Suprasubduction Zone Origin of the Pozanti-Karsanti Ophiolite (Southern Turkey) Deduced from Whole-rock and Mineral Chemistry of the Gabbroic Cumulates

Abstract

The Pozanti-Karsanti Ophiolite Complex is situated in the eastern Tauride Belt and represents a remnant of the Mesozoic Neotethyan Ocean. It consists of three distinct nappes: (1) an ophiolitic mélange; (2) a metamorphic sole; and (3) ophiolitic rocks. The oceanic lithosphere section of the Pozanti-Karsanti Ophiolite comprises mantle tectonites, ultramafic-mafic cumulates, isotropic gabbros, sheeted dykes and basaltic volcanic rocks. These units are cut by isolated microgabbro-diabase dykes at all structural levels. New results are presented on the whole-rock and mineral chemistry of the gabbroic cumulates. Well-layered, low-Ti gabbroic cumulates, showing adcumulate to mesocumulate textures, are represented exclusively by gabbronorites. The mineral chemistry of gabbronorites from the Pozanti-Karsanti Ophiolite indicates that these cumulate rocks have been produced by the low-pressure crystal fractionation of basaltic liquid. Magnesium numbers (Mg-numbers) of clinopyroxene, orthopyroxene and amphibole range from 89 to 73, 80–66 and 80–72, respectively. Plagioclase compositions range from An94 to An84. The coexistence of calcic plagioclase, magnesian clinopyroxene and orthopyroxene indicates that the cumulate gabbronorites from the Pozanti-Karsanti Ophiolite were formed in an arc environment. The covariation of Al2O3 and Mg-numbers of both clinopyroxene and orthopyroxene show features typical of low-pressure igneous intrusions such as the Skaergaard and Tonsina Complexes, but differ from the high-pressure ultramafic cumulates found in the same arc. The cumulate gabbronorites probably represent shallower levels in the arc which were subsequently juxtaposed against deeper level ultramafic cumulates either during accretion or later faulting.

Hydrothermal Alteration in the Main Sulfide Zone at Unki Mine, Shurugwi Subchamber of the Great Dyke, Zimbabwe: Evidence from Petrography and Silicates Mineral Chemistry

“…The Pozanti-Karsanti ophiolite has amphiboles ranging in composition from magnesiohornblende to actinolite [82] (Figure 18a). The aluminous amphiboles are thought have formed during high pressure, high temperature hydrothermal alteration [82].…”

“…The aluminous amphiboles are thought have formed during high pressure, high temperature hydrothermal alteration [82]. In this ophiolite, calcic amphiboles such as actinolite commonly occur rimming clinopyroxenes or high-Al and high-Fe hornblende [82].…”

“…The aluminous amphiboles are thought have formed during high pressure, high temperature hydrothermal alteration [82]. In this ophiolite, calcic amphiboles such as actinolite commonly occur rimming clinopyroxenes or high-Al and high-Fe hornblende [82]. Further, Stakes and Taylor (1992) [83] suggested that high-temperature metamorphic hornblendes in the Semail ophiolite of Oman (pargasites and edenites; [84]) were replaced by low-temperature actinolitic hornblendes due to the extensive moderate to low-temperature hydrothermal alteration.…”

“…(b) Figure 18. (a) Calcic amphiboles from the present study compared those from other intrusions and settings: Stillwater Complex primary hornblende [85], Merensky Reef of the Bushveld Complex [7,75], Mann Complex [73], Somerset intrusion [86], McIntosh intrusion [87], Duke Island complex, Alaska [88], and Pozanti-Karsanti ophiolite [82]. Unlike primary hornblende from the Stillwater Complex, calcic amphiboles from the MSZ at Unki Mine show a wide range in Si apfu consistent with hydrothermal alteration such as those in ophiolite complexes such as the Pozanti-Karsanti.…”

The tauride ophiolites of Anatolia (Turkey): A review

“…In the Köyceğiz (Muğla) region, a tectonic contact between the metamorphic sole and mantle tectonites is intruded by a post-metamorphic diabase dyke (Figs. 5a,5b Parlak et al, 2013Çelik, 2008;Parlak and Robertson, 2004;Parlak andDelaloye, 1999, 1996;Dilek et al, 1999 Alihoca (Bolkardağ) Saka et al, 2014;Parlak et al, 2013Parlak et al, , 2002Parlak et al, , 2000Çelik, 2007;Dilek et al, 1999;Lytwyn and Casey, 1995 Pınarbaşı ( Parlak et al, 2013Parlak et al, , 2006Parlak et al, , 2005 Cr#=100×Cr/(Cr+Al); IAT. Island arc tholeiite; WPA.…”