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Guest Blog: Hermann Burchard on Siberian Hot Spot Tracks
event February 12, 2010 comment 2 Comments
This note is a summary of aspects of Siberian geology as far as I have been able to gather relevant facts, occasioned in part by and meant to correct errors in what I heard on a TV program dealing with the Siberian traps [“Earth’s Deadliest Eruption,” Feb 9, History Channel, AETN, affiliated with British Sky Broadcasting, often runs programs from BBC].However, in so doing, I am suggesting new evidence, not previously published in any form, to my knowledge.

While reporting on many interesting known facts concerning geology of the eruptions, some remarks in the program appeared to be in error: Although the idea of a hotspot track was mentioned, with the Hawaiian sea mount chain given as an example, the astounding declaration was made that the Siberian eruptions ended after a million years (~249 M yrs ago) and no hotspot track for the Siberian hotspot was known, so stated explicitly.

To the contrary, I believe the hotspot track is clearly visible on Google maps satellite image (NOT Google Earth, which is a bit blurry), see below for details, eruptions continuing ever since.

The track’s total extent includes a continental and an oceanic part.  It stretches from the Siberian Basin to the Hawaiian volcanoes, so that in fact the hotspot related to the end-Permian extinction event is known, eruptions have gone on at first in the form of super-volcanoes, at least until early Cretaceous times, finally subsiding gradually to today’s Hawaiian volcanoes, as explained further below.

In Siberia proper, the hotspot track passes just N of Yakutsk and runs from NW to SE across the map, as an almost exactly straight line (testimony to the exceedingly steady plate motion over 150 M yrs of the Earth’s crust as it dragged across the hotspot in the mantle beneath).The track should stand out clearly and be visible by its discoloration on the satellite image, sometimes brighter, or darker, than the surround.Its visible aspect terminates in a promontory East of Magadan on the Sea of Okhotsk.  The NW terminus is at the Putorana Plateau, recognizable by its deeply dissected surface, with the city of Noril’sk on its Western edge.  The Siberian Basin is adjacent to the West.

From East of Magadan the track runs under the Sea of Okhotsk (buried beneath sediment) and under Kamchatka, to emerge in the Great Cusp formed by the Kuril and Aleut island chains and by the corresponding plate tectonic subduction trenches, an event reliably dated to a little over 85 M yrs ago, the age of the Detroit Seamount, Western-most for which DSDP cores could be dated.  The cusp formed by the trenches, by all appearances, is due to the hotspot track which is anchored deep in the mantle resisting subduction.  The track goes on in the Emperor-Hawaii sea mount chain.


View Larger Map

[Brief detailed map instructions:  To see the track on your browser, open maps.google.com and enter “Yakutsk” then click “search maps”.  Choose satellite view (upper right of screen).  Click the arrows (<<, upper left), to open map to full width.  Move zoom slide down until the scale on the lower left hand corner says 200 km.  The map will show maybe 3,000 km of Siberian territory from West to East.  Drag the map slightly so that the Magadan promontory with the SE terminus of the visible part of the track is in the lower right hand corner of your screen.  At the 200 km scale, the Putorana Plateau should be on the upper left corner, if not try clicking <<, or it may be necessary for you to use screen zoom features.]

Controversially, the Siberian Basin and S Kara Sea to the West are the origin of the hotspot where a giant comet hit that ended the Permian period (>100 km diameter, perhaps a Kuiper Belt object), breaking into two or more fragments due to “impact focussing”, i.e., near Earth tidal forces tearing apart the lumpy, dirty snowball that a comet is, loosely held together by internal gravity.  The double S-curve of the Urals forms a partial crater wall for the two adjacent 2,000 km diameter impact craters.The cross section of the mountain chain and numerous geological details are evidence for this fact.  The city of Perm is on the gentle West slope.(Where is the rest of the crater wall, .. perhaps in N America?)

The former Mongol-Okhotsk Ocean was reduced to the current Sea of Okhotsk in late Jurassic/ early Cretacious times when the growing hotspot track caused fusion of mainland Asia and Siberia.

The famous dinosaur beds in the Gobi desert and Liaoning province were laid down at that time, fine ash from super-volcano (caldera) eruptions of the hotspot burying and preserving amazing detail of feathered dinosaurs and early birds, when the caldera was near Yakutsk.  In that period, the region was in a subtropical location, as the hotspot has moved little over time if at all.  The giant impact likely caused the vast Pacific Ocean to open with Hawaii still near its center even today, splitting the crust.

Several papers by geologists were consulted for this summary.  While, admittedly, I do not own a geological map of Siberia, and none may be for sale in the West, the geological foundations of these various geographical features should be easily ascertainable by professional geologists.  The entire track is studded with mining treasures of all sorts, so perhaps this explains why the track is not better known until now.