Experimental modeling of role of gravity and lateral shortening in Zagros mountain belt

Dynamically scaled analogs of the geologic structures of the Zagros mountain belt are used to argue that different parts of the Zagros Mountains of Iran record different combinations of the effects of a gravity-driven overturn and a southwest-northeast lateral shortening superimposed on the Zagros overturn. Partially scaled material models have been used to simulate the Zagros geodynamics, which involve layer-parallel compression of a 6 to 7km-thick Phanerozoic carbonate cover containing a pattern of preshortening diapirs. The folds in the Zagros form rapidly (1.5mm/yr in a 20 to 30km wide zone), reactivate some of the preshortening diapirs, and generate new synshortening listric diapirs. A third set of postshortening diapirs rises from the Hormuz decollement behind the fold-thrust front. Model buckle folds superimposed on diapirs or pillows tend to avoid and curve around preshortening diapirs, which flatten in the synclines. Model profiles show that lateral shortening induces residual salt at depth to flow toward and rise through the anticlinal cores as synshortening or postshortening diapirs. -from Author