白一鸣^1,2,,
艾印双^1,2,3,,,
姜明明^1,3,
何玉梅^1,3,
陈棋福^1,2
1. 中国科学院地质与地球物理研究所, 地球与行星物理重点实验室, 北京 100029
2. 中国科学院大学地球科学学院, 北京 100049
3. 青藏高原地球科学卓越中心, 北京 100101

基金项目: 国家自然科学基金项目（41125015，41474040，41274002）资助


详细信息

作者简介: 白一鸣, 男, 1993年生, 博士研究生, 主要从事地球内部结构研究.E-mail:baymax@mail.iggcas.ac.cn

通讯作者: 艾印双, 男, 1966年生, 研究员, 博士生导师, 主要从事地球内部结构研究.E-mail:ysai@mail.iggcas.ac.cn

中图分类号: P315

收稿日期:2017-10-31
修回日期:2017-12-18
上线日期:2018-02-05

Structure of the mantle transition zone beneath the southeastern Tibetan plateau revealed by P-wave receiver functions

BAI YiMing^1,2,,
AI YinShuang^1,2,3,,,
JIANG MingMing^1,3,
HE YuMei^1,3,
CHEN QiFu^1,2
1. Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
2. College of Earth Science, University of Chinese Academy of Sciences, Beijing 100049, China
3. CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100101, China


More Information

Corresponding author: AI YinShuang,E-mail:ysai@mail.iggcas.ac.cn

MSC: P315

--> Received Date: 31 October 2017
Revised Date: 18 December 2017
Available Online: 05 February 2018


摘要
摘要:研究青藏高原东南缘的深部结构对于理解印度-欧亚板块的碰撞机理和青藏高原的形成演化具有重要的科学意义.本研究对布设在研究区域内566个固定和流动地震台站的波形资料进行了处理，获得77853条高质量P波接收函数，应用接收函数共转换点（CCP）叠加技术获得了研究区域下方精细的地幔转换带间断面起伏形态及转换带厚度变化图像.结果表明：研究区域南北方向上具有两个明显的转换带增厚异常区，南侧异常区位于滇中次级块体与印支块体下方，可能是新特提斯洋板片与上部印度板块间断离并部分滞留在转换带底部的结果；北侧川西地区异常增厚可能与上方岩石圈拆沉并降至转换带有关；腾冲火山起源可能是板块俯冲过程中发生断离造成软流圈物质部分熔融，湿热物质上涌所致.
关键词: 地幔转换带/
青藏高原东南缘/
P波接收函数

Abstract:The deep structure of the southeastern Tibetan plateau is of great importance to a better understanding of the India-Eurasia collision as well as the evolution of the Tibetan plateau. In this study, we collected waveform data of 566 permanent and temporary seismic stations in southeastern Tibetan plateau, then extracted a total of 77853 high quality P-wave receiver functions using the maximum entropy deconvolution method. By the Common Conversion Point (CCP) stacking technique, we mapped the topography of the 410-and 660-km discontinuities ('410' and '660' hereinafter), and further investigated the lateral variation of the mantle transition zone (MTZ) beneath this region. The background velocity model deduced from H-κ stacking results and a previous body-wave tomographic research were applied to the correction of the crustal and upper mantle heterogeneities beneath southeastern Tibetan plateau for CCP stacking. Our results reveal two significantly thickened MTZ anomalies aligned nearly in the south-north direction. The magnitudes of both anomalies are~30 km above the global average of 250 km. The southern anomaly located beneath the central-Yunnan sub-block and the Indo-China block is characterized by a slightly deeper '410' and a greater-than-normal '660', while the northern anomaly beneath western Sichuan has an uplifted '410' and a depressed '660'. Combining with previous studies in the adjacent regions, we suggest that after slab break-off between the Indian plate and Neo-Tethys oceanic plate, the remnant of the latter stagnating at the bottom of the MTZ may have caused the southern anomaly in our receiver function images. The anomaly in the north, on the other hand, might be the consequence of the delamination of the overlying lithosphere sinking into the MTZ. The origin of the Tengchong volcano is probably connected to the upwelling of the hot and wet asthenospheric material caused by the slab break-off process.
Key words:Mantle transition zone/
Southeastern Tibetan plateau/
P-wave receiver functions



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