Geochemical facies analysis of fine-grained siliciclastics using Th/U, Zr/Rb and (Zr+Rb)/Sr ratios

Dypvik, Henning; Harris, Nicholas B.

doi:10.1016/s0009-2541(01)00278-9

Cited by 289 publications

(156 citation statements)

References 19 publications

Supporting

Mentioning

152

Contrasting

Order By: Relevance

“…Cu, Zn, Rb, Cs, Ba and Sn are generally related to clay minerals (Vital and Stattegger, 2000). Fine-grained sediments typically show high Rb counts (Dypvik and Harris, 2001), which is also documented in varved sections of PS1795, where Rb similar to K, Fe, and Ti is enriched in the darker, finer-grained layers (Fig. 4).…”

Section: Element Compositionmentioning

confidence: 76%

Seasonal changes in glacial polynya activity inferred from Weddell Sea varves

et al. 2014

View full text Add to dashboard Cite

Abstract. The Weddell Sea and the associated FilchnerRønne Ice Shelf constitute key regions for global bottomwater production today. However, little is known about bottom-water production under different climate and icesheet conditions. Therefore, we studied core PS1795, which consists primarily of fine-grained siliciclastic varves that were deposited on contourite ridges in the southeastern Weddell Sea during the Last Glacial Maximum (LGM). We conducted high-resolution X-ray fluorescence (XRF) analysis and grain-size measurements with the RADIUS tool (Seelos and Sirocko, 2005) using thin sections to characterize the two seasonal components of the varves at sub-mm resolution to distinguish the seasonal components of the varves.Bright layers contain coarser grains that can mainly be identified as quartz in the medium-to-coarse silt grain size. They also contain higher amounts of Si, Zr, Ca, and Sr, as well as more ice-rafted debris (IRD). Dark layers, on the other hand, contain finer particles such as mica and clay minerals from the chlorite and illite groups. In addition, Fe, Ti, Rb, and K are elevated. Based on these findings as well as on previous analyses on neighbouring cores, we propose a model of enhanced thermohaline convection in front of a grounded ice sheet that is supported by seasonally variable coastal polynya activity during the LGM. Accordingly, katabatic (i.e. offshore blowing) winds removed sea ice from the ice edge, leading to coastal polynya formation. We suggest that glacial processes were similar to today with stronger katabatic winds and enhanced coastal polynya activity during the winter season. Under these conditions, lighter coarser-grained layers are likely glacial winter deposits, when brine rejection was increased, leading to enhanced bottom-water formation and increased sediment transport. Vice versa, darker finer-grained layers were then deposited during less windier season, mainly during summer, when coastal polynya activity was likely reduced.

show abstract

Section: Element Compositionmentioning

confidence: 76%

Seasonal changes in glacial polynya activity inferred from Weddell Sea varves

et al. 2014

View full text Add to dashboard Cite

show abstract

“…The presence of a well-developed MGP promoted intense sea ice formation during winter and enhanced brine-induced convection. Variations in bottom current velocities were estimated from changes in sediment grain size inferred from Zirconium versus Rubidium (Zr/Rb) relative abundances 20 . Assuming that greater deep-reaching convection is associated with intensified bottom currents, the high Zr/Rb ratios ( Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Indeed, in Antarctic coastal areas, delivery of terrigenous particles is possible via several dominant modes as meltwater discharge, ice rafting, runoff from outlet glaciers and aeolian transport, although this latter source is considered negligible in coastal East Antarctic regions [17][18][19] . Variations in Zr to Rb content ratio track changes in sediment grain size, where Zr represents the coarsest sediment fraction and Rb represents the finest 20 . Ti, Zr and Rb contents were measured on slab sections at a 2 mm resolution along the entire core using an AAVATECH XRF core-scanner 67 .…”

Section: Methodsmentioning

confidence: 99%

Glacial ice and atmospheric forcing on the Mertz Glacier Polynya over the past 250 years

et al. 2015

View full text Add to dashboard Cite

The Mertz Glacier Polynya off George V Land, East Antarctica, is a source of Adélie Land Bottom Water, which contributes up to B25% of the Antarctic Bottom Water. This major polynya is closely linked to the presence of the Mertz Glacier Tongue that traps pack ice upstream. In 2010, the Mertz Glacier calved a massive iceberg, deeply impacting local sea ice conditions and dense shelf water formation. Here we provide the first detailed 250-year long reconstruction of local sea ice and bottom water conditions. Spectral analysis of the data sets reveals large and abrupt changes in sea surface and bottom water conditions with a B70-year cyclicity, associated with the Mertz Glacier Tongue calving and regrowth dynamics. Geological data and atmospheric reanalysis, however, suggest that sea ice conditions in the polynya were also very sensitive to changes in surface winds in relation to the recent intensification of the Southern Annular Mode.

show abstract

“…4). A similar effect is common in sedimentary environments (Fralick and Kronberg, 1997;Dypvik and Harris, 2001;García et al, 2004), and is related to the action of bottom currents that selectively remove the fine grain size fraction and concentrate the heavy minerals. In general, trace metals do not reach very high concentrations, except Pb in core GL3, which reaches maximum concentrations of 65 mg kg -1 (Fig.…”

Section: Sediment Geochemistrymentioning

confidence: 81%

Sediment geochemistry and accumulation rates on the northeastern shelf of the Gulf of Cádiz (SW Iberian Peninsula)

Guerra¹,

Dinelli²,

Righi³

et al. 2010

Sci. Mar.

View full text Add to dashboard Cite

SUMMARY: Geochemistry, total organic carbon and total nitrogen of three sediment cores collected in the Gulf of Cádiz and the Guadalquivir prodelta areas in Spain were investigated. The C/N ratio, mostly around 10, seems to indicate a predominantly marine origin for the sedimentary organic matter. Major and minor elements (Si, Ti, Al, Fe, Mg, Ca, K, Na, P, S) and trace elements (Mn, Sc, V, Cr, Ni, Cu, Zn, Rb, Sr, Y, Zr, Ba, Ce, Pb, Hg) showed significant differences in bulk chemical composition between the two areas. Despite the effects of bioturbation, vertical changes in downcore profiles of heavy metals occur only in the cores of the Cádiz area, although the concentrations keep to low levels. The relatively high concentrations of Zr and Y, elements commonly associated with the heavy minerals fraction, at the top of cores from the Cádiz area are attributed to an enrichment of heavy minerals related to selective transport that concentrates this fraction. 137 Cs and 210 Pb activities in one of the two sediment cores collected in the Gulf of Cádiz were also measured. The distribution of excess 210 Pb was used to determine the modern (last 100 yr) mass accumulation rate and the depth of sediment mixing on the continental shelf of the gulf. Estimated sediment accumulation rate was 0.1 g cm -2 yr -1 . The uppermost 4 cm had uniform excess 210 Pb activity profiles above a region of steadily decreasing 210 Pb activity, and this phenomenon was attributed to sediment mixing (bioturbation). 137 Cs activity was lower than 3 Bq kg -1 and the profile does not show evidence of fallout peaks.

show abstract

Geochemical facies analysis of fine-grained siliciclastics using Th/U, Zr/Rb and (Zr+Rb)/Sr ratios

Cited by 289 publications

References 19 publications

Seasonal changes in glacial polynya activity inferred from Weddell Sea varves

Seasonal changes in glacial polynya activity inferred from Weddell Sea varves

Glacial ice and atmospheric forcing on the Mertz Glacier Polynya over the past 250 years

Sediment geochemistry and accumulation rates on the northeastern shelf of the Gulf of Cádiz (SW Iberian Peninsula)

Contact Info

Product

Resources

About