Application Of Stable Isotope Techniquesto Inorganic And Biogenic Carbonates

Ito, Emi

doi:10.1007/0-306-47670-3_13

Cited by 40 publications

(39 citation statements)

References 57 publications

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“…Several studies have addressed the usefulness and effectiveness of organic matter removal methods (Bellemo, 1976;Conger et al, 1977;Gaffey and Bronnimann, 1993;Ito, 2001). In addition, large uncertainties remain in regard to the effects of such methods on δ 13 C and δ 18 O values (Duplessy et al, 1970;Hodgkinson, 1991;Sarkar et al, 1990).…”

Section: Resultsmentioning

confidence: 99%

Effects of sample pre-treatment on the δ13C and δ18O values of living benthic foraminifera

Serrano

Mateo

2008

Chemical Geology

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Stable carbon and oxygen isotope ratios (δ 13 C and δ 18 O) of the epibenthic foraminiferan Elphidium macellum var. aculeatum were measured and compared both in raw aliquots and after various preanalytical treatments. We tested the effects of chemical cleaning procedures (oxygen plasma ashing, NaClO and H 2 O 2 ) and physical (ultrasounds) aimed at removing allochthonous particles.We also assessed the effects of using preservatives (formaldehyde and ethanol) and stains (Bengal Rose and Sudan Black B) prior to δ 13 C and δ 18 O analyses. Although the effects were generally small, three of the pre-treatments had a significant effect on δ 13 C or δ 18 O values. The use of Sudan Black B for vital identification caused a significant enrichment in the 13 C of the samples (0.24‰).In addition, sample oxidation with hydrogen peroxide and ultrasonic cleaning each led to a slight decrease in δ 18 O values (-0.18‰, in both cases). Our results demonstrate that Sudan Black B should be avoided prior to isotopic analysis. Bengal Rose showed no significant effect and should be used instead for staining. Because palaeoclimatic studies are based in small isotopic shifts, we discourage the pre-analysis use of unnecessary harsh cleaning treatments of foraminifera shell samples that may lead to isotopic fractionation and hence confound ecological interpretation.

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Section: Resultsmentioning

confidence: 99%

Effects of sample pre-treatment on the δ13C and δ18O values of living benthic foraminifera

Serrano

Mateo

2008

Chemical Geology

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“…In hydrologically open systems, however, a range of other factors, such as precipitation source region or temperature, may be more important (Leng and Marshall, 2004). The analysis of either bulk carbonate or of individual carbonate microfossils (in this case gastropods) can result in problems of interpretation (Ito, 2001). The calcite in bulk sediment samples may come from different sources, or reflect seasonal rather than annual average conditions.…”

Section: Methodsmentioning

confidence: 99%

Environmental change in northern Belize since the latest Pleistocene

Metcalfe

Breen

Murray

et al. 2009

J Quaternary Science

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Cores from the New River Lagoon in Belize have been analysed using a range of palaeolimnological proxies to reconstruct change since the latest Pleistocene. The combination of diatom and stable isotope analyses (supported by mineralogical and major element data) indicate that the New River Lagoon has been a freshwater system throughout the period of record. For most of this time the lagoon has been hydrologically open, but there are indications that it may have become closed in the latest Pleistocene or very early Holocene. This may have been associated with a drier climate and lower sea level. Mid-Holocene records are consistent with those from elsewhere in the region, indicating a stable and moist climate. The late Holocene was marked by greater variability, but there is no clear evidence of any drying in the late Classic coincident with the Maya 'collapse' ca. AD 900. Our results indicate that the continuity of occupation at the Maya site of Lamanai on the shores of the New River Lagoon is consistent with continued access to freshwater during periods of regional climatic variability. The importance of conditions at individual sites when considering both system response and human vulnerability to climate change is emphasised.

