Deep structure of the Sistan continental collision zone from nonlinear teleseismic tomography
عنوان دوره: نوزدهمین کنفرانس ژئوفیزیک ایران
کد مقاله : 1528-NIGS
نویسندگان
1پژوهشگاه زلزله شناسی و مهندسی زلزله
2پژوهشگاه بین المللی زلزله شناسی و مهندسی زلزله
چکیده
In this study, we used the records of teleseismic earthquakes from a dense passive array of 36 seismometers to investigate the lithospheric and uppermost mantle structures beneath the Sistan suture zone. Teleseismic data from 240 events with high signal-to-noise ratios were recorded during the nine-month deployment period of the array, from which 3992 relative arrival time residuals were picked. We used a nonlinear teleseismic tomography method to map the relative arrival time residuals as 3D perturbations in P-wave velocity beneath the suture zone down to depths of 370 km. The solution model indicates a number of features that have important ramifications for the interpretation of the tectonic history in the region. The most prominent feature is the presence of a low-velocity anomaly beneath the high elevations in the region. The low-velocity anomaly extends to depths as much as 120 km, beneath which a high-velocity anomaly is observed. This feature may indicate the presence of melts due to the delamination of the base of the lithosphere and asthenospheric upwelling as a response to continental collision.
کلیدواژه ها
Title
Deep structure of the Sistan continental collision zone from nonlinear teleseismic tomography
Authors
Meysam Mahmoodabadi, Farzam Yaminifard, Mohammad Tatar, Ali Hashemi Gazar
Abstract
In this study, we used the records of teleseismic earthquakes from a dense passive array of 36 seismometers to investigate the lithospheric and uppermost mantle structures beneath the Sistan suture zone. Teleseismic data from 240 events with high signal-to-noise ratios were recorded during the nine-month deployment period of the array, from which 3992 relative arrival time residuals were picked. We used a nonlinear teleseismic tomography method to map the relative arrival time residuals as 3D perturbations in P-wave velocity beneath the suture zone down to depths of 370 km. The solution model indicates a number of features that have important ramifications for the interpretation of the tectonic history in the region. The most prominent feature is the presence of a low-velocity anomaly beneath the high elevations in the region. The low-velocity anomaly extends to depths as much as 120 km, beneath which a high-velocity anomaly is observed. This feature may indicate the presence of melts due to the delamination of the base of the lithosphere and asthenospheric upwelling as a response to continental collision.
Keywords
Continental collision, lithosphere, Sistan suture zone, Teleseismic tomography