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Supervolcanoes in the Mid-Pacific Mountains? Pat Wilde Pangloss Foundation Berkeley, Ca 94702 [email protected] http://marscigrp.org/agu2010.ppt Sea floor physiographic reconstructions from satellite gravity show crater like features in the Mid-Pacific Mountains of the Central Pacific Ocean. These features are not seen on conventional bathymetric charts in the area due to sparse trackline information. Up to seven huge craters, treading in a southeast northwest direction are seen, some several hundred miles in diameter. Some craters are nested and the area looks similar to the lunar surface. The water depth is in excess of 5000 meters. Water depth makes progressive impacts unlikely. A possible analog is an oceanic supervolcanic belt, like Yellowstone. The craters decrease in size from the southwest, suggesting waning hot spot activity to the northwest with time. The intermediate composition of some of rocks from the surveyed seamounts suggest the result of hot spot activity may be different from usual linear seamount formation on typical oceanic crust. Some seamounts that rim the craters in the north are dated to about 90 Myrs and the sea floor in the region is one of the oldest known at 180 Myrs. Thus the age of the formation is Jurassic into the Cretaceous. The rate of progression and the timing can not be determined at this time as there are very few dated seamounts that rim the craters. Google Ocean view Google view ‘lighten’ WHAT ARE THEY? Lunar like (craters) features in the Mid-Pacific at 5000+ meters depth and ca. 100 Myr old? • IMPACT CRATERS? • EXPLOSION CRATERS? • PATTERN RECOGNITION ARTIFACTS? Solid circles realistic craters Dotted ‘optimistic’ Magnetics Gravity Tectonic situation-Pacific Plate stretched MID-PACIFIC MOUNTAINS IMPACT CRATERS? -Impact translated through 6000 m seawater? -Increasingly larger boloids arriving in linear trend over million of yrs in same area? -No evidence of faunal/flora change or tsunami deposits at crater creation time. Impact origin seems unlikely Crater stats from Impact Model crater size vs impacts Univ. Ariz Model <http://www.lpl.arizona.edu/tekton/crater.html> dia. Km Dia. meters Energy Pi value Pi Scale Joules Megatons Form time secs A B C D E Solid boloid hitting rock target 360 1.87 x 10^4 1.48 x 10^24 225 1.12 x 10^4 0.32 x 10^24 125 5.92 x 10^3 4.71 x 10^22 100 4.65 x 10^3 2.28 x 10^22 72 3.25 x 10^3 0.78 x 10^22 3.54 x 10^8 7.65 x 10^7 1.13 x 10^7 5.44 x 10^6 1.86 x 10^6 5.87 x 10^1 4.81 x 10^1 3.75 x 10^1 3.41 x 10^1 2.97 x 10^1 A B C D E Icy boloid hitting rock target 360 2.99 x 10^4 2.02 x 10^24 225 1.79 x 10^4 4.36 x 10^23 125 9.47 x 10^3 5.42 x 10^22 100 7.43 x 10^3 0.31 x 10^23 72 0.52 x 10^4 1.06 x 10^22 4.82 x 10^8 1.04 x 10^8 1.53 x 10^7 4.71 x 10^6 2.54 x 10^6 7.05 x 10^1 5.78 x 10^1 4.51 x 10^1 0.41x 10^2 3.57 x 10^1 From Madder and Giddings (2002) From Mader and Giddings (2002) EXPLOSION CRATERS? • Linear trend analogous to Yellowstone supervolcanoes and precursors • 5000 m plus depth would mask any surface expression of formation as no evidence at that time of flora/fauna change or tsunami deposits Formation over hot spot with migrating Pacific Plate likely cause YELLOWSTONE SUPERVOLCANO SUPERVOLCANO TREND Similar Features? • Shatsky Rise: potential supervolcano field as proposed by Sager but no crater field • Shiva Crater (questionable) Other reported crater- Shiva Shiva Gravity- unlikely crater Which way? Trend from overlapping crater rims is a. Northwest to Southeast compatible with plate motion over hot spot b. Increase in crater size in that direction c. Potential parallel crater formation to southwest of most obvious trend?? CRATER FORMATION SEQUENCE • During K, Pacific Plate stretched and moved North. Thus craters above hot spot younger to the South. • Supervolcano explosions apparently larger with time. Why oceanic craters so rare? • Most hot spot sea mounts obviously on oceanic crust. Lack of internal water makes single volcano more likely than explosion during eruption. Could it be Mid-Pacific mountains remnant continental crust area in Cretaceous moving over hot spot, which would provide water? THE LOST CONTINENT OF MU! Could it be??!!