The petrogenesis and tectonic setting of lavas from the Baft Ophiolitic Mélange, southwest of Kerman, Iran

Abstract

A Late Cretaceous ophiolite complex in the Baft area, southwest of Kerman, Iran, is characteristic of the Central Iranian Ophiolitic Mélange Belt, which wraps around the Lut Block. Despite the extensive tectonic disruption of the Baft complex, most ophiolitic lithologies are present and many original igneous contacts are preserved. A lack of cumulate gabbros within the sequence suggests that a large and continuous magma chamber did not exist beneath the Baft spreading axis. Geochemical data confirm the presence of two distinct compositional groups in the mafic lavas: (1) tholeiitic basalt and (2) transitional tholeiitic basalt. The tholeiitic lavas are similar to typical mid-ocean-ridge basalt compositions, whereas the transitional tholeiites are similar to intraplate basalts. The available data suggest that the Baft ophiolite complex formed in a small ocean basin, possibly at or near a ridge–transform intersection. Emplacement may have occurred as a result of conversion of the transform fault to a subduction zone during a change in relative plate motion. A ridge–transform setting is compatible with the intraplate character of some of the transitional basalts, which probably represent off-axis (seamount) magmatism, marked by the absence of cumulate gabbros and the presence of a serpentinite mélange cut by basaltic dykes. The ridge–transform model suggests formation of the ophiolite in a narrow ocean basin separating the Sanandaj-Sirjan microcontinent from the Central Iran Block in Late Cretaceous time.

Geodynamic evolution of Upper Cretaceous Zagros ophiolites: formation of oceanic lithosphere above a nascent subduction zone

“…E-MORB-type pillow lavas were first reported by Arvin & Robinson (1994) in the Balvard-Baft ophiolite. Pillow lavas at the base of the ophiolite volcanic sequence are LREE enriched (La N /Yb N ∼ 5-6), lack Nb depletion (Nb/La ∼ 1.4 × N-MORB) and are similar to E-MORB.…”

“…Davoudzadeh, 1972;Stocklin, Eftekhar-Nezhad & Hushmandzadeh, 1972;Berberian & King, 1981;Arvin & Robinson, 1994;Arvin & Shokri, 1996). In many interpretations the Nain-Baft ophiolite belt represents a suture on the site of a small Mesozoic ocean basin (e.g.…”

Tectonic evolution of the Zagros Orogen in the realm of the Neotethys between the Central Iran and Arabian Plates: An ophiolite perspective

“…The Baft Ophiolite mantle sequence includes serpentinized and foliated harzburgite with patches of chromitite and minor lherzolite with diabasic dikes ( (Alavi 1994;Arvin and Robinson 1994). Based on lithostratigraphic relationships, the Baft Ophiolite was formed during the Cretaceous and was emplaced before the Paleocene (Lippard et al 1986; Shafaii Moghadam and Stern 2011).…”

Magma storage and plumbing of adakite-type post-ophiolite intrusions in the Sabzevar ophiolitic zone, northeast Iran

“…Neotethyan subduction gave rise to the Jurassic-Cretaceous Sanandaj-Sirjan subduction zone, trending parallel to the main Zagros thrust, as well as several back-arc oceanic seaways in central Iran (Omrani et al, 2008;Shafaii Moghadam et al, 2009;Rossetti et al, 2010). These back-arc oceanic domains (Sabzevar, Nain-Baft and Sistan) are thought to have opened during the Cretaceous period and closed during the transition from Paleocene to Eocene (Baroz et al, 1983;Arvin and Robinson, 1994;Shojaat et al, 2003;Babazadeh and de Wever, 2004). Iranian ophiolites as part of the Neotethyan oceanic region are the results of obduction processes of these minor oceanic seaways, showing discontinuous back-arc oceanic crust emplacement (Agard et al, 2011 and references therein).…”