Foraminifera as Proxies for Sea-Level Change on Siliciclastic Margins

Abstract

oxygen minimum zone dynamic coastal and shelf fronts thermocline tidal mixing runoff high energy turbidity daily-seasonal fluctuations in temperature & salinity ± high productivity halocline shelf breakABSTRACT: Foraminifera of siliciclastic and mixed siliciclastic-carbonate continental margins are sensitive to changes in sea level because of the complex biological, chemical, and physical oceanographic variables that help to shape foraminiferal niche space. Data on foraminiferal distribution and abundance provide useful proxies for paleoenvironment. Here we emphasize the importance of salinity, temperature, seasonality, food supply (productivity), and dissolved oxygen in controlling the nature of marginal marine, neritic, and upper bathyal foraminiferal biofacies. We also elaborate on the paleoecologic significance and utility of using planktic:benthic ratios, diversity indices, and similarity coefficients for interpreting changes in relative sea level. The recognition and correlation of the systems tracts that define sequence stratigraphic architecture reliably hinge on multi-proxy micropaleontologic evidence, particularly that provided by benthic and planktic foraminifera, coupled with sedimentology and geochemistry.

Fossil associations from the middle and upper Eocene strata of the Pamplona Basin and surrounding areas (Navarre, western Pyrenees)

“…Pamplona Marl Formation (Figs. 7, 8) Upwards in the sedimentary series of the study area, in the base of the Pamplona Marl Formation, the moderately high proportion of planktic foraminifera and the high diversity and composition of benthic foraminifera, including the presence of agglutinated tubular forms (astrorhizids; Murray et al, 2011), still are indicative of relatively deep-water, outer-platform to upper slope environments (Leckie and Olson, 2003;Murray, 2006). The stalked crinoid Isselicrinus is an extinct genus (Late Cretaceous-Miocene) of wide biogeographic distribution.…”

“…Eastward in the study area and in the uppermost part of the Ilundain Marl Formation, the scarcity of planktic foraminifera and the composition of the moderately diverse benthic foraminifera (including common porcelaneous foraminifera) suggest an inner shelfal depth of deposition (Leckie and Olson, 2003;Murray, 2006).…”

Palaeoenvironmental changes in the Transylvanian Basin during the Early Miocene revealed by the foraminifera assemblages

“…Cattaneo and Steel (2003) as so ci ated the max imum flood ing sur face (MFS) with con densed sec tions show ing re duced ox y gen val ues, high or ganic mat ter con tent, authigenic ma te rial (e.g., glauconite), abun dant and di verse plank ton, and low amounts of ben thic foraminifera. Leckie and Olson (2003) as so ci ated the glauconite rich fine-grained de pos its with the MFS, while Miller et al (1997) as so ci ated the shelly sands with glauconite with transgressive sys tems tracts (TST) de pos ited in in ner-mid dle neritic (0 to 100 m) en vi ron ments. Other au thors re lated the MFS with: grey-brown clays with glauconite (Danielsen et al, 1997), glauconite bear ing de pos its (Christensen et al, 1995), glauconite with peak abun dances of Uvigerina , peaks in to tal or ganic car bon (Miller and Lohmann, 1982) dur ing times of max i mum flood ing (Loutit et al, 1988), or con densed sec tions con tain ing glauconite and/or sid er ite (Posamentier and Allen, 1999;Cãtuneanu, 2006).…”

“…Plank tonic foraminifera are gen er ally ab sent or scarce across much of the in ner and mid dle shelf and their abun dance rap idly in creases across the outer shelf and up per slope (e.g., Phleger, 1951;Grimsdale and van Morkhoven, 1955;Bandy, 1956;Gib son, 1989;Van der Zwaan et al, 1990;Leckie and Olson, 2003). The plank tonic/ben thic ra tio could be in flu enced by var i ous fac tors, such as vari a tions in sa lin ity, pro duc tiv ity, oxy gen a tion and con nec tion with the world oceans (e.g., Ulleberg, 1974;Naidu and Malmgren, 1995;Van Hinsbergen et al, 2005).…”

Site U1389

“…Based on the revealed benthic foraminiferal assemblages, three intervals can be distinguished in the succession that correspond well to lithologic Subunits 1A-1E (see "Lithostratigraphy"): , 1986;Leckie and Olson, 2003;Murray, 2006). Occasional peaks in Cibicidoides spp.…”