scholarly journals Faunal/floral and isotopic responses to Milankovitch precession cycles and environmental changes in the upper Gulpen Formation (Upper Maastrichtian) at the CBR-Lixhe and ENCI-Maastricht bv quarries

2003 ◽  
Vol 82 (3) ◽  
pp. 275-281 ◽  
Author(s):  
P.J. Felder ◽  
E. Keppens ◽  
B. Declercq ◽  
S. Normand ◽  
M. Streel
Keyword(s):  
Stable Isotope ◽  
Temperate Forest ◽  
Turning Point ◽  
Environmental Changes ◽  
Pollen Grains ◽  
Oxygen Isotopic Composition ◽  
Climatic Fluctuations ◽  
Oxygen Isotopic ◽  
Insight Into ◽  
Upper Maastrichtian

AbstractTwo sections, just below the Nivelle Horizon in the upper Gulpen Formation (Upper Maastrichtian), and seven kilometres apart (CBR-Lixhe and ENCI-Maastricht bv quarries) have been analysed (samples every 5 cm) for dinocyst, pollen grains and bioclast contents as well as for carbon and oxygen isotopic composition, to obtain better insight into the influence of weathering on these sediments. The CBR section lies above groundwater level, while that at the ENCI quarry is some metres below. At the former quarry we recognised the influences of weathering (karst) nearby.At ENCI, palynological, bioclast and stable isotope results of the carbonate phase (mainly consisting of coccoliths) co-vary remarkably, displaying two cycles which may be interpreted tentatively as climatic fluctuations. The ∂18O curve varies roughly between −1.6‰ and −1.1‰ (on PDB scale), corresponding to a temperature change of about 2°C. Less negative values (i.e. cooler seawater) coincide with larger amounts of pollen of Normapolles and Triporates type assumed to represent temperate forest elements of a vegetation also containing tropical elements such as palms. Assuming the 5 cm sample intervals at ENCI to correspond to 1 ka, climatic maxima (and minima) may be 20–25 ka apart, obviously recalling Milankovitch precession cycles.These are independent of a sharp sedimentological change noted in the upper part of the lowest cycle (samples 42 to 24). Upwards of sample 42, bioclast contents increase and dinocysts, Spiniferites in particular, decrease significantly, corresponding to a marked shallowing. This turning point is also recorded in the ∂13C curve at ENCI. Bioclast percentages appear to follow composite trends that are influenced by both climatic and sedimentological conditions.

scholarly journals Interpretation of benthic foraminiferal stable isotopes in subtidal estuarine environments

2009 ◽  
Vol 6 (11) ◽  
pp. 2549-2560 ◽  
Author(s):  
P. Diz ◽  
F. J. Jorissen ◽  
G. J. Reichart ◽  
C. Poulain ◽  
F. Dehairs ◽  
...  
Keyword(s):  
Stable Isotope ◽  
River Estuary ◽  
Early Spring ◽  
Lower Estuary ◽  
Novel Approach ◽  
New Information ◽  
Stable Isotopic ◽  
Stable Isotope Signatures ◽  
Oxygen Isotopic ◽  
Insight Into

Abstract. Here we present a novel approach for the interpretation of stable isotope signatures recorded in benthic foraminifera from subtidal estuarine environments. The stable isotopic composition (δ18O and δ13C) of living Ammonia tepida and Haynesina germanica is examined at four stations in the Auray River estuary (Gulf of Morbihan, France) sampled in two contrasting seasons, spring 2006 and winter 2007. Comparing benthic foraminiferal δ18O measurements with theoretical oxygen isotopic equilibrium values, calculated on the basis of water temperature and salinity measurements in the upper and lower estuary, i.e., T-S-δ18Oeq. diagrams, strongly suggests that foraminiferal faunas sampled at the four stations calcified during different periods of the year. This interpretation can be refined by using the benthic foraminiferal δ13C, which is mainly determined by the mixing of sea and river water. In the upper estuary foraminifera mainly calcified in early spring and winter, whereas in the lower estuary calcification mainly took place in spring, summer and autumn. This new method provides insight into the complexity of estuarine benthic foraminiferal stable isotope records. In addition, it can also be used to obtain new information on preferred calcification periods of benthic foraminiferal taxa in different parts of the estuary.

