Oman Pangea Symposium and Fieldmeeting by xcu79604


									126   Conference Report
                                                                                                   Huqf Area (S. Central Oman) and the
                                                                                                   Jebel Akhdar (Oman Mountains)". It was
Oman Pangea Symposium and                                                                          led by L. Angiolini, A. Nicora, J.-P. Platel
                                                                                                   and J. Roger, attended by 14 participants.
Fieldmeeting                                                                                       This excursion provided the opportunity to
                                                                                                   see and sample the Peri-Gondwanan Permian
                                                                                                   succession of the Sultanate of Oman. Against
Muscat, Sultanate of Oman, 7–20 January, 2001                                                      the spectacular background of mountains and
                                                                                                   desert, different faunal and floral associations
                                                                                                   and depositional environments from platform
The Pangea Project is a research program         shallow platform to basin and seamounts".         to shallow basin were shown.
sponsored by the IUGS Commission on              It was led by A. Baud, F. Bechennec, L.                 Starting in the desert of the interior
Global Sedimentary Geology (GSGP),               Krystyn, J. Marcoux R. Maury and S.               Oman, the excursion visited the Huqf area, a
which was officially launched in a Workshop      Richoz. Sixteen participants attended this        region marked by gently deformed and
held in May 1992 in Lawrence, Kansas,            field trip with great interest and took part in    uplifted Palaeozoic formations. Here, the
USA. It was then decided that Project Pangea     the lively discussions on the outcrops.           Early to Middle Permian is represented by
would focus on the most recent time of           Firstly, the geology of the belt located in the   two mega-sequences separated by a regional
super-continent accretion and dispersal, i.e.,   eastern part of the Arabian Peninsula, the        unconformity, recording two major transgres-
from the Carboniferous to the Jurassic, when     Oman Mountains was introduced. Briefly             sive events respectively controlled by the last
continents merged toward a geoid low, and        following a lower Permian rifting phase and       phase of the Gondwanan deglaciation and by
much of Pangea's climate appeared to be dis-     middle Permian break-up (birth of the             the opening of the Neotethys. The first
posed in an icehouse mode. Numerous              Neotethys), a wide carbonate platform devel-      sequence consists of Lower Permian glacio-
international activities (workshops, sym-        oped during late Permian and Triassic times       lacustrine deposits of the Al Khlata Forma-
posia, and conventions) have been organised      on the inner part of the margin. Carbonates       tion succeeded by the transgressive marine
under the umbrella of the Pangea projects        derived from the platform represented the         deposits of the Saiwan Formation, marking
over the years, and have resulted in the pub-    major source for the thick sequence of slope      the complete deglaciation of the region. The
lication of conference proceedings (5 until      carbonates deposited near the platform mar-       latter unit, of late Sakmarian age, yields a rich
now). The preparation of the International       gin. In the more distal areas, basinal and        and well-preserved brachiopod studied by L.
Conference on the Geology of Oman organ-         oceanic sedimentation resulted in various         Angiolini, in addition to bivalve, gastropod,
ised by the Oman Ministry of Commerce and        types of carbonate, chert and siliciclastic       crinoid and bryozoan fauna.
Industry, in cooperation with Sultan Qaboos      deposits, presently found in the Hawasina               Resting unconformably, the upper
University and the Mineralogical Institute of    Nappe. Middle Permian radiolarites and red        sequence is composed at the base of a thick
Bern University, was a unique opportunity        ammonoid limestones as Middle Triassic            fluvial terrigenous unit, the Gharif Forma-
for a Pangea Symposium proposal in this          black marls and limestones deposited on           tion. This sequence terminates with the
part of the world. This was done in 1999 by      lavas (seamounts) are cropping out on both        highly fossiliferous transgressive marls and
A. Baud and J. Marcoux, and was accepted         sides of the "autochthonous" tectonic win-        bioclastic limestones of the Khuff Formation
the same year by the Organising Committee.       dow as blocks of various dimensions, the          containing brachiopods, conodonts, ostra-
      With the presentation of new and recent    Oman Exotics. New results on Permian and          codes (studied respectively by L. Angiolini,
results on Permian and Triassic sediments of     Triassic magmatism were also presented.           A. Nicora & S. Crasquin), in addition to
Oman, the aim of the Symposium and the Field-          Spectacular and recently studied out-       bivalves, gastropods, cephalopods and trilo-
meetings was to provide a forum to geolo-        crops in Djebel Akhdar, Rustaq, Wadi Wasit,       bites. Only the Wordian part is exposed
gists who are interested in the Pangean time     Ba'id, Musjah, Aq Quil, Jebel Kawr and Mis-       below the angular unconformity of the Trias-
interval for discussing global changes related   fah areas allowed to reconstruct the former       sic continental Minjur Formation in the stud-
to Pangea integration and North Gondwana         geometry of the margin during Late Permian        ied outcrops.
and Central Tethys evolution. Members of         and Triassic times.                                     The Huqf succession represents a key-
the International Subcommissions on Per-               The theme of the Pre-Conference             section for the intercalibration of Early to Mid-
mian and on Triassic Stratigraphy were also      Excursion No. A02, from January 7–11,             dle Permian marine and continental biostrati-
invited. For petrographers and geochemists,      2001 was "Lower to Middle Permian Sedi-           graphical scales. In fact, if on one hand the
Oman is a key area for the study of the mag-     mentation on the Arabian Platform in the          fauna shows a marked transitional character,
matism linked with the Permian Neotethys
opening and with the Triassic intra-oceanic
seamounts. Sedimentologists, stratigraphers
and paleontologists working within the Per-
mian and Triassic time interval and inter-
ested by topics as diverse as biotic crisis,
extinction, recovery and evolution across the
Palaeozoic-Mesozoic transition used the
opportunity to discuss, observe and sample
the spectacular Permian and Triassic out-
crops of Oman's former continental margin,
from shallow shelf to deep marine sediments
and seamounts, and to participate in the
Pangea Symposium.
Pre-Conference Excursions
     Two field excursions were organised
before the Conference.
     The theme of the Pre-Conference
Excursion No. A01, from January 8–11,
2001, was "Permo-Triassic deposits, from         Figure 1 Participants and co-leaders of Pangea Excursion B0I with the Sumeini Range
                                                 (Permian to Cretaceous slope deposits) in the foreground.

