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Orbitally-Tuned Sr Isotope Chemostratigraphy For The Late Middle To Late Miocene, E. E. Martin, N. J. Shackleton, J. C. Zachos, Benjamin P. Flower

Marine Science Faculty Publications

We present a Sr chemostratigraphic reference section for the late middle to late Miocene (14-5 Ma) from Ocean Drilling Program site 926 on the Ceara Rise. This site combines a precise, orbitally tuned timescale with a high sedimentation rate (15 m/m.y.), continuous deposition, and excellent biostratigraphic control. The Sr isotope curve is based on measurements of cleaned, planktonic foraminifera at 100-200 kyr sample intervals and it illustrates periods of rapid change in Sr-87/Sr-86 alternating with periods of little change. Chemostratigraphically-defined ages for these intervals can be determined within +/-0.8 m.y. and +/-1.6 m.y, respectively. There is excellent correlation with the …