scholarly journals Deconvolution of fission-track length distributions and its application to dating and separating pre- and post-depositional components

Geochronology ◽  
2021 ◽  
Vol 3 (2) ◽  
pp. 561-575
Author(s):  
Peter Klint Jensen ◽  
Kirsten Hansen
Keyword(s):  
Least Squares ◽  
Covariance Matrix ◽  
Thermal History ◽  
Prior Information ◽  
Fission Track ◽  
Length Distribution ◽  
Track Length ◽  
Fission Tracks ◽  
Apatite Crystals ◽  
Thermal Histories

Abstract. To enable the separation of pre- and postdepositional components of the length distribution of (partially annealed) horizontal confined fission tracks, the length distribution is corrected by deconvolution. Probabilistic least-squares inversion corrects natural track length histograms for observational biases, considering the variance in data, modelization, and prior information. The corrected histogram is validated by its variance–covariance matrix. It is considered that horizontal track data can exist with or without measurements of angles to the c axis. In the latter case, 3D histograms are introduced as an alternative to histograms of c-axis-projected track lengths. Thermal history modelling of samples is not necessary for the calculation of track age distributions of corrected tracks. In an example, the age equations are applied to apatites with predepositional (inherited) tracks in order to extract the postdepositional track length histogram. Fission tracks generated before deposition in detrital apatite crystals are mixed with post-depositional tracks. This complicates the calculation of the post-sedimentary thermal history, as the grains have experienced different thermal histories prior to deposition. Thereafter, the grains share a common thermal history. Thus, the extracted post-depositional histogram without inherited tracks may be used for thermal history calculation.

scholarly journals Age distribution of horizontal fission tracks

2021 ◽  
Author(s):  
Peter Klint Jensen ◽  
Kirsten Hansen
Keyword(s):  
Least Squares ◽  
Covariance Matrix ◽  
Thermal History ◽  
Prior Information ◽  
Age Distribution ◽  
Track Length ◽  
Fission Tracks ◽  
Apatite Crystals ◽  
Distribution Calculation ◽  
Thermal Histories

Abstract. Equations for the distribution of age versus length of partially annealed horizontal fission tracks in apatite is presented. Probabilistic least–squares inversion corrects natural track length histograms for observational biases considering the variance of data, modelization, and prior information. The corrected histogram is validated by its variance–covariance matrix. It is considered that horizontal track data can be with or without measurements of angles to the c–axis. In the last case, 3D–histograms are introduced as an alternative to histograms of c–axis projected track lengths. Thermal history modeling of samples is not necessary for track age distribution calculation. In an example the age equations are applied to apatites with pre–depositional (inherited) tracks, to extract the post–depositional track length histogram. Fission tracks generated before deposition in detrital apatite crystals are mixed with post–depositional tracks. This complicates the calculation of the post– sedimentary thermal history as the grains have experienced different thermal histories until deposition. Thereafter the grains share a common thermal history. The extracted post–depositional histogram without inherited tracks may be used for thermal history calculation.

Some calculations relevant to thermal annealing of fission tracks in apatite

1988 ◽  
Vol 419 (1857) ◽  
pp. 305-321 ◽  
Keyword(s):  
Conditional Distribution ◽  
Fission Track ◽  
Length Distribution ◽  
Track Length ◽  
Apatite Crystal ◽  
Routine Practice ◽  
Fission Tracks ◽  
Line Segments ◽  
Segment Model ◽  
Arbitrary Plane

Calculations in stochastic geometry are applied to the geological problem of analysing the statistical distribution of fission tracks in an apatite crystal, when information is available only by plane sampling. The feature of particular interest is the effect of anisotropy, in the sense of dependence of track length on orientation. Using a realistic Poisson line-segment model, we obtain formulae for the density of line segments intersecting an arbitrary plane and for the length distributions of confined tracks, semi-tracks and projected semi-tracks in terms of the conditional distribution of length given orientation. These formulae are used to explain and quantify the effect of anisotropy seen in experimental data from fission track annealing studies. We argue that track orientations, in addition to lengths, carry potentially useful information. For confined tracks, we recommend that both length and angle to the c -axis be measured as routine practice. For projected semi-tracks, where it is much harder to extract useful information from the observed length distribution, the measurement of angle, in addition to length, may prove fruitful, particularly when confined tracks are scarce.

