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Title: Rock Varnish on Hualalai and Mauna Kea Volcanoes, Hawai'i 
Author: Dorn, RI; Jull, AJT; Donahue, DJ; Linick, TW; Toolin, LJ; Moore, RB; Rubin, M; Gill, TE; Cahill, TA
Date: 1992-01
Publisher: University of Hawai'i Press
Citation: Dorn RI, Jull AJT, Donahue DJ, Linick TW, Toolin LJ, Moore RB, Rubin M, Gill TE, Cahill TA. 1992. Rock varnish on Hualalai and Mauna Kea Volcanoes, Hawai'i. Pac Sci 46(1): 11-34.
Abstract: Tropical rock varnishes found on Hualalai and Mauna Kea
Volcanoes, Hawai'i, vary systematically with time and environment. Radiocarbon
dating of encapsulated organic matter, (K+ + Ca2+)/Ti4+ ratios, and Zn,
Cu, and Ni trace element concentrations in rock varnish are consistent with lava
flowages established by K-Ar and 14C dating, where samples are collected from
arid microsites well away from the soil surface. However, inaccurate ages are
obtained from rock varnish in subsurface locations and from sites with abundant
lichens, cyanobacteria, and fungi that chemically erode varnish. In contrast with
continental deserts, Hawaiian varnishes commonly interfinger with and are less
common than rock coatings of amorphous silica. Laboratory experiments on
Hawaiian rock varnishes indicate that K and Ca are preferentially leached
relative to Ti over time and at higher temperatures. The location of in situ
leaching has been identified in Hawaiian varnishes as porous textures without
abundant detrital grains.
ISSN: 0030-8870
URI: http://hdl.handle.net/10125/1670

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