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    Earth History

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Geosciences

The reading of Earth history satisfies a fundamental human urge to know how the world around us came to be. Throughout its 4.6 billion year history the Earth has undergone enormous transformation and stable isotope analysis has been at the forefront of developing our knowledge of these transformative processes. By understanding the macro and micro cycling mechanisms of the light stable isotopes through the lithosphere by natural processes the Earth history is continually being understood in ever more detail.

Paleoclimate

One of the earliest applications of light stable isotope mass spectrometry was the reconstruction of ancient climate based on the oxygen isotopic composition (δ18O) of preserved ancient marine carbonate, and continues to be one of the widely utilised methods for interrogating Earth’s climate history. This paleothermometer is based on the fundamental principle that the fractionation of oxygen isotopes into calcite is temperature dependent. The isoprime precisION with Dual Inlet and MultiCarb enables very precise and reliable automated measurement of carbonates, ideal for generating high-resolution paleo temperature records.

Cosmology

The sulfur isotope analysis of extra-terrestrial sulphide minerals, e.g. from meteorites, has provided a variety of insights into the origins of the Earth and the solar system. The isotopic composition of meteoritic sulfur (Canyon Diabolo triolite) was also used as a the original reference point for the bulk earth from which to evaluate global scale fractionations in the sulfur cycle. Sulfur-bearing minerals are easily analysed with our range of elemental analyser (EA-IRMS) systems, which utilise advanced purge and trap (APT) technology for unbeatable separation and peak focussing of SO2, ensuring perfect resolution and unparalleled sensitivity for mineral sulfur analysis. 

Stratigraphy

Fluctuations in δ13C through geological time are brought about by changes in the balance of fluxes of the carbon cycle.  Because the residence time in the carbon cycle is brief (10 ka), changes in flux are recorded accurately and globally in the sedimentary record. As such, occasional spikes in the global δ13C are useful as stratigraphic markers for chemostratigraphy, especially during the Paleozoic. The iso FLOW uses our novel UltiTrap technology to enable precise, high throughput continuous flow analysis of bulk carbonates to identify these isotope excursions.

Geoscientific publications using our instruments

Our customers use our instruments to do some amazing research in the geosciences. To show you how they perform their research and how they use our IRMS instruments, we have collected a range of peer-reviewed publications which cite our products. You can find the citations below and then follow the links to the publishing journal should you wish to download the publication.

If you would like to investigate our available citations in more detail, or email the citation list to yourself or your colleagues then take a look at our full citation database.

248 results:

Methane-derived authigenic carbonates from the uppermost Doushantuo Formation in South China: Was the Ediacaran Shuram Excursion a globally synchronized early diagenetic event?
Chemical Geology (2016)
Huan Cui, Alan J. Kaufman, Shuhai Xiao, Chuanming Zhou, Xiao-Ming Liu

The Ediacaran Period is characterized by the most profound negative carbon isotope (δ13C) excursion in Earth history, the Shuram Excursion. Various hypotheses – including the massive oxidation of dissolved organic carbon (DOC) in the oceans, the weathering of terrestrial organic carbon, or the release and oxidation of methane hydrates and/or expelled petroleum from the subsurface – have been proposed as sources of the 13C-depleted carbon. More recently, it has been suggested that global-scale precipitation of early authigenic carbonates, driven by anaerobic microbial metabolism in unconsolidated sediments, may have caused the Shuram Excursion, but empirical evidence is lacking. Here we present a comprehensive analysis of a Shuram-associated interval from the uppermost Doushantuo Formation in South China. Our study reveals petrographic evidence of methane-derived authigenic calcite (formed as early diagenetic cements and nodules) that are remarkably depleted in 13C – suggesting a buildup of alkalinity in pore fluids through the anaerobic oxidation of methane (AOM) – and systematically depleted in 18O relative to co-occurring dolomite. Early authigenesis of these minerals is likely to be driven by increased microbial sulfate reduction, triggered by enhanced continental weathering in the context of a marked rise in atmospheric oxygen levels. In light of the finding of methane-derived authigenic carbonates at Zhongling, and based on our basin-scale stratigraphic correlation, we hypothesize that the marked 13C and 18O depletion (including their co-variation noted worldwide) in the Shuram Excursion may reflect an episode of authigenesis occurring within a sulfate–methane transition zone (SMTZ). If true, the Shuram Excursion was then a global biogeochemical response to enhanced seawater sulfate concentration in the Ediacaran ocean driven by the Neoproterozoic oxidation of surface environments. This paleo-oceanographic transition may have therefore paved the way for subsequent evolution and diversification of animals. Our study highlights the significance of the integrated approach that combines petrography, mineralogy, and texture-specific micro-drilling geochemistry in chemostratigraphic studies. Such investigation on fully-expressed Shuram-equivalent sections may hold the promise to directly test our hypothesis.

