Geochronology and geochemistry of rhyolites from Hormuz Island, southern Iran: A new record of Cadomian arc magmatism in the Hormuz Formation

Faramarzi, Narges Sadat; Amini, Sadraddin; Schmitt, Axel K.; Hassanzadeh, Jamshid; Borg, Gregor; McKeegan, Kevin D.; Razavi, Seyed Mohammad Hosein; Mortazavi, Seyed Mohsen

doi:10.1016/j.lithos.2015.08.017

Cited by 59 publications

(15 citation statements)

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“…For comparison, a sample from a Cenozoic granite-related magnetite skarn deposit in the Sangan area in northeastern Iran was also analyzed. We studied the triple O isotope compositions of magnetite from the IOA deposits of the Yazd and Sirjan areas, in particular, because the country rocks of the felsic intrusions and their IOA deposits consist of limestone and evaporite rocks of late Ediacaran to early Cambrian age (Faramarzi et al, 2015). Evaporites from the Ediacaran and early Cambrian carry large 17 O deficits compared to evaporites that formed later in the Phanerozoic (Bao et al, 2008;Crockford et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Triple oxygen isotope variations in magnetite from iron-oxide deposits, central Iran, record magmatic fluid interaction with evaporite and carbonate host rocks

Peters

Alibabaie

Pack

et al. 2019

Geology

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Oxygen isotope ratios in magnetite can be used to study the origin of iron-oxide ore deposits. In previous studies, only 18O/16O ratios of magnetite were determined. Here, we report triple O isotope data (17O/16O and 18O/16O ratios) of magnetite from the iron-oxide–apatite (IOA) deposits of the Yazd and Sirjan areas in central Iran. In contrast to previous interpretations of magnetite from similar deposits, the triple O isotope data show that only a few of the magnetite samples potentially record isotopic equilibrium with magma or with pristine magmatic water (H2O). Instead, the data can be explained if magnetite had exchanged O isotopes with fluids that had a mass-independently fractionated O isotope composition (i.e., MIF-O), and with fluids that had exchanged O isotopes with marine sedimentary carbonate rocks. The MIF-O signature of the fluids was likely obtained by isotope exchange with evaporite rocks of early Cambrian age that are associated with the IOA deposits in central Iran. In order to explain the triple O isotope composition of the magnetite samples in conjunction with available iron isotope data for magnetite from the deposits, we propose that magnetite formed from magmatic fluids that had interacted with evaporite and carbonate rocks at high temperatures and at variable water/rock ratios; e.g., magmatic fluids that had been released into the country rocks of a magma reservoir. Additionally, the magnetite could have formed from magmatic fluids that had exchanged O isotopes with SO2 and CO2 that, in turn, had been derived by the magmatic assimilation and/or metamorphic breakdown of evaporite and carbonate rocks.

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Section: Introductionmentioning

confidence: 99%

Triple oxygen isotope variations in magnetite from iron-oxide deposits, central Iran, record magmatic fluid interaction with evaporite and carbonate host rocks

Peters

Alibabaie

Pack

et al. 2019

Geology

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“…In other words, the absence of a seismically resolved prekinematic layer indicates that the Ara Salt started to move in Early Cambrian immediately after its deposition. Thus, we infer that the Hormuz Salt, deposited after ~ 558 ± 7 Ma (Faramarzi et al, 2015), might have begun flowing at a similar time (i.e. Cambrian).…”

Section: Initiation Of Salt Flow and Passive Diapirism Stagementioning

confidence: 88%

“…The famous diapir in the core of the Hormuz Island (Figures 2b and 8a) is the location of Hormuz Salt's first stratigraphic description (Pilgrim, 1908). Rhyolitic rocks in this diapir (Gansser, 1960;Player, 1969) have yielded a zircon age of ~ 558 ± 7 Ma mostly showing the lower depositional age limit of the Hormuz Salt (Faramarzi et al, 2015). The outcropping diapir is surrounded mainly by Pliocene and Quaternary sediments, but the Middle Miocene strata are dipping outwards at 60-80° along the southwest and southeast margins and are conglomeratic (diapir-derived debris) at the contact with the salt (Gansser, 1960;Talbot, Aftabi, & Chemia, 2009).…”

Section: Descriptionmentioning

confidence: 92%

“…Simplified stratigraphic chart and major tectonic events of the Eastern Persian Gulf and the Strait of Hormuz (left) along with the equivalent chart of the eastern part of the United Arab Emirates and the Oman Mountains (right) (modified after Al-Husseini, 2014, 2015Ali & Watts, 2009;Allen, 2007;Bowring et al, 2007;Jahani et al, 2009;James & Wynd, 1965;Piryaei et al, 2011). Approximate age of the base of Hormuz Salt is based on Faramarzi et al (2015) and age of pre-Hormuz sediments is considered equivalent to the Oman chart. Note that the geological timescale older than 550 Ma is nonlinear EAGE HASSANPOUR et Al.…”

