ABSTRACT

Linear correlations between Al₂O₃ and ΣREE (14 REEs) are defined for post-Archean fine-grained clastic sedimentary rocks from the Qinling region, Central China and Australia: ΣREE = −16(±71) + 12Al₂O₃, and for Archean fine-grained clastic sedimentary rocks worldwide: ΣREE = −78(±78) + 12Al₂O₃. One important property of such correlations is the additivity, i.e., the correlation equation for ΣREE is equal to the sum of the correlation equations for individual REE, and each REE shows a roughly constant slope. These correlations indicate that the REE of fine-grained clastic sedimentary rocks or metamorphosed equivalents are in general dominantly contained in clay minerals or their metamorphosed products. Using these correlations, the REE abundances of the upper continental crust, sedimentary cover and Devonian strata were calculated for different tectonic units of the Qinling region. The results generally agree with the estimate from direct sampling within 18%.