Methane-derived authigenic carbonates from the uppermost Doushantuo Formation in South China: Was the Ediacaran Shuram Excursion a globally synchronized early diagenetic event?
Chemical Geology (2016)
Huan Cui, Alan J. Kaufman, Shuhai Xiao, Chuanming Zhou, Xiao-Ming Liu

The Ediacaran Period is characterized by the most profound negative carbon isotope (δ13C) excursion in Earth history, the Shuram Excursion. Various hypotheses – including the massive oxidation of dissolved organic carbon (DOC) in the oceans, the weathering of terrestrial organic carbon, or the release and oxidation of methane hydrates and/or expelled petroleum from the subsurface – have been proposed as sources of the 13C-depleted carbon. More recently, it has been suggested that global-scale precipitation of early authigenic carbonates, driven by anaerobic microbial metabolism in unconsolidated sediments, may have caused the Shuram Excursion, but empirical evidence is lacking. Here we present a comprehensive analysis of a Shuram-associated interval from the uppermost Doushantuo Formation in South China. Our study reveals petrographic evidence of methane-derived authigenic calcite (formed as early diagenetic cements and nodules) that are remarkably depleted in 13C – suggesting a buildup of alkalinity in pore fluids through the anaerobic oxidation of methane (AOM) – and systematically depleted in 18O relative to co-occurring dolomite. Early authigenesis of these minerals is likely to be driven by increased microbial sulfate reduction, triggered by enhanced continental weathering in the context of a marked rise in atmospheric oxygen levels. In light of the finding of methane-derived authigenic carbonates at Zhongling, and based on our basin-scale stratigraphic correlation, we hypothesize that the marked 13C and 18O depletion (including their co-variation noted worldwide) in the Shuram Excursion may reflect an episode of authigenesis occurring within a sulfate–methane transition zone (SMTZ). If true, the Shuram Excursion was then a global biogeochemical response to enhanced seawater sulfate concentration in the Ediacaran ocean driven by the Neoproterozoic oxidation of surface environments. This paleo-oceanographic transition may have therefore paved the way for subsequent evolution and diversification of animals. Our study highlights the significance of the integrated approach that combines petrography, mineralogy, and texture-specific micro-drilling geochemistry in chemostratigraphic studies. Such investigation on fully-expressed Shuram-equivalent sections may hold the promise to directly test our hypothesis.

Authigenic carbonate mounds from active methane seeps on the southern Aquitaine Shelf (Bay of Biscay, France): evidence for anaerobic oxidation of biogenic methane and submarine groundwater discharge during formation
Continental Shelf Research (2016)
Catherine Pierre, Jérome Demange, Marie-Madeleine Blanc-Valleron, Stéphanie Dupré

