39. Scientific errors that can result when myrmekite
and geologic evidence
Lorence G. Collins
April 18, 2001
The present studies of granitoid rocks from the
1980s into the year 2001 are
dominantly directed toward chemical analyses and experimental and theoretical
petrology rather than the determination of textures and petrography as seen in
thin sections. Values for chemical studies of the granitoids are that they (a)
support classifications into source types (S-I-A-M), (b) demonstrate liquid line
of descent toward the temperature minimum of the Ab-Or-Qtz system, (c) enable
the plotting of Harker diagrams of major oxides and spider diagrams of major and
trace elements to show differentiation trends, (d) serve to discriminate among
possible tectonic settings, and (e) provide data to enable the determination of
ages by using various isotopes (Winter, 2001). For most granitoids this method
of investigation is without reproach. However, when only chemical
studies are used to study a granitoid, many changes in the solidified magmatic
rocks may be hidden or unsuspected. Therefore, scientific errors in
interpretation can result.
Recent work suggests that where the granitoids
contain rim and/or wartlike
myrmekite, improper assumptions can be made concerning the complete history of
these rocks (Collins, Internet website articles, 1997-2001). Following
solidification, deformation and modification by fluids containing K and Si can
cause differentiation progressively toward the temperature minimum of the
Ab-Or-Qtz system. This occurs because recrystallized minerals in granitic rocks
formed by replacement processes below melting temperatures are stable there just
as those formed from a melt. Moreover, the elemental characteristics of their
primary magmatic sources and much of their physical features (e.g., enclaves,
dikes, zoning, hypidiomorphic textures) are inherited by the metasomatized rocks
so that internally and outwardly they retain much of their magmatic ancestry.
The chemical analyses can look the same (or nearly so) in both magmatic
or metasomatically altered granitoids, not only because of inheritance, but also
because the changes in chemical compositions during metasomatism parallel what
is observed in a liquid line of descent. It is only by analyzing textures, as
seen in thin sections, that extensive changes in chemistry and mineralogy can be
detected that are unrelated to magmatic processes. Understanding the
significance of myrmekite is important because its presence in a thin
section is an indication that additional study is needed in order to fully
comprehend what the chemical data mean (Collins, 1988a). The historical
background for the shift to modern styles of granitoid investigation and its
consequences are presented below as well as problems caused by sampling bias.
Because of these problems, guidelines for sampling granitoids are suggested.
An examination of articles published since
Michel-Lévy (1874) first
discovered myrmekite shows trends which illustrate progressive changes in
attitudes towards this unusual plagioclase-vermicular quartz intergrowth (see
references listed by decades). Becke (1908) was the first to propose that
myrmekite was formed by Na- and Ca- metasomatism of K-feldspar. Then, Schwantke
(1910) countered with the idea that myrmekite resulted from exsolution of Na,
Ca, Al, and Si from high temperature K-feldspar. Because of the conflict between
these two models, myrmekite became a subject of great research interest, and
investigators presented many arguments as to which one was correct. In the
1940s, 1950s, and later years, new kinds of myrmekite were described, having
different kinds of textural patterns and mineral relationships. Because some
textural patterns did not seem to be best explained by either of the above two
models for myrmekite origin, other models for myrmekite formation were
formulated. All of these early models were discussed and evaluated by Philips
(1974), but none had sufficient support to say that the origin of myrmekite had
In the 1940s through the 1960s, authors of
articles on granitic rocks and
gneisses commonly reported myrmekite in their petrographic descriptions, listing
it as an accessory or alteration mineral along with chlorite, sericite, epidote,
calcite, clay, iron oxides, apatite, allanite, titanite, and zircon. In this
same period, many authors also included discussions, indicating their favored
model for the origin of myrmekite. In the 1940s and 1950s, however, a great
debate raged about the origin of all granite bodies, as to whether
they were entirely formed (a) by subsolidus replacement processes of sedimentary
rocks ("granitization") or (b) by magmatic processes. See papers by Read,
Buddington, Grout, Goodspeed, and Bowen presented at a meeting of the Geological
Society of America held in Ottawa, Canada, December 30, 1947 (Gilluly, 1948).
The debate was subsequently won by the experimentalists, and their conclusion
that all granites of large size are magmatic in origin modified
opinions about myrmekite. If granite bodies were entirely magmatic in origin,
then myrmekite could only be a deuteric alteration mineral that was produced
during the final stages of crystallization of a magma. Moreover, because in the
1950s and 1960s, no definitive criteria had been developed to decide whether (a)
Ca- and Na-replacement of K-feldspar or (b) exsolution was the correct origin of
myrmekite, and because the presence of myrmekite did not seem to indicate any
important relationship affecting the petrology of the granite in a major way,
many authors of articles about granite in subsequent years no longer even
mentioned myrmekite nor promoted their preference for its origin. Myrmekite’s
tiny modal volume (generally less than 0.2 volume percent), its uncertain
origin, and its relegation to a mineral formed by alteration during the last
stages of crystallization of a magma seemed to suggest that myrmekite could be
ignored without any serious consequences.
On that basis, interest in myrmekite waned after
the 1960s, and the arguments
for magmatism as the primary origin of all granite were seemingly
so powerful that support for large-scale "granitization" also disappeared in
most educational institutions and geological surveys and in undergraduate
geology textbooks. Anyone supporting "granitization" was automatically regarded
as being "behind the times." Thereafter, experimental work on granitic melts and
chemical studies became the dominant accepted ways to investigate granites.
Petrography and textural analysis of the rocks, as obtained through studies of
microscopic thin sections, were relegated to the "trash heap," and editors of
journals were not interested in publishing such information. In place of thin
section studies, chemical analyses of major oxides and trace elements, and
theoretical and experimental petrology based on thermodynamics became the
dominant emphasis. Cathodoluminescent techniques, fluorescent x-ray, and
electron-microprobe methods of analysis soon replaced wet-chemical methods to
determine chemical compositions, and the addition of isotopic age-dating
methods, using various isotopes, became the accepted ways to study granitic
rocks (Winter, 2001).
On the basis of these modern methods of studying
granitic rocks, published
articles in the decades since the 1970s contain little mention of petrography.
Once it had been decided that all granites were magmatic in origin, the study of
petrography was no longer needed, and any hypothesis suggesting that not all
granites were totally magmatic in origin was not even considered. With this mind
set, many articles, describing the chemistry or isotopic compositions of
granitic rocks, mention only the main component minerals. No detailed
descriptions of textures occur, and the barest information about accessories or
alteration minerals is given, if at all. Even in other articles not emphasizing
chemistry, progressively through the decades since the 1960s, myrmekite commonly
is omitted from the petrography sections, even when it is relatively abundant.
This is in spite of the fact that other alteration minerals are reported. When
other alteration minerals are mentioned but not myrmekite, the lack of
noting myrmekite is an example of scientific negligence. All mineral
data, including myrmekite, should be reported when describing rocks even if the
authors do not regard myrmekite as being important.
In the 1960s and 1970s, research on myrmekite was
in limbo. Because it was
felt by editors of journals that myrmekite had been thoroughly studied, articles
on this topic were generally rejected. Even abstracts submitted for presentation
at professional conventions were rejected because the reviewers felt that
attendees would not be interested in them. However, many geologists were still
not satisfied with the then-available models for the origin of myrmekite, and,
surprisingly, a few articles proposing new models continued to appear in the
literature in the 1980s and 1990s as new kinds of myrmekitic textures were found
in different rock types. See the reference list by decades.
