The effect of depth‐dependent viscosity on convective mixing in the mantle and the possible survival of primitive mantle
作者:
Michael Gurnis,
Geoffrey F. Davies,
期刊:
Geophysical Research Letters
(WILEY Available online 1986)
卷期:
Volume 13,
issue 6
页码: 541-544
ISSN:0094-8276
年代: 1986
DOI:10.1029/GL013i006p00541
数据来源: WILEY
摘要:
The effect depth‐dependent viscosity has on convective mixing and sampling (or degassing) of primitive mantle beneath ridges is explored in two‐dimensional models. Higher relative viscosities in the deep mantle decrease convection velocities and strain rates and prolong the residence time of material in the deep mantle. If the average viscosity of the lower mantle is at least 100 times the viscosity of the upper mantle, then some mantle material could have survived from very early in the earth's history. If, in addition, the depth of degassing under ridges has been less than 75 km, on average over earth history, then helium isotopic systematics are qualitatively consistent with whole mantle convect
点击下载:
PDF
(360KB)
返 回