abstract soil crust decreases soil infiltration and prevents plant stablishment. thus reduction of crust effects is a prominent way to avert desertification. this study was conducted to investigate the effect of polyacrylamide on emergence of canola seedlings in a crusted soil and some physicochemical properties of soil such as ph, ec, sar and bulk density in a field located in date and tropica...

Introduction: A majority of the mountains on Io are tectonic, upthrusted blocks [1-8]. The mechanism behind their formation, however, is unknown. Mountain formation may be indirectly related to the prolific volcanism on Io [3]. Three major mountain formation hypotheses following from this idea include: • convection-modified subsidence: global compressional stresses (subsidence) are created by t...

It has long been recognized that mare basalts on the Moon are preferentially located both on the Earth-facing hemisphere and within large impact basins. A popular model that accounts for this observation assumes that these magmas were denser than the lunar crust, that they accumulated at the crust^mantle interface, and that eruptions occurred only when this magma chamber became overpressurized....

Introduction: Understanding the Moon's thermal and magmatic evolution entails understanding the origin of the earliest crust, in particular whether it formed from a magma ocean [1]. The energy of late stage planet-building impacts would be at least sufficient to form magma oceans and possibly enough to melt whole planets [2]. The solidification history of the magma ocean will place constraints ...

Arc magmas and the continental crust share many chemical features, but a major question remains as to whether these features are created by subduction or are recycled from subducting sediment. This question is explored here using Th/La, which is low in oceanic basalts (<0 2), elevated in the continents (>0 25) and varies in arc basalts and marine sediments (0 09–0 34). Volcanic arcs form linear...

There is growing evidence that the top part of the oceanic mantle is pervasively serpentinized prior to subduction. Because the interior of a subducting slab heats up slowly, the serpentinized layer can be preserved for tens of Myr, thereby forming a weak zone that allows for mechanical decoupling between the oceanic crust and underlying lithospheric mantle. Once the crust is eclogitized, a she...

Here, the state of our knowledge regarding the interior dynamics and evolution of habitable terrestrial planets including Earth and super-Earths is reviewed, and illustrated using state-of-the-art numerical models. Convection of the rocky mantle is the key process that drives the evolution of the interior: it causes plate tectonics, controls heat loss from the metallic core (which generates the...

The collision of thickened crust with subduction zones significantly modifies subduction. These accretion events lead to net growth of continents and drive much of the subduction-related tectonism. Terrane collision may also have a profound effect on the size, coupling, and rupture characteristics of large intraplate earthquakes. The present accretion of exotic terranes with the Alaska subducti...