Arid Belt and Adjacent Oceans (10° - 30°)

Co-Leaders; Gerhard Bachmann and Paul E. Olsen
Panel: David E. Brown, Maurizio Gaetani, Simon Gould, Andrew B. Heckert, Luba Jansa, Jacques Laskar, Giovanni Muttoni, Mohammed Et-Touhami, Abdelilah Tourani, Michael Szurlies
 

The latitudinal belt from about 10° N to 30° N paleolatitude constitutes a critical area of Pangea, largely because it is this area in which the classic Germanic basin developed, and it is also an region chracterised by a strong development of marine, paralic, and especially evaporite basins in and adjacent to the Tethys Ocean. As a consequence, not only is this region critical for integrating the marine and terrestrial time scales, but it also constitutes one of the most important areas of salt deposits in the world, with major implications for climate, oceanic geochemistry, and hydrocarbon reserves.
 

MAIN PROBLEMS

The panel focused on four major problems that were best addressed by coring in the 10° - 30° latitudinal transect:

1) Arid Belt and Adjacent Oceans Climatic Record: Outcrops of sections continental rocks deposited in this belt visually show a strong lithological cyclicity, including the classic studies in marine Middle Triassic sequences in the Alps (e. g. Goldhammer et al., 1987, 1990; Hinnov and Goldhammer, 1991; Hinnov, 2000) and Early Triassic to Early Jurassic marine sequences in the Germanic basin, France, and England (e. g. Aigner, 1985; Röhl, 1988; Kramm, 1997) as well as the more continental sequences of Middle Triassic to Early Jurassic age (e. g., Olsen, 1997; Olsen et al., 1989; Olsen and Kent, 2000; Szurlies et al., 1998; Pöppelreiter. 1998; Aigner and Bachmann, 1989; Nitsch, 1995; Hambach et al, 1998; Beutler et al., 1998; Hofmann et al., 1998). However, other than studies of the Middle Triassic Latamar and the Jurassic sequences, very little is known quantitatively about this cyclicity, and even less is known about how it the cyclicity evolves through time in one place or how the marine and continental cyclicity is related, or how the cyclicity is related to events in other latitudinal areas. Much of these problems stems from a lack of high resolution temporal correlation between the various sections and a lack of long continuous outcrops, both addressable through coring.

Especially interesting is the potential to understand the relationship between high-frequency marine cyclicity and the contemporaneous continental cyclicity reflected in lacustrine or evaporite settings, within the same climatic zone. The origin of high frequency marine cyclicity, apparently attributable to astronomical forcing during "Hot House" times is major problem (e. g. Jacobs and Sahagian, 1993; Kendall, 1995), addreessible in some of these areas, notably Europe and Morocco.

2) Integrated Time Scale: The Newark Basin Coring Project time scale established a high-resolution orbitally tined time scale for the Late Triassic. However, because of the uncertainty in temporal correlation between the totally continental Newark basin and marine sections a time scale that fully integrates the orbital tuning with marine and global biostratigraphy is still a long way off. Clearly what is needed are studies of continuous marine sections with with biostratigraphic control, and recoverable high-resolution paleomagnetic polarity stratigraphy. At the present nearly all published paleomagnetic studies in Triassic marine sections are from highly condensed sections. attractive paleontologically, but problematic because of the presence of observed and inferred hiatuses (e. g. Gallet et al., 2000). Suitable long, continuous sections do exist, and while outcrop studies are underway, it is clear to get sections comparable to the Newark basin, in sampling and stratigraphic completeness coring will be necessary.

One of the largest areas for which we know very little is the geochemistry of Triassic-Early Jurassic oceans. The abundance of low-thermal-maturity marine section in the European Tethys allows for the possibility of developing marine chemostratigraphies that are fully integrated with the orbitally tuned time scale. Sections elsewhere in the work with suitable deposits could them be cored with the marine reference sections in this climate zone with the promise of working out marine oceanographic and climate proxies, and their geographic gradients.

3) Stratigraphic-Tectonic Development of the Conjugate Margins: The conjugate margins of the arid belt provide one of the most exciting and critical comparisons across the Pangean breakup front. This is especially true in the southern part portion of this longitudinal transect including Nova Scotia and Morocco and the Grand Banks and Iberia. This region was avery climatically sensitive area with abundant salt basins. The magnetostratigraphy is known to be recoverable both in outcrop and core  (e. g. Kent and Olsen, 2000), there are abundant macro- and micro-biostratigraphically useful taxa (e. g. Dutuit, 1976; Olsen et al., 1989; Olsen, 1997; Fowell and Traverse, 1995; Tourani et al., 2000; Courel et al., 2000), and there is obvious cyclicity in most units including the salts (e. g., Smoot, 1991; Olsen, 1997; Hoffman et al., 1999; Et Touhami, 2000).

