Petrology
The study of rocks, their
occurrence, composition, and origin. Petrography is concerned primarily with the
detailed description and classification of rocks, whereas petrology deals
primarily with rock formation, or petrogenesis. Experimental petrology
reproduces in the laboratory the conditions of high pressure and temperature
which existed at various depths in the Earth where minerals and rocks were
formed. A petrological description includes definition of the unit in which the
rock occurs, its attitude and structure, its mineralogy and chemical
composition, and conclusions regarding its origin. For a discussion of mineral
identification, petrographic analysis, and the classification of rocks See also: Mineralogy; Petrography; Rock
Igneous
rocks
Volcanic rocks are igneous rocks
that reach the Earth's surface before solidification. They occur as lavas or as
pyroclastic (fragmental) rocks.
Volcanic activity varies greatly in
intensity, duration, periods between eruptions, and quantities of gases, liquid
rock, and solidified fragments expelled. The important factors influencing these
differences are chemical composition of the magma; amount of gas dissolved in
it; extent of crystallization or cooling before eruption; and configuration of
the conduit and depth to the magma chamber. See also: Magma
Volcanic structures are of a variety
of types (Table 1), influenced by the style of activity of the volcano. Volcanic
rocks are presently forming mostly at plate boundaries: at the midocean ridges
where voluminous basalts are produced and at convergent plate boundaries (island
arcs and continental margins) where most explosive and more silicic volcanism
occurs. See also: Volcano
Intrusive igneous rocks occur in
many different types of units or intrusive masses, which are classified chiefly
by their shape and structural relations to their wall rocks (Table 2). Bodies
that crystallize at great depths (such as batholiths) are referred to as
plutonic; those consolidated under shallow cover are designated as
hypabyssal. See also: Pluton
The crystallization of the larger
intrusives may result in profound alterations in the adjacent wall rocks
(exomorphism). Where stocks and batholiths have invaded sedimentary rocks, an
aureole of contact metamorphism is developed. This results from
recrystallization under increased temperature and may be accompanied by chemical
transformations (pyrometasomatism) produced by hydrothermal solutions generated
during the latter stages of magmatic differentiation. Where batholiths have been
intruded into rocks which are already regionally metamorphosed, the contact
rocks formed are injection gneisses or migmatites. See also: Contact aureole
Igneous rocks make room for
themselves by forceful injection (dilatance), by engulfing wall rock blocks
(magmatic stoping), or by subsidence of overlying rocks. The hypothesis of
granitization maintains that granites result from the wholesale transformation
of sedimentary or metamorphic rock layers by solutions operating through mineral
replacement or by ionic emanations acting through solid diffusion.
Blocks of wall rock included in an
intrusive mass are xenoliths; their partial destruction by reaction may produce
irregular clumps of mafic minerals called schlieren. In some instances such
endomorphic effects are sufficiently intensive to result in modification of the
composition of the magma (syntexis).
See also: Xenolith
Crystallizing under equilibrium
conditions, early magmatic minerals react with remaining fluid to yield new
species (Fig. 1). Interruption of the sequence will yield liquid fractions
richer in silicon dioxide, alkalis, iron, and water than the original magma, and
crystalline fractions richer in calcium and magnesium than the parent magma
(magmatic differentiation).
Fig. 1 Reaction series of Bowen
(modified).
Igneous rocks occur in distinct
associations (Table 3) which can be put in a specific tectonic context. The
sources of magma are the mantle and lower crust of the Earth. The diversity of
magmas is caused by variations in the source rock, variations in the conditions
and depth of origin, differentiation at various depths, assimilation of other
rocks by the magma, mixing of two magmas which originated separately, and
unmixing (immiscibility) of the melt. A scheme which shows the possible
complexity of the origin of common igneous rock associations is given in Table
4. See also: Igneous rocks
Sedimentary
rocks
Sedimentary rocks are broadly
divided into two classes: clastic sediments, such as sandstones and
conglomerates, which are composed largely of fragments of preexisting rocks and
minerals and chemical sediments, such as evaporites and many limestones, which
form as chemical precipitates from oceans or lakes. With the exception of
material deposited by glaciers (till or the consolidated form tillite),
sedimentary rocks show bedding or stratification. This separation into generally
parallel layers (beds, strata) results from sorting according to grain size
during deposition, from differences in composition or texture, or from
variations in the rate of deposition. The development of most clastic sediments
proceeds in the following stages: There is a source rock, any older rock or, for
organic sediments, a supply of organically originated material. By weathering,
the older rock is mechanically comminuted, chemically altered, or both, to form
unconsolidated surficial rock debris called mantle. Particles are transported by
streams, ocean and lake currents, wind, glaciers, or by the direct action of
gravity which causes particles to slide and roll down slopes. Material moved by
rolling, suspension, or solution is deposited. Deposits usually are consolidated
by the processes of cementation (sandstones), compaction (shales), and
recrystallization (limestones).
