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Climate of the Past An interactive open-access journal of the European Geosciences Union
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© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 07 Dec 2018

Research article | 07 Dec 2018

Review status
This discussion paper is a preprint. A revision of the manuscript is under review for the journal Climate of the Past (CP).

Late Miocene to Recent High Resolution Eastern Equatorial Pacific Carbonate Records: Stratigraphy linked by dissolution and paleoproductivity

Mitchell Lyle1, Anna Joy Drury2, Jun Tian3, Roy Wilkens4, and Thomas Westerhold2 Mitchell Lyle et al.
  • 1College of Earth, Ocean, and Atmospheric Science, Oregon State University, 104 CEOAS Admin Bldg, Corvallis, Oregon 97331, USA
  • 2MARUM-Center for Marine Environmental Sciences, University of Bremen, Leobener Strasse, 28359 Bremen, Germany
  • 3Laboratory of Marine Geology, Tongji University, Siping Road 1239, Shanghai 200092, PR China
  • 4University of Hawaii, School of Ocean and Earth Science and Technology, Honolulu Hawaii 96822, USA

Abstract. We report late Miocene-Recent time series of XRF-derived bulk sediment composition and mass accumulation rates (MAR) from IODP Sites U1335, U1337, U1338 and ODP Site 849, and also report bulk density-derived CaCO3 MAR at Sites 848, 850 and 851. We use physical properties and images to intercorrelate all records for the last 8 Myr with resolutions of 1–2 kyr. Large magnitude changes in CaCO3 and opal MAR occurred within that time period but clay deposition has remained relatively constant. Ratios of CaCO3 % or SiO2 % to clay can be used to emulate biogenic MAR. We define 5 major Plio-Pleistocene Low CaCO3 % (PPLC) intervals since 5.3 Ma. Two were caused primarily by high opal burial that diluted CaCO3 (PPLC-2—1685-2135 ka, and PPLC-5—4465-4737 ka), while 3 were caused by enhanced dissolution of CaCO3 (PPLC-1—51-402 ka, PPLC-3—2248-2684 ka, and PPLC-4—2915-4093 ka). Regional patterns of CaCO3 % minima can distinguish between lows caused by high diatom production versus lows caused by dissolution. High diatom production causes lowest CaCO3 % at equatorial locations, while higher dissolution causes lowest CaCO3 at higher latitudes. The dissolution interval PPLC-4 occurs as the Central American Seaway closed and during a long decline from extreme positive Atlantic-Pacific carbon isotope gradients indicating an abyssal Pacific buildup of uncompensated DIC in the early Pliocene. The two major post-Miocene production intervals, PPLC-2 and PPLC-5, have different geographic footprints because of regional changes in eastern Pacific nutrient storage after the closure of the Panama Seaway.

Mitchell Lyle et al.
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Mitchell Lyle et al.
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Publications Copernicus
Short summary
Ocean sediment records document changes in Earth's carbon cycle and ocean productivity. We present 8 Myr CaCO3 and bulk sediment records matched from 7 eastern Pacific scientific drill sites to identify intervals of excess CaCO3 dissolution (high carbon storage in the oceans) and excess burial of plankton hard parts indicating high productivity. We define the regional extent of production intervals and explore the impact of the closure of the Atlantic-Pacific Panama connection on CaCO3 burial.
Ocean sediment records document changes in Earth's carbon cycle and ocean productivity. We...