TY - JOUR

T1 - What controls structural variations along the Zagros Collision Zone? Insights from geophysical observations and thermo-mechanical modelling

AU - Tesauro, Magdala

AU - Maierová, Petra

AU - Koptev, Alexander

AU - Pastorutti, Alberto

AU - Pivetta, Tommaso

AU - Koulakov, Ivan

AU - Braitenberg, Carla

N1 - This study is supported by the PRIN 2017 project \u2018Intraplate deformation, magmatism and topographic evolution of a diffuse collisional belt: Insights into the geodynamics of the Arabia-Eurasia collisional zones\u2019 (MT, AP, TP, CB) and by project no. 23-08249S of the Czech Science Foundation (PM). We acknowledge Taras Gerya for providing the computer code used to generate our thermo-mechanical numerical models. We thank Paolo Ballato for useful references and two anonymous reviewers for valuable and constructive comments.

PY - 2024

Y1 - 2024

N2 - The Zagros Collision Zone is a complex tectonic region formed as a consequence of the collision between Arabia and Eurasia after the subduction of the Neo-Tethys ocean. The NW-SE striking Zagros orogen consists of the following parallel tectonic units (from SW to NE): Zagros Fold and Thrust Belt (ZFTB), Sanandaj–Sirjan Metamorphic Zone (SSZ), and Urumieh–Dokhtar Magmatic Arc (UDMA). In this study, we perform a combined analysis of recent geophysical data, revealing pronounced differences in the crustal and lithospheric structure along the Zagros Mountains. The northwestern sector shows a fairly uniform crustal thickening across the broad symmetric orogen from the ZFTB to the UDMA. In contrast, in the central Zagros, the transition from a relatively narrow zone of high elevations and high-frequency relief in the ZFTB to a smoother surface topography of the SSZ and UDMA occurs with an abrupt increase in Moho depth below the SSZ. The last observation has recently been interpreted as a result of “relamination” process, where the felsic upper crust of the Arabian plate underthrust the mafic crust of the Iranian plate. We present geodynamic numerical models of crustal relamination during continental collision and compute static gravity field of the resulting structures. We show that oblique closure of the Neo-Tethys affects lateral variations in the style and extent of crustal relamination, which control the observed along-strike changes in crustal configuration and orogen altitude. In particular, a narrow and higher orogen (as in the central Zagros) develops in the experiments with a young and wide oceanic plate, whereas an old and narrow subducting plate tends to form a broad and lower topography (as in the northwestern Zagros). This is geometrically consistent with the progressive closure of the Neo-Tethys from NW to SE during the oblique continental collision between Arabia and Eurasia.

AB - The Zagros Collision Zone is a complex tectonic region formed as a consequence of the collision between Arabia and Eurasia after the subduction of the Neo-Tethys ocean. The NW-SE striking Zagros orogen consists of the following parallel tectonic units (from SW to NE): Zagros Fold and Thrust Belt (ZFTB), Sanandaj–Sirjan Metamorphic Zone (SSZ), and Urumieh–Dokhtar Magmatic Arc (UDMA). In this study, we perform a combined analysis of recent geophysical data, revealing pronounced differences in the crustal and lithospheric structure along the Zagros Mountains. The northwestern sector shows a fairly uniform crustal thickening across the broad symmetric orogen from the ZFTB to the UDMA. In contrast, in the central Zagros, the transition from a relatively narrow zone of high elevations and high-frequency relief in the ZFTB to a smoother surface topography of the SSZ and UDMA occurs with an abrupt increase in Moho depth below the SSZ. The last observation has recently been interpreted as a result of “relamination” process, where the felsic upper crust of the Arabian plate underthrust the mafic crust of the Iranian plate. We present geodynamic numerical models of crustal relamination during continental collision and compute static gravity field of the resulting structures. We show that oblique closure of the Neo-Tethys affects lateral variations in the style and extent of crustal relamination, which control the observed along-strike changes in crustal configuration and orogen altitude. In particular, a narrow and higher orogen (as in the central Zagros) develops in the experiments with a young and wide oceanic plate, whereas an old and narrow subducting plate tends to form a broad and lower topography (as in the northwestern Zagros). This is geometrically consistent with the progressive closure of the Neo-Tethys from NW to SE during the oblique continental collision between Arabia and Eurasia.

KW - Crustal relamination

KW - Forward gravity models

KW - Geophysical data

KW - Oblique collision

KW - Thermo-mechanical modelling

KW - Zagros orogen

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-85196964215&origin=inward&txGid=49e10b51ab48b12ac14582f1f527e361

UR - https://www.mendeley.com/catalogue/3773292f-2f47-31c1-8c91-e9d4c140618e/

U2 - 10.1016/j.gr.2024.06.009

DO - 10.1016/j.gr.2024.06.009

M3 - Article

VL - 133

SP - 297

EP - 322

JO - Gondwana Research

JF - Gondwana Research

SN - 1342-937X

ER -