Full-coverage multibeam bathymetric mapping of twelve seamounts in the Gulf of Alaska reveals that
they are characterized by flat-topped summits (rarely with summit craters) and by terraced, or step-bench,
flanks. These summit plateaus contain relict volcanic features (e.g., flow levees, late-stage cones, and
collapse craters) and as such must have...
We use Ar-40-Ar-39 incremental heating to fingerprint bulk fluvial sediment entering the northeast Pacific Ocean, with the long-term intent of tracking sediment source and transport changes from the terrestrial system to the marine environment through time. We show reproducible age spectra from individual rivers accounting for the majority of sediment...
Within the Australian-Antarctic Discordance (AAD), a boundary exists between isotopically defined “Pacific-type” and “Indian-type” mid-ocean ridge basalt (MORB) erupted along the Southeast Indian Ridge (SEIR). This boundary has migrated westward beneath the easternmost AAD spreading segment at a minimum rate of 25 mm/yr since 4 Ma; however, its long-term history...
Results of ⁴⁰Ar–³⁹Ar Ar dating constrain the age of the submerged volcanic succession, part of the seaward-dip ping reflector sequence of the Southeast Greenland volcanic rifted margin, recovered during Leg 163. At the 3°Ne 6 drilling transect, the fully normally magnetized volcanic units at Holes 989B (Unit 1) and 990A...
A succession of basaltic lavas, volcaniclastic sediments, and lignite beds in the Holmatindur region of eastern Iceland provides the means for tying magnetic reversal stratigraphy and a record of major North Atlantic cooling to a precise radiometric timescale. A prominent part of the section is the Holmatindur classic bed, which...
We report the behavior of the earth's magnetic field for a transition recorded in lavas at the volcanic island of
Huahine in French Polynesia, south-central Pacific Ocean. Detailed intermediate fields are observed that record an
apparent N-N excursion. The available K-Ar ages indicate that most volcanic rocks of the southern...
This paper presents a new technique for shape and topology optimization of fluid channels using generative design synthesis methods. The proposed method uses the generative abilities of graph grammars with simulation and analysis power of conventional CFD methods. The graph grammar interpreter GraphSynth is used to carry out graph transformations,...
Determination of reliable crystallization ages by
K-Ar methods for young (<1 Ma), fresh basalts from the
seafloor has been frustrated by several effects. The small
amounts of radiogenic ⁴⁰Ar developed over these timescales in
such low-K rocks are difficult to resolve from predominantly
atmospheric ⁴⁰Ar. An additional concern is that...
At the submerged margins of the North Atlantic, andesitic to dacitic and basaltic volcanic rocks occur together. The silicic rocks were derived by processes requiring the presence of continental crust (crustal anatexis and/or contamination of mafic magmas) while the majority of the basaltic lavas had little or no contact with...
A key uncertainty concerning the effect of wildfire on carbon dynamics is the rate at which fire-killed biomass (e.g., dead trees) decays and emits carbon to the atmosphere. We used a ground-based approach to compute decomposition of forest biomass killed, but not combusted, in the Biscuit Fire of 2002, an...