Radiogenic isotopes mantle evolution

Radiogenic isotope data have added important information on evolution of mantle sources. The continuous trends of Sr-Nd-Pb isotope ratios along the Italian peninsula, from Etna-Iblei to Tuscany, have been interpreted as a result of contamination of upper mantle by different types of upper... 

A much debated issue in the petrogenesis of Aeolian arc magmatism has been whether mafic magmas with different enrichments in potassium, incompatible elements and radiogenic isotopes are related to each other by some type of shallow level evolution process, or they reflect the occurrence of different types of primaiy melts, possibly derived from composi-tionally variable mantle sources. 

Patchett P. J. (2003) Provenance and crust-mantle evolution studies based on radiogenic isotopes in sedimentary rocks. In Geochemistry of Sediments and Sedimentary Rocks Evolutionary Considerations to Mineral Deposit—Forming Environments, Geological Association of Canada GEOtext (ed. D. R. Lentz). St. John s, Nfld, vol. 5, pp. 89-97. 

Mantle evolution through time -radiogenic isotope constraints... 

Radiogenic isotopes have proved a most powerful tool for understanding mantle processes. By studying mantle peridotites and mantle-derived melts from a variety of different geological time periods it is possible to define evolutionary curves for the different isotopic systems within the mantle. These curves, when plotted on isotope ratio versus time diagrams, can be used to characterize the chemical evolution of the mantle over time. Deviations from the chondritic trend are used to identify chemical fractionation events in the mantle during Earth history. Of particular... 

Each of the different radiogenic isotope systems discussed above provides its own insight into the history of the Earth s mantle. Here these different threads are brought together to provide an overview of mantle evolution through the history of the Earth. 

It has been recognized that the Lu-Hf isotopic system in zircon is a powerful tool for deciphering the evolution of the earth s crust and mantle. " Zircon normally contains 0.5-2 wt % Hf, which results in an extremely low Lu/Hf ratio (" Lu/" Hf < 0.002) and consequently a negligible radiogenic growth of Hf due to the decay of Lu. Therefore, the Hf/" Hf ratio of zircon can be regarded as the initial value at the time when it crystaUized. LA-ICP-MS with a multiple ion collector system has also been employed to study the hafnium isotopic composition of zircon and baddeleyite standards in U-Pb geochronology. °°... 

A distinct class of models that describe the chemical evolution of the Earth are the so-called box models, in which assumptions are made about the geometry of distinct reservoirs and their interactions. For example, one can assign four distinct reservoirs in the upper mantle, lower mantle, continental crust, and atmosphere and develop differential equations that incorporate radiogenic ingrowth, chemical fractionation effects, and assumptions about mass transfer between the reservoirs. Successful models reproduce the observed isotopic ratios and/or... 

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