MAJOR AND REDOX SENSITIVE TRACE ELEMENTS AS INDICATORS OF PALEOENVIRONMENTAL CONDITIONS IN APTIAN SEDIMENTS DURING OAE1A OF THE CUCHIA SECTION, CANTABRIA, NORTHERN SPAIN
Major elements (Al, Ti, and Si) show increasing values during periods of high TOC (r > 0.5). Similarly, RSTEs (V, Cr, Th, and U) values increase at intervals of higher TOC and show strong positive correlations with TOC (r > 0.5). These increased RSTEs and major elements values occur mostly in the shale and calcareous shale layers with values as high as 88006 (Al), 205916 (Si), 3856 (Ti), 101 (V), 80 (Cr), and 3.8 (U) (concentrations in ppm). However, RSTEs such as Cu, Co, Ni, and Mo, have weak or no apparent correlation with TOC. Phosphorous, a biolimiting trace element also shows no apparent correlation with TOC or any of the other trace elements and has values between 172 and 891 ppm. Strong positive correlations between TOC and the major trace elements suggests that the preservation of organic matter is likely due to rapid burial of organic material by terrestrially derived clays, and is less likely due to reducing conditions as attested by the lack of correlation between TOC and most RSTEs.