[1] We show that the two-dimensional coherence between topography and Bouguer gravity is anisotropic throughout most of the Canadian Shield, excepted Hudson Bay Basin. We interpret the axis of maximum coherence as the direction where the lithosphere is weakest. In the southeastern Shield and the Appalachians, the azimuthally averaged coherence cannot be fitted by the thin elastic plate model. I...

A tomographic image of the upper mantle beneath central Tibet from INDEPTH data has revealed a subvertical high-velocity zone from approximately 100- to approximately 400-kilometers depth, located approximately south of the Bangong-Nujiang Suture. We interpret this zone to be downwelling Indian mantle lithosphere. This additional lithosphere would account for the total amount of shortening in t...

The relative proportions of metal residing in ore in the lithosphere, in use in products providing services, and in waste deposits measure our progress from exclusive use of virgin ore toward full dependence on sustained use of recycled metal. In the U.S. at present, the copper contents of these three repositories are roughly equivalent, but metal in service continues to increase. Providing tod...

The most spectacular example of a plate convergence event on Earth is the motion of the Indian plate towards Eurasia at speeds in excess of 18 cmyr−1 (ref. 1), and the subsequent collision. Continental buoyancy usually stalls subduction shortly after collision, as is seen in most sections of the Alpine–Himalayan chain. However, in the Indian section of this chain, plate velocities were merely r...

In order to understand the effects of contractional and extensional tectonics on thick, mantle roots, we have undertaken a systematic study of mantle xenoliths from the Labait volcano, which lies within the East African Rift on the eastern boundary of the Archean Tanzanian craton. The Re-Os systematics of the Labait xenoliths show that ancient, refractory lithosphere is present to depths of ;14...

Regions near Enceladus’ equator, Sarandib and Diyar Planitia, contain extensive sets of parallel ridges and troughs that may be diagnostic of the region’s formation conditions. We present photoclinometry profiles across these ridges and troughs, which indicate that they are periodic, low-slope features with dominant wavelengths of 3 to 4 km and amplitudes between 100 and 400 m. The morphology o...

Article history: We explore the sensitivity o Received 1 September 2007 Received in revised form 25 February 2008 Accepted 27 February 2008 Available online 18 March 2008