[1] Documenting the mass flux through convergent plate margins is important to the understanding of petrogenesis in arc settings and to the origin of the continental crust, since subduction zones are the only major routes by which material extracted from the mantle can be returned to great depths within the Earth. Despite their significance, there has been a tendency to view subduction zones as...

a r t i c l e i n f o Crust extracted from the mantle in arcs is refined into continental crust in subduction zones. During sediment subduction, subduction erosion, arc subduction, and continent subduction, mafic rocks become eclogite and may sink into the mantle, whereas more silica-rich rocks are transformed into felsic gneisses that are less dense than peridotite but more dense than the uppe...

It is generally accepted that continental subduction and crustal exhumation play an important role in the evolution of many orogenic belts. A variety of geological evidence suggests that continental crust is occasionally subducted to depths of tens to perhaps 150 km (e.g. Chopin, 1984; Dewey et al., 1993; Matte et al., 1997). Recently, a series of simulations (Chemenda, 1993; Chemenda et al., 1...

a r t i c l e i n f o Keywords: Lithium isotopes A-type granite Mafic enclave Continental crust Lithium concentrations and isotopic compositions of 39 A-type granites and mafic enclaves from 11 plutons in Northeast China and the North China craton are used to constrain their genesis and to characterize further the average composition of the continental crust. Lithium concentrations (2.8 to 80 p...

The boundary between the crust and the mantle was discovered by Mohorovicic in 1909 under the European continent. Subsquent research in this century established the major differences between the continental and oceanic crust; a typical thickness for the continental crust is 30-50 km while a typical thickness for me oceanic crusts is 6 km. In terms of history the continental crust contains a muc...

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...

the study area is located south of ghonabad in eastern iran. this area is situated between two major faults, darouneh to the north and dashtbyaz to the south. the movements of these faults cased major dislocation of this block. najmabad granodiorite to granite batholith is elongated trending east-west 2×8 km2. mineralization is associated with granite and monzonite. alteration zones are: propyl...

Figure 1. Schematic cross sections through (A) Galicia Margin west of Iberian Peninsula (Boillot et al., 1995) and (B) Jurassic margin of Apulian continent toward Alpine Tethys (Manatschal and Bernoulli, 1999). Inset in B displays present location of margin in Swiss Alps and paleoposition of section in Jurassic time. Abbreviations in A: lcc—lower continental crust; man— mantle; S—S-reflector; s...

The magmatic activity (0-16 Ma) in Iceland is linked to a deep mantle plume that has been active for the past 62 My. Icelandic and northeast Atlantic basalts contain variable proportions of two enriched components, interpreted as recycled oceanic crust supplied by the plume, and subcontinental lithospheric mantle derived from the nearby continental margins. A restricted area in southeast Icelan...