Thermal history of the Mackenzie Plain, Northwest Territories, Canada: Insights from low-temperature thermochronology of the Devonian Imperial Formation

2019 ◽  
Vol 132 (3-4) ◽  
pp. 767-783 ◽  
Author(s):  
Jeremy W. Powell ◽  
Dale R. Issler ◽  
David A. Schneider ◽  
Karen M. Fallas ◽  
Daniel F. Stockli
Keyword(s):  
Low Temperature ◽  
Thermal History ◽  
Fission Track ◽  
Length Distribution ◽  
Sedimentary Basins ◽  
Track Length ◽  
Data Sets ◽  
Burial History ◽  
Cooling History ◽  
History Of

Abstract Devonian strata from the Mackenzie Plain, Northern Canadian Cordillera, have undergone two major burial and unroofing events since deposition, providing an excellent natural laboratory to assess the effects of protracted cooling history on low-temperature thermochronometers in sedimentary basins. Apatite and zircon (U-Th)/He (AHe, ZHe) and apatite fission track (AFT) thermochronology data were collected from seven samples across the Mackenzie Plain. AFT single grain ages from six samples span the Cambrian to Miocene with few Neoproterozoic dates. Although there are no correlations between Dpar and AFT date or track length distribution, a relationship exists between grain chemistry and age. We calculate the parameter rmr0 from apatite chemistry and distinguish up to three discrete kinetic populations per sample, with consistent Cambrian–Carboniferous, Triassic–Jurassic, Cretaceous, and Cenozoic pooled ages. Fifteen ZHe dates range from 415 ± 33 Ma to 40 ± 3 Ma, and AHe dates from 53 analyses vary from 225 ± 14 Ma to 3 ± 0.2 Ma. Whereas several samples exhibit correlations between date and radiation damage (eU), all samples demonstrate varying degrees of intra-sample date dispersion. We use chemistry-dependent fission track annealing kinetics to explain dispersion in both our AFT and AHe data sets and detail the thermal history of strata that have experienced a protracted cooling history through the uppermost crust. Thermal history modeling of AFT and AHe samples reveals that the Devonian strata across the Mackenzie Plain reached maximum burial temperatures (∼90 °C–190 °C) prior to Paleozoic to Mesozoic unroofing. Strata were reheated to lower temperatures in the Cretaceous to Paleogene (∼65 °C–110 °C), and have a protracted Cenozoic cooling history, with Paleogene and Neogene cooling pulses. This thermal information is compared with borehole organic thermal maturity profiles to assess the regional burial history. Ultimately, these data reflect the complications, and possibilities, of low-temperature thermochronology in sedimentary rocks where detrital variance results in a broad range of diffusion and annealing kinetics.

Thermal history modelling of the western margin of the Bohemian Massif using high-resolution apatite fission-track thermochronology

2020 ◽  
Author(s):  
Lucie Novakova ◽  
Raymond Jonckheere ◽  
Bastian Wauschkuhn ◽  
Lothar Ratchbacher
Keyword(s):  
High Resolution ◽  
Bohemian Massif ◽  
Thermal History ◽  
Fission Track ◽  
Track Length ◽  
Apatite Fission Track ◽  
Fission Track Thermochronology ◽  
Length Measurements ◽  
Thermal Histories ◽  
Fission Track Ages

