ELASTIC WAVE VELOCITY OF ROCKS AT HIGH PRESSURE AND TEMPERATURE AND PETROLOGICAL MODEL OF CRUSTAL STRUCTURES

高温高压下岩石弹性波速与地壳结构岩石模型

基本信息

批准号：
12440147
负责人：
ARIMA Makoto
金额：
$ 6.91万
依托单位：
YOKOHAMA NATIONAL UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

项目摘要

In order to better constrain the interpretation of the seismic structures, experimental measurements at high pressure (up to 1000 Mpa) and temperature (up to 1000□) of the compressional wave velocity (Vp) and shear wave velocity (Vs) on rock samples representative of deep crustal lithologies from the Mount Tanzawa (central Japan), Ichinomegata (NE Japan), Kohistan paleo-crustal section (northern Pakistan), Lutzow-Holm Bay and Enderby Land (East Antarctica) have been performed.The main results are :(1) Vp of the garnet clinopyroxenite decreases linearly from room temperature to 800 ℃, and decreases rapidly at temperatures higher than 800 ℃. Vp of the dunite decreases linearly from room temperature to 1000 ℃. Vp of the garnet clinopyroxenite is 7.74 km/s at room temperature, 7.70 km/s at 400 ℃, 7.66 km/s at 700 ℃, and 7.45 km/s at 1000 ℃. Vp of the dunite is 8.49 km/s at room temperature, 8.30 km/s at 400 ℃, 8.12 km/s at 700 ℃, and 7.90 km/s at 1000 ℃. Temperature derivative of Vp is-1.24 10-4 km/s℃ for the garnet clinopyroxenite and -6.06 10-4 km/s℃ for the dunite.(2) At constant pressure of 1.0 Gpa, the Vp of hornblende gabbro gradually decreased from 7.21 km/s at 25 ℃ to 6.91 km/s at 700 ℃. Similarly the Vp values of the pyroxene-hornblende gabbros reduces from 7.06 km/s at 25 ℃ to 6.73 km/s 800 ℃. Also the Vp value of the hornblendite lowers from 7.11 km/s (25 ℃) to 6.45 km/s (800 ℃).

为了更好地约束地震结构的解释，在高压（高达1000 Mpa）和温度（高达1000□）下对代表性岩石样品的压缩波速（Vp）和剪切波速（Vs）进行实验测量丹泽山（日本中部）、Ichinomegata（日本东北部）、Kohistan 古地壳部分（巴基斯坦北部）的深层地壳岩性，在Lutzow-Holm Bay和Enderby Land（南极洲东部）进行了实验。主要结果是：（1）石榴石单斜辉石岩的Vp从室温到800℃呈线性下降，并且在温度高于800℃时迅速线性下降。从室温到 1000 ℃，石榴石斜辉石的 Vp 为室温下为7.74 km/s，400 ℃下为7.70 km/s，700 ℃下为7.66 km/s，1000 ℃下为7.45 km/s，纯橄榄岩的Vp在室温下为8.49 km/s，8.30 km/s。 400℃时为8.12公里/秒，700℃时为8.12公里/秒， 1000 ℃时，Vp 的温度导数为-1.24 10-4 km/s℃，石榴石斜辉石为-6.06 10-4 km/s℃。 (2) 在 1.0 Gpa 的恒定压力下，角闪辉长岩的Vp从25 ℃时的7.21 km/s逐渐下降到同样，700 ℃时辉石角闪石辉长岩的 Vp 值从 25 ℃ 时的 7.06 km/s 降低到 800 ℃ 时的 6.73 km/s。 (25℃)至6.45公里/秒(800℃)。