++++ Met-Map NEWS #002 ++++
++++ 24 January 2002 ++++

To the Consultation Partners of the 'Constitution' of the Met-Map

Dear All,

First of all I would like to report that the Met-Map homepage has moved to a new place (with much shorter URL):
http://www.uni-tuebingen.de/geo/met-map/index.html

I have received numerous letters with over hundred comments and suggestions since the last (6th) version of the Constitution. The evaluation of them was not easy, thus I have to apologize about the delay of this letter and I ask sympathy from senders that I did not answer their letters from point-to-point. A part of suggestions is clearly opposite with the content of other ideas, another part of them became solved in the meantime. This letter presents a summary of the most debated points. Hereby I would like ask your comments to the unclear points, and in a form of voting we will find out the best solution. I know that this text is not short, and maybe boring and difficult to read, but I kindly ask all of you to contribute to the final decision of the unclear points. Keep in mind, please, that later we have to play by the rules which will be finalized in a democratic way only by us and by now.

In this formatted text the magenta bold indicates cited text and blue italics marks the places of voting.

Send your replies until 10th of February, please.
Use as simple format as possible (TXT, RTF or Word 2.0) to reduce the danger of transporting viruses.

Many thanks for your kind contribution,

Sincerely,

István Dunkl

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SYSTEM -- SPECIAL CHARACTERS WITH ACCENTS
        Yes, maybe the most painful point. This question affects nearly all countries. As it was anounced in Met-Map News #1 (see homepage: "History") the appearance of the special characters depends on the setting of the user's machine. If we put the Authors & geographic names using 'CE' character set and the user has not installed this kind of font the appearing text could be rather misleading. Thus, at the moment I can only support the pragmatic and feasible opinion of the Romanian National Coordinator, who evidently declared:

Citation >>>> For the Romanian topographic names we can use the "nude English". At the end of the work we can include a special vocabulary with the correct national terms and the English standard pronouncing. <<<<

VOTING #1:
____use "nude English" transcription, create a Vocabulary
____type all the texts of the whole Met-Map system using 'CE' character sets and place on major web-pages a warning that its correct appearance can be expected only at this-and-that conditions (CAREFUL, it is not 100% sure that we can realize this possiblity !!!)
____I have another opinion: ____


DESCRIPTION -- NAMING OF UNITS
        It is suggested to keep some more strict rules in the naming of Units (at the moment geographic, petrographic, tectonic and chronstratigraphic names are present).

        It is true, and I have to apologize: what stands on the homepage at the moment is just an early proposal.

VOTING #2:
____the naming of the Units depends on the Authors and is basically unlimited (old, already introduced tectonostratigraphic names can also be applied)
____ give only geographic names (it means we will have a basically new naming system)


DESCRIPTION -- ABBREVIATION OF UNITS
        It is suggested to use only 3 characters (letters and numbers - and no symbols, like "-")

        I propose to accept it because such short abbreviations we can place on maps of any scales.

VOTING #3:
____ 3 characters
____ 5 characters


DESCRIPTION -- GEOGRAPHIC POSITION
        It is suggested to avoid geological terms and names in defining the position of the Unit.

        It is a very logic and considerable idea, I suggest to support it and I have already modified the example text.


DESCRIPTION -- COMPLEX METAMORPHIC EVOLUTION
        In case of a multiphase metamorphic history where to place the observations of the individual metamorphic events within the "Description"?

        I suggest to mention it in chapter "Lithology, Mineralogy, Metamorphic Grade" with coupling of geochronological data. The "Summary" should contain more interpretative text.

OTHER OPINIONS?____


DESCRIPTION -- TECTONICS
        It is suggested not to use the paragraph "Structural Evolution" separately from the "Structural Position".

        I suggest to keep the proposed paragraphs of the "Description" because the first paragraph deals with the tectonic and deformation history within the Unit and the second one the structural relation to the neighbouring Units.

VOTING #4:
____ keep as it is
____ delete paragraph "Structural Evolution" from the Description


DESCRIPTION -- STRUCTURAL EVOLUTION
        Citation: >>>> My suggestion is to present the structural data in a table-form (see attached example), and to avoid (if possible) long text description. This would allow us to have more clear and easy-to-read structural database that would tell us more about the relative chronology of structures (Column I), type of structures and their general orientation with respect to the present-day coordinates (Column II), kinematics (Column III), deformation-metamorphism relation (Column IV), the age (Column V) and related references (Column VI). In this way it would be fully compatible with the data from Thermobarometry and Geochronology that are also ease readable in table-form. Even in case where some of met-events described in former paragraphs would not have related structural information we could put "?" here. Even in that case this would be helpful and stimulative for future workers. ...

