Page 325 - Whole Earth Geophysics An Introductory Textbook For Geologists And Geophysicists

307 ridges. East

Studies geod ey spreading rate of mid-ocean results in narrow anomalies. b) broader

Paleomagnetic Pe ee (50-150 km/Ma), creating a

Ridge Ridge , a ee used to infer the (20-30 km/Ma) from spreading of 5-15 cm/a (a). time span as in

Spreading Spreading § por The widths of magnetic anomalies can be a) Mid-Atlantic Ridge. Slow-spreading rate of 2-3 cm/a Broader anomalies result over the same

- - of new lithosphere
Slow Fast 9,22

a) b) FIGURE Pacific Rise. region

years.
Million closer inclination region on remanent 9.24b).
= the (terrane)
MY by permission of Prentice-Hall. Inc., magnetizations of of (Fig. field
magnetic anomalies. magnetic The latitude block crustal inclination magnetic

Reprinted horizontally; 9.4a). magnetic the the If the latitude, present

1995. oriented steeper (Fig. indicates 9.24a), (Fig. different Earth’s

Interpretation World map showing the age of oceanic lithosphere determined from Hamblin/Christiansen, © magnctizations be would thus layer deposited a to drifts of that from

Magnetic Paleocene (56-65 MY) Cretaceous (65148 MY) "| Late surasaic (148-157 MY) ] aacore Jurassic (157-178 MY) ed. by remanent poles sedimentary was layer formed differ would

[| * 7th
[ ss [ magnetic a for the layer
Chapter3 to Ptocene (05MY) Hotocens Earth's Dynamic Systems, River, NJ. have would the observed time the the which magnetization

306 Miocene (5-23 MY) Otgocene (23-5 MY) Eocene (35-56 MY) 9.21 Upper Saddle to at
FIGURE
From