Beginning in 1972, my own work supported the
general feeling that all
large masses of granitic rocks have been emplaced by magmatic processes and that
no large granite mass has formed by subsolidus "granitization" of sedimentary
rocks. However, in the late 1970s, 1980s, and 1990s evidence became
available to me that some large plutonic igneous masses, after
emplacement and solidification, have been modified by K- and
Si-metasomatism to change them into rocks of a more-granitic composition, having
increasing percentages of K-feldspar and quartz (Collins, 1988a; Hunt et al.,
1992; Collins website articles at http://www.csun.edu/~vcgeo005). In
few places, even adjacent metasedimentary wall rocks had undergone similar and
simultaneous K- and Si-metasomatism as the magmatically emplaced pluton was
metasomatized. This metasomatism required deformation of solid
rocks below melting temperatures in order to create tiny fractures in
which fluids could enter and interact with the primary minerals in the rocks.
These fluids utilized local or outside sources of K and Si and removed some Ca,
Al, Fe, and Mg among other elements from the rocks. No migration of these
elements was by solid-state diffusion through undeformed rocks across vast
distances (meters and kilometers) as was assumed to occur by some geologists
during the old style "granitization" process. The only amount of
solid-state diffusion was on a scale much less than a millimeter and only
through half the diameter between closely-spaced, microscopic fractures within a
mineral grain. Significantly, the tiny fractures created by deformation
generally have gone unnoticed by petrologists because such brittle breakage of
plagioclase crystals cannot be seen in thin section under plane or
cross-polarized light. Only strong deformation that bends albite twin
lamellae or cataclasis that rotates broken fragments is observed under
cross-polarized light. Seeing these tiny fractures requires cathodoluminescence
imaging, which is a technique that petrologists have not commonly applied to the
study of granitic textures (Hopson and Ramseyer, 1990a; Collins, 1997b).
Consequently, these clues to the K-metasomatism have been missed. At any rate,
the main means of elemental migration must be in fluids moving through fractures
and by ionic diffusion through these fluids rather than by solid-state
diffusion. The residual effects of ion exchanges along the fractures during
these movements are readily seen in cathodoluminescent images.
Subsequently, the element identification along such fractures can be verified
with scanning- and electron-microprobe analyses (Collins, 1997b).
Resistance to this new K- and Si-metasomatic
model was enormous and
increasingly so after the 1970s to the year 2001 because the general feeling
among most granite petrologists is that "granitization" had been
disproved. K- and Si-metasomatism must have sounded like "granitization"
all over again, even though it was entirely different. Assumptions were made by
most petrologists that when a magmatically-emplaced granitic body became
crystallized, it was static, and, henceforth, it did not change (except by
weathering), even for billions of years. Therefore, any hypothesis suggesting
large-scale changes by metasomatic fluids was wrong. While agreeing with the
conclusion that all granitoids are emplaced and crystallized from magmas, I
suggested that the thin section evidence, field studies, and chemical analyses
(including electron-microprobe analyses) showed that large-scale K- and
Si-metasomatism is valid in some deformed plutonic masses, and myrmekite is the
clue to this metasomatism (Collins, 1988a). Nevertheless, the increasing
resistance to a model that sounded like "granitization" has continued in the
1970s, 1980s, and 1990s, regardless of the evidence that was provided.
Objection to large-scale K- and Si-metasomatism is
surprising for the
(1) Granite petrologists have already accepted
during fenitization (Winter, 2001), and the chemistry of Na is not much
different from that of K so that both should behave in the same way. Examples of
large-scale Na-metasomatism in granitic rocks are demonstrated in northern New
York (Collins, 1997r).
(2) Large-scale K-replacement of plagioclase
crystals (from the exterior
inward) is known to occur throughout some granitic plutons during late-stages of
the crystallization of the magma (Collins, 1997s). Therefore, lowering the
temperature just a few degrees below melting conditions should not change the
capability of K to replace plagioclase. However, the style of replacement
changes to that of replacing the plagioclase crystals from the interior outward
rather than from the exterior inward. The difference in style occurs because in
magma, not totally solidified, the ability of fluids to flow between
early-formed crystals creates space for the expanded, lower-density lattice of
K-feldspar to grow as it replaces the denser lattice of plagioclase. In
contrast, in completely crystallized granitoids, no expansion between sealed and
interlocking solid crystals can occur. First fracturing must occur, and then the
extra needed space for the K-feldspar lattice to form must be produced by
removal of elements from the interiors of the deformed plagioclase crystals. As
replacement occurs, it is not mass-for-mass, as in balanced chemical equations,
but volume-for-volume (Collins, 1988a, 1997a, 1997b).
(3) Experimental work of Orville (1962, 1963)
has already shown that
K-metasomatism can be demonstrated and that it occurs at rates that permit
the conversion of plutonic rocks containing plagioclase as the only feldspar
into granite containing K-feldspar during the geologic time frames that are
available (Collins, 1999b).
And finally, (4) economic geologists have observed
broad extent of
metasomatism by large quantities of introduced fluids to form many different
kinds of metallic ore deposits. Having seen the evidence for such great volumes
of "metal" replacements in deformed but solid rocks, our colleagues find it
surprising that granite petrologists do not accept large-scale
K-metasomatism (Tim H. Bell, email communication, 1997).
The problem for accepting large-scale K- and
Si-metasomatism to form
some granitoids is partly because granite petrologists have not seen the
evidence in thin section via cathodoluminescent imaging and because they have
been looking in the wrong places, as is suggested in the next section.
There is an anecdote about a person in the middle
of the night coming upon an
old man on his knees under a street lamp looking for his glasses. After learning
of the man’s loss, this person decides to help in the hunt. After several
minutes of looking, however, and finding nothing, this person asks: "Where did
you lose your glasses?" The old man points to the dark shadows and says: "Over
there." "Then, why are you looking here?" To which the man replied: "Because the
light is here."
This anecdote illustrates an analogous problem in
Myrmekite-bearing granitic rocks generally form resistant outcrops because of
the abundance of quartz and feldspars. The outcrops of granite ("where the light
is") stand above the valleys ("the shadows where the origin of myrmekite can be
found"). In this analogy the investigators of myrmekite have looked only in the
granite where the final product has been produced and not where the progressive
stages that led to the formation of the myrmekite have taken place. One must
look beyond the granite in the transition rocks where biotite is commonly
abundant to find the answer to the origin of myrmekite. Unfortunately,
biotite-rich rocks are easily weathered and eroded, and in many places glaciers
and streams have removed these weaker rocks, and vegetation, soil, and other
deposits cover them. Thus, natural processes force a sample bias on the person
wanting to collect rocks in a given terrain. Only the resistant rocks in outcrop
can be collected unless diamond drilling of covered rocks is used to obtain core
samples. Because of this limitation, in many places only the final product of
K- and Si-metasomatism can be collected, forcing an unfortunate sample bias.
Moreover, in many places the replacements and recrystallization of the original
rock found in the resistant outcrop have removed nearly all evidence for
its original composition and for its former deformation that permitted the K-
Another bias in sampling occurs because modern
studies of granites deal with
their chemistry and isotopic compositions. Rocks needed for these investigations
must be fresh, and only a few samples are required. When the investigator
already believes ("knows") that the granite is entirely magmatic in origin,
there is no purpose in collecting lots of samples to prove its magmatic origin,
and samples that might be weathered or messy are avoided. Two thin sections may
be sufficient to determine the main minerals. Yet, it is the abundance of
samples in the wall rocks and transitions to the granite and their thin sections
(the geologic evidence) that may reveal the true history of the
Guidelines for sampling granitoids
On that basis, to avoid sampling bias certain rules
should be followed when
collecting samples of granitic rocks.
1. The sampling must be systematic, making sure
that a grid distribution of
samples is obtained wherever the outcrops make it possible.
2. Even though the granitoid may appear to be
uniform (magmatic in
appearance), two samples need to be taken at each collection site in a grid in
order to see the local and broad variations that occur. Where a granitoid is not
uniform, all rock types should be collected at a given grid site.
