Understanding patterns
and processes of past biotic crises is no longer a matter of pure academic
interest. There is growing scientific consensus that we have recently entered
a period of (man-induced) mass extinction, resulting in a 50 % loss of
the global biodiversity within the next 100 years. Such high rates of diversity
loss have occurred only five times since complex life emerged: the ‘Big
Five’.
CAMP
basalts in the Argana Basin in Morocco
Here, we focus on mass
extinction(s) during the Late Triassic (~230-200 Ma) that belong to the
‘Big Five’ and that mark the advent of the dinosaur Era. It is still the
most controversial biotic crisis, but yet it is the least studied, because
complete and well-dated sections are very limited, both in the marine and
terrestrial realm. Consequently, the lack of robust evidence makes it difficult
to evaluate whether the changes were catastrophic or gradual.
In marine
habitats, significantly increased extinction rates at the end of the Triassic
are well documented. By contrast, the continental picture is equivocal.
Catastrophic changes among vertebrates and plants have been suggested in
the eastern US, but contradictory data are reported from Europe where macrofossils
indicate a more gradual transition in vegetation.
Triassic
red beds in Morocco
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By making use of magnetostratigraphy,
astrochronology and
analysis of sedimentary organic matter, the present project aims at the
identification of the causal connection between Late Triassic events in
the terrestrial and marine biosphere. |
The
Moroccan Triassic red beds seem cyclic
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Palaeomagnetism
and cyclostratigraphy
The major advantage
of magneto- and cyclostratigraphic dating techniques is that both can be
applied to continental and marine sequences, allowing a direct intercalibration
of the two different environments. Extensive magnetostratigraphic studies
have earlier been performed on marine sequences of the European Late Triassic,
but cyclostratigraphic analyses have so far never been included.
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Meanwhile,
Martijn has done fieldwork in the Argana basin of Morocco, on late
Triassic red beds that precede the eruption of the CAMP basalts.
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We will thus initially
focus our cyclostratigraphic studies on those sections for which a magnetostratigraphy
is already established (e.g Pizzo Mondello on Sicily, Argana basin in Morocco),
but all new potential target sequences in Germany, Austria and Morocco
will directly be studied by an integrated magneto-cyclo stratigraphic approach.
Emphasis will also be put on environmental magnetic parameters (magnetomineralogy
and grain size), which are very sensitive to minute changes in the environment.
Phase relations with the astronomical cycles will directly be derived from
the results of the biogeological components. |
2011
-
Deenen, M.H.L.,
Langereis, C.G., Krijgsman, W., El Hachimi, H. And El Hassane, C. (2011).
Paleomagnetic research in the Argana basin, Morocco: Trans-Atlantic correlation
of CAMP volcanism and implications for the late Triassic geomagnetic polarity
time scale. Journal of African Earth Sciences (special issue), in
press.
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Deenen, M.H.L.,
Langereis,, C.G., van Hinsbergen, D.J.J. and Biggin, A.J. (2011). Geomagnetic
secular variation and the statistics of palaeomagnetic directions, Geophys.
J. Int., 186, 509-520
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Deenen, M.H.L.,
Krijgsman, W. and Ruhl, M. (2011). The quest for E23r at Partridge Island
(Bay of Fundy): CAMP emplacement post-dating the end-Triassic extinction
event in Canada, Canadian J. Earth Sci., accepted
-
Hüsing,
S.K., Deenen, M.H.L., Koopmans, J.G. and Krijgsman, W. (2011). Magnetostratigraphic
dating of the proposed Rhaetian GSSP at Steinbergkogel (Upper Triassic,
Austria): Implications for the Late Triassic time scale, Earth Planet.
Sci. Lett., 302, 201-216.
2010
-
Deenen, M.H.L.
(2010). A new chronology for the late Triassic to early Jurassic,
Geologica
Ultraiectina, 323
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Deenen, M.H.L.,
Ruhl, M., Bonis, N.R., Krijgsman, W., Kürschner, W.M., Reitsma, M.,
Van Bergen, M.J. (2010). A new chronology for the end-Triassic mass extinction,
Earth
and Planetary Science Letters, 291, 113-125......
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Ruhl, M.,
Deenen, M.H.L., Abels, H.A., Bonis, N.R., Krijgsman, W. and Kürschner,
W.M. (2010). Astronomical constraints on the duration of the early Jurassic
Hettangian stage and recovery rates following the end-Triassic mass extinction
(St. Audrie’s Bay/East Quantoxhead, UK) , Earth and Planetary Science
Letters, 295, 262-276.
2008
-
Biggin, A.J.,
Van Hinsbergen, D.J.J., Langereis, C.G., Straathof, G.B. and Deenen, M.H.L.
(2008). Geomagnetic secular variation in the Cretaceous Normal Superchron
and in the Jurassic, Phys. Earth Planet. Inter., 169, 3-19
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