[Caceres] Conditions for nanocrystals formation in Krafla shallow rhyolitic magma: A potential site for explosive eruptions

German Title: Conditions for nanocrystals formation in Krafla shallow rhyolitic magma: A potential site for explosive eruptions

Abbreviation: 414

Current Status: approved

Main Applicant:Dr. Francisco Caceres

Resources Recipient

Other Persons

Conveyor Begin: 1 March, 2021
Conveyor End:
Conveyor Duration: 24
Year: 2021


Krafla rhyolitic magma encountered at ~2100 m depth by wells related to geothermal exploration, in the frame of the IDDP project, opened new possibilities for unique research on magma reservoirs. The Krafla Magma Drilling Project (KMDP), within the priority program ICDP, was created to comprehend the origin as well as the physical, chemical and mechanical conditions of this magma under Krafla caldera. However, of great importance is to understand under what conditions this magma may erupt, which is the main objective that this project aims to contribute to resolve.
The project presented here is born as a novel idea based on recent results on the effect of nanocrystals on degassing and viscosity changes of Krafla rhyolitic magma, and silicic magma in general, and the implications for eruption explosivity these nanocrystals have. Magmatic nanocrystals or “nanolites” are a yet underreported phenomenon that has been shown crucial to determine explosivity of magma in volcanic eruptions. However, the mostly unknown conditions at which these magmatic crystals form and remain stable create the need to investigate their capacity to form in the rhyolitic magma at Krafla for the potential explosivity that may induce.
The general objective of this project is to determine the stability field and conditions required to form and sustain magmatic nanocrystals in pre- and (potential) syn-eruptive magma of Krafla, and the changes that these produce in magma properties. This will be studied through two experimental approaches, mimicking the conditions at which Krafla magma is stored. The oxidation state, pressure, temperature and time required to form and keep stable nanolites will be determined by performing highly controlled crystallisation experiments during magma cooling and stabilisation at variable P-T-t conditions using Krafla rhyolite material. Resultant material will be precisely analysed using cutting-edge methods to determine the presence, nature and extent of nanolites crystallisation. Rheology measurements will be performed to determine the extent of viscosity increase produced by different degree of nanolite crystallisation. Additionally, the physical process driving nanolite crystallisation from magma will be determined, i.e. crystallisation from a homogeneous liquid or immiscible liquids separation.
Preliminary work shows that nanolites can form in rhyolitic magma from Krafla. However, it is expected as a main outcome from this project to stablish a complete map of conditions suitable for nanolites crystallisation, unveiling a critical aspect of this magma not explored beforehand.