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LITHIFICATION
By: Admin Date: February 2, 2017, 11:16 pm
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Lithification
HTML https://www.britannica.com/science/lithification
Lithification, complex process whereby freshly deposited loose
grains of sediment are converted into rock. Lithification may
occur at the time a sediment is deposited or later. Cementation
is one of the main processes involved, particularly for
sandstones and conglomerates. In addition, reactions take place
within a sediment between various minerals and between minerals
and the fluids trapped in the pores; these reactions,
collectively termed authigenesis, may form new minerals or add
to others already present in the sediment. Minerals may be
dissolved and redistributed into nodules and other concretions,
and minerals in solution entering the sediment from another area
may be deposited or may react with minerals already present. The
sediment may be compacted by rearrangement of grains under
pressure, reducing pore space and driving out interstitial
liquid.
Lithification
HTML https://www.reference.com/science/process-lithification-260ed465d44a46db#full-answer
Lithification is the process by which sediment turns into
hardened rock. There are three ways in which lithification can
occur. These processes are called compaction, recrystallization
and cementation.
Compaction is a process of lithification that works for finer
particles only. Compaction occurs when particles such as clay
minerals are compressed. Coarser particles are not able to be
hardened with this process because compression does not make
them stick together.
Minerals such as limestone and aragonite can harden through the
process of recrystallization. These minerals are easily
dissolved in water, and the crystals that form from those
dissolved minerals are much harder than the original substances.
Cementation is the process where coarser grain sediments become
hardened rock. Water fills into the empty space between the
particles, and the ions in the water create new crystalline
formations among the sediments. When the water evaporates, the
sediment eventually seals and hardens, leaving behind a solid
piece of rock.
The creation of new minerals during the cementation process is
an example of authigenesis. Authigenesis is a term that
describes a process in which new minerals are created inside a
rock, or that the deposited minerals react and combine with the
minerals already present in the rock or sediment.
Cementation
sedimentary rock
HTML https://www.britannica.com/science/cementation-sedimentary-rock
Cementation, in geology, hardening and welding of clastic
sediments (those formed from preexisting rock fragments) by the
precipitation of mineral matter in the pore spaces. It is the
last stage in the formation of a sedimentary rock. The cement
forms an integral and important part of the rock, and its
precipitation affects the porosity and permeability of the rock.
Many minerals may become cements; the most common is silica
(generally quartz), but calcite and other carbonates also
undergo the process, as well as iron oxides, barite, anhydrite,
zeolites, and clay minerals.
It is unclear just how and when the cement is deposited. Part
seems to originate within the formation, and part seems to be
brought in from outside by circulating waters.
The reverse process is called dissolution. There is evidence
that dissolution has occurred in calcareous sandstones, in which
case the calcareous cement or grains are broken down in the same
manner as the solution of limestones. The frosted and etched
surfaces of quartz grains in some friable and loosely cemented
sandstones seem to indicate the former presence of a carbonate
cement that has been leached.
DIAGENESIS
HTML http://www.earth.northwestern.edu/public/seth/107/Rocks/lithification.htm
(William Deering Professor
and Institute for Policy Research Associate
Department of Earth and Planetary Sciences
Room F498, 2145 Sheridan Road
Northwestern University, Evanston, IL 60208-3130
Telephone: (847) 491-5265 FAX:(847) 491-8060
email: seth AT earth.northwestern.edu
(substitute "@" for AT) GEOLOGY 107 Our Dynamic Planet Fall
2005)
DIAGENESIS: MINERAL CHANGES OCCUR DUE TO INCREASING TEMPERATURE
AND PRESSURE
FOR EXAMPLE, FLINT IS CHEMICALLY PRECIPITATED SiO2 CHANGED TO
CRYSTALLINE ROCK
STRUCTURAL AND TEXTURAL EVIDENCE OF EARLY LITHIFICATION IN
FINE-GRAINED CARBONATE ROCKS
HTML http://onlinelibrary.wiley.com/doi/10.1111/j.1365-3091.1969.tb00877.x/abstract
Abstract
SUMMARY
Absence of compaction, intraformational breccias, resedimention,
internal sediments and synsedimentary hardgrounds indicate early
lithification of finegrained carbonate rocks. One of the factors
controlling early lithification is the purity of lime mud. Less
than 2% of insoluble residue (especially clay minerals) favours
cementation and recrystallisation before further sediment
accumulation causes compaction. Thus, early lithification is
terminated in or near the environment of sedimentation.
