Impacts of arid land shrub expansion on soil carbon cycling from [superscript 14]C ages and carbon and oxygen isotope ratios of pedogenic calcite and organic matter.

1996 ◽  
Author(s):  
Sean Connin
Keyword(s):  
Organic Matter ◽  
Soil Carbon ◽  
Oxygen Isotope ◽  
Carbon Cycling ◽  
Isotope Ratios ◽  
Arid Land ◽  
Shrub Expansion ◽  
Soil Carbon Cycling ◽  
Oxygen Isotope Ratios ◽  
Carbon And Oxygen Isotope

scholarly journals Carbon and oxygen isotope ratios of tree ring cellulose along a precipitation transect in Oregon, United States

2005 ◽  
Vol 110 (G2) ◽  
pp. n/a-n/a ◽  
Author(s):  
John S. Roden ◽  
David R. Bowling ◽  
Nate G. McDowell ◽  
Barbara J. Bond ◽  
James R. Ehleringer
Keyword(s):  
United States ◽  
Oxygen Isotope ◽  
Tree Ring ◽  
Isotope Ratios ◽  
Oxygen Isotope Ratios ◽  
Carbon And Oxygen Isotope ◽  
Tree Ring Cellulose

Hadrosaurid migration: inferences based on stable isotope comparisons among Late Cretaceous dinosaur localities

Paleobiology ◽  
2009 ◽  
Vol 35 (2) ◽  
pp. 270-288 ◽  
Author(s):  
Henry C. Fricke ◽  
Raymond R. Rogers ◽  
Terry A. Gates
Keyword(s):  
Oxygen Isotope ◽  
Late Cretaceous ◽  
Tooth Enamel ◽  
Isotope Ratios ◽  
Isotopic Signatures ◽  
Oxygen Isotope Ratios ◽  
Drinking Waters ◽  
Carbon And Oxygen Isotope ◽  
Western Interior Basin ◽  
Major Alteration

Stable carbon and oxygen isotope ratios were measured for carbonate in samples of hadrosaurid tooth enamel and dentine, and gar scale ganoine and dentine from five geologically “contemporaneous“ (two-million-year resolution) and geographically distant late Campanian formations (Two Medicine, Dinosaur Park, Judith River, Kaiparowits, and Fruitland) in the Western Interior Basin. In all cases, isotopic offsets were observed between enamel and dentine from the same teeth, with dentine being characterized by higher and more variable carbon and oxygen isotope ratios. Isotopic offsets were also observed between gar ganoine and hadrosaur enamel in all sites analyzed. Both of these observations indicate that diagenetic overprinting of enamel isotope ratios did not entirely obfuscate primary signals. Decreases in carbon and oxygen isotope ratios were observed in hadrosaur enamel from east to west, and overlap in isotope ratios occurred only between two of the sampled sites (Dinosaur Park and Judith River Formations).The lack of isotopic overlap for enamel among localities could be due to diagenetic resetting of isotope ratios such that they reflect local groundwater effects rather than primary biogenic inputs. However, the large range in carbon isotope ratios, the consistent taxonomic offsets for enamel/ganoine data, and comparisons of enamel-dentine data from the same teeth all suggest that diagenesis is not the lone driver of the signal. In the absence of major alteration, the mostly likely explanation for the isotopic patterns observed is that hadrosaurids from the targeted formations were eating plants and drinking waters with distinct isotopic ratios. One implication of this reconstruction is that hadrosaurids in the Late Cretaceous of the Western Interior did not migrate to an extent that would obscure local isotopic signatures.

