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Source : Croudace, I.W., Rothwell, R.G. (Eds.), 2015. Micro-XRF Studies of Sediment Cores, Developments in Paleoenvironmental Research. Springer Netherlands, Dordrecht.

Calcium (Ca)

Origin

May be biogenic or detrital, although biogenic sources are volumetrically of far greater importance. Ca as CaCO3 is used as test material for ubiquitous groups of marine plankton, principally foraminifers and coccolithophorids Integral Ca is a recognised proxy for oceanic productivity and Ca variation typically reflects CaCO3 stratigraphy in pelagic cores. Detrital sources may be important in near-shore and estuarine waters, e.g. Rebolledo et al. (2008) found about half the Ca content in some Chilean Fjord sediment related to carbonates with rest derived from weathering of plagioclases in fjord watershed

Use

Ca typically anti-correlates with Fe and other terrigenous elements (e.g. MacLeod et al. 2001) as climatic modulation of productivity typically leads to low Ca during glacials and higher values during interglacials (e.g. Arz et al. 2001b, 2003; Gebhardt et al. 2008; Rooij van et al. 2007). Thus Ca is commonly an effective climatic indicator and efficient for establishing stratigraphic frameworks (e.g. Jorry et al. 2011; Kwiecien et al. 2008). Lower Ca may correlate with carbonate dissolution and/or dilution by terrigenous material. Ca dissolution can provide a proxy for bottom-water corrosiveness (especially if supported by foraminifer dissolution) and hence alkalinity (e.g. Gebhardt et al. 2008) and relate to oceanic water mass changes (e.g. Arz et al. 2001a). Detrital origin of Ca may be inferred by correlation with Fe (e.g. Röhl et al. 2004) to see if Ca mirrors terrigenous supply. Biogenic and detrital carbonate may be distinguished by Ca/Sr, as Sr fixed by calcifying organisms at same time as Ca and so can be used as marker of biogenic origin. Co-variation of Ca and Sr suggests Ca is mainly sourced from biogenic CaCO3 (e.g. Carlson et al. 2008) Limitations: Ca variation, particularly in marginal environments, may reflect dilution by terrigenous material rather than productivity changes Revel et al. (2010) found low Ca during pluvial periods in a core from Nile margin, interpreted as mainly due to terrigenous dilution. A carbonate-rich facies, occurring systematically during glacial/arid periods was characterized by drastic decrease in accumulation rate, interpreted as reflecting significant reduction in Nile flood intensity Quantifying Ca counts: Ca counts can be converted to CaCO3 concentrations by analysis of discrete samples and regression analysis López-Martínez et al. (2006) converted Ca intensities to CaCO3 concentrations (wt.%) by applying regression equation derived from linear correlation (r = 0.94) of scanner measurements and 100 CaCO3 LECO analyses on discrete samples in Late Pleistocene cores from ODP Site 1060 (Blake Outer Ridge, NE Atlantic). CaCO3 content related to productivity. Changes in CaCO3 at ODP Site 1060 showed Dansgaard/Oeschger pattern with higher values during Greenland interstadials

Applications and literature

• Calcium carbonate stratigraphy Coolen et al. (2009); Dorschel et al. (2007); Foubert and Henriet (2009); Henrich et al. (2010); Hibbert et al. (2010); Kwiecien et al. (2008); Risebrobakken et al. (2006); Rebolledo et al. (2008); Ziegler et al. (2009) • Marine productivity Cheshire et al. (2005); Ren et al. (2009); Solignac et al. (2011) • Climate studies Arz et al. (2001b, 2003); Gebhardt et al. (2008); Jorry et al. (2011); Kim et al. (2010); Rooij van et al. (2007); Rebolledo et al. (2008) • Carbonate dissolution and dilution • Bottom-water corrosiveness/alkalinity • Oceanic water mass changes Arz et al. (2001a); Gebhardt et al. (2008); Röhl et al. (2000) • Detrital supply of Ca Abrantes et al. (2008); Carlson et al. (2008); Röhl et al. (2004) • Pteropod preservation and hinterland climate Bourget et al. (2011); Klöcker and Henrich (2006); Pourmand et al. (2004); Prins et al. (2000); Sirocko et al. (1996)

Ca/Fe

Use

Ca/Fe reflects biogenic carbonate:detrital clay ratio and is widely used to determine carbonate stratigraphy and productivity in pelagic cores.Also used to distinguish pelagic and re-deposited muds and assess textural character in turbidite-containing sequences (Rothwell et al. 2006). These two elements reflect marine production and terrigenous input respectively. Primary use of Ca/Fe is as proxy for terrigenous sediment delivery (Fe) compared to marineorigin Ca (e.g. Nizou et al. 2010) although care is needed as Fe is redox-sensitive. Co-variance of Fe and other terrigenous indicators (e.g. Ti, K) will show relative importance of diagenetic effects. Correlation of Ca/Fe excursions with κ anomalies, superimposed on long-term climate signals, may be potentially useful provenance tool (e.g. Peck et al. 2007)

Applications and literature

• Variation in terrigenous sediment delivery McGregor et al. (2009); Nizou et al. (2010); Rogerson et al. (2006b) • Identification of carbonate-rich layers • Sediment provenance • Detection of ice-rafted-debris and tephra Peck et al. (2007); Scourse and Furze (2001) • Core correlation Hanebuth and Lantzsch (2008); Pälike et al. (2001)

Ca/Ca+Fe

Use

Ca/Ca+Fe used by Eisele et al. (2008) to characterise three cores from cold-water coralcovered mound (Galway mound), Porcupine Seabight, SW of Ireland. Ca and Fe amounted to > 90% of all XRF counts, so Ca/Ca+Fe useful benchmark for Ca and Fe. Ca/Ca+Fe showed very similar patterns in all three cores allowing correlation and lithostratigraphic subdivision

Applications and literature

• Core characterisation • Core correlation Eisele et al. (2008)

Ca/Ti

Use

Ca/Ti useful proxy for assessing relative changes in biogenic versus lithogenic sedimentation and recording carbonate content (e.g. Piva et al. 2008). Advantage over Ca/Fe in that Ti is inert

Applications and literature

• Variation in terrigenous sediment delivery Ingram et al. (2010); Piva et al. (2008) • Calcium carbonate content Piva et al. (2008)

Ca/Al

Use

Like Ca/Fe and Ca/Ti, Ca/Al represents the biogenic/detrital ratio so is a potential proxy for measuring changes in terrigenous sediment contribution, providing good Al data can be acquired. Al counts affected by tube type, attenuation in air gap between detector and core surface, water content and presence and thickness of any water layer below protective film covering core. Good Al counts using ITRAX are uncommon when using a Mo tube, but much better with a Cr tube, especially in current generation models. Al detection is good with AVAATECH instrument and may be sufficient for normalisation

