Lorenz Schwark | Christian-Albrechts-Universität zu Kiel (original) (raw)
Papers by Lorenz Schwark
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29th International Meeting on Organic Geochemistry, 2019
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Scientific Reports, 2020
Throughout Earth’s history, variations in atmospheric CO2 concentration modulated climate. Unders... more Throughout Earth’s history, variations in atmospheric CO2 concentration modulated climate. Understanding changes in atmospheric carbon cycle is therefore pivotal in predicting consequences of recent global warming. Here, we report stable carbon isotopes (δ13C) of molecular land plant fossils complemented by bulk organic and inorganic carbon fractions for early Toarcian (Early Jurassic) sediments that coincided with global warming and a carbon cycle perturbation. The carbon cycle perturbation is expressed by a negative excursion in the δ13C records established for the different substrates. Based on differences in the magnitude of the carbon isotope excursion recorded in land plants and marine substrates we infer that the early Toarcian warming was paralleled by an increase in atmospheric CO2 levels from ~500 ppmv to ~1000 ppmv. Our data suggest that rising atmospheric CO2 levels resulted from the injection of 12C-enriched methane and its subsequent oxidation to CO2. Based on the cyc...
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The younger Quaternary erosion history was reconstructed in a catchment close to the Chalcolithic... more The younger Quaternary erosion history was reconstructed in a catchment close to the Chalcolithic giant settlement Maidanetske, central Ukraine based on dated sediment sequences. Four trenches and a long percussion drill-core were analyzed in a valley grading from a Loess covered plateau towards the Talianky River. The sediments were dated via a combination of radiocarbon dating, optical stimulated luminescence (OSL) and embedded artefacts. A suspicious non-coincidence between phases of soil erosion and the settlement history at the site over long periods of the Holocene is noticeable and suggests a climatically driven erosion at the site. The detected phases of erosion during the past >20,000 years coincide with global (cal 27.6 +/- 1.3 kyrs BP, 12.0 +/- 0.4 kyrs BP), northern hemispheric (cal 8.5 ± 0.3 kyrs BP), Mediterranean (cal 3.93 ± 0.1 kyrs BP) as well as western to central European (2,700 to 2,000 cal BP) climate anomalies. For these anomalies, characterized by colder th...
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Estimating the environmental and societal impact of recent volcanic eruptions is a task aided by ... more Estimating the environmental and societal impact of recent volcanic eruptions is a task aided by direct measurements and historical sources. Beyond the reach of first-hand accounts, our understanding of pre-historic volcanism is often hindered by the dating uncertainties inherent to stratigraphic archives. Here, we minimise this source of error by analysing the annually laminated sequences of two European lakes. We focus on environmental transformations that occurred in the decades preceding and following the deposition of the Icelandic Saksunarvatn tephra, dated between ca. 10,300 and 10,200 cal. BP. Evidence for continuous eruptive activity pre-dates the tephra deposition by nearly two decades, revealing a period of sustained volcanism and its effects on aquatic and terrestrial ecosystems. These results provide a new insight into the spatial and temporal effects of clustered volcanic eruptions. As such, they might prove useful to refine the simulation of volcanic forcing on contin...
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The ISME Journal, 2019
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Plants, in particular trees with specific habitat demands are excellent indicators of climate sta... more Plants, in particular trees with specific habitat demands are excellent indicators of climate state. Vegetation successions in subrecent and deep geologic time is recorded in fossil macro-remains or pollen accumulating in geological archives like limnic and marine sediments, peat bogs and mires. Birch trees in Europe form a major part in plant successions and constitute the dwarf species Betula nana and Betula humilis representing cold-adapted habitats or climates and two tree birches, Betula pubescens and Betula pendula characteristic for temperate habitats or climates. These birch species exhibit highly similar pollen shape and size, preventing their unambiguous application as paleoclimate/paleovegetation proxies. We here present a chemotaxonomic differentiation of the four European birch species based on their epicuticular wax lipids. The dominating lipid classes in epicuticular birch waxes were found to be n-alkanes (in the range of n-C23 to n-C33), straight-chain primary alcoho...