Stratigraphic variations in carbon and oxygen isotopes in the dolostone of the Carswell Formation (Proterozoic) of northern Saskatchewan

1989 ◽  
Vol 26 (11) ◽  
pp. 2318-2326 ◽  
Author(s):  
P. I. Abell ◽  
J. McClory ◽  
H. E. Hendry ◽  
K. L. Wheatley
Keyword(s):  
Oxygen Isotope ◽  
Isotope Ratios ◽  
Drill Hole ◽  
Carbon And Oxygen Isotopes ◽  
Oxygen Isotope Ratios ◽  
Nearshore Environments ◽  
Carbon And Oxygen Isotope ◽  
Isotopic Analyses ◽  
Northern Saskatchewan ◽  
Lowermost Part

Petrographic and stable isotopic analyses of stromatolitic sediments deposited in nearshore environments provides us with some of the best information available on ancient environments. Diamond drill hole CAR 58 penetrated 110 m of sediments in the lowermost part of the Proterozoic (probably Helikian age) Carswell Formation of northern Saskatchewan and gave us such an opportunity. The rocks are mainly dolostone and include, in descending order of abundance, cyanobacterial laminites, stromatolites, dolomicrites, dolorudites, breccias, and oolites. Stromatolites and Cyanobacterial laminites increase in abundance up-section, and deposition is interpreted as having taken place in conditions of increasingly restricted water circulation through time. The carbon isotope ratios vary from about −0.5 to −1.5‰ (Pee Dee Belemnite (PDB)) in the section except near the base where they assume values near −2.5‰. The oxygen isotope ratios (vs. PDB) increase from about −9.3‰ at the base to −7‰ at the top, with anomolously high values, more positive than −7‰, at two positions in the sequence. Original depositional structures and textures are still visible in most of the rocks, but gypsum has been replaced by dolomite, there has been some silicification, and original features have been obliterated by dolomite rhombs in a few samples. The upward trend to less-negative values of the oxygen isotope ratios is interpreted in terms of changing depositional environment involving a deepening but more protected basin, with increased evaporational concentration of the heavier isotope. Scatter diagrams of carbon and oxygen isotope ratios place the Carswell Formation dolomites close to the mainstream of other Proterozoic stromatolites but indicating some evaporative alterations during deposition.

Stable isotope evidence for changes in dietary niche partitioning among hadrosaurian and ceratopsian dinosaurs of the Hell Creek Formation, North Dakota

Paleobiology ◽  
2008 ◽  
Vol 34 (4) ◽  
pp. 534-552 ◽  
Author(s):  
Henry C. Fricke ◽  
Dean A. Pearson
Keyword(s):  
Stable Isotope ◽  
Oxygen Isotope ◽  
Tooth Enamel ◽  
Habitat Preferences ◽  
Niche Partitioning ◽  
Isotope Ratios ◽  
Oxygen Isotope Ratios ◽  
Carbon And Oxygen Isotope ◽  
Dietary Niche ◽  
Ceratopsian Dinosaurs

Questions related to dinosaur behavior can be difficult to answer conclusively by using morphological studies alone. As a complement to these approaches, carbon and oxygen isotope ratios of tooth enamel can provide insight into habitat and dietary preferences of herbivorous dinosaurs. This approach is based on the isotopic variability in plant material and in surface waters of the past, which is in turn reflected by carbon and oxygen isotope ratios of animals that ingested the organic matter or drank the water. Thus, it has the potential to identify and characterize dietary and habitat preferences for coexisting taxa.In this study, stable isotope ratios from coexisting hadrosaurian and ceratopsian dinosaurs of the Hell Creek Formation of North Dakota are compared for four different stratigraphic levels. Isotopic offsets between tooth enamel and tooth dentine, as well as taxonomic differences in means and in patterns of isotopic data among taxa, indicate that primary paleoecological information is preserved. The existence of taxonomic offsets also provides the first direct evidence for dietary niche partitioning among these herbivorous dinosaur taxa. Of particular interest is the observation that the nature of this partitioning changes over time: for some localities ceratopsian dinosaurs have higher carbon and oxygen isotope ratios than hadrosaurs, indicating a preference for plants living in open settings near the coast, whereas for other localities isotope ratios are lower, indicating a preference for plants in the understory of forests. In most cases the isotope ratios among hadrosaurs are similar and are interpreted to represent a dietary preference for plants of the forest canopy. The inferred differences in ceratopsian behavior are suggested to represent a change in vegetation cover and hence habitat availability in response to sea level change or to the position of river distributaries. Given our current lack of taxonomic resolution, it is not possible to determine if dietary and habitat preferences inferred from stable isotope data are associated with single, or multiple, species of hadrosaurian/ceratopsian dinosaurs.

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