<p>The Naab area is situated on the western border of the Bohemian Massif, 60 km south of the KTB (Kontinentalen Tiefbohrung). The main super-deep borehole of the KTB reached a depth of 9,101 meters in the Earth's continental crust. The fission-track data for the KTB and the Naab area present contrasting signatures. The apatite fission-track ages in the upper section of the KTB borehole and surrounding area are in the range 50-70 Ma (Wagner et al., 1994; Wauschkuhn et al., 2015). The apatite fission-track ages of the Naab basement are older than those of the KTB area, and span a broader range: 120-200 Ma (Vercoutere, 1994). The distributions of the confined-track lengths range from unimodal over skewed and mixed to bimodal, with mean lengths in the range 11-13 µm. In broad terms, this can be interpreted as that the Naab samples contain both an older and younger (in particular pre- and post-late Cretaceous) fission-track population. The aim of our research is to investigate the applicability of lab-based models to geological data, using improved measurement techniques.</p><p>We studied eighteen samples dated by Vercoutere (1994) from the Palaeozoic basement and seven large rock samples from the Rotliegend strata north of the Luhe fault.  We intend to extend the confined-track length measurements of Vercoutere (1994), aiming to achieve higher resolution through methodological innovations made possible by computer-controlled motorized microscopes. Improved statistics increase the resolution of the modelled thermal histories, which permits to better distinguish systematic from statistical differences between the modelled palaeotemperatures and geological estimates. Experiments have shown that the rate of length increase permits to distinguish older from younger tracks (Jonckheere et al., 2017). This allows us to distinguish between tracks formed before and after the Late Cre­taceous to Palaeocene exhumation. The etch rate of a confined track is also an indicator of its individual thermal history, supplementing the information gleaned from its etchable length under fixed conditions. We compiled a comprehensive, high-resolution confined-track-length dataset. The Naab thermal histories were determined using modern modelling algorithms, implementing the most recent empirical equations.</p><p><strong>References</strong></p><p>Jonckheere R., Tamer M., Wauschkuhn F., Wauschkuhn B., Ratschbacher L., 2017. Single-track length measurements of step-etched fission tracks in Durango apatite: Vorsprung durch Technik.American Mineralogist 102, 987-996.</p><p>Vercoutere C., 1994. The thermotectonic history of the Brabant Massif (Belgium) and the Naab Basement (Germany):   an apatite fission track analysis. Ph. D. thesis, Universiteit Gent, pp. 191.</p><p>Wagner G.A., Hejl E., Van Den Haute P., 1994. The KTB fission-track project: Methodical aspects and geological implications. Radiation Measurements 23, 95-101.</p><p>Wauschkuhn B., Jonckheere R., Ratschbacher L., 2015. The KTB apatite fission-track profiles: building on a firm foundation? Geochimica et Cosmochimica Acta 167, 27-62.</p>

FISSION TRACK ANALYSIS: A NEW TOOL FOR THE EVALUATION OF THERMAL HISTORIES AND HYDROCARBON POTENTIAL

1983 ◽  
Vol 23 (1) ◽  
pp. 93 ◽  
Author(s):  
A. J. W. Gleadow ◽  
I. R. Duddy ◽  
J. F. Lovering
Keyword(s):  
Fission Track ◽  
Sedimentary Basins ◽  
Track Length ◽  
Fission Track Analysis ◽  
Fission Tracks ◽  
Annealing Zone ◽  
Oil Generation ◽  
Thermal Histories ◽  
Fission Track Ages ◽  
Track Analysis

