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Unique Identification: Laminated sulfidic silt
Site name: Wallowa
Light type: Plane-Polarized Light
Magnification: 100.0
Submitted by: Mark Shapley
Notes: Siliciclastic medium silt and diatom frustules with abundant, fine-grained opaque minerals. This sediment reacted dramatically within an hour or two of core splitting, as reactive Fe sulfides oxidized in contact with air.
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Unique Identification: Laminated sulfidic silt
Site name: Wallowa
Light type: Cross-Polarized Light
Magnification: 100.0
Submitted by: Mark Shapley
Notes: Medium siliciclastic (quartz + feldspars) angular silt; isotropic diatoms and opaque iron sulfides are invisible in cross-polarized light.
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Unique Identification: Laminated sulfidic silt
Site name: Wallowa
Light type: Plane-Polarized Light
Magnification: 200.0
Submitted by: Mark Shapley
Notes: Iron-bearing silicate minerals derived from igneous rocks (flaky biotite upper left and lower right; prismatic pyroxenes top center and bottom near scale bar) are potential sources of reactive Fe contributing to iron sulfide formation in this sediment.
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Unique Identification: Laminated sulfidic silt
Site name: Wallowa
Light type: Cross-Polarized Light
Magnification: 200.0
Submitted by: Mark Shapley
Notes: Birefringent pyroxene grain in upper middle of image is in extinction orientation; pyroxene near scale bar shows moderate birefringence. Axial view of biotite flake (upper left) shows minimal birefringence.
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Unique Identification: Laminated sulfidic silt
Site name: Wallowa
Light type: Plane-Polarized Light
Magnification: 400.0
Submitted by: Mark Shapley
Notes: Alteration of volcanic glass (irregular grains with conchoidal fracture, center and lower right, nearly isotropic in cross-polarized light below) provide another potential source of Fe for the formation of reactive iron sulfides.
Image Tags: none
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Unique Identification: Laminated sulfidic silt
Site name: Wallowa
Light type: Cross-Polarized Light
Magnification: 400.0
Submitted by: Mark Shapley
Notes: none
Image Tags: none
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