9305272 Bralower In this collaborative, interdisciplinary study, PIs will investigate biostratigraphy, magnetostratigraphy, cyclostratigraphy and stable isotope stratigraphy of a middle Cretaceous marine sequence in northeastern Mexico, representing a time of rapid global change. Issues to be addressed include: 1) presence of correlative oceanic anoxic events, 2) appropriateness of an oxygen- minimum-zone model for this sequence, 3) potential correlation of organic-rich sedimentation with sea-level fluctuations, 4) relationship of organic-carbon burial events to record of carbon isotopes, 5) significance of a brief magnetic reversal during this time, 6) are orbital periodicities recorded in this sequence?, 7) how does the expression of cyclicity change along the basin margin?, 8) timing of evolution of planktonic forams during this time, and 9) how do nannoplankton and planktonic forams respond to events around this time period? Potential drilling sites for Apticore/Albicore will be evaluated. ***