Ol Doinyo Lengai – August 28, 2019
If Dr. Seuss designed a volcano, Ol Doinyo Lengai would be it! From navigating mazes of 5-foot tall volcanic ash flows, to scooting along “cookies and cream” layers of volcanic flows, to hopping over volcanic “crevasses” still steaming, to witnessing lava bubbling* at the summit crater, this volcano is quite unique! In fact, the lava it erupts (called carbonatite) is some of the rarest on the planet .
Carbonatites are full of alkali elements – calcium, sodium, sometimes potassium – along with abundant carbon dioxide. Why is that odd? Most terrestrial magma is silicate, made from bonded chains of silicon and oxygen.
This has real consequences for the behavior of the magma. Those chains of silica in silicate magma are what give it some of its strength, where even the runniest basaltic lava is, in fact, quite viscous (resistant to flow). However, without the chains of silica to give the magma structure, carbonatite magma can have much lower viscosity, allowing for the strange “garden hose” eruptions that exemplify activity in the crater of Ol Doinyo Lengai.
The lack of structure and its composition also allows for carbonatite magma to erupt at much cooler temperatures than silicate magma. Your typical basalt might erupt at 1100-1200ºC, but carbonatite lava erupts at only ~480-590ºC.
Ol Doinyo Lengai was a steep climb and gained 5,500 vertical feet from the end-of-the-road where the “trail” started to the summit at the crater rim. Would we do it again? For such amazing and rare lava and out-of-this-world landscapes, yes!!
