The mystery of the missing deglacial carbonate preservation maximum

Glacial deep ocean sequestration of CO2 driven by the eastern equatorial Pacific biologic pump

“…Instead, MFI-based calcite preservation data from RC13-140, RC23-22, and RC23-15 (Fig. 8) corroborate previous application of this novel proxy in the deep EEP by revealing the unanticipated trend of increasing dissolution over the deglacial interval (Mekik et al, 2012). Dissolution intensity is highest by 10 ka BP (coincident with the most elevated CO 3 2− ), and does not return to glacial low values during the Holocene.…”

“…There remains considerable discrepancy between the absolute magnitude of vertical flux estimates derived from 14 C age-model MARs versus 230 Th normalized MARs. However, there is an emerging overall picture in the EEP of: (1) higher Marine Isotope Stage (MIS) 2 C org flux relative to the Holocene with a deglacial peak (Pedersen, 1983;Lyle, 1988;Kienast et al, 2007;Pichevin et al, 2009); (2) lower MIS 2 opal flux relative to the Holocene with a deglacial peak (Bradtmiller et al, 2006(Bradtmiller et al, , 2010Kienast et al, 2006;Warnock et al, 2007;Pichevin et al, 2009;Dubois et al, 2010;Calvo et al, 2011); and (3) constant or lower absolute MIS 2 CaCO 3 flux relative to the Holocene with a slight deglacial peak and better MIS 2 preservation (Loubere, 2004;Loubere and Richaud, 2007;Richaud et al, 2007;Mekik et al, 2012). High MIS 2 C org may be reconciled with low opal if Fe-fertilization decreased the diatom utilization ratio of Si:C and/or increased the solubility of frustules (Watson et al, 2000;Warnock et al, 2007;Pichevin et al, 2009;Dubois et al, 2010).…”

“…Downcore percent calcite dissolved, obtained using the G. menardii fragmentation index (MFI) dissolution proxy developed byMekik et al (2010Mekik et al ( , 2012. MFI is defined as the ratio of whole to damaged G. menardii in the >150 μm size fraction of a core sample.…”

On the potential role of marine calcifiers in glacial‐interglacial dynamics

“…For a compilation of 31 cores from the Pacific, Atlantic, and Indian Oceans, Mekik et al . [] have attempted to tease apart the effects of accumulation and preservation at the last deglaciation, estimating CaCO 3 accumulation rates with 230 Th normalization [ François et al ., ] and using the Globorotalia menardii fragmentation index [ Ku and Oba , ; Mekik et al ., , ] as a proxy of preservation. Most of these cores exhibit a deglacial maximum in calcite accumulation, but not in preservation.…”

The [simple carbon project] model v1.0

“…The latter is an important part of the oceanic carbon and alkalinity cycles and provides important feedbacks to atmospheric CO 2 on thousand year timeframes (e.g. Farrell and Prell, 1989;Anderson et al, 2007;Mekik et al, 2012;Yu et al, 2014b). …”