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SAMPLE INFO : 4_64-27_104
Sample ID:4_64-27_104
Station ID:Nayudu_core_4
Sample Type 1:Tephra Fall
Text Description:
Sample ID is the core number_cruise-and-sample-number_length (cm) from Table 1 in Nayudu (1964), which contains the list of the cores containing volcanic ash, their position, depth and length. Depth of 2,000 fathoms. Katmai ash is present as a 1-cm-thick layer in this core; the color of the ash varies from pale orange (10YR 8/2) to pale yellowish brown (10YR 6/2). A middle basic ash is also present from 38-40 cm, and is brownish-black with a clearly defined base and poorly marked upper limit. Predominantly grayish-brown glass shards that are irregular and splintery with inclusions of gas bubbles and minerals, the most common being plagioclase, feldspar, and pyroxene. Shards show little to no alteration. Glass content varies from 70-80% and the mineral and crystal fragments make up the rest. Hypersthene is the dominant mineral and some of the other important mineral constituents are basaltic hornblende, augite, magnetite and plagioclase (andesine and labradorite). The average refractive index of the glass is 1.562 +/- 0.002. Inferred to be 12,000-15,000 years old.

Volcanic ash deposits in the Gulf of Alaska and problems of correlation of deep-sea ash deposits


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Page modified: August 1, 2017 15:29
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