赵文津,,
史大年,
刘志伟,
杨艳
中国地质科学院, 北京 100037
基金项目: 中国大地构造演化和国际亚洲大地构造图编制(中国地质科学院)，国家自然科学基金项目(41674099)联合资助
详细信息
作者简介: 赵荣涛, 男, 1990年生, 博士研究生, 主要从事地震学研究.E-mail:rongtaozhao@126.com
通讯作者: 赵文津, 男, 1931年生, 中国工程院院士, 研究方向为矿产勘查、深部探测及青藏高原地质.E-mail:xzwzwj@sina.com
中图分类号: P315收稿日期:2019-12-03
修回日期:2020-05-13
上线日期:2020-08-05
Seismic evidence for northward subduction of the Hoh Xil lithosphere beneath the Qaidam Basin
ZHAO RongTao,ZHAO WenJin,,
SHI DaNian,
LIU ZhiWei,
YANG Yan
Chinese Academy of Geological Sciences, Beijing 100037, China
More Information
Corresponding author: ZHAO WenJin,E-mail:xzwzwj@sina.com
MSC: P315--> Received Date: 03 December 2019
Revised Date: 13 May 2020
Available Online: 05 August 2020
摘要
摘要:利用中美德INDEPTH IV合作项目2007—2009年间布置于青藏高原中、北部140个宽频地震台站记录到的天然地震数据，经过接收函数成像处理，获得了3条穿过昆仑—阿尼玛卿缝合带清晰的壳幔结构图像.结果显示柴达木南缘莫霍面位于约50 km深度，羌塘地块、可可西里地块、东昆仑造山带莫霍面位于约65 km深度，昆仑—阿尼玛卿缝合带以北约50 km存在莫霍面深度突变.在可可西里和柴达木岩石圈地幔之间观测到北倾界面，这可能是可可西里岩石圈向北俯冲到柴达木地幔之下的证据.可可西里地块地壳内宽缓的负转换震相带是低速带的反映，其向北挤入到东昆仑山下发生挤压增厚，可能是东昆仑山隆升的原因；由于刚性柴达木岩石圈的阻挡，物质向东改向，则可能是该地区向东旋转的构造应力场产生的原因.本文研究结果不支持亚洲岩石圈地幔在东昆仑—柴达木交界处向南俯冲，据此，我们提出了新的东昆仑造山模式.
关键词: 东昆仑山/
P波接收函数成像/
可可西里地块/
地幔岩石圈/
造山模式
Abstract:We obtained three P-wave receiver function profiles across the Kunlun-Anyêmaqên suture using the data recorded by 140 broadband seismic stations deployed by the INDEPTH IV project in the middle-northern Tibetan plateau during 2007 and 2009. The Moho discontinuity is observed distinctly and almost horizontally at a depth of ~50 km beneath the southern Qaidam basin,in contrast to the Moho depth at ~65 km beneath the Qiangtang terrain,the Hoh Xil terrain and the eastern Kunlun mountains,with a Moho offset observed ~50 km north of the Kunlun-Anyêmaqên suture. A north-dipping converter is observed just below the Moho offset,and is interpreted as evidence for northward subduction of the Hoh Xil lithosphere beneath the Qaidam basin. Some diffusely-distributed negative converted waves are observed beneath the Hoh Xil terrain,which may suggest a low-velocity zone (LVZ) derived from squeezing of the Hoh Xil crustal materials into the eastern Kunlun middle crust. The resistance of the rigid Qaidam lithosphere to the LVZ may account for the uplift of the eastern Kunlun mountains,and the eastward movement of the LVZ may be responsible for the clockwise rotation of the regional stress field in the eastern Kunlun orogen. Furthermore,the northward subduction of the Hoh Xil lithosphere argues against the southward subduction of the Asian lithospheric mantle below the Kunlun-Qaidam border. A new orogenic model for the building-up of the eastern Kunlun mountains is then proposed based on these results.
Key words:Eastern Kunlun mountains/
P-wave receiver function imaging/
Hoh Xil terrain/
Lithospheric structure/
Orogenic model
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