Thermal history of the Siberian platform: Apatite Fission-Track data from the Permian-Triassic magmatic complexes

The largest continental igneous province, the Siberian Traps, was formed within the Siberian platform at the Paleozoic-Mesozoic boundary, ca. 252 million years ago. Despite the continuous and extensive investigation of the duration and rate of trap magmatism on the Siberian platform, these questions are still debated. Moreover, the post-Paleozoic thermal history of the Siberian platform is almost unknown. This study aims to reconstruct the thermal history of the Siberian platform during the last 250 Myr using the low-temperature thermochronometry. We have studied intrusive complexes from different parts of the Siberian platform, such as the Kotuy dike, the Odikhincha, Magan and Essey ultrabasic alkaline massifs, the Norilsk-1 and Kontayskaya intrusions, and the Padunsky sill. We use apatite fission-track (AFT) thermochronology to assess the time since the rocks were cooled below 110&#8451;. Obtained AFT ages (207-173 Ma) are much younger than available U-Pb and Ar/Ar ages of the traps. This pattern might be interpreted as a long cooling of the studied rocks after their emplacement ca. 250 Ma, but this looks quite unlikely because contradicts to the geological observations. Most likely, the rocks were buried under a thick volcanic-sedimentary cover and then exhumed and cooled below 110&#8451; ca. 207-173 Ma. Considering the increased geothermal gradient up to 50&#8451;/km at that times, we can estimate the thickness of the removed overlying volcanic-sedimentary cover up to 207-173 Ma as about 2-3 km.The research was carried out with the support of RFBR (grants 20-35-90066, 18-35-20058, 18-05-00590 and 18-05-70094) and the Program of development of Lomonosov Moscow State University.

Download Full-text

Thermal history of the Guli pluton (north of the Siberian platform) according to apatite fission-track dating and computer modeling

Geodynamics & Tectonophysics ◽

10.5800/gt-2020-11-1-0464 ◽

2020 ◽

Vol 11 (1) ◽

pp. 75-87

Author(s):

M. S. Myshenkova ◽

V. A. Zaitsev ◽

S. Thomson ◽

A. V. Latyshev ◽

V. S. Zakharov ◽

...

Keyword(s):

Computer Modeling ◽

Siberian Platform ◽

Alternative Model ◽

Fission Track ◽

Sedimentary Cover ◽

Fission Track Dating ◽

Apatite Fission Track ◽

First Results ◽

History Of ◽

Apatite Fission Track Dating

We present the first results of fission-track dating of apatite monofractions from two rock samples taken from the Southern carbonatite massif of the world’s largest alkaline ultrabasic Guli pluton (~250 Ma), located within the Maymecha-Kotuy region of the Siberain Traps. Based on the apatite fission-track data and computer modeling, we propose two alternative model of the Guli pluton's tectonothermal history. The models suggest (1) rapid post-magmatic cooling of the studied rocks in hypabyssal conditions at depth about 1.5 km, or (2) their burial under a 2-3 km thick volcano-sedimentary cover and reheating above 110°C, followed by uplift and exhumation ca. 218 Ma.

Download Full-text

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

10.5194/egusphere-egu21-3135 ◽

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

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 &#177; 5.1 Ma, 59.5 &#177; 5.2 and 101.6 &#177; 6.7 Ma, respectively, and corresponding U-Pb ages of 497.4 &#177; 17.5 Ma (MSWD: 7.4), 353.5 &#177; 13.5 Ma (MSWD: 3.1) and 261.2 &#177; 8.5 Ma (MSWD: 5.9). All AFT data fail the &#967;2 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 rmro parameter uses grain specific chemistry to predict apatite&#8217;s kinetic behaviour and is used to identify kinetic populations within samples. Grain chemistry was measured via electron microprobe analysis to derive rmro values and each sample was separated into two kinetic populations that pass the &#967;2 test: a less retentive population with ages ranging from 49.3 &#177; 9.3 Ma to 36.4 &#177; 4.7 Ma, and a more retentive population with ages ranging from 157.7 &#177; 19 Ma to 103.3 &#177; 11.8 Ma, with rmr0 benchmarks ranging from 0.79 and 0.82. Thermal history models reveal Devonian strata reached maximum burial temperatures (~165&#176;C-185&#176;C) prior to late Paleozoic to Mesozoic unroofing, and reheated to lower temperatures (~75&#176;C-110&#176;C) in the Late Cretaceous to Paleogene. Both Cretaceous samples record maximum burial temperatures (75&#176;C-95&#176;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.

Download Full-text