DATING BRITTLE FAULT-ZONE DEFORMATION - ADVANTAGES, LIMITATIONS, AND BIASES (Invited Presentation)

In the past five years large number of studies used in-situ U-Pb dating of fault-zone material, such as calcite, to date fault-zone activity. The new approach has several important advantages including, improved accuracy due to the in-situ approach, faster and simplified measurements relative to the isotope-dilution method and thus, better statistics and overall accuracy of temporal constraint on fault-zone activity.

To date, this method provided important temporal constraints on faults activation, initiation, propagation, interactions, and reactivation in active fault zone around the world. Limitations to this methodological approach include the notion that it does not apply to when faults were inactive but only for when faults were active, and thus the problematical use of partial records to infer changes in faults activity or reactivation through time. Several biases related to sampling, exposures, and climatic conditions, affecting calcite precipitations and preservations, further complicate the use of this method and requires in depth discussion.

In this talk I will argue that many of these biases can be overcome by including complimented isotopic-geochemistry and statistical analyses, while some limitations are inherent to this methodological approach.