scholarly journals Burial and thermal history of the Lower Palaeozoic petroleum source rocks at the SW margin of the East European Craton (Poland)

2019 ◽  
Author(s):  
Dariusz Botor ◽  
Jan Golonka ◽  
Aneta Anczkiewicz ◽  
István Dunkl ◽  
Bartosz Papiernik ◽  
...  
Keyword(s):  
Thermal History ◽  
East European Craton ◽  
Source Rocks ◽  
East European ◽  
History Of ◽  
Lower Palaeozoic

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>

Seismic profile LT-7 (northwest Poland): geological implications

1997 ◽  
Vol 134 (5) ◽  
pp. 653-659 ◽  
Author(s):  
RYSZARD DADLEZ
Keyword(s):  
Layer Structure ◽  
Seismic Profile ◽  
Suture Zone ◽  
East European Craton ◽  
Significant Differentiation ◽  
East European ◽  
Crystalline Crust ◽  
Lower Palaeozoic ◽  
Geological Implications ◽  
Four Blocks

Crystalline crust examined along the seismic profile LT-7 is subdivided into four blocks separated by distinct vertical fractures. The northeastern block belongs to the East European Craton (Baltica). Its three-layer structure is similar to that of the Svecofennian crust farther to the northwest. The southeastern block reveals typical, two-layer Variscan crust. Both central blocks have a peculiar structure not comparable with the crust of the Danish and North German areas: two lower layers, with velocities identical or close to that of the cratonic lower and middle layers, are extremely thin, and an upper layer, 8–11 km thick, shows surprisingly low velocities. This upper layer probably represents the folded and weakly metamorphosed Lower Palaeozoic sequences, although the connection with undeformed epicratonic cover cannot be excluded. Significant differentiation of crustal types in different segments of the Trans-European Suture Zone favours the concept of tectonostratigraphic terranes which collided with Baltica.

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