3. Where foliation is present, strike and dip must
be measured, and the
sample that is collected must be taken from the same place that the rock
attitude is determined. The structural attitude of the sample relative to
attitudes of rocks in surrounding or adjacent areas may determine the sample’s
mineral and chemical composition because the composition may result from
metasomatic fluids moving into low pressure sites that are controlled by the
4. Exotic structures and textures (enclaves,
schlieren, etc.) are commonly
attractive, and the investigator must be careful in the field not to bias the
sampling by making a collection consisting of 80-90 percent of the exotic rocks
and 10-20 percent from the common rock type. The sampling should be proportional
to the relative volumes of the different rock types.
5. Efforts must be made to find and collect from
transition rocks. For
example, (a) if the granitic rock contains K-feldspar megacrysts, then
transitions to portions of the granitic body must be looked for in which the
megacrysts are absent. (b) If the K-feldspar megacrysts are zoned, then
transitions to places where they lack zoning must be sought. (c) If pegmatite
dikes are found, then the dikes need to be walked out along strike to see if
they grade into zones of deformation and then to where the dikes and deformation
disappear. And (d), similarly, if migmatites occur, the granitic portions need
to be sampled progressively along strike until the granitic rocks disappear.
Samples of these different kinds of transition rocks are likely to provide clues
to the evolutionary history of the granitoid.
Because myrmekite cannot be seen in the field, when
it is discovered later in
thin section, one should go back in the field, perhaps several times, to collect
additional samples and narrow down the transitions to where myrmekite first
appears. Because perthitic intergrowths also cannot be seen in the field, if the
albite lamellae in the K-feldspar are not uniformly distributed and are
irregular in size, then additional sampling is needed. If the perthite lamellae
have uniform distribution and are nearly constant in size, then they are likely
formed by exsolution from orthoclase. If the lamellae are not uniform, this
perthite could be formed from replacement of plagioclase by K-feldspar. Return
trips may also show progressive Si-replacements, producing interior quartz blebs
in hornblende and biotite across the transitions. At any rate, without such a
guideline to seek transition areas, these many different things to look for
might be missed if the investigator has preconceived notions that the granitoid
is entirely magmatic and unchanged since emplacement. As Goethe said: "We see
what we know."
Some of these sampling rules may go against one’s
natural tendencies in the
field. In some places great numbers of samples do not seem to be necessary. I
have had to remind myself many times to follow these rules when my instincts
said: "What is the use of sampling here?" However, the unaided eye can not see
mineralogical and textural changes that are important. Moreover, I discovered
that it was only when I collected hundreds of samples systematically and made
thin sections of these samples that structural attitudes at outcrops could be
tied to metasomatism. It was only when I collected 900 samples of amphibolite
and interlayered biotite-orthopyroxene-plagioclase (An80) gneiss in
eight different layers from noses to limbs in isoclinal folds did the thin
sections and other methods of analysis reveal convincing evidence for
progressive losses of iron from the ferromagnesian silicates in deformed
amphibolite in the limbs (Collins, 1969). These losses explained how magnetite
concentrations were formed in sufficient quantities to be mined as iron ore.
This same extensive sampling also showed the progressive changes in the limbs in
the deformed biotite-orthopyroxene-plagioclase gneisses to convert them into
myrmekite-bearing granitic gneisses. Likewise, in other terranes it has been
only when great numbers of samples were collected from areas outside a granite
body through transitions into the granite that I could observe the progressive
stages of myrmekite formation. See index of articles in the Internet URL: http://www.csun.edu/~vcgeo005/index.html
On the basis of the above, new attention needs to
be applied to thin section
studies of more than a few samples and to the occurrence and absence of
myrmekite in granitic rocks. Although granitic plutons are emplaced by magmatic
processes, that does not mean that these rocks will necessarily remain unchanged
through eons following their solidification. The constant stirring in the
mantle, causing crustal plate motions, must deform at least some of the
crystallized plutons, enabling metasomatic fluids to move through them. It is
agreed that using only petrographic studies of thin sections is inadequate to
explain what happens in the plutons during their entire evolutionary history.
But so also is a study limited to chemical analyses inadequate.
Investigators need to combine experimental, chemical, and theoretical studies
with geologic evidence obtained in the field and from detailed thin section
analysis, concomitant with cathodoluminescence studies, if scientific errors in
interpretation are to be avoided.
References by decades
- Michel-Lévy, A. M., 1874, Structure microscopique des roches
anciennes. Société Francaise de Mineralogie et de
- Crystallographie, Bulletin, v. 3, p. 201-222.
- Becke, F., 1908, Über myrmekit: Mineralogie und Petrographie
v. 27, p. 377-390.
- Schwantke, A., 1909, Die Beimischung von Ca in Kalifeldspat und die
Myrmekitbildung: Zentblatt für Mineralogie,
- p. 311-316.
- Eskola, P., 1914, On the petrology of the Orijarvi Region in south-western
Finland: Bulletin de la Commission geologique
- de Finlande, No. 40.
- Sederholm, J. J., 1916, On synantectic minerals and related phenomena:
Bulletin de la Commission geologique de Finlande,
- v. 9, p. 1-152.
- Anderson, A. L., 1934, Contact phenomena associated with the Cassia
batholith, Idaho: Journal of Geology, v. 42, p.
- Anderson, G. H., 1934, Pseudocataclastic texture of replacement origin in
igneous rocks: American Mineralogist, v. 19, p.
- Anderson, G. H., 1937, Granitization, albitization, and related phenomena
in the northern Inyo Range of California-Nevada:
- Geological Society of America Bulletin, v. 48, p. 1-74.
- Gilluly, J., 1931, Replacement origin of the biotite granite near Sparta,
Oregon: U.S. Geological Survey Professional
- Paper 175-C, p. 65-81.
- Hills, E.S., 1933, An unusual occurrence of myrmekite, and its
significance: Geological Magazine, v. 70, p. 294-301.
- Stark, J. T., 1935, Migmatites of the Sawatch Range, Colorado: Journal of
Geology, v. 43, p. 1-26.
- Anderson, A. L., 1942, Endomorphism of the Idaho Batholith: Geological
Society of America Bulletin, v. 53, p. 1099-1126.
- Anderson, A. L., Hammerand, V., 1940, Contact and endomorphic phenomena
associated with a part of the Idaho batholith:
- Journal of Geology, v. 48, p. 561-589.
- Bugge, J. A. W., 1943, Geological and petrological investigations in the
Kongsberg-Bamble Formation: Norges Geologiske
- Undersokelse Nr. 160, 150 p.
- Cheng, Y., 1944, The migmatite area around Bettyhill, Sutherland:
Quarterly Journal of the Geological Society of London,
- v. 99, p. 107-148.
- Drescher-Kaden, F. K., 1948, Die Feldspat-Quartz Reactions-gefuge der
Granite und ihre
- Genetische Bedeutung: Berlin, Springer-Verlag.
- Edelman, N., 1949, Microcline porphyroblasts with myrmekite rims: Bulletin
de la Commission geologique de Finlande No.
- 144, p. 73-79.
- Gault, H. R., 1945, Petrography, structure, and petrofabrics of the
Pinckneyville quartz diorite, Alabama: Geological Society
- of America Bulletin, v. 56, p. 181-246.
- Gilluly, J., (chairman), 1948, Origin of Granite, Conference at meeting of
the Geological Society of America held in Ottawa,
- Canada, December 30, 1947: Geological Society of America Memoir 28, 139 p.
- Gummer, W.K., 1941, Border rocks of a granite batholith, Red Lake,
Ontario: Journal of Geology, v. 49, p. 641-656.
- Hietanen, A., 1947, Archean geology of the Turku district in southwestern
Finland: Geological Society of America
- Bulletin, v. 58, p. 1019-1084.
