|
|||||
|
|
| Poisson's ratio of eclogite: Implications for lower crustal delamination of orogens | |
| 作者姓名： | 高山 Hartmut Kern 金振民 张宏飞 张本仁 |
| 作者单位： | Faculty of Earth Sciences,China University of Geosciences,Wuhan 430074,China,Department of Geology,Northwest University,Xi'n 710069,China,Institut f Geowissenschaften,Universit Kiel,Olshausenstrasse 40,24098 Kiel,Germany,Faculty of Earth Sciences,China University of Geosciences,Wuhan 430074,China,Faculty of Earth Sciences,China University of Geosciences,Wuhan 430074,China,Faculty of Earth Sciences,China University of Geosciences,Wuhan 430074,China |
| 基金项目： | 国家自然科学基金,科技部资助项目 |
| 摘 要： | Eclogite is essentially a bi-mineralogic high-grade metamorphic rock consisting of garnet and omphacite and is the product of high-to-ultrahigh pressure metamorphism of basaltic rocks due to the subduction of oceanic crust or the thickening/subduction of … |
| 关 键 词： | eclogite Poisson抯 ratio orogen delamination of lower crust. |
Poisson’s ratio of eclogite: Implications for lower crustal delamination of orogens |
|
| Shan?Gao | |
| Authors: | |
| Institution: | 1. Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074, China;Department of Geology, Northwest University, Xi'an 710069, China 2. Institut für Geowissenschaften, Universitat Kiel, Olshausenstrasse 40, 24098 Kiel, Germany 3. Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074, China |
| Abstract: | Laboratory measurements of combined P- and S-wave-velocities of eclogite from the Dabie-Sulu ultrahigh pressure metamorphic belt and from literature data show a significant increase of Poisson's ratio of eclogite with its intrinsic water content H2O+ and thus the degree of hydration. Unaltered eclogites with H2O+<1.0% have an average Poisson's ratio between 0.24 and 0.25, which is identical to that calculated from single crystal elastic properties but lower than the averages (0.27±0.02) of measurements compiled by previous studies. Thus, the Poisson's ratio of unaltered eclogites is considerably lower than that of lower crustal mafic granulite and upper mantle peridotite. The lower crust and upper mantle of the Dabie ultrahigh pressure metamorphic belt, the northern and southern parts of the Tibetan Plateau as well as the central Andes, where eclogite may have formed during Mesozoic and Cenozoic tectonism, are characterized by the Poisson's ratio >0.26. This, together with their normal upper mantle P-wave velocities, implies that eclogites are no longer an important component of the present-day lower crust and upper mantle of these subduction-collision belts. Combined with age constraints on eclogite-facies metamor- phism and subsequent exhumation, this in turn suggests that the interval from formation to delamination of eclogites is confined to a very short period of <15 Ma. |
| Keywords: | eclogite Poisson's ratio orogen delamination of lower crust |
| 本文献已被 CNKI 万方数据 SpringerLink 等数据库收录！ | |