Lower Permian basaltic agglomerate from the Tsengel River valley, Mongolian Altai

• DOI: 10.5564/mgs.v51i0.1457
• Publication Date: 2020-12-22T11:31:59Z
• Authors: Kristýna Hrdličková; Altanbaatar Battu...; Pavel Hanžl; Alice Zavřelová; Jitka Míková
• Keywords: Late Devonian extinction; Devonian; Flood basalt

A new occurrence of Permian volcanic and volcaniclastic rocks in the Mongolian Altai south Main Lineament was described between soums Tugrug Tseel Gobi-Altai aimag. Studied vitrophyric pyroxene basalt lies a layer agglomerate amygdaloidal lavas, which is part NE–SW trending subvertical sequence varicolored siltstones Tsengel River valley. This high-Mg enriched large ion lithophile elements, Pb Sr depleted Nb Ta. LA-ICP-MS dating on 44 spots reveals several concordia clusters. The whole rock geochemistry sample fits arc characteristic geotectonic discrimination diagrams. Dominant zircon data yield Upper Carboniferous magmatic ages 304.4 ± 2.3 288.6 1.9 Ma. Two smaller clusters Devonian (376 4.7 Ma) to Lower (351.9 3.5 indicate probably contamination ascending material. Youngest Triassic age found three morphologically differing grains reflects lead loss. Described lava represents sub-aerial volcanism environment developed over N dipping subduction zone southwestern Mongolia time span from Uppermost during terminal stage its activity.