- Krauskopf, K. B., 1943, The Wallowa batholith: American Journal of
Science, v. 241, p. 607-628.
- Pavlov, N. V., and Karskii, B. E., 1949, Myrmekite in basic rocks:
Ivestiya Akademii Nauk SSSR Seriya Geologisches-
- kaya, v. 5, p. 128. (In Russian)
- Perrin, R., 1949, On the granite problem: Journal of Geology, v. 57, p.
- Postel, A. W., 1940, Hydrothermal emplacement of granodiorite near
Philadelphia: Proceedings of the Academy of
- Natural Sciences of Philadelphia, v. 92, p. 123-152.
- Reynolds, D. L., 1943, The south-western end of the Newry igneous complex.
A contribution towards the petrogenesis of the
- granodiorite: Abstracts and Proceedings of the Geological Society of
London, no. 1396, p. 74-81.
- Reynolds, D. L., 1946, The sequence of geochemical changes leading to
granitization: Quarterly Journal of the
- Geological Society of London, v. 102, p. 389-446.
- Spencer, E., 1945, Myrmekite in graphic granite and in vein perthite:
Mineralogical Magazine, v. 27, p. 79-98.
- Waters, A. C., and Krauskopf, K., 1941, Protoclastic border of the
Colville batholith: Geological Society of America
- Bulletin, v. 52, p. 1355-1418.
- Wilson, A. F., 1947, The charnockitic and associated rocks of northwestern
south Australia, Part I, The Musgrave Ranges -
- an introductory account: Transactions of the Royal Society of South
Australia, v. 71, p. 195-211.
- Bowes, D. R., 1954, The transformation of tillite by migmatization at
Mount Fitton, South Australia: Quarterly Journal of
- the Geological Society of London, v. 109, p. 455-481.
- Harme, M., 1958, Examples of the granitization of plutonic rocks: Bulletin
de la Commission geologique de Finlande no.
- 184, p. 41-58.
- Kullerud, G., and Neumann, H., 1953, The temperature of granitization in
the Rendals-Vik area, northern Norway: Norsk
- Geologisk Tidsskrift, v. 32, p. 148-155.
- Parras, K., 1958, On the charnockites in the light of a highly metamorphic
rock complex in southwestern Finland: Geologinen
- Tutkimuslaitos, Bulletin de la Commission Geologique de Finlande, no.
- Perrin, R., 1954, Granitization, metamorphism, and volcanism: American
Journal of Science, v. 252, p. 449-465.
- Quensel, P., 1950, The charnockite series of the Varberg district on the
south-western coast of Sweden: Arkiv for Mineralogi
- och Geologi, Band 1, nr. 10, p. 227-322.
- Sarma, S. R., and Raja, N., 1958, Some observations on the myrmekite
structures in Hyderabad granites: Quarterly Journal
- of the Geological, Mineralogical, and Metallurgical Society of India, v.
30, p. 215-220.
- Sarma, S. R., and Raja, N., 1959, On myrmekite: Quarterly Journal of the
Geological, Mineralogical, and Metallurgical
- Society of India, v. 31, p. 127.
- Schermerhorn, L. J. G., 1956, The granites of Trancoso (Portugal): a study
in microclinization: American Journal
- of Science, v. 254, p. 329-348.
- Schreyer, W., 1958, Die Quarz-Feldspat-Gefüge der migmatischen
von Vilshofen an der Donan: Neues Jahrbuck für
- Mineralogie, Abhandlungen, v. 92, p. 147-170.
- Seitsaari, J., 1951, The schist belt northeast of Tampere in Finland:
Bulletin de la Commission geologique de Finlande,
- v. 153, p. 1-120.
- Skjeseth, S., and Sorensen, H., 1953, An example of granitization in the
central zone of the Caledonides of northern Norway:
- Norges Geologiske Underskelse, no. 184, p. 154-183.
- Surya Narayana, K. V., 1956, The nature of the potash feldspar in relation
to myrmekite in Clospet granites: Journal of
- Mysore University, v. 25, part 12, p. 97-106.
- Augustithis, S. S., 1962, Non-eutectic, graphic, micrographic and
graphic-like "myrmekitic" structures
- and intergrowths: Beitrage zur Mineralogie und Petrographie, v. 8, p.
- Burwash, R. A., and Krupicka, J., 1969, Cratonic reactivation in the
Precambrian basement of western Canada. Pt. 1,
- Deformation and chemistry: Canadian Journal of Earth Science, v. 6, p.
- Carman, J. H., and Tuttle, O. F., 1963, Experimental study bearing on the
origin of myrmekite (abstract): Geological
- Society of America Abstracts, Annual Meeting, p. 29A.
- Castle, R. O., 1966, Origin of myrmekite: Geological Society of America
Special Paper 87, (abstract), p. 198.
- Chatterjee, A. C., and Garg, N. K., 1968, Micropegmatite of myrmekite?:
Proceedings of the Indian Science Congress, p.
- Chatterjee, S. C., 1965, The anorthosites near Turkel in Kalahandi
District, Orissa, and the associated Khondalites
- and granite gneisses: D. M. Wadia Commerative Volume (Min. Geol. &
Met. Institute, India), p. 381-393.
- Collins, L. G., 1969, Regional recrystallization and the formation of
magnetite concentrations, Dover magnetite
- district, New Jersey: Economic Geology, v. 64, p. 17-33.
- Garg, N. K., 1967, Myrmekite in charnockite from southwest Nigeria: a
discussion: American Mineralogist, v. 52, p.
- Goodspeed, R. M., 1969, The origin of myrmekite in the Precambrian
plutonic granites in a portion of the New Jersey
- Highlands: Geological Society of America Abstracts with Programs, v. 1, p.
- Gore, D. J., 1968, Potash metasomatism and granitization accomplished by
boron-potassium compounds: International
- Geological Congress, 23rd, Prague, Proceedings, Section 4, p.
- Hietanen, A., 1962, Metasomatic metamorphism in western Clearwater County,
Idaho: U.S. Geological Survey Professional
- Paper 344-A, p. 1-116.
- Hofmann, A., 1967, Alkali infiltration metasomatism in feldspar solid
solutions: American Geophysical Union Transactions,
- v. 48, p. 230.
- Hubbard, F. H., 1966, Myrmekite in charnockite from southwest Nigeria:
American Mineralogist, v. 51, p. 762-773.
- Hubbard, F. H., 1967a, Myrmekite in charnockite from southwest Nigeria: a
reply: American Mineralogist, v. 52, p. 920-923.
- Hubbard, F. H., 1967b, Exsolution myrmekite; a proposed solid-state
transformation model: Geologiska Forenigens i
- Stockholm Forhandlingar, v. 89, p. 410-422.
- Hubbard, F. H., 1969, The proportionality of quartz in myrmekite: a
contribution to the discussion: American
- Mineralogist, v. 54, p. 988-989.
- Orville, P. M., 1962, Alkali metasomatism and feldspars: Norsk Geologisk
Tiddskrift, v. 42, p. 283-316.
- Orville, P. M., 1963, Alkali ion exchange between vapor and feldspar
phases: American Journal of Sciences, v. 261,
- p. 201-237.
- Phillips, E. R., 1964, Myrmekite and albite in some granites of the New
England Batholith, New South Wales: Journal of the
- Geological Society of Australia, v. 11, p. 49-59.
- Phillips, E. R., and Ransom, D. M., 1968, The proportionality of quartz in
myrmekite: American Mineralogist, v. 53,
- p. 1411-1413.
- Ramaswamy, A., and Murty, S., 1968, Myrmekite from pyroxene granulite:
Bulletin Geochemical Society of India,
- v. 3, p. 45-47.
- Ramberg, H., and Widenfalk, L., 1968, Bildning av myrmekit: Geologiska
Foereningen I Stockholm Foerhandlingar, v.