Biostratigraphical correlation of the Campanian–Maastrichtian boundary: Lägerdorf–Hemmoor (northwestern Germany), DSDP Sites 548A, 549 and 551 (eastern North Atlantic) with palaeobiogeographical and palaeoceanographical implications

1991 ◽  
Vol 128 (5) ◽  
pp. 479-503 ◽  
Author(s):  
Joachim Schönfeld ◽  
Jackie Burnett
Keyword(s):  
North Atlantic ◽  
Oxygen Isotopic Composition ◽  
Planktonic Foraminifers ◽  
Shelf Sea ◽  
Oxygen Isotopic ◽  
Eastern North Atlantic ◽  
Water Outflow ◽  
Upper Maastrichtian ◽  
Upper Campanian ◽  
Goban Spur

AbstractA correlation of the Campanian–Maastrichtian boundary is attempted using foraminiferal and nannoplankton data from two areas: the eastern North Atlantic and northwestern Germany. The Boreal benthic and Tethyan planktonic foraminiferal zonation schemes are applied to Site 548A, where both foraminiferal groups occur frequently. A direct comparison of both biozonations reveals that the base of the Maastrichtian, according to planktonic foraminifers, has to be placed in the Upper Campanian of the Boreal benthic foraminiferal biozonation, which concurs with the nannoplankton results. The Tethyan Middle and Upper Maastrichtian are probably equivalent to the Upper Maastrichtian in the Boreal sense. The bases of the Maastrichtian substages are thus diachronous between the Boreal and Tethyan realms. Palaeotemperatures (which were estimated using the oxygen isotopic composition of the Goban Spur chalks) indicate, in combination with palaeowind directions, that the faunal and floral distribution pattern recorded is the result of a stable, warm water outflow from the northwest European epicontinental seas through the Channel area to the Celtic Shelf sea and Goban Spur. This mechanism appears to have been a dominant separating factor of the Boreal and Tethyan bioprovinces on the western European Shelf.

scholarly journals Interpretation of benthic foraminiferal stable isotopes in subtidal estuarine environments

2009 ◽  
Vol 6 (4) ◽  
pp. 7453-7480
Author(s):  
P. Diz ◽  
F. J. Jorissen ◽  
G. J. Reichart ◽  
C. Poulain ◽  
F. Dehairs ◽  
...  
Keyword(s):  
Stable Isotope ◽  
River Estuary ◽  
Early Spring ◽  
Lower Estuary ◽  
Novel Approach ◽  
New Information ◽  
Stable Isotopic ◽  
Stable Isotope Signatures ◽  
Oxygen Isotopic ◽  
Insight Into

Abstract. Here we present a novel approach for the interpretation of stable isotope signatures recorded in benthic foraminifera from subtidal estuarine environments. The stable isotopic composition (δ18O and δ13C) of living Ammonia tepida and Haynesina germanica is examined in four stations in the Auray River estuary (Gulf of Morbihan, France) sampled in two contrasting seasons, spring 2006 and winter 2007. Comparing benthic foraminiferal δ18O measurements with theoretical oxygen isotopic equilibrium values, calculated on the basis of water temperature and salinity measurements in the upper and lower estuary, i.e., T−S−δ18Oeq. diagrams, strongly suggests that foraminiferal faunas sampled at the four stations calcified during different periods of the year. This interpretation can be refined by using the benthic foraminiferal δ13C which is mainly determined by the mixing of sea and river water. In the upper estuary foraminifera mainly calcified in early spring and winter, whereas in the lower estuary calcification took mainly place in spring, summer and autumn. This new method provides insight into the complexity of estuarine benthic foraminiferal stable isotope records. In addition, it can also be used to obtain new information on preferred calcification periods of benthic foraminiferal taxa in different parts of the estuary.

scholarly journals Revealing the climate of snowball Earth from Δ17O systematics of hydrothermal rocks

