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PALEOCEANOGRAPHY, VOL. 18, NO. 3, 1059, doi:10.1029/2002PA000777, 2003

Neogene carbonate burial in the Pacific Ocean

Mitchell Lyle

Center for Geophysical Investigation of the Shallow Subsurface, Boise State University, Boise, Idaho, USA

Abstract

I have compiled CaCO₃ mass accumulation rates (MARs) for the period 0–25 Ma for 144 Deep Sea Drilling Project and Ocean Drilling Program drill sites in the Pacific in order to investigate the history of CaCO₃ burial in the world's largest ocean basin. This is the first synthesis of data since the beginning of the Ocean Drilling Program. Sedimentation rates, CaCO₃ contents, and bulk density were estimated for 0.5 Myr time intervals from 0 to 14 Ma and for 1 Myr time intervals from 14 to 25 Ma using mostly data from Initial Reports volumes. There is surprisingly little coherence between CaCO₃ MAR time series from different Pacific regions, although regional patterns exist. A transition from high to low CaCO₃ MAR from 23–20 Ma is the only event common to the entire Pacific Ocean. This event is found worldwide. The most likely cause of lowered pelagic carbonate burial is a rising sea-level trend in the early Miocene. The central and eastern equatorial Pacific is the only region with adequate drill site coverage to study carbonate compensation depth (CCD) changes in detail for the entire Neogene. The latitude-dependent decrease in CaCO₃ production away from the equator is an important defining factor of the regional CCD, which shallows away from the equatorial region. Examination of latitudinal transects across the equatorial region is a useful way to separate the effects of changes in carbonate production (“productivity”) from changes in bottom water chemistry (“dissolution”) upon carbonate burial.

Received 20 February 2002; accepted 19 March 2003; published 9 July 2003.

Index Terms: 3099 Marine Geology and Geophysics: General or miscellaneous; 4267 Oceanography: General: Paleoceanography; 4806 Oceanography: Biological and Chemical: Carbon cycling; 4825 Oceanography: Biological and Chemical: Geochemistry; 9355 Information Related to Geographic Region: Pacific Ocean.

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Citation: Lyle, M. (2003), Neogene carbonate burial in the Pacific Ocean, Paleoceanography, 18(3), 1059, doi:10.1029/2002PA000777.

Copyright 2003 by the American Geophysical Union.