- 90, no. 534, p. 470.
- Ransom, D. M., and Phillips, E. R., 1969, The proportionality of quartz in
myrmekite: a reply: American Mineralogist,
- v. 54, p. 984-987.
- Rao, Y. J., and Raju, C. S., 1964, Diffusion through plagioclase feldspars
and its bearing on myrmekite formation: Current
- Science, v. 33, p. 307-309.
- Rao, Y. J., and Raju, C. S., 1969, Myrmekites in granitic rocks of
Srikakulam district, Andhra Pradesh: Current Science,
- v. 38.
- Sahu, K. N., 1968, On myrmekites of hypersthene granites of Tapang,
Orissa: Proceedings of the Indian Science Congress,
- p. 229.
- Sathe, R. V., 1964, A note on cotectic myrmekites from Jothwod granite,
Panchmahal District, Gujrat: Science and
- Culture, No. 30, p. 334-337.
- Schermerhorn, L. J. G., 1960, Telescoping of mineral facies in granites:
Bulletin de la Commission geologique de
- Finlande, No. 188, p. 121-132.
- Shelley, D., 1964, On myrmekite: American Mineralogist, 49, p. 41-52.
- Shelley, D., 1966, The significance of granophyric and myrmekitic textures
in the Lundy granites: Mineralogical Magazine,
- v. 35, p. 678-692.
- Shelley, D., 1967, Myrmekite and myrmekite-like intergrowths:
Mineralogical Magazine, v. 36, p. 491-503.
- Shelley, D., 1969, The proportionality of quartz in myrmekite: a
discussion: American Mineralogist, v. 54, p. 982-984.
- Siddhanta, S. K., and Akella, J., 1966, The origin of myrmekites in
hornblende-plagioclase gneisses and in the associated
- pegmatites: Acta Geologica Hungarica, v. 10, p. 31-52.
- Tufar, W., 1966, Bemerkenswerte Myrmekite aus Erzvorkommen vom
Alpen-Ostrand: Neues Jahrbuch für Mineralogie
- Monatshefte, v. 8, p. 246-252.
- Voll, G., 1960, New work on petrofabrics: Liverpool and Manchester
- Journal, v. 2, part 3, p. 503-567.
- Widenfalk, L., 1969, Electron micro-probe analyses of myrmekite
plagioclase and coexisting feldspars: Lithos, v. 2, p.
- Ashworth, J. R., 1972, Myrmekites of exsolution and replacement origin:
Geological Magazine, v. 109, p. 45-62.
- Ashworth, J. R., 1973, Myrmekites of exsolution and replacement origins: a
reply: Geological Magazine, v. 110,
- p. 77-80.
- Barker, D. S., 1970, Compositions of granophyre, myrmekite, and graphic
granite: Geological Society of America Bulletin, v.
- 84, p. 3339-3350.
- Bhattacharyya, C, 1971, Myrmekite from the charnockitic rocks of the
Eastern Ghats, India: Geological Magazine, v. 108, p.
- Bhattacharyya, C, 1972, Myrmekite from the charnockitic rocks of the
Eastern Ghats, India: a reply: Geological Magazine, v.
- 109, p. 371-372.
- Byerly, G. B., and Vogel, T. A., 1973, Origin of rimming, antiperthite and
myrmekite in metamorphic plagioclase
- (abstract): EOS, American Geophysical Union, Transactions, v. 54, no. 4,
- Carr, G. R., and Phillips, E. R., 1973, On exsolution myrmekite: Carstens,
H., 1967, Exsolution in ternary
- feldspars: II. Intergranular
precipitation in alkali feldspar containing calcium in
solid solution: Contributions to Mineralogy and Petrology, v. 14, p. 316-320.
- Didwal, R. S., 1970, On the origin of myrmekites in granitoid rock of Doda
district, Jammu & Kashmir State: Geoviews,
- v. VII, no 1, p. 13-20.
- Dusel-Bacon, C., 1979, Preliminary results of an augen gneiss study, Big
Delta quadrangle: U.S. Geological Survey Circular,
- v. 804 B, p. 57-59.
- Ghosh, D., 1976, On the myrmekites from the granite gneiss of Doranda,
Hazaribagh District, Bihar: Journal of the Geological
- Society of India, v. 17, no. 2, p. 201-206.
- Gupta, L. N., 1970, Evolution of myrmekites: Bulletin Indian Geologists’
Association, v. 3, p. 31-32.
- Hibbard, M. J., 1979, Myrmekite as a marker between preaqueous and
postaqueous phase saturation in granitic systems:
- Geological Society of America Bulletin, v. 90, Part I, p. 1047-1062.
- Hunter, D. B., 1976, On some potassium feldspars in the Precambrian
granitic rocks of Swaziland, v. 76, p. 63-73.
- Joergart, T., 1970, On the late formation of plagioclase in granitic
rocks: Dansk Geologisk Forening, Meddelelser, v. 20,
- no. 1, p. 69-71.
- Kazak, A. P., 1973, Problem of the origin and age of augen gneiss in the
Mediterranean basin: Doklady Akademii Nauk
- SSSR, v. 212, p. 1416-1419.
- Laurent, R., 1973, The origin and kinematic evolution of a metasomatic
granite of the Aiguilles Rouges, western Alps:
- Special Publication of the Geological Society of South Africa 3, p.
- Makhlayev, L. V., 1973, In reference to the genesis of myrmekites:
International Geology Reviews, v. 15, p. 179-182.
- Marmo, V., 1971, Granite petrology and the granite problem: Elsevier,
Amsterdam, 244 p.
- Myers, J. S., 1978, Formation of banded gneisses by deformation of igneous
rocks: Precambrian Research, v. 6,
- p. 43-64.
- Phillips, E. R., 1972a, Myrmekite from the charnockitic rocks of the
Eastern Ghats, India: a discussion: Geological
- Magazine, v. 109, p. 371.
- Phillips, E. R., 1972b, Compositions of granophyre, myrmekite, and graphic
granite: discussion: Geological Society
- of America Bulletin, v. 83, p. 249-250.
- Phillips, E. R., 1972c, Myrmekites of exsolution and replacement origins:
a discussion: Geological Magazine, v. 110,
- p. 74-77.
- Phillips, E. R., 1973, Myrmekites from the Haast schists, New Zealand: a
discussion: American Mineralogist, v. 58,
- p. 802-803.
- Phillips, E. R., 1974, Myrmekite - one hundred years later: Lithos, v. 7,
- Phillips, E. R., and Carr, G. R., 1973, Myrmekite associated with alkali
feldspar megacrysts in felsic rocks from
- New South Wales: Lithos, v. 6, p. 245-260.
- Phillips, E. R., and Ransom, D. M., 1970, Myrmekitic and non-myrmekitic
plagioclase compositions in gneisses from
- Broken Hill, New South Wales: Mineralogical Magazine, v. 37, p. 729-732.
- Phillips, E. R., Ransom, D. M., and Vernon, R. H., 1972, Myrmekite and
muscovite developed by retrograde metamorphism
- at Broken Hill, New South Wales: Mineralogical Magazine, v. 38, p.
- Phillips, E. R., and Stone, I. J., 1974, Reverse zoning between myrmekite
and albite in a quartzofeldspathic gneiss from
- Broken Hill, New South Wales: Geological Magazine, v. 39, p. 654-657.
- Ramaswamy, A., and Murty, S., 1972, Myrmekite from the charnockite series
of Amaravathi, Guntur district, Andhra
- Pradesh: Journal of the Geological Society of India, v. 13, p. 273-276.
- Robertson, I. D. M., 1978, Potash granites of the southern edge of the
Rhodesian craton and the northern granulite zone of
- the Limpopo mobile belt: Special Publication of the Geological Society of
South Africa 3,p. 265-276.
