Crustal and lithospheric structure of the Alborz Mountains, Iran, and surrounding areas from integrated geophysical modeling

Using gravity, geoid, topography and surface heat flow data, we have modeled the density and temperature distribution in the lithosphere along three profiles crossing Iran in SW‐NE direction from the Arabian foreland in the SW to the South Caspian Basin and the Turan Platform to the NE. We find thin lithosphere (100–120 km) underneath central Iran, whereas thick lithosphere (up to 240 km) is found underneath Arabia, the South Caspian Basin and the Turan Platform. Crustal thickening is found under the Zagros and Alborz mountains (up to 60 km) and under the Kopet‐Dagh Mountains (48 km), whereas the thin crust under the southern Caspian Sea is either an oceanic crust or a highly thinned continental one. Below the South Caspian Sea, the shape of the crust‐mantle interface and the base of the lithosphere indicate a subduction of the South Caspian block toward the N‐NW. Further east, under the Kopet‐Dagh, no evidence for active subduction is visible. This can be explained by a rheologically very strong South Caspian block, surrounded by weaker continental lithosphere. Key Points Thick crust under Alborz Mountains Northward subduction of South Caspian lithosphere No subduction under Kopet Dagh Mountains