The widespread methane emissions that were discovered in 2013 on the Aquitaine Shelf at water depth between 140 and 220m are associated with authigenic carbonate crusts that cover meter-high subcircular reliefs of 10 to 100m in diameter. These authigenic carbonates are primarily aragonite plus calcite and dolomite, which cement the fine- to medium-grained sandy sediment. The carbonate cement is often pierced by numerous circular cavities of 5 to 10µm in diameter that are considered to be moulds of gas bubbles. Conversely, micron-sized cavities in the aragonite crystals are attributed to dissolution features, in relation to the production of CO2 during the aerobic oxidation of methane. The oxygen isotopic compositions of bulk carbonate (+1.7 to +3.7‰) and aragonite cements obtained from microsampling (-0.1 to +1.4‰) indicate that these carbonates were precipitated in mixtures of seawater and freshwater, i.e., in the context of submarine groundwater discharge at the seafloor. The carbon isotopic compositions of authigenic carbonates (-51.9 to -38.1‰) and of aragonite cements (-49.9 to -29.3‰) show that the dissolved inorganic carbon of pore fluids was mostly produced by the anaerobic oxidation of biogenic methane and also partly from the groundwater system.

Authigenic carbonate mounds from active methane seeps on the southern Aquitaine Shelf (Bay of Biscay, France): evidence for anaerobic oxidation of biogenic methane and submarine groundwater discharge during formation
Continental Shelf Research (2016)
Catherine Pierre, Jérome Demange, Marie-Madeleine Blanc-Valleron, Stéphanie Dupré

The widespread methane emissions that were discovered in 2013 on the Aquitaine Shelf at water depth between 140 and 220m are associated with authigenic carbonate crusts that cover meter-high subcircular reliefs of 10 to 100m in diameter. These authigenic carbonates are primarily aragonite plus calcite and dolomite, which cement the fine- to medium-grained sandy sediment. The carbonate cement is often pierced by numerous circular cavities of 5 to 10µm in diameter that are considered to be moulds of gas bubbles. Conversely, micron-sized cavities in the aragonite crystals are attributed to dissolution features, in relation to the production of CO2 during the aerobic oxidation of methane. The oxygen isotopic compositions of bulk carbonate (+1.7 to +3.7‰) and aragonite cements obtained from microsampling (-0.1 to +1.4‰) indicate that these carbonates were precipitated in mixtures of seawater and freshwater, i.e., in the context of submarine groundwater discharge at the seafloor. The carbon isotopic compositions of authigenic carbonates (-51.9 to -38.1‰) and of aragonite cements (-49.9 to -29.3‰) show that the dissolved inorganic carbon of pore fluids was mostly produced by the anaerobic oxidation of biogenic methane and also partly from the groundwater system.

High-resolution carbon isotope records of the Toarcian Oceanic Anoxic Event (Early Jurassic) from North America and implications for the global drivers of the Toarcian carbon cycle
Earth and Planetary Science Letters (2016)
T.R. Them, B.C. Gill, A.H. Caruthers, D.R. Gröcke, E.T. Tulsky, R.C. Martindale, T.P. Poulton, P.L. Smith

The Mesozoic Era experienced several instances of abrupt environmental change that are associated with instabilities in the climate, reorganizations of the global carbon cycle, and elevated extinction rates. Often during these perturbations, oxygen-deficient conditions developed in the oceans resulting in the widespread deposition of organic-rich sediments — these events are referred to as Oceanic Anoxic Events or OAEs. Such events have been linked to massive injections of greenhouse gases into the ocean–atmosphere system by transient episodes of voluminous volcanism and the destabilization of methane clathrates within marine environments. Nevertheless, uncertainty surrounds the specific environmental drivers and feedbacks that occurred during the OAEs that caused perturbations in the carbon cycle; this is particularly true of the Early Jurassic Toarcian OAE (∼183.1 Ma). Here, we present biostratigraphically constrained carbon isotope data from western North America (Alberta and British Columbia, Canada) to better assess the global extent of the carbon cycle perturbations. We identify the large negative carbon isotope excursion associated with the OAE along with high-frequency oscillations and steps within the onset of this excursion. We propose that these high-frequency carbon isotope excursions reflect changes to the global carbon cycle and also that they are related to the production and release of greenhouse gases from terrestrial environments on astronomical timescales. Furthermore, increased terrestrial methanogenesis should be considered an important climatic feedback during Ocean Anoxic Events and other similar events in Earth history after the proliferation of land plants.