- Shelley, D., 1970, The origin of myrmekite intergrowths and a comparison
with rod-eutectics in metals: Mineralogical
- Magazine, v. 37, p. 674-681.
- Shul'diner, V. I., 1972, The problem of myrmekites: International Geology
Review, v. 14, p. 354-358.
- Shelley, D., 1973a, Myrmekites from the Haast schists, New Zealand:
American Mineralogist, v. 58, p. 332-338.
- Shelley, D., 1973b, Myrmekites from the Haast schists, New Zealand: a
reply: American Mineralogist, v. 58, p. 804.
- Ashworth, J. R., 1986, Myrmekite replacing albite in prograde
metamorphism: American Mineralogist, v. 71, p. 895-899.
- Chadha, D. K., 1980, On the formation of myrmekite in the Chaur
sub-foliated granite, Simla Hills, India: Recent Research
- in Geology (India), v. 6, p. 325-329.
- Collins, L. G., 1983, Myrmekite formed by recrystallization of plagioclase
and its implications for the origin
- of some granitic rocks: Geological Society of America Abstracts with
Program, v. 15, no. 5, p. 420.
- Collins, L. G., 1988a, Hydrothermal Differentiation And Myrmekite --- A
Clue To Many Geologic Puzzles: Theophrastus
- Publications S.A., Athens, Greece, 382 pp.
- Collins, L. G., 1988b, Myrmekite, a mystery solved near Temecula,
Riverside County, California. California
- Geology, v. 41, p. 276-281.
- Collins, L. G., 1989, Origin of the Isabella pluton and its enclaves, Kern
County, California: California Geology,
- v. 42, p. 53-59.
- Dymek, R. F., and Schiffries, C. M., 1987, Calcic myrmekite: possible
evidence for the involvement of water during the
- evolution of andesine anorthosite form St. Urbain, Quebec: Canadian
Mineralogist, v. 25, p. 291-319.
- Guha, D. B., and Gupta, L. N., 1986, Electron microscopic investigations
of perthite, myrmekite and rapakivi structures
- in feldspars occurring in the granitic rocks of the Doda area, Journal of
the Geological Society of India, v. 27, no. 2, p. 220-222.
- Heikal, M. A., Attawiya, M. Y., and El-Sheshtawi, Y. A., 1985, Textural
patterns, geochemistry and origin of the
- granitoid rocks around Wadi, El-Shiekh, southwestern Sinai, Egypt: Annals
of the Geological Survey of Egypt, v. 15, p. 197-210.
- Hibbard, M. J., 1980, Myrmekite as a marker between preaqueous and
postaqueous phase saturation in granitic systems:
- reply: Geological Society of America Bulletin, v. 91, Part I, p. 673-674.
- Hibbard, M. J., 1987, Deformation of incompletely crystallized magma
systems: Granitic gneisses and their tectonic
- implications: Journal of Geology, v. 95, p. 543-561.
- Hietanen, A., 1986, Role of replacement in the genesis of anorthosite in
the Boehls Butte area, Idaho: Bulletin of the
- Geological Society of Finland, v. 58, part 1, p. 71-79.
- Kresten, P., 1988, Granitization - fact or fiction?: Geologiska
Foreningens i Stockholm Forhandlingar, v. 100, pt. 4,
- p. 335-340.
- La Tour, T. E., 1987, Geochemical model for the symplectic formation of
myrmekite during amphibolite-grade progressive
- mylonitization of granite: Geological Society of America, Abstracts with
Programs, v. 19, p. 741.
- LaTour, T. E., and Barnett, R. L., 1987, Mineralogical changes
accompanying mylonitization in the Bitterroot dome of
- the Idaho batholith: implications for timing of deformation: Geological
Society of America Bulletin, v. 98, p. 356-363.
- La Tour, T. E., Thomson, M. L., 1988, Myrmekite as a transitional stage of
K-feldspar breakdown; in J. S. Kallend, J.
- S., and Gottstein, G., (eds.), Eighth International Conference on Textures
of Materials (ICOTOM 8): The Metallurgical Society, p. 817.
- Mehnert, K. R., 1987, The granitization problem - revisited: Fortschrift
Mineralogie, v. 65, p. 285-306.
- Moore, D. E., 1987, Syndeformational metamorphic myrmekite in granodiorite
of the Sierra Nevada, California: Geological
- Society of America Abstracts with Programs, v. 19 (7), p. 776.
- Nold, J. L., 1981, Myrmekite in metasedimentary rocks: Missouri Academy of
Science, Transactions, v. 15, p. 244.
- Nold, J. L., 1984, Myrmekite in Belt Supergroup metasedimentary rocks –
northeast border zone of the Idaho Batholith:
- American Mineralogist, v. 69, p. 1050-1052.
- Phillips, E. R., 1980a, On polygenetic myrmekite. Geological Magazine, v.
117, p. 29-36.
- Phillips, E. R., 1980b, Myrmekite as a marker between preaqueous and
postaqueous phase saturation in granitic systems:
- discussion: Geological Society of America Bulletin, Part I, v. 91, p.
- Rafiq, M., Khan, M. A., Jan, M.Q., 1988, Myrmekite in the Ambela granitic
complex, N. Pakestan; a product of deformation
- and replacement in the feldspars: Geological Bulletin, University of
Peshawar, v. 21, p. 159-165.
- Robertson, S., 1984, Textures of Archean granites, Ivisartoq region,
southern West Greenland: Report of activities
- 1983; Report – Geological Survey of Greenland, v. 120, p. 67-70.
- Schiffries, C. M., and Dymek, R. F., 1985, Calcic myrmekite in
anorthositic and gabbroic rocks: Geological Society of
- America Abstracts with Programs, v. 17, p. 709. (annual meeting in
- Simpson, C., 1985, Strain related myrmekitic intergrowths in mylonites:
Geological Association of Canada/Mineralogical
- Association of Canada, Programs with Abstracts, v. 10, p. A56.
- Simpson, C., 1985, Deformation of granitic rocks across the
brittle-ductile transition: Journal of Structural Geology,
- v.7, p. 503-511.
- Simpson, C., and Wintsch, R. P., 1989, Evidence for deformation-induced
K-feldspar replacement by myrmekite:
- Journal of Metamorphic Geology, v. 7, p. 261-275.
- Srivastava, D. K., and Karkare, S. G., 1987, Myrmekite in Bastar
granitoids and their genesis: Records of the
- Geological Society of India, v. 118, p. 74-75.
- Tadkod, M., 1989, Geochemistry of main rock types and petrogenesis of
myrmekite from Hells-Roaring Lakes area,
- Montana: Geological Society of America, 1989 annual meeting, Abstracts
with Programs, v. 21, no. 6, p. 276.
- Vidal, J. Kubin, L., Debat, P., and Soula, J., 1980, Deformation and
dynamic recrystallization of K-feldspar
- augen in orthogneiss from Montagne Noire, Occitania, southern France:
Lithos, v. 13, p. 247-255.
- Winchester, J. A., and Max, M. D., 1984, Element mobility associated with
syn-metamorphic shear zones near Scotchport,
- NW Mayo, Ireland: Journal of Metamorphic Geology, v. 2, p. 1-11.
- Yuezhi, C., 1980, The characteristics of myrmekite from the migmatites in
Huoqiu District, western Anhui: Geological Review
- (Dizhi Lunping), v. 26, no. 6, p. 499-504. (translation)
- Augustithis, S. S., 1990. Atlas Of Metamorphic-Metasomatic Textures And
Processes. Elsevier, Amsterdam, 228 pp.
- Brodie, K. H., 1995, The development of oriented symplectites during
deformation: Journal of Metamorphic Geology, v. 13,
- no. 4, p. 499-508.
