Please use this identifier to cite or link to this item: http://hdl.handle.net/2122/904
AuthorsBoni, M.* 
Dinarès-Turell, J.* 
Sagnotti, L.* 
TitlePaleomagnetic dating of non-sulfide Zn-Pb ores in SW Sardinia (Italy): a first attempt
Issue Date2005
Series/Report no.48 (2)
URIhttp://hdl.handle.net/2122/904
Keywordspaleomagnetism
non-sulfideores
calamine
Sardinia
Subject Classification04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism 
AbstractA first paleomagnetic investigation aimed at constraining the age of the non-sulfide Zn-Pb ore deposits in the Iglesiente district (SW Sardinia, Italy) was carried out. In these ores, the oxidation of primary sulfides, hosted in Cambrian carbonate rocks, was related to several paleoweathering episodes spanning from the Mesozoic onward. Paleomagnetic analyses were performed on 43 cores from 4 different localities, containing: a) non-oxidized primary sulfides and host rock, b) oxidized Fe-rich hydrothermal dolomites and (c) supergene oxidation ore («Calamine»). Reliable data were obtained from 18 samples; the others show uninterpretable results due to low magnetic intensity or to scattered demagnetization trajectories. Three of them show a scattered Characteristic Remanent Magnetization (ChRM), likely carried by the original (i.e. Paleozoic) magnetic iron sulfides. The remaining 15 samples show a well defined and coherent ChRM, carried by high-coercivity minerals, acquired after the last phase of counterclockwise rotation of Sardinia (that is after 16 Myr), in a time interval long enough to span at least one reversal of the geomagnetic field. Hematite is the main magnetic carrier in the limestone, whereas weathered hydrothermal dolomite contains goethite or a mixture of both. The results suggest that paleomagnetism can be used to constrain the timing of oxidation in supergene-enriched ores.
Appears in Collections:Annals of Geophysics

Files in This Item:
File Description SizeFormat 
08Boni.pdf1.19 MBAdobe PDFView/Open
Show full item record

Page view(s)

108
checked on May 24, 2017

Download(s)

159
checked on May 24, 2017

Google ScholarTM

Check