Inorganics

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.

Contact Information

CSD Facility

116 Church Street NE, Minneapolis, MN 55455

P: 612-626-7889

Connect on Social Media