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Crustal thickening and doming induced by the emplacement of volcanic plumbing systems: case studies at back-arc volcanoes in the Neuquén Basin, Argentina

Ezequiel Lombardo1, Daniel Yagupsky2, Ernesto Cristallini2, Dougal A. Jerram3,4, Olivier Galland3

  • Affiliations: 1Chevron Argentina, Avenida Del Libertador 7208, C1429BMS Buenos Aires, Argentina; 2CONICET- IDEAN, Instituto de Estudios Andinos 'Don Pablo Groeber', Universidad de Buenos Aires, Buenos Aires, Argentina; 3NJORD Centre, University of Oslo, Norway; 4DougalEARTH Ltd., Solihull, Uk 

  • Presentation type: Talk

  • Presentation time: Thursday 16:00 - 16:15, Room R380

  • Programme No: 1.8.1

  • Theme 1 > Session 8

Abstract

Volcanic edifices in textbooks are typically represented as local accumulations of volcanic products generally building up from a near flat substratum. In this contribution, we present three volcanoes case studies and show that their substratum has been systematically uplifted by crustal doming. These case studies formed in the compressional back-arc tectonic setting of the Neuquén Basin, Argentina. These volcanic complexes built upon, and their shallow plumbing systems were emplaced into, the Mesozoic sedimentary strata of the Neuquén Basin. Borehole data and 3-dimensional seismic data acquired for hydrocarbon exploration show that the strata of the Mesozoic substratum underneath each volcanic complex exhibits a large, gentle domal structure of 500 to 1000 metres amplitude. The domal structures correlate in position and dimension with those of the volcanoes, which consist of a thin cover of volcanic products coating the underlying crustal dome. The volcanoes also show evidence of lower amplitude localized doming around individual and nested shallow intrusions. Our study suggests that the injection of volcanic plumbing systems in back-arc settings contributes to crustal thickening and doming of the Earth's surface. Such doming likely locally affects regional stresses, which may impact magma transport in the shallow crust and control the emplacement of radial dyke swarms, shallower sill intrusions, and enhance transport of magma to the surface. In general, our study highlights the effects of volcanic plumbing systems on the structure and stress in the Earth's crust, and the links from the deeper to the shallower parts of the system.