Date

2015

Document Type

Thesis

Degree

Master of Science

Department

Earth and Environmental Sciences

First Adviser

Anastasio, David

Other advisers/committee members

Kodama, Kenneth; Parés, Josep

Abstract

This study develops a high-resolution chronostratigraphy age model based on magneticsusceptibility (χ) variations to determine folding rates recorded by Eocene-Oligocene synorogenic terrestrial growth strata of the Berga Conglomerate Formationnear Sant Llorenç de Morunys, NE Spain. This region was selected forits excellent preservation and exposure of synorogenic growth strata which allowsfor examination of deformation at high-resolution (20 kyr) time scales. The BergaConglomerate was sampled for rock magnetic, paleomagnetic, and cyclostratigraphyanalyses. Analysis of rock magnetic measurements indicate paramagneticphyllosilicates are the dominant minerals that control cyclostratigraphy in amixed mineral assemblage. Anisotropy of magnetic susceptibility (AMS) fabricsare most consistent with a fixed hinge flexural folding and transecting cleavagedeveloped in the foreland synclinal hinge. Paleomagnetic reversal stratigraphyprovided absolute time frame on folding at the million year timescale. Time seriesanalysis of variations shows statistically significant power in expected orbitalratios (long eccentricity, obliquity, and precession). A calibrated age model wasconstructed using variations tuned to obliquity (41 kyr) cycles, which focusespower into precession index bands and long eccentricity. The age model predictsthe onset of deformation at 33.85 Ma and shows that deformation and sedimentaccumulation rates were unsteady at 20 kyr time scales. Deformation rates rangefrom quiescent to 100°/Myr and are not related to changes in sediment accumulationrate. Modeled fault slip predicts variable displacement rates ranging from 115 -265 m/ Myr.

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