Dating continental subduction beneath the Samail Ophiolite: garnet, zircon, and rutile petrochronology of the As Sifah eclogites, NE Oman

Garber, Joshua M.; Rioux, Matthew; Searle, Mike; Kylander‐Clark, Andrew; Hacker, Bradley R.; Vervoort, Jeff D.; Warren, Clare J.; Smye, Andrew J.

doi:10.1002/essoar.10507466.1

Cited by 3 publications

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“…The Semail ophiolite was obducted onto the northeastern margin of the Arabian plate, along with the allochthonous thrust sheets beneath (Coleman, 1981; Glennie et al., 1973, 1974; Searle, 2007). The initial oceanic subduction of Tethyan oceanic crust below the Semail ophiolite occurred at about 96‐95 Ma from U‐Pb zircon dating of metamorphic sole amphibolites accreted along the base of ophiolite (Rioux et al., 2016) and the ensuing continental margin subduction reached its peak high‐pressure metamorphism at about 81‐77 Ma (Garber et al., 2021; Warren et al., 2003). The obduction of the Semail ophiolite resulted in south‐westward thrusting of the accreted slope (Sumeini complex) and deep‐marine Hawasina thrust sheets over the Arabian margin (Callot et al., 2017; Tarapoanca et al., 2013).…”

Section: Discussionmentioning

confidence: 99%

Tectono‐Stratigraphic Evolution of the Foreland Fold‐and‐Thrust Belt of the United Arab Emirates

2022

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The subsurface and surface structural geometries of the United Arab Emirates (UAE) fold‐and‐thrust belt (FTB) and foreland basins are interpreted from seismic, well data, and surface geology. Twelve horizons ranging in age from Miocene to Lower Jurassic were interpreted and mapped. Additionally, we outlined subsurface extent of Sumeini and Hawasina allochthonous nappes. The tectonic subsidence curves suggest that the final major passive margin rifting event occurred in the early Aalenian and lasted till Oxfordian. Loading of the Semail ophiolite thrust sheet and accompanying allochthonous thrust sheets resulted in uplift at ca. 95 Ma and rapid subsidence at ca. 83 Ma, indicating the transition of the Arabian margin from a rifted passive margin to a foreland basin. The region witnessed an accelerated subsidence during the late Oligocene‐Miocene, attributed to the initial collision of the Central Iran and Arabian plates. The Permian‐Jurassic NW‐SE oriented rift faults were reactivated as thrust faults during the Late Cretaceous ophiolite obduction and late Oligocene‐Miocene continental collision. Two different tectonic regimes are identified in the FTB. The northern regime is characterized by major inversion of the rift faults with up to 3,700 m throw, whereas the southern regime has a major pop‐up structure with possible basement origin. Four major west‐verging and east‐dipping thrusts, which cross the northern area, form fault‐propagation folds and dissect the entire stratigraphy. Moreover, the Hawasina décollement, together with the inverted basement structures formed the Jabal Hafit anticline as a backthrust structure.

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Section: Discussionmentioning

confidence: 99%

Tectono‐Stratigraphic Evolution of the Foreland Fold‐and‐Thrust Belt of the United Arab Emirates

2022

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“…Leng and Gurnis (2011) proposed that slab sinking causes a strong influx of asthenosphere above the foundering slab (Figure 6d). This rollback must have followed initial melting of the sole by 100 Ma (Garber et al., 2021) and subsequently caused fast spreading forming the Samail Ophiolite at 96‐94 Ma. Rollback probably aided the clockwise rotation of the Samail subduction zone as indicated by paleomagnetic data (Morris et al., 2016; van Hinsbergen et al., 2019).…”

Section: Discussionmentioning

confidence: 99%

“…Garber et al. (2021) reported three Sm‐Nd garnet‐whole‐rock ages between 81 ± 1 and 78 ± 2 Ma. Because the garnets have typical growth zonation, the latter ages reflect a prograde‐to‐peak HP stage.…”

Section: Settingmentioning

confidence: 99%

“…(2021)). Prograde to peak HP metamorphism of the As Sifah Unit occurred between 81 and 76 Ma (El‐Shazly et al., 2001; Garber et al., 2021; Warren et al., 2003, 2005). Most workers make the simplifying assumption that ages of 81‐76 Ma date HP metamorphism across the entire Saih Hatat window (e.g., Agard et al., 2010; Garber et al., 2020; Hansman et al., 2021).…”

