(Appendix) Oxygen isotope record and carbonate mineralogy of the top part of ODP Hole 101-633A

• Main Authors: Droxler, André W, Bruce, Christopher H, Sager, William W, Watkins, David H
• Format: Dataset
• Language: English
• Published: PANGAEA 1988
• Subjects: 101-633A; Aragonite; Calcite; Carbonate bomb (Müller & Gastner; 1971); Carbonates; Depth; bottom/max; sediment/rock; top/min; Dolomite; DRILL; Drilling/drill rig; DSDP/ODP/IODP sample designation; Globigerinoides rubra; δ18O; Globigerinoides sacculifer; Grain size; sieving; Isotope ratio mass spectrometry; Joides Resolution; Leg101; Magnesium-Calcite; North Atlantic Ocean; Ocean Drilling Program; ODP; Sample code/label; Size fraction > 0.063 mm; sand; X-ray diffraction (XRD); The Toe; North Atlantic
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.742946; https://doi.org/10.1594/PANGAEA.742946

Hole 633A was drilled in the southern part of Exuma Sound on the toe-of-slope of the southeastern part of Great Bahama Bank during ODP Leg 101. The top 55 m, collected as a suite of six approximately 9.5-m-long hydraulic piston cores, represents a Pliocene-Pleistocene sequence of periplatform carbonate ooze, a mixture of pelagic calcite (foraminifer and coccolith tests), some pelagic aragonite (pteropod tests), and bank-derived fine aragonite and magnesian calcite. A 1.6-m.y.-long hiatus was identified at 43.75 mbsf using calcareous nannofossil biostratigraphy and magnetostratigraphy. The 43.75-m-thick periplatform sequence above the hiatus is a complete late Pliocene-Quaternary record of the past 2.15 m.y. The d18O curve, primarily based on Globigerinoides sacculifera, clearly displays high-frequency/low-amplitude cycles during the early Pleistocene and low-frequency/high-amplitude cycles during the middle and late Pleistocene. Variations in aragonite content in the fine fraction of the periplatform ooze show a cyclic pattern throughout the Pleistocene, as previously observed in piston cores of the upper Pleistocene. These variations correlate well with the d18O record: high aragonite corresponds to light interglacial d18O values, and vice versa. Comparison of the d18O record and the aragonite curve helps to identify 23 interglacial and glacial oxygen-isotope stages, corresponding to 10.5 aragonite cycles (labeled A to K) commonly established during the middle and late Pleistocene (0.9 Ma-present). Strictly based on the aragonite curve, another 11 aragonite cycles, labeled L to V, were identified for the early Pleistocene (0.9 to 1.6 Ma). Mismatches between the d18O record and the aragonite curve occur mainly at some of the glacial-to-interglacial transitions, where aragonite increases usually lag behind d18O depletion. When one visually connects the minima on the Pleistocene aragonite curve, low-frequency (0.4 to 0.5 m.y.) supercycles seem to be superimposed on the high-frequency cycles. The timing of this ...