Variation of the distribution coefficients of rare earth elements in modern coral-lattices: species and site dependencies

Akagi, Tetsuya; Hashimoto, Yohey; Fu, FengFu; Tsuno, Hiroshi; Tao, Hiroaki; Nakano, Yoshikatsu

doi:10.1016/j.gca.2003.12.014

Cited by 74 publications

(56 citation statements)

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“…The second possibility seems to be more acceptable than the first. Modern coral has the same REE/Ca ratio as seawater (Sholkovitz and Shen, 1995;Akagi et al, 2004;Wyndham et al, 2004), whereas REE/ Ca ratios of seamount-type limestones are 10 2 -10 4 times higher (Tanaka et al, 2003;Miura et al, 2004). Hence, seawater REEs were incorporated into the limestones when the original biogenic carbonate was recrystallized to inorganic calcite through dissolution and reprecipitation during early diagenesis and secondary growths of calcite occurred in contact with sufficient seawater (Tanaka et al, 2003).…”

Section: Incorporation Of Seawater Rees Into Seamount-type Limestonementioning

confidence: 99%

REE abundances in ancient seawater inferred from marine limestone and experimental REE partition coefficients between calcite and aqueous solution

Tanaka

Kawabe

2006

Geochem. J.

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In our earlier work, we determined relative REE partition coefficients between calcite and aqueous (CaCl 2 + NaCl) solution, but absolute values could not be obtained because of small overgrowths of calcite. In this study, we have made similar experiments in order to determine the absolute REE partition coefficients between calcite and aqueous solution, and have evaluated partition coefficients between calcite and seawater. Calcite-supersaturated solution doped with REEs was constantly pumped into a reactor to form calcite overgrowths on the seeds under CO 2 + N 2 gas. Absolute values of REE partition coefficients,show convex tetrad effects and Y/Ho fractionation, which is consistent with our earlier work. We have calculated REE abundances in Permian seawater using the partition coefficients corrected to seawater compositions and REE analyses of Permian seamount-type limestones. All the estimated REE abundances in Permian seawater indicate concave tetrad effects, large Y/Ho fractionation and negative Ce and Eu anomalies in their chondrite-normalized patterns, which are quite similar to those for present-day seawater. The estimated REE abundances in Permian seawater, however, are lower than those in present-day seawater by approximately one order of magnitude. This suggests that significant parts of marine limestones could not incorporate seawater REEs after the permeability and porosity of the original biogenic carbonate sediments with low-REE contents had been reduced to certain critical levels.Keywords: rare earth element, partition coefficient, carbonate complex, marine limestone, tetrad effect experiments between calcite and CaCl 2 -NaCl solution. Relative partition coefficients were determined successfully, but absolute values could not be obtained because of a difficulty in evaluating the amount of calcite overgrowths. In this study, we have conducted new series of experimental runs using the same experimental system as in our earlier work, and have acquired quantitative estimates of the amount of calcite overgrowths.The purposes of this study are, (i) to determine the absolute values of REE partition coefficients between calcite and aqueous solution, (ii) to estimate REE abundances in ancient seawater from a combination of the partition coefficients and REE data of limestone samples, and (iii) to discuss the early diagenetic process of marine carbonate in terms of the incorporation of seawater REEs into marine limestones.

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Section: Incorporation Of Seawater Rees Into Seamount-type Limestonementioning

confidence: 99%

REE abundances in ancient seawater inferred from marine limestone and experimental REE partition coefficients between calcite and aqueous solution

Tanaka

Kawabe

2006

Geochem. J.

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“…Most recently, the incorporation of lanthanides (Ln) into aragonite have generated growing interests. Many researchers have proposed coral Ln/Ca ratios as proxies for seawater chemistry [1][2][3][4] . They interpreted that lanthanides can not be enriched in aragonite.…”

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Enrichment of lanthanides in aragonite

Lü

Liu

2009

Journal of Rare Earths

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“…distribution coefficients; DREE) is an important consideration prior to their use in interpreting ambient seawater conditions , Webb and Kamber, 2000, Akagi et al, 2004 The variability in apparent DREE in core FRI 12.1 mainly affects the degree of LREE depletion, suggesting that this site is more influenced by LREE-rich runoff. High variability in LREEs has also been observed in Porites corals obtained from coastal Japan (Akagi et al, 2004) and the Indian Ocean, with the latter attributed to monsoon driven increases in terrestrially derived LREEs . Comparatively, HI 12.1 showed the most variability in the HREE, suggesting dissolved phase processes are dominant at this site.…”

