US EPA

7128202 

Journal Article 

Progressive Growth of the Cerro Bayo Cryptodome, Chachahuen Volcano, Argentina-Implications for Viscous Magma Emplacement 

Burchardt, S; Mattsson, T; Palma, JO; Galland, O; Almqvist, B; Mair, K; Jerram, DA; Hammer, O; Sun, Y; , 

2019 

Yes 

Journal of Geophysical Research: Solid Earth
ISSN: 2169-9313
EISSN: 2169-9356 

AMER GEOPHYSICAL UNION 

WASHINGTON 

124 

8 

7934-7961 

10.1029/2019JB017543 

WOS:000491283500021 

Cryptodome and dome collapse is associated with volcanic hazards, such as explosive eruptions, pyroclastic density currents, and volcanic edifice collapse. The study of the growth and evolution of volcanic domes provides vital information on the link between dome growth and the development of weakness zones that may cause collapse. The Cerro Bayo cryptodome is superbly exposed in the eroded Miocene Chachahuen volcano in the Neuquen basin, Argentina. Cerro Bayo is a >0.3-km(3) trachyandesitic cryptodome that intruded within the uppermost kilometer of the Chachahuen volcano. Here we investigate the emplacement of the Cerro Bayo cryptodome using structural mapping, photogrammetry and measurement of magma flow indicators, brittle deformation features, and magnetic fabrics with anisotropy of magnetic susceptibility. Magma flow fabrics near the margin are concentric and indicate contact-parallel flow and internal inflation of the body. Magmatic and magnetic fabrics and fracture patterns in the interior of the cryptodome are more complex and outline several structural domains. These domains are separated by magmatic shear zones that accommodated intrusion growth. The shear zones locally overprint the earlier formed concentric fabric. The nature of the structural domains shows that the emplacement of Cerro Bayo occurred in three stages that resemble the endogenous to exogenous growth of volcanic domes. The formation of magmatic shear zones during cryptodome formation may have a profound effect on cryptodome stability by creating weakness zones that increase the risk of collapse. 

magma emplacement; cryptodome; laccolith; magma rheology; volcanic plumbing systems