2015 ◽  
Vol 112 (17) ◽  
pp. 5337-5341 ◽  
Author(s):  
Daniel Herwartz ◽  
Andreas Pack ◽  
Dmitri Krylov ◽  
Yilin Xiao ◽  
Karlis Muehlenbachs ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Oxygen Isotope ◽  
Water Samples ◽  
Isotope Composition ◽  
Oxygen Isotopic Composition ◽  
Snowball Earth ◽  
Climate Conditions ◽  
Oxygen Isotopic ◽  
Mass Dependent ◽  
Insight Into

The oxygen isotopic composition of hydrothermally altered rocks partly originates from the interacting fluid. We use the triple oxygen isotope composition (17O/16O, 18O/16O) of Proterozoic rocks to reconstruct the 18O/16O ratio of ancient meteoric waters. Some of these waters have originated from snowball Earth glaciers and thus give insight into the climate and hydrology of these critical intervals in Earth history. For a Paleoproterozoic [∼2.3–2.4 gigayears ago (Ga)] snowball Earth, δ18O = −43 ± 3‰ is estimated for pristine meteoric waters that precipitated at low paleo-latitudes (≤35°N). Today, such low 18O/16O values are only observed in central Antarctica, where long distillation trajectories in combination with low condensation temperatures promote extreme 18O depletion. For a Neoproterozoic (∼0.6–0.7 Ga) snowball Earth, higher meltwater δ18O estimates of −21 ± 3‰ imply less extreme climate conditions at similar paleo-latitudes (≤35°N). Both estimates are single snapshots of ancient water samples and may not represent peak snowball Earth conditions. We demonstrate how 17O/16O measurements provide information beyond traditional 18O/16O measurements, even though all fractionation processes are purely mass dependent.

Climate, water and CO2: a geological perspective

2008 ◽  
Vol 72 (1) ◽  
pp. 293-294
Author(s):  
J. Veizer
Keyword(s):  
Stable Isotope ◽  
Isotopic Composition ◽  
Oxygen Isotope ◽  
Isotope Geochemistry ◽  
Oxygen Isotopic Composition ◽  
Stable Isotope Geochemistry ◽  
Temperature Signal ◽  
Oxygen Isotopic ◽  
Time Periods

The development of a palaeothermometer for ancient oceans has been a prime goal of stable isotope geochemistry since its inception in the middle of the last century. Following the calibration of the calcite oxygen isotope palaeothermometer by Epstein et al. (1953), and expanding on the seminal papers by Cesare Emiliani, the technique blossomed into a widely applied tool of palaeoceanography. These studies resulted in major advances in our understanding of Quaternary, and to some extent Tertiary oceans, but for older time periods the effort is mired by controversy and is at a standstill. In part this is due to the dearth of well-characterized carrier phases for the temperature signal, such as foraminifera shells, in the pre-Tertiary strata, but an intractable disagreement among practitioners as to the oxygen isotopic composition of ancient seawater is probably a more important stumbling block.

Changes of Ionic and Oxygen Isotopic Composition of the Snowpack at the Glacier Austre Okstindbreen, Norway, 1995

1998 ◽  
Vol 29 (1) ◽  
pp. 1-20 ◽  
Author(s):  
Peter Raben ◽  
Wilfred H. Theakstone
Keyword(s):  
Isotopic Composition ◽  
Sea Level ◽  
Oxygen Isotopes ◽  
Oxygen Isotopic Composition ◽  
Isotopic Ratios ◽  
Vertical Variations ◽  
Oxygen Isotopic ◽  
The Difference ◽  
Liquid Precipitation ◽  
Different Altitudes

Marked vertical variations of ions and oxygen isotopes were present in the snowpack at the glacier Austre Okstindbreen during the pre-melting phase in 1995 at sites between 825 m and 1,470 m above sea level. As the first meltwater percolated from the top of the pack, ions were moved to a greater depth, but the isotopic composition remained relatively unchanged. Ions continued to move downwards through the pack during the melting phase, even when there was little surface melting and no addition of liquid precipitation. The at-a-depth correlation between ionic concentrations and isotopic ratios, strong in the pre-melting phase, weakened during melting. In August, concentrations of Na+ and Mg2+ ions in the residual pack were low and vertical variations were slight; 18O enrichment had occurred. The difference of the time at which melting of the snowpack starts at different altitudes influences the input of ions and isotopes to the underlying glacier.

