Malone, Mitchell J.; Slowey, Niall C.; Henderson, Gideon M. (2001): Early diagenesis of shallow-water periplatform carbonate sediments, leeward margin, Great Bahama Bank (Ocean Drilling Program Leg 166). Geological Society of America (GSA), Boulder, CO, United States, Geological Society of America Bulletin, 113 (7), 881-894, georefid:2001-049728

Abstract:
Mineralogic, petrographic, and geochemical analyses of sediments recovered from two Leg 166 Ocean Drilling Program cores on the western slope of Great Bahama Bank (308 m and 437 m water depth) are used to characterize early marine diagenesis of these shallow-water, periplatform carbonates. The most pronounced diagenetic products are well-lithified intervals found almost exclusively in glacial lowstand deposits and interpreted to have formed at or near the seafloor (i.e., hardgrounds). Hardground cements are composed of high-Mg calcite ( approximately 14 mol% MgCO (sub 3) ), and exhibit textures typically associated with seafloor cementation. Geochemically, hardgrounds are characterized by increased delta (super 18) O and Mg contents and decreased delta (super 13) C, Sr, and Na contents relative to their less lithified counterparts. Despite being deposited in shallow waters that are supersaturated with the common carbonate minerals, it is clear that these sediments are also undergoing shallow subsurface diagenesis. Calculation of saturation states shows that pore waters become undersaturated with aragonite within the upper 10 m at both sites. Dissolution, and likely recrystallization, of metastable carbonates is manifested by increases in interstitial water Sr and Sr/Ca profiles with depth. We infer that the reduction in mineral saturation states and subsequent dissolution are being driven by the oxidation of organic matter in this Fe-poor carbonate system. Precipitation of burial diagenetic phases is indicated by the down-core appearance of dolomite and corresponding decrease in interstitial water Mg, and the presence of low-Mg calcite cements observed in scanning electron microscope photomicrographs.
Coverage:
West: -79.0501 East: -79.0300 North: 23.3650 South: 23.3638
Relations:
Expedition: 166
Site: 166-1008
Site: 166-1009
Supplemental Information:
With GSA Data Repository Item 2001077
Data access:
Provider: SEDIS Publication Catalogue
Data set link: http://sedis.iodp.org/pub-catalogue/index.php?id=2001-049728 (c.f. for more detailed metadata)
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