Section: F I G U R Ementioning

confidence: 99%

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Salt tectonics in a double salt‐source layer setting (Eastern Persian Gulf, Iran): Insights from interpretation of seismic profiles and sequential cross‐section restoration

et al. 2020

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Salt tectonics in the Eastern Persian Gulf (Iran) is linked to a unique salt‐bearing system involving two overlapping ‘autochthonous’ mobile source layers, the Ediacaran–Early Cambrian Hormuz Salt and the Late Oligocene–Early Miocene Fars Salt. Interpretations of reflection seismic profiles and sequential cross‐section restorations are presented to decipher the evolution of salt structures from the two source layers and their kinematic interaction on the style of salt flow. Seismic interpretations illustrate that the Hormuz and Fars salts started flowing in the Early Palaeozoic (likely Cambrian) and Early Miocene, respectively, shortly after their deposition. Differential sedimentary loading (downbuilding) and subsalt basement faults initiated and localized the flow of the Hormuz Salt and the related salt structures. The resultant diapirs grew by passive diapirism until Late Cretaceous, whereas the pillows became inactive during the Mesozoic after a progressive decline of growth in the Late Palaeozoic. The diapirs and pillows were then subjected to a Palaeocene–Eocene contractional deformation event, which squeezed the diapirs. The consequence was significant salt extrusion, leading to the development of allochthonous salt sheets and wings. Subsequent rise of the Hormuz Salt occurred in wider salt stocks and secondary salt walls by coeval passive diapirism and tectonic shortening since Late Oligocene. Evacuation and diapirism of the Fars Salt was driven mainly by differential sedimentary loading in annular and elongate minibasins overlying the salt and locally by downslope gliding around pre‐existing stocks of the Hormuz Salt. At earlier stages, the Fars Salt flowed not only towards the pre‐existing Hormuz stocks but also away from them to initiate ring‐like salt walls and anticlines around some of the stocks. Subsequently, once primary welds developed around these stocks, the Fars Salt flowed outwards to source the peripheral salt walls. Our results reveal that evolving pre‐existing salt structures from an older source layer have triggered the flow of a younger salt layer and controlled the resulting salt structures. This interaction complicates the flow direction of the younger salt layer, the geometry and spatial distribution of its structures, as well as minibasin depocentre migration through time. Even though dealing with a unique case of two ‘autochthonous’ mobile salt layers, this work may also provide constraints on our understanding of the kinematics of salt flow and diapirism in other salt basins having significant ‘allochthonous’ salt that is coevally affected by deformation of the deeper autochthonous salt layer and related structures.

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“…3; Supplemental File 1 1 ). We used secondary ion mass spectrometry (CAMECA IMS 1270) for the analysis at the University of California, Los Angeles (UCLA), using the method described by Faramarzi et al (2015). This sample was taken from the stratigraphically lowest part of the middle plate, which crops out in southern part of Kuh-e-Yazdu (Fig.…”

Section: Geochronology and Thermochronology U-pb Geochronologymentioning

confidence: 99%

Large-magnitude continental extension in the northeastern Iranian Plateau: Insight from K-feldspar ⁴⁰ Ar/ ³⁹ Ar thermochronology from the Shotor Kuh–Biarjmand metamorphic core complex

et al. 2017

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The Late Cretaceous-early Paleogene tectonic evolution of the Iranian Plateau is not well understood in comparison to its well-studied late Paleogene-Neogene evolution. Exhumation, metamorphism, and changing sedimentary environments are documented away from the plateau margin for this time interval, however the nature and mechanism of deformation in the interior of the Iranian Plateau remains controversial to the point that both compressional and extensional mechanisms are proposed. We use K-feldspar and mica 40 Ar/ 39 Ar thermochronology to determine the thermal evolution of metamorphic rocks exposed in northeastern Great Kavir Basin on the Iranian Plateau. Multi-domain diffusion modeling of K-feldspar and field relationships reveal a stage of rapid cooling via tectonic exhumation starting in the Late Cretaceous and lasting until the early Eocene. We attribute this to continental extension as being accommodated on detachment faults that exhumed the Shotor Kuh-Biarjmand metamorphic core complex. The metamorphic rocks of this core complex underlie a southeastward-younging structural-stratigraphic sequence that includes at its top Late Cretaceous (Campanian-Maastrichtian) carbonates. We interpret this sequence as a crustal section that was exhumed by a NW-dipping master detachment fault. Based on the locations of the syn-extensional detrital rocks we propose that this system accommodated ~100 km of NW-SE-oriented extension. Our results indicate that extensional deformation started in the Iranian Plateau much earlier (Late Cretaceous) than previously thought (Eocene-Oligocene).

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Geochronology and geochemistry of rhyolites from Hormuz Island, southern Iran: A new record of Cadomian arc magmatism in the Hormuz Formation

Cited by 59 publications

References 47 publications

Triple oxygen isotope variations in magnetite from iron-oxide deposits, central Iran, record magmatic fluid interaction with evaporite and carbonate host rocks

Triple oxygen isotope variations in magnetite from iron-oxide deposits, central Iran, record magmatic fluid interaction with evaporite and carbonate host rocks

Salt tectonics in a double salt‐source layer setting (Eastern Persian Gulf, Iran): Insights from interpretation of seismic profiles and sequential cross‐section restoration

Large-magnitude continental extension in the northeastern Iranian Plateau: Insight from K-feldspar ⁴⁰ Ar/ ³⁹ Ar thermochronology from the Shotor Kuh–Biarjmand metamorphic core complex

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Geochronology and geochemistry of rhyolites from Hormuz Island, southern Iran: A new record of Cadomian arc magmatism in the Hormuz Formation

Cited by 59 publications

References 47 publications

Triple oxygen isotope variations in magnetite from iron-oxide deposits, central Iran, record magmatic fluid interaction with evaporite and carbonate host rocks

Triple oxygen isotope variations in magnetite from iron-oxide deposits, central Iran, record magmatic fluid interaction with evaporite and carbonate host rocks

Salt tectonics in a double salt‐source layer setting (Eastern Persian Gulf, Iran): Insights from interpretation of seismic profiles and sequential cross‐section restoration

Large-magnitude continental extension in the northeastern Iranian Plateau: Insight from K-feldspar 40 Ar/ 39 Ar thermochronology from the Shotor Kuh–Biarjmand metamorphic core complex

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Large-magnitude continental extension in the northeastern Iranian Plateau: Insight from K-feldspar ⁴⁰ Ar/ ³⁹ Ar thermochronology from the Shotor Kuh–Biarjmand metamorphic core complex