Section: Apparent Distribution Coefficientsmentioning

confidence: 99%

“…To date, the behaviour of rare earth elements (REEs) and REE and Yttrium (REY) at sub-annual scales is relatively unknown, with few high resolution studies of REEs conducted on corals , Akagi et al, 2004, and only two records from the GBR . In…”

Section: Coral Luminescence and Ensomentioning

confidence: 99%

“…The rare earth elements (REEs) offer potential as a proxy for reconstructing rainfall/flood events and turbidity as, in coastal waters, ~90% are derived from suspended and dissolved riverine input (Dubinin, 2004). Yet, compared with Ba and Y, high resolution records of REEs in corals are relatively few , Akagi et al, 2004, and only two records of REEs in corals from the GBR are currently available .…”

Section: Introductionmentioning

confidence: 99%

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Holocene sea level and climate variability on the Great Barrier Reef, Australia

Leonard¹

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The Great Barrier Reef (GBR) is a natural, social and economic asset synonymous with Australia; however, there are concerns regarding both the frequency and extent of modern reef decline, especially in regions within close proximity to the coastline. With the future of coral reefs uncertain, elucidating the controls on reef growth and decline in the recent geological past prior to anthropogenic impacts is imperative to future management strategies. Numerous reef cores have revealed a substantial hiatus period or reef "turn-off" event during the mid-Holocene (~4600 years before present; yBP 1950) clearly prior to anthropogenic influence. Previously published research has suggested that changes in sea level, climate, and/or environmental conditions caused this reef "turn-off", but the exact cause is still tentative.Whether sea level varied significantly during the Holocene has been debated for over half a century, with oscillations generally dismissed as dating artefacts due to large age errors or to the misinterpretation or inaccuracies of the sea level indicator. Coral microatolls, one of the most reliable sea level indicators, were used to test whether relative (RSL) oscillations could be detected during the Holocene. Elevation surveys of sub-fossil coral microatolls (n=32) and non-microatoll reef flat corals (n=10) were conducted on three separate sites in the Keppel Islands, southern GBR and dated using high precision uranium thorium (U-Th) techniques. The resultant palaeo-sea-level reconstruction revealed a rapid lowering of RSL of at least 0.4 m from 5500 to 5300 yBP following a RSL highstand of ~0.75 m above present from ~6500 to 5500 yBP. RSL then returned to higher levels before a 2000-yr hiatus in reef flat corals after 4600 yBP.To determine if this was a local scale response, or part of a broader regional signal, the same methodology was applied to another 8 sites from a wide latitudinal range along the GBR (11˚S to 20˚S). The 94 U-Th dates of sub-fossil microatolls from this research adds support to the RSL lowering event at 5500 yBP, with microatolls close to present sea level found at ~5100 yBP. A second oscillation of ~ -0.3m at 4600 yBP was also detected in the northern GBR, with microatolls at three sites close to modern SL between 4600 -4000 yBP. The RSL oscillations at 5500 yBP and 4600 yBP coincide with both substantial reduction in reef accretion and wide spread reef "turn-off", respectively, thereby suggesting that oscillating sea level was the primary driver of reef shut down on the GBR.Understanding the coeval palaeo-climate and -environmental conditions may reveal both the cause of these sea level oscillations and further modes of stress placed on coral reefs prior to the midHolocene hiatus. In the first instance one of the simplest and most efficient methods of extracting information from the annual bands of massive Porites sp. coral cores is by using the growth characteristics (i.e. linear extension) and ultra violet (UV) luminescent intensity which are linked to II sea surface ...

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Variation of the distribution coefficients of rare earth elements in modern coral-lattices: species and site dependencies

Cited by 74 publications

References 32 publications

REE abundances in ancient seawater inferred from marine limestone and experimental REE partition coefficients between calcite and aqueous solution

REE abundances in ancient seawater inferred from marine limestone and experimental REE partition coefficients between calcite and aqueous solution

Enrichment of lanthanides in aragonite

Holocene sea level and climate variability on the Great Barrier Reef, Australia

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