Sequence Strat and Boundaries - good hints
Conjugate transects aims toward the Tethys - source of moisture
Enormous amount of seismic
Tectonic aspects

Moving out of the volcanic margin - boundary
Transition between rifting-drifting CAMP and tectonic inversion
Symmetry-Asymmetry?
Transition with European
 

 
 
 
 
 

4) Triassic-Jurassic Boundary in Mid Latitudes
 

CORING AREAS ADDRESSING PROBLEMS

Criteria
a) sensitive climate zone
b) high accumulation rate
c) continuous sections
d) cont-mixed-marine
e) things to measure
Specific Target Areas
1) Germanic basin
Outcrops - massive classic info, but on thin edges
Magnetostratigraphy 100%
Biostratigraphy 100% pollen
ostracodes
marine in Muschelkalk - ammonites, conodonts, vertebrates
Isotope/geochemistry Stratigraphy - ?? marine-continental (if there is a standard
Cyclostratigraphy - variations on themes
Sequence Stratigraphy - boundaries, cycles  basin deeps should have correlative conformities Lots of seismic
2) Mid-latitude conjugate margin transect (nearly non-volcanic): Salt basins (morocco - Fundy
In the sensitive part of the arid belt
Basin non marine to marine (salt basins)
Magnetostratigraphy - works tested in outcrop and core
Biostratigraphy - vertebrates - pollen - ostracodes
Isotope stratigraphy/geochemistry - ???? test underway
Cyclostratigraphy - very good even in the salt
Sequence Strat and Boundaries - good hints
Conjugate transects aims toward the Tethys - source of moisture
Enormous amount of seismic
Tectonic aspects
Moving out of the volcanic margin - boundary
Transition between rifting-drifting CAMP and tectonic inversion
Symmetry-Asymmetry?
Transition with European
3) SICILY MONTE TRIONA - CORE OUTCROP PIZZO MONDELLO - OUTCROP Pelagic - nice contrast to sequence strat
Magstrat 100%
Isotopic Stratigraphy 100%
Biostratigraphy (Tethyan) Conodonts 100%
Ammonites 10%
Halobids 100%
Pollen (at least Carnian)
Nannofossils (!)Test conodont extinction at end Triassic extinction??
Cyclostratigraphy (big cycles obvious) Possible Triassic-Jurassic boundary at Monte Cammarata Lot of seismic
4) Greenland (Fleming Fjord) STRATEGIC AREAS

´ Jurassic - French pre-Alps Dauphinais thick ~paleomag (dark)
´ China - Yantze marine Triassic- to Jurassic
´ Iran - Shem Shak Continental TR-J to Pliensbachian marine 25° N, 500-1000 m
´ Karoo, Argentina, Wombat, Chile, Madagascar

Overlaps Large overlap with the Biotic

Conceptual overlap with Western Equatorial Pangea

Nova Scotia Morocco Conjugate Margin transect and Basin Evolution Group

Greenland Overlaps with Biotic, and High Latitudes

Conceptual Overlap with CAMP/LIP

References

Aigner, T., 1985, Storm depositional systems. Lecture Notes in Earth Science v. 3, p. 1-174.

Aigner, T. and Bachmann, G, H., 1989, Dynamic stratigraphy of an evaporite-to-red bed sequence, Gipskeuper (Triassic), southwest German Basin. Sedimentary Geology v. 62, p. 5-25.

Beutler, G. Ernst, W., Kellner, A., and Schubert, J., 1998, Stratigraphy, sedimentary environments and cyclic deposition of the Keuper in the Southeastern part of the Germanic basin. Hallesches Jahrbuch für Geowissenschaften, Reihe B, Beiheft 6,  p. 141-152.

Courel, L., Salem, A., Ismail, B., El Mostaine. M., Fekirine, B., Kamun, F., Mami, L., Oujidi, M., and Soussi, M., 2000, An Overview of the epicontinental Triassic series of the Maghreb (NW) Africa). Zentralblatt fur Geologie und Palaontologie, Teil I, vol. 1998, p. 1145-1166.

Dutuit, J. M., 1976,  Introduction à lÝetude paléontologique du Trias continental marocain. Description des premiers stégocéphales recuellis dans le couloir dÝArgana. Mémoire du Muséum National dÝHistoire Naturelle C  36: 1-253.

Et Touhami, M., 2000, Lithostratigraphy and depositional environments of Lower Mesozoic evaporites and associated red beds, Kemisset Basin, northwestern Morocco. Zentralblatt fur Geologie und Palaontologie, Teil I, vol. 1998, p. 1217-1241.

Gallet, Y., Besse, J., Krystyn, L., Marcoux, J., Guex, J., and Theveniaut, H., 2000, Magnetostratigraphy of the Kavaalani section (southwestern Turkey): Consequence for the origin of the Antalya Calcareous Nappes (Turkey) and for the Norian (Late Triassic) magnetic polarity timescale: Geophysical Research Letters, v. 27, p. 2033.

Goldhammer, R. K., Dunn, P. A., Hardie, L. A., 1987, High frequency glacio-eustatic oscillations with Milankovitch characteristics recorded in northern Italy. American Journal of Science v. 287, p. 853-892.

