Lateral Structural Variation of the Lithosphere‐Asthenosphere System in the Northeastern to Eastern Iranian Plateau and Its Tectonic Implications

Abstract

The Iranian plateau in the central part of the Alpine-Himalayan orogenic system (Figure 1a) was formed as a consequence of the long-standing convergence between Eurasia and Gondwana-derived fragments, especially the Cenozoic closure of the Neo-Tethyan ocean and subsequent Arabia-Eurasia continental collision (see review by Agard et al., 2011). The causes of the plateau formation remain highly disputed and the role of crustal/lithospheric shortening and thickening (

Origin, Accretion, and Reworking of Continents

“…In either model, the development of the MLD or the LAB is closely linked to the evolution and reworking of continents, which is yet to be fully understood. In addition to the MLD commonly observed at ∼70-100 km depth, recent studies also detect other deeper discontinuities with either velocity increase or decrease with depth within or immediately below subcontinental lithospheric mantle (e.g., Calò et al, 2016;Sodoudi et al, 2013;Wu et al, 2021), implying more complicated vertical structural variations beneath continents.…”

“…In either model, the development of the MLD or the LAB is closely linked to the evolution and reworking of continents, which is yet to be fully understood. In addition to the MLD commonly observed at ~70-100 km depth, recent studies also detect other deeper discontinuities with either velocity increase or decrease with depth within or immediately below subcontinental lithospheric mantle (e.g., Calò et al, 2016;Sodoudi et al, 2013;Wu et al, 2021), implying more complicated vertical structural variations beneath continents. Overall, it is the long history of evolution and particularly complex reworking of continents that result in the present-day striking structural heterogeneities, not only laterally but also vertically, of the continental lithosphere compared to its oceanic…”

Tectonic evolution and geodynamics of the Neo-Tethys Ocean

“…Meanwhile, a shallower (<45 km) and a deeper Moho (ca. 50-55 km) are also observed beneath eastern and northeastern Iran, respectively, suggesting similar crustal deformation to mantle lithosphere but different patterns laterally (Wu et al, 2021). Combining the new seismic imaging results with geological and petrological constraints, Wu et al (2021) proposed that the thick crust (50-55 km) and lithospheric root (ca.…”

“…50-55 km) are also observed beneath eastern and northeastern Iran, respectively, suggesting similar crustal deformation to mantle lithosphere but different patterns laterally (Wu et al, 2021). Combining the new seismic imaging results with geological and petrological constraints, Wu et al (2021) proposed that the thick crust (50-55 km) and lithospheric root (ca. 120 km) in northeastern Iran may result from the distal and localized deformation during the Arabia-Eurasia collision that thickened the entire lithosphere, whereas the thinner and less deformed crust (<45 km) and lithosphere (80-90 km) in eastern Iran may be the consequence of limited post-collisional lithospheric thickening and multi-phase lithospheric thinning since the Eocene.…”

“…780 km convergence was accommodated by the Africa-Arabia and Eurasia collision (van der Boon et al, 2018), which provide new clue for studies of lithospheric deformation and plateau uplift. Wu et al (2021) used S-wave receiver function data from a dense seismic array to construct the structural image of the lithosphere-asthenosphere system across the northeastern to eastern Iranian plateau. The data show that the lithosphere-asthenosphere boundary (LAB) beneath the Iran plateau is relatively flat at 80-90 km depth in eastern Iran, but deepens northward to ca.…”