Age of Rocks and Peculiarities of the Formation of the Dariganga Volcanic Field, Southeastern Mongolia

The results of systematic geochronological (K–Ar) studies of rocks of the Dariganga volcanic field (DVF) composed of Late Cenozoic mafic lavas are presented. Four stages of its evolution are distinguished: the Middle–Late Miocene (>10 Ma), Late Miocene–Early Pliocene (7.8–3.5 Ma), Late Pliocene (2.8–2.6 Ma), and Pleistocene (<1.7 Ma). The products of these stages are regularly distributed within the volcanic field. The main volume of eruptions was related to the Late Miocene–Early Pliocene and Pleistocene stages. The northwestern part of the lava field as a lava plateau formed during the Late Miocene–Early Pliocene. The eruptions are related to a local structural depression, which originated under extension accompanying volcanism. The southeastern part of the DVF formed during the Pleistocene volcanic eruption. Volcanism accompanied the formation of the Khukhot-Ein-Nuru Ridge in the Nukut-Daban Uplift and was responsible for the morphological peculiarities of the volcanic cover. A typical feature of it includes the large multicentered shield volcanoes related to the axial zone of the ridge, as well as the elongated valley flows along both slopes. The peculiarities of the formation of the DVF and other volcanic areas of the Late Cenozoic intraplate volcanic province of Central and East Asia are compared. Their consistent evolution indicates that the formation of the DVF was controlled by the same geodynamic mechanisms as the formation of other volcanic areas of the province, namely, by the activity of a small mantle plume.