The redox-sensitive geochemical behavior of uranium permits the use of Th/U ratios as a geochemical proxy for the oxidation state of the atmosphere and oceans during sedimentary processes. Due to the effects of post-depositional uranium mobility on Th/U ratios during events involving oxygenated fluids, direct measurements of Th/U ratios are often misleading, but the whole rock Pb isotope compos...

Red clayey paleosols that are chiefly the product of aerosolic dust deposition are interbedded in the Quaternary carbonate formations of the Bermuda oceanic island system. These paleosols provide a basis for reconstructing Quaternary atmospheric circulation patterns in the northwestern Atlantic. Geochemical analyses were performed on representative paleosol samples to identify their parent dust...

A detailed geochemical study and a sequence stratigraphic interpretation have been conducted on a sedimentary sequence of the Upper Cretaceous La Luna Formation, in a section outcropping in the eastern ̄ank of the Middle Magdalena Basin (MMB), Colombia. The goals were to evaluate geochemical variability related to lithofacies and organic facies changes, characterize depositional environment and...

[1] Although most Central American magmas have a typical arc geochemical signature, magmas in southern Central America (central Costa Rica and Panama) have isotopic and trace element compositions with an ocean island basalt (OIB) affinity, similar to the Galapagos-OIB lavas (e.g., Ba/La < 40, La/Yb > 10, Pb/Pb > 18.8). Our new data for Costa Rica suggest that this signature, unusual for a conve...

[1] The temporal geochemical variations defined by lavas erupted throughout the growth of a single volcano provide important information for understanding how the Hawaiian plume works. The Hawaii Scientific Drilling Project (HSDP) sampled the shield of Mauna Kea volcano to a depth of 3100 meters below sea level during Phase 2 of the HSDP. Incompatible element abundance ratios, such as La/Yb, Sm...

Geochemical signals of bulk sedimentary organic matter from three cores from Lake Tanganyika provided information about both internal processes and terrestrial inputs to the lake. Indications of land use change were detected in the geochemical records of the watersheds, and the timing of these changes was consistent with historical records of population demographics. While C:N ratios suggested ...

Abstract The study is aimed to apply the Pb isotope fingerprinting technique for tracing pollution of urban surface deposited sediment (USDS). USDS reflect changes in geochemical conditions occurring environment. samples were collected residential areas with multistory buildings Russian cities: Magnitogorsk, Nizhny Tagil, Tyumen, Ufa, and Chelyabinsk. Elements concentrations stable isotopic rat...

Exhaust particulate from compression ignition (CI) engines running on engine and chassis dynamometers was studied. Particulate dichloromethane extracts were qualitatively and quantitatively analyzed for polycyclic aromatic hydrocarbons (PAHs) and biomarkers by gas chromatography with flame ionization detector (GC-FID) and gas chromatography-mass spectrometry (GC-MS). PAH group profiles were mad...

The geochemical and isotopic (strontium, boron, radium, oxygen, hydrogen) variations of geothermal waters from five different regions in Morocco were investigated in order to evaluate the sources of solutes and the mechanisms of water-rock interaction. During 2008 to 2010, twenty-two geothermal water samples were collected from the southern, central, and northern parts of Morocco. The water sam...