Systematic exploration of the continental lithosphere by deep seismic reflection profiling over the past 20 years has revolutionized our view of the deep crust and upper mantle. Major geological features have been traced to lower crustal depths. Certain deep crustal features have been traced into the underlying mantle (fossil subduction zones?). Some geotectonic boundaries, considered by genera...

[1] The geometry and properties of the interface of the Cocos plate beneath central Mexico are determined from the receiver functions (RFs) utilizing data from the Meso America Subduction Experiment (MASE). The RF image shows that the subducting oceanic crust is shallowly dipping to the north at 15° for 80 km from Acapulco and then horizontally underplates the continental crust for approximatel...

[1] High-pressure assemblages of subducted oceanic crust are denser than the normal upper mantle but less dense than the uppermost lower mantle. Thus subducted oceanic crust may accumulate at the base of the upper mantle. Direct observational evidence for this hypothesis, however, remains elusive. We present an analysis of a negativepolarity shear wave converted from compressional wave at a sei...

The sudden spin jumps, or glitches, commonly seen in isolated neutron stars are thought to represent angular momentum transfer between the crust and the liquid interior [1]. In this picture, as a neutron star’s crust spins down under magnetic torque, differential rotation develops between the stellar crust and a portion of the liquid interior. The more rapidly rotating component then acts as an...

Continental crust rises higher than oceanic crust because it is less dense: It is rich in Si and poor in Mg. However, basalt, which is derived from magma, is denser and has a higher ratio of Mg to Si than the rock that makes up mature continental crust. Cin-Ty Lee et al. argue that chemical weathering alters the composition of continental crust as it ages and helps give it its more buoyant char...

Because helium and heat production results from a common source, a continental He crustal flux of 4.65*10 14 mol m 2 s 1 has been estimated based on heat flow considerations. In addition, because the observed mantle He /heat flux ratio at the proximity of mid-ocean ridges (6.6*10 14 mol J ) is significantly lower than the radiogenic production ratio (1.5*10 12 mol J ), the presence of a terrest...

The movement of a low-viscosity crustal layer in response to topographic loading provides a potential mechanism for (1) eastward flow of the Asian lower crust causing the peripheral growth of the Tibetan Plateau and (2) southward flow of the Indian middle crust to be extruded along the Himalayan topographic front. Thermomechanical models for channel flow link such extrusion to focused orographi...

[1] Rifting of passive margins has, in some places, led to the development of extensive submerged continental platforms. Crustal thinning by a factor of two or more is at least partially accommodated by high-angle normal faults that extend through the brittle upper crust to the ductile parts of the lower crust. However, an approximately horizontal detachment zone has been postulated to explain ...