Supra‐Subduction Zone Ophiolite Formed in an Extensional Forearc: Trinity Terrane, Klamath Mountains, California

Wallin, E. Timothy; Metcalf, Rodney V.

doi:10.1086/516044

Cited by 95 publications

(60 citation statements)

References 2 publications

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“…The elevated concentrations of LILE relative to HFSE in subduction zone magmas originate from fluids derived from the subducting slab. These slab-derived fluids carry high concentrations of LILE while the HFSE, most notably Nb, are retained in the slab (Arculus & Powell, 1986;Pearce, 1982;Wallin & Metcalf, 1998;Yogodzinski, Volynets, Koloskov, Seliverstov, & Matvenkov, 1993). Therefore the negative Nb anomaly is clearly intrinsic to the parental magma of the isolated dykes.…”

Section: Methodsmentioning

confidence: 97%

Geochemical characteristics of ophiolitic rocks from the southern margin of the Sivas basin and their implications for the Inner Tauride Ocean, Central-Eastern Turkey

2017

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Number of dismembered ophiolite bodies crop out between Sivas and Malatya on the top of the Eastern Tauride platform in the central-eastern Turkey. One of which at the southern margin of the Sivas basin in the Tecer Mountain area comprises melange and the lower part of an oceanic lithospheric section on top of the Tauride platform. The mantle tectonites are characterized by variably serpentinized harzburgites and dunites, and are intruded by numerous isolated dykes. The gabbroic cumulates consist of olivine gabbro, gabbro and gabbronorite. The major and trace element geochemistry of the mafic cumulate rocks suggests that the primary magma was compositionally similar to those observed in modern island-arc tholeiitic sequences. The isolated dykes are exclusively basaltic in composition and display geochemically two distinct subgroups: Group I is represented by high TiO 2 (.87-1.47 wt.%) and other incompatible elements, whereas Group II is characterized by low TiO 2 (.36-.66 wt.%) and other incompatible elements. The Group I isolated diabase dykes have flat to slightly LREE-depleted profiles (La/Yb N = .32-.79), whereas the Group II isolated diabase dykes are more depleted in general and have a LREEdepleted character (La/Yb N = .19-.49). This suggests that the isolated dykes were derived from an island arc tholeiitic magma (Nb/Y = .02-.05) with different degrees of partial melting (Group II > Group I) and relatively high oxygen fugacity in intra-oceanic subduction zone. The ophiolitic rocks in the study area may well be compared with the Divriği ophiolite to the southeast. All the evidence suggests that the isolated dykes in the Tecer Mountain area differ from the alkaline isolated dykes cutting the Divriği ophiolite. Since the late stage dykes (~76 Ma) in the Divriği area are alkaline, the tholeiitic isolated dykes in the present study should have been emplaced prior to the alkaline dykes during Late Cretaceous SSZ-spreading (~90 Ma) within the Inner Tauride Ocean.

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Section: Methodsmentioning

confidence: 97%

Geochemical characteristics of ophiolitic rocks from the southern margin of the Sivas basin and their implications for the Inner Tauride Ocean, Central-Eastern Turkey

2017

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“…Klamath terranes contain abundant mafic igneous rocks, fine-grained clastic strata, and chert-argillite-limestone units containing Tethyan fauna, deposited on a structurally-dismembered maficultramafic basement. Individual terranes were stranded by a component of east-descending underflow during mid-Paleozoic to mid-Mesozoic time (Irwin, 1981;Hacker et al, 1993Hacker et al, , 1995Wallin and Metcalf, 1998). Coeval intermediate and felsic igneous units are rare, whereas postkinematic, Late Jurassic and Early Cretaceous granitic stocks intruded the imbricated orogen (Lanphere et al, 1968;Irwin and Wooden, 1999).…”

Section: Central and Southern Klamath Mountainsmentioning

confidence: 99%

Mesozoic transpression, transtension, subduction and metallogenesis in northern and central California

