Before its collision with Eurasia1–5, the Indian Plate moved rapidly, at rates exceeding 140mmyr−1 for a period of 20 million years1,3–7. This motion is 50 to 100% faster than the maximum sustained rate of convergence of themain tectonic plates today8. The cause of such high rates of convergence is unclear and not reproduced by numerical models9,10. Here we show that existing geological data11,...

[1] We expand the theory of critically tapered Coulomb wedge for accretionary prisms by considering stress changes in subduction earthquake cycles. Building on the Coulomb plasticity of the classical theory, we assume an elastic–perfectly Coulomb plastic rheology and derive exact stress solutions for stable and critical wedges. The new theory postulates that the actively deforming, most seaward...

[1] Adakitic melts from Papua New Guinea (PNG) show adakitic geochemical characteristics, yet their geodynamic context is unclear. Modern adakites are associated with hot-slab melting and/or remelting of orogenic mafic underplate at convergent margins. Rift-propagation over collision-modified lithosphere may explain the PNG adakite enigma, as PNG was influenced by rapid creation and subduction ...

Atmospheric carbon dioxide (CO2) data for the last 420 million years (My) show long-term fluctuations related to supercontinent cycles as well as shorter cycles at 26 to 32 My whose origin is unknown. Periodicities of 26 to 30 My occur in diverse geological phenomena including mass extinctions, flood basalt volcanism, ocean anoxic events, deposition of massive evaporites, sequence boundaries, a...

Understanding variations of slip distance along major thrust systems at convergent margins is an important issue for evaluation of near-trench slip and the potential generation of large tsunamis. We derived quantitative estimates of slip along ancient subduction fault systems by using the maturity of carbonaceous material (CM) of discrete slip zones as a proxy for temperature. We first obtained...

In contrast to continent/continent collision, arc-continent collision generates very short-lived orogeny because the buoyancy-driven impedance of the subduction of continental lithosphere, accompanied by arc/suprasubduction-zone ophiolite obduction, is relieved by subduction polarity reversal (flip). This tectonic principle is illustrated by the early Ordovician Grampian Orogeny in the British ...

One of the consequences of plate tectonics is that a spreading ridge will eventually approach a subduction zone. The problem whether the possible break-up of the approaching ridge will lead to the development of independent micro-plates, or not, is still unresolved. Some 4 million years ago the interaction between the Juan de Fuca Ridge and the Cascadia subduction zone resulted in ridge fragmen...

Much of the Earth's mantle was melted in the Moon-forming impact. Gases that were not partially soluble in the melt, such as water and CO2, formed a thick, deep atmosphere surrounding the post-impact Earth. This atmosphere was opaque to thermal radiation, allowing heat to escape to space only at the runaway greenhouse threshold of approximately 100 W m(-2). The duration of this runaway greenhou...

INTRODUCTION We use new geological and hydrodynamic models to simulate the sea floor deformation and tsunami runup and inundation in Cannon Beach, Oregon (Fig. 1) produced by Cascadia subduction zone (CSZ) earthquakes. We then compare the simulated inundation with inland extent of buried sand sheets inferred to be of tsunami origin. The CSZ exhibits similarities to other subduction zones around...

Mantle wedge regions in subduction zone settings show anomalously high electrical conductivity (~1 S/m) that has often been attributed to the presence of aqueous fluids released by slab dehydration. Laboratory-based measurements of the electrical conductivity of hydrous phases and aqueous fluids are significantly lower and cannot readily explain the geophysically observed anomalously high elect...