EFFECTS OF WATER-DEPENDENT CREEP RATE ON THE VOLATILE EXCHANGE BETWEEN MANTLE AND SURFACE RESERVOIRS

被引:30
作者
FRANCK, S
BOUNAMA, C
机构
[1] Universität Potsdam, D-14416 Potsdam, Projektgruppe 'Allgemeine Geophysik'
关键词
D O I
10.1016/0031-9201(95)03061-Z
中图分类号
P3 [地球物理学]; P59 [地球化学];
学科分类号
0708 ; 070902 ;
摘要
A parameterized model of mantle convection, including the volatile exchange between mantle and surface reservoirs, is used to study the thermal history of the Earth. The influence of dissolved volatiles on mantle rheology is reformulated. The weakening of mantle materials is described by a functional relationship between creep rate and water fugacity. We use flow law parameters of diffusion creep in olivine under dry and wet conditions. The mantle degassing rate is considered as directly proportional to the seafloor spreading rate, which, in turn, is dependent on the mantle heat flow. To calculate the spreading rate, we assume that the heat flow under the mid-ocean ridges is double the average mantle heat flow. The rate of regassing also depends on the seafloor spreading rate, as well as on other factors such as the efficiency of volatile recycling through island are volcanism. Both mechanisms (degassing and regassing) are coupled self-consistently with the help of a parameterized convection model under implementation of a different formulation of mantle viscosity. The model is run for 4.6 Gyr. Time series of average mantle temperature, volatile loss, mantle viscosity, mantle heat flow, Rayleigh number and Urey ratio are calculated. The effects of changing initial parameters have been tested and found negligible for the final results. Mantle water is outgassed rapidly within a time scale of less than 200 Myr for all numerical simulations. The present-day values of calculated parameters are in the generally accepted range.
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页码:57 / 65
页数:9
相关论文
共 23 条
[1]   SUBSTANTIAL HYDROGEN SOLUBILITY IN OLIVINE AND IMPLICATIONS FOR WATER STORAGE IN THE MANTLE [J].
BAI, Q ;
KOHLSTEDT, DL .
NATURE, 1992, 357 (6380) :672-674
[2]   THERMAL EVOLUTION MODELS FOR THE EARTH [J].
CHRISTENSEN, UR .
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH AND PLANETS, 1985, 90 (NB4) :2995-3007
[3]  
Franck S., 1988, Gerlands Beitraege zur Geophysik, V97, P119
[4]   ON THE SENSITIVITY OF PARAMETERIZED CONVECTION TO THE RATE OF DECAY OF INTERNAL HEAT-SOURCES [J].
JACKSON, MJ ;
POLLACK, HN .
JOURNAL OF GEOPHYSICAL RESEARCH, 1984, 89 (NB12) :103-108
[5]   DIFFUSION CREEP IN PEROVSKITE - IMPLICATIONS FOR THE RHEOLOGY OF THE LOWER MANTLE [J].
KARATO, S ;
LI, P .
SCIENCE, 1992, 255 (5049) :1238-1240
[6]   RHEOLOGY OF THE UPPER MANTLE - A SYNTHESIS [J].
KARATO, S ;
WU, P .
SCIENCE, 1993, 260 (5109) :771-778
[7]   PLASTICITY OF MGSIO3 PEROVSKITE - THE RESULTS OF MICROHARDNESS TESTS ON SINGLE-CRYSTALS [J].
KARATO, S ;
FUJINO, K ;
ITO, E .
GEOPHYSICAL RESEARCH LETTERS, 1990, 17 (01) :13-16
[8]  
KARATO S, 1989, RHEOLOGY SOLIDS EART, P176
[9]  
KARATO S, 1995, IN PRESS SCIENCE
[10]   RHEOLOGY OF SYNTHETIC OLIVINE AGGREGATES - INFLUENCE OF GRAIN-SIZE AND WATER [J].
KARATO, SI ;
PATERSON, MS ;
FITZ GERALD, JD .
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH AND PLANETS, 1986, 91 (B8) :8151-8176