Chemical changes accompanying
consolidation are termed diagenetic. Weathered material not transported may
become a residual sedimentary rock (bauxite). Sedimentary rocks are deposited
either on land areas (continental) or in ocean waters (marine). Most marine
sedimentation takes place on the submarine extensions of the continents called
continental shelves. Examples of types of sedimentary deposits are listed in
Table 5. Features characteristically found in sedimentary rocks, in addition to
stratification, are cross-bedding, concretions, ripple marks, mud cracks, and
fossils. See also: Diagenesis;
Sedimentology; Weathering processes
A formation, which is the basic unit
of stratigraphy, is a series of rocks deposited during a specific unit of
geologic time and consisting either of a particular rock type or of several
types deposited in a sedimentary cycle. Such a cycle is the changing sequence of
deposits reflecting, for example, advance or retreat of marine waters in a
particular area.
However, while sandstone may be
deposited at one time in one place in the sedimentary basin, limestone may be
formed simultaneously elsewhere. Such lateral variation in a formation is
referred to as facies. See also:
Cyclothem; Facies (geology); Stratigraphy
By means of detailed studies of the
fossils of a formation and its lithology, composition, structure, and
distribution, the paleoecology of the area may be reconstructed. Correlation of
formations is attempted chiefly on the basis of fossils, with supplementary data
from the lithology, stratigraphic position, insoluble residues (in acid-soluble
rocks), heavy detrital minerals (in clastic rocks) and in drill holes by
electrical conductivity, radioactivity, and seismic-wave velocities. See also: Sedimentary rocks
Metamorphic
rocks
Metamorphism transforms rocks
through combinations of the factors of heat, hydrostatic pressure (load), stress
(directed pressure), and solutions. Most of the changes are in texture or
mineral composition; major changes in chemical composition are called
metasomatism. The major types of metamorphism are presented in Table 6. Rocks
that can serve as parent material for metamorphic derivatives include igneous,
sedimentary, and older metamorphic rocks as well. The complexity of the possible
metamorphic mineral assemblages stems not only from the variety of possible
parent rocks and from the imposition of the several kinds of metamorphism but
also from variation in the intensity of particular types of metamorphism
(grade), and from the difficulty of readily achieving chemical equilibrium
through solid-state reactions. Various features characteristic of metamorphic
rocks include foliation (slaty cleavage, schistosity, and gneissic structure),
lineation, banding, and relict structures.
See also: Metamorphism; Metasomatism
The facies principle is employed in
attempting to reconstruct the environment under which a metamorphic rock was
developed. A metamorphic facies consists of all rocks, without respect to
chemical composition, that have been recrystallized under equilibrium, within a
particular environment of stress, temperature, load, and solutions. The first
two factors are considered critical. The facies are named after metamorphic
rocks deemed diagnostic of such restricted conditions. In practice, a group of
related rocks of different compositions is assigned to a particular facies upon
presence of such a key assemblage. Facies and their type descriptions are as
follows:
I. Facies of contact metamorphism.
Load pressure low, generally 100–3000 bars (10–300 megapascals). Water pressure
highly variable, in some cases possibly exceeding load pressure, in a few cases
very low. Facies listed in order of increasing temperature for given range of
pressure conditions.
Albite-epidote hornfels.
Hornblende hornfels.
Pyroxene hornfels.
Sanidinite—corresponds to minimum
pressures (load, PH2O, PCO2) and maximum
temperatures—pyrometamorphism.
II. Facies of regional metamorphism.
Load and water pressures generally equal and high (3000–12,000 bars or 300–1200
MPa). Facies listed in order of increasing temperature and pressure.
Zeolite (very low grade).
Prehnite-pumpellyite (very low
grade).
Greenschist (low grade).
Quartz-albite-muscovite-chlorite.
Quartz-albite-epidote-biotite.
Quartz-albite-epidote-almandine.
