Geology Reference
In-Depth Information
7
Doing Rock Magnetic
Cyclostratigraphy
Abstract:
This chapter outlines the steps necessary to complete a successful rock
magnetic cyclostratigraphy study. Sampling strategy, sampling techniques,
sample preparation, rock magnetic measurements, time series analysis, and
tuning are described in the context of conducting a cyclostratigraphy study.
Identification of astronomically forced cycles, particularly the 405 kyr cycle of
long eccentricity, by the assignment of absolute time to the sedimentary sequence
by various techniques, concludes the chapter. This chapter provides a detailed,
step-by-step guide for conducting a rock magnetic cyclostratigraphy study. Much
of the background information necessary for understanding and analyzing rock
magnetic and cyclostratigraphy data sets has been provided in Chapters 2-6. The
goal of this chapter is to give researchers enough information to conduct a rock
magnetic cyclostratigraphy study, to make them cognizant of potential pitfalls,
and to point toward important resources for understanding their data. The sub-
sections of this chapter provide a general outline of the steps, in order, of com-
pleting a study.
7.1
Study Design
Before any fieldwork is conducted, important information needs to be col-
lected to plan the study and to determine whether the sedimentary sequence
being targeted is likely to give good results. Not all sedimentary rock types
are amenable to a rock magnetic cyclostratigraphy study. Of course, it is
important to have a sedimentary section that is likely to have been the result
of nearly continuous sedimentation. Small hiatuses and disconformities
probably exist in almost any sedimentary sequence, but the proper data
analysis, particularly tuning, can help the investigator see through the inev-
itably incomplete stratigraphic record (Sadler 1981). Platform carbonates
and hemipelagic marine sediments have yielded successful rock magnetic