Applications and literature

• Data normalisation • Variation in terrigenous sediment delivery Blanchet et al. (2009) • Ocean water mass changes Jaccard et al. (2010)

Ca/K

Use

Ca is proxy for biogenic content and K can be used as proxy for its main mineralogical carrier illite, hence for example, providing potential to map changes in K-rich clay minerals due to varying bottom current strength

Applications and literature

• Changes in K-rich minerals (illite) • Current and water mass changes Hebbeln et al. (2006)

Ca/Sr

Use

Biogenic CaCO3 precipitated by coccoliths and foraminifers has greater Sr than inorganic CaCO3 or dolomite. Hence Ca/Sr may rapidly detect IRD layers rich in detrital carbonate, e.g. some Heinrich layers with larger Ca/Sr ratios when detrital carbonate content high and biogenic CaCO3 is low (Hodell et al. 2008)

Applications and literature

• Detection of detrital carbonate Hodell et al. (2008)

Strontium (Sr)

Use

Sr is an alkaline earth metal fixed by calcifying organisms at same time as Ca. Hence Sr is a marker for biogenic origin. As Ca can be supplied from terrigenous sources (e.g. feldspars and clays) co-variation of Ca and Sr suggests Ca mainly sourced from biogenic CaCO3. Sr is preferentially incorporated into aragonite, hence potentially useful in distinguishing foraminiferal calcite and coralline and/or pteropod aragonite, for example, in cold-water carbonate mounds (e.g. Richter et al. 2006). Sr is efficiently excited using Rh and Mo target tubes, so although frequently a trace element, it produces a good response

Applications and literature

• Discriminating types of carbonate rocks Foubert and Henriet (2009); Richter et al. (2006) • Pteropod abundance • Detection of inorganic aragonitic crusts Arz et al. (2001b, 2003)

Sr/Ca

Use

Sr/Ca has been used as proxy for aragonite, e.g. in onshore massive corals in Madagascar (Grove et al. 2010).Thomson et al. (2006) used Sr/Ca as proxy for aragonite formed due to alkalinity from sulphate reduction within sapropels in E Mediterranean cores. Higher Sr/ Ca values often interpreted as reflecting greater pteropod content (e.g. Krinsley and Bieri 1959). Rothwell et al. (2006) and Thomson et al. (2004) report Sr/Ca peaks in Mediterranean sediments as indicating high Sr aragonite requiring shallow-water source, and Rothwell et al. (2006) describe pelagic intervals containing abundant pteropods registering high Sr/Ca. This may be texturally-related artefact considering reports that pteropod shells in E Mediterranean are low-Sr aragonite (Krinsley and Bieri 1959; Kinsman 1969; Rutten et al. 2000)

Applications and literature

• Proxy for aragonite Grove et al. (2010); Thomson et al. (2006) • Pteropod abundance Krinsley and Bieri (1959); Rothwell et al. (2006)

Iron (Fe)

Origin

Fe is the most common element (by mass) on Earth, forming much of outer and inner core and fourth most abundant element in the crust, after O, Si and Al. Most Fe in the crust is combined with O as Fe oxide minerals like haematite and magnetite. In marine sediments, Fe commonly mirrors changes in carbonate/clay ratios and its high abundance, relatively high signal relative to other elements, and high signal-to-noise ratio makes it a preferred proxy in environmental and process studies. Generally Fe variations relate to the sediment's terrigenous fraction and/or dilution of CaCO3. Fe commonly correlates with other terrigenous markers like Ti but may be less reliable due to redox sensitivity. High Fe in intervals with very low κ suggests magnetite dissolution. Fe may correlate with a* CIELAB colour values as a* is a measure of sediment redness, largely reflecting concentration of Fe (oxides) bearing minerals (e.g. Westerhold et al. 2007) Use: Fe, like Ti, has been widely used to document variations in terrigenous sediment delivery, informing on continental humidity/aridity and precipitation/river run-off changes; or aeolian dust flux/wind strength, all conditions/processes commonly related to climatic forcing (e.g. Vidal et al. 2002; Grützner et al. 2003 and others). As redox-sensitive, Fe can identify secondary diagenetic features or new mineral formation through authigenesis, such as framboid layers (e.g. Seeberg-Elverfeldt et al. 2005). High Fe and S may indicate reducing conditions (e.g. Sluijs et al. 2009). Fe slightly below average shale level, suggests a generally reducing suboxic environmental setting, particularly if with enhanced S, Mn values significantly below average shale level, and high trace element/Al ratios (Sluijs et al. 2008). Fe and Ti are closely related in terrigenous fractions, but Fe is partly prone to diagenetic remobilisation in pore waters. Ti is inert. Hence, good correlation of Fe to Ti suggests little diagenetic influence. Positive correlation of Fe with κ also suggests diagenetic processes are minimal. A smooth decreasing trend in Fe towards core tops has been attributed to dilution due to increasing water content (Mohtadi et al. 2007). Fe and Ti occur predominately in denser lithogenic fraction so may covary with density. Fe (and Ti) can thus be used as negative indices of surface productivity (e.g. Agnihotri et al. 2008)

Applications and literature

• Variation in terrigenous sediment delivery • Hinterland climate • Precipitation and runoff • Aeolian dust flux/wind strength Andres et al. (2003); Arz et al. (1998, 1999, 2001b, 2003); Behling et al. (2000); Bozzano et al. (2002); Foubert and Henriet (2009); Gil et al. (2006); Grützner et al. (2003, 2005); Haug et al. (2001); Henrich et al. (2010); Helmke et al. (2008); Jahn et al. (2003, 2005); Kaiser et al. (2007); Lamy et al. (2001, 2004); Mohtadi et al. (2007); Petersen et al. (2000); Revel et al. (2010); Richter et al. (2001); Vidal et al. (2002); Westerhold (2003); Westerhold et al. (2007) • Changes in carbonate productivity/dissolution • Current and water mass changes Helmke et al. (2005); Holbourn et al. (2007); Norris and Röhl (1999); Röhl et al. (2000, 2001, 2007); Röhl and Abrams (2000); Westerhold and Röhl (2009); Zachos et al. (2001) • Sediment provenance Kaiser et al. (2007); Lamy et al. (2001) • Establishing stratigraphic frameworks Westerhold et al. (2007, 2008) • Diagenetic studies • Authigenesis • Redox conditions Rothwell et al. (2006); Seeberg-Elverfeldt et al. (2005); Sluijs et al. (2008, 2009)

