“…These techniques include evaluating trace element concentrations and ratios of diagenetically relevant elements (Brand and Veizer, ; Banner, ; Frank, Lohmann, and Meyers, ; Metzger and Fike, ) and have been applied to carbonate δ 13 C and δ 18 O values to eliminate diagenetically altered samples from datasets to improve interpretation of original biogeochemical changes. Other workers have applied statistical techniques such as parametric and non‐parametric statistical models (Oehlert et al , ; Krissansen‐Totton, Buick, and Catling, ), hierarchical cluster analysis (Coimbra, Marques, and Olóriz, ) and principal component analysis (Elek, ; Kazmerczuk and Jarzyna, ; Ma, ; Enikanselu and Ojo, ; Coimbra et al , ; among others) to datasets of elemental and carbon and oxygen isotope stratigraphy in ancient carbonates in order to quantify changes in sediment source, lithology, facies and diagenesis. In many cases, petrographic analysis of carbonate sediments and their cements, as well as core descriptions of sedimentologically relevant surfaces are often incorporated to prevent the interpretation of diagenetically altered samples as pristine records of original changes in the global carbon cycle.…”