2008

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Middle Paleozoic to Middle Jurassic terrane assemblies in the Klamaths and Sierran Foothills consist of mafic-ultramafic complexes + fine-grained terrigenous strata derived from previously accreted continental-margin belts. Sutured oceanic terranes reflect c. 230 Myr of margin-parallel slip involving chiefly transtension and transpression. Quartzofeldspathic clastic rocks and blueschists ± eclogites are very rare. Little devolatilization occurred at magmagenic depths; hence, coeval hydrothermal ore deposits and granitoids are uncommon. In contrast, nearly head-on Cretaceous subduction of the Farallon plate generated the massive Klamath-Sierra Nevada volcanicplutonic arc, reflecting dewatering of the eastward descending oceanic lithosphere in the magmagenic zone. Immature Great Valley forearc and Franciscan trench deposits shed from the arc record c. 70 Myr. of rapid crustal growth. Au-bearing solutions rising from magmagenic depths, exsolved from plutons, and expelled from heated wall rocks were mobilized attending arc construction. Precipitation of gold-bearing quartz veins

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“…Th within the LIL element group is relatively stable and reliable indicator, whose enrichment relative to other incompatible elements is taken to represent the subduction zone component (Wood et al 1979;Pearce 1983). Moreover, the negative Nb anomaly may indicate a subduction-related tectonic setting for the Group I isolated dikes (Arculus and Powel 1986;Yogodzinski et al 1993;Wallin and Metcalf 1998). Whereas, the Group II isolated dikes differ from the Group I isolated dikes in terms of REE and multi-element patterns (Fig.…”

Section: Geochemistrymentioning

confidence: 98%

Petrology of the Tekirova (Antalya) ophiolite (Southern Turkey): evidence for diverse magma generations and their tectonic implications during Neotethyan-subduction

Bağci

Parlak

2007

Int J Earth Sci (Geol Rundsch)

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The SW Antalya Complex is an assemblage of Mesozoic carbonate platform, margin and ophiolitic rocks which record the formation and tectonic emplacement of a small Mesozoic ocean basin. The late Cretaceous ophiolitic rocks are located at two localities, namely the relatively intact Tekirova ophiolite to the east of Kemer zone and the dismembered Gödene ophiolite to the west of Kemer zone. The Tekirova (Antalya) ophiolite comprises harzburgitic tectonites, ultramafic to mafic cumulates, isotropic gabbros and sheeted dikes. Numerous isolated dikes, ranging in thickness from 5 cm to 10 m, intruded the crustal rocks at different structural levels. The isotropic gabbros are represented by gabbro, diorite and quartz diorite rocks with granular to ophitic-subophitic textures. The isolated dikes are characterized by dolerite, diabase and microdiorite with ophitic, intersertal and microgranular textures. These rocks exhibit tholeiitic to alkaline compositions. New geochemical data presented in this paper from the isolated dikes and isotropic gabbros suggest that there are three main types of parental basic magmas that form the oceanic crustal rocks of the Tekirova (Antalya) ophiolite. These are (1) IAT series which can be referred to the Group I isolated dikes and isotropic gabbros; (2) low-Ti boninitic series characterized by the Group II isolated dike and isotropic gabbros; and (3) OIB-type including the Group III isotropic gabbros. The geochemical evidence suggests that the crustal rocks of the Tekirova (Antalya) ophiolite were generated from a progressive source depletion from island arc tholeiites (IAT) to boninites. Therefore, a fore-arc tectonic setting seems likely for the generation of the crustal rocks from the Tekirova (Antalya) ophiolite in the southern branch of Neotethys during the Late Cretaceous. The OIB-type alkaline isotropic gabbros are thought to have resulted from either (1) a late-stage magmatic activity fed by melts that originated within an asthenospheric window due to slab break-off or (2) subduction of a ridge system which generated OIB source across the asthenospheric window that has been no influence of fluids from the subducted slab into the overlying mantle wedge, shortly before the emplacement of the Tekirova (Antalya) ophiolite onto the Tauride platform.

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Supra‐Subduction Zone Ophiolite Formed in an Extensional Forearc: Trinity Terrane, Klamath Mountains, California

Cited by 95 publications

References 2 publications

Geochemical characteristics of ophiolitic rocks from the southern margin of the Sivas basin and their implications for the Inner Tauride Ocean, Central-Eastern Turkey

Geochemical characteristics of ophiolitic rocks from the southern margin of the Sivas basin and their implications for the Inner Tauride Ocean, Central-Eastern Turkey

Mesozoic transpression, transtension, subduction and metallogenesis in northern and central California

Petrology of the Tekirova (Antalya) ophiolite (Southern Turkey): evidence for diverse magma generations and their tectonic implications during Neotethyan-subduction

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