a detailed study of ostracoda changes against the stable isotopes of carbon and oxygen acrossthe cenomanian-turonian boundary mass extinction has been fully documented in one section, the south ofengland. this section comprises the uppermost cenomanian to lowermost turonian strata. the comparisonbetween the results obtained in this research and two rival models for the cenomanian-turonian bound...

pb-zn deposits in the kurdistan region, northern iraq, have occurred mainly as a stratabound and open-space filling ore bodies. they are hosted by dolostone and dolomitic-limestone of platform carbonates. the ore deposits at the studied dure and lefan areas are respectively hosted by kurra chine (upper triassic) and bekhme (upper cretaceous) formations. pyrite, sphalerite and galena are the maj...

a total of 40 samples from carbonates and 8 samples from silicate rocks were analyzed from the sangan iron skarn deposit to examine behavior of the oxygen and carbon isotopes. the higher values of ?18o are from metamorphic calcite and dolomite and lower ones are from granitic rocks. although the ?18o and ?13c values of calcite and dolomite in marble yield the highest values in the sangan deposi...

a total of 40 samples from carbonates and 8 samples from silicate rocks were analyzed from the sangan iron skarn deposit to examine behavior of the oxygen and carbon isotopes. the higher values of ?18o are from metamorphic calcite and dolomite and lower ones are from granitic rocks. although the ?18o and ?13c values of calcite and dolomite in marble yield the highest values in the sangan deposi...

The application of stable isotope analysis (SIA) has become a standard scientific approach in Agricultural and Ecological researches and, more in general, in several disciplines such as biology, botany, zoology, organic chemistry, climatology, and nutrition. The main objectives of this paper are (1) to provide a simple definition of stable isotopes and (2) to illustrate analytical measurement m...

the isotopic documents of lake deposition are suitable potential means for studyingthe intercontinental, environmental and climatic conditions. in order to study theenvironmental and climatic conditions of parishan area in fars province in holocene, a corewas taken with the length of 2m from the parishan lake sediment. from this core, kernel timeseries was provided from documents of carbon and ...

Stable isotopes of carbon and nitrogen are increasingly used in marine ecosystems, for ecological and environmental studies. Here, we examine some applications of stable isotopes as ecological integrators or tracers in seagrass ecosystem studies. We focus on both the use of natural isotope abundance as food web integrators or environmental tracers and on the use of stable isotopes as experiment...

the upper cretaceous carbonate sequence of ab-deraz formation is well exposed in the kopet- dagh basin. this formation comprises marly limestone and three chalky limestone units. chalky limestone of ab-deraz formation is mainly composed of calcareous dinoflagellate (pithonellid calcispher), cocolithofore and planktonic foraminifera. carbon and oxygen stable isotopes analysis of the third chalky...

Introduction Direct measurement of de novo lipogenesis has not previously been possible in humans. We measured de novo hepatic lipogenesis in normal men by means of stable isotopes and by combining the acetylated-xenobiotic probe technique with mass isotopomer analysis of secreted very low density lipoproteinfatty acids (VLDL-FA). Sulfamethoxazole (SMX) was administered with ['3Clacetate during...

We tested the competing hypotheses that (1) nitrogen discrimination in mammals and birds increases with dietary nitrogen concentration or decreasing C:N ratios and, therefore, discrimination will increase with trophic level as carnivores ingest more protein than herbivores and omnivores or (2) nitrogen discrimination increases as dietary protein quality decreases and, therefore, discrimination ...