Post - Depositional Diagenesis and Chemical Remanent Magnetization - Paleomagnetism of Sedimentary Rocks: Process and Interpretation - page 77

(Temporal sense of folding)

NW SE

1.Folding (toward the foreland)

2.Remagnetization (short event relative to folding)

(Permian Remagnetization)

3. Continued folding (after remagnetization)

(Temporal sense of folding)

Pre Syn

Post

Fig. 6.6 Model for the formation of pre-, syn- and post-folding remagnetizations in the Appalachians due to the Kiaman age
remagnetization event (Stamatakos et al . 1996). Based on the paleomagnetic poles from the remagnetized rocks, the
remagnetization occurred over a relatively short 20 million year period between 275 and 255 Ma.

study of transects of remagnetized rocks in New York
and in Tennessee/Alabama. They observed that the
remagnetization was related to the degree of diage-
netic alteration of clay minerals and that Fe was
derived for secondary magnetic minerals from the illi-
tization of smectites. We will consider this mechanism
in more detail in the following section on remagnetiza-
tion caused by clay diagenesis. In addition, McCabe
et al . (1989) saw evidence of what they called a remag-
netization 'shadow' where the postulated basinal fl uids
went deep, avoiding shallower, younger Paleozoic
rocks, because the highly impermeable Chattanooga
Shale defl ected the fl uids. Elmore et al . (1993) exam-
ined the spatial relationships of remagnetization in the
Ordovician Viola Limestone of Oklahoma to veins in
the rock. They found pervasive remagnetization in sec-

ondary magnetite of the Viola, but that a remagnetiza-
tion residing in secondary hematite decreased with
distance from the veins. Fluid inclusion and 87 Sr iso-
topic studies showed that the secondary fl uids purport-
edly causing the remagnetization were warm, saline
and radiogenic.
Finally, studies since McCabe & Elmore ' s (1989)
review article show that there are examples of: Late
Paleozoic Kiaman-age remagnetized rocks in miogeo-
synclinal carbonate rocks from Nevada, Utah and
California carried by secondary magnetite (Gillett &
Karlin 2004); remagnetized Precambrian rocks in the
Rocky Mountains with the magnetization carried by
secondary hematite (Geissman & Harlan 2002); and
remagnetized Lower Carboniferous carbonates from
the Craven Basin of northern England (McCabe &