Geochemistry of Dominant LowTi Basalts of the Siberian

Geochemistry of Dominant Low-Ti Basalts of the Siberian Traps and Subduction-Related Model of Their Origin Ivanov A. V. Institute of the Earth’s Crust, Siberian Branch, Russian Academy of Sciences 1. Flood basalt geochemistry 2. 1. 1. Columbia River & 1. 2. Siberian Traps 2. Subduction-related model for flood basalts (Siberian Traps)

Columbia river Os-isotope data are after Chesley and Ruiz (1998)

Columbia river Data are plotted after Hooper and Hawkesworth (1993)

Columbia river Data are plotted after Hooper and Hawkesworth (1993)

Columbia river

Columbia river High-Mg basalts of Klyuchevskoi volcano

Siberian Traps Pangea

Siberian Traps Ages are for ‘basalts’ only !

Siberian Traps Approximate size of the Columbia River flood basalts

Siberian Traps Noril’sk

Siberian Traps Upper Morongovsky subsuite to Samoedsky suite basalts are not contaminated Saddle Mountains Imnaha Data are plotted after Wooden et al. (1993)

Siberian Traps Data are plotted after Wooden et al. (1993)

Siberian Traps

Siberian Traps

Siberian Traps Subduction signatures are more prominent

Model After Ohtani (2005)

Model Based on Bina et al. (2001), Litasov and Ohtani (2003), Hirschmann et al. (2005)

Siberian Traps 2300 km Transbaikalian belt (Andean-type orogen)

Model Transbaikalian belt

Model Siberian Traps, Noril’sk event

Model Siberian Traps, Tunguska event

Conclusions 1. Primitive mantle-derived flood basalts (with Siberian Traps and Columbia River as examples) show similarities with typical island-arc basalts. They are remarkably different with ocean island basalts. 2. Flood basalt origin can be explained by waterrecycling through transition zone of mantle via stagnated (by depth) subduction.

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