Data Services Products: EMC-IPcrust2022 Iranian Plateau crustal shear wave model

Summary

IPcrust2022 is a two-dimensional shear-wave model of the Iranian Plateau crust and uppermost mantle from a joint analysis of fundamental mode Rayleigh wave group velocities and P-wave receiver functions.

Description

Name IPcrust2022
Title Iranian Plateau crustal shear wave model
Type 2-D shear wave crustal model
Sub Type S Velocity
Year 2022
Data Revision r0.0 (revision history)
 
Short Description   IPcrust2022 is a two-dimensional shear-wave (Vs) model of the Iranian Plateau crust and uppermost mantle derived from a joint analysis of fundamental mode Rayleigh wave group velocities and P-wave receiver functions. The model covers an area from 39.25E, 45.25N in the northwest to 25.25E, 62.25N in the southeast and is contained in a single, gzipped file consisting of seven columns — latitude and longitude in degrees, elevation in kilometers, Moho and Moho depth error in kilometers, and upper crustal, lower crustal and uppermost mantle Vs in km/s. At the boundaries IPcrust2022 is blended into CRUST1.0. The thickest crust (>55 km) is located beneath the Sanandaj-Sirjan Zone (SSZ) and the deforming belts of the Alborz-Binalud-Kopet Dag Mountains. Regions of lower topography/deformation (e.g., central Iran and the Lut Block), and the regions of younger deformation such as the Makran Accretionary Wedge (MAW) and the Zagros Simply Folded Belt (SFB) have a thinner (<45 km) crust. There is a low-Vs, tongue-shaped feature extending from the upper crust of the Zagros to the lower crust of the SSZ and Urumieh–Dokhtar Magmatic Arc (UDMA), suggesting an underthrusting of the Arabian crust beneath central Iran. In the central Zagros, the underthrusting of the Arabian crust is steeper, resulting in a narrower deforming zone (∼150 km) and a thicker crust (∼60–65 km), compared to the NW or SE Zagros where the deforming zone is broader (∼250 km) and the crust is thinner (∼55–60 km). Regions of low Vs in the upper crust correspond to regions of thick sediments: the South Caspian Basin, the Zagros SFB and Foreland Basin, and the MAW. The subcrustal Rayleigh wave azimuthal anisotropy of the Plateau shows a rather uniform and smoothly-varying pattern. In the NW Zagros, the crustal and subcrustal pattern of anisotropy agrees with that previously estimated from the shear-wave core phases, implying that the whole lithosphere deforms coherently, but for other regions (e.g., the western Alborz and Kopet Dag), the anisotropic pattern does not support a coherent deformational fabric throughout the lithosphere.
 
Authors: Mohsen A. Irandoust, Department of Earth Sciences Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan, Iran

Keith Priestley, Bullard Laboratories Department of Earth Sciences University of Cambridge, Cambridge, United Kingdom

Farhad Sobouti, Department of Earth Sciences Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan, Iran
 
Reference Model None
 
Prior Model None
 
Model Home Page https://www.esc.cam.ac.uk/directory/keith-priestley
 
Model Download IPCRUST.2022.r0.0.nc (see metadata) is the model with topography in netCDF 3 Classic format.
 
Depth Coverage crust and sub-moho mantle
 
Area Iranian Plateau (latitude: 25.25° to 39.25°, longitude: 44.75° to 62.25°)
 
Data Set Description Model IPcrust consists of the crust and sub-Moho mantle shear-wave velocity (Vs) structure at 672 points on an equispaced, quarter degree by quarter degree geographic grid covering an area extending from 39.25E, 45.25N in the northwest to 25.25E, 62.25N in the southeast. Model IPcrust is contained in a single gzipped file consisting of, for each geographic point, seven values — latitude and longitude in degrees, elevation in kilometers, Moho and Moho depth error in kilometers, and upper crustal, lower crustal and uppermost mantle Vs in km/s.
 