- Collins, L. G., 1990, Cathodoluminescence microscopy of myrmekite:
Comment. Geology, v. 18, p. 1163.
- Collins, L. G., 1996, Metasomatic origin of the Cooma Complex in
southeastern Australia: Theophrastus’ Contributions
- to Advanced Studies in Geology, V. I, p. 105-112.
- Collins, L. G., 1997a, Origin of myrmekite and metasomatic granite:
Myrmekite, ISSN 1526-5757, electronic Internet
- publication, no. 1, http://www.csun.edu/~vcgeo005/revised1.htm.
- Collins, L. G., 1997b, Replacement of primary plagioclase by secondary
K-feldspar and myrmekite: Myrmekite, ISSN
- 1526-5757, electronic Internet publication, no. 2, http://www.csun.edu/~vcgeo005/revised2.htm.
- Collins, L. G., 1997c, Microscopic and megascopic relationships for
myrmekite-bearing granitic rocks formed by
- K-metasomatism: Myrmekite, ISSN 1526-5757, electronic Internet
publication, no. 3, http://www.csun.edu/~vcgeo005/revised3.htm.
- Collins, L. G., 1997d, Myrmekite formed by Ca-metasomatism: Myrmekite,
ISSN 1526-5757, electronic Internet
- publication, no. 4, http://www.csun.edu/~vcgeo005/revised4.htm.
- Collins, L. G., 1997e, Myrmekite formed by exsolution?: Myrmekite, ISSN
1526-5757, electronic Internet publication,
- no. 5, http://www.csun.edu/~vcgeo005/revised5.htm.
- Collins, L. G., 1997f, Myrmekite as a clue to metasomatism on a plutonic
scale; origin of some peraluminous granites:
- Myrmekite, ISSN 1526-5757, electronic Internet publication, no. 6, http://www.csun.edu/~vcgeo005/revised6.htm.
- Collins, L. G., 1997g, K-differentiation in magmatic and metasomatic
processes: Myrmekite, ISSN 1526-5757, electronic
- Internet publication, no. 7, http://www.csun.edu/~vcgeo005/revised7.htm.
- Collins, L. G., 1997h, Polonium halos and myrmekite in pegmatite and
granite: Myrmekite, ISSN 1526-5757, electronic
- Internet publication, no. 8, http://www.csun.edu/~vcgeo005/revised8.htm.
- Collins, L. G., 1997i, Large-scale K- and Si-metasomatism to form the
megacrystal quartz monzonite at Twentynine Palms,
- California, USA: Myrmekite, ISSN 1526-5757, electronic Internet
publication, no. 9, http://www.csun.edu/~vcgeo005/29palms.htm.
- Collins, L. G., 1997j, K- and Si-metasomatism in the Donegal granites of
northwest Ireland: Myrmekite, ISSN 1526-5757,
- electronic Internet publication, no. 10, http://www.csun.edu/~vcgeo005/donegal.htm.
- Collins, L. G., 1997k, Myrmekite in garnet-sillimanite-cordierite gneisses
and Al-Ti-Zr trends, Gold Butte, Nevada:
- Myrmekite, ISSN 1526-5757, electronic Internet publication, no. 11, http://www.csun.edu/~vcgeo005/gold.htm.
- Collins, L. G., 1997l, Myrmekite in the Santa Rosa mylonite zone, Palm
Springs, California: Myrmekite, ISSN 1526-5757,
- electronic Internet publication, no. 12, http://www.csun.edu/~vcgeo005/palm.htm.
- Collins, L. G., 1997m, Myrmekite in the Rubidoux Mountain leucogranite –
a replacement pluton: Myrmekite, ISSN
- 1526-5757, electronic Internet publication, no. 13, http://www.csun.edu/~vcgeo005/rubidoux.htm.
- Collins, L. G., 1997n, Myrmekite in muscovite-garnet granites in the
Mojave Desert, California, USA: Myrmekite,
- ISSN 1526-5757, electronic Internet publication, no. 14, http://www.csun.edu/~vcgeo005/mojave.htm.
- Collins, L. G., 1997o, Problems with the magmatic model for the origin of
the Hall Canyon muscovite granite pluton,
- Panamint Mountains, California, USA: Myrmekite, ISSN 1526-5757, electronic
Internet publication, no. 15, http://www.csun.edu/~vcgeo005/hall.htm.
- Collins, L. G., 1997p, Sericitization in the Skidoo pluton, California: A
possible end-stage of large-scale
- K-metasomatism: Myrmekite, ISSN 1526-5757, electronic Internet
publication, no. 16, http://www.csun.edu/~vcgeo005/skidoo.htm.
- Collins, L. G., 1997q, The mobility of iron, calcium, magnesium, and
aluminum during K- and Si-metasomatism: Myrmekite,
- ISSN 1526-5757, electronic Internet publication, no. 17, http://www.csun.edu/~vcgeo005/mobility.htm.
- Collins, L. G., 1997r, Sphene, myrmekite, and titanium immobility and
mobility; implications for large-scale
- K- and Na-metasomatism and the origin of magnetite concentrations:
Myrmekite, ISSN 1526-5757, electronic Internet publication, no. 18, http://www.csun.edu/~vcgeo005/sphene.htm.
- Collins, L. G., 1997s, Contrasting characteristics of magmatic and
metasomatic granites and the myth that granite plutons
- can be only magmatic: Myrmekite, ISSN 1526-5757, electronic Internet
publication, no. 19, http://www.csun.edu/~vcgeo005/myth.htm.
- Collins, L. G., 1997t, Failure of the exsolution silica-pump model for the
origin of myrmekite: Examination of
- K-feldspar crystals in the Sharpners Pond tonalite, Massachusetts:
Myrmekite, ISSN 1526-5757, electronic Internet publication, no. 20, http://www.csun.edu/~vcgeo005/pump.htm.
- Collins, L. G., 1997u, Three challenging outcrops in the Marlboro
Formation, Massachusetts, USA: Myrmekite, ISSN
- 1526-5757, electronic Internet publication, no. 21, http://www.csun.edu/~vcgeo005/three.htm.
- Collins, L. G., 1997v, K-feldspar augen in the Ponaganset gneiss and
Scituate granite gneiss, Rhode Island,
- Connecticut, and Massachusetts, USA: Myrmekite, ISSN 1526-5757, electronic
Internet publication, no. 22, http://www.csun.edu/~vcgeo005/augen.htm.
- Collins, L. G., 1997w, A close scrutiny of the "Newer Granites" of the
Caledonian Orogen in Scotland: Myrmekite,
- ISSN 1526-5757, electronic Internet publication, no. 23, http://www.csun.edu/~vcgeo005/scotland.htm.
- Collins, L. G., 1997x, Magmatic resorption versus subsolidus metasomatism
– two different styles of K-feldspar replacement
- of plagioclase: Myrmekite, ISSN 1526-5757, electronic Internet
publication, no. 24, http://www.csun.edu/~vcgeo005/ajo.html.
- Collins, L. G., 1997y, Muscovite-garnet granites in the Mojave Desert:
Relation to crustal structure of the Cretaceous
- arc: Comment: Geology, v. 25, p. 187.
- Collins, L. G., 1998a, The microcline-orthoclase controversy – can
microcline be primary?: Myrmekite, ISSN 1526-5757,
- electronic Internet publication, no. 26, http://www.csun.edu/~vcgeo005/primary.htm.
- Collins, L. G., 1998b, Metasomatic origin of the Cooma Complex in
southeastern Australia: Myrmekite, ISSN 1526-5757,
- electronic Internet publication, no. 27, http://www.csun.edu/~vcgeo005/cooma.htm.
