COMPLICATED THERMAL HISTORY OF THE LITHOSPHERIC MANTLE OF THE ANABAR REGION: RECONSTRUCTIONS BASED ON XENOCRYSTS FROM KIMBERLITES
The thermal history and thickness of the lithospheric mantlebeneath the kimberlite fields of the Eastern Anabar shield and adjacent territories of the Siberian craton were reconstructed based on the composition of clinopyroxene xenocrysts from the concentrate of kimberlite heavy fraction and mantle...
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| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Russian Academy of Sciences, Siberian Branch, Institute of the Earth's crust
2024-10-01
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| Series: | Геодинамика и тектонофизика |
| Subjects: | |
| Online Access: | https://www.gt-crust.ru/jour/article/view/1914 |
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| Summary: | The thermal history and thickness of the lithospheric mantlebeneath the kimberlite fields of the Eastern Anabar shield and adjacent territories of the Siberian craton were reconstructed based on the composition of clinopyroxene xenocrysts from the concentrate of kimberlite heavy fraction and mantle xenoliths. Garnet and spinel peridotites are most abundant in the lithospheric mantle beneath the five studied fields of the Siberian craton. Almost in all fields, the Mg# index of clinopyroxene decreases through depth. In the oldest Chomurdakh kimberlite field, both TiO2 and FeO contents vary slightly. The titanium oxide values markedly vary from 0 to 0.6 wt. % in the Triassic fields. The high titanium oxide contents in minerals are indicative of deepseated metasomatic transformations of lithospheric mantle blocks in the northern Yakutia kimberlite province. The geotherm was fitted to the PT data set in the Gtherm program with the model involved D. Hasterok and D. Champan. The thermal lithosphere beneath the studied fields retained the thermal thickness up to 260 km. In the period between 430 and 230 Ma, it underwent a significant metasomatic transformation resulting in the formation of highFe and highTi blocks. It appears, that the thermal thickness declined to 190–200 km only in the north of the Siberian craton during the Jurassic period. This assumption is verified by the values of lithosphere thickness beneath the northern Kuoika field. |
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| ISSN: | 2078-502X |