Glaucophane schist (represents a
divergent line of metamorphism conditioned by development of unusually high
pressures at low temperatures).
Almandine amphibolite (medium to
high grade).
Staurolite-quartz.
Kyanite-muscovite-quartz.
Sillimanite-almandine.
Granulite (high grade).
Hornblende granulite.
Pyroxene
granulite.
Eclogite (very high
pressure).
Because experimental petrology has
allowed the development of a “petrogenetic grid” of mineral reactions, most
facies may be subdivided if mineral assemblages are carefully detailed. This
subdivision can allow inference of pressure-temperature conditions of
metamorphism.
Regional variations in grade may be
mapped by means of isograds, lines formed by the intersection of planes of
isometamorphic intensity with the Earth's surface. These are defined on the
appearance of a specific mineral known to reflect a major increase in the
intensity of metamorphism.
The primary cause of stresses acting
during regional metamorphism is diastrophism of the mountain-building type.
These stresses may precede, accompany, or follow the heating, and the order of
thermal and structural events can be unraveled by petrographic study. Most
regional metamorphic rocks record several heating and deformation episodes. The
higher temperatures may result from deep burial, owing to the geothermal
gradient of the Earth, in part to concentrations of radiogenic heat, or in part
to heat supplied by cooling masses of magma. In contact metamorphism this last
is the sole heat source. See also:
Geologic thermometry
William Ingersoll Rose, Jr.
Experimental mineralogy and
petrology
One aim of mineralogy and petrology
is to decipher the history of igneous and metamorphic rocks. Detailed study of
the field geology, the structures, the petrography, the mineralogy, and the
geochemistry of the rocks is used as a basis for hypotheses of origin. The
conditions at depth within the Earth's crust and mantle, the processes occurring
at depth, and the whole history of rocks once deeply buried are deduced from the
study of rocks now exposed at the Earth's surface. One approach used to test
hypotheses so developed is experimental petrology; the term experimental
minerals refers to similar studies involving minerals rather than rocks (mineral
aggregates).
The experimental petrologist
reproduces in the laboratory the conditions of high pressure and high
temperature encountered at various depths within the Earth's crust and mantle
where the minerals and rocks were formed. By suitable selection of materials the
petrologist studies the chemical reactions that actually occur under these
conditions and attempts to relate these to the processes involved in
petrogenesis.
The experiments may deal with the
stability range of minerals and rocks in terms of pressure and temperature; with
the conditions of melting of minerals and rocks; or with the physical properties
or physical chemistry of minerals, rocks, and rock melts (magmas), or of the
vapors, gases, and solutions coexisting with the solid or molten materials.
These experiments may thus be related to major geological processes involved in
the evolution of the Earth: the conditions of formation of magmas in the mantle
and crust and their subsequent crystallization either as intrusions or lava
flows; the evolvement of gases by the magmas during their crystallization and
the precipitation of ore deposits from some of them; the processes leading to
the development of volcanic arcs and mountain ranges; and the metamorphism and
deformation of the rocks in the mountain chains, and thus the origin and
development of the continents. Representative experimental results are shown in
Fig. 2.
Fig. 2 Selected results in experimental
mineralogy and petrology, averaged from many sources. The two geotherms show the
temperature distribution with depth in the Earth. The solidus for dry basalt and
peridotite provides the upper temperature limit for magma generation to occur in
the mantle. The mineral facies of a peridotite upper mantle are shown below the
solidus. The lower limit for magma generation is given by the curve granite-H2O.
Solid-solid mineral transitions and reactions plotted are quartz-coesite, the
breakdown of albite, calcite-aragonite, and the polymorphic transitions among
kyanite-andalusite-sillimanite. A decarbonation reaction is shown by the curve
for MgCO3 (magnesite), and dehydration reactions are shown for serpentine, for
the assemblage muscovite + quartz, and for hornblende in mafic or ultramafic
rocks. Note the effect of pressure on the hornblende reaction in the
garnet-peridotite facies. 1 kilobar = 102 megapascals; °F = (°C × 1.8) +
32.
