Research at Fort Hoofddijk

A wonder of such nature I experienced as a child of 4 or 5 years, when my father showed me a compass.That this needle behaved in such a determined way did not at all fit into the nature of events which could find a place in the unconscious world of concepts. I can still remember - or at least believe I can remember - that this experience made a deep and lasting impression upon me. Something deeply hidden had to be behind things ... 
Albert Einstein 
  • One: Variatons of the geomagnetic field
  • Two: Neotectonic and geodynamical research
  • Three: Rock magnetism & environmental magnetism
Fort Hoofddijk
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Variations of the geomagnetic field

Age and timing of records of geomagnetic variations

Age and timing of records of geomagnetic variations
Secular variation before, during and after a Superchron and implications for the geodynamo with an emphasis on the Permo-Carboniferous Superchron as well as on the Archaean and Proterozoic. Excellent records of secular variation were recorded in Permian red beds, and the project of Marcela Haldan aims at significantly extending records of SV in these sediments, both during and after the Permian superchron. 
Researchers: Marcela Haldan, Cor Langereis, Mark Dekkers, Andy Biggin
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Archeomagnetic studies in Turkey
The archeomagnetic record of sites of known age in Turkey allows establishing a master curve for the region that can subsequently be used for dating purposes. Further it consists valuable input for global field models. In a later stage archeointensity information will be gathered as well to further refine our description of the Earth’s magnetic field in the recent past. 
Researchers: Pinar Ertepinar, Cor Langereis, Andy Biggin 

Absolute paleointensity methods
Retrieving the ancient intensity, the paleointensity, of the Earth’s magnetic field from lavas is constituting a major challenge. The project involves comparing several paleointensity determination techniques, including the ‘multispecimen method’ on synthetic samples and historical lavas. 
Researchers: Lennart de Groot, Mark Dekkers, Andy Biggin

Magnetostratigraphy and Astronomical Polarity Time Scales

The application of astronomical polarity time scales is crucial in tectonostratigraphic and paleogeographic analyses. Integrated magneto-bio-cyclostratigraphy of late Neogene land sections in the (circum) Mediterranean, and the construction of astronomical polarity time scales will be used for understanding the neotectonics and resulting sedimentary systems and their time-dependent basin geometry. 
Supervisors: Wout Krijgsman, Cor Langereis and Guillaume Dupont-Nivet

A project on the Late Miocene evolution of the Mediterranean - Atlantic - Indian Ocean Gateways establishes high-resolution time frames for the sedimentary sequences of the gateway basins with special emphasis on the timing of their restriction and closure. Paleogeographic reconstructions will aid in decyphering the closure mechanism. 
Researchers: Wout Krijgsman, Silja Hüsing

Miocene to Pliocene evolution of the western Paratethys (Transylvanian and Pannonian basins) and spatial-temporal connections between Miocene semi-isolated basins
A high-resolution chronologic framework is aimed at for the Neogene sediments deposited in the western Paratethys area focussing on the middle and upper Miocene of the Pannonian and Transylvanian basins. n tectono- stratigraphic studies to unravel This allows unraveling the tectono-stratigraphic evolution of the Pannonian-Carpathian orogenic system and a correlation of events between the Paratethys and Mediterranean realms.
Researchers: Arjan de Leeuw, Wout Krijgsman

Late Triassic extinction(s): a singular event or multiple ecological avalanches ?
Understanding past biotic crises has passed beyond pure academic interest: the current anthropogenic-induced loss of biodiversity rivals mass-extinctions in the geological past. The project aims at providing a high-resolution time frame for the Late Triassic in order to unravel cause and consequence of the Triassic-Jurassic mass extinction.
Researchers: Martijn Deenen, Wout Krijgsman

Paratethys magnetostratigraphy and time scales, and connections with the Mediterranan
The northward plate tectonic motion of the African/Arabian continent during the Neogene (24-0
Myrs ago) has led to the closure of the Tethys Ocean and created the Paratethys domain: a large endemic water mass that extended from Austria to Iran, with the Black Sea and Caspian Sea as actual remnants. The time scale for the Paratethys domain is highly equivocal and controversial ages exist for many events and geological stage boundaries, although suitable conditions exist to develop astronomical polarity time scales.
One of the many key questions concerns closure and opening of the marine connection(s) between Mediterranean and Paratethys, and is at present far from understood.
In this project, we aim to develop a high-resolution astronomical polarity time scale for the
Paratethys with special focus on the last ~10 Myr of geological history which requires a multi-disciplinary integrated approach and suitable sedimentary sequences. 

Several ongoing projects tackle this issue, like the Dutch-Russian collaboration on Taman Peninsula (Russia) and in Azerbaijan. High-resolution (micro)paleontological, palynological/paleoecological, geochemical (isotopes) and cyclostratigraphic records aim at detailed reconstructions of the environment and climate history of Eurasia. 
Researchers: Iuliana Vasiliev, Wout Krijgsman, Marius Stoica, Cor Langereis, Katya Grundan, Ksenia Pavlova. See also Andy Lotter and Wolfram Kürschner at the Paleoecology Group at the Department of Biology 


Neotectonic and geodynamical research
Archean drifting continents: plate tectonics during Early Earth ?
Paleomagnetic research on the Pilbara craton (Australia) and the Barberton craton (South Africa) is carried out to test different models on early Earth tectonism. It concerns a cooperation with the Utrecht Structural Geology and Tectonics group (prof. Stan White) and with prof. Maarten de Wit (University of Cape Town, South Africa). Ar/Ar dating forms an important part of the research and is done by Jan Wijbrans (Free University, Amsterdam). 
Researchers: Tanja Zegers & Cor Langereis 