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The APPEA Journal, 2006
The history of petroleum exploration in central Australia has been enlivened by vigorous debate a... more The history of petroleum exploration in central Australia has been enlivened by vigorous debate about the source(s) of the oil and condensate found in the Cooper/Eromanga basin couplet. While early workers quickly recognized the source potential of thick Permian coal seams in the Patchawarra and Toolachee Formations, it took some time for the Jurassic Birkhead Formation and the Cretaceous Murta Formation to become accepted as effective source rocks. Although initially an exploration target, the Cambrian sediments of the underlying Warburton Basin subsequently were never seriously considered to have participated in the oil play, possibly due to a lack of subsurface information as a consequence of limited penetration by only a few widely spaced wells. Dismissal of the Warburton sequence as a source of hydrocarbons was based on its low generative potential as measured by total organic carbon (TOC) and Rock-Eval pyrolysis analyses. As most of the core samples analysed came from the uppe...
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Biogeosciences, 2015
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Chemical Geology, 2015
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The Holocene, 2004
A sediment core from Lake Pichozero (6146'; N, 3725'; E 118 m a.s.l.) provides informatio... more A sediment core from Lake Pichozero (6146'; N, 3725'; E 118 m a.s.l.) provides information on the environmental and climatic conditions in southeastern Russian Karelia during the Lateglacial and early Holocene (12 800-9300 cal. BP). The chronology of the sequence is constrainied by varve counting and AMS 14C measurement of terrestrial plant macrofossils. Multiproxy analyses (magnetic susceptibility, grain size, TOC, TN, TS, Rock Eval, pollen and macrofossils) imply that cold and dry regional climatic conditions with sparse Arctic vegetation prevailed prior to 11500 cal. BP. Coincident with the transition to the Holocene at 11 500 cal. BP, air temperatures and lake productivity increased and Betula pubescens and Populus treinula started to migrate into the area, followed by Picea abies at 10 750 cal. BP. Although lake productivity decreased at around 11 000 cal. BP and remained low until 9600 cal. BP, pollen-based climate reconstructions imply variable climatic conditions in ...
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Quaternary Science Reviews, 2013
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Organic Geochemistry, 2013
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Geology, 2013
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European Journal of Soil Science, 2006
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Environmental Microbiology, 2013
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Biogeosciences, 2012
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Palaeogeography, Palaeoclimatology, Palaeoecology, 2016
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Geomorphology, 2020
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29th International Meeting on Organic Geochemistry, 2019
Bookmarks Related papers MentionsView impact
Scientific Reports, 2020
Throughout Earth’s history, variations in atmospheric CO2 concentration modulated climate. Unders... more Throughout Earth’s history, variations in atmospheric CO2 concentration modulated climate. Understanding changes in atmospheric carbon cycle is therefore pivotal in predicting consequences of recent global warming. Here, we report stable carbon isotopes (δ13C) of molecular land plant fossils complemented by bulk organic and inorganic carbon fractions for early Toarcian (Early Jurassic) sediments that coincided with global warming and a carbon cycle perturbation. The carbon cycle perturbation is expressed by a negative excursion in the δ13C records established for the different substrates. Based on differences in the magnitude of the carbon isotope excursion recorded in land plants and marine substrates we infer that the early Toarcian warming was paralleled by an increase in atmospheric CO2 levels from ~500 ppmv to ~1000 ppmv. Our data suggest that rising atmospheric CO2 levels resulted from the injection of 12C-enriched methane and its subsequent oxidation to CO2. Based on the cyc...
Bookmarks Related papers MentionsView impact
The younger Quaternary erosion history was reconstructed in a catchment close to the Chalcolithic... more The younger Quaternary erosion history was reconstructed in a catchment close to the Chalcolithic giant settlement Maidanetske, central Ukraine based on dated sediment sequences. Four trenches and a long percussion drill-core were analyzed in a valley grading from a Loess covered plateau towards the Talianky River. The sediments were dated via a combination of radiocarbon dating, optical stimulated luminescence (OSL) and embedded artefacts. A suspicious non-coincidence between phases of soil erosion and the settlement history at the site over long periods of the Holocene is noticeable and suggests a climatically driven erosion at the site. The detected phases of erosion during the past >20,000 years coincide with global (cal 27.6 +/- 1.3 kyrs BP, 12.0 +/- 0.4 kyrs BP), northern hemispheric (cal 8.5 ± 0.3 kyrs BP), Mediterranean (cal 3.93 ± 0.1 kyrs BP) as well as western to central European (2,700 to 2,000 cal BP) climate anomalies. For these anomalies, characterized by colder th...
