Miocene stable isotope record of IODP Site 320-U1335 and revised stable isotope record of IODP Site 321-U1337

The Miocene Climatic Optimum (MCO; ~16.9 to 14.7 Ma) provides an outstanding opportunity to investigate climate-carbon cycle dynamics during a geologically recent interval of global warmth. We present benthic stable oxygen (d18O) and carbon (d13C) isotope records (5-12 kyr time resolution) spanning the late early to middle Miocene interval (18 to 13 Ma) at Integrated Ocean Drilling Program (IODP) Site U1335 (eastern equatorial Pacific Ocean). The U1335 stable isotope series track the onset and development of the MCO as well as the transitional climatic phase culminating with global cooling and expansion of the East Antarctic ice-sheet at ~13.8 Ma. We integrate these new data with published stable isotope, geomagnetic polarity and X-ray fluorescence (XRF) scanner-derived carbonate records from IODP Sites U1335, U1336, U1337 and U1338 on a consistent, astronomically-tuned timescale. Benthic isotope and XRF scanner-derived CaCO3 records depict prominent 100 kyr variability with 400 kyr cyclicity additionally imprinted on d13C and CaCO3 records, pointing to a tight coupling between the marine carbon cycle and climate variations. Our inter-site comparison further indicates that the lysocline behaved in highly dynamic manner throughout the MCO, with >75% carbonate loss occurring at paleo-depths ranging from ~3.4 to ~4 km in the eastern equatorial Pacific Ocean. Carbonate dissolution maxima coincide with warm phases (d18O minima) and d13C decreases, implying that climate-carbon cycle feedbacks fundamentally differed from the late Pleistocene glacial-interglacial pattern, where dissolution maxima correspond to d13C maxima and d18O minima. Carbonate dissolution cycles during the MCO were, thus, more similar to Paleogene hyperthermal patterns.

Raw and normalized X-ray fluorescence (XRF) scannings of IODP Expedition 321, Site U1338

We used X-ray fluorescence (XRF) scanning on Site U1338 sediments from Integrated Ocean Drilling Program Expedition 321 to measure sediment geochemical compositions at 2.5 cm resolution for the 450 m of the Site U1338 spliced sediment column. This spatial resolution is equivalent to ~2 k.y. age sampling in the 0-5 Ma section and ~1 k.y. resolution from 5 to 17 Ma. Here we report the data and describe data acquisition conditions to measure Al, Si, K, Ca, Ti, Fe, Mn, and Ba in the solid phase. We also describe a method to convert the data from volume-based raw XRF scan data to a normalized mass measurement ready for calibration by other geochemical methods. Both the raw and normalized data are reported along the Site U1338 splice.