-The chemical composition of mixed-layer serpentine/chlorite (Sp/Ch) in Tuscaloosa Formation sandstone was analyzed by energy dispersive X-ray spectroscopy (EDX) in the scanning electron miscroscope (SEM) and by X-ray diffraction (XRD). EDX results indicate little depth-controlled variation in composition, whereas XRD results suggest distinct decreases in octahedral Fe and tetrahedral A1. XRDde...

[1] The age-elevation pattern of thermochronologic data has been used for many years to estimate apparent erosion rates in orogenic settings. Recently, it has been suggested that thermochronologic data for detrital minerals from active river system sediments can be used as an effective proxy for bedrock age-elevation distributions, serving as an alternative method for erosion rate studies. This...

Groundwater flow in sedimentary rock saprolite, and in soils derived from this material, is strongly influenced by sedimentary layering and fractures inherited from the parent bedrock. The main objectives of this study were to determine whether parent bedrock lithology and infilling of fractures and other macropores with pedogenically derived clays and Fe/Mn oxides also play major roles in cont...

It has now been well established that the depth of bedrock is a key parameter in assessing the impact of local site conditions on seismic hazard analysis. Where conventional geotechnical testing like standard penetration test (SPT) or cone penetration test (CPT) requires a far greater cost and manpower to be used for such purposes, geophysical testing like ground-penetrating radar (GPR) and mul...

Serpentinization is a widespread process that affects large-scale geodynamic processes along plate boundaries, including continental breakup, seafloor spreading, and subduction. Documenting the timing of serpentinization is critical for our understanding of these processes, but direct dating of serpentinites has been challenging or impossible. We present the first application of magnetite (U-Th...

Hyperaccumulation of Ni by plants is hypothesized to function as an elemental defense against herbivores and pathogens. Laboratory experiments have documented toxic effects to herbivores consuming high-Ni plant tissues, but this paper reports the first experiment to examine the defensive effectiveness of Ni hyperaccumulation under field conditions. The experiment was conducted at an ultramafic ...

The surface waters at the ultramafic ophiolitic outcrop in Chimaera, Turkey, are characterized by high pH values and high metal levels due to the percolation of fluids through areas of active serpentinization. We describe the influence of the liquid chemistry, mineralogy, and H2 and CH4 levels on the bacterial community structure in a semidry, exposed, ultramafic environment. The bacterial and ...

Two dives of the DSV Shinkai 6500 in the Mariana Trough back-arc basin in the western Pacific sampled back-arc basin mantle exposures. Reports of peridotite exposures in back-arc basin setting are very limited and the lack of samples has hindered our understanding of this important aspect of lithospheric evolution. The Mariana Trough is a slow-spreading ridge, and ultramafic exposures with asso...

Hydrothermal venting and the formation of carbonate chimneys in the Lost City hydrothermal field (LCHF) are driven predominantly by serpentinization reactions and cooling of mantle rocks, resulting in a highly reducing, high-pH environment with abundant dissolved hydrogen and methane. Phylogenetic and terminal restriction fragment length polymorphism analyses of 16S rRNA genes in fluids and car...