[1] Abstract: Peridotite xenoliths erupted in late Miocene basalts ( 8 Ma) in the central Sierra Nevada sample a lithosphere that is vertically stratified in terms of age and thermal history. The deeper portions ( 45–100 km) have asthenospheric osmium isotopic compositons and possess textural and chemical evidence for cooling from >11008 to 700–8208C. The shallower portions (<60 km) have unradi...

The trace element and Nd, Sr, and Pb isotopic compositions of extension-related late Cenozoic basalts in southern Nevada were determined in order to constrain models for the tectonic evolution of the subcrustal mantle in the southern Great Basin since 10 Ma. Basalts in southern Nevada between latitudes 36øN and 37øN have low ENd (--8 to -10), high A8/4 (+70 to + 107) and A7/4 (+8 to + 12), high...

*Correspondence: Paterno R. Castillo, Geosciences Research Division, Scripps Institution of Oceanography, University of California, San Diego, 8615 Kennel Way, La Jolla, CA 92037, USA e-mail: [email protected] †Present address: Sæmundur A. Halldórsson, Nordic Volcanological Center, Institute of Earth Sciences, University of Iceland, Reykjavik, Iceland The recently-discovered high, plume-like 3...

in taleghan, olivine basalt-basaltic andesite dykes as part of tertiary mamgmatic activities in central and western alborz zone, intruded into both karaj formation and late eocene-oligocene volcanic rocks. these dykes have similar geochemical characteristic which suggest that they are originated from a common source. on the primitive mantle normalized spider diagram, the dykes are characterized...

[1] We image the crustal architecture of the Musgrave Province with petrophysically constrained forward models of new potential field data. These models image divergent shallow-dipping crustal scale thrusts that, at depth, link with an axial zone defined by steeper, lithospheric scale transpressional shear zones. They also show that to permit a near-surface density distribution that is consiste...

Long-standing debates exist over the timing and mechanism of uplift of the Tibetan Plateau and, more specifically, over the connection between lithospheric evolution and surface expressions of plateau uplift and volcanism. Here we show a T-shaped high wave speed structure in our new tomographic model beneath South-Central Tibet, interpreted as an upper-mantle remnant from earlier lithospheric f...

S U M M A R Y A 3-D finite-element simulation of global electromagnetic induction is used to evaluate satellite responses in geomagnetic dipole coordinates for harmonic ring-current excitation of a threelayer mantle overlain by a realistic near-surface conductance distribution. Induced currents are modelled for lithospheric and asthenospheric upper-mantle conductivities in the range σ = 10−4–0....

We derive estimates of temperature of the Australian continental mantle between 80 and 350 km depth from two published S-velocity models. Lithospheric temperatures range over about 1000 8C, with a large-scale correlation between temperature and tectonic age. In detail however, variations ranging from 200 to 700 8C occur within each tectonic province. At the current seismic resolution, strictly ...

Tomograms of the upper mantle, which represent perturbations in P-wave, shear wave speed, and bulk-sound speed, image the Indo-Australian plate subducting beneath the Eurasian plate along the Sumatra–Andaman arc. The detailed images of the subducting slab are well constrained by the large number of intermediate depth earthquakes and moderate seismic station coverage along the entire Indonesian–...

Thermobarometric and Os isotopic data for peridotite xenoliths from late Miocene and younger lavas in the Sierra Nevada reveal that the lithospheric mantle is vertically stratified: the shallowest portions (<45 to 60 kilometers) are cold (670 degrees to 740 degrees C) and show evidence for heating and yield Proterozoic Os model ages, whereas the deeper portions (45 to 100 kilometers) yield Phan...