High-resolution carbon isotope records of the Toarcian Oceanic Anoxic Event (Early Jurassic) from North America and implications for the global drivers of the Toarcian carbon cycle
Earth and Planetary Science Letters (2016)
T.R. Them, B.C. Gill, A.H. Caruthers, D.R. Gröcke, E.T. Tulsky, R.C. Martindale, T.P. Poulton, P.L. Smith

The Mesozoic Era experienced several instances of abrupt environmental change that are associated with instabilities in the climate, reorganizations of the global carbon cycle, and elevated extinction rates. Often during these perturbations, oxygen-deficient conditions developed in the oceans resulting in the widespread deposition of organic-rich sediments — these events are referred to as Oceanic Anoxic Events or OAEs. Such events have been linked to massive injections of greenhouse gases into the ocean–atmosphere system by transient episodes of voluminous volcanism and the destabilization of methane clathrates within marine environments. Nevertheless, uncertainty surrounds the specific environmental drivers and feedbacks that occurred during the OAEs that caused perturbations in the carbon cycle; this is particularly true of the Early Jurassic Toarcian OAE (∼183.1 Ma). Here, we present biostratigraphically constrained carbon isotope data from western North America (Alberta and British Columbia, Canada) to better assess the global extent of the carbon cycle perturbations. We identify the large negative carbon isotope excursion associated with the OAE along with high-frequency oscillations and steps within the onset of this excursion. We propose that these high-frequency carbon isotope excursions reflect changes to the global carbon cycle and also that they are related to the production and release of greenhouse gases from terrestrial environments on astronomical timescales. Furthermore, increased terrestrial methanogenesis should be considered an important climatic feedback during Ocean Anoxic Events and other similar events in Earth history after the proliferation of land plants.

Wet and cold climate conditions recorded by coral geochemical proxies during the beginning of the first millennium AD in the northern South China Sea
Journal of Asian Earth Sciences (2016)
Hangfang Xiao, Wenfeng Deng, Xuefei Chen, Gangjian Wei, Ti Zeng, Jian-xin Zhao

The past two millennia include some distinct climate intervals, such as the Medieval Warm Period (MWP) and the Little Ice Age (LIA), which were caused by natural forcing factors, as well as the Current Warm Period (CWP) that has been linked to anthropogenic factors. Therefore, this period has been of great interest to climate change researchers. However, most studies are based on terrestrial proxy records, historical documentary data, and simulation results, and the ocean and the tropical record are very limited. The Eastern Han, Three Kingdoms, and Western Jin periods (AD 25–316) cover the beginning first millennium AD in China, and were characterized by a cold climate and frequent wars and regime changes. This study used paired Sr/Ca and δ18O series recovered from a fossil coral to reconstruct the sea surface water conditions during the late Eastern Han to Western Jin periods (AD 167–309) at Wenchang, eastern Hainan Island in the northern South China Sea (SCS), to investigate climate change at this time. The long-term sea surface temperature (SST) during the study interval was 25.1 °C, which is about 1.5 °C lower than that of the CWP (26.6 °C). Compared with the average value of 0.40‰ during the CWP, the long-term average seawater δ18O (–0.06‰) was more negative. These results indicate that the climate conditions during the study period were cold and wet and comparable with those of the LIA. This colder climate may have been associated with the weaker summer solar irradiance. The wet conditions were caused by the reduced northward shift of the intertropical convergence zone/monsoon rainbelt associated with the retreat of the East Asian summer monsoon. Interannual and interdecadal climate variability may also have contributed to the variations in SST and seawater δ18O recorded over the study period.
Tags: carbon , oxygen , geol , clim , mulitcarb

D/H fractionation during the sublimation of water ice
Icarus (2016)
Christophe Lécuyer, Aurélien Royer, François Fourel, Magali Seris, Laurent Simon, François Robert