Fe/Ca

Use

Fe and Ca commonly anti-correlate and Fe/Ca quantifies relative proportions of terrigenous fluxes versus marine carbonate, often related to climatic forcing (e.g. Adegbie et al. 2003; Dickson et al. 2010; Rogerson et al. 2006a). Bond et al. (1993) and Bond and Lotti (1995) note close similarity in Fe/Ca in N Atlantic sediments to GRIP and GISP2 ice core records (Grootes et al. 1993; Johnsen et al. 1992) implying direct climatic correspondence of N hemisphere low and high latitudes

Applications and literature

• Variation in terrigenous sediment delivery • Climatic variability • Precipitation and runoff Adegbie et al. (2003); Dickson et al. (2010); Rogerson et al. (2006a)

Fe/Si

Use

A rarely used ratio, but used as proxy for terrigenous influx in Neogene sediments from Ross Sea, Antarctica (Konfirst et al. 2011). Low Fe/Si suggested open marine setting dominated by deposition of diatoms. Transient peaks in Fe/Si correlated with volcanic sands and iron-rich carbonate layers containing authigenic pyrite

Applications and literature

• Terrigenous flux to siliceous pelagic sediments Konfirst et al. (2011)

Fe/Al

Use

Slightly elevated Fe/Al associated with low Si/Al and Ti/Al during PETM at IODP Site M0004 (Lomonosov Ridge) interpreted as possibly indicating more intense weathering (Sluijs et al. 2008). Elevated Fe/Al (with high S, TOC and framboidal pyrite) interpreted as indicating anoxic bottom waters by Spofforth et al. (2008)

Applications and literature

• Weathering intensity Sluijs et al. (2008) • Bottom-water anoxia Spofforth et al. (2008)

Fe/K

Use

Fe and K are both terrigenous indicators and Fe/K has been used in provenance and climate studies (e.g. Kuijpers et al. 2003). Fe/K values in atmospheric Saharan dust samples increase towards the equator (Stuut et al. 2005). Hence increasing amounts of dust from deeply weathered terrains (Moreno et al. 2006) cause increased Fe/K values towards tropics, due to its relatively high Fe content compared to more mobile K (Mulitza et al. 2008) Fluvial sediments in the region contain higher Fe/K values than wind-transported sediments (Gac and Kane 1986; Mulitza et al. 2008; Stuut et al. 2005). As highest water discharge and sedimentary load occurs during rainy seasons (Debenay et al. 1994; Kattan et al. 1987; Lesack et al. 1984) sharp decrease of Fe/K values indicated abrupt onset of arid conditions (Zarriess and Mackensen 2010). Fe/K thus considered indicative of continental rainfall

Applications and literature

• Sediment provenance • Climate variability • Precipitation and runoff • Aeolian dust flux/wind strength Kuijpers et al. (2003); Zarriess et al. (2011); Zarriess and Mackensen (2010)

Fe/K

Use

Fe/magnetic susceptibility (κ) is a sensitive proxy for magnetite diagenesis and Fe reduction (Funk et al. 2004b; Hepp et al. 2009; Hofmann and Fabian 2007; Land et al. 2011). Fe reduction may result in significant magnetic susceptibility signal loss, and zones of enhanced Fe/κ have been shown to correlate with presence of Fe- and Mn oxide/hydroxide coated grains in carbonate mounds (Land et al. 2011). Fe and κ have also been used to identify distinct environmentally significant clusters in cores (Itambi et al. 2009)

Applications and literature

• Iron diagenesis Funk et al. (2004b); Hepp et al. (2009); Hofmann and Fabian (2007); Land et al. (2011) • Sediment transport Itambi et al. (2009)

Fe/Ti

Use

Fe/Ti is used as a proxy for diagenetic iron enrichment (Blanchet et al. 2009; Funk et al. 2004a; Hepp et al. 2009; Land et al. 2011) and for excess Fe over basaltic lithogenic values, with high values suggesting additional sources of Fe-rich material (Marsh et al. 2007). Log ratios of Fe and Ti over Ca have been used to account for dilution by carbonate and non-linearities between XRF counts and elemental concentrations (Rincón‐Martínez et al. 2010)

Applications and literature

• Iron diagenesis Blanchet et al. (2007); Funk et al. (2004b); Hepp et al. (2009); Land et al. (2011) • Variation in terrigenous sediment delivery • Carbonate dilution Marsh et al. (2007); Rincón‐Martínez et al. (2010)

Fe/Zr

Use: Fe/Zr has been used in cores off Mauritania as a proxy for rainfall in the Saharan hinterland (Hanebuth and Lantzsch 2008). Although Zr could not be linked to a specific climatic parameter, a mechanism related to sediment input or distribution was inferred, possibly a transport-and-sorting mechanism separating heavy Zr grains from lighter siliciclastic grains, probably through density-related separation in aeolian and surface water supply. Low Fe/Zr, representing relative enrichment of Zr, occurred at times of aridity, with high values during more humid conditions

Applications and literature

• Precipitation and runoff • Aeolian dust flux/wind strength Hanebuth and Lantzsch (2008)

Fe/Rb

Use

Fe/Rb has been used for Fe normalisation in absence of good Al data (Rothwell et al. 2006). Fe/Rb showed grain-size fractionation effects within turbidites and evidence for diagenetic Fe mobilisation within oxidised upper parts of turbidites. Increased Rb within turbidite muds reflected greater clay contribution to sediment

Applications and literature

• Textural character • Iron diagenesis • Clay content Rothwell et al. (2006)

Aluminium (Al)

Origin

Al is the most abundant metal in the Earth’s crust and third most abundant element, after O and Si, but too reactive to be found pure, and is instead found as oxides and silicates. Aluminosilicates are a major component of kaolin (one of the most common minerals), other clay minerals and zeolites. Other aluminosilicate minerals include andalusite, kyanite, sillimanite, beryl, garnet, spinel, and turquoise. Weathering of low Fe and SiO2 bedrock in tropical climates results in high-alumina clays

Use

Al and Fe have been used as fluvial proxies (Nizou et al. 2011). In this study, Al was preferred for palaeoclimatic analysis due to potential Fe mobility Limitations: Al is routinely used for normalisation of WD-XRF data, but its closeness to core scanner detection limits, rapid attenuation in air and through any sub-film water layer, low response depth, and dependence on tube type may constrain its use in core scanner data normalisation. Al is at the limit of early model ITRAX detection, although detection with current models using a Cr tube is usually good. Al is well detected by AVAATECH instruments with a detection limit of around 2000 ppm in current models Diatoms actively uptake and accumulate Al, so it cannot be used to normalise Ti in diatomaceous sediments (Bennekom et al. 1989; Moran and Moore 1992)

Applications and literature

• Sediment transport • Hinterland climate Nizou et al. (2011)