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Estimating the environmental and societal impact of recent volcanic eruptions is a task aided by ... more Estimating the environmental and societal impact of recent volcanic eruptions is a task aided by direct measurements and historical sources. Beyond the reach of first-hand accounts, our understanding of pre-historic volcanism is often hindered by the dating uncertainties inherent to stratigraphic archives. Here, we minimise this source of error by analysing the annually laminated sequences of two European lakes. We focus on environmental transformations that occurred in the decades preceding and following the deposition of the Icelandic Saksunarvatn tephra, dated between ca. 10,300 and 10,200 cal. BP. Evidence for continuous eruptive activity pre-dates the tephra deposition by nearly two decades, revealing a period of sustained volcanism and its effects on aquatic and terrestrial ecosystems. These results provide a new insight into the spatial and temporal effects of clustered volcanic eruptions. As such, they might prove useful to refine the simulation of volcanic forcing on contin...
Bookmarks Related papers MentionsView impact
The ISME Journal, 2019
Bookmarks Related papers MentionsView impact
Plants, in particular trees with specific habitat demands are excellent indicators of climate sta... more Plants, in particular trees with specific habitat demands are excellent indicators of climate state. Vegetation successions in subrecent and deep geologic time is recorded in fossil macro-remains or pollen accumulating in geological archives like limnic and marine sediments, peat bogs and mires. Birch trees in Europe form a major part in plant successions and constitute the dwarf species Betula nana and Betula humilis representing cold-adapted habitats or climates and two tree birches, Betula pubescens and Betula pendula characteristic for temperate habitats or climates. These birch species exhibit highly similar pollen shape and size, preventing their unambiguous application as paleoclimate/paleovegetation proxies. We here present a chemotaxonomic differentiation of the four European birch species based on their epicuticular wax lipids. The dominating lipid classes in epicuticular birch waxes were found to be n-alkanes (in the range of n-C23 to n-C33), straight-chain primary alcoho...
Bookmarks Related papers MentionsView impact
The APPEA Journal, 2006
The history of petroleum exploration in central Australia has been enlivened by vigorous debate a... more The history of petroleum exploration in central Australia has been enlivened by vigorous debate about the source(s) of the oil and condensate found in the Cooper/Eromanga basin couplet. While early workers quickly recognized the source potential of thick Permian coal seams in the Patchawarra and Toolachee Formations, it took some time for the Jurassic Birkhead Formation and the Cretaceous Murta Formation to become accepted as effective source rocks. Although initially an exploration target, the Cambrian sediments of the underlying Warburton Basin subsequently were never seriously considered to have participated in the oil play, possibly due to a lack of subsurface information as a consequence of limited penetration by only a few widely spaced wells. Dismissal of the Warburton sequence as a source of hydrocarbons was based on its low generative potential as measured by total organic carbon (TOC) and Rock-Eval pyrolysis analyses. As most of the core samples analysed came from the uppe...
Bookmarks Related papers MentionsView impact
Biogeosciences, 2015
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Chemical Geology, 2015
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
The Holocene, 2004
A sediment core from Lake Pichozero (6146'; N, 3725'; E 118 m a.s.l.) provides informatio... more A sediment core from Lake Pichozero (6146'; N, 3725'; E 118 m a.s.l.) provides information on the environmental and climatic conditions in southeastern Russian Karelia during the Lateglacial and early Holocene (12 800-9300 cal. BP). The chronology of the sequence is constrainied by varve counting and AMS 14C measurement of terrestrial plant macrofossils. Multiproxy analyses (magnetic susceptibility, grain size, TOC, TN, TS, Rock Eval, pollen and macrofossils) imply that cold and dry regional climatic conditions with sparse Arctic vegetation prevailed prior to 11500 cal. BP. Coincident with the transition to the Holocene at 11 500 cal. BP, air temperatures and lake productivity increased and Betula pubescens and Populus treinula started to migrate into the area, followed by Picea abies at 10 750 cal. BP. Although lake productivity decreased at around 11 000 cal. BP and remained low until 9600 cal. BP, pollen-based climate reconstructions imply variable climatic conditions in ...
Bookmarks Related papers MentionsView impact
Quaternary Science Reviews, 2013
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Organic Geochemistry, 2013
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Geology, 2013
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European Journal of Soil Science, 2006
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Environmental Microbiology, 2013
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Biogeosciences, 2012
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Palaeogeography, Palaeoclimatology, Palaeoecology, 2016
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Geomorphology, 2020
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