“Electrodiagenesis” is considered to be a possible mechanism for
cementation.
Electrodiagenesis
Possible role of electrical currents and potentials during
diagenesis
HTML http://jsedres.geoscienceworld.org/content/37/2/695
Abstract
Experimental work by the writers suggests that electrical
currents and potentials affect some diagenetic processes; this
may be termed "electrodiagenesis." It was discovered that
currents (produced chiefly by ionic exchange processes) flowing
through sediments may stimulate cementation and the formation of
authigenic minerals such as gibbsite, limonite, calcite,
hydrohematite, hydrogoethite (lepidocrocite), hisingerite,
allophane, allophanoid, gypsum, hematite, magnetite, nontronite,
trona, and natron (Na 2 CO 3 .10H 2 0). Currents may also cause
selective ion drive and explain zonation of some trace elements,
various minerals, etc.
Dr. George V. Chilingarian
Engineer and Scientist
Petroleum Engineering and Geology
HTML http://scip-lab.usc.edu/assets/009/53728.pdf
- 1951–1952. Proposed utilization of electrophoretic phenomen
on for separation of very fine grained sediments into grades.
Proved plating theory of chemicals which reduce viscosity of
muds.
- Possible Role of Electrical Currents and Potentials during
Diagenesis
(“Electrodiagenesis”). J. Sediment. Petrology, June 1967, pp.
695–698.
- 1956–1968. Worked on electrochemical stabilization of weak
grounds, and
electrical dewatering. Discovered that clays are destroyed on
application of
electrical current. Showed formation of new minerals in the
process. Coined a new
term “Electrodiagenesis” which explains some previously
unexplained phenomena.
- 1956–1968. Pioneered high-pressure compaction studies of
sediments in USA.
His pressure verse porosity curves are used extensively in
petroleum industryelectrical logging, subsidence, etc.. Showed
that chemistry of solutions squeezed out of clays changes with
pressure. Established pressures at which oriented water begins
to be squeezed out, and proposed a new theory of migration of
oil. Showed possibility of estimating overburden pressure from
X-ray analysis.
- 1956–1968. Worked on electrochemical stabilization of weak
grounds, and
electrical dewatering. Discovered that clays are destroyed on
application of
electrical current. Showed formation of new minerals in the
process. Coined a new
term “Electrodiagenesis” which explains some previously
unexplained phenomena.
- Established definite correlation between porosity and
permeability of carbonate rocks (microfractured) by introducing
two additional variables-specific surface area and irreducible
fluid saturation.
- His work on carbonate reservoir rocks was pioneering as
evidenced by the
publication of the first books on the subject. For example, he
proved that in many
cases dolomitization gives rise to porosity. Also, he showed
that many carbonates
are oil-wet, at a time when most petroleum engineers and
geologists believed that
all rocks are water-wet.
- Through extensive laboratory experiments he proposed the use
of electric current in well stimulation and in secondary and
tertiary oil recovery.
- He showed that sands are just as compactable as clays.
- It is well established that in many cases there is very poor
correlation between
porosity and permeability. Yet; if one uses Professor
Chilingarian's definition of
“effective porosity,” namely, porosity excluding pores and
cracks occupied by the
irreducible fluid, then there is indeed a very good correlation
between “effective
porosity” and permeability.
-----
Minerals in Sediments
HTML http://homepage.usask.ca/~mjr347/prog/geoe118/geoe118.021.html
(c) Department of Civil and Geological Engineering, University
of Saskatchewan, 57 Campus Drive, Saskatoon, SK, Canada, S7N 5A9
Three sedimentary rocks are important volumetrically. They are:
MUDSTONE(shale), SANDSTONE, and LIMESTONE. These very common
rocks contain a very limited set of 5 or 6 minerals:
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