UCL Earth Sciences


MSci students join international research project in Chile

8 December 2014

As part of their independent research project two MSci students, Joe Potten and Rebecca Pearce are taking part in a larger 4-year Chilean-funded project involving Tom Mitchell (UCL), Jose Cembrano and Gonzalo Yanez ,both from Pontificia Universidad Católica de Chile. This project aims to focus on the nature and tectono-magmatic significance of transverse crustal structures in the Andes, with some selected case studies from the Southern Volcanic Zone.


As part of the larger 4 year project, we plan to address the tectono-magmatic significance of NW and NE-striking fault long-lived basement structures, through a combination of field geology, geophysics and numerical modeling.  The aim is to  tackle the problem by selecting two outstanding case studies in the Andes of Central Chile. The two areas we plan to work on are the Tatara-San Pedro-Pellado volcanic complex- Laguna del Maule volcanic field Alignment and the Cortaderas-Chillán lineament. 

This December two of our current MSci students are conducting fieldwork as part of this project.  Rebecca Pearce is running gravity surveys at various scales in order to determine the subsurface extent and scale of some of these fault zone structures, and Joe Potten is collecting samples in order to conduct geochronological analyses and tie down the relative timing of various structures. This project is in close collaboration with Pieter Vermeesch, Andy Carter and Martin Rittner (also joining the December fieldwork). 

Joe Potten, our MSci student writes about his project: "The overall aim of my individual project is to determine the geometry, kinematics and timing of magmatic intrusions, in particular dyke intrusions, in the Transitional Southern Volcanic Zone of the Andes. All samples collected during this field-trip will be analysed in the Geochronology lab at UCL. 

There will be various methods of sample preparation before the zircons can be analysed and dated. These include obtains smaller pieces of the rock which will be crushed into a powder form. Next, the powder will undergo several methods mineral separation using liquids of different densities to the mineral as well as separation using the magnetic properties of certain minerals. The  results will be modelled in order to establish an age of these intrusions and how they relate to the overall kinematics of the study area."

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Major crustal faults and fold systems at convergent margins are commonly organized into margin parallel, high-strain domains that appear to be continuous over hundreds of kilometers. This first-order architecture shapes the structural grain of a given mountain belt and is thought to represent the long-term record of its deformation history. However, second-order transverse structures, cross-cutting the orogen main structural grain, are also common; e.g. in the Andes, for instance, they have been claimed to play a key role in the tectonic, magmatic and/or hydrothermal history. Although the relevance of these oblique-to the-orogen structures is widely recognized, surprisingly little is known regarding their nature, kinematics and timing and also their long and short-term tectono-magmatic role.  It is these structures that the project aims to focus on.