| 26 Aug 2026
Why does the Northwest Pacific Ocean (Kamchatka Margin) have a different carbonate time series than the rest of the Pacific? Regional carbonate production is greater than deep Pacific dissolution at the start of interglacials
Abstract. Pleistocene records of sedimentary carbonate from most of the Pacific Ocean have a strong 100-ky cyclicity, attributed for the most part to glacial-interglacial variation in carbonate dissolution. Pleistocene glacial intervals throughout the Pacific Ocean have high CaCO3 burial and preservation and accelerated dissolution in interglacial intervals. Records from the equatorial Pacific, Ontong Java Plateau, Shatsky Rise, and along the California continental margin all have this pattern, attributed to changes in corrosiveness of deep waters in the Pleistocene. Surprisingly, CaCO3 records from the far NW Pacific near Kamchatka (ODP Site 882 and cores nearby) have high CaCO3 during early interglacial intervals and no CaCO3 in the glacials, opposite to the rest of the Pacific. We synthesise evidence to suggest that sea ice and/or low salinity surface waters over Site 882 impairs glacial carbonate production sufficiently so that no CaCO3 is buried during glacial intervals. CaCO3 is found in sediments at the beginnings of interglacial intervals, likely because of changes in surface CaCO3 production as oceans reorganize and the Bering Strait opens to shunt sea ice and low salinity water north into the Arctic. The deposition of CaCO3, consistently associated with interglacial intervals at Site 882, implies that glacial sea ice and the associated low salinity surface layer was a factor affecting NW Pacific carbonate deposition during glacial-interglacial transitions throughout the Pleistocene.
This study provides a solution to a puzzle: why does the Northwest Pacific (Kamchatka Margin) exhibit a carbonate burial signal opposed to the rest of the Pacific Ocean. While standard Pleistocene Pacific records feature high carbonate abundance during glacial intervals due to reduced abyssal dissolution, ODP Site 882 displays pronounced carbonate spikes exclusively during early interglacials and near or total absence during glacials.
The authors present a meticulous re-evaluation of the late Pleistocene record at Site 882. By incorporating a corrected splice, generating high-resolution particulate organic carbon and carbonate profiles and calibrating wet bulk density to biogenic silica, they construct a robust record of mass accumulation rates spanning 650 kyr.
The primary strength of the manuscript lies in its rigorous multi-proxy approach to test deep-water dissolution models. By integrating alkenone-derived sea surface temperatures and C37 alkenone percentages alongside biogenic fluxes, the authors persuasively demonstrate that surface productivity controls—rather than corrosive abyssal waters—drive the regional carbonate anomaly.
Overall, this manuscript is an exemplary piece of paleoceanographic synthesis that resolves an anomalous regional record of carbonate accumulation. I don't have any substantive technical or scientific questions. I do have one stylistic suggestion. In the first sentence of the manuscript the authors define carbonate with “CaCO3” and then proceed in almost the entire rest of the manuscript to use the chemical formula instead of the word “carbonate”. For whatever reason, while I am reading, I say to myself the entire chemical formula, which I find somewhat disruptive. I would much prefer they use the word carbonate rather than the formula for it. It will read more smoothly.