Magmas concentrate metals, and magma fluids traveling into the surrounding wall rock plant the seeds for mineral growth.
This magma is rich in carbon dioxide gas, which produces explosive eruptions.
Massive sulfide deposits may also form in other settings where water circulates in rocks near cooling magma .
Until the rocks crystallized, uranium atoms could move freely through the molten magma from which they formed, and decayed uranium could be replenished.
An aircraft will soon fly over the lava dome to test for the presence of carbon dioxide and sulfur dioxide, signs that magma might be building up.
The continuing uplift of the caldera rim can be explained by the restricted size of the magma 's exit route.
Melts form at the highest temperatures and lowest pressures resulting in large volumes of tholeiitic magma that form shield volcanoes such as Mauna Loa.
From beneath the dome, the magma could combine with pressurized gases and steam to trigger an eruption, Pierson said.
Injections of new batches of mafic magma have been important for triggering dacitic eruptions.
As old oceanic crust was consumed in the trenches, new magma rose and erupted along the spreading ridges to form new crust.