People at Fort Hoofddijk

Martijn Deenen
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Dr. M.H.L. Deenen
Paleomagnetic Laboratory
Fort Hoofddijk
Department of Earth Sciences, 
Utrecht University 
Budapestlaan 17
3584 CD Utrecht 
The Netherlands 

Phone +31 30 253 1676
Fax +31 30 243 1677


My PhD thesis

Natuurwetenschap & Techniek artikel (Dutch)

Research of Martijn Deenen

Late Triassic extinction(s): a singular event 
or multiple ecological avalanches ?
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

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. 

Interesting rock ...
The Moroccan Triassic red beds seem cyclic
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. 
Meanwhile, Martijn  has done fieldwork in the Argana basin of Morocco, on late Triassic red beds that precede the eruption of the CAMP basalts. 
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.

publications Publications of Martijn Deenen
  • Deenen, M.H.L., Langereis, C.G., Van Hinsbergen, D.J.J., Biggin, A.J. (2014). Erratum to Geomagnetic secular variation and the statistics of palaeomagnetic directions [Geophysical Journal International, 186, (2011) 509-520], Geophysical Journal International, 197 (1), 643.   
  • Hüsing, S.K., Beniest, A., van der Boon, A., Abels, H.A., Deenen, M.H.L., Ruhl, M., Krijgsman, W. (2014). Astronomically-calibrated magnetostratigraphy of the Lower Jurassic marine successions at St. Audrie's Bay and East Quantoxhead (Hettangian-Sinemurian; Somerset, UK), Palaeogeography, Palaeoclimatology, Palaeoecology, 403, 43-56.  
  • Deenen, M.H.L., Langereis, C.G., Krijgsman, W., El Hachimi, H. And El Hassane, C. (2011). Palaeomagnetic results from Upper Triassic red-beds and CAMP lavas of the Argana Basin, Morocco.  In: Van Hinsbergen, D.J.J., Buiter, S.J.H., Torsvik, T.H., Gaina, C. & Webb, S.J.(eds), The Formation and Evolution of Africa: A Synopsis of 3.8 Ga of Earth History. Geological Society, London, Special Publications, 357, 195–209.   
  • 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  
  • Deenen, M.H.L., Krijgsman, W. and Ruhl, M. (2011). The quest for E23r at Partridge Island (Bay of Fundy): CAMP emplacement postdates the end-Triassic extinction event at the North American craton, Canadian J. Earth Sci., 48, 1282-1291. 
  • 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. 
  • Deenen, M.H.L. (2010). A new chronology for the late Triassic to early Jurassic, Geologica Ultraiectina, 323  
  • 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....
  • 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. 
  • 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