What caused the bend in the Emperor/Hawaii chain of islands, 45 million years ago?
Has there been any updates to this mystery I am unaware of? Are there any new theories that could potentially explain it?
There is a lot of material but no answer at the link provided. University of Hawaii material discussing the root cause of the pattern of formation of the Emperor and Hawaii chain of islands
Perhaps it is even more amazing that in the past 65 million years there has been only one such bend. Even more remarkable is the observation that the straight portions of the chain are straight. As we shall see below, the configuration of the plate boundaries in the Pacific have changed dramatically during the lifetime of the Hawaiian hotspot. If, as many geophysicists believe, subduction drives tectonics, then how on earth can the straight parts be so straight and move at constant velocities for tens of millions of years? The answer to these questions remains a mystery!
ADDED: Sept 1st. an excerpt from a link to information in the comment below. thank you MyCarta, good information:
The bend in the Hawaiian-Emperor seamount chain is a prominent feature usually attributed to a change in Pacific plate motion approx 47 Myr ago. However, global plate motion reconstructions fail to predict the bend. Here we show how the geometry of the Hawaiian-Emperor chain and other hotspot tracks can be explained when we combine global plate motions with intraplate deformation and movement of hotspot plumes through distortion by global mantle flow. Global mantle flow models predict a southward motion of the Hawaiian hotspot. This, in combination with a plate motion reconstruction connecting Pacific and African plates through Antarctica, predicts the Hawaiian track correctly since the date of the bend, but predicts the chain to be too far west before it. But if a reconstruction through Australia and Lord Howe rise is used instead, the track is predicted correctly back to 65 Myr ago, including the bend. The difference between the two predictions indicates the effect of intraplate deformation not yet recognized or else not recorded on the ocean floor. The remaining misfit before 65 Myr ago can be attributed to additional intraplate deformation of similar magnitude.
I don't know if that is definitive or not?
I have come across this image showing the lately determined "pattern of expansion" the earth is undergoing: perhaps then the quote above is indicating a "perceived balance caused in the expansion as correctly predicting and matching the movement of the plume and plates relative to the pattern?
****UPDATE Sept 24th -- Information from MyCarta**
MyCarta "I think the more recent research leans towards a combination of intraplate deformation and movement of the plume itself, combined with the plate motion, e.g."
And about Euler plates, and Lord Howe's Rise
as added in a comment below, quoted from the paper's abstract:
if a reconstruction through Australia and Lord Howe rise is used instead, the track is predicted correctly back to 65 Myr ago, including the bend.
From the first paragraph in the paper:
Hotspots are frequently assumed to be fixed and used as a reference frame for plate motions. However, when the Hawaiian hotspot track is predicted from a global plate motion chain based on relative plate motion data, and it is assumed that the Hawaiian hotspot is fixed relative to African hotspots, it does not fit the observed track: the predicted track is essentially straight, lies south of the Hawaiian seamount chain, and has no feature corresponding to the Hawaiian-Emperor bend. Explanation of this misfit requires one of the following, or a combination of them, to be true: (1) motion of Pacific plate hotspots, in particular more than 1,000 km south-westward motion for the Hawaiian hotspot between ,80 Myr ago and the time of the bend and minor southward motion after this time, (2) motion of hotspots in the African hemisphere, (3) motion at an additional plate boundary, or (4) deformation at a diffuse intraplate boundary not included in the plate motion chain. Palaeomagnetic data from the Emperor chain3 yield a southward component of Hawaiian hotspot motion more than 1,000 km relative to the palaeomagnetic axis between ,80 and 49 Myr ago.
In the rest of the paper they used 2 main models (other models were discarded). The first included only hotspot motion which is sufficient to explain discrepancies between predicted and observed hotspot tracks (e.g. Hawaiian-Emperor chain) back to 47 Ma ago, but before 47 Ma ago the predicted hotspot tracks do not include the bend. Their second model added intraplate deformation (in their reference plates Antarctica/New Zealand) to hotspot motion and is able to predict the hotspot track all the way back to 65 Ma ago with good accuracy, including the bend, and with less accuracy (meaning that it is off too far to the west) until 85 My ago."
Sept 24th MORE QUESTION
I'm getting the feeling tectonic plate heave and settle and patterns of interaction are the current best theory for the resulting relative motion of the Hawaii hotspot.
So we are increasing the scale of the question to ask what is it that drives the schedule of the tectonic plates, such that the result is the ever so slow motion of the Hawaii hotspot. What is felt to be the root cause of timing of plate and continent shift??