Relative chronology of deformation and metamorphism

Event	Structure	Kinematics	Metamorphism	Age	Reference
D1	foliation & N-S trending mineral and Mylonitic lineation	top-NE (compressional?) shearing	greenschist	ca. 115 Ma	.
D2	NE-trending and NW-trending tight folds; locally developed space clevage, NW-directed thrusts	top-NW thrusting	local pressure solution and crystallization	Post-Paleogene, Pre-Neogene	.

<<<<

        I think it is a feasible, good idea.

VOTING #5:
____ place such an example table into the "Example Description"
____do not consider this suggestion


MAIN MAP -- PROJECTION
        It is suggested to present the whole map in a new Lat-Long coordinate system. It would mean:
- A much easier placing of the objects according to their coordinates on a basically rectangular x-y projection. (But, would we really know the coordinates of the objects?)
- The parallel longitudes would make the map a bit unconventional and this would not be equal-area projection, and along the >1000 km long N-S extension the "deformation" is noticeable (stretching at north).
- The Met-Map will not contain much information about lithology, Mahel's map does and this map has identical projection with the 1976 map, thus these two would be excellent completary maps.
- It would be a huge work.

        I propose to keep the 1976 projection.

VOTING #6:
____ Old, 1976 projection
____ Lat-Long projection


MAIN MAPS -- METAMORPHIC GRADE AND MODE
        It is suggested to subdivide the metamorphism not according to the metamorphic facies, but rather according to Winkler (1967) and creating categories like ocean floor metamorphism or low grade metamorphism; and HP/LT type metamorphism instead of blueschist facies of metamorphism and eclogite facies of metamorphism.

        It is very difficult to judge, because until now I have not received opposition to the planned "facies concept". As it is a serious, conceptional question, vote, please.

VOTING #7:
____ keep the subdivision of metamorphic grade presented in Constitution v.6 (see also Legend v.4)
____ open a new discussion on this idea and ask who sent the above suggestion to formulate a complete concept on the proposed subdivision


MAIN MAP -- SUBDIVISION OF PRE-ALPINE METAMORPHIC "CYCLES"
        In the Alpine-Carpathian belt the Variscan and Pre-Variscan crustal fragments are sliced, disconnected, they suffered deformation and metamorphism up to amphibolite facies. To figure out a proper subdivision of the Pre-Alpine events we have to respect the tectonometamorphic considerations made by the Variscides of the European plate as this area is free of the above mentioned Alpine metamorphism. I have contacted Professor Franke in Giessen, briefly explained our activity and asked him for suggestions about the time boundaries of the (s.s.) Variscan period. The answer was very detailed and he warned us that the concept of tectonic "events" can be hardly applied both in small scale and in the scale of a whole, complex orogen. But, (I've argued) we need time boundaries to separate the major periods to present them somehow. His answer:

Citation: >>>> terminology depends on your definition of an event. If you include rift-drift, then the Variscan period goes back beyond 400 Ma. If you restrict the term to convergence, an upper age limit of c. 400 is ok, but don´t forget the ordovician story in N-Gondwana: it is the first evidence of convergence in the Variscan realm. <<<<

        I know, that we have already broad knowledge about the crustal fragments from Pre-Variscan time. But, I guess, the majority of this information is related to the formation & emplacement of protoliths and they only partly register details of Pre-Variscan metamorphism. Thus, from our point of view they are not so relevant.
        The question of the Pre-Variscan remnants is important and complex; its presentation would be better in textual form (in the Description) and by small map-inserts than in the Main map of 1 to 1 mio scale. The actual proposal for the Pre-Alpine map would be to present the following age categories (as background colors):
- no Pre-Alpine metamorphism (Gray)
- Pre-Variscan: >400 Ma
- Variscan 400-300 Ma
(- and maybe Permian, see next paragraph)

VOTING #8:
____I accept the subdivision of the Main map to Variscan and Pre-Variscan
____I propose to create more age categories (give time boundaries and argue, please):____


MAIN MAPS -- AGE BOUNDARY BETWEEN ALPINE AND PRE-ALPINE MAPS
        The Alpine Map may consider metamorphic events and intrusive rocks emplaced after
A) the compressional phases of the Variscan (s.s.) orogeny or
B) after the Permian extension-generated magmatism and metamorphism of high thermal gradient.