 

Figure 1
Figure 1. Map showing the seismograph recording sites (yellow circles) and the receiver function interpolation scheme (black and red stars). Black stars denote cell centers with at least two observed receiver functions within 1 degree of the cell center with the Vs structure constrained by a receiver function and surface wave measurement; red stars denote cell centers with only a surface wave constrains. Examples of the crustal model constraints for IPcrust2022 are shown surrounding the map with the geographic sites indicated by the black lines. For sites denoted by the black stars, there are three sub-plots. The first sub-plot shows the mean receiver function (solid black line) with the corresponding error bands (dashed gray lines), the synthetic receiver function for the final inversion crustal model (solid red line), and the synthetic receiver function for the two-layer crustal model with the Moho depth (green line). The second sub-plot shows the observed dispersion curve (black circles with error bars) with the synthetic dispersion curve for the inversion crustal model (solid red line), and the synthetic dispersion curve for the two-layer model (solid green line). The third sub-plot shows the inversion Vs crustal model (solid red line), the two-layer initial model (dashed light-blue line), and the result of the observed dispersion curve inversion with the initial model (solid green line). For locations with no interpolated receiver functions (red stars), the crustal structure is constrained only by the fundamental mode Rayleigh wave group velocity dispersion. For details of the data and analysis, see Irandoust et al (2022).

Figure 2
Figure 2. (a–c) Lateral variations in the average Vs for (a) the upper crust (<15 km-depth), (b) the lower crust (>15 km-depth), and (c) the sub-Moho mantle (<110 km) for IPcrust2022. Earthquakes with magnitude 5 and greater and in the same depth range are plotted as circles in maps shown in panels (a–c). The black lines over-plotted on the lower crustal Vs map (b) show the locations of the crustal cross-sections seen in Figure 3. The lateral variation of sub-Moho Vs and azimuthal anisotropy (black bars) are shown in (c). Over-plotted on (c) are the variations in the GPS-observed deformation field (red arrows) and Absolute Plate Motion field vectors (brown arrows). (d) The lateral variation in crustal thickness for the Iranian Plateau. The + symbols denote points at which the crustal thickness is calculated in this study (see Figure 1). IPcrust2022 is merged with CRUST1.0 in the surrounding region. (e) Moho depth error map. (f) Variation of Bouguer gravity anomaly. A Vs scale for (a–c) is given under (c) and scales for Moho depth, Moho depth error, and Bouguer gravity anomaly are plotted beside (d–f), respectively.

Figure 3a
Figure 3a. Profiles along the lines shown in Figure 2b. For each profile, the panels from top to bottom show topography with main geological features, interpolated receiver functions, the 1D Vs models variations with depth (black where derived from joint inversion and gray where derived from surface wave inversion only), and 2D image of shear-wave velocity cross-sections. The white circles with an error bar on the velocity maps indicate the Moho depths and the solid white line shows the 3.1 km/s contour. The sedimentary cover is indicated by the red transparent area along different profiles. The earthquake focal mechanisms shown with blue indicate the compressional quadrants. Black small circles show earthquakes with magnitude 5 and greater between the years 2000 and 2019 from the ISC-EHB catalog (http://www.isc.ac.uk/isc-ehb/).

Figure 3b
Figure 3b. The figure format is the same as that shown in Figure 3a.

Citations and DOIs

To cite the original work behind this Earth model:

  • Irandoust, M. A., Priestley, K., & Sobouti, F. (2022). High-resolution lithospheric structure of the Zagros collision zone and Iranian Plateau. Journal of Geophysical Research: Solid Earth, 127, e2022JB025009. https://doi.org/10.1029/2022JB025009

To cite IRIS DMC Data Products effort:

  • Trabant, C., A. R. Hutko, M. Bahavar, R. Karstens, T. Ahern, and R. Aster (2012), Data Products at the IRIS DMC: Stepping Stones for Research and Other Applications, Seismological Research Letters, 83(5), 846–854, https://doi.org/10.1785/0220120032.

DOI for this EMC webpage: https://doi.org/10.17611/dp/emc.2023.ipcrust2022

References

  • G.C. Begg, W.L. Griffin, L.M. Natapov, Suzanne Y. O’Reilly, S.P. Grand, C.J. O’Neill, J.M.A. Hronsky, Y. Poudjom Djomani, C.J. Swain, T. Deen, P. Bowden; The lithospheric architecture of Africa: Seismic tomography, mantle petrology, and tectonic evolution. Geosphere 2009;; 5 (1): 23–50. https://doi.org/10.1130/GES00179.1

Credits

  • r0.0 model provided by Model provided by Keith Priestley. netCDF format conversion by EarthScope.

Revision History

revision r0.0: uploaded July 27, 2023.

Timeline

2023-10-20
r0.0 online

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