Date of Graduation

2016

Document Type

Thesis

Degree Type

MS

College

Eberly College of Arts and Sciences

Department

Geology and Geography

Committee Chair

Jaime Toro

Committee Co-Chair

Ryan Shackleton

Committee Member

Kathy Benison

Committee Member

Mark Evans

Committee Member

Shikha Sharma

Abstract

Five systematic joint sets (J1-J5) have been observed at and around the Sant Corneli anticline in the south-central Spanish Pyrenees. These joint sets have been identified and grouped primarily on observed orientations in the field by two previous studies; however, syntectonic strata and cross-cutting relationships do not fully constrain the timing of these sets. This lack of timing constraints has resulted in two differing interpretations regarding the timing of each joint set. Understanding the conditions (i.e. pressure, temperature) of fracture filling cements at the time of cement formation can provide direct evidence for fluid evolution and migration at the time of formation, with direct implications regarding the timing of the fractures. The conditions of vein cement formation can be determined through detailed petrography, fluid inclusion microthermometry, and stable isotope analyses of the vein cements. Petrographic observations of the J1 and J2 sets indicate that the veins are characterized by drusy calcite cement, followed by fibrous to elongate blocky calcite cement and small blocky calcite cement, and exhibit no iron oxides. The J3, J4 and J5 veins are characterized by drusy calcite cement, small blocky calcite cement and large blocky calcite cement. Although J3 does not exhibit any iron oxides, the J4 and J5 samples do contain iron oxides. Late quartz cement is observed in the J1, J3 and J4 samples; because these samples were taken from the same stratigraphic sequence, the presence of the late quartz cement indicates that fluids became restricted at some time. Although there were significant fluid inclusions present within the vein samples analyzed, no fluid inclusion data was acquired because the fluid inclusions were too small to accurately distinguish phase changes during analyses. However, petrography of the fluid inclusions indicates that there were multiple generations of fluids passing through these veins. Carbon and oxygen stable isotope analyses indicate that the J1 and J3 sets were possibly open fracture networks, while the J2, J4 and J5 sets were most likely closed systems. The origins of the fluids for each joint set remains unknown, however, due to the lack of temperature data during vein formation.

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