High‐Precision U‐Pb Zircon Dating of Late Magmatism in the Samail Ophiolite: A Record of Subduction Initiation

Abstract

The Samail (Oman-UAE) ophiolite is the largest and best studied ophiolite in the world, and observations from the ophiolite have had a major impact on models for the structure and petrogenetic history of fastspread oceanic lithosphere (e.g.,

The Origin of Felsic Intrusions Within the Mantle Section of the Samail Ophiolite: Geochemical Evidence for Three Distinct Mixing and Fractionation Trends

“…rocks related to V2 magmatism (Rioux et al, 2021). The data, therefore, suggest two distinct generations of felsic mantle intrusions, with an earlier set related to V2 magmatism and a later series linked to melting of underthrust amphibolite and metasediment.…”

“…We therefore consider it most likely that this felsic dike formed by extensive differentiation of magmas related to the V2 series within the uppermost mantle. Interestingly, there is an offset in dates between the LREE depleted dike (13217M01) and the four dated LREE enriched mantle dikes (Rioux et al, 2021) The 20% amphibolite melt was modeled using the parameters described in Figure 8, with 0% garnet. Data sources: felsic mantle dike REE (this study; Amri et al, 2007;Haase et al, 2015); amphibolite+sediment melt model (Rollinson, 2015); Lasail and Alley REE patterns (Godard et al, 2003;Godard et al, 2006).…”

“…The felsic dikes within the mantle section in the UAE are ∼0.9-4.0 Ma younger than the similar intrusions within the Oman section (Rioux et al, 2021). Cox et al (1999) used isotopic and geochemical data to argue that the UAE dikes range from pure metasediment partial melts to mixtures of metasediment and meta-basaltic partial melts.…”

“…In a companion study to this manuscript (Rioux et al, 2021), we present new high-precision U-Pb dating, which constrains the timing of dike intrusion relative to formation of the ophiolite crust, as well as age variations in the felsic mantle dikes along the length of the ophiolite. Our previous work has shown that gabbros related to the V1 volcanic series, the main phase of crustal growth in the ophiolite, yield zircon dates of 96.1-95.6 Ma (Rioux et al, 2012(Rioux et al, , 2016, indicating rapid crustal growth.…”

Geologically calibrated mammalian tree and the corresponding global events, including birth of human

“…The Euarchontoglires origin cannot be addressed by vicariance. Closure of the Tethys Sea was related to formative process of European Alps (apatite and zircon ssion track ages; exhumation around 15 Bertrand et al, 2017) and Himalayan Range by Indian collision (exhume episode; the South Tibetan Detachment System; around 20 Searl and Godin, 2003; gneissose and granitic domes in northern Vietnam;around 25 Ma;, and the Semail ophiolite (95 Ma including the age of metamorphic sole; Cowan et al, 2014;Rioux et al, 2021; Arabian Peninsula was a part of Africa; Zagros suture granitoid; U-Pb age: 37.7 ± 1.0 Rezaei et al, 2021) and the Troodos ophiolite (90, 75, 55 Ma;Osozawa et al, 2012b) also record the closure time, and these closing times may be related to the dispersal events of Afrotheria (or Euarchontoglires).…”