Late Cretaceous sea-level changes in Tunisia: A multi-disciplinary approach

A multi-disciplinary study of sea-level and climate proxies, including bulk rock and clay mineral compositions, carbon isotopes, total organic carbon (TOC), Sr/Ca ratios, and macro- and microfaunal associations, reveals seven major sea-level regressions in the southwestern Tethys during the last 10 million years of the Cretaceous: late Campanian (c. 74.2 Ma, 73.4-72.5 Ma and 72.2-71.7 Ma), early Maastrichtian (70.7-70.3 Ma, 69.6-69.3 Ma, and 68.9-68.3 Ma), and late Maastrichtian (65.45-65.3 Ma). Low sea levels are generally associated with increased terrigenous influx, low kaolinite/chlorite+mica ratios, high TOC and high Sr/Ca ratios, whereas high sea levels are generally associated with the reverse conditions. These sea-level changes may be interpreted as eustatic as suggested by the global recognition of at least four of the seven major regressions identified (74.2 Ma, 70.7-70.3 Ma, 68.9-68.3 Ma and 65.45-65.3 Ma). Climatic changes inferred from clay mineral contents correlate with sea-level changes: warm or humid climates accompany high sea levels and cooler or arid climates generally accompany low sea levels.