2015 SPA - David Cruset - Crestal graben fluid evolution during late growth stage of the Puig-reig anticline (South Pyrenean fold and thrust belt)

[This post is participating at the 2015 Student Presentation Awards at ICTJA]

Hello, my name is David Cruset and I am in the first year of my PhD in the Institute of Earth Sciences Jaume Almera - CSIC. The topic of my thesis is the fluid migration in the South Pyrenean fold and thrust belt, from Late Cretaceous to Oligocene. To deal with this objective, I will do petrographic studies and geochemical analyses of the products related with fluid flow and the structural characterization of the structures where these products were formed. The interest of this thesis is that fluids are important because they are responsible of heat and matter transport and are involved in ore deposition and hydrocarbon accumulations. In addition, the study of the diagenetic products related with fluid migration can shed light on the geodynamic evolution of a basin or orogen.

Fig. 1 Geological cross section of the frontal part of the South Pyrenean fold and thrust belt.

As a preliminary step, during the last year I have been studying the fluid flow in the Puig-reig anticline, one of the structures of the frontalmost part of the South Pyrenean fold and thrust belt (Fig. 1). This work shows how during the early folding deep hot meteoric fluids circulated along inverse and strike-slip faults, whereas during the main stage of folding cooler meteoric waters percolated downwards the normal faults formed by collapse of the crest of the anticline (Fig.2). This study reports the controls of fracturing on the palaeohydrology of folds during different stages of their evolution.

The comparison of the obtained results with those obtained in previous works by other authors in nearby areas will allow us to perform the fluid flow model of the frontal part of the South Pyrenean fold and thrust belt.

Fig. 2 Schemes of the structural and fluid flow evolution of the Puig-reig anticline. Red and blue arrows indicate fluid movement. No vertical exaggeration. A) Fluid flow during the early folding. Hot evolved meteoric fluids migrated along the main faults and more permeable sedimentary units. B) Fluid flow during the main stage of folding. During this event, local meteoric fluids circulated downwards the normal faults formed by outer arc extension and mixed with the evolved meteoric fluids. 

This work is supervised by Dr. Jaume Vergés (Group of Dynamics of The Litosphere - GDL, ICTJA - CSIC) and by Dr. Anna Travé (Grup de Geologia Sedimentària, Department of Geochemistry, Petrology and Geological Prospecting - UB).