Evidence of high water content in the deep upper mantle inferred from deformation microstructures
Evidence of high water content in the deep upper mantle inferred from deformation microstructures
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DOI：
10.1130/g21332.1
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发表时间：
2005-07
期刊：
影响因子：
5.8
通讯作者：
I. Katayama;S. Karato;M. Brandon
中科院分区：
文献类型：
--
作者：
I. Katayama;S. Karato;M. Brandon
来自挪威加里东山脉的深部上地幔岩石显示出在不同含水量下橄榄石和石榴石中存在大应变变形的证据。使用显微结构的观察，包括晶格择优取向的橄榄石和亚晶界的多晶石榴石，我们推断以下变形历史。当深度超过150 km时，大应变变形发生在低应力（10 MPa）和中等温度（1300 K）下，涉及高含水量（>1000 H/106 Si）的橄榄石。随后在较低的含水量（~ 200-1000 H/106 Si）和适度的应力（~ 40 MPa）下在较浅的部分中进行低应变变形。这些观测结果表明，该区域上地幔深部的含水量比洋中脊附近的上地幔高得多。
Deep upper-mantle rocks from the Norwegian Caledonides show evidence for large strain deformation in both olivine and garnet under varying water contents. Using microstructural observations, including lattice-preferred orientation of olivine and subgrain boundaries of majoritic garnet, we infer the following deformation history. At depths exceeding ∼150 km, large strain deformation occurred at low stress (∼10 MPa) and modest temperature (∼1300 K), involving high water content (>1000 H/10 6 Si in olivine). This was followed by low strain deformation at lower water content (∼200–1000 H/10 6 Si) and modest stress (∼40 MPa) in the shallower parts. These observations show that the deep upper mantle in this region had a considerably higher water content than the upper mantle near mid-ocean ridges.