期刊
GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS
卷 17, 期 10, 页码 4105-4127出版社
AMER GEOPHYSICAL UNION
DOI: 10.1002/2016GC006527
关键词
-
资金
- department of Earth Science and Engineering, Imperial College London
- VoiLA project (NERC) [NE/K010743/1]
- NERC [NE/I024429/1]
- NSF [OCE-1358091]
- ARC [FT140101262]
- Natural Environment Research Council [NE/I024429/1, NE/K010743/1, NE/I024488/1] Funding Source: researchfish
- NERC [NE/I024429/1, NE/I024488/1, NE/K010743/1] Funding Source: UKRI
Subduction zone mantle wedge temperatures impact plate interaction, melt generation, and chemical recycling. However, it has been challenging to reconcile geophysical and geochemical constraints on wedge thermal structure. Here we chemically determine the equilibration pressures and temperatures of primitive arc lavas from worldwide intraoceanic subduction zones and compare them to kinematically driven thermal wedge models. We find that equilibration pressures are typically located in the lithosphere, starting just below the Moho, and spanning a wide depth range of similar to 25 km. Equilibration temperatures are high for these depths, averaging similar to 1300 degrees C. We test for correlations with subduction parameters and find that equilibration pressures correlate with upper plate age, indicating overriding lithosphere thickness plays a role in magma equilibration. We suggest that most, if not all, thermobarometric pressure and temperature conditions reflect magmatic reequilibration at a mechanical boundary, rather than reflecting the conditions of major melt generation. The magma reequilibration conditions are difficult to reconcile, to a first order, with any of the conditions predicted by our dynamic models, with the exception of subduction zones with very young, thin upper plates. For most zones, a mechanism for substantially thinning the overriding plate is required. Most likely thinning is localized below the arc, as kinematic thinning above the wedge corner would lead to a hot fore arc, incompatible with fore-arc surface heat flow and seismic properties. Localized subarc thermal erosion is consistent with seismic imaging and exhumed arc structures. Furthermore, such thermal erosion can serve as a weakness zone and affect subsequent plate evolution.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据