Experimental probes into the
Earth
The pioneer work of James Hall of
Edinburgh on rocks and minerals sealed within gun barrels at high pressures and
temperatures earned him the title “father of experimental petrology.” His
experiments, published early in the nineteenth century, heralded an era of
laboratory synthesis in mineralogy and petrology. Experimental petrology gained
tremendous impetus in 1904, when the Geophysical Laboratory was founded in
Washington, D.C., and new techniques were developed for the study of silicate
melts at carefully controlled temperatures. The results obtained by N. L. Bowen,
J. F. Schairer, and others have persuaded most petrologists that physicochemical
principles can be successfully applied to processes as complex as those
occurring within the Earth, and they have formed the basis for much of the work
performed at high temperatures and high pressures. The design of equipment
capable of maintaining high temperatures simultaneously with high pressures has
been successfully achieved only since about 1950, with a few notable exceptions.
The extent of the experimental probe into the Earth varies with the type of
apparatus used. The Tuttle cold-seal pressure vessel, or high-pressure test
tube, reproduces conditions at the base of the average continental crust.
Internally heated, hydrostatic pressure vessels reproduce conditions similar to
those just within the upper mantle. Opposed-anvil devices, or simple squeezers,
readily provide pressures of 200 kilobars or more, but temperatures attainable
are considerably lower than those existing at depths in the Earth corresponding
to these pressures.
The deepest experimental probe is
provided by a variety of internally heated opposed-anvil devices which can
produce pressures of 200 kbar (20 GPa) with simultaneous temperatures of 2000°C
(3630°F) or more, although the pressure and temperature measurements become less
accurate with the more extreme conditions. This deepest probe produces
conditions equivalent to depths of 180–240 mi (300–400 km) in the upper mantle,
which are not very deep compared with the 1740-mi (2900-km) depth at the core,
but are well within the Earth's outer 300 mi (500 km) where many petrological
processes have their origins. See
also: High-pressure mineral synthesis
Studies related to Earth
structure
Geophysical studies and inferences
about the compositions of deepseated rocks based on petrological studies of
rocks now exposed at the surface, together with laboratory measurements of
physical properties of selected materials, provide the basis for theories
concerning the composition of the Earth and those parts of the Earth which may
be treated as units. See also:
Earth interior
At high pressures, most silicate
minerals undergo phase transitions to denser polymorphs, and it is believed that
polymorphic transitions within the mantle contribute to the high gradients of
seismic-wave velocities occurring at certain depths. Experimental studies of the
olivine-spinel transition have been successfully correlated with the beginning
of the transition zone of the upper mantle at a depth of about 210 mi (350 km).
It has been widely held that the Mohorovičić (M) discontinuity marks a change in
chemical composition from basalt of the lower crust to peridotite of the upper
mantle, but recent experimental confirmation that basalt undergoes a phase
transition to eclogite, its dense chemical equivalent, suggests that the M
discontinuity could be a phase transition. This now appears to be unlikely for
several reasons, but more detailed experimental studies are required because
there remains a strong possibility that this phase transition is involved in
tectonically active regions of high heat flow where the M discontinuity is
poorly defined. See also: Moho
(Mohorovi^ ić discontinuity)
Igneous
petrology
The Earth's mantle transmits shear
waves and is therefore considered to be crystalline rather than liquid; but the
eruption of volcanoes at the Earth's surface confirms that melting temperatures
are reached at depth in the Earth from time to time and from place to place. One
group of experiments is therefore concerned with the determination of fusion
curves for minerals believed to exist in the Earth's mantle and of melting
intervals for mineral aggregates, or rocks. The position of the solidus curve
provides an upper temperature limit for the normal geotherm, and the experiments
dealing with melting intervals at various pressures have direct bearing on the
generation of basaltic magmas at various depths within the mantle. They also
provide insight into the processes of crystallization and fractionation of these
magmas during their ascent to the surface. This is one of the major problems of
igneous petrology. See also:
Igneous rocks; Magma
Many reactions among silicate
minerals are very sluggish, and the presence of water vapor under pressure
facilitates the experiments. Water is the most abundant volatile component of
the Earth, with carbon dioxide a poor second, and the water in the experiments
often plays a role as a component as well as a catalyst. In the presence of
water vapor under pressure, melting temperatures of silicate minerals and rocks
are markedly depressed, and curves for the beginning of the melting of rocks in
the presence of water provide lower limits for the generation of magmas. It is
widely believed that many of the granitic rocks constituting batholiths, the
cores of mountain ranges, were derived by processes of partial fusion of crustal
rocks in the presence of water. The hypothesis appears to be consistent with
experimental results on feldspars and quartz in the presence of water at
pressures up to 10 kbar (1 GPa) and with similar experiments on plutonic igneous
rock series ranging in composition from gabbro to granite. However, evidence
suggests that some magmas forming batholiths, and andesite lavas of equivalent
composition in tectonically active regions, originated directly from mantle
material. Experimental petrologists are therefore extending their studies of the
minerals and rocks to granitic and andesitic compositions to pressures greater
than 10 kbar (1 GPa), corresponding to upper mantle conditions, with and without
water present. See also: Silicate
phase equilibria
The path of crystallization of a
magma and the mineral reaction series thus produced are apparently quite
sensitive to many variables, including pressure, pressure or fugacity of water,
and oxygen fugacity. Techniques have been developed for studying the effect of
oxygen fugacity on crystallization paths and also for controlling oxygen
fugacity at very low values while the water pressure is simultaneously
maintained at very high values.
