Application of magnetic susceptibiliy in paleoenvironmental reconstruction
Quantitative magnetic susceptibility (MS) measurements have become widely used in the sedimentology of rocks from the Recent to the Paleozoic. The basic principle of the technique is the following: MS measurements on sedimentary rocks are considered as a proxy for impurities delivered to the sedimentary environments. Although the common sandstones or limestones have very low magnetic response, many weathering products coming from the erosion of the main land commonly have high MS values. So the measurement of MS in sediment is considered as a proxy for such detrital input. This relationship is interesting because it is hypothetized that climatic and eustatic sea level variations will affect the detrital input. A sea-level fall increases the proportion of exposed continent and siliciclastic supply and therefore increases magnetic mineral deposition. Furthermore, an increase of rainfall or a glaciation will also increase erosion. Bulk MS measurements have been used in sedimentology for correlations and for reconstruction of sea level or climatic changes.
MS of Holocene, Pleistocene, and Tertiary sediments and sedimentary rocks is widely used as a paleoclimatic proxy. The use of MS in Paleozoic sediments is becoming more common but still suffers from some controversy. One of the problems is the origin of the magnetic minerals. The dominant hypothesis for sedimentologists is that magnetic minerals are mainly related to lithogenic inputs. But are these related to fluvial or eolian sources? Are these lithogenic input variations related to climatic, sea level or tectonic changes? These different influences are probably acting at different time-scales and to differentiate the different impacts, a strong interdisciplinary characterization of facies, cyclostratigraphy and the MS signal and it's carriers is needed. Furthermore, considering the study of Paleozoic rocks, the influence of diagenesis in creating or destroying magnetic minerals has to be assessed.
In order to solve these issues, an efficient and truly international collaboration between geoscientists from various disciplines like sedimentology, paleontology, stratigraphy, paleoclimatology, geochemistry, paleomagnetism and geophysics should be initiated and encouraged.
This website intend to propose a platform between researchers interested in magnetic susceptibility problems, with a data base of people working on magnetic susceptibility and the material they are working on (location, age, purpose,...). To fill out the website (to ad your material, or link to your website, you can feel the appropriate form.
This website will aslo propose links to the main laboratories interested in magnetic susceptibility and to meetings or events related to MS.