Goldhammer, R. K., Dunn, P. A., Hardie, L. A., 1990, Depositional cycles, composite sea-level changes, cyclic stacking patterns, and the hierarchy of stratigraphic forcing: examples from the Alpine Triassic. Geol. Soc. Amer. Bull., v. 102, p. 535-562.

Hambach, U., Schslkowski, M., Fehmer, S., Reinhardt, L., and Ricken, W., 1998, High resolution rock magnetic investigraphions of the German Keuper - implications for sedimentary cyclicity and stratigraphy. Hallesches Jahrbuch für Geowissenschaften, Reihe B, Beiheft 5,  p. 64-65.

Hinnov, L.A., 2000, New perspectives on orbitally forced stratigraphy, Ann. Rev. Earth Planet. Sci. v. 28, p. 419-475.

Hinnov, L. A., and Park, J. J., 1999, Strategies for assessing EarlyˇMiddle (PliensbachianˇAalenian) Jurassic cyclochronologies. Phil. Trans. Roy. Soc. Lond. (Ser. A), v. 357, p. 1831-1859.

Hinnov, L.A., and Goldhammer, R.K., 1991, Spectral analysis of the Middle Triassic Latemar Limestone. Jour. Sed. Pet., v. 61, p. 1173-1193.

Hofmann, A., Tourani, A., and Gaupp, R., 1998, Cyclostratigraphy evolution of Triassic to lower Jurassic continetal red beds in a rift-basin setting (Argana Valley, Western Morocco). Hallesches Jahrbuch für Geowissenschaften, Reihe B, Beiheft 5,  p. 74-75.

Jacobs, D. K. and Sahagian, D. L., 1993, Climate-induced fluctuations in sea level during non-glacial times, Nature v. 361, p. 710-712.

Kent, D. V. and Olsen, P. E., 2000, Magnetic polarity stratigraphy and paleolatitude of the Triassic--Jurassic Blomidon Formation in the Fundy basin (Canada): implications for early Mesozoic tropical climate gradients. Earth And Planetary Science Letters, v. 179, no. 2. p. 311-324.

Kendall, C. G. St. C., Ehrlich, R., and Levine, P. A., 1995, The Enigma of Third Order Sea Level Cycles: a Cosmic
Connection? In B. U. Haq, ed., Sequence Stratigraphy and Depositional Response to Eustatic, Tectonic and Climatic forcing; Kluwer Academic Publishers, p.367-376.

Kramm, E., 1997, Stratigraphie des Unteren Muschekalks in Germanischen Benken. Geol. Palaeont., v. 31, p. 215-234.

Nitsch, E., 1995, Facies, Diagenese und Stratigraphie der Grabfeld-Gruppe Süddeuchlands (Keuper Trias). Ph.D., Thesis, University of Köln.

Olsen, P. E. 1997. Stratigraphic record of the early Mesozoic breakup of Pangea in the Laurasia-Gondwana rift system. Ann. Rev. Earth Planet. Sci. v. 25, p. 337-401.

Olsen, P. E. and D. V. Kent, 2000, High resolution early Mesozoic Pangean climatic transect in lacustrine environments. Zentralblatt fur Geologie und Palaontologie, Teil I, vol. 1998, p. 1475-1496.

Olsen, P. E., Schlische, R. W., and Gore, P. J. W. (and others), 1989, Field Guide to the Tectonics, stratigraphy, sedimentology, and paleontology of the Newark Supergroup, eastern North America. International Geological Congress, Guidebooks for Field Trips T351, 174 p.

Pöppelreiter, M., 1998, Controls on epeiric successions exemplified with the mixed silicastic - carbonate Lower Keuper (Ladinian, Germanic Basin), Ph.D., Thesis, University of Tübingen.

Röhl, U., 1988, MultistratigraphischesZyleengliederung in Oberen Muschelkalk Nord- Und Mittekdeutschelands. Ph.D., Thesis, University of Bonn.

Smoot, J. P.. 1991, Sedimentary facies and depositional environments of early Mesozoic Newark Supergroup basins, eastern North America. Palaeog. Palaeocl. Palaeoec. v. 84, p. 369-423.

Szurlies, M., Menning, M., and Nowaczyk, N. R., 1998, Magnetostratigraphy and cyclic stratigraphy pf the lower Buntsandstein (Northern foreland of the Harz Mts Central Gernmany). Hallesches Jahrbuch für Geowissenschaften, Reihe B, Beiheft 5,  p. 171-172.

Tourani, A., Lund, J. J., Benaous, N., and Gaupp, R., 2000, Stratigraphy of Triassic syn-rift depsoition in Western Morocco. Zentralblatt fur Geologie und Palaontologie, Teil I, vol. 1998, p. 1193-1215.

Weedon, G. P., Jenkyns, H. C., Coe, A. L., and Hesselbo, S. P.,  1999, Astronomical calibration of the Jurassic time-scale from cyclostratigraphy in British mudrock formations, Phil. Trans. Roy. Soc. Lond. (Ser. A), v. 357, p. 1787-1814.