The formation of deep-sea Limu o Pele

Abstract

Deep-sea sheet hyaloclastite consists mostly of sand-sized blocky and splinter-shaped shards, but also contains subordinate mm-to cm-sized thin, curved, and wrinkled plates and sheets of sideromelane. This latter type of shard, termed Limu o Pele, has been observed forming subaerially on Kilauea by entrapment of water in flowing lava followed by expansion of steam to form large bubbles which burst into thin fragments. Deepmarine limu has been inferred, from comparative morphological studies and assessment of physical bubbleforming conditions, to form in a similar way but with the increased ambient pressure and the higher viscosity of water reducing bubble expansion. Differing mechanisms of heat transfer and rates of magma chilling also modify the limu-forming process in the deep sea. This paper evaluates a variety of deep-sea limu-forming processes and develops a new and quantitatively supported model, based on observed limu-forming processes and criteria derived from dive samples and observations at Seamount Six, Cocos Plate. It is inferred that water and/or watersaturated sediment was trapped in extremely thin, fluid and rapidly advancing lava flows by various processes. Bubble formation might also occur during small-scale magma-fountaining driven by magmatic volatile exsolution and extreme vent constriction or during collapse of pillows and rapid drainage of the magma, but we found no deposits clearly resulting from these processes.

Geochemical approaches to the quantification of dispersed volcanic ash in marine sediment

“…Subaqueous eruptions can lead to significant volcanic input (e.g., Fiske et al 2001;Maicher and White 2001;White et al 2003;Tani et al 2008). Fiske et al (2001, their p. 822) in particular note how the finestgrained fraction is missing from caldera deposits in the Izu-Bonin system.…”

Deep submarine pyroclastic eruptions: theory and predicted landforms and deposits

“…Lonsdale and Batiza (1980) reported the presence of extensive £ows of volcaniclastics on the summits of four seamounts 8001 200 m above the £anks of the EPR interpreted to have formed in deep-water phreatomagmatic eruptions (see also Batiza et al, 1984). Smith and Batiza (1989) documented extensive volcaniclastic deposits at depths from 1240^2500 m on six additional seamounts near the EPR and located several vent areas (see also Maicher et al, 2000;Maicher and White, 2001). These deposits occur at a depth where pressure would seem to preclude the normal exsolution of magmatic volatiles to such a degree that they disrupt (e.g.…”

No depth limit to hydrovolcanic limu o Pele: analysis of limu from Lō`ihi Seamount, Hawai`i

“…Recognizing the morphologic similarity of deep sea and littoral limu, Maicher et al (2000) and Clague et al (2000) inferred that the same littoral hydrovolcanic process observed at Kīlauea's coastline also generated deep sea limu, and the process was quantified for limu in hyaloclastites at Seamount Six, Cocos Plate by Maicher and White (2001). Reduced limu bubble size in the deep sea (Clague et al 2000;Maicher and White 2001) as compared to in the littoral environment, was considered to be a consequence of the reduced expansion of seawater at high hydrostatic pressure.…”

“…Reduced limu bubble size in the deep sea (Clague et al 2000;Maicher and White 2001) as compared to in the littoral environment, was considered to be a consequence of the reduced expansion of seawater at high hydrostatic pressure.…”