| 新疆东准噶尔花岗岩类岩石高温高压弹性波速度及其对地壳结构的约束 |
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| 引用本文： | 臧春娟,王明梁,刘永刚,唐红峰.新疆东准噶尔花岗岩类岩石高温高压弹性波速度及其对地壳结构的约束[J].地球物理学报,2014,57(7):2099-2112. |
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| 作者姓名： | 臧春娟 王明梁 刘永刚 唐红峰 |
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| 作者单位： | 1. 中国科学院地球化学研究所 地球内部物质高温高压实验室, 贵阳 550002;2. 中国科学院大学, 北京 100049;3. 宿州学院 地球科学与工程学院, 安徽宿州 234000 |
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| 基金项目： | 国家自然科学基金项目(41172071);2012西部之光一般项目资助 |
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| 摘 要： | 应用超声波反射-透射法，在最高压力为1.0 GPa（室温），最高温度为700℃（1.0 GPa）的条件下对新疆东准噶尔地区的卡拉麦里花岗岩带和野马泉岩体的典型花岗岩类岩石（碱长花岗岩、碱性花岗岩、花岗闪长岩、二长花岗岩和石英闪长岩）的纵波速度（VP）和横波速度（VS）进行了测量.结果显示，在常温、压力0.4~1.0 GPa条件下，东准噶尔地区花岗岩类岩石的VP和VS均随压力呈线性增加，说明在这个压力段岩石中的微裂隙已基本闭合.室温、1.0 GPa时花岗岩类岩石的VP是5.79~6.84 km·s-1，VS是3.26~3.85 km·s-1.依据压力与VP及压力与VS的线性关系，拟合得到常温常压下花岗岩类岩石的纵波和横波压力系数分别是0.1568~0.4078 km/（s·GPa）和0.0722~0.3271 km/（s·GPa），VP0和VS0分别是5.62~6.47 km·s-1和3.15~3.75 km·s-1.恒压1.0 GPa、室温到700℃条件下，花岗岩类岩石的VP和VS均随温度的升高呈线性降低，温度系数分别为（-3.41~-4.96）×10-4 km/（s·℃）和（-0.88~-3.22）×10-4 km/（s·℃）.利用实验获得的花岗岩类岩石的VP0、VS0及温度系数和压力系数，结合东准噶尔地区的地热资料，建立了VP和VS随深度变化的剖面.将获得的VP和VS-深度剖面与该区地球物理探测结果对比，发现东准噶尔地区的碱长花岗岩、碱性花岗岩、二长花岗岩和部分花岗闪长岩的VP和VS与该区上地壳速度吻合很好，同时这几种岩石的平均泊松比也与上地壳泊松比一致，因此我们认为这几种类型的岩石是该区上地壳的重要组成部分.另外，石英闪长岩的VP和VS均符合中地壳的速度，可能为中地壳中的一种岩石.
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| 关 键 词： | 弹性波速度 高温高压实验 花岗岩类 地壳结构 新疆东准噶尔 |
| 收稿时间： | 2013-09-22 |
The elastic wave velocities of the granitoids from Eastern Junggar of Xinjiang at high temperature and high pressure and their geological constraints on the crustal structure |
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| ZANG Chun-Juan,WANG Ming-Liang,LIU Yong-Gang,TANG Hong-Feng.The elastic wave velocities of the granitoids from Eastern Junggar of Xinjiang at high temperature and high pressure and their geological constraints on the crustal structure[J].Chinese Journal of Geophysics,2014,57(7):2099-2112. |
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| Authors: | ZANG Chun-Juan WANG Ming-Liang LIU Yong-Gang TANG Hong-Feng |
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| Institution: | 1. Laboratory for High Temperature & High Pressure Study of the Earth's Interior, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China;2. University of Chinese Academy of Sciences, Beijing 100049, China;3. School of Earth Science and Engineering, Suzhou University, Anhui Suzhou 234000, China |
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| Abstract: | The compressional (VP) and shear wave velocities (VS) of typical granitoids (alkali-feldspar granite, alkaline granite, granodiorite, monzogranite and quartz diorite) from Kalamaili granite belt and Yemaquan body in Eastern Junggar, Xinjiang were experimentally measured at pressures up to 1.0 GPa (room temperature) and temperatures up to 700℃ (1.0 GPa) by ultrasonic reflection-transmission method. The results show that both VP and VS of the granitoids present a linear velocity increase with the pressure at room temperature from 0.4~1.0 GPa, which is interpreted in terms of closure of the microcracks in rocks under this pressure range. The VP and VS of the granitoids are 5.79~6.84 km·s-1 and 3.26~3.85 km·s-1 respectively at room temperature and 1.0 GPa. On the basis of the linear relationship between pressure with VP and VS, we derived the pressure derivatives of VP and VS as 0.1568~0.4078 km/(s·GPa) and 0.0722~0.3271 km/(s·GPa) respectively, and the reference velocities VP0and VS0 are 5.62~6.47 km·s-1 and 3.15~3.75 km·s-1 respectively. At 1.0 GPa, VP and VS of the granitoids show a linear decrease with temperature from room temperature to 700℃, and temperature derivatives of velocities are (-3.41~-4.96)×10-4 km/(s·℃) and (-0.88~-3.22)×10-4 km/(s·℃), respectively. Taking advantage of derivatives of velocities and reference velocities of the granitoids obtained from our experiments, and combining regional geothermal resources of East Junggar area, VP and VS-depth profiles were calculated. From the comparison of velocity-depth profiles with geophysical exploring results, we infer that the VP and VS of the alkali-feldspar granite, alkaline granite, monzogranite and part of granodiorite in Eastern Junggar of Xinjiang are coherent well with the velocity of the upper crust, and the average Poisson's ratio of several rocks are also consistent with the Poisson's ratio of the upper crust. Therefore, we suggest that these kinds of rocks are important parts of the upper crust in this region. In addition, the VP and VS of the quartz diorite are both in accord with the middle crust, suggesting that it may be one kind of rocks in the middle crust of this region. |
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| Keywords: | Elastic wave velocity High temperature and high pressure experiment Granitoids Crustal structure Eastern Junggar of Xinjiang |
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