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.............................................................................................................................. SDS Minutes 2008 .............................................................................................................................. Minutes of the SDS Business Meeting Kitab
State Geological Reserve, 5.
Devonian Chronostratigraphic Definitions R.
Thomas Becker,
assisted by CM U. Jansen
(protocol) Apart
from TM Hladil
and the Chairman,
none of the present members and guests attended the Business Meeting at
Oslo. Consequently it was decided to go through the complete Agenda of
the Oslo Meeting, but giving special emphasis (and time) to the Emsian
discussion, the main reason for the Field Symposium. In order to allow
everybody to follow the discussion in all details, CM obut
offered a complete translation from English into Russian and reverse. The
following Minutes will not repeat all the information of the Oslo
Minutes. It will only concentrate on additional data and on the Emsian
discussion. Attendance:
The Chairman,
TMs J. Hladil,
N. Izokh,
J.I. Valenzuela-Rios;
CMs N. Bakharev,
P. Carls,
R. Feist,
U. Jansen,
A. Kim,
H. Matyja,
O. Obut,
L. Slavik;
guests S. Berkyova
(Prague), P. Cejchan
(Prague), C. Crônier
(Lille), K. De
Baets
(Zürich), C. Dojen
(Münster), I. Evdokinova
(St. Petersburg), M. Erina
(Tashkent), J. Fryda
(Prague), F. Karimova
(Tashkent), I.A. Kim
(Tashkent), V.G. Khromych
(Novosibirsk), L. Koptikova
(Prague), O. Mesentseva
(Novosibirsk), N. Meshchankina
(Tashkent), E.D. Michailova
(St. Petersburg), H.-G. Mittmeyer
(Schlangenbad, Germany), S V. Nikolaeva
(Moscow), U.D. Rakhmonov
(Kitab), O. Rodina
(Novosibirsk), F. Salimova
(Tashkent), M. Schemm-Gregory
(Frankfurt), G.D. Webster
(Pullman, Washington). Document:
Carls,
P., Slavik, L. & Valenzuela-Rios: Request and comments
concerning the GSSP for the basal Emsian stage boundary, 9 pp., 1 Fig. [see
SDS newsletter 23 (2009)]. The
Chairman
opened the SDS Business Meeting and expressed his warmest thanks to the
Uzbek hosts, notably to I.B. Turamuratov,
in his function as meeting Chairman, to N.G. Mavlyanov,
Chairman of the State Committee on Geology and Mineral Resources of
Uzbekistan (SCGMR Ruz), and to the Devonian team of Uzbekistan, with A. Kim,
U. Rakhmonov,
N. Meshchankina,
M. Erina,
and others. The present SDS members are overwhelmed by the Uzbek
hospitality, by the pleasant and comfortable set-up in the Kitab Reserve,
by the perfect organisation, the wonderful sections, and the beauty of
the nature. The outcrop quality and fossil content are amongst the best
on a global scale for the Lower Devonian and this ensures that many
Devonian workers will like to return to the area. The Chairman
emphasized the importance of the long Tashkent-Novosibirsk cooperation,
which enabled this meeting, which allowed the significant recent
research progress, and which is of highest importance for the solution
of the current problems of Emsian stratigraphy. Amongst many others,
special thanks is given to the unfortunately absent CM Yolkin,
to CM Bakharev,
TM Izokh,
and CM Obut.
The sometimes tiring translation service of Olga was very crucial for
the great success of the meeting and excursion. The oral presentations
included
many high-quality contributions that covered all of the Devonian
and many regions. There were almost 30 talks and 18 posters. It is
especially important that a wealth of new data for the Devonian of
Uzbekistan and of Russian regions have been made available to the
international scientific community. The Kitab Meeting will be long
remembered and will result in a lasting improvement of communication
between Devonian specialists and in true friendship between workers that
had not much previous contact. Independent from the outcome of the
Emsian revisions, there is the unanimous feeling that the excursion and
symposium of the last days has been a great success. All SDS members
that did not attend will have to regret that they missed the event. Stratigraphy
as a geoscience discipline suffers in general from the lack of a first
class journal with high international reputation and high impact factor.