Section: Introductionmentioning

confidence: 99%

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Some Like It Cold: The “Conundrum of Samail” Revisited

et al. 2023

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The "conundrum of Samail" (Hacker & Gnos, 1997) refers to the interaction of "hot" processes of subduction initiation with "cold" high-pressure (HP) metamorphism in the Oman Mountains. Hacker and Gnos (1997) discussed the example of the far-traveled, non-HP Samail Ophiolite and its underlying high-temperature (HT) metamorphic sole that formed above an infant, hot, intraoceanic subduction zone and overlies the cold, continental Saih Hatat HP complex that originated in a mature subduction setting (Figures 1 and 2).The onset of intraoceanic subduction is associated with the formation of a metamorphic sole (i.e., HT rocks subsequently welded to the base of the suprasubduction-zone ophiolite) reflecting elevated, transient thermal gradients (e.g., Dewey & Bird, 1971;Stern & Bloomer, 1992), which in the intraoceanic Samail subduction zone at the northeastern Arabian margin in Oman were up to ∼30°C km −1 (e.g., Garber et al., 2020;Searle & Cox, 2002). The available age data constraining high-grade metamorphism and partial melting of the metamorphic sole and subsequent formation of the Samail Ophiolite (Garber et al., 2020;Guilmette et al., 2018;Rioux et al., 2021;Soret et al., 2022) demonstrate hot subduction-zone processes between 105 and 93 Ma (Figure 3). Compiled data from 70 subduction zones by Lallemand and Arcay (2021) and numerical modeling by Peacock (1990) indicate that it takes 5-15 Ma between hot subduction-zone initiation and self-sustained, steady-state subduction characterized by a stable, low-thermal gradient of ∼10°C km −1 .The almost completely exposed Saih Hatat window (Figure 2) represents a formidable example of a HP complex and provides a one-of-a-kind natural laboratory important for understanding subduction-zone processes. A shortcoming of the Saih Hatat HP rocks is its controversial and incomplete geochronology. Almost all geochronologic

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Progressive veining during peridotite carbonation: insights from listvenites in Hole BT1B, Samail ophiolite (Oman)

et al. 2022

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Abstract. The reaction of serpentinized peridotite with CO2-bearing fluids to form listvenite (quartz–carbonate rock) requires massive fluid flux and significant permeability despite an increase in solid volume. Listvenite and serpentinite samples from Hole BT1B of the Oman Drilling Project help to understand mechanisms and feedbacks during vein formation in this process. Samples analyzed in this study contain abundant magnesite veins in closely spaced, parallel sets and younger quartz-rich veins. Cross-cutting relationships suggest that antitaxial, zoned magnesite veins with elongated grains growing from a median zone towards the wall rock are among the earliest structures to form during carbonation of serpentinite. Their bisymmetric chemical zoning of variable Ca and Fe contents, a systematic distribution of SiO2 and Fe-oxide inclusions in these zones, and cross-cutting relations with Fe oxides and Cr spinel indicate that they record progress of reaction fronts during replacement of serpentine by carbonate in addition to dilatant vein growth. Euhedral terminations and growth textures of magnesite vein fill, together with local dolomite precipitation and voids along the vein–wall rock interface, suggest that these veins acted as preferred fluid pathways allowing infiltration of CO2-rich fluids necessary for carbonation to progress. Fracturing and fluid flow were probably further enabled by external tectonic stress, as indicated by closely spaced sets of subparallel carbonate veins. Despite widespread subsequent quartz mineralization in the rock matrix and veins, which most likely caused a reduction in the permeability network, carbonation proceeded to completion within listvenite horizons.

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Dating continental subduction beneath the Samail Ophiolite: garnet, zircon, and rutile petrochronology of the As Sifah eclogites, NE Oman

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Cited by 3 publications

References 90 publications

Tectono‐Stratigraphic Evolution of the Foreland Fold‐and‐Thrust Belt of the United Arab Emirates

Tectono‐Stratigraphic Evolution of the Foreland Fold‐and‐Thrust Belt of the United Arab Emirates

Some Like It Cold: The “Conundrum of Samail” Revisited

Progressive veining during peridotite carbonation: insights from listvenites in Hole BT1B, Samail ophiolite (Oman)

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