a r t i c l e i n f o Keywords: East Pacific Rise mid-ocean ridge oceanic crust off-axis magmatism waveform modeling Formation of oceanic crust along the East Pacific Rise is thought to be complete within a few kilometers of the rise axis. Here, however, we present evidence for magmatism 20 km from the spreading center in 300-ka-old crust. Seismic data reveal an intrusive complex ~ 2 km beneath...

Slab breakoff is the buoyancy-driven detachment of subducted oceanic lithosphere from the light continental lithosphere that follows it during continental collision. In a recent paper Davies and von Blanckenburg [1994] have assessed the physical conditions leading to breakoff by quantitative thermomechanical modeling and have predicted various consequences in the evolution of mountain belts. Br...

Magraatism and volcanism exhibit spatial and temporal clustering on a wide range of scales. Using the spatial pair-correlation function, the number of pairs of magmatic orvolcanic events whose separation is between r« Ar and r + « Ar per unit area, we quantify the spatial clustering of raagraatism and volcanism in several data sets. Statistically self-similar clustering characterized by power l...

The frequent formation of large igneous provinces during the opening of the Atlantic Ocean is a surface manifestation of the thermal and chemical state of convecting mantle beneath the supercontinent Pangea. Recent geochemical and geophysical findings from the North Atlantic igneous province all point to the significant role of incomplete mantle mixing in igneous petrogenesis. On the basis of a...

the halak abad prospect occurs in the northeastern part of central iran zone (sabzevar structural zone). in this investigation, geochemical evolution, age and source of part of northeastern iran magmatic arc (intrusive bodies) in halak abad area in the khorasan razavi province has been studied. the exposed rocks consist of volcanic rocks with andesite and dacite nature, limestone, plutonic rock...

A Late Cretaceous (92 to 86 million years ago) vertebrate assemblage from the high Canadian Arctic (Axel Heiberg Island) implies that polar climates were warm (mean annual temperature exceeding 14 degreesC) rather than near freezing. The assemblage includes large (2.4 meters long) champsosaurs, which are extinct crocodilelike reptiles. Magmatism at six large igneous provinces at this time sugge...

Introduction: Angrites are basaltic meteorites that cooled rapidly early in the evolution of the solar system [1]. They are widely thought to be products of differentiation and partial melting [2-4], though it has been suggested that they condensed from vapor in the solar nebula [5,6]. D’Orbigny (“D’O”) is vesicular and has abundant glass [2,5-7]. This has been interpreted as volcanic and seen ...

Introduction: The lower crust of the Moon remains a critical unknown for models of lunar compositional mass balance and for models of petrogenesis of lunar rock types. Key questions addressed here are (1) how mafic are the rocks of the lower crust and (2) are they ferroan or magnesian? Answers to these questions bear on the concentration and distribution of radiogenic heat-producing elements an...