The elemental defense hypothesis proposes that some plants hyperaccumulate toxic elements as a defense mechanism. In this study the effectiveness of selenium (Se) as an arthropod deterrent was investigated under field conditions. Arthropod loads were measured over two growing seasons in Se hyperaccumulator habitats in Colorado, USA, comparing Se hyperaccumulator species (Astragalus bisulcatus a...

[1] Drilling during ODP Leg 209, dredging, and submersible dives have delineated an anomalous stretch of the Mid-Atlantic Ridge north and south of the 15 200N Fracture Zone. The seafloor here consists dominantly of mantle peridotite with gabbroic intrusions that in places is covered by a thin, discontinuous extrusive volcanic layer. Thick lithosphere (10–20 km) in this region inhibits magma fro...

Trieloff et al. (1) provided neon isotope data to argue that mantle neon originates as a trapped component in meteorites rather than having a pristine solar composition. That finding, if true, has important consequences for understanding the mechanism of volatile input into the mantle, because it rules out models involving direct incorporation of solar gases. The main argument that Trieloff et ...

[1] Interpretation of the EarthScope MT (magnetotelluric) data requires the development of a large‐scale inversion method which can address two common problems of 3D MT inversion: computational time andmemory requirements. We have developed an efficient method of 3D MT inversion based on an IE (integral equation) formulation of the MT forward modeling problem and a receiver footprint approach, ...

Experimental approaches attempt to determine the routes by which crustal carbonatite magmas can be derived from C02-bearing peridotite at high pressures. The intimate association of kimberlite and carbonatite on a small scale il· lustrates links in the processes. Carbonation of peridotite by C02 can cause the generation of near-solidus carbonatitic liquid from mantle peridotite at depths greate...

We compare observed Pioneer Venus orbiter (PVO) gravity profiles over Aphrodite Terra to profiles predicted from models of thermal isostasy, mantle convection, and Airy compensation. Similar approaches are used in order to investigate how well the models can be distinguished with the PVO data. Topography profiles across Aphrodite are compared to model spreading ridge profiles in order to furthe...

S U M M A R Y The formation of narrow, rapidly deforming plate boundaries separating strong plate interiors are integral components of the generation of plate tectonics from mantle convection. The development of narrow plate boundaries requires the interaction of a non-linear rheology and convection. One such non-linear rheology is two-phase damage theory which employs a nonequilibrium relation...

Introduction and Background: Northeast Arabia Terra, west and north of Syrtis Major, has long been known to be characterized by significant terrain mantling and exhumation [1-3]. There are two widespread geological units at a scale of 1:15M [1]: dissected terrain (Npld; more highly dissected by valley networks (VN) than cratered unit; covers extensive area S and W of Syr-tis Major, interpreted ...