Experiments of sublimation of pure water ice have been performed in the temperature range -105°C to -30°C and atmospheric partial pressures ranging from 10−6 to 10−1 mb. Sampling of both vapour and residual ice fractions has been performed with the use of a vacuum line designed for the extraction and purification of gases before the measurement of their D/H ratios. Sublimation was responsible for sizable isotopic fractionation factors in the range 0.969 to 1.123 for temperatures lying between -105°C and -30°C. The fractionation factor exhibits a cross-over at temperatures around -50°C with the water vapour fraction being D-depleted relative to the residual ice fraction at T<-50°C (αice-vapour=0.969 to 0.995). This cross-over has implications for the understanding of the atmospheric water cycle of some terrestrial planets such as the Earth or Mars. The magnitude of deuterium enrichment or depletion between ice and water vapour cannot explain the differences in the D/H ratios amongst Jupiter comets and long–period comets families nor those that have been documented between Earth's and cometary water.

Wet and cold climate conditions recorded by coral geochemical proxies during the beginning of the first millennium AD in the northern South China Sea
Journal of Asian Earth Sciences (2016)
Hangfang Xiao, Wenfeng Deng, Xuefei Chen, Gangjian Wei, Ti Zeng, Jian-xin Zhao

The past two millennia include some distinct climate intervals, such as the Medieval Warm Period (MWP) and the Little Ice Age (LIA), which were caused by natural forcing factors, as well as the Current Warm Period (CWP) that has been linked to anthropogenic factors. Therefore, this period has been of great interest to climate change researchers. However, most studies are based on terrestrial proxy records, historical documentary data, and simulation results, and the ocean and the tropical record are very limited. The Eastern Han, Three Kingdoms, and Western Jin periods (AD 25–316) cover the beginning first millennium AD in China, and were characterized by a cold climate and frequent wars and regime changes. This study used paired Sr/Ca and δ18O series recovered from a fossil coral to reconstruct the sea surface water conditions during the late Eastern Han to Western Jin periods (AD 167–309) at Wenchang, eastern Hainan Island in the northern South China Sea (SCS), to investigate climate change at this time. The long-term sea surface temperature (SST) during the study interval was 25.1 °C, which is about 1.5 °C lower than that of the CWP (26.6 °C). Compared with the average value of 0.40‰ during the CWP, the long-term average seawater δ18O (–0.06‰) was more negative. These results indicate that the climate conditions during the study period were cold and wet and comparable with those of the LIA. This colder climate may have been associated with the weaker summer solar irradiance. The wet conditions were caused by the reduced northward shift of the intertropical convergence zone/monsoon rainbelt associated with the retreat of the East Asian summer monsoon. Interannual and interdecadal climate variability may also have contributed to the variations in SST and seawater δ18O recorded over the study period.
Tags: carbon , oxygen , geol , clim , mulitcarb

D/H fractionation during the sublimation of water ice
Icarus (2016)
Christophe Lécuyer, Aurélien Royer, François Fourel, Magali Seris, Laurent Simon, François Robert

Experiments of sublimation of pure water ice have been performed in the temperature range -105°C to -30°C and atmospheric partial pressures ranging from 10−6 to 10−1 mb. Sampling of both vapour and residual ice fractions has been performed with the use of a vacuum line designed for the extraction and purification of gases before the measurement of their D/H ratios. Sublimation was responsible for sizable isotopic fractionation factors in the range 0.969 to 1.123 for temperatures lying between -105°C and -30°C. The fractionation factor exhibits a cross-over at temperatures around -50°C with the water vapour fraction being D-depleted relative to the residual ice fraction at T<-50°C (αice-vapour=0.969 to 0.995). This cross-over has implications for the understanding of the atmospheric water cycle of some terrestrial planets such as the Earth or Mars. The magnitude of deuterium enrichment or depletion between ice and water vapour cannot explain the differences in the D/H ratios amongst Jupiter comets and long–period comets families nor those that have been documented between Earth's and cometary water.