Dating in Hawaii

?I thought that the cause was simple plate movement with respect to the magma plume; i.e. that the plates moved over the hotspot, not that the hotspot moved under the plates.I seem to recall a correlation between palaeomagnetic data indicating the position of magnetic north and its movement over time, and the position of the volcanoes produced by the plume.I'll try to dig it up.The Rockhound

Hey Irish,Yes, the mantle plume/hot spot theory was the original and much favored theory for a long time. However, recently the entire mantle plume theory has been called into question.I don't have time to get into much detail at the moment as I'm leaving for home in a bit, but try this site for a good discussion: Mantle PlumesThis message has been edited by roxrkool, 01-10-2005 18:21 AM

indeed it does happen. I know I have done it, and fairly recently too. had to look up guyot, and now am more confused ...one source says "A flat-topped submarine mountain" and another says "a seamount of volcanic origin (especially in the Pacific Ocean)"now it is possible to be both of these or either one and not the other ...

---

we are limited in our ability to understand
by our ability to understand RebelAAmerican.Zen[Deist
{{{Buddha walks off laughing with joy}}}

I think that they are mostly both. I can't say I know that there aren't any of non volcanic origin though

quote:

---

had to look up guyot, and now am more confused ...

​

one source says "A flat-topped submarine mountain" and another says "a seamount of volcanic origin (especially in the Pacific Ocean)"

​

now it is possible to be both of these or either one and not the other ...

---

--It is my understanding that they are essentially both. These undersea 'mountains' are built by hot spot volcanism like that seen in Hawaii. Over time as the island moves away from the center of hot spot volcanism (or the corresponding mantle plume moves away from the island [or even both]), it is eroded and gradually subsides as the oceanic lithosphere on which it stands ages and thickens. The problem with young seafloor timescales such as that implied by CPT is indicative from an analysis of the summit geomorphology of a typical guyot. Summit geomorphology of a typical guyot consists of flat topped Layered lagoonal facies upon a volcanic basment with reef facies 'encrested' around the layered lagoonal facies. And for older guyots there is also a pelagic sediment cover superposing the lagoonal facies.While you may not necessarily understand the literature, I suggest finding a copy of AGU's geophysical monograph #77. There are 5 papers therein which go into excrutiating detail explaining the geology and geophysics of Western Pacific guyots. And what may be more interesting to you, pretty pictures and detailed schematic interpretations of seismic reflection data.See: Pringle, Sager, Sliter, Stein; The Mesozoic Pacific: Geology, Tectonics, and Volcanism, Geophysical Monograph 77. 1993This message has been edited by TrueCreation, 01-11-2005 01:04 AM

The oceanic seafloor also cools, becoming more dense, as you move away from the ridges. This is another reason why they subside.

quote:

---

... which go into excrutiating detail...

---

lol Definitely read some of those papers. I take it you're not going to study geology?

lol Definitely read some of those papers. I take it you're not going to study geology?[/quote] --ok.. excrutiating relative to what RAZD may otherwise have access to or read..

thanks. I also went to wikipedia, which pretty much says it is both.Guyot - Wikipedia and
Hawaiian—Emperor seamount chain - Wikipediawhich lead me to external link
Hawaii Center for Volcanology | Formation of the Hawaiian Islandswhich has the graph in the OP.ps - my 'confusion' was a little tongue in cheek and concerned more with the disagreement in the definitions than in the concepts.This message has been edited by RAZD, 01-11-2005 21:10 AM

---

we are limited in our ability to understand
by our ability to understand RebelAAmerican.Zen[Deist
{{{Buddha walks off laughing with joy}}}