Metamorphic
petrology
When rocks are metamorphosed, they
recrystallize in response to changes in pressure, temperature, stress, and the
passage of solutions through the rock. The facies classification is an attempt
to group together rocks that have been subjected to similar pressures and
temperatures on the basis of their mineral parageneses. The metamorphic facies
are arranged in relative positions with respect to pressure (depth) and
temperature scales, and the experimental petrologist attempts to calibrate these
scales by delineating the stability fields of minerals and mineral assemblages
under known conditions in the laboratory. Potentially the most useful reactions
for this purpose are solid-solid reactions involving no gaseous phase, such as
the reactions among the polymorphs of Al2SiO5, kyanite, sillimanite, and
andalusite.
Progressive metamorphism of
sedimentary rocks produces a series of dehydration and decarbonation reactions
with progressive elimination of water and carbon dioxide from the original clay
minerals and carbonates. Experimental determination of these reactions, along
with the solid-solid reactions, provides a petrogenetic pressure-temperature
grid, in which mineral assemblages occupy pigeonholes bounded by specific
mineral reactions. If mineral assemblages in metamorphic rocks are matched with
the grid which has been calibrated in the laboratory, this provides estimates of
the depth and temperature of the rock during metamorphism. Unfortunately, the
temperatures of dissociation reactions are very sensitive to partial pressures
of the volatile component involved in the reaction, and therefore there are
complications introduced in application of the grid to metamorphic conditions.
However, continued experimental studies of the stability of minerals and mineral
stabilities under a wide range of laboratory conditions (in the presence of H2O
and CO2 gas mixtures, for example, and with oxygen fugacity varied as well) may
eventually provide a guide to the composition of the pore fluid that was present
during metamorphism. If this composition is known, then the experimental data
can be applied with greater confidence.
See also: Metamorphic rocks
Peter J. Wyllie
| Table 1: Types
of volcanic structure |
| Name |
Characteristics |
|
|
| Low height, broad area; formed by successive fluid
flows accumulating around a single, central
vent | |
|
|
| Cone of moderate size with apex truncated; circular in
plan, gently sloping slides; composed of pyroclastic particles, usually poorly
consolidated | |
|
|
| Small steep-sided cone with well-defined crater
composed of pyroclastic particles, well consolidated
(agglomerate) | |
|
|
| Composed of interlayered flows and pyroclastics; flows
from sides (flank flows) common, as are radial dike swarms; slightly concave in
profile, with central crater | |
|
|
| Basins of great size but relatively shallow; formed by
explosive decapitation of stratocones, collapse into underlying magma chamber,
or both | |
|
|
| Domal piles of viscous (usually rhyolitic) lava,
growing by subsurface accretion and accompanied by outer
fragmentation | |
| Cryptovolcanic
structures | |
| Circular areas of highly fractured rocks in regions
generally free of other structural disturbances; believed to have formed either
by subsurface explosions or sinking of cylindrical rock masses over magma
chambers | |
| Table
2: Characteristics of intrusive igneous rock masses |
| Name |
Shape |
Structural relations to wall rocks |
Size and other features |
|
|
|
|
| Few feet to hundreds of miles
long | |
|
|
|
|
| Up to several hundred feet
thick | |
|
|
| Plano-convex or doubly convex
lenses | |
|
| 1–4 mi (1.5–6.5 km) in diameter; several thousand feet
