3.3.4.2. Palaeoclimatic reconstruction from terrigenous material

Weathering and erosion processes in different climatic zones on the continental land masses may produce characteristic inorganic products. When these are carried to the oceans (by wind, rivers or floating ice) and deposited on the ocean floor, they convey information about the climate of their origin or transportation route, at the time of deposition (e.g. Kolla et al., 1979).

Terrestrial detritus dilutes the relatively constant influx of calcium carbonate; the “purity” of a calcareous ooze shows an inverse relationship with the influx of terrestrial material. Because terrestrial influx is related to climatic factors, the “purity” of calcareous sediments therefore provides a palaeoclimatic indicator (e.g. Hays & Perruzza, 1972). Hence times of high carbonate abundance indicate low terrestrial influx, i.e. low rates of continental weathering. Conversely, carbonate minima correspond to increased levels of continental weathering.