Technology news and Jobs 
Science Early Earth buried under global ocean of lava
Science Early Earth buried under global ocean of lava | Early Earth buried under global ocean of lava |
|
| Science - Climate | |
| by William Atkins | |
| Saturday, 29 November 2008 | |
|
Page 3 of 3 Davies stated within his paper, “Subducted oceanic crust is buoyant between depths of 660 km [kilometers] and about 750 km, and this causes early episodes of layering and breakdown in numerical models of the dynamical evolution of the mantle from 4.5 Ga [geologic age] ago until the present.” Featured Whitepaper
5 Best Practices for Smartphone Support
Science DiscussionsHis abstract continues,“The layering breaks down roughly every 100–150 Ma [million years], at which time hot, fertile lower mantle floods the upper mantle and there is a dramatic burst of magmatism lasting a few million years and manifest in the models as oceanic crustal thicknesses of tens of kilometers.” “As radioactive heating declines and the mantle gradually cools, subducted plates eventually become thick and heavy enough to penetrate and disrupt the ‘basalt barrier’, and no further layering occurs after 1.6–1.8 Ga in the models." "The models yield mean residence times of mantle material (between passages through melting zones) consistent with the mantle lead-isotopic apparent age of about 1.8 Ga.” “Accumulations of (denser) basaltic material at the base of the models preserve a remarkably clear record of the early magmatic pulses." And, in conclusion, These accumulations persist strongly into the present, probably because of high internal temperature and consequent low viscosity, even though they are unlikely to form under present conditions.” |
|
Tags
| < Next story in category | Previous story in the category > |
|---|