In this respect the Chairman
draws attention to the re-juvenation of the “Newsletters on
Stratigraphy”, which, since early 2008 (or starting with vol. 43), has
the formal support of ICS and IUGS. The journal´s editorial board has
been broadened and the format enlarged. SDS members are recommended to
grab this improved publication opportunity. 5.
Devonian Chronostratigraphic Definitions 5.1.
Lochkovian The
Chairman
stated that he recognized that some workers started to use subdivisions
of the Lochkovian in publications. He asked whether there was a wish for
future formal subdivision. TM Valenzuela-Rios,
CM Carls
and C. Dojen
confirmed the use of three informal substages (lower, middle, upper). A
formal substage recognition seems possible but requires additional work. 5.2.
Pragian In
relation with the Emsian, a new Pragian discussion is inevitable. CM Slavik
explained the difficulties of the basal Pragian definition since Eognathodus
sulcatus, the traditional basal index taxon, is very rare in the
Barrandian and has been found 20 cm below the GSSP. Currently, the entry
of “Icriodus” steinachensis is used as approximation. M. Erina,
consequently, asked for a revision of the Pragian base. CM Carls
and Slavik
re-iterated the problem (see Document) that the current Emsian GSSP is
placing more than half of the type region Pragian (or Praha Limestone)
into the lower Emsian. In other words, the Pragian Stage has lost much
oft its distinction and duration. 5.3.
Emsian There
was a prolonged discussion concerning the base of the Emsian and its
substage subdivision. The long and free exchange of arguments, not
repeating here the Document statements, can be summarized as follows: CM
Carls:
The alleged 15.4 Ma duration of the Emsian in the absolute Kaufmann
scale needs to be critically evaluated by biostratigraphers. The current,
strongly shortened Pragian, between the Pragian and Kitab GSSPs, as well
as the interval between the latter and the traditional (German) Emsian
can be re-defined as new chronostratigraphic units (substages). CM
Bakharev:
A subdivision of the Emsian into three substages, keeping the Kitab GSSP,
should be considered. Endemism and strong facies control on
distributions characterize many brachiopods; this questions the
significance of the German Emsian brachiopod zonation in relation with
the conodont stratigraphy. The entry of Po. kitabicus works fine
in the Salair. CM
Jansen:
The Siegenian-Emsian brachiopod succession of the Emsian type region has
been long and well studied, especially the spiriferid phylogeny. It
allows correlations with other European regions (Spain) and to some
extent also with North Africa. It uses evolutionary changes, not
facies-controlled local occurrences. M.
Erina:
The entry of Po. kitabicus marks a very important step in early
polygnathid evolution, which was also emphasized in her oral
contribution. Therefore, the GSSP should stay where it is. TM
Valenzuela-Rios:
The Emsian revision requires a very careful restudy of the Zinzilban
conodonts, especially the entry of the Po. excavatus Group, which
includes several forms. Po. kitabicus provides a very important
and useful time marker, but not for the basal Emsian since it enters
much too early. Chairman:
GSSPs can and are often placed outside the traditional areas of
chronostratigraphic units (e.g., Givetian, Frasnian, Famennian) but they
should be close to the unit base in their classical type-region. The
meaning of a chronostratigraphic term should not change too much in a
type region since this would create great confusion. Without purpose,
this rule has been violated in the case of the Emsian. A future
subdivision of the Emsian into two substages has already been voted on
by SDS. A revised GSSP decision must take other fossil groups into
consideration, too. Statements are needed in which region the kitabicus
boundary has been successfully applied. As said before (SDS Newsletter
22), the appearance of true Icriodus or of the I. corniger
Group is a very useful level in Europe and North Africa to recognize an
Upper Emsian substage, also with the oldest anarcestids. Unfortunately,
the entry of Icriodus s.str. has not yet been correlated into
North America and Asia, mostly because of endemism in conodonts. CM
Carls:
The kitabicus level probably can be recognized in Nevada. TM
Hladil:
The gamma ray spectroscopy and magnetic susceptibility should be studied
in the GSSP section, as it has been in the Barrandian. The Czech group
has already started work in the Zinzilban Gorge and will complete the
field work during an additional week after the meeting. CM
Kim:
Studies of the Zinzilban nowakiids continue and the Now. (Dmitriella)
praesulcata Group of the Barrandian needs to be re-investigated, too. J.