In case of A) the well documented Permian metamorphism of the Eastern Alps would be presented on the Pre-Alpine sheet. It is actually the request of the Austrian colleagues. If we remove this event from the Alpine sheet, the information would not be so dense and the map would be better readable. Somehow the Permian extension is a consequence of the Variscan orogeny and it would give the reasoning of such a decision.
        In this case I would propose the following age boundaries and background coloring:
245-160 Ma Triassic-Early Jurassic (Magenta)
160-110 Ma Late Jurassic-Early Cretaceous (Blue)
110-65 Ma Late Cretaceous (Green)
<65 Ma Tertiary (Yellow)

In case of B) we should argue for the splitting at around the Carboniferous/Permian boundary by the clear cessation of Variscan nappe stacking. It would mean that the Alpine map would be more crowded than the Pre-Alpine. Further, the continental rifting has no well detectable cessation at the Permian, this geodynamic situation remained during Triassic and culminated in the Jurassic rifting. If we place the Permo-Triassic event on the Alpine sheet we will avoid an artificial splitting of a long-lasting process.
        In this case I would propose the following age boundaries and background coloring:
290-210 Ma Permo-Triassic (Magenta)
210-160 Ma Early Jurassic (Deep Blue)
160-110 Ma Late Jurassic-Early Cretaceous (Blue)
110-65 Ma Late Cretaceous (Green)
<65 Ma Tertiary (Yellow)

VOTING #9:
____present the Permian metamorphism and intrusive bodies on the Pre-Alpine sheet
____present the Permian metamorphism and intrusive bodies on the Alpine sheet
____other idea:


MAIN MAPS -- AGE BOUNDARY IN TERTIARY
        It is suggested to distinguish two age categories during the Tertiary metamorphism.
Citation: >>>>
a) Early Paleogene (collisional)
b) Late Paleogene + Neogene (post-collisional) <<<<

        I basically agree with this idea (as it was already mentioned in Constitution v.6, see FAQ). The Paleogene and Neogene metamorphic events have different character, but I have doubts, whether we can really fill the Alpine Main Map with this content systematically and everywhere.

VOTING #10:
____I accept the proposal
____keep one Tertiary age category


MAIN MAPS -- SUBDIVISION OF AMPHIBOLITE FACIES
        The reflections are univocal by considering the splitting of the amphibolite facies into a higher and lower part. The suggested signatures were also welcomed:



Where such a subdivision is not performable, the ' = ' symbol for the general amphibolite facies can be applied.

But, the determination of the boundary is not evident.
Citation: >>>> ... but can we apply "st-in" and "sill-in" in metabasites?
I will prefer (...) epidote-amphibolite (as transition zone to greenschists especially in metabasites), amphibolite facies and higher parts of amphibolite facies (as transition to granulite facies or anatexis in suitable rock composition). <<<<

Other citation: >>>> I would prefer epidote amphibolite facies because even in those areas with minor petrology available it is an evident parameter you can distinguish in thin sections. (...)
St -in (...) a good criterion but not generally. More useful I would find the Sill-in or anatexis. <<<<

        I kindly ask everyone to send well-formulated suggestions to define splitting of the amphibolite facies. Consider, please, that at the first developing stage we will not place mineral in-out lines on the Main maps.
        We have to make a second turn of voting in this question later.

VOTING #11:
I would prefer the following definition:____


MAIN MAPS -- DISTINCTION OF ORTHO AND PARA ROCKS
        Citation:
>>>> In legend I suggest separations Para and ortho metamorphic rocks
...
In low grade of metamorphism separate metaclastic rocks from
metavolcanic rocks (i.e. illite crystallinity from zeolite, prehnite or
prehnite actiniolite facies)... <<<<

        Yes and no. I am afraid that the size of outcrops and the often variable composition of the metamorphic sequences make the realization of this idea on the 1 to 1million scaled Main Maps difficult because such formations can be mixed at small scale. But, there is no limit to place smaller, more detailed maps on the web-site with links to the Main Maps. Another point: in higher grade metamorphism this distinction is not always evident.
        However, in case of greater bodies with lower grade overprint, when the magmatic character and emplacement age are still detectable, it seems feasible to present them: see next paragraph.


MAIN MAPS -- MAGMATIC ROCKS
        This is one of the most debated issue. After many and long discussions it crystallized slowly, that the presentation of the intrusive bodies is necessary. Using this concept the only artificial boundary is the omission of the volcanic edifices. But, we have to do it as they are surface and shallow formations, and their life is more related to sedimentary environment than to the metamorphites.
        We plan to present the Variscan and Pre-Variscan intrusive bodies only on the Pre-Alpine sheet and they will not be distinguished on the Alpine sheet. (The Permian magmatites can be presented either on the Alpine or on the Pre-Alpine sheet, it depends on your voting, see other points). The intrusive rocks emplaced during the (Permian &) Mesozoic & Tertiary times will be on the Alpine sheet. The question is how to present their age, chemistry, and metamorphic overprint (if they have any)?
        If a volcanic formation is metamorphically overprinted it "becomes visible" for the Met-Map. The dilemma again: to present or not to present its origin (DISTINCTION OF ORTHO AND PARA ...?). My proposal is to distinguish the metavolcanic units, when:
1) they have big size (> 1-2 km, with generalization 2-3 mm on the Main map),
2) their protolith was formed during the discussed time period of the map (e.g. Pre-Permian in the "Pre-Alpine map" or Post-Carboniferous in the "Alpine map"; of course the exact boundary depends on the voting.....).