                                                                                                                                       June 2001

being represented by cosmopolitan, Gondwa-         Richoz, S. (The Permian-Triassic boundary        tectonic window. The Permian and Triassic
nan, Tethyan and endemic taxa, on the other the    in Oman, a review) and of a poster by            shallow water carbonate rocks occurring in
newly named Gharif Paleoflora (J. Broutin) is       Krystyn, L., Richoz, S. and Baud, A. (A          this area belong to the Saiq and Mahil For-
erected as a standard for the Arabian Peninsula.   unique Permian-Triassic boundary section         mations. This was the subject of the first day
This warm humid assemblage is of outstanding       from Oman). This is the first discovery of a      trip. The Saiq Formation, about 400 m thick,
palaeogeographic significance, because it com-      completely dated Griesbachian coquinite          consists of transgressive-regressive cycles of
prises associated Gondwanan, Cathaysian and        limestone succession in Oman. This facies is     shallow carbonate and lava flows uncon-
Laurasian floral elements.                          unknown in other parts of the Tethys.            formably overlying Precambrian to Ordovi-
     Moving to the Oman Mountains, this                                                             cian strata and documenting the upper Per-
excursion examined, together with Excur-           Pangea paleoclimates, stratigraphy, magnetic     mian marine transgression and rift opening.
sion A01, the Permian succession cropping          insight and palynofacies                         The following Triassic dolomitic Mahil For-
out in the northwestern part of the Jebel                                                           mation confirms the cyclic and restricted
Akhdar window, along the Wadi Sahtan.              The first presentation was given by MacDon-       shallow marine environment upward.
Here, the Permian is represented by the Wor-       ald, W. and Ellwood, B. on Magnetic                    During the second day, the participants
dian marine Saiq Formation, lying with a           Insights into Permo-Triassic Pangea.             examined the basinal and oceanic sedimenta-
spectacular angular unconformity on the Pro-             Late Permian cooling followed by a         tion with the middle Permian red ammonoids
terozoic-Lower Paleozoic autochthon series.        global warming was the subject of                limestones of Rustaq. The radiolarites of
The Saiq Formation consists of conglomer-          Beauchamp, B. and Baud, A. in "Demise of         Buday'ah also deposited on lavas, cropping
ates at the base overlain by bioclastic lime-      Permian biogenic chert along the margins of      out as slices of various dimensions.
stones and reef limestones, which are capped       NW Pangea, Western Tethys and Gondwana:                Carbonates derived from the platform
by dolomites. This unit marks the transgres-       evidence for paleoceanographic disruption        represented the major source for the thick
sion on the newly formed Neotethyan margin.        and global warming", and a late Permian          sequence of slope carbonates (the Sumeini
                                                   warming was presented by Wopfner, H. (Late       Group) deposited near the platform margin,
Pangea Symposium                                   Palaeozoic to Early Triassic climatic transi-    cropping out in the Sumeini area near the
                                                   tion between Africa and the Southern Alps).      border between Oman and the United Arab
     Between January 12–16, 2001, the con-
                                                         Stratigraphy of Permian or Triassic sed-   Emirates. The lower part of this group (about
ference on the geology of Oman attracted
                                                   iments was presented by Jin Yugan (Lopin-        1700 m thick) is included in the Maqam For-
about 400 scientists from all over the world.
                                                   gian), Bachmann, G.H., Brueckner-Roehling,       mation, late Permian to late Triassic in age.
As part of the conference, the 2-day Pangea
                                                   S., Exner, M., Kedzierski, J. and Szurlies, M.   Key section of the Oman margin architec-
Symposium started on January 14, in which
                                                   (Sequence stratigraphy of the Scythian-          ture, the Wadi Maqam was re-investigated in
18 oral communications and 5 posters were
                                                   Anisian transgression, Triassic type region,     terms of biochronology, sequence and iso-
presented. In their introduction, A. Baud and
                                                   Germany), Mandl, G.W. (From Triassic sea         tope stratigraphy: this was the subject of the
B. Beauchamp stated the general purposes of