Fryda:
Investigations of Emsian isotope stratigraphy has started in Czechia and
will be expanded to the Kitab sections. P. Lukes
is currently finishing an extensive revision of Barrandian nowakiids,
including Now. cancellata, which is important for the Emsian
substage subdivision. The Bulletin of Geosciences is available for fast
publication of new Zinzilban results and correlation summaries. CM
Feist:
New Zinzilban data need to be published quickly. TM
Izokh:
The entry of Po. nothoperbonus seems to be a good level for the
intra-Emsian substage boundary but both nothoperbonus and Po.
inversus should be restudied carefully. Chairman:
SDS has decided to search for a level close to the Dalejan Event (e.g. Now.
cancellata level) for the substage boundary. Po. nothoperbonus
enters much earlier, in the middle of the Zlichovian and in the middle
of Anetoceras faunas. The
present members voted formally on the following conclusions: 1.
A
majority recommended to revise the base of the Emsian. A future GSSP
level shall be searched for near the entry of Po. excavatus (its
subspecies or morphotypes) in order to correlate more closely with the
base of the brachiopod-defined classical Emsian of the German
type-region and with the Zlichovian of the Barrandian. 2.
In
accord with the decision at the Novosibirsk Business Meeting in 2005, any
future new Emsian GSSP will be placed in the Zinzilban section, too. 3.
The
current Emsian GSSP
in the Zinzilban Gorge shall become the GSSP for the base of a formal
Upper Pragian substage, possibly named as Zinzilbanian. 4.
Formal
voting on these issue will await the outcome of the new re-sampling by
various working groups. 5.
Results
of the re-sampling shall be reported immediately to the Uzbek (CM Kim)
and Novosibirsk SDS members and to the SDS Newsletter, preferably no
later than in 2010. 6.
All
results shall be published in a joint international publication,
coordinated by the Uzbek-Novosibirsk Devonian team. This requires
taxonomic agreements between involved specialists. 7.
Brachiopod
and other specialists are asked to correlate their zonations better with
the conodont and dacryoconarid successions, or to publish updated
summaries of such correlations. 8.
The
Emsian substage definition has to await new dacryoconarid and conodont
data and the outcome of the basal Emsian revision. 5.6.
D/C Boundary Based
on her excellent work on the new Uzbekistan sdection, M. Erina
has been proposed as additional member of the new D/C Boundary Working
Group. CM Feist
commented on the problems of the La Serre GSSP and on the problems to
find any other good section in future that is not equally affected by
the Hangenberg Event. Two
new CMs were proposed and voted on unanimously: Utkir
J. Rakhmonov,
Kitab State Geological Reserve, specialist of Devonian crinoids (especially
of columnals), rahmonov06@mail.ru. Jiri
Fryda,
Czech Geological Survey, specialist of gastropods and multiple
stratigraphic disciplines. The
Chairman
welcomed both in SDS and emphasized the importance that Uzbekistan is
represented by an additional active worker. Contributions
to Newsletter 24 are due at the end of 2008. The
Devonian Meeting 2009 in conjunction with the North American
Paleontological Convention (NPAC), in June in Cincinnati, will have a
focus on the relation between sea-level changes and evolution. The main
goal is to improve and revise the Devonian eustatic curve, a topic that
is of highest significance for the hydrocarbon exploration industry. It
is hoped to arrange in future some industrial sponsorship but this
requires improved industry contacts. The
Secretary
has repeated his offer to lead a field trip to the Old Red Devonian, in
conjunction with the 2002 IPC in London. The
Novosibirsk Group, notably CM Bakharev,
kindly offered a field meeting in 2011, visiting the Kuznetsk and
Kusbass regions of southern Siberia. The area offers fine Middle and
Upper Devonian successions and the D/C boundary. Since SDS has not yet
been to those regions, and in memory of the wonderful 2005 meeting, the
proposal was well received and accepted. The
2012 Business Meeting will have to be held in conjunction with the
Brisbane IGC. CM
Kim
and CM Rakhmonov
held brief closing speeches, inviting all SDS Members and Devonian
specialists to come back to the Kitab Reserve. The Chairman,
once more, thanked everybody involved with the meeting organisation.
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