Al/Si

Use

Al/Si has been used as a proxy for chemical weathering and as a measure of relative proportion of clays compared to quartz sand (Hoang et al. 2010). Clays are rich in Al and this proxy has the advantage of not being affected by large amounts of biogenic carbonate. Decreases in Al/Si signified less chemical weathering

Applications and literature

• Weathering intensity • Weathering processes • Precipitation and runoff • Clay content Hoang et al. (2010)

Al/Ca

Use

Al/Ca used to record terrigenous flux off NW Africa (Nizou et al. 2010, 2011) with low Al/Ca values interpreted as low river discharge indicating hinterland aridity and high Al/ Ca values reflecting humid hinterland phases, use supported by palynological records. To avoid dilution effects, Al/Ca was plotted against time (Weltje and Tjallingii 2008). Water content may influence core scanner measurement for low-atomic-weight elements such as Al (Tjallingii et al. 2007) but Nizou et al. (2011) found little porosity variation downcore (~10 %), hence water influence not considered significant. This analysis was supported by Fe/Ca (two high-atomic weight elements not influenced by water content) which showed same pattern as Al/Ca. When both Al/Ca and Fe/Ca are available, authors conclude Al/Ca is more suitable for recording river runoff as Al is non-mobile

Applications and literature

• Variation in terrigenous sediment delivery • Precipitation and runoff • Hinterland climate Nizou et al. (2010, 2011)

Silicon (Si)

Origin

Measured by mass, Si makes up 27.7 % of Earth’s crust and is the second most abundant element, only O having greater abundance. Si is usually found as complex silicate minerals and less often as quartz (SiO2) a major component of sand and silt derived through physical weathering of continental crust. Silicate minerals comprise the largest and most important class of rock-forming minerals, constituting ~90 % of crustal rocks. Si may be detrital, derived from mechanical weathering of crustal rocks, or biogenic, derived from siliceous phytoplankton (diatoms, silicoflagellates), protozoans and protists (radiolarians and ebridians), plant phytoliths, some scolecodonts (polychaete worm jaws) and sponge spicules. Normalisation using a detrital divisor can distinguish terrigenous or productivity origin

Use

Like Fe and Ti, Si used as a proxy for terrigenous sediment delivery (Blanchet et al. 2007; Kleiven et al. 2007) or in provenance studies, e.g. turbidite sources (Frenz et al. 2009). Si profile shape may give information on textural character of coarse-grained turbidites, e.g. distinguish massive and graded sands (Rothwell et al. 2006) Applications and literature • Variation in terrigenous sediment delivery Blanchet et al. (2007); Kleiven et al. (2007) • Textural character Rothwell et al. (2006) • Provenance studies Frenz et al. (2009)

Si/Ti

Use

Si/Ti used as a proxy for siliceous productivity (Agnihotri et al. 2008; Marsh et al. 2007)

Applications and literature

• Siliceous productivity Agnihotri et al. (2008); Marsh et al. (2007)

Si/Ca

Use

Si as a representative terrigenous element has been ratioed with Ca to record aeolian dust supply (Hanebuth and Henrich 2009)

Applications and literature

• Aeolian dust flux/wind strength Hanebuth and Henrich (2009)

Si/Sr

Use

Si/Sr used to identify layers poor in biogenic carbonate and relatively rich in detrital silicates (quartz, feldspar etc.), such as ice-rafted debris layers (Hodell et al. 2008). In this study, Si/Sr peaks correlated with lows in bulk carbonate ∂18O, probably representing lower biogenic carbonate productivity and/or increased delivery of IRD rich in silicate minerals

Applications and literature

• Detection of ice-rafted-debris • Oceanic productivity Hodell et al. (2008)

Si/Al

Use

Si/Al used as proxy for wind strength (Itambi et al. 2009; Revel et al. 2010) with high values indicating high aeolian flux, and as a proxy for biogenic production (Dickson et al. 2010). In one study used to infer weathering intensity (Sluijs et al. 2008). Si/Al considered a proxy for changes in aluminosilicate composition by Tisserand et al. (2009)

Applications and literature

• Aeolian dust flux/wind strength Itambi et al. (2009); Revel et al. (2010) • Oceanic productivity Dickson et al. (2010) • Weathering intensity Sluijs et al. (2008) • Aluminosilicate composition Tisserand et al. (2009)

Titanium (Ti)

Origin

Ti is conservative element that generally varies directly with the coarse-grained terrigenous fraction. A common constituent of rocks, such as gneisses or schists, it primarily indicates a terrigenous continental source. Ti predominatly occurs as the sortable heavy mineral rutile (TiO2). Other sources are anatase (TiO2), brookite (TiO2), ilmenite (FeTiO3) sphene (CaTiSiO5) and titanomagnetite (Fe2+(Fe3+Ti)2O4), all minerals commonly associated with sand and silt fractions. Ti may increase with biotite enrichment. It is enriched in tropical soils such as laterites and bauxites. Ti not affected by diagenetic overprinting or involved in biological processes and therefore represents allochthonous minerogenic input

Use

Ti is widely used to record terrigenous sediment delivery, particularly through runoff, and hence assess hinterland climate, particularly rainfall (e.g. Haug et al. 2001, 2003; Kissel et al. 2010; Peterson et al. 2000 and others). It commonly co-varies with Fe, but is arguably a better proxy for terrigenous sediment delivery than Fe as it is redox-insensitive (Calvert and Pedersen 2007; Yarincik et al. 2000). In any case, use of Fe as run-off proxy should be checked against Ti (e.g. Haug et al. 2001). Ti has also been widely used as a proxy for aeolian dust input (e.g. Xu et al. 2008), particularly throughout the Mediterranean/Middle East region (e.g. Ivanochko et al. 2005; Wehausen and Brumsack 2000) Ti spikes may correlate with turbidites or ash layers (e.g. Westerhold et al. 2009). Turbidites commonly have coarser-grained bases, and if silty or sandy, typically show abrupt increases in element concentrations resulting in asymmetric Ti distributions. In contrast, tephra layers tend to show more symmetrical Ti peaks (Sluijs et al. 2008) Ti has also been used to identify major sedimentary breaks and climatic precession and obliquity variations in IODP cores to produce a coherent age model (Backman et al. 2008) and recording sea-ice melting with release of terrigenous particles (Jaccard et al. 2009; Solignac et al. 2011) Loess may concentrate heavy minerals, so be enriched in high field-strength elements like Ti (Itambi et al. 2010). Ti, like Fe, is commonly carried by wind as a clay coating/embedding coarse dust grains, as seen off NW Africa, where alluvial terraces with extensive ferruginous lateritic soils provide a Ti source (Nizou et al. 2011) Limitations: Overall increase in Ti with depth has been attributed to compaction (e.g. Cheshire et al. 2005) and like other elements, values may decrease towards core tops, due to lower compaction and dilution by higher water content. Ti also likely to vary with grain size, as it is typically concentrated in coarser grain-sizes

