[1] High-resolution images of the walls exposed in Valles Marineris reveal variations in appearance and degree of layering indicating various lithologies comprise the Tharsis plateau. The layered wall rock has been proposed to result from effusive flood basalt volcanism or interbedded sediments and volcanics. We present observations of unlayered rock that indicate layering extends to a greater ...

An unbiased estimate of the arithmetic mean of the He/He ratio (R) of basalts from the global spreading ridge system is 9.14 + 3.59 Ra (n=503), where Ra is the atmospheric ratio and n is the number of data points. The + two standard deviation (2σ) range covers much of the oceanic island and continental flood basalt data that have been attributed to ‘plume’ or ‘lower mantle’ components. The high...

Wrangellia consists largely of an oceanic plateau, a vast outpouring of basalt and more Mg-rich magma that erupted onto the ocean floor and was subsequently accreted to the western margin of the North American plate. Flood basalts form extensive sequences on Vancouver Island and are believed to have formed by melting in a mantle plume (an upwelling zone of hot mantle rock). They form the oceani...

We explore Fe/Mn and Nb/Ta ratios of basalts as potential tracers for differentiating melts of recycled mafic crustal lithologies from peridotitic melts. Trace elements and Fe/Mn ratios of the Mesozoic and Cenozoic basalts from East China were analyzed by ICP-MS. Low Nb/Ta ratios (15.4 ± 0.3 (2r, n = 45)), high Nb and Ta contents (60.1 and 4.01 ppm) and high Fe/ Mn ratios (64.7 ± 1.5 (2r, n = 4...