scholarly journals Cytotype distribution and chloroplast phylogeography of the Actinidia chinensis complex

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Zhi Wang ◽  
Caihong Zhong ◽  
Dawei Li ◽  
Chunlin Yan ◽  
Xiaohong Yao ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Demographic History ◽  
Wide Distribution ◽  
Historical Demography ◽  
Actinidia Chinensis ◽  
Ecological Niche Models ◽  
Subtropical China ◽  
Modeling Tools ◽  
Climatic Fluctuations ◽  
Ploidy Levels

Abstract Background Plant phylogeographic studies of species in subtropical China have mainly focused on rare and endangered species, whereas few studies have been conducted on taxa with relatively wide distribution, especially polyploid species. We investigated the cytotype and haplotype distribution pattern of the Actinidia chinensis complex, a widespread geographically woody liana with variable ploidy in subtropical China comprising two varieties, with three chloroplast fragments DNA (ndhF-rpl132, rps16-trnQ and trnE-trnT). Macroevolutionary, microevolutionary and niche modeling tools were also combined to disentangle the origin and the demographic history of the species or cytotypes. Results The ploidy levels of 3338 individuals from 128 populations sampled throughout the species distribution range were estimated with flow cytometry. The widespread cytotypes were diploids followed by tetraploids and hexaploids, whereas triploids and octoploids occurred in a few populations. Thirty-one chloroplast haplotypes were detected. The genetic diversity and genetic structure were found to be high between varieties (or ploidy races) chinensis and deliciosa. Our results revealed that these two varieties inhabit significantly different climatic niche spaces. Ecological niche models (ENMs) indicate that all varieties’ ranges contracted during the Last Inter Glacial (LIG), and expanded eastward or northward during the Last Glacial Maximum (LGM). Conclusions Pliocene and Plio-Pleistocene climatic fluctuations and vicariance appear to have played key roles in shaping current population structure and historical demography in the A. chinensis complex. The polyploidization process also appears to have played an important role in the historical demography of the complex through improving their adaptability to environmental changes.

scholarly journals Assessment of Pollution Sources and Contribution in Urban Dust Using Metal Concentrations and Multi-Isotope Ratios (13C, 207/206Pb) in a Complex Industrial Port Area, Korea

Atmosphere ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 840
Author(s):  
Min-Seob Kim ◽  
Jee-Young Kim ◽  
Jaeseon Park ◽  
Suk-Hee Yeon ◽  
Sunkyoung Shin ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Environmental Changes ◽  
Isotope Ratios ◽  
Residential Area ◽  
Control Area ◽  
Pollution Sources ◽  
Raw Material ◽  
Urban Dust ◽  
Metal Concentrations ◽  
Mn Ore

The metal concentrations and isotopic compositions (13C, 207/206Pb) of urban dust, topsoil, and PM10 samples were analyzed in a residential area near Donghae port, Korea, which is surrounded by various types of industrial factories and raw material stockpiled on empty land, to determine the contributions of the main pollution sources (i.e., Mn ore, Zn ore, cement, coal, coke, and topsoil). The metal concentrations of urban dust in the port and residential area were approximately 85~112 times higher (EF > 100) in comparison with the control area (EF < 2), especially the Mn and Zn ions, indicating they were mainly derived from anthropogenic source. These ions have been accumulating in urban dust for decades; furthermore, the concentration of PM10 is seven times higher than that of the control area, which means that contamination is even present. The isotopic (13C, 207/206Pb) values of the pollution sources were highly different, depending on the characteristics of each source: cement (−19.6‰, 0.8594‰), Zn ore (−24.3‰, 0.9175‰), coal (−23.6‰, 0.8369‰), coke (−27.0‰, 0.8739‰), Mn ore (−24.9‰, 0.9117‰), soil (−25.2‰, 0.7743‰). As a result of the evaluated contributions of pollution source on urban dust through the Iso-source and SIAR models using stable isotope ratios (13C, 207/206Pb), we found that the largest contribution of Mn (20.4%) and Zn (20.3%) ions are derived from industrial factories and ore stockpiles on empty land (Mn and Zn). It is suggested that there is a significant influence of dust scattered by wind from raw material stockpiles, which are stacked near ports or factories. Therefore, there is evidence to support the idea that port activities affect the air quality of residence areas in a city. Our results may indicate that metal concentrations and their stable isotope compositions can predict environmental changes and act as a powerful tool to trace the past and present pollution history in complex contexts associated with peri-urban regions.

