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Text Description: orange fragmental deposit with patchy distribution around caldera rim; mantles Big Breccia deposit and the swales cut in the breccia; includes thoroughly hydrothermally altered blocks and agglutinated blocks of all sizes to decimeters-scale. Also includes 10-20% fresh grey lavas; matrix is orange due to comminuted hydrothermally altered material. Matrix is sandy with some clay component. Some agglutinated blocks are stratified. No pumice seen. Orange sediments atop ignimbrite near Y-3 include abundant orange-altered ferrocreted lake sediment clasts. Implies the orange hydrothermally altered deposit postdates the ignimbrite, too. Exposed thickness 5 to 8 m. MP typically decimeters; ML = 2+m. References: ![]() |
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