For the graphic presentation I suggest the following scheme:

Unmetamorphosed intrusive rocks:
Background color: white
Pattern:
        "L": ultrabasic and basic rocks
        "X": intermediate and acid rocks Character: age of emplacement (e.g. T: Triassic)
Color:
        green: ultrabasic and basic rocks
        red: intermediate and acid rocks

Metamorphosed magmatic rocks (inclusive metavolcanics!)
Background color: age of metamorphism
Pattern: degree of metamorphism
Character: age of emplacement (e.g. T: Triassic)
Color of character:
        green: ultrabasic and basic rocks
        red: intermediate and acid rocks

Some examples:
Jurassic ultrabasic or basic intrusive: (Maybe instead of "L" we can use "+" as a petrographic symbol which is not so letter-like?)


Eocene intermediate-acid intrusive:


Triassic basic metamagmatite, subgreenschist metamorphosed during Tertiary:
(WARNING: the background color may seems to be gray if your screen setting shows only 256 colors!)


Jurassic acid metamagmatite, greenschist facies metamorphosed during Late Cretaceous:


With the combinations of these patterns, colors and age symbols we will able to mix all possible combinations. I am afraid that we will not be able to distinguish basic-ultrabasic (etc.), because it would be difficult to introduce more colors and patterns - do not forget that several colors are already used as background and patterns are already showing metamorphic facies.
(The size, exact color and frequency of symbols are only preliminary.)

VOTING #12:
____ I accept the proposed scheme
____ I have another color-pattern scheme: ____
____do not present magmatites at all
____do not distinguish metavolcanic formations


MAIN MAPS -- PRESENTATION OF GEOLOGY AND METAMORPHIC FORMATIONS
        Many issues ask about the presentation of the nonmetamorphic cover. I would propose to apply the concept of the 1976 Map: If in a given point the metamorphic formations are on the surface than "exposed" coloring indicates them; if they are covered, than "subsurface" coloring indicates them - independently on the covering lithology, stratigraphy, thus Miocene Molasse and Mesozoic carbonate platform identical in this respect.

        Very many well mapped and important small areas can not be presented on a map of 1 to 1 mio scale. These delicate areas can be shown on detailed maps.

Citation: >>>>In an Alpine nappe stack, the arrangement of units is commonly vertical. In this way, some boundaries can remain open, or the metamorphic grade is inverted, or there are repetitions of units. <<<<

        In the Description you can present also profiles.


UNITS -- CONCEPT OF BOUNDARIES
        The heaviest and most vehement critics has arrived about the definition of Units. The opinions can be formulated in this way:
A) "orthodox-way": considering only the facts of metamorphic geology and geochronology and amalgamating all the neighbouring blocks if they have similar metamorphic evolution.

B) "Influenced by tectonic considerations and conventions": keeping in mind the earlier plate tectonic considerations and facies arrangements. If we follow this way we may inherit ideas and structures which are actually in contradiction with the metamorphic pattern.
        In this case we should extend the definition of Units:
Citation: >>>> The Boundaries are defined and separating Units of distinct metamorphic histories. Consider furthermore please, that this map - as far as possible - tries to take into account existing major tectonic features (eg. nappe boundaries, clearly proven first order tectonic zones ...) as well, which does not mean neccesarily (very) distinct metamorphic histories between two neighbouring structural blocks ... . However, the presentation of major structural features seems to be reasonable.<<<<

        Consider, please, at this decision that we are planning to develop a basically new communication structure. The Met-Map (hopefully) will be updated later and the boundaries (which are mainly pure interpretations) will be changed by dynamic reworking and by presentations of new, alternative ideas.

VOTING #13:
____ keep the definition of Units as it is in Constitution v. 6
____ paste the cited paragraph into the definition
____other suggestion for the definition: ____


PIN-BOARD ARTICLES
        It is planned to present your opinions, news, shorter or longer scientific communications (also with figures, tables) on the homepage. I do not plan any control on them, and the header of that web-page will contain: "Authors alone are responsible for the statements in their articles."

Citation: >>>> Is there a "life-time" for articles? I suggest that compilers or editors may erase "old articles" if new arguments arrived. Otherwise important contributions get lost in the mass of pages. <<<<

( He was very optimistic considering the mailing activity ;-) )

VOTING #14:
____ keep all article "forever", like in a journal: printed--> remains (exceptions can be found only in Orwell's 1984)
____delete the article when its Author asks for that
____delete, when the Editor considers it as "outdated"


COMPLETION OF THE FAQ AT THE END OF CONSTITUTION
        If you think some topics are need to be explained in a more detailed way for the users of the Met-Map, please do not hesitate to give suggestions and/or send formulated paragraphs to complete the "FAQ" of the Constitution.


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Thank you again for your kind contribution.

Sincerely,

István Dunkl