thick | |
|
|
|
|
| Few hundred feet to a mile in diameter; cores of eroded
volcanoes | |
|
|
| Irregular, with steep
walls | |
|
| A small batholith or its upward projection; outcrop
area less than 40 mi2(104
km2) | |
|
|
| Irregular, contacts dip steeply or outward; no bottoms
known | |
|
| Some cover 16,000 mi2(41,000
km2); some composite intrusives of varied
petrology | |
| |
|
| (2) Concordant in general, may be crosscutting in
detail | |
|
|
|
|
|
| Usually large; used as general name for intrusive
masses that do not fit other
definitions | |
| Table
3: Igneous rock associations |
| Name |
Main rock types |
Environment |
|
|
|
| Mid-ocean ridges, much of the ocean
floor | |
|
|
| Spilite, keratophyre, pillow
basalt | |
| Edges of island arcs; obducted ocean
floor | |
|
|
| Olivine basalt, trachyte,
phonolite | |
| Oceanic islands, atectonic continental
sites | |
|
|
|
| Isolated atectonic continental
sites | |
|
|
| Basalt (generally olivine-free),
diabase | |
| Continental flood basalt regions, associated with
rifting | |
|
|
| Gabbro, norite, anorthosite,
peridotite | |
| Continental rifting
sites | |
| Calc-alkalic volcanic
rocks | |
| Basalt, andesite,
rhyolite | |
| Convergent plate margins, island arc and continental
margin | |
|
|
|
| Convergent plate
boundaries | |
|
|
| Andesine or labradorite anorthosite, norite, syenite,
monzonite | |
| Domed pluton of massifs in Precambrian
terrains | |
|
|
| (a) Simple: granite,
granodiorite | |
| Precambrian shields; cores of
mountain | |
| |
| (b) Complex: gabbro, tonalite, granodiorite, minor
granite | |
|
|
|
| Granite (some alkalic), quartz syenite, syenite,
diorite | |
| Hypabyssal, in mountain ranges and as their
outliers | |
|
|
| Feldspathoidal rocks,
carbonatites | |
|
| |
|
|
|
|
| Minette, kersantite,
camptonite | |
|
| Table
5: Selected examples of sedimentary deposits under various
environments |
| Agent |
Deposit |
Resulting rock |
|
|
|
|
|
|
|
|
| |
|
|
| |
|
|
|
|
|
|
|
|
|
|
| |
|
|
|
|
|
|
|
|
|
|
| |
|
|
| |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| |
|
|
| |
|
|
|
|
|
|
| Breakers and alongshore
currents | |
|
|
| |
|
|
|
|
|
|
| |
|
|
|
|
| Reefs and other shell
deposits | |
|
| |
|
|
| |
|
|
|
|
|
|
| |
|
|
|
|
|
|
| |
|
| Manganese oxide
concretions | |
| |
|
|
| Table 6: Types
of metamorphism and their factors |
| Type |
Factors |
Changes in rock |
|
|
| Stress, low hydrostatic
pressure | |
| Fragmentation,
granulation | |
|
|
| Heat, low to moderate hydrostatic
pressure | |
| Recrystallization to new minerals or coarser grains;
rarely melting | |
|
|
| Heat, additive hydrothermal solutions, low to moderate
hydrostatic pressure | |
| Reconstitution to new minerals; change in rock
composition | |
|
|
| Heat, weak to strong stress, moderate to high
hydrostatic pressure, ± nonadditive solutions | |
| Recrystallization to new minerals or coarser grains;
parallel orientation of minerals to produce
foliation | |
Bibliography
T. F. W. Barth, Theoretical Petrology,
2d ed., 1962
M. G. Best, Igneous and Metamorphic
Petrology, 2d ed., 2007
K. Bucher and M. Frey, Petrogenesis of
Metamorphic Rocks, 7th ed., 2007
G. V. Chilinger, H. J. Bissel, and R. W.
Fairbridge (eds.), Carbonate Rocks, 2 vols., 1967
Y. Guegen and V. Palciauskas,
Introduction to Rock Physics, 1994
H. H. Hess and A. Poldervaart (eds.),
Basalts, 2 vols., 1967
A. Miyashiro, Metamorphic Petrology,
1994
A. Philpotts, Principles of Igneous and
Metamorphic Petrology, 1990
P. C. Ragland, Basic Analytical
Petrology, 1989
M. Wilson, Igneous Petrogenesis, 1988
J. D. Winter, Introduction to Igneous
and Metamorphic Petrology, 2001
Ali
fazeli=egeology.blogfa.com
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