Please use this identifier to cite or link to this item: http://hdl.handle.net/2122/3887
AuthorsGong, Z.* 
Dekkers, M. J.* 
Dinarès-Turell, J.* 
Mullender, T. A. T.* 
TitleRemagnetization mechanism of lower Cretaceous rocks from the Organyà Basin (Pyrenees, Spain)
Issue Date2008
Series/Report no./ 52 (2008)
URIhttp://hdl.handle.net/2122/3887
Keywordsnatural remanent magnetization
remagnetization mechanism
Cretaceous
Pyrenees
Subject Classification04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport 
04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy 
04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism 
04. Solid Earth::04.05. Geomagnetism::04.05.07. Rock magnetism 
AbstractWidespread Cretaceous remagnetization is documented in several Mesozoic basins in North Central Spain. Organyà Basin (South Central Pyrenean foreland) is atypical in the sense that the lower part of the rock sequence (Berriasian-Barremian limestones) is remagnetized while the upper portion (Aptian-Albian marls) is not (Dinarès-Turell and García-Senz, 2000). Here, this view is confirmed by the analysis of 41 new paleomagnetic sites over the entire basin, so that a 3D view is obtained. Thermoviscous resetting of the natural remanent magnetization can be ruled out, hence the remagnetization is chemical in origin. A positive breccia-test on remagnetized strata constrains the remagnetization age to older than the Paleocene-Eocene, when the backthrust system was active. The remagnetization is argued to have occurred early in the geological history of the Organyà Basin either in the elevated geothermal gradient regime during the syn-rift extension or at the earliest phase of the later compression. Burial is considered the most important cause combined with the lithological effect that limestones are more prone to express remagnetization than marls. The observed pressure solution in the remagnetized limestone is likely associated with the remagnetization, whereas it is unlikely that externally derived fluids have played an important role.
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