Applications and literature

• Variation in terrigenous sediment delivery • Precipitation and runoff • Hinterland climate Carlson et al. (2008); Cheshire et al. (2005); Chiessi et al. (2009); Denis et al. (2006); Haug et al. (2001, 2003); Kissel et al. (2010); Marsh et al. (2007); Peterson et al. (2000); Teodoru et al. (2007) • Aeolian dust flux/wind strength Ivanochko et al. (2005); Wehausen and Brumsack (2000); Xu et al. (2008) • Turbidites and ash layers Sluijs et al. (2008); Westerhold et al. (2009) • Production of coherent age models • Recording ice melting Backman et al. (2008); Jaccard et al. (2009); Solignac et al. (2011)

Ti/Ca

Use

Ti/Ca records relative variation of terrigenous input and marine carbonate (e.g. Bahr et al. 2005, 2008; Hoang et al. 2010). It has been used to record changes from fluvial to marine deposits, for example, in incised-valley-fill sediments (Tjallingii et al. 2010). It has also been used as a proxy for dust supply (e.g. Henrich et al. 2010; Pierau et al. 2011; Romero et al. 2008) allowing assessment of continental aridity and relative wind strength. Ti/Ca also used to identify detrital-rich sands (high Ti) and foraminifer-rich turbidites (high Ca) (e.g. Bourget et al. 2008) and in varve counting and recording influx of IRD released by deglacial meltwater discharges (recorded as Ti/Ca spikes) (Soulet et al. 2011). Ti/Ca has also contributed to construction of regional chronologies (e.g. for the Black Sea, a sensitive recorder of past climate change) by tuning to climate reference records (Soulet et al. 2011)

Applications and literature

• Variation in terrigenous sediment delivery • Identification of freshwater/marine transitions Bahr et al. (2005, 2008); Hoang et al. (2010); Tjallingii et al. (2010) • Aeolian dust flux/wind strength • Hinterland climate • Precipitation and runoff • Sediment transport Romero et al. (2008); Henrich et al. (2010); Pierau et al. (2011); Jaeschke et al. (2007) • Core characterisation • Varve counting • Recording ice melting • Constructing chronology Bourget et al. (2008); Soulet et al. (2011)

Ti/Al

Use

Ti/Al used as proxy for aeolian dust flux/wind strength, hence hinterland aridity (Itambi et al. 2009; Jullien et al. 2007; Tisserand et al. 2009). Jiménez-Espejo et al. (2007a) used average concentration of Ti in Pleistocene cores from ODP Site 975 (Balearic Abyssal Plain, W Mediterranean Sea) to normalize Ti to Al. This normalized average, called Timean/Al, related to aeolian terrigenous input to Balearic Basin, which, together with other data, provided information on Iberian hinterland climate during time of Neanderthal extinction around 25–30 ka. Higher Ti/Al values have been related to greater coarse-grained lithogenic flux, often climatically modulated (e.g. Ziegler et al. 2009). More intense weathering has also been inferred from low Ti/Al values (Sluijs et al. 2008)

Applications and literature

• Aeolian dust flux/wind strength • Hinterland climate • Precipitation and runoff Itambi et al. (2009); Jiménez-Espejo et al. (2007a); Jullien et al. (2007); Tisserand et al. (2009) • Variation in terrigenous sediment delivery • Climatic variability • Weathering intensity Sluijs et al. (2008); Ziegler et al. (2009)

Ti/K

Use

Ti/K mainly used to infer variations in sediment source (Siani et al. 2010; Spofforth et al. 2008) and identify ice-rafted-debris (Prins et al. 2001). Ti/K also used for core correlation by Brendryen et al. (2010). In Nordic Seas, Ti/K shows a correlation with magnetic susceptibility and the Greenland NGRIP ∂18O temperature record (Brendryen et al. 2010; Richter et al. 2006), probably due to erosion and transport of magnetic and Ti-rich minerals from basaltic Iceland-Scotland Ridge by bottom currents dependant on inflow of Atlantic water to Nordic Seas

Applications and literature

• Sediment provenance Siani et al. (2010); Spofforth et al. (2008) • Detection of ice-rafted-debris Prins et al. (2001) • Core correlation • Sediment transport • Current and water mass changes Brendryen et al. (2010)

Ti/Fe

Use

Ti/Fe used as proxy for wind strength/hinterland aridity (Zarriess and Mackensen 2010). As an element of heavy minerals (e.g. rutile), Ti is transported dominantly in Saharan dust, so its concentration reflects wind intensity off NW Africa (Schütz and Rahn 1982). Ti/Fe also used as a provenance indicator to discriminate material from local volcanic sources (Konfirst et al. 2011)

Applications and literature

• Aeolian dust flux/wind strength • Hinterland climate Zarriess and Mackensen (2010) • Sediment provenance Konfirst et al. (2011)

Ti/Rb

Use

Ti/Rb used to show enhanced heavy resistate minerals in turbidite bases (Rothwell et al. 2006)

Applications and literature

• Presence of heavy minerals Rothwell et al. (2006)

Ti/Sr

Use

Ti/Sr used to measure terrigenous versus biogenic sediment contribution and climatic modulation of supply (Zaragosi et al. 2006)

Applications and literature

• Variation in terrigenous sediment delivery • Climate variability Zaragosi et al. (2006)

K/Ti

Use

K/Ti used as proxy for authigenesis in cores from summits of carbonate mounds in Rockall Trough, NE Atlantic (Land et al. 2011). A zone of Fe and Mn enrichments showed low κ/Ti and high Fe/κ, interpreted as resulting from dissolution of magnetic minerals

Applications and literature

• Iron and manganese diagenesis • Authigenesis Land et al. (2011)

Zirconium (Zr)

Origin

Zr mainly occurs in zircon (ZrSiO4), a dense resistant mineral, ubiquitous in the crust and occurring in igneous rocks as primary crystallisation products and in sediments as detrital grains. Zircons tend to maintain their original morphology during weathering and transport, and are usually enriched in coarse sediment fractions

Use

Zr may be high in ash layers. Ash layers with low Ti and high Zr composition point to an alkaline magma type (Westerhold et al. 2009)

Applications and literature

• Identification of tephras Westerhold et al. (2009)

Zr/Ti

Use

Marsh et al. (2007) found Zr/Ti in cores around Crozet Plateau, S Indian Ocean, was provenance sensitive with high values indicating input of volcanic material from Crozet Island via sediment gravity flows

Applications and literature

• Sediment provenance Marsh et al. (2007)

