Geology and thermochronology of Tertiary Cordilleran-style metamorphic core complexes in the Saghand region of central Iran

Verdel, Charles, Wernicke, Brian P., Ramezani, Jahandar, Hassanzadeh, Jamshid, Renne, Paul R. and Spell, Terry L. (2007) Geology and thermochronology of Tertiary Cordilleran-style metamorphic core complexes in the Saghand region of central Iran. Geological Society of America Bulletin, 119 7-8: 961-977. doi:10.1130/B26102.1


Author Verdel, Charles
Wernicke, Brian P.
Ramezani, Jahandar
Hassanzadeh, Jamshid
Renne, Paul R.
Spell, Terry L.
Title Geology and thermochronology of Tertiary Cordilleran-style metamorphic core complexes in the Saghand region of central Iran
Journal name Geological Society of America Bulletin   Check publisher's open access policy
ISSN 0016-7606
1943-2674
Publication date 2007-07
Sub-type Article (original research)
DOI 10.1130/B26102.1
Volume 119
Issue 7-8
Start page 961
End page 977
Total pages 17
Place of publication Boulder, CO, United States
Publisher Geological Society of America
Language eng
Formatted abstract
An ∼100-km-long north-south belt of metamorphic core complexes is localized along the boundary between the Yazd and Tabas tectonic blocks of the central Iranian micro-continent, between the towns of Saghand and Posht-e-Badam. Amphibolite facies mylonitic gneisses are structurally overlain by east-tilted supracrustal rocks including thick (>1 km), steeply dipping, nonmarine siliciclastic and volcanic strata. Near the detachment (the Neybaz-Chatak fault), the gneisses are generally overprinted by chlorite brecciation. Crosscutting relationships along with U-Pb zircon and 40Ar/39Ar age data indicate that migmatization, mylonitic deformation, volcanism, and sedimentation all occurred in the middle Eocene, between ca. 49 and 41 Ma. The westernmost portion of the Tabas block immediately east of the complexes is an east-tilted crustal section of Neoproterozoic–Cambrian crystalline rocks and metasedi-mentary strata >10 km thick. The 40Ar/39Ar biotite ages of 150–160 Ma from structurally deep parts of the section contrast with ages of 218–295 Ma from shallower parts, and suggest Late Jurassic tilting of the crustal section. These results define three events: (1) a Late Jurassic period of upper crustal cooling of the western Tabas block that corresponds to regional Jurassic–Cretaceous tectonism and erosion recorded by a strong angular unconformity below mid-Cretaceous strata throughout central Iran; (2) profound, approximately east-west middle Eocene crustal extension, plutonism, and volcanism (ca. 44–40 Ma); and (3) ∼2–3 km of early Miocene (ca. 20 Ma) erosional exhumation of both core complex and Tabas block assemblages at uppermost crustal levels, resulting from significant north-south shortening. The discovery of these and other complexes within the mid-Tertiary magmatic arcs of Iran demonstrates that Cordilleran-style core complexes are an important tectonic element in all major segments of the Alpine-Himalayan orogenic system.
Keyword Metamorphic core complex
Extensional tectonics
Thermochronology
Iran
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Earth Sciences Publications
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Created: Wed, 12 Oct 2011, 17:10:57 EST by Charles Verdel on behalf of School of Earth Sciences