High-resolution ⁴⁰Ar/³⁹Ar study of Mount Avital, northern Golan: Reconstructing the interaction between volcanism and a drainage system and their impact on eruptive styles

We present a high-resolution ⁴⁰Ar/³⁹Ar data set of a volcanic complex at Mt. Avital, northern Golan, which experienced a transition from strombolian to phreatomagmatic activity. Previous studies attributed this transition to a change in the drainage basin of a nearby stream due to the damming by a lava flow, which resulted in flooding of the eruption site. In this study we determined the age of different volcanic phases and events in the history of Mt. Avital, as well as that of the damming flow, and examined the cause of the transition in light of the new ⁴⁰Ar/³⁹Ar ages. The ⁴⁰Ar/³⁹Ar results show that the history of Mt. Avital includes two main phases of volcanic activity, an early phase at ca. 800-600 ka and a late phase at 120-95 ka. Most of the activity of the late phase was continuous (within the ⁴⁰Ar/³⁹Ar error), including the transition to phreatomagmatic explosions, which occurred sometime between 115-107 ka, probably between 115-113 ka. The age of the damming flow is 115.6 ± 3.1 ka, which suggests that the volcanic activity immediately reacted to the change in the drainage basin dynamics. The activity culminated with lava flow eruptions, the latest at 100 ± 4 ka, either due to the establishment of the tuff ring levees, which prevented access of water to the eruption site, or due to the migration of activity to the northern part and then to the southern part of the complex.