chaldoran area in nw of iran has mesozoic oceanic crust basement. the studied rocks of this region can be divided into three groups: ophiolitic gabbros and pillow lavas, ophiolitic volcanoclastics and eocene lava flows. ophiolitic mafic rocks show continental volcanic arc natures and eocene lava flow shows oib-like nature. during the mesozoic,the chaldoran region was situated in the active cont...

[1] The Tonga-Kermadec subduction system in the southwest Pacific preserves a series of crustal elements and sediments which have recorded subduction initiation, rift, and back-arc basin formation. The Norfolk Basin is the farthest landward of all back-arc basins formed in the Tonga-Kermadec region and may preserve the earliest record of subduction initiation regionally. For the Norfolk Basin, ...

[1] We present major, volatile, and trace elements for quenched glasses from the Fonualei Spreading Center, a nascent spreading system situated very close to the Tofua Volcanic Arc (20 km at the closest), in the northeast Lau Basin. The glasses are basalts and basaltic andesites and are inferred to have originated from a relatively hot and depleted mantle wedge. The Fonualei Spreading Center sh...

The Nam Pat Group of the Nam Pat Basin, Uttaradit Province, Thailand is situated in the Nan Suture Zone. Two contrasting tectonic framework models of the Nan Suture have previously been proposed: as a main Paleo-Tethyan suture and as a remnant of a closed back-arc basin. The goal of this study is to analyze the tectonic framework of the Nan Suture and reevaluate the existing tectonic models. Th...

It has been suggested that post-orogenic lithospheric removal in continental back arcs promotes extension and surface subsidence. However, the surface response of this process and its primary difference from “classical” back-arc opening have remained uncertain. Here, the back-arc extension process with varying continental mantle lithosphere thickness and thermal heterogeneities is studied by us...

The Ophiolite Terrane of the Southern Chewore Inliers is comprised of two related, but lithologicallyand geochemically-distinct groups. The Maunde Ophiolite Group comprises a suite of lithologies similar to those within Phanerozoic ophiolites. The Kaourera Island Arc Group contains a suite of silica-variable, extrusive lithologies similar to those within present-day island-arcs. Geochemical ana...

Late Miocene (7–9 Ma) basaltic rocks from the Monbetsu-Kamishihoro graben in northeast Hokkaido have chemical affinities to certain back-arc basin basalts (referred to herein as Hokkaido BABB). Pb-, Ndand Sr-isotopic compositions of the Hokkaido BABB and arc-type volcanic rocks (11–13 Ma and 4–4.5 Ma) from the nearby region indicate mixing between the depleted mantle and an EM II-like enriched ...

[1] Subduction zone magmas are characterized by high concentrations of H2O, presumably derived from the subducted plate and ultimately responsible for melting at this tectonic setting. Previous studies of the role of water during mantle melting beneath back-arc basins found positive correlations between the H2O concentration of the mantle (H2Oo) and the extent of melting (F), in contrast to the...