| Id | Identification Type | Name | Description | Distinguishing Features | Tags |
|---|---|---|---|---|---|
| 61 | Lithofacies | Tephra | Tephra, or volcanic ash, is a mixture of volcanic glass and crystalline grains derived from the same volcanic source. A tephra unit in a core may be predominantly crystalline and coarse-grained at the base, grading upwards to finer, more glassy grains. See volcanic glass for a detailed description and identification; crystalline components can be identified based on their optical mineralogical characteristics.
Isotropic conchoidally fractured volcanic glass (typically dominant) in variable proportions with crystalline volcanic constituents. Glass may be altered to any of a suite of secondary minerals, typically of low and variable birefringence. |
volcanic-glass isotropic conchoidal vesicular |
|
| 114 | Lithofacies | Diatomaceous carbonate mud | Describes a lithofacies composed of >50% authigenic carbonate minerals, with diatom frustules as the second-most abundant component.
Diatom frustules prominent but secondary to carbonate minerals; organic matter (amorphous or fragmentary) variable, subordinate; clastic mineral matter subordinate, may be absent. |
high-birefringence calcareous authigenic biogenic |
|
| 115 | Lithofacies | Calcareous silt | Lithofacies comprising >50% detrital mineral material in the silt size range (4-63 microns), with calcium carbonate the most abundant secondary component.
Carbonate grains prominent but secondary; biogenic components variable but subordinate; mineral composition of detrital component depends on erosional sources and their lithologies. |
silty calcareous fine-grained |
|
| 116 | Lithofacies | Organic-rich carbonate mud with pyrite | Refers to a lithofacies comprising >50% chemically precipitated carbonate minerals, abundant secondary organic matter, and prominent accessory pyrite.
Prominent co-occurrence of carbonate and opaque minerals. Likely to be pungent (H2S). |
opaque black high-birefringence pungent stinky |
|
| 163 | Lithofacies | Organic-rich Diatom Ooze | Refers to a lithofacies comprising >50% diatom frustules, with organic matter (amorphous and/or fragmentary) making up the second-most abundant constituent.
Prominence of diatom frustules; diatoms may be diverse, or essentially monospecific. Carbonate minerals subordinate, or absent. Clastic silt subordinate, or absent. Diagenetic minerals (e.g., vivianite; pyrite) occur commonly, but are subordinate. |
circular transparent colorless rice-shape brown amorphous |
|
| 164 | Lithofacies | Peat | Lithofacies referring to a sediment consisting of >80% authigenically produced organic matter.
High proportion of organic matter to mineral grains. Organic material may be coarsely fragmentary, or degraded. |
organic-matter fibrous fragmentary bryophyte woody |
|
| 165 | Lithofacies | Turbidite sequence | Lithofacies comprising one or more graded beds, interpreted as the product of gravity-driven mass transport and density separation of sediment constituents.
Sharp, sometimes erosional basal contact; normal (fining-upward) size grading; may have distinctive light-colored uppermost layer of fine silt or clay-sized material; may have relative concentration of heavy minerals at deposit base. |
graded density gravity-deposit Bouma-sequence |
|
| 168 | Lithofacies | Laminated sulfidic silt | Describes a lithofacies comprising finely structured clastic sediment with prominent accessory sulfide minerals, especially fine reactive monosulfide (mackinawite).
Distinguished by fine-scale bedding and abundance of opaque minerals; often highly pungent when freshly exposed. |
fine-scale-bedding
pungent |
opaque black pungent reactive diatomaceous |
| 169 | Lithofacies | Diatom ooze | Lithofacies comprising >50% diatom frustules, with secondary contributions of detrital and/or chemically precipitated material.
High proportion of diatom frustules; intervals deposited during 'blooms' may be nearly pure diatoms, with cheesy or clotted surface texture. Carbonate minerals subordinate, or absent. |
isotropic clotted |
|
| 170 | Lithofacies | Clay turbidite cap | Describes the finest, suspended component of a subaqueous density-flow deposit, settled out of the water column at the end of a transport event.
Position above fining-upward sequence; grain size may be in fine silt or clay range. |
sorted fine-grained graded |
|
| 172 | Lithofacies | Tephra - Glacier Peak G | Lithofacies defined as the directly deposited ejecta from the 'Series G' Plinian eruption of Glacier Peak, Washington state, ca. 13500 cal. yr BP.
Distinguished indisputably by elemental chemistry. Identification is frequently inferred by bracketing ages, geographic distribution, and general appearance. |
volcanic-glass isotropic conchoidal vesicular Cascades |
|
| 173 | Lithofacies | Tephra - Mt. St. Helens J | Lithofacies defined as the directly deposited ejecta from the 'Series J' eruption of Mt. Saint Helens, Washinton state, ca. 12000(?) cal. yr BP.
Distinguished indisputably by elemental chemistry. Identification is frequently inferred by bracketing ages, geographic distribution, and general appearance. |
volcanic-glass isotropic conchoidal vesicular Cascades |
|
| 174 | Lithofacies | Glacial varves | Lithofacies comprising annually laminated sequences of sand, silt or clay deposited in a glacially-influenced lacustrine (or marine) setting.
Repetitively laminated variations in grain size from sand to clay, representing seasonal variations in glacial melt-water cycles and sediment transport; dropstones may be present if deposited in an ice-contact setting. |
laminated graded rythmite glacial |
|
| 175 | Lithofacies | Banded carbonate mud | Lithofacies comprising >50% carbonate minerals, repetitively banded on centimeter scale with more and less organic-rich compositions.
Centimeter to decimeter darker and lighter banding of dominantly calcareous lithology. |
banded calcareous organic-matter |
|
| 176 | Lithofacies | Tephra- Mazama | Lithofacies defined as the directly deposited ejecta from the cataclysmic Plinian eruption of Mt. Mazama, Oregon, ca. 7630 cal. yr BP.
Distinguished indisputably by elemental chemistry. Identification is frequently inferred by bracketing ages, geographic distribution, and general appearance. |
volcanic-glass isotropic conchoidal vesicular Cascades Holocene |
|
| 177 | Lithofacies | Tephra - Mount Saint Helens Y | Lithofacies defined as the directly deposited ejecta from the 'Series Y' eruption of Mt. Saint Helens, Washinton state, ca. 3750 cal. yr BP.
Distinguished indisputably by elemental chemistry. Identification is frequently inferred by bracketing ages, geographic distribution, and general appearance. |
volcanic-glass isotropic conchoidal vesicular Cascades |
|
| 179 | Lithofacies | Tephra - mafic | Lithofacies defined as the directly deposited ejecta of mafic (typically basaltic) volcanic eruptions. |
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