A simple model which relates the rate of seafloor creation and the age of the oceanic lithosphere at subduction to the rate of continental accretion can successfully explain the apparent differences between Archaean and Phanerozoic terrains in terms of plate tectonics. The model has been derived using the following parameters: (1) the spreading rate at mid-ocean ridges; (2) the age of the ocean...

"Lithosphere" is a mechanical concept implying strength and relative permanence. Unfortunately, the term has also been applied to the surface thermal boundary layer (TBL) and a shallow enriched geochemical reservoir, features having nothing to do with strength. The "strong" lithosphere is about one half the thickness of the TBL. The bottom of the elastic plate, the maximum depths of midplate an...

[1] Oceanic lithosphere undergoes permanent deformation during subduction once the stresses exceed the elastic limit. Departures from elastic behavior occur by brittle failure in the shallow lithosphere and by a combination of lowand high-temperature creep at greater depths. We combine laboratory-based rheological models with estimates of slab shape from earthquake hypocenters to quantify the b...

During the roughly year-long Seismic Wave Exploration in the Lower Lithosphere (SWELL) pilot experiment in 1997/1998, eight ocean bottom instruments deployed to the southwest of the Hawaiian Islands recorded teleseismic Rayleigh waves with periods between 15 and 70 s. Such data are capable of resolving structural variations in the oceanic lithosphere and upper asthenosphere and therefore help u...

W e consider a series of simple calculations with a step-function change in thickness of the lithosphere and imposed, far-field boundary conditions to illustrate the influence of the lithosphere on mantle flow. We consider the effect of aspect ratio and far-field boundary conditions on the small-scale flow driven by a discontinuity in the thickness of the lithosphere. In an isothermal mantle, w...

The temporal coincidence between large igneous provinces (LIPs) and mass extinctions has led many to pose a causal relationship between the two. However, there is still no consensus on a mechanistic model that explains how magmatism leads to the turnover of terrestrial and marine plants, invertebrates and vertebrates. Here we present a synthesis of ammonite biostratigraphy, isotopic data and hi...

[1] Broadband seismic experiments over the last two decades have produced dense data coverage across Tibet. Yet, the mechanism of the India-Asia lithospheric convergence beneath it remains a puzzle, with even its basic features debated and with very different end-member models advocated today. We measured highly accurate Rayleighand Love-wave phase-velocity curves in broad period ranges (up to ...

S U M M A R Y We argue that subduction may be initiated at passive continental margins without shortening the lithosphere. Overcoming the lithosphere’s high compressive strength requires special circumstances, and these make it difficult to explain the nearly complete recycling of old sea-floor. Instead, we present a model that predicts tensile decoupling of the continental and oceanic lithosph...

Intraplate compressional deformation in the Central Indian Basin is expressed as linear E-W trending topographic undulations and geoid anomlies with characteristic spacings of approximately 200 km. To elucidate the nature of this deformation, we develop models of an oceanic lithosphere in a state of horizontal compression. The lithosphere is treated as a viscous or plastic layer of uniform stre...

[1] Although Mars is currently not tectonically active, it may have experienced plate tectonics early in its history. The southern hemisphere of Mars possesses a thick crust which probably renders the lithosphere positively buoyant. In this paper we present numerical and scaling arguments which show that if the area of positively buoyant lithosphere grows beyond a critical fraction ( 50% for Ma...