The Oligo-Miocene Marine Environments of Central Iran - Intra- and Back-Arc Extensions

Hassanzadeh, Jamshid; Fakhari, Mohammad

doi:10.3997/2214-4609-pdb.131.gen1997_d014

Cited by 1 publication

(1 citation statement)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Basalts were predominant during this period because the thinned crust contributed relatively little contamination and was an ineffective density barrier to primitive magmas [Plank and Langmuir, 1988;Glazner and Ussler, 1989]. Given stratigraphic evidence for continued extension and subsidence during deposition of the Oligo-Miocene Qom Formation [e.g., Hassanzadeh and Fakhari, 1997], the late Eoceneearly Oligocene transition from extensive arc magmatism to limited asthenosphere-derived volcanism may have occurred when the supply of fertile, preconditioned lithospheric mantle was exhausted. Subsequent post-late Miocene (i.e., postcollisional) adakitic volcanism in the Urumieh-Dokhtar arc may be related to slab break-off, as suggested by Jahangiri [2007], Omrani et al [2008], and Hassanzadeh et al [2009].…”

Section: Tectonic Model For the Eocene Magmatic Flare-upmentioning

confidence: 98%

A Paleogene extensional arc flare‐up in Iran

et al. 2011

View full text Add to dashboard Cite

[1] Arc volcanism across Iran is dominated by a Paleogene pulse, despite protracted and presumably continuous subduction along the northern margin of the Neotethyan ocean for most of Mesozoic and Cenozoic time. New U-Pb and 40 Ar/ 39 Ar data from volcanic arcs in central and northern Iran constrain the duration of the pulse to ∼17 Myr, roughly 10% of the total duration of arc magmatism. Late Paleocene-Eocene volcanic rocks erupted during this flare-up have major and trace element characteristics that are typical of continental arc magmatism, whereas the chemical composition of limited Oligocene basalts in the Urumieh-Dokhtar belt and the Alborz Mountains which were erupted after the flare-up ended are more consistent with derivation from the asthenosphere. Together with the recent recognition of Eocene metamorphic core complexes in central and east central Iran, stratigraphic evidence of Eocene subsidence, and descriptions of Paleogene normal faulting, these geochemical and geochronological data suggest that the late Paleocene-Eocene magmatic flare-up was extension related. We propose a tectonic model that attributes the flare-up to decompression melting of lithospheric mantle hydrated by slab-derived fluids, followed by Oligocene upwelling and melting of enriched mantle that was less extensively modified by hydrous fluids. We suggest that Paleogene magmatism and extension was driven by an episode of slab retreat or slab rollback following a Cretaceous period of flat slab subduction, analogous to the Laramide and post-Laramide evolution of the western United States.

show abstract