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Examining Fault Growth in High-Resolution Using Terrestrial Growth Strata, Se Pyrenees, Spain

James Carrigan
Earth and Environmental Sciences Department, Lehigh University, Bethlehem, PA, USA
[email protected]

Abstract

Foreland basins provide excellent record of the sediment from nearby tectonically active regions, but dating the deposition of these continental deposits is typically difficult. My research focuses on  a blind thrust anticline along the northern margin of the Ebro Basin. Growth strata in this anticline will be used to reconstruct the history of the underlying faults' slip. Magnetic minerals in these strata can be used as a proxy for climatic variations. Magnetite is a primary magnetic mineral during deposition, while hematite and geothite form during pedogenesis. Magnetite deposited in foreland basins vary due to changes in climate related to Milankovitch fluctuations on 400, 100, and 20kyr timescales. We will use anhysteretic remanent magnetization (ARM) as a method to measure these variations in magnetite concentration. ARM is useful because it is cheap and objective making processing large sample sets easy. Hematite and geothite will be acessed using thermal demagnetization of the samples. Additionally, oriented cores will be collected periodically to refine the exsisting magnetic reversal chronology. By using the change in magnetite as a basis for high-resolution time we aim to see changes in fault slip on the 104-105 yr timescales. The time scale over which surface processes vary has been suggested as a principle modulator of deformation. Determining the variations in fault slip will provide insight on connection between surficial processes and deformation. Understanding these processes in the Ebro will allow for application to all studies of fault related fold kinematics where high-resolutin chronologies provide clues to driving processes.

AAPG Search and Discovery Article #90199 © 2014 AAPG Foundation 2014 Grants-in-Aid Projects