People at Fort Hoofddijk

Marilyn Monster
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M.W.L. Monster, MSc
Paleomagnetic Laboratory
Fort Hoofddijk
Department of Earth Sciences 
Utrecht University 
Budapestlaan 17, 3584 CD Utrecht 
The Netherlands 

Phone +31 30 253 1361


Personal webpage

Research of Marilyn Monster

High-resolution records of geomagnetic field behaviour: the next generation of joined 40Ar/39Ar dating and paleointensity determination for the last 150 kyr
The Earth's magnetic field is generated in the liquid outer core of the planet. At the Earth's surface, the magnetic field is essentially a dipole field, but regionally variations in direction and intensity that cannot be described by a dipole can occur. Analyses of geomagnetic field variations have resulted in a series of geomagnetic field models such as CALS10k (Korte and Constable, 2011) for the past 10 kyr. The intensity information feeding into these models, however, is much less well-constrained than the directional data. Furthermore, for ages > 10 kyr, the database is considerably more fragmentary and is dominated by records from Hawaii.
The first component of this research project is to obtain reliably absolute palaeointensities (PIs) from lavas from two regions: the Mediterranean (Sicily, Nisyros) and the Canary Islands (El Hierro). PI determination is a notoriously difficult and laborious process with a rather low success rate. Many specimens fail selection criteria and the ones that pass may yield erroneous PI estimates. To increase the success rate a multi-method approach is used. Comparing results from three different PI determination methods (the classic Thellier-Thellier method (Thellier and Thellier, 1959), the microwave method (e.g. Hill and Shaw, 1999) and the multispecimen protocol (Dekkers and Boehnel, 2006; Fabian and Leonhardt, 2010)) provides an extra check on the reliability of the obtained PIs. When two or all three methods yield the same PI, the obtained PI is close to the correct value. (Marilyn's MSc project; results to be published in 2014.)  

Drilling in lava flows on El Hierro
The second component of this project consists of (re)dating sites that yield good PI results using the new Thermo Fisher HELIX MC multi-collector mass spectrometer. It was installed at VU University Amsterdam in 2013 and will start measuring samples in the first months of February. Its peak valley resolution and peak resolving power are very high, allowing to fully resolve isobaric interferences of hydrocarbon fragments and partially resolve hydrochloric interferences. Measuring a resolved Ar-36 beam should result in a dramatically more accurate determination of the argon isotope ratios and thus more precise Ar/Ar ages. 

El Hierro - view over El Golfo valley

Marilyn's project is supervised by Mark Dekkers and Klaudia Kuiper

publicationsPublications of Marilyn Monster
  • Monster, M.W., de Groot, L.V. and Dekkers, M.J. (2015). MSP-Tool: a VBA-based software tool for the analysis of multispecimen paleointensity data. Front. Earth Sci. 3:86. doi: 10.3389/feart.2015.00086   
  • Monster, M.W.L., de Groot, L.V., Biggin, A.J. and Dekkers, M.J. (2015). The performance of various palaeointensity techniques as a function of rock-magnetic behaviour  - a case study for La Palma, Physics of the Earth and Planetary Interiors, 242, 36-49.
  • Monster, M.W.L. (2014). Aadmagnetisch veld van de afgelopen 500.000 jaar gereconstrueerd, Geo.brief, 39(4), 10 - 11.  
  • S. Semraua, M.W.L. Monster, M. van der Knaap, B.I. Florea, T. Schmidt and M. Overhand (2010). Membrane lysis by gramicidin S visualized in red blood cells and giant vesicles, Biochim. Biophys. Acta, 1798, 2033-2039.