Zr/Rb

Use

Zr/Rb provides a grain-size proxy as Zr resides mainly in coarser grains and Rb in clays. Has been used to reconstruct river flood histories, as floods carry greater coarse-grain sediment loads, hence Zr/Rb increases in flood events (e.g. Wang et al. 2011). The higher the Zr/Rb peaks, the greater number of coarse particles deposited by saltation processes. Zr/Rb has also been used as a winter monsoon proxy (Liu et al. 2002)

Applications and literature

• Precipitation and runoff Liu et al. (2002); Wang et al. (2011)

Zr/Sr

Use

Hodell et al. (2010) used Zr/Sr as IRD proxy in core from Garder Drift, Reykjanes Ridge, N Atlantic

Applications and literature

• Detection of ice-rafted-debris Hodell et al. (2010)

Zr/Fe

Use

Zr/Fe used to discriminate sediment supply from local volcanic sources (Konfirst et al. 2011)

Applications and literature

• Sediment provenance Konfirst et al. (2011)

Manganese (Mn)

Origin

Mn makes up ~1000 ppm of the Earth’s crust, making it the 12th most abundant crustal element (Emsley 2001). Mn-bearing minerals not uncommon, occurring as oxides, silicates and carbonates, with pyrolusite (MnO2) and rhodochrosite (MnCO3) the most common. Most Mn in deep-sea sediments (~70–80%) has a hydrothermal origin and Mn-bearing minerals undergo substantial alteration during early diagenesis. Mn-rich crusts commonly cover rocky outcrops and Mn polymetallic nodules cover substantial areas of seafloor. Microscopic Mn

Use

Highly redox-sensitive, Mn has been used in wide range of diagenetic and process studies. Covariance with other redox-sensitive or detrital elements may indicate potential Mn sources. Pervasive Mn enrichment occurs in central Arctic Ocean sediments during interglacials and interstadials (Löwemark et al. 2008; O’Regan et al. 2010). This is attributed to enhanced Mn flux to central Arctic during deglacial or interglacial periods, or from sluggish intermediate and deep-water circulation during glacials (Jakobsson et al. 2000). In the latter case, stagnant bottom and intermediate waters lead to dysoxia with Mn only precipitating during ventilated interglacial/interstadial periods. Downhole Mn was not strongly correlated with other redox-sensitive elements, suggesting it may record primary depositional signal (Löwemark et al. 2008). Mn enrichment in interglacials may reflect enhanced Mn flux from circum- Arctic rivers, or flooding of shelves, but the exact mechanism is unresolved. Arz et al. (2006) used Mn and other parameters to characterise pronounced dry event, dated 4.2 ka, recorded in sediments of Shaban Deep (Red Sea), previously linked to collapse of the Akkadian empire (Weiss et al. 1993)

Applications and literature

• Diagenesis • Climate variability Arz et al. (2006); Löwemark et al. (2008); O’Regan et al. (2010)

Mn/Fe

Use

Mn/Fe used to assess redox conditions as Mn is mobile under sub-oxic conditions and separates from Fe during diagenesis (Marsh et al. 2007). Constant Mn/Fe ratios indicate oxic conditions and no element fractionation. Mn/Fe peaks occur during suboxic diagenesis when Mn is mobilised and diffuses along concentration gradients to precipitate at new oxic/post-oxic boundary. Non-steady state diagenesis such as oxic burn-down through turbidites leads to Mn/ Fe peak formation (Thomson et al. 1993)

Applications and literature

• Diagenesis • Redox conditions Marsh et al. (2007)

Mn/Ti

Use

Mn/Ti used to document diagenetic relocations and Mn enrichment (e.g. Land et al. 2011). Mn/Ti (and Fe/κ) used by Hepp et al. (2009) to document late Miocene-early Pliocene Antarctic deepwater record of repeated Fe reduction events, resulting in significant losses of magnetic susceptibility signal at ODP Site 1095 (Pacific continental rise, W Antarctic Peninsula). Mn/Ti also used to determine extent of post-depositional oxidation of Eastern Mediterranean sapropels (Thomson et al. 2006)

Applications and literature

• Diagenesis Hepp et al. (2009); Land et al. (2011); Thomson et al. (2006)

Mn/Al

Use

Mn/Al interpreted as recording changes in oxygenation with high Mn/Al suggesting periodic oxygenation (Spofforth et al. 2008). Jaccard et al. (2009) used Mn/Al to map modern redoxcline and redox transitions in Quaternary cores from ODP Site 882 (subarctic NW Pacific)

Applications and literature

• Diagenesis Jaccard et al. (2009); Spofforth et al. (2008)

Potassium (K)

Origin

K generally associated with terrestrial siliciclastics, e.g. illite clays (potassium mica) and potassium feldspar (microcline, orthoclase, sanidine). Illite is K's main mineralogical carrier and in fine-grained sediments, high K suggests a high illitic component Limitations: The K peak in the XRF intensity spectrum is attached to Ca peak, so is easily tampered by varying Ca signal. Normalisation of K in counts per second to total counts in order to receive independent K signal improves correlation (Kujau et al. 2010) Use: An important terrigenous indicator, K has been used as a proxy for fluvial input allowing inferences on hinterland humidity/aridity and climatic modulation (e.g. Holzwarth et al. 2010; Kuhlmann et al. 2004b; Romero et al. 2008)

Applications and literature

• Variation in terrigenous sediment delivery • Precipitation and runoff • Hinterland climate Holzwarth et al. (2010); Kuhlmann et al. (2004b); Romero et al. (2008)

K/Ti

Use

K/Ti has been used to emphasize provenance differences of detrital material (Diekmann et al. 2008; Richter et al. 2006), with the proxy being useful with sediment supplied largely by weathering of schists and slates. Diekmann, et al. (2008) found K/Ti variations recorded provenance changes in Okinawa Trough sediments, off NE Taiwan. Ti is enriched above the mean of upper continental crust in the particulate load of Yangtze River, draining E China lowlands. Thus low K/Ti suggested sediment supply from E China, while high K/Ti marked influx of illite-rich material from Taiwan. K/Ti used by Hodell et al. (2010) to assess relative contribution of felsic and mafic sources of terrigenous sediments in a core from Garder Drift (Reykjanes Ridge, N Atlantic). These source changes reflected varying strength of Iceland- Scotland Overflow Water (ISOW) over time. These data showed ISOW was stronger during long warm interstadial periods. K/Ti has also been used as a proxy for weathering intensity and erosion with values related to sediment source and transport processes (Piva et al. 2008). At the PRADI-2 deep borehole on the Adriatic continental slope, K was mainly concentrated in K-feldspar and illite, while Ti was largely present in rutile and concentrated in the coarse fraction, probably predominantly brought in by aeolian dust. Both K/Ti and Ca/Ti allowed recognition of Dansgaard-Oeschger events in the Adriatic (Piva et al. 2008). Richter et al. (2006) used K/Ti to show Dansgaard-Oeschger cycles in Faeroe margin sediments accompanied by repetitive shifts in composition of terrigenous fraction. K and Ti were linked to acidic and basaltic sources respectively

