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Showing 1 to 20 of 102 for “"Mg/Ca"”.
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Interpreting environmental change using bivalve shell geochemistry
… understanding of Earth’s climate beyond historical records, a number of paleoclimate proxies are used to infer how climate has changed throughout Earth’s history. Examined herein are two such geochemical proxies—the δ¹⁸O of the shell of the Australian mud or flat oyster, Ostrea angasi, and the …
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Interpreting environmental change using bivalve shell geochemistry
… understanding of Earth’s climate beyond historical records, a number of paleoclimate proxies are used to infer how climate has changed throughout Earth’s history. Examined herein are two such geochemical proxies—the δ¹⁸O of the shell of the Australian mud or flat oyster, Ostrea angasi, and the …
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Trace elements in marine biogenic carbonates: analysis and application to past ocean chemistry
Trace elements in marine biogenic carbonates may be used as proxies for past ocean<br/>chemistry provided that there is an established relationship between the trace element<br/>proxy and a parameter of interest, this relationship is preserved within biogenic<br/>carbonate, and the trace element …
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Establishing a Baseline for Kinetic and Thermodynamic Origins of Vital Effects: Toward an Understanding of Factors Controlling Mg Signatures in Calcite
… environmental conditions of formation. The Mg/Ca ratio in marine cements and calcified skeletal structures is a widely used proxy for reconstructing past earth environments. Many studies have positively correlated Mg content in biogenic carbonates with temperature, but it is difficult to …
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The centennial and millennial variability of the IndoPacific Warm Pool and the Indonesian Throughflow
… between the Pacific and Indian Oceans. The Mg/Ca and δ18O of calcite of Globigerinoides ruber (G. ruber) were used to estimate the sea surface temperature (SST) and δ18O of water, an indicator of hydrologic conditions, over the past 20,000 years. I also attempted to estimate thermocline …
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Records of Great Basin precipitation during MIS 11 from two Lehman Cave stalagmites
Trace elements (Mg/Ca and Sr/Ca) and stable isotopes ([delta]13C and [delta]18O) were measured in two coeval stalagmites, LC3 and BT1, from the Lehman Caves, Nevada. BT1 spans 388 to 384 ka. The LC3 record is split into two parts due to a hiatus observed through fluorescent imaging. The section …
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Environmental controls on the skeletal mineralogy of marine calcifiers
Calcifying organisms secrete skeletons consisting of calcium carbonate (CaCO3). The two principle CaCO3 polymorphs used by marine calcifiers are aragonite and calcite. In the abiotic precipitation of CaCO3, the Mg/Ca ratio and the temperature are established controls of polymorph formation, but the …
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The centennial and millennial variability of the IndoPacific warm pool and the Indonesian Throughflow
… relative difficulty of modeling the region. The Mg/Ca and [delta]¹⁸0 of calcite of the calcitic planktic foraminifera Globigerinoides ruber (G. ruber) were used to estimate the sea surface temperature and [delta]¹⁸0 of water, an indicator of hydrologic conditions, over the past 20,000 years. I …
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Abrupt climate change in the Atlantic Ocean during the last 20,000 years : insights from multi-element analysis of benthic and planktic foraminifera and a coupled OA-GCM
… perturbation? To address these questions, analytical methods were implemented for the simultaneous measurement of Mg/Ca, Zn/Ca, Cd/Ca, Mn/Ca and All Ca in foraminiferal samples using inductively-coupled plasma mass spectrometry. Paired records of planktic foraminiferal ()IRO and Mg/Ca from the …
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Using the growth patterns and geochemistry of coralline red algae to develop proxies for paleoclimate reconstruction in tropical and subarctic environments
… rhodoliths) of crustose coralline red algae (CCA) as geochemical proxy sources for paleoenvironmental and paleoclimate reconstructions. Rhodoliths (Lithothamnion sp.) from the Gulf of Panama (GOP), Panama were grown in a microcosm experiment to evaluate growth patterns and rates. Previous …
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The Use of the Ostracode Cyprideis Americana (Sharpe) as a Proxy for Salinity in Bahamian Lake Systems
… changes in salinity, and secrete low-magnesium calcite shells that preserve information about their host water chemistry. Changes in valve trace element concentration, stable isotope composition, and sieve pore shape values have been linked to changes in salinity. This study analyzed the …
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Abrupt climate change in the Atlantic Ocean during the last 20,000 years : insights from multi-element analysis of benthic and planktic foraminifera and coupled OA-GCM
… perturbation? To address these questions, analytical methods were implemented for the simultaneous measurement of Mg/Ca, Zn/Ca, Cd/Ca, Mn/Ca and Al/Ca in foraminiferal samples using inductively-coupled plasma mass spectrometry. Paired records of planktic foraminiferal [delta]¹⁸O and Mg/Ca from the …
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A one-year, postfire record of element deposition and cycling in the Kogelberg sandstone fynbos mountain ecosystem of the Western Cape, South Africa by Eugene W. Bergh.
Fire is a critical component of the fynbos ecosystem and this study documents the macronutrient (C1, Na, So4, Mg, Ca and K) dynamics of the fynbos for one year following a major fire event on 3 June 2010. Chloride and sodium in rainwater and stream water were found to be primarily derived from a …
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An examination of trace element concentrations across calcite/aragonite transitions in a Madagascan stalagmite
Calcite and aragonite speleothems have been used for the past few decades to provide paleoclimate information, but in speleothems of mixed mineralogy the signal of mineral changes can complicate understanding of climate signals also present. This mineral signal must therefore be examined and …
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Palaeoclimatology, stratigraphy and biotic responses in the middle Eocene
… global temperatures and higher atmospheric carbon dioxide (pCO2) levels than today with only<br/>small/non-existant icesheets. Because predicted pCO2 levels for the coming century have not been seen on Earth since at least ~40 Ma thus, the primary objective of this thesis is to improve our …
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Rhodoliths as environmental archives in the tropics
Rhodoliths are free-living forms of calcareous, coralline red algae that are found worldwide, from the tropics to the poles, in relatively shallow (0->250m) waters. They can live hundreds of years and continuously form a high-Mg calcite skeleton that presents periodical growth bands. Recent …
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Rhodoliths as environmental archives in the tropics
Rhodoliths are free-living forms of calcareous, coralline red algae that are found worldwide, from the tropics to the poles, in relatively shallow (0->250m) waters. They can live hundreds of years and continuously form a high-Mg calcite skeleton that presents periodical growth bands. Recent …
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Evolución paleoclimática durante el pleistoceno de la mitad sur de la Península Ibérica : mediante el estudio paleontológico y geoquímico de ostrácodos de la cuenca de Cúllar-Baza (Granada, España)
… lugar, se ha elaborado una síntesis geológica, estratigráfica y paleontológica de la cuenca de Guadix-Baza (Granada) general y de la cuenca de Cúllar-Baza (sector oriental de la cuenca de Guadix-Baza) en particular, en la que se ha reunido información de multitud de trabajos sobre la zona, …
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