Скачать или смотреть Paleomagnetic observations of motion Plates, hotspots and the entire solid Earth

Dr. John Tarduno (University of Rochester) gave a guest lecture via Skype in Fall 2008 for a graduate class on Advanced Plate Tectonics in SOEST, University of Hawaii at Manoa. The students recorded the lecture and produced video podcasts of the event. This is one of 8 such lectures from the course which was taught by Prof. Paul Wessel.

ABSTRACT:

"Paleomagnetic data are the basis for many of the observations of past plate, mantle and solid Earth motions that are used to understand geodynamic processes. Here I review the use of paleomagnetic data with a topical approach, focusing on tests of past Hawaiian hotspot motion. I will pause this discussion to include a few brief tutorials that explain: 1. why we know the past geometry of the magnetic field 2. the differences between paleomagnetic data and model poles from remote sensing and 3. the definition of polar wander. The Hawaiian--Emperor hotspot chain, and its distinctive bend at 47 Ma, have figured prominently in the development of ideas concerning the nature of mantle plumes, plate motion, and frames of reference. However, paleomagnetic data from Ocean Drilling Program (ODP) Leg 197 (Tarduno et al., 2003), together with results from plate circuit (e.g. Cande et al., 1995) and geodynamic modeling studies (e.g. Steinberger and O'Connell, 1998), indicate southward motion of the Hawaiian hotspot during formation of the Emperor Seamounts. These analyses confirm the idea that mantle plumes should be influenced by mantle flow and that such motion must be considered when constructing frames of reference for plate motion. An important corollary of this finding on hotspot motion is that long-term polar wander of Earth has been inaccurately assessed by viewing paleomagnetic data in a fixed hotspot reference frame (tutorial #3). The Pacific paleomagnetic data can also be used for consistency tests of plate circuit models (Doubrovine and Tarduno, 2008). Results from the latter analysis allow us to reconstruct a hypothetical track for the Hawaiian hotspot had it actually been nearly fixed in the deep mantle during Late Cretaceous to Paleogene times (Tarduno, 2007). This is a useful starting point for understanding the relative roles that plate and mantle processes play in shaping hotspot tracks."

(References: Cande et al., Science, 270, 947-953, 1995; Doubrovine and Tarduno, B07104, JGR, 2008; Steinberger and O'Connell, GJI, 132, 412-434, 1998; Tarduno et al., Science, 301, 1064-1069, 2003; Tarduno, Chem. Geol., 241, 234-247, 2007.)