Opening and closure of the Tethys oceans: Mesozoic Cimmerian deformation around the present-day Black Sea 
The geodynamic evolution of the areas surrounding the Black Sea - the North Dobrogea Orogen, Crimea, the Greater Caucasus and the Turkish Pontides, Anatolides and Taurides - is complex. Paleomagnetic information constrains the paleolatitude which in turn helps assessing the veracity of various proposed tectonic scenarios.
Researchers: Maud Meijers, Cor Langereis, Douwe van Hinsbergen, Randell Stephenson (VU)

Paleomagnetic constraints on the  kinematics of Anatolia
Southeastern Anatolia is the northernmost extension of the Arabian Plate. It forms a key area for the study of the collision history of the Arabian and Eurasian plates. are recorded continuously. Research involves a blend of paleomagnetsm, structural geological mapping, and interpreting GPS motions.
Researchers: Ahmet Peynircioglu, Cor Langereis, Douwe van Hinsbergen, Nuretdin Kaymakçi

Uplift rate of the Tibetan plateau and its relation to global climate change
Growth and uplift of the Tibetan plateau triggers the onset of Asian monsoons, and thus generates a major change in global climate. The best-exposed Tertiary basin of northern Tibet – the Xining basin – is targetted to decipher independently the tectonic and climatic components of the sedimentary record in response to Tibetan uplift. Magneto-cyclostratigraphic analysis and a wide array of paleoenvironmental proxies are being gathered in the basin deposits. In addition, the exhumation history of adjacent granitic massifs is being quantified using U-Th/He thermochronology.
Researchers: Guillaume Dupont-Nivet, Wout Krijgsman, Cor Langereis
 


Rock magnetism & environmental magnetism
Fundamental research into the magnetic properties of the various natural magnetic minerals. Current efforts (Mark Dekkers, Guillaume Dupont-Nivet) utilise very high pulse magnetic fields (high field pulse laboratory, Toulouse (France)) to constrain the anisotropy constants of hematite and goethite. 

Magnetostratigraphy and environmental magnetic change around the middle Miocene global climate change in the Mediterranean
The global climate changed in the middle Miocene, likely caused by ice sheet expansion on Antarctica. The response of the Mediterranean sedimentary basins in terms of environmental change is the aim of this project. The middle Miocene marls of Monte Corvi (Italy) have yielded a robust astronomical time scale. Secondly, suitable sections in the Mediterranean and a possible gateway to the Indian Ocean will be studied. 
Researchers: Silja Huesing, Wout Krijgsman, Mark Dekkers

Automation of paleomagnetic and rock-magnetic data acquisition
A DC-SQUID magnetometer is interfaced with a robot that allows completely automated data acquisition of up to 96 samples. Options includes alternating field demagnetization, ARM and IRM acquisition. 
Researchers: Tom Mullender, Mark Dekkers 

Remagnetization in southwestern Turkish basins
Recent developments enable to differentiate remagnetized strata on a rock-magnetic basis. The method proposed for a Spanish Pyrenean basin is further tested in several basins in soutwestern Turkey. 
Researchers: Douwe van Hinsbergen, Mark Dekkers

Paleo- and rock-magnetic methods in paleolitic archeology
Several homonine and Neanderthaler sites across Europe are being studied with an array of geophysical and geochemical methods with the aim to improve their age determination and to trace the evolution of the skills of our ancestors through time.
Researchers: Mark Sier, Wil Roebroeks, Mark Dekkers, Cor Langereis, Douwe van Hinsbergen 

NRM remagnetization and fluid flow
The recognition of pervasive remagnetization of the natural remanent magnetization (NRM) is essential for a correct interpretation of paleomagnetic data and, evidently, has important geodynamical implications. The research revolves around a key basin of Cretaceous age in the Pyrenees. The research strategy seeks to optimise a combination of mineral-magnetic, paleomagnetic and ‘non-magnetic’ methods. The latter methods include thin section and SEM/TEM microscopy on rocks and magnetic concentrates, determination of the 87Sr/86Sr ratio from carbonates, determination of smectite/illite ratios, and assessing scenarios for fluid movement through the rock pile by hydrological modeling.
Researchers: Zhihong Gong and Mark Dekkers

EUROPROX is a Deutsche Forschungs Gemeinschaft funded Bremen - Amsterdam - Utrecht - Université de Bordeaux - Southampton Oceanographic Centre - Massachusetts Institute of Technology graduate college for the training of PhD students. It aims to progress our understanding of the history of natural variability of biological and physical processes and their impact on climate and oceans. The Utrecht paleomagnetism group is involved with the advanced interpretation of magnetic proxy parameters.

And finally ...

Occasional projects are done in conjunction with archeological research (archeomagnetism) and with NITG (Geological Survey), e.g. on Pleistocene deposits in the Netherlands and Suriname.
Homepage of NWO NWO: Nederlandse organisatie voor Wetenschappelijk Onderzoek (Netherlands Organization for Scientific Research)
go to Homepage VMSG VMSG: Vening Meinesz  research School of Geodynamics 
ISES Homepage ISES: National Research Centre for Integrated Solid Earth Sciences