Fission track dating is a new approach to the interpretation and quantitative modelling of thermal histories of sedimentary basins for hydrocarbon resource evaluation. This technique depends on the observation that annealing of fission tracks in minerals, like the generation and maturation of hydrocarbons, is a function of temperature and time. The temperature interval over which track annealing occurs in the mineral apatite, a common detrital mineral in sedimentary rocks, is virtually identical (60° to 125°C) with that required for the maximum generation of liquid hydrocarbons. Fission tracks in apatite separated from a rock sample thus contain a record of its heating in the oil generation window. The pattern of apatite fission track ages, together with detailed analyses of the distributions of track lengths, will yield information on thermal history unobtainable by other methods. The unique advantage of the fission track method is that it can give information not only on maximum palaeotemperatures, but also their variation through time.Fission tracks in detrital zircon and sphene are stable to higher temperatures (200° - 300°C) than in apatite enabling limits to be placed on maximum temperatures reached in sedimentary basins, as well as giving important information on sedimentary provenance.In the Otway and Gippsland Basins fission track ages and lengths determined on apatites, and ages determined on sphenes and zircons, have been used to reconstruct the thermal histories of different areas. Ages and track lengths of apatites from deep wells in the Otway Basin show the expected down hole decrease reaching zero apparent age where present well temperatures are about 125°C. The shape of the track length distribution is characteristic of the position of a sample within the track annealing zone and hence the oil generation window. Flaxmans-1 in the Otway Basin has an age profile indicating that present temperatures are at or very near the maximum experienced. In Eumeralla-1 sediments that lie above the present-day track annealing zone show clear evidence of track annealing in the past, indicating that temperatures have decreased. This is consistent with the relatively small amount of post-Early Cretaceous sedimentation observed in this well compared to Flaxmans-1.Fission track analysis thus has the potential of giving a new, quantitative perspective on the temperature history of rocks, which should have an important impact on techniques of petroleum exploration.

Resolving thermal histories via multi-kinetic apatite fission track data: A case study from Phanerozoic strata within the Peel Plateau NWT, Canada

2021 ◽  
Author(s):  
Jennifer Spalding ◽  
Jeremy Powell ◽  
David Schneider ◽  
Karen Fallas
Keyword(s):  
Low Temperature ◽  
Thermal History ◽  
Fission Track ◽  
Sedimentary Basins ◽  
Source Rocks ◽  
Apatite Fission Track ◽  
Petroleum Systems ◽  
History Of ◽  
Thermal Histories ◽  
Peel Plateau

<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>

Apatite fission-track age correction and thermal history analysis from projected track length distributions

1993 ◽  
Vol 103 (1-4) ◽  
pp. 157-169
Author(s):  
M. Grivet ◽  
M. Rebetez ◽  
N. Ben Ghouma ◽  
A. Chambaudet ◽  
R. Jonckheere ◽  
...  
Keyword(s):  
Thermal History ◽  
Fission Track ◽  
Track Length ◽  
Apatite Fission Track ◽  
History Analysis ◽  
Age Correction

Track length distribution and thermal history of apatites

1985 ◽  
Vol 10 (3) ◽  
pp. 406
Author(s):  
A. Chambaudet ◽  
M. Mars ◽  
M. Rebetez ◽  
M. Rossi
Keyword(s):  
Thermal History ◽  
Length Distribution ◽  
Track Length ◽  
History Of

Reproducibility of apatite fission-track length data and thermal history reconstruction

2009 ◽  
Vol 284 (3-4) ◽  
pp. 504-515 ◽  
Author(s):  
Richard A. Ketcham ◽  
Raymond A. Donelick ◽  
Maria Laura Balestrieri ◽  
Massimiliano Zattin
Keyword(s):  
Thermal History ◽  
Fission Track ◽  
Track Length ◽  
Apatite Fission Track ◽  
Length Data

scholarly journals Simulating sedimentary burial cycles – Part 2: Elemental-based multikinetic apatite fission-track interpretation and modelling techniques illustrated using examples from northern Yukon

2021 ◽  
Author(s):  
Dale R. Issler ◽  
Kalin T. McDannell ◽  
Paul B. O'Sullivan ◽  
Larry S. Lane
Keyword(s):  
Thermal History ◽  
Fission Track ◽  
Learning Algorithm ◽  
Random Search ◽  
Apatite Fission Track ◽  
Significance Level ◽  
Aft Model ◽  
Heating And Cooling ◽  
Thermal Histories ◽  
Consistent Assessment

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.

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