Applications and literature

• Sediment provenance Diekmann et al. (2008) • Current and water mass changes Hodell et al. (2010) • Weathering intensity • Climatic variability • Sediment provenance Piva et al. (2008); Richter et al. (2006)

K/Ca

Use

K/Ca used by McGregor et al. (2009) in cores from offshore S Morocco to demonstrate dramatic increase in terrigeneous sedimentation rate coincident with arrival of Islam around 650-850 A.D., probably related to population increase, expanded pastoralism, deforestation and agriculture

Applications and literature

• Variation in terrigenous sediment delivery • Anthropogenic changes McGregor et al. (2009)

K/Rb

Use

Rothwell et al. (2006) record K/Rb enhanced in turbidite muds, presumably due to high illite. However, Croudace et al. (2006) regards K/Rb as potentially unreliable parameter as seawater Cl absorbs K X-rays, hence high K may reflect increased porosity

Applications and literature

• Clay content Rothwell et al. (2006)

K/Al

Use

K/Al used as a measure of mobile versus immobile elements by Clift et al. (2008) in a study investigating Monsoon inception. Most precipitation in India and China caused by seasonal storms of S and E Asian monsoons, which thus control runoff. K/Al and other weathering proxies revealed Monsoon activity history. K/Al also used a proxy for illite variation, and hence variation in hinterland rainfall where illite is abundant in continental soils, e.g. South Africa (Dickson et al. 2010)

Applications and literature

• Precipitation and runoff • Weathering intensity Clift et al. (2008); Dickson et al. (2010)

Zinc (Zn)

Origin

Zn has low abundance in marine environment with concentrations typically < 150 ppm in argillaceous sediments. Zn enrichment, particularly in coastal sediments, normally points to anthropogenic sources, or extremely high terrigenous supply. Marginal environments such as fjords and lagoons near industrial areas may contain significant Zn due to high accumulation rates and tendency to act as natural sediment traps, providing potential for high-resolution anthropogenic impact studies

Use

Zn has been used to record anthropogenic pollution and identify different sediment sources (Hebbeln et al. 2003). Cage and Austin (2010) used Zn to test a decadal-scale reconstruction of UK coastal temperature anomalies over last millennium based on long core from Loch Sunart, NW Scotland. A rapid increase in Zn occurred post 1860 A.D., agreeing with reported increase in anthropogenic zinc attributed to atmospheric deposition from around 1850 A.D. in Scottish lake sediments from early industrial sources (e.g. Kreiser et al. 1990)

Applications and literature

• Anthropogenic pollution • Sediment provenance Hebbeln et al. (2003) • Chronology construction Cage and Austin (2010)

Barium (Ba)

Origin

Ba is important proxy for export paleoproductivity and may be useful for core-to-core correlation where Ba signal-to-noise ratio is high. Its relationship to productivity is wellestablished. Relatively high concentrations of tiny Ba-rich particles (< 2 μm in diameter) occur in near-surface waters (Dehairs et al. 1980 and others) especially in areas of high productivity (Dehairs et al. 1992; Cardinal et al. 2005). This Ba is commonly associated with biogenic aggregates, particularly siliceous debris (Bishop 1988) and constitutes most of the suspended Ba in water column. Particulate Ba occurs within skeletal and organic detritus, most likely precipitating in microenvironments containing concentrated dissolved Ba or sulphate, such as decaying organic matter (Chow and Goldberg 1960; Dehairs et al. 1980; Calvert and Pedersen 2007). Although Ba crystals form intracellularly in some marine protists, e.g. xenophyophores (Gooday and Nott 1982; Rieder et al. 1982), determination of a widespread Ba-secreting planktonic organism has proved elusive. There is evidence for tiny barite crystals forming during phytoplankton decay (Ganeshram et al. 1992, 2003). The insoluble nature of barite means a high degree of preservation in slowly-accumulating oxic sediments Ba may have a lithogenic origin, occuring in K-feldspars and micas, where it substitutes isomorphically for K (Puchelt 1969–1978). Although compared to biogenic Ba this contribution is usually small. Normalization with Al commonly used to assess detrital Ba component, combined with estimates of Ba/Al ratio of average crustal rocks or of the aluminosilicate fraction in a specific sediment sample (Calvert and Pedersen 2007) Limitations: Ba records may be compromised by post-depositional loss in suboxic (McManus et al. 1998; and others) and especially anoxic sediments affected by sulphate depletion (Os et al. 1991; Brumsack and Gieskes 1983; and others). Thus Ba records from many continental margins, where relatively high Corg results in lower redox potentials at shallow depth, do not normally reflect productivity (Shimmield et al. 1994; Ganeshram et al. 1999). Sulphate reduction in microenvironments may result in Ba dissolution, even in oxic and suboxic settings, hence assessment of productivity needs multi-proxy approach, including measurement of Corg and biogenic opal Use: Ba has been effectively used as productivity proxy (e.g. Jaccard et al. 2009; Ziegler et al. 2009) and for core-to-core correlation (e.g. Röhl et al. 2007; Kelly et al. 2010). Westerhold et al. (2009) showed Ba intensity during Palaeocene-Eocene sequence at ODP Site 500 (Goban Spur, NE Atlantic) showed extremely well-developed cycles, related to precession cyclicity. Changes in Ba and barite fluxes during the Palaeocene-Eocene Thermal Maximum, if global, must largely be consequence of changes in Ba supply, either from rivers or methane hydrates, rather than due to productivity alone (Dickens et al. 2003). Some Ba is likely recycled during early diagenesis: adsorbed on mineral surfaces, co-precipitated with Fe-Mn oxyhydroxides or precipitated as barite (Paytan and Kastner 1996). In a novel application, Breier et al. (2010) used Ba in cores from semi-arid bays along south Texas coast to study dissolved radium isotopes, probably derived from relic sedimentary barite from discontinued practice of oil-field brine discharge

Applications and literature

• Export productivity Jaccard et al. (2009); Ziegler et al. (2009) • Core correlation Kelly et al. (2010); Röhl et al. (2007) • Climate variability • Diagenesis Dickens et al. (2003); Westerhold et al. (2009) • Radium isotopes Breier et al. (2010)

