Influence of Carbonate Dissolution, Climate, Sea-Level Changes and Volcanism on Neogene Sediments off Northwest Africa (Leg 41) [chapter]

L. Diester-Haass
1978 Initial Reports of the Deep Sea Drilling Project  
A coarse fraction analysis (>40 µm),has been carried out on the Neogene sediments from Sites 366, 367, 368, and 369 of Leg 41, and the percentage composition of the coarse fractions is given. Influence of calcium carbonate dissolution, shown by the degree of fragmentation of planktonic foraminifers and by plankton/benthos ratios of foraminifers, reveals parallel variations at Sites 366 and 369, with a maximum of dissolution in the upper middle Miocene and a minimum in the Plio-Pleistocene
more » ... ns. Description of Neogene climatic variations is based on the amount of terrigenous material and desert quartz numbers in the fracions >40 µm of Site 369. Early and middle Miocene climate in the Sahara at the latitude of Site 369 has been arid. From late Miocene to Pleistocene, climate has been similar to that during late Quaternary, with alternations of arid climate and more humid climate with greater rainfall and river supply. Sea level was probably considerably lower than today during the early Miocene and perhaps during a short period of the late Miocene. Volcanic glass and ash layers in Site 369 can be correlated with known phases of volcanic activity on the Canary Islands.
doi:10.2973/dsdp.proc.41.139.1978 fatcat:mdkbonazvbgklnodjgjgd2hv3q