The Campi Flegrei area in southern Italy has been volcanically active for at least 50,000 years. Today Campi Flegrei is characterized by numerous low-magnitude earthquakes and continuous fumarolic activity. Associated with this activity is a slow, episodic meter-scale uplift and deflation of the ground surface that is referred to as bradyseism. Some researchers associate this ground movement with emplacement of new magma into the inferred magma chamber at depth, and suggest that magma emplacement (and uplift) may presage a future volcanic eruption in this area that is home to over two million people. Periods of uplift and deflation have been documented for over 2000 years, and only in 1538 did an eruption follow a period of uplift. Bodnar et al. propose that periods of uplift at Campi Flegrei are associated with the crystallization of a volatile-bearing magma at depth, and that the energy to lift the ground surface is provided by hydrothermal fluids that boil and expand in the deep subsurface. According to this model, uplift and volcanic activity are not linked, and periods of active bradyseism do not necessarily indicate that an eruption is imminent.
Determining the absolute timing of mineralization is a critical, but problematic, aspect for understanding the origin of metallic ore depositsthe ore minerals in these deposits are not amenable to direct isotope dating using common methods. Morelli et al used radioactive isotope dating, using the rare elements rhenium and osmium (Re-Os) in arsenopyrite, to establish the age of gold mineralization at the giant Muruntau gold deposit, Uzbekistan (>5100 me
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Geological Society of America