                                                   to Cretaceous orogen—The Austroalpine sec-       third and the fourth days of the excursion.
the Pangea Project and emphasised interna-
                                                   tor of the Tethyan shelf, Eastern Alps, Aus-           Thanks to the Organising Committee in
tional cooperation. The main items of scien-
                                                   tria), Kozur, H.W. (Ladinian and Carnian         Muscat, to the Sultan Qaboos University, to
tific progresses are summarised as follows.
                                                   palaeogeography of southern Turkey and its       the Oman Ministry of Commerce and Indus-
Stratigraphy and depositional models of the        importance for the development of the Trias-     try, and particulary to Dr. Hilal bin
Permian and Triassic sediments in Oman             sic Tethyan faunal provinces).                   Mohammed Al-Azri, Director General of
                                                         Sedimentology, correlations, paleoecol-    Minerals and to Prof. Peters and his collabo-
A series of presentations on new results on        ogy and palynology of the Permian-Triassic       rators in Bern. All of them made great efforts
the Permian and Triassic stratigraphy and          boundary interval were the subject of 4 pre-     for the complete success of the conference
correlations were given by Angiolini, L.,          sentations: —Brookfield, M. (Sedimentology        and the excursions.
Balini, M., Garzanti, E., Nicora, A. and Tin-      of the Permo-Triassic boundary sections in
tori, A. (The Gondwanan deglaciation in            Kashmir, India),—Twitchett, R.J. (High res-
central Oman: paleontological and sedimen-         olution, global correlation of the Permian-      Aymon Baud
tological evidence), Broutin, J., Berthelin,       Triassic interval),—Twitchett, R.J. and          Chairman of the IUGS Commission on
M. and Crasquin-Soleau, S. (The Permian            Looy, C.V. (Rapid and synchronous collapse       Global Sedimentary Geology (GSGP)
                                                   of end-Permian marine and terrestrial            Co-leader of the Oman Pangea Symposium and
'Gharif paleoflora' and the ostracodes from
the Khuff Formation, Huqf area, Sultanate of       ecosystems),—Spina, A., Cirilli, S and Baud,
                                                                                                    Director of the Geological Museum,
Oman), Archbold, N.W. (Oman to western             A. (Palynology of the uppermost Permian-         BFSH2-UNIL
Australia: Correlation of the Peripheral           basal Triassic successions in the High Arc-      CH-1015 Lausanne
Gondwanan Permian), Bernecker, M. (Sec-            tic, Canada and comparison with some PTB         SWITZERLAND
ond-order cycle development of the Arabian         Gondwanian localities).                          E-mail:
platform and Hawasina seamounts: Permian                 All the abstracts of the Pangea Sympo-
and Triassic outcrop data from central             sium are available on the Web at                 Jean Marcoux
Oman), Cordey, F., Baud, A., Béchennec, F.,                 Co-leader of the Oman Pangea Symposium and
Gorican, S. Krystyn, L. and Robin C. (Per-                                                          Fieldmeeting
mian-Triassic deep water sediments of the          Post-Conference Excursion                        Professor at Paris VII University
Wadi Wasit revisited).                                  The Symposium was followed on January       Sciences physiques de la terre
      Recent isotope studies were presented by     17 by a 4-day Post-Conference Excursion (B01)    Pl. Jussieu 2
Richoz, S., Atudorei, V., Baud, A. and Mar-        on "Permo-Triassic deposits from shallow         F-75251 Paris Cedex 05
coux, J. (Upper Permian to lower Triassic          water to base of slope and basin", led by A.     FRANCE
carbon isotope record: review and new data                                                          E-mail:
                                                   Baud, F. Bechennec, F. Cordey, J. Marcoux, R.
in the Oman Mountains, from the shallow            Maury, J. le Metour and S. Richoz.               Benoit Beauchamp
platform to the basin) and Richoz, S., Baud,            The Oman Mountains display a seg-           Past Chairman of GSGP
A., Marcoux, J. and Cordey, F. (Lower Trias-       ment of the Gondwanian margin, interpreted       Geological Survey of Canada
sic carbon isotope stratigraphy of the Sumeini     as a flexural upper plate. The Permian-Trias-     3303, 33rd Street NW
slope deposits, Maqam C, NW Oman).                 sic sequence deposited on the inner part of      Calgary, Alberta T2L 2A7
      New data on Permian-Triassic bound-          this margin is exceptionally well exposed in     CANADA
ary were the subject of a talk by Baud, A.,        the Saih Hatat Mountains, as part of the         E-mail:
Cordey, F., Krystyn, L.Marcoux, J. and             "autochthonous" which crops out in a large

Episodes, Vol. 24, no. 2

To top