Physico-chemical changes in sediments occurring after their deposition
A form of diagenesis is permineralization, in which buried organisms are replaced by minerals. These trilobites (Lloydolithus) were replaced by pyrite during a specific type of permineralization called pyritization.Permineralization in vertebra from Valgipes bucklandi
Diagenesis (/ˌdaɪ.əˈdʒɛnəsɪs/) is the process that describes physical and chemical changes in sediments first caused by water-rock interactions, microbial activity, and compaction after their deposition. Increased pressure and temperature only start to play a role as sediments become buried much deeper in the Earth's crust.[1] In the early stages, the transformation of poorly consolidated sediments into sedimentary rock (lithification) is simply accompanied by a reduction in porosity and water expulsion (clay sediments), while their main mineralogical assemblages remain unaltered. As the rock is carried deeper by further deposition above, its organic content is progressively transformed into kerogens and bitumens.
The process of diagenesis excludes surface alteration (weathering) and deep metamorphism. There is no sharp boundary between diagenesis and metamorphism, but the latter occurs at higher temperatures and pressures. Hydrothermal solutions, meteoric groundwater, rock porosity, permeability, dissolution/precipitation reactions, and time are all influential factors.
After deposition, sediments are compacted as they are buried beneath successive layers of sediment and cemented by minerals that precipitate from solution. Grains of sediment, rock fragments and fossils can be replaced by other minerals (e.g. calcite, siderite, pyrite or marcasite) during diagenesis. Porosity usually decreases during diagenesis, except in rare cases such as dissolution of minerals and dolomitization.
The study of diagenesis in rocks is used to understand the geologic history they have undergone and the nature and type of fluids that have circulated through them. From a commercial standpoint, such studies aid in assessing the likelihood of finding various economically viable mineral and hydrocarbon deposits.
The process of diagenesis is also important in the decomposition of bone tissue.[2]
^Marshak, Stephen (2009). Essentials of Geology (3rd ed.). W. W. Norton & Company. ISBN 978-0393196566.
^Hedges, R. E. (2002). "Bone Diagenesis: An Overview of Processes". Archaeometry. 44 (3): 319–28. doi:10.1111/1475-4754.00064.
The process of diagenesis excludes surface alteration (weathering) and deep metamorphism. There is no sharp boundary between diagenesis and metamorphism...
older sediments are buried by younger sediments, and they undergo diagenesis. Diagenesis includes all the chemical, physical, and biological changes, exclusive...
than the modern ocean. Diagenesis is the process in which sediments are compacted and turned into solid rock. During diagenesis of carbonate sediments...
sediments, and it undergoes diagenesis. This mostly consists of compaction and lithification of the sand. Early stages of diagenesis, described as eogenesis...
begin to undergo diagenesis. This mostly consists of compaction and lithification of the clay and silt particles. Early stages of diagenesis, described as...
identified by Lyell, 1837. Lyell had a clear perception of the regional diagenesis sequence in sedimentary rocks that remains valid today. It begins 'A'...
contain traces of skin, feathers or even soft tissues. This is a form of diagenesis. In some cases, the original remains of the organism completely dissolve...
cementation through the various stages of diagenesis discussed below. Eogenesis refers to the early stages of diagenesis. This can take place at very shallow...
the original sediments, and as a secondary mineral, deposited during diagenesis. Pyrite and marcasite commonly occur as replacement pseudomorphs after...
this information is lost or distorted by the fossilization process or diagenesis of the enclosing sediments, making interpretation difficult. Some other...
iron hydroxide and silica gels to banded iron formation is an example of diagenesis, the conversion of sediments into solid rock. There is evidence that banded...
changes in compressed sedimentary rock formations during the process of diagenesis. One hypothesis is that a gelatinous material fills cavities in the sediment...
Compact mass formed by precipitation of mineral cement between particles Diagenesis – Physico-chemical changes in sediments occurring after their deposition...
much lower temperatures and pressures associated with diagenesis of sedimentary rock, but diagenesis has cemented the rock so thoroughly that microscopic...
widespread in sulfate-rich environments. Lycopane may be sourced from diagenesis of an unsaturated precursor such as lycopene, a carotenoid that is abundantly...
"Molecular taphonomy of animal and plant cuticles: selective preservation and diagenesis". Philosophical Transactions of the Royal Society B: Biological Sciences...
components to understanding geologic history due to processes such as diagenesis in which carbonates undergo compositional changes based on kinetic effects...
melting, crystallization, fractionation, metamorphism, weathering, and diagenesis. Living organisms also contribute to this geologic cycle. For example...
Retrieved 7 June 2009. Nothdurft, Luke D. (2007). Microstructure and early diagenesis of recent reef building scleractinian corals, Heron reef, Great Barrier...
sediments are buried but before the sediment is fully lithified during diagenesis. They typically form when a mineral precipitates and cements sediment...
interlayering. These purely sedimentary differences become enhanced during diagenesis as the silica leaves the clayey layers and migrates towards the opal-rich...
the deeper oil shales of the Green River Formation during burial and diagenesis. Bitumen is similar to the organic matter in carbonaceous meteorites....
Calcified Metaphytes in the Latest Proterozoic Nama Group, Namibia: Origin, Diagenesis, and Implications". Journal of Paleontology. 65 (1): 1–18. Bibcode:1991JPal...
understanding of the geochemistry of connate fluids is important if the diagenesis of the rock is to be quantified. The solutes in the connate fluids often...
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