Birth, death, and resurrection: The life cycle of suprasubduction zone ophiolites

Abstract

[1] Abstract: Suprasubduction zone (SSZ) ophiolites display a consistent sequence of events during their formation and evolution that suggests that they form in response to processes that are common to all such ophiolites. This sequence includes the following: (1) birth, which entails the formation of the ophiolite above a nascent or reconfigured subduction zone; this stage is typically characterized by the eruption of arc tholeiite lavas and the formation of layered gabbros and sheeted dike complex; (2) youth, during which is continued melting of refractory asthenosphere (depleted during birth) occurs in response to fluid flux from the subducting slab, with extensional deformation of the older plutonic suite, eruption of refractory lavas, and the intrusion of wehrlite-pyroxenite; (3) maturity, with the onset of semistable arc volcanism, typically calc-alkaline, as the subduction zone matures and stabilizes, and the intrusion of quartz diorite and eruption of silicic lavas; and (4) death, which is the sudden demise of active spreading and ophiolite-related volcanism, which in many cases is linked to collision with an active spreading center and the onset of shallow underthrusting of the buoyant spreading axis; expressed as dikes and lavas with oceanic basalt compositions that crosscut or overlie rocks of the older suites; (5) resurrection, with emplacement by obduction onto a passive margin or accretionary uplift with continued subduction. The early stages (1± 3) may be diachronous, and each stage may overlap in both time and space. The existence of this consistent progression implies that ophiolite formation is not a stochastic event but is a natural consequence of the SSZ tectonic setting.

The tauride ophiolites of Anatolia (Turkey): A review

“…Fracture zones separating oceanic lithosphere of different ages and densities are the most plausible sites for subduction initiation (Stern and Bloomer, 1992;Casey and Dewey, 1984;Hawkins et al, 1984;Leitch, 1984). The initiation of subduction starts in response to convergence due to major plate re-organizations (Shervais, 2001;Casey and Dewey, 1984;Hawkins et al, 1984). Stern and Bloomer (1992) suggested that old dense lithosphere sinking into the asthenosphere rolls back and leaves a gap that is filled by rapid spreading at the leading edge of the lithosphere in the upper plate.…”

Insights on the kinematics of the India‐Eurasia collision from global geodynamic models

“…Light gray shading represents extent of Eurasian continental crust in our model. central NeoTethys [Hafkenscheid et al, 2006;Pearce et al, 1981;Shervais, 2001;Stampfli and Borel, 2002]. Cessation of arc-magmatism along the Kohistan-Ladakh arc at $61 Ma can be interpreted as the onset of ophiolite emplacement onto Greater India [Khan et al, 2009], while further east the Zedong Ophiolite was likely to have been emplaced at $57 Ma [Ali and Aitchison, 2008].…”

Geochemistry, petrology and tectonomagmatic significance of basaltic rocks from the ophiolite mélange at the NW External-Internal Dinarides junction (Croatia)

“…7B1) and at the same time show HFSE negative anomalies (Fig. 7A1) which are unique characteristics of MORBs with arc signatures (Shervais 2001). Surprisingly, although the LREE depletion in the medium-Ti basalts is more pronounced they display considerably higher relative depletion of Ta-Nb thus confronting MORB and SSZ signatures in one single geochemical group.…”

“…These composite blocks give strong evidence for the "stage of birth" from the geodynamic model of SSZ ophiolites proposed by Shervais (2001). Stern (2004) thought that such association of extrusive rocks were formed by extensive magmatism in the extensional proto-arc-fore-arc basin that spreads over the still active subducting ridge.…”