The First Apatite Fission Track Data on the Siberian Traps Large Igneous Province: Signs of the Unrecognized Thermal Event or Thick Eroded Volcanic Pile?
Abstract
The Siberian Traps are the classic example of the Large Igneous Province and represent voluminous area of the basaltic magmatic activity. According to the recent isotopic data, emplacement of the main volume of the Siberian Traps occurred during 1-2 Myr at the Permian-Triassic boundary (about 251 Ma; Burgess and Bowring, 2015). However, the following thermal history of the Siberian platform is still poorly understood.
Here we present the first results of apatite fission track dating of the intrusions from different regions of the Siberian province. We analyzed in total 8 samples from the huge Padunskiy sill (the Angara-Taseeva syncline, southern part of the Siberian platform), Odikhincha and Guli alkaline-ultramafic massifs (Maymecha-Kotuy area, the north Siberian platform), and monzonites of the Kontay intrusion taken from the borehole in the Enisey-Khatanga basin about 40 km westward from the Guli massif. Padunskiy sill is dated by U-Pb (zircons) as 251.7-251.4 Ma (Burgess and Bowring, 2015); age of Guli massif is 250.2±0.3 Ma (U-Pb, baddeleyite; Kamo et al., 2003). As for Kontay intrusion, Rb-Sr dating yielded the age of 483±66 Ma (Zaytsev et al., 2018) however, signs of the partial disturbance of isotopic system were reported by authors. Samples from Odikhincha and Kontay intrusions, as well as from Padunskiy sill yielded AFT ages between 195.2 and 173.1 Ma with uncertainties (1σ) of ±11.7-13.8 Ma. Mean track lengths for all those samples lie in the range 13.76-14.49 µm and demonstrate the narrow unimodal distribution. Three samples from Guli are the remarkable exceptions, yielding ages between 231.2 and 250.1 Ma with 1σ of ±28.5-41.8 Ma. Early-Middle Jurassic AFT ages of Padunskiy sill, Odikhincha and Kontay massifs can be interpreted in three ways: 1) unrecognized thermal event, which took place both in the north and the south of the Siberian platform before J2; 2) continuous regional crust heating during the emplacement of the Siberian Traps with the subsequent slow cooling from T1 to J2; 3) burial of the analyzed intrusions under the thick volcanic pile of the Siberian Traps and their successive exhumation due to erosion. Our further goals are AFT dating of intrusions from other areas of the Siberian Traps and estimation of the eroded volume of volcanics. This work was supported by RFBR (grants 18-35-20058, 18-05-70094).- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.V31C0123L
- Keywords:
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- 0473 Paleoclimatology and paleoceanography;
- BIOGEOSCIENCES;
- 4912 Biogeochemical cycles;
- processes;
- and modeling;
- PALEOCEANOGRAPHY;
- 8137 Hotspots;
- large igneous provinces;
- and flood basalt volcanism;
- TECTONOPHYSICS;
- 8408 Volcano/climate interactions;
- VOLCANOLOGY