[Geoinfo] Invitación: Conferencia Dr. Olivier Galland, Lunes 1/4 - 11hs

[Daniel Yagupsky]

*EL INSTITUTO DE ESTUDIOS ANDINOS**Don Pablo Groeber*

*UBA – CONICET*

 *y*

*EL DEPARTAMENTO DE CIENCIAS GEOLÓGICAS-FCEyN-UBA*

Invitan a Ud. a asistir a la Conferencia:

*“Laboratory modeling of Magma Emplacement in the Brittle Crust**�*

Por el Doctor:

*Olivier Galland*

Universidad de Oslo, Oslo, Noruega

*Lunes 1 de Abril de 2019 a las 11hs.*

*Aula Aguirre del Depto. de Ciencias Geológicas, UBA*


Resumen de la charla:

The last decade or research highlighted that many sedimentary basins
worldwide host voluminous igneous intrusive complexes, mostly flat-lying
sills and laccoliths. These igneous intrusions have tremendous implications
on the petroleum system through maturation, circulation and trapping of
hydrocarbons.

 In this contribution, we focus on the structural and mechanical
implications of igneous intrusions on their sedimentary host rocks. When
magma is intruded into sedimentary rocks, it makes its space by pushing and
breaking the host rock, which can result in intense damage and fracturing.
Understanding and quantifying the distribution of such intrusion-induced
inelastic deformation pattern is essential to properly reveal the complex
processes governing the emplacement of sills and laccoliths. However, most
established models of sill and laccolith emplacement only account for
elastic rocks that break in tension, so that they are unable to predict the
distribution of fracture and damage around igneous intrusions due to the
plasticity of natural rocks.

 We investigated the effects of the brittle host rock cohesion on magma
emplacement and resulting fracture and damage distribution through series
of 3D and 2D scaled laboratory models. We show that high-cohesion host
rock, results in the emplacement of thin, sheet intrusions (sills,
cone-sheets). Conversely, low-cohesion host rock results in the emplacement
of massive intrusions (laccoliths, plugs). The deformation patterns
associated with sills and laccoliths are very different: fracturing and
damage associated with sill emplacement is restricted at the close vicinity
of the intrusion, whereas fracturing associated with laccolith emplacement
affects the overburden of the intrusion on a much larger scale.

In addition to the experimental approach, a series of numerical analyses
have been performed to quantify the inelastic deformation and damage of the
host rock near an overpressuried magmatic intrusion. Our results highlight
the importance of rock heterogeneity in controlling the failure mechanism
within the process zone of the system. By varying systematically the
characteristic wave-length and amplitude of the heterogeneity (stochastic
perturbation of the cohesion), we are able to show that localized dilatant
shear failure may be the dominant mechanism at play within the process
zone. For specific rock properties, the model result constrains the spatial
extent of the process zone and allows an interpretation of the fault
network orientation near the intrusion contact.

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