The role of the interaction between asthenospheric and lithospheric mantles in the generation of giant Ni--Cu--PGE sulfide deoosits
Continental Flood Basalt (CFB) magmas are ideal candidates for the production of major economic Ni-Cu-PGE magmatic sulfide deposits because they are PGE-undepleted,with most containing 9 to 12 ppb Pd,with the exception of those that have been severely crustally contaminated.Whereas CFB have similar MgO contents to MORB and were produced by similar degrees of partial melting,MORBs are strongly PGE-depleted due to loss of the PGE to immiscible magmatic sulfides that segregated from the S-saturated MORB magmas.Modelling indicates that CFB are unlikely to have been produced in a columnar melting regime from a mantle containing an average of 250 ppm S,the average S content of the asthenospheric mantle;hence,such magmas should be PGE-depleted.It is proposed that the Siberian CFB are PGE-undepleted because they are the products of the interaction of the mantle plume with strongly S-depleted subcontinental lithospheric mantle which,although S-depleted,would not have been PGE-depleted.
Reid R.Keays
School of Geosciences,Monash University,Clayton,3800,Australia
国际会议
贵阳
英文
1-4
2012-06-16（万方平台首次上网日期，不代表论文的发表时间）