Late Cenozoic volcanism and rates of active faulting in eastern Iran

• Published in: Geophysical journal international Vol. 177; no. 2; pp. 783 - 805
• Main Authors: Walker, R. T., Gans, P., Allen, M. B., Jackson, J., Khatib, M., Marsh, N., Zarrinkoub, M.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.05.2009
• Subjects: Asia; Continental tectonics: strike-slip and transform; Intra-plate processes; Rheology: crust and lithosphere; Rheology: crust and lithosphere; Intra-plate processes; Asia; Continental tectonics: strike-slip and transform
• ISSN: 0956-540X; 1365-246X
• DOI: 10.1111/j.1365-246X.2008.04024.x

We present new 40Ar/39Ar ages of samples of volcanic rock exposed along the remote margins of the Dasht-e Lut desert in eastern Iran. Close spatial relationships between the volcanic rocks and the trace of active strike-slip faults allow us to determine the slip rates of two major faults, averaged since eruption of the volcanics. Our study shows that the Nayband fault at the western margin of the Dasht-e Lut has a slip rate of ∼1.4 ± 0.5 mm yr−1 averaged over 2.25 Ma. The East Neh fault, one of several active strike-slip faults within the Sistan Suture Zone at the eastern margin of the Dasht-e Lut, has a minimum slip rate of ∼1.2 mm yr−1 averaged over ∼1.7 Ma. The rates of slip on major active faults in eastern Iran are largely unknown, and the slip rates our data provide, though limited, are a significant increase on what is known of the faulting within this remote and relatively inaccessible desert region. We also present analyses of the major and trace element concentrations within the volcanic rocks. The chemistry of the volcanic rocks is typical of intracontinental melts with an overall signature similar to that of ocean island basalts. Inversion of rare earth element distributions suggests some melting has occurred at depths of ∼80 km, indicating the presence of a relatively thin lithosphere beneath eastern Iran, in agreement with recently published maps of lithospheric thickness derived from shear wave velocities.