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“…Physicochemical changes in lake water cause biota modifications that are frequently associated with carbonate deposition. Moreover, lacustrine carbonates contain mineralogical and geochemical markers, such as the isotopic composition of carbon and oxygen, furnishing quantitative data for paleoclimatic and paleohydrological approaches (Li and Ku, 1997;Utrilla et al, 1998;Valero-Garcés et al, 1999a;Ito, 2001;Shapley et al, 2005). Carbonate δ…”

Section: Introductionmentioning

confidence: 99%

Carbonate and organic matter sedimentation and isotopic signatures in Lake Chungará, Chilean Altiplano, during the last 12.3kyr

Pueyo

Sáez

Giralt

et al. 2011

Palaeogeography, Palaeoclimatology, Palaeoecology

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Sediments in lakes in the Andean volcanic setting are often made up of diatomaceous ooze together with volcaniclastics and small amounts of carbonates. Despite their scarcity, carbonates along with organic matter provide significant paleoenvironmental information about lake systems. This study focuses on the carbonates in Lake Chungará, their morphologies, distribution and origin deduced from the isotopic markers. These markers reflected changes in the water and the biomass between the onset of the Holocene and around 9.6 cal kyr BP. These changes are marked by general increases in TOC, TN, and TN-δ 15 N AIR , and by fluctuating values of TOC-δ 13 C VPDB in its sediments and are probably related to major shifts in the lake surface/volume associated with rises in lake level. An increase in salinity around 10 cal kyr BP is thought to be linked to a short dry period, giving rise to the onset of carbonate production. The mid-Holocene arid period between 7.3 and 3.5 cal ka BP, with a maximum of aridity around 6.0 cal kyr BP, was deduced from δ 18 O VPDB values in the endogenic carbonates. These results match the reconstructions in Lake Titicaca based on benthic diatoms and paleoshore levels. Offshore sediments mainly consist of a diatomaceous ooze, laminated in the lower half (Unit 1), and bandedmassive with tephra layers in the upper half of the sequence (Unit 2). TOC-δ 13 C VPDB and the C/N ratio confirm that phytoplankton was the main source of organic matter in these sediments. Shallower sediments (units 3 to 5) developed in platform and littoral settings, providing evidence of subaqueous macrophytes and, to a lesser extent, land plants. Carbonate content ranges between 0.1 and 6 wt.% in offshore settings (30 to 40 m water depth) and reaches the maximum values in the lower part of Unit 2. Carbonate minerals (low magnesium calcite and minor amounts of high magnesium calcite and aragonite) are scarce and are arranged in mm-thick layers, commonly forming cm-thick levels or bioclasts. Carbonate layers are made up of euhedral-to-subhedral spindle-shaped calcite crystals and, to a lesser extent, aragonite needles, all in the μm range. Aragonite spheroids coexist in littoral sediments with other carbonate shapes and charophyte remains, where carbonate reaches locally up to 20 wt.%. CO 2 photosynthetic depletions related to seasonal phytoplankton blooms were responsible for the high frequency deposition of mm-thick carbonate layers.The average values for δ 13 C VPDB in lake water, plankton and sediments of Lake Chungará (as organic matter or as carbonate) are around 15‰ higher than commonly reported values in other lakes. This 13 C enrichment is attributed to carbon assimilation from a DIC affected by methanogenesis, in which HCO 3 − is the dominant species. The δ 13 C VPDB and δ 18O VPDB variations and their covariation in endogenic carbonates suggest that lake water volume and lake level increased along the Holocene.

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Application Of Stable Isotope Techniquesto Inorganic And Biogenic Carbonates

Cited by 40 publications

References 57 publications

Effects of sample pre-treatment on the δ13C and δ18O values of living benthic foraminifera

Effects of sample pre-treatment on the δ13C and δ18O values of living benthic foraminifera

Environmental change in northern Belize since the latest Pleistocene

Carbonate and organic matter sedimentation and isotopic signatures in Lake Chungará, Chilean Altiplano, during the last 12.3kyr

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