One of the most of import measuring tools of geology might be frequently misread , scientists at Queensland University of Technology , Australia have argued , and the effect could be serious . If we are stupefy the age of geologic features wrong , we might not just be misunderstanding the story of life on Earth , but twist our estimate of risk for volcanic eruption .
Zircons are usually modest silicate crystal common in granites . They have a duo of distinctive feature that make them big for launch the dates of rock . They eject lead when forming , but include radioactive element that slowly decay to lead with metre , providing an indication of how long this decay process has been extend . They are so tough that some have survived 4 billion years .
However , Dr Scott Bryan thinks we are take a leak a mistake in jumping from the years of zirconium silicate to the geezerhood of the rocks they contain . InEarth - Science Reviews , Bryan presents evidence that zirconium silicate from location as diverse as Queensland , New Zealand , and Hawaii , have inspire misreadings , and suggests how geologists can do better .
“ One of the effrontery being made is that the composition of the zircons and the rocks in which they have formed give an accurate record of the magmas and conditions at which the zircon and magmas formed , ” Bryan say in astatement . “ From this , we then estimate the old age of the event that caused them to form . "
" But some zircon crystals may not be related to their host rock-and-roll at all , " he added . " They may have come from the seed of the magma deep in the Earth ’s crust or they may have been picked up by the magma on its fashion to the surface . ”
When pre - existing zircons are treated as being the same age as the rocks that hold them , the antiquity of eruptions is overestimated , sometimes by million of yr .
This may sound as though have exact ages for rocks is unimaginable , but Bryan disagrees . Instead , he discusses technique to distinguish between zircon that form with rock and pre - existing crystals incorporated during an eruption . alas , these do n’t work in every causa , with uranium and thorium - rich zircons being insubordinate to such differentiation .
Problematic as inaccurate dates can be – for exercise when figure species ' ages from volcanic rocks sandwiching fossil specimens – there are crowing dangers .
Recent rumblingsin the supervolcano beneath Yellowstone National Park reminded the world of the danger such events place . But to know how likely a civilization - threatening volcanic eruption is , it is significant to know how frequently , and at what time interval , such events have fall out in the past tense . For that we usually rely on zircons , using the assumptions Bryan and his co - source knock .
