Various mechanisms to induce present-day shallow flat subduction and implications for the younger Earth: a numerical parameter study

被引:171
作者
van Hunen, J [1 ]
van den Berg, AP
Vlaar, NJ
机构
[1] ETH Honggerberg, Inst Geophys, HPP, CH-8093 Zurich, Switzerland
[2] Univ Utrecht, Inst Earth Sci, Dept Theoret Geophys, NL-3508 TA Utrecht, Netherlands
关键词
shallow flat subduction; plume-generated oceanic plateau;
D O I
10.1016/j.pepi.2003.07.027
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
Shallow flat subduction is a relatively common feature at present-day subduction zones. Several mechanisms to explain this feature have been proposed, and can be subdivided into three groups: overthrusting of the subducting plate, subduction of a plume-generated oceanic plateau, and slab suction forces. We developed a numerical model to investigate these mechanisms and tested it through a comparison of the model results with the observations of the Peru flat slab where all three mechanisms seem to be contributing. The ratio of contributions of overthrusting continent to plateau subduction is in the range of 1:1 to 1:2, and the role of plate suction forces is likely to be significant. By applying the overthrusting continent and plateau subduction mechanisms separately, we were able to determine the most important model parameters for each of the mechanisms. Overthrusting easily results in flat subduction, and the flat slab length is primarily a function of slab age, overriding plate motion and mantle viscosity. An oceanic plateau is much less likely to cause flat subduction, and favorable conditions for flat subduction include a young slab age, long-lived plateau buoyancy after subduction, a strong mantle, and addition of slab suction forces that are large enough to further reduce the subduction dip angle, once the plateau initiates this flattening. Furthermore, we found that even though today flat subduction can be explained with the dominant model parameters within a reasonable range, for a slightly hotter, younger Earth, these flat subduction conditions are much less favorable, and so this style of subduction was probably not present in the past. This contradicts earlier predictions that flat subduction was a more wide-spread phenomenon in the early stages of plate tectonics in a younger earth. (C) 2004 Elsevier B.V. All rights reserved.
引用
收藏
页码:179 / 194
页数:16
相关论文
共 63 条
[1]  
ABBOTT D, 1994, GEOLOGY, V22, P937, DOI 10.1130/0091-7613(1994)022<0937:FTSTIS>2.3.CO
[2]  
2
[3]   GABBRO-ECLOGITE REACTION-RATE AND ITS GEOPHYSICAL SIGNIFICANCE [J].
AHRENS, TJ ;
SCHUBERT, G .
REVIEWS OF GEOPHYSICS, 1975, 13 (02) :383-400
[4]  
AUSTRHEIM H, 1998, CONTINENTS COLLIDE G, P297
[6]   A low viscosity wedge in subduction zones [J].
Billen, MI ;
Gurnis, M .
EARTH AND PLANETARY SCIENCE LETTERS, 2001, 193 (1-2) :227-236
[7]   FORMATION OF THE ROCKY MOUNTAINS, WESTERN UNITED-STATES - A CONTINUUM COMPUTER-MODEL [J].
BIRD, P .
SCIENCE, 1988, 239 (4847) :1501-1507
[8]   Kinematic history of the Laramide orogeny in latitudes 35°-49°N, western United States [J].
Bird, P .
TECTONICS, 1998, 17 (05) :780-801
[9]  
Birdsall C. K., 1991, PLASMA PHYS VIA COMP
[10]   Frictional-viscous flow of phyllosilicate-bearing fault rock: Microphysical model and implications for crustal strength profiles [J].
Bos, B ;
Spiers, CJ .
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, 2002, 107 (B2)