Subduction initiation of the Neo-Tethys Ocean in Central Iran based on U-Pb geochronology, geochemical and Nd isotope data of the Ashin ophiolite
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in: Ofioliti, Jahrgang 47.2022, Nr. 2, 29.07.2022, S. 155-171.
Publikationen: Beitrag in Fachzeitschrift › Artikel › Forschung › (peer-reviewed)
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T1 - Subduction initiation of the Neo-Tethys Ocean in Central Iran based on U-Pb geochronology, geochemical and Nd isotope data of the Ashin ophiolite
AU - Shirdashtzadeh, Nargess
AU - Furnes, Harald
AU - Miller, Nathaniel R.
AU - Dantas, Elton Luiz
AU - Torabi, Ghodrat
AU - Meisel, Thomas C.
N1 - Publisher Copyright: © 2022, Edizioni ETS. All rights reserved.
PY - 2022/7/29
Y1 - 2022/7/29
N2 - Subduction initiation (SI) ophiolites are critical for reconstructing plate tectonic and magmatic evolution along ancient convergent margins. Here we integrate clinopyroxene and whole rock chemical compositions, whole rock Nd isotopic compositions, and zircon U-Pb geochronology to demonstrate that the Ashin ophiolite between the Torbat-e-Heydarieh-Sabzevar and Nain-Baft ophiolitic Belts, records the initiation of late Early Cretaceous subduction magmatism and formation of Neo-Tethys oceanic crust. Clinopyroxene and whole rock geochemical compositions of Ashin non-metamorphosed pillow lavas and ortho-amphibolites (metamorphosed pillow lavas) and ortho-amphibolitic dikes (metamorphosed diabase dikes) and whole rock compositions of comparable ophiolite exposures from Nain, Dehshir, and Shahr-Babak areas support a basaltic protolith generated during a subduction initiation system. Based on geochemicaldata, Sm/Nd > 0.4, Lu/Hf > 0.3, CeN/YbN < 1.2, DyN/YbN < 1.2, GdN/YbN < 1, LaN/YbN < 1, Th/Nb < 0.2 ratios, and εNdI > +9 can characterize the forearc basalt (FAB) affinity of ophiolitic mafic rocks. Geochronological (~ 107-94 Ma radiolarian cherts) and geochemical characteristics of the Ashin pillow lavas reflect a MORB-like forearc basin formed during subduction initiation towards the end of the Early Cretaceous. Then a younger group of basic pillow lavas and dikes formed and metamorphosed (to the amphibolites and amphibolitic dikes) in MORB-like (before 104 Ma) to SSZ-like (~ 97 Ma) SI settings based on zircon U-Pb ages and geochemical data. This short-lived oceanic basin (~ 13 Myrs, from ~ 107 to 94 Ma) closed at around 60 Ma (in Paleocene).
AB - Subduction initiation (SI) ophiolites are critical for reconstructing plate tectonic and magmatic evolution along ancient convergent margins. Here we integrate clinopyroxene and whole rock chemical compositions, whole rock Nd isotopic compositions, and zircon U-Pb geochronology to demonstrate that the Ashin ophiolite between the Torbat-e-Heydarieh-Sabzevar and Nain-Baft ophiolitic Belts, records the initiation of late Early Cretaceous subduction magmatism and formation of Neo-Tethys oceanic crust. Clinopyroxene and whole rock geochemical compositions of Ashin non-metamorphosed pillow lavas and ortho-amphibolites (metamorphosed pillow lavas) and ortho-amphibolitic dikes (metamorphosed diabase dikes) and whole rock compositions of comparable ophiolite exposures from Nain, Dehshir, and Shahr-Babak areas support a basaltic protolith generated during a subduction initiation system. Based on geochemicaldata, Sm/Nd > 0.4, Lu/Hf > 0.3, CeN/YbN < 1.2, DyN/YbN < 1.2, GdN/YbN < 1, LaN/YbN < 1, Th/Nb < 0.2 ratios, and εNdI > +9 can characterize the forearc basalt (FAB) affinity of ophiolitic mafic rocks. Geochronological (~ 107-94 Ma radiolarian cherts) and geochemical characteristics of the Ashin pillow lavas reflect a MORB-like forearc basin formed during subduction initiation towards the end of the Early Cretaceous. Then a younger group of basic pillow lavas and dikes formed and metamorphosed (to the amphibolites and amphibolitic dikes) in MORB-like (before 104 Ma) to SSZ-like (~ 97 Ma) SI settings based on zircon U-Pb ages and geochemical data. This short-lived oceanic basin (~ 13 Myrs, from ~ 107 to 94 Ma) closed at around 60 Ma (in Paleocene).
KW - Ashin Ophiolite
KW - Iran
KW - Neo-Tethys Ocean
KW - subduction initiation
UR - http://www.scopus.com/inward/record.url?scp=85135140644&partnerID=8YFLogxK
U2 - 10.4454/ofioliti.v47i2.557
DO - 10.4454/ofioliti.v47i2.557
M3 - Article
AN - SCOPUS:85135140644
VL - 47.2022
SP - 155
EP - 171
JO - Ofioliti
JF - Ofioliti
SN - 0391-2612
IS - 2
ER -