The Crust and Upper Mantle Structure of Central and West Antarctica From Bayesian Inversion of Rayleigh Wave and Receiver Functions
The Crust and Upper Mantle Structure of Central and West Antarctica From Bayesian Inversion of Rayleigh Wave and Receiver Functions
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DOI：
10.1029/2017jb015346
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发表时间：
2018-09
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通讯作者：
W. Shen;D. Wiens;S. Anandakrishnan;R. Aster;P. Gerstoft;P. Bromirski;S. Hansen;I. Dalziel;D. Heeszel;A. Huerta;A. Nyblade;R. Stephen;Terry J. Wilson;J. P. Winberry
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作者：
W. Shen;D. Wiens;S. Anandakrishnan;R. Aster;P. Gerstoft;P. Bromirski;S. Hansen;I. Dalziel;D. Heeszel;A. Huerta;A. Nyblade;R. Stephen;Terry J. Wilson;J. P. Winberry
我们通过联合反演瑞利波相速度和群速度以及P波接收函数，构建了一个南极中部和西部的新地震模型。利用过去18年中部署的200多个地震台站的数据进行的环境噪声层析成像被用于构建瑞利波相速度和群速度频散图。将环境噪声相速度图与利用远震构建的相速度图进行比较，证实了两种结果的准确性。这些图与P波接收函数波形一起，使用贝叶斯蒙特卡洛算法构建了一个新的地壳和最上部地幔的三维剪切波速度（Vs）模型。这个新的三维地震模型显示了构造活动的西南极洲（WANT）和稳定古老的东南极洲（EANT）的二分性。在WANT中，该模型显示沿横贯南极山脉（TAMs）前缘的最上部地幔速度较慢，这被解释为新生代裂谷作用的热效应。在南部TAMs下方，速度较慢的最上部地幔在传统上认为的EANT下方水平延伸，推测这与岩石圈拆沉有关。沿阿蒙森海海岸观察到的薄地壳和岩石圈并向内陆延伸，表明这些区域参与了新生代裂谷作用。EANT具有相对较厚且寒冷的地壳和以高Vs为特征的岩石圈，在最上部地幔的甘布尔采夫冰下山脉下方显示出一个较慢的Vs异常，我们推测这可能是一个成分异常体的标志，也许是大陆碰撞的残余。
We construct a new seismic model for central and West Antarctica by jointly inverting Rayleigh wave phase and group velocities along with P wave receiver functions. Ambient noise tomography exploiting data from more than 200 seismic stations deployed over the past 18 years is used to construct Rayleigh wave phase and group velocity dispersion maps. Comparison between the ambient noise phase velocity maps with those constructed using teleseismic earthquakes confirms the accuracy of both results. These maps, together with P receiver function waveforms, are used to construct a new 3‐D shear velocity (Vs) model for the crust and uppermost mantle using a Bayesian Monte Carlo algorithm. The new 3‐D seismic model shows the dichotomy of the tectonically active West Antarctica (WANT) and the stable and ancient East Antarctica (EANT). In WANT, the model exhibits a slow uppermost mantle along the Transantarctic Mountains (TAMs) front, interpreted as the thermal effect from Cenozoic rifting. Beneath the southern TAMs, the slow uppermost mantle extends horizontally beneath the traditionally recognized EANT, hypothesized to be associated with lithospheric delamination. Thin crust and lithosphere observed along the Amundsen Sea coast and extending into the interior suggest involvement of these areas in Cenozoic rifting. EANT, with its relatively thick and cold crust and lithosphere marked by high Vs, displays a slower Vs anomaly beneath the Gamburtsev Subglacial Mountains in the uppermost mantle, which we hypothesize may be the signature of a compositionally anomalous body, perhaps remnant from a continental collision.