- Collins, L. G., 1998c, Primary microcline and myrmekite formed during
progressive metamorphism and K-metasomatism
- of the Popple Hill gneiss, Grenville Lowlands, northwest New York, USA:
Myrmekite, ISSN 1526-5757, electronic Internet publication, no. 28, http://www.csun.edu/~vcgeo005/popple.htm.
- Collins, L. G., 1998d, The K-replacement modifications of the Kavala
megacrystal granodiorite and the Sithonia
- euhedral-epidote-bearing, hornblende-biotite granodiorite in northern
Greece: Myrmekite, ISSN 1526-5757, electronic Internet publication, no. 29, http://www.csun.edu/~vcgeo005/greece.htm.
- Collins, L. G., 1998e, The K-replacement origin for the megacrystal
Hermon-type granites in the Grenville Lowlands,
- northwestern Adirondack Mountains, New York, USA: Myrmekite, ISSN
1526-5757, electronic Internet publication, no. 30, http://www.csun.edu/~vcgeo005/hermon.htm.
- Collins, L. G., 1998f, The lateral secretion origin of Zn ores at Balmat
and Edwards, New York, USA: Myrmekite, ISSN
- 1526-5757, electronic Internet publication, no. 31, http://www.csun.edu/~vcgeo005/zinc.htm.
- Collins, L. G., 1998g, Exsolution vermicular perthite and myrmekitic
mesoperthite: Myrmekite, ISSN 1526-5757,
- electronic Internet publication, no. 32, http://www.csun.edu/~vcgeo005/perthite.htm.
- Collins, L. G., 1998h, Origin of the augen granite gneiss in the Bill
Williams Mountains, Arizona, USA: Myrmekite, ISSN
- 1526-5757, electronic Internet publication, no. 33, http://www.csun.edu/~vcgeo005/bill.htm.
- Collins, L. G., 1998i, Metasomatic aluminous gneisses at Gold Butte,
Nevada, U.S.A.; a clue to formation of strongly
- peraluminous granites; in Theophrastus’ Contributions To Advanced
Studies In Geology, Augustithis, S. S. and others (eds.), p. 33-46.
- Collins, L. G., and Behnia, P.,1998, Petrogenesis of the Ghooshchi Granite
by K- and Si-metasomatism of diorites and
- gabbros, western Azerbaijan, Iran: Myrmekite, ISSN 1526-5757, electronic
Internet publication, no. 25, http://www.csun.edu/~vcgeo005/iran.html.
- Collins, L. G., 1999a, The K-replacement origin of the megacrystal lower
Caribou Creek granodiorite and the Goat
- Canyon-Halifax Creeks quartz monzonite – modifications of a former
tonalite and diorite stock, British Columbia, Canada: Myrmekite, ISSN
1526-5757, electronic Internet publication, no. 34, http://www.csun.edu/~vcgeo005/caribou.htm.
- Collins, L. G., 1999b, Experimental studies demonstrating metasomatic
processes and their natural granitic environments:
- Myrmekite, ISSN 1526-5757, electronic Internet publication, no. 36, http://www.csun.edu/~vcgeo005/Orville.htm.
- Collins, L. G., 1999c, Overlooked experimental evidence for K-replacements
of plagioclase and origin of microcline in
- granite plutons: Myrmekite, ISSN 1526-5757, electronic Internet
publication, no. 37, http://www.csun.edu/~vcgeo005/Microcline.htm.
- Garcia, D., Pascal, M., and Roux, J., 1996, Hydrothermal replacement of
feldspars in igneous enclaves of the Velay
- granite and the genesis of myrmekites: European Journal of Mineralogy, v.
8, no. 4, p. 703-717.
- Hippertt, J. F., and Valarellie, J. V., 1998, Myrmekite constraints on the
available models and a new hypothesis for its
- formation: European Journal of Mineralogy, v. 10, nr. 2, p. 317-331.
- Hopson, R. F., 1991, Morphology and origin of wartlike myrmekite:
Geological Society of America Abstracts with Program,
- v. 23, no. 2, p. 36.
- Hopson, R. F., and Ramseyer, K., 1990a, Cathodoluminescence microscopy of
myrmekite: Geology, v. 18, p. 336-339.
- Hopson, R. F., and Ramseyer, K., 1990b, Cathodoluminescence microscopy of
myrmekite: Reply: Geology, v. 18, p. 1163-
- Hunt, C. W., Collins, L. G., and Skobelin, E. A., 1992: Expanding
Geospheres, Polar Publishing, Calgary, Canada,
- 421 pp.
- Jiashu, R., 1992, Origin of myrmekite: Acta Petrologica et Mineralogical
(Yanshi Kuangwuxue Zazhi), v. 11, no. 4, p.
- 324-330. (translation)
- Melis, E. A., and Williams, M. L., 1996, The development of gneissic
texture in a Proterozoic shear zone:
- Geological Society of America Northeastern Section, 31st Annual
Meeting, Abstracts with Programs, v. 28, no. 3, p. 80-81.
- Mathavan, V., 1997, The origin of myrmekites in the granitic rocks of
Ambegaspitiya, Sri Lanka: Journal of the
- Geological Society of India, v. 38, no. 3, p. 319-325.
- Moore, D. E., 1990, Flame perthite associated with faulting in
granodiorite, Mt. Abbott Quadrangle, California: AGU
- fall meeting, EOS, Transactions, American Geophysical Union, v. 71, no.
43, p. 1596.
- Rameshwar Rao, D., Sharma, K. K., and Choubey, V. N., 1990, Megacrysts in
the granitoid rocks of Wangta gneissic
- complex, Satluj Valley, Kinnaur District, Himachal Pradesh: in Group
Discussion on Suture zones, young and old: Seminar on Himalayan geology,
abstracts, p. 107. Wadia Institute Himalayan Geology, Dehra Dun, India.
- Stel, H., and Breedveld, M., 1990, Crystallographic orientation patterns
of myrmekitic quartz; a fabric memory in
- quartz ribbon-bearing gneisses: Journal of Structural Geology, v. 12, no.
1, p. 19-28.
- Vernon, R. H., 1990, K-feldspar augen in felsic gneisses and mylonites ---
deformed phenocrysts or porphyroblasts?:
- Geologiska Forenigens i Stockholm Forhandlingar, v. 112, p. 157-167.
- Vernon, R. H., 1991, Questions about myrmekite in deformed rocks: Journal
of Structural Geology, v. 13, no. 9, p.
- Vernon, R. H., 1998, Flame perthite and myrmekite in high grade
metapelitic gneisses at Cooma, Australia: EOS,
- Transactions, American Geophysical Union, v. 79, no. 17, p. 356-359.
- Vernon, R. H., 1999, Flame perthite in metapelitic gneisses at Cooma, SE
Australia: American Mineralogist, v. 84,
- p. 1760-1765.
- Zhao Wenhao, 1997, An interpretation of the origin of myrmekite under the
condition of granulite facies: Acta
- Petrologica et Mineralogical (Yanshi Kuangwuxue Zazhi), v. 16, no. 2, p.
- Collins, L. G., 2000, Modification of a magmatic tonalite to produce a
megacrystal granodiorite by K-metasomatism,
- Monterey peninsula and northern Santa Lucia Mountains, California, USA:
Myrmekite, ISSN 1526-5757, electronic Internet publication, no. 38, http://www.csun.edu/~vcgeo005/Monterey.html.
- Winter, J. D., 2001, An Introduction to Igneous and Metamorphic Petrology:
Prentice Hall, New Jersey, 697 p.
I thank my wife, Barbara, whose many
excellent suggestions greatly
improved this article. I also express my appreciation to David Liggett,
who has helped me with the technical computer problems for getting this
article and all the other articles on line for this electronic
For more information contact Lorence Collins at: firstname.lastname@example.org
Lorence G. Collins
Department of Geological Sciences
California State University Northridge
18111 Nordhoff Street
Northridge, California 91330-8266