Ba/Ca

Use

Grove et al. (2010) used Ba/Ca and Sr/Ca as a proxy for aragonite in onshore massive corals on Madagascar, relating this to spectral luminescence resulting from incorporation of soil-derived humic acids transported to reef during major flood events. These data were used to derive a proxy for runoff and hence hinterland rainfall

Applications and literature

• Proxy for aragonite • Precipitation and runoff Grove et al. (2010)

Ba/Al

Use

Ba/Al used to determine export productivity, particularly in Pacific Ocean (e.g. Jaccard et al. 2005, 2010) and around Antarctica (Hillenbrand et al. 2009). Productivity often strongly modulated by climate. Jaccard et al. (2005) interpreted low biogenic Ba at glacial maxima at ODP Site 882 (N Pacific Ocean) as reflecting decreased nutrient supply, probably resulting from polar stratification during cold periods. Ba/Al used to construct age model for ODP Site 882 (E of Kamchatka, NW Pacific) (Galbraith et al. 2008)

Applications and literature

• Export productivity Hillenbrand et al. (2009); Jaccard et al. (2005, 2010) • Climate variability Jaccard et al. (2005) • Chronology construction Galbraith et al. (2008)

Ba/Ti

Use

Ba/Ti used as proxy for palaeoproductivity in sapropel-bearing cores from E Mediterranean (Thomson et al. 2006). Proxy especially useful in showing true sapropel thickness prior to bottom-water oxidation

Applications and literature

• Export productivity Thomson et al. (2006)

Copper (Cu)

Origin

Cu has low abundance in ocean sediments and little environmental significance. Elevated concentrations of hydrothermal origin recorded in crusts on the Mid Pacific Rise (Baturin et al. 1987) and Red Sea median valley sediments (Blossom 2006). Cu is redox-sensitive. Cu binds with organic matter, which generally occurs in greater amounts in freshwater sediments than in marine deposits, hence Cu typically has higher concentrations in freshwater sediments (Sparrenbom et al. 2006)

Cu/Rb

Use

Cu/Rb used to record diagenetic mobilisation of copper (Rothwell et al. 2006)

Applications and literature

• Diagenesis Rothwell et al. (2006)

Cu/Ti

Use

Thomson et al. (2006) found Cu/Ti a useful marker of post-depositional oxidation in sapropel-bearing cores from E Mediterranean

Applications and literature

• Diagenesis Thomson et al. (2006)

Arsenic (As)

Origin

As is strongly incorporated into pyrite, substituting for S (Peterson and Carpenter 1986; Huerta-Diaz and Morse 1992). As has low concentration in detrital minerals and is generally close to the limit of detection in absence of pyrite. Its relative environmental rarity compared to ubiquitous Fe and efficient excitation using Mo tube makes As an efficient proxy for pyrite ===Use===As used as proxy for pyrite authigenesis in sapropel-bearing cores from E Mediterranean by Thomson et al. (2006)

Applications and literature

• Pyrite authigenesis Thomson et al. (2006)

Sulphur (S)

Origin

S is closely linked to organic matter with S residing in biomass of marine plants and mineralised S in their dead remains. Within sediments organic S may be oxidised to sulphate and returned to seawater, or buried as organic S, sulphate or sulphide, through bacterial reduction (Ivanov 1981). S may be connected to a reduced iron sulphide phase, and bound in organic-rich laminated mud sequences (organic S) and hence serve as proxy for oxygen depletion in bottom water (Harff et al. 2011)

Use

High S contents, together with other suboxic indicators (e.g. increased pyritization, high Fe/S ratios, elevated trace element/Al ratios) indicate reducing conditions.For example, Sluijs et al. (2008) used S abundance in sediments from Upper Paleocene and Lower Early Eocene at IODP Site M0004 (Lomonosov Ridge, Arctic Ocean) to identify reducing suboxic conditions during Paleocene-Eocene Thermal Maximum

Applications and literature

• Redox conditions Sluijs et al. (2008)

S/Cl

Use

Thomson et al. (2006) used S/Cl in sapropel-bearing cores from E Mediterranean to detect enhanced S associated with pyrite or organic carbon (Passier et al. 1999) in excess of constant S/Cl sea-salt ratio

Applications and literature

• Pyrite authigenesis • High organic carbon Thomson et al. (2006) Rubidium (Rb)

Origin

Isomorphic Rb is a dispersed element in nature and widely distributed in rock-forming minerals, but seldom forms distinct mineral species. As Rb and K have similar particle radii, potential and other properties, Rb mainly occurs dispersed in minerals containing K, such as biotite, muscovite, feldspar and illite. During weathering, Rb is enriched in detrital clay minerals ===Use===In absence of precise Al data, Rb may be effective for normalisation (Rothwell et al. 2006)

Applications and literature

• Data normalisation Rothwell et al. (2006)

Bromine (Br)

Origin

Br does not occur naturally but occurs as bromide compounds in diffuse amounts in crustal rocks. Leaching results in seawater having a bromide salt content of 65 ppm (Tallmadge et al. 1964). Marine organisms in particular synthesize a variety of low molecular weight organic Br molecules (Dembitsky 2002; Gribble 2000; and others) and approximately 2000 natural Br compounds are known, the majority of marine origin (Gribble 2003). Hence, bromine is concentrated in organic matter, showing marked enrichment in organic-rich layers, such as sapropels

Use

Br is widely used to quantify marine organic matter and related productivity (e.g. Caley et al. 2011; Ren et al. 2009; Ziegler et al. 2008, 2009). Terrestrial organic matter is comparatively poor in Br, making it a good discriminant of marine and freshwater conditions (Malcolm and Price 1984; Mayer et al. 2007). For example, McHugh et al. (2008) took Br contents of

200 cts/s as indicating marine rather than freshwater-derived organic matter in cores from

Marmara Sea, Turkey. Such data taken together with other markers, such as foraminifer and molluscan faunal changes, were used to determine changes from marine to freshwater conditions during sea-level changes. The analysis allowed tracking of global sealevel as it breached the Bosphorus and Dardanelles sills

Applications and literature

• Marine organic matter • Productivity Caley et al. (2011); Ren et al. (2009); Ziegler et al. (2008, 2009) • Marine and freshwater conditions • Sealevel changes McHugh et al. (2008)

Br/Cl

Use

Thomson et al. (2006) used Br/Cl as proxy for increased organic matter and higher porosity in sapropel-bearing cores from E Mediterranean

Applications and literature

• Marine organic matter • Porosity changes Thomson et al. (2006)

Br/Ti

Use

Agnihotri et al. (2008) used Br/Ti as organic productivity indicator in core from Peru margin

Applications and literature

• Organic productivity Agnihotri et al. (2008)

xrf/start.txt · Dernière modification : 2018/03/02 17:43 de zaragosi