Bibliographic Details
| Title: |
Picrodolerite Dikes of the Naryn River: Age, Composition, and Position in the Geological History of Southern Tuva (Central Asian Orogenic Belt). |
| Authors: |
Yarmolyuk, V. V.1,2 (AUTHOR), Kozlovsky, A. M.1 (AUTHOR) amk@igem.ru, Moroz, U. A.1 (AUTHOR), Nikiforov, A. V.1 (AUTHOR) |
| Source: |
Doklady Earth Sciences. Jun2024, Vol. 516 Issue 2, p954-963. 10p. |
| Subject Terms: |
*OROGENIC belts, *MID-ocean ridges, *DIABASE, *PERIDOTITE, *MAGMAS, *AGE |
| Geographic Terms: |
TUVA (Russia) |
| Abstract: |
New evidence of the Early Silurian sublithospheric magmatic activity in the eastern part of the Altai–Sayan orogen has been obtained. This activity occurred between large-scale mantle-derived magmatic episodes of the Middle–Late Ordovician and Devonian. It involved high-Mg (15–22 wt % MgO) picritic dolerite dikes of the Naryn complex in the western part of the Tuva–Mongolian Superterrane. The dike complex consists of simple picrodolerite dikes and those combined with a central picrodolerite zone and granitoids at contacts with mingling relationships between contrasting rocks. The picrodolerite geochemical signature is similar to enriched basalts of the mid-ocean ridges or intraplate regions and is indicative of a sublithospheric mantle source. Initial picrodolerite melts were formed at a depth of about 120–140 km, a temperature of 1600–1640°C, and a melting degree of up to 20% at a dry peridotite source. These values are consistent with the conditions of the hot spot magmas origin. Granitoids from the combined dikes had a crustal geochemical signature and were formed due to the anatexis of the Tuva–Mongolian Superterrane host rocks initiated by the picrodolerite intrusion. The U–Pb zircon age (SHRIMP-II) of leucogranite from the combined dike is 439 ± 3 Ma interpreted as the age of the Naryn dike complex. The Early Silurian mantle-derived magmatic activity of the Southeastern Tuva most likely caused the migration of the Siberian paleocontinent over the African mantle hot field. [ABSTRACT FROM AUTHOR] |
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