Ma is responsible for affecting a much wider continental margin as far inland as Heimefrontfjella and producing a total relief in excess of 3500 m.


2021 ◽  
Author(s):  
Dale R. Issler ◽  
Kalin T. McDannell ◽  
Paul B. O'Sullivan ◽  
Larry S. Lane

Abstract. Compositionally dependent apatite fission track (AFT) annealing is a common but underappreciated cause for age dispersion in detrital AFT samples. We present an interpretation and modelling strategy that exploits multikinetic AFT annealing to obtain thermal histories that can provide more detail and better resolution compared to conventional methods. We illustrate our method using a Permian and a Devonian sample from the Yukon, Canada, both with complicated geological histories and long residence times in the AFT partial annealing zone. Effective Cl values (eCl; converted from rmr0 values), derived from detailed apatite elemental data, are used to define AFT statistical kinetic populations with significantly different total annealing temperatures (~110–245 °C) and ages that agree closely with the results of age mixture modelling. These AFT populations are well-resolved using eCl values but exhibit significant overlap with respect to the conventional parameters, Cl content or Dpar. Elemental analyses and measured Dpar for Phanerozoic samples from the Yukon and Northwest Territories confirm that Dpar has low precision and that Cl content alone cannot account for the compositional and associated kinetic variability observed in natural samples. An inverse multikinetic AFT model, AFTINV, is used to obtain thermal history information by simultaneously modelling multiple kinetic populations as distinct thermochronometers with different temperature sensitivities. A nondirected Monte Carlo scheme generates a set of statistically acceptable solutions at the 0.05 significance level and then these solutions are updated to the 0.5 level using a controlled random search (CRS) learning algorithm. The smoother, closer-fitting CRS solutions allow for a more consistent assessment of the eCl values and thermal history styles that are needed to satisfy the AFT data. The high-quality Devonian sample (39 single grain ages and 202 track lengths) has two kinetic populations that require three cycles of heating and cooling (each subsequent event of lower intensity) to obtain close-fitting solutions. The younger and more westerly Permian sample with three kinetic populations only records the latter two heating events. These results are compatible with known stratigraphic and thermal maturity constraints and the QTQt software produces similar results. Model results for these and other samples suggest that elemental-derived eCl values are accurate within the range, 0–0.25 apfu (rmr0 values of 0.73–0.84), which encompasses most of the data from annealing experiments. Outside of this range, eCl values for more exotic compositions may require adjustment relative to better constrained apatite compositions when trying to fit multiple kinetic populations. Our results for natural and synthetic samples suggest that an element-based multikinetic approach has great potential to increase the temperature range and resolution of thermal histories dramatically relative to conventional AFT thermochronology.


2021 ◽  
Author(s):  
Chen Wu ◽  
et al.

Table S1. Summary of the lower thermochronometry published dataset in the Eastern Kunlun Range. Figure S1. Apatite fission-track radial plots from RadialPlotter by Vermeesch (2009) of the study samples.


2010 ◽  
Vol 61 (1) ◽  
pp. 19-27 ◽  
Author(s):  
Martin Danišík ◽  
Milan Kohút ◽  
Igor Broska ◽  
Wolfgang Frisch

Thermal evolution of the Malá Fatra Mountains (Central Western Carpathians): insights from zircon and apatite fission track thermochronologyWe apply zircon and apatite fission track thermochronology (ZFT and AFT, respectively) to the Variscan crystal-line basement of the Malá Fatra Mts (Central Western Carpathians) in order to constrain the thermal history. The samples yielded three Early Cretaceous ZFT ages (143.7±9.6, 143.7±8.3, 135.3±6.9 Ma) and one Eocene age (45.2±2.1 Ma), proving that the basement was affected by a very low-grade Alpine metamorphic overprint. Although the precise timing and mechanisms of the overprint cannot be unequivocally resolved, we propose and discuss three alternative explanations: (i) a Jurassic/Cretaceous thermal event related to elevated heat flow associated with extensional tectonics, (ii) early Late Cretaceous thrusting and/or (iii) an Eocene orogeny. Thermal modelling of the AFT cooling ages (13.8±1.4 to 9.6±0.6 Ma) revealed fast cooling through the apatite partial annealing zone. The cooling is interpreted in terms of exhumation of the basement and creation of topographic relief, as corroborated by the sedimentary record in the surrounding Neogene depressions. Our AFT results significantly refine a general exhumation pattern of basement complexes in the Central Western Carpathians. A younging of AFT ages towards the orogenic front is evident, where all the external massifs located closest to the orogenic front (including Malá Fatra Mts) were exhumed after ~13 Ma from temperatures above ~120 °C.


2007 ◽  
Vol 19 (1) ◽  
pp. 97-106 ◽  
Author(s):  
Frank Lisker ◽  
Christopher J.L. Wilson ◽  
Helen J. Gibson

Analysis of five basement samples from the Vestfold Hills (East Antarctica) reveals pooled apatite fission track (FT) ages ranging from 188 to 264 Ma and mean lengths of 13.7 to 14.9 μm. Quantitative thermal histories derived from these data give consistent results indicating onset of cooling/denudation began sometime prior to 240 Ma, with final cooling below 105°–125°C occurring between 240 and 220 Ma (Triassic). A Cretaceous denudation phase can be inferred from the sedimentary record of the Prydz Bay offshore the Vestfold Hills. The two denudational episodes are likely associated with Palaeozoic large-scale rifting processes that led to the formation of the adjacent Lambert Graben, and to the Cretaceous Gondwana break-up between Antarctica and India. Subsequent evolution of the East Antarctic passive continental margin likely occurred throughout the Cenozoic based on the depositional record in Prydz Bay and constraints (though tentative) from FT data.


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