Along the northwesterly coast of North America , a curling crack in Earth ’s crust tells the story of cataclysmal tectonic natural process that ripped through the neighborhood millions of years ago . Due to this massive shake - up , geological features that were once shape together in the same zona are now separate by some 997 kilometers ( 620 miles ) .
The split - up occurred along the Denali Fault , a 2,011 - kilometre ( 1,250 - mile ) foresighted fault that carves along the southerly crest of the Alaska Peninsula , across the bottom of the Department of State , and down into the southwestern Yukon Territory of Canada .
In a novel survey , geoscientists at the University of Alaska Fairbanks took a tight facial expression at features along the fault and find evidence that three land site – the Clearwater Mountains in Southcentral Alaska , Kluane Lake in Yukon , and the Coast Mountains near Juneau – were once part of a unified geologic feature .
Researchers had previously think over whether the three location formed individually , but the new research concluded they were once all part of a zone form during the final clashing ofland masses that formed North America .
This formation most in all probability occur when the Wrangellia Composite Terrane , an pelagic collection plate , step by step stitched into the western edge of North America between 72 million and 56 million years ago .
A1993 paperhad antecedently advert to this idea , but this latest movement set more evidence in its favor by analyzing samples of monazite – a mineral containing the rare earth elements lanthanum , cerium , neodymium , and sometimes yttrium – from the site .
The geology at those three sites showed exculpated evidence of turn back metamorphism , a topsy - turvy geological phenomenon where rocks formed under higher temperatures and pressure are found superimposed rocks formed under lower temperatures and pressures ( typically , you ’d require to find the opposite ) .
“ We evidence that each of these three independent inverted metamorphic belts all formed at the same time under similar condition . And all occupy a very similar geomorphological mount . Not only are they the same eld , they all behaved in a like way . They decrease in years , structurally , downward , ” Sean Regan , lead study generator and associate professor at the University of Alaska Fairbanks Geophysical Institute , said in astatement .
“ Our understanding of lithospheric ontogenesis , or home base growth , along the western margin in North America is becoming clear , and a big part of that is related to reconstruction of strike - slip faults such as the Denali Fault . We ’re starting to distinguish those primary features involve in the stitching , or the suturing , of once - distant country mountain to the North American plate , ” added Regan .
The new study is publish in the journalGeology .