scholarly journals Precise regulation of the relative rates of surface area and volume synthesis in bacterial cells growing in dynamic environments

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Handuo Shi ◽  
Yan Hu ◽  
Pascal D. Odermatt ◽  
Carlos G. Gonzalez ◽  
Lichao Zhang ◽  
...  
Keyword(s):  
Growth Rate ◽  
Time Delay ◽  
Surface Area ◽  
Environmental Changes ◽  
Volume Ratio ◽  
Dynamic Environments ◽  
Bacterial Cells ◽  
Bacterial Growth Rate ◽  
State Size ◽  
Insight Into

AbstractThe steady-state size of bacterial cells correlates with nutrient-determined growth rate. Here, we explore how rod-shaped bacterial cells regulate their morphology during rapid environmental changes. We quantify cellular dimensions throughout passage cycles of stationary-phase cells diluted into fresh medium and grown back to saturation. We find that cells exhibit characteristic dynamics in surface area to volume ratio (SA/V), which are conserved across genetic and chemical perturbations as well as across species and growth temperatures. A mathematical model with a single fitting parameter (the time delay between surface and volume synthesis) is quantitatively consistent with our SA/V experimental observations. The model supports that this time delay is due to differential expression of volume and surface-related genes, and that the first division after dilution occurs at a tightly controlled SA/V. Our minimal model thus provides insight into the connections between bacterial growth rate and cell shape in dynamic environments.

Oxygen isotopes in terrestrial gastropod shells track Quaternary climate change in the American Southwest

2021 ◽  
pp. 1-11
Author(s):  
Jason A. Rech ◽  
Jeffrey S. Pigati ◽  
Kathleen B. Springer ◽  
Stephanie Bosch ◽  
Jeffrey C. Nekola ◽  
...  
Keyword(s):  
Climate Change ◽  
Oxygen Isotopic Composition ◽  
American Southwest ◽  
Quaternary Climate ◽  
San Pedro ◽  
Spatial Coverage ◽  
Oxygen Isotopic ◽  
The Last Glacial Maximum ◽  
The Last Glacial ◽  
Terrestrial Gastropod

Abstract Recent studies have shown the oxygen isotopic composition (δ18O) of modern terrestrial gastropod shells is determined largely by the δ18O of precipitation. This implies that fossil shells could be used to reconstruct the δ18O of paleo-precipitation as long as the isotopic system, including the hydrologic pathways of the local watershed and the gastropod systematics, is well understood. In this study, we measured the δ18O values of 456 individual gastropod shells collected from paleowetland deposits in the San Pedro Valley, Arizona that range in age from ca. 29.1 to 9.8 ka. Isotopic differences of up to 2‰ were identified among the four taxa analyzed (Succineidae, Pupilla hebes, Gastrocopta tappaniana, and Vallonia gracilicosta), with Succineidae shells yielding the highest values and V. gracilicosta shells exhibiting the lowest values. We used these data to construct a composite isotopic record that incorporates these taxonomic offsets, and found shell δ18O values increased by ~4‰ between the last glacial maximum and early Holocene, which is similar to the magnitude, direction, and rate of isotopic change recorded by speleothems in the region. These results suggest the terrestrial gastropods analyzed here may be used as a proxy for past climate in a manner that is complementary to speleothems, but potentially with much greater spatial coverage.

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