What is an example of authigenic sediment?
authigenic sediment, deep-sea sediment that has been formed in place on the seafloor. The most significant authigenic sediments in modern ocean basins are metal-rich sediments and manganese nodules. Metal-rich sediments include those enriched by iron, manganese, copper, chromium, and lead.
What are authigenic minerals?
Authigenesis is the process whereby a mineral or sedimentary rock deposit is generated where it is found or observed. Authigenic sedimentary minerals form during sedimentation by precipitation or recrystallization instead of being transported from elsewhere (allogenic) by water or wind.
What is authigenic pyrite?
Authigenic pyrite from dissimilatory sulfate reduction is a small fraction of the pyrite found in the methane dominant and low in organic carbon environment, with majority of pyrite derived from AOM-SR.
How is glauconite formed?
Glauconite forms by three principal processes: alteration of the fecal pellets of bottom-dwelling organisms; modification of particles of illitic and biotitic clays by seawater; and direct precipitation from seawater. Particles of glauconite are generally sand-sized or finer.
What is authigenic quartz?
Authigenic microcrystalline quartz aggregates filled in primary pore space and destroyed primary interparticle porosity. However these authigenic quartz can restrain compaction and preserve the internal pore structure as a rigid framework.
What are authigenic carbonates?
Authigenic carbonate refers to any carbonate mineral precipitated inorganically in situ, whether at the sediment-water interface or within sediment pore waters.
Is quartz authigenic or allogenic?
Pertaining to minerals or materials that grow in place with a rock, rather than having been transported and deposited. These include quartz, chlorite, and other pore-filling minerals or cements that grow during diagenesis. Evaporite minerals are authigenic, or formed in situ.
What are authigenic sediments quizlet?
authigenic sediment. Sediment formed directly by precipitation from seawater (hydrogenous sediment).
What are authigenic aluminium hydroxides?
Gouleau et al. (1982) describe authigenic aluminium hydroxides, occurring as short prismatic crystals, isolated and as part of small aggregates (see also Marius, 1985 ). Micromorphological features of pre-Quaternary example are illustrated for a Jurassic swamp deposit containing sodium-rich alunite that formed before compaction ( Goldbery, 1978 ).
What are authauthigenic minerals?
Authigenic minerals are dominated by carbonate cements and filamentous lathes of pore-lining and pore-filling illite. James G. Speight, in Subsea and Deepwater Oil and Gas Science and Technology, 2015
Are authigenic mineral reactions bacterially mediated?
Some authigenic mineral reactions are bacterially mediated—the bacteria modify the immediate geochemical environment, inducing mineral formation.