Milankovitch Forcing Theory - Rock Magnetic Cyclostratigraphy

Geology Reference

In-Depth Information

(a)

1.0

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0.0

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.1

Cycles/kyr

(b)

JUL

AUG

SEP

150

100

OCT

50

NOV

DEC

JAN

FEB

0

−50

MAR

APR

MAY

JUN

−100

−150

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.1

Cycles/kyr

ETP/Mar

ETP/May

ETP/Jul

ETP/Sept

ETP/Nov

ETP/Jan

ETP/Apr

ETP/Jun

ETP/Aug

ETP/Oct

ETP/Dec

ETP/Feb

Figure 5.4 4π prolate multitapered coherency (a) and cross-phase (b) spectra of the ETP versus monthly insolation

at 35° North from 40 to 36 Ma, time increasing toward the present. ETP and monthly insolation were computed

using Analyseries 2.0.4.2 (Paillard et al. 1996); spectra were computed with cmtm.m by Peter Huybers (see Appendix).

High coherency and stable cross phase is detected in the eccentricity, obliquity, and precession index bands, as well as

in minor, high-frequency precession index bands at (14 kyr) −1 and (13 kyr) −1 . Source: Kodama, Anastasio, Newton,

Pares & L. A. Hinnov 2010. Reproduced with permission of John Wiley & Sons, Inc.

Figure 5.5 Timescales for the Arguis ARM cyclostratigraphy. 2π prolate multitaper power spectra on the left refer to

untuned and tuned ARM series on the right. (a) Original ARM series in the stratigraphic domain. (b) The ARM time

series according to GTS2004 magnetic reversal ages (GPTS2004). (c) The 405 kyr-tuned ARM time series, with 405 kyr tie

points indicated by vertical blue lines. The lowpass Taner filter isolates 405 kyr cyclicity. (d) La2004 eccentricity-tuned time

series, first iteration, shown with blue vertical lines between ARM minima and eccentricity minima. (e) La2004 eccentricity

tuning, second iteration. Minima and maxima of the lowpass filtered ARM series are tied to minima and maxima of the

eccentricity series, shown with blue vertical tie lines. (f ) La2004 precession index tuning of bandpassed precession band

of the eccentricity, second iteration tuned ARM series. (g) Depth-time transformation from each tuning. (h) ARM series

referring to the power spectra; the bottom-most series is the La2004 precession index-tuned accumulation rate series

defined at ~10 kyr intervals. The time picks were made using the “linage” function in Analyseries (Paillard et al. 1996);