Neogene Turbidite Sequence on the Madeira Abyssal Plain: Basin Filling and Diagenesis in the Deep Ocean1
Weaver, P.P.E., Schmincke, H.-U., Firth, J.V., and Duffield, W. (Eds.), 1998 Proceedings of the Ocean Drilling Program, Scientific Results, Vol. 157 38. NEOGENE TURBIDITE SEQUENCE ON THE MADEIRA ABYSSAL PLAIN: BASIN FILLING AND DIAGENESIS IN THE DEEP OCEAN1 P.P.E. Weaver,2 I. Jarvis,3 S.M. Lebreiro,2 B. Alibés,4 J. Baraza,4 R. Howe,5 and R.G. Rothwell2 ABSTRACT The Madeira Abyssal Plain (MAP) has been formed by the accumulation of turbidite sediments from three principal sources: the northwest African continental margin, the Canary Islands and the Hyères/Cruiser/Great Meteor seamount chain. Turbidites derived from each of these sources have distinct chemical signatures enabling the development of a high-resolution chemostratigraphy, in addition to the conventional bio- and lithostratigraphies. Individual beds can be up to a few meters thick, and many are traceable across the whole plain. The first turbidites rapidly infilled the fracture zone valleys through the middle Miocene. By 16 Ma, the fracture zones were nearly filled, and flows began to spread across wider areas to form the plain. Between 16 and 13 Ma, individual flows became much larger, so that after this time, correlation of individual beds is possible between Sites 950, 951, and 952, which are spaced 50–60 km apart. Accumulation rates of the three principal groups of turbid- ites increased between 7 and 6.5 Ma, and remain high to the present day. One subgroup, termed “gray nonvolcanic turbidites,” show a pulsed input to the plain, which may be related to the early growth phases of individual Canary Islands.
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