Now showing items 31-40 of 50
Indirect crustal contamination: evidence from isotopic and chemical disequilibria in minerals from alkali basalts and nephelinites from northern Tanzania
(Springer-Verlag; Springer-Verlag Berlin Heidelberg, 1996-11)
Alkali basalts and nephelinites from the volcanic province of northern Tanzania contain pyroxene and nepheline that show evidence for chemical and/or isotopic disequilibria with their host magmas. Olivine, pyroxene, ...
Petrology, isotope characteristics, and K-Ar ages of the Maranhão, northern Brazil, Mesozoic basalt province
(Springer-Verlag, 1990-04)
Northern Brazil contains remnants of Mesozoic flood basalts and hypabyssal rocks that were apparently emplaced during tectonism related to opening of the Atlantic Ocean. Analyses and new K-Ar ages reveal that this ∼700x250 ...
Mobility and fractionation of rare earth elements in argillaceous sediments: Implications for dating diagenesis and low-grade metamorphism
(Elsevier, 1994-01)
We report Sm-Nd and Rb-Sr data for the fine fractions of Lower Paleozoic argillaceous rocks from Wales, UK and New York, USA, spanning the range of low-grade metamorphic conditions from the diagenetic zone (zeolite facies) ...
[delta]18O values, 87Sr/86Sr and Sr/Mg ratios of Late Devonian abiotic marine calcite: Implications for the composition of ancient seawater
(Elsevier, 1991-07)
Late Devonian (Frasnian) abiotic marine calcite has been microsampled and analyzed for 87Sr/86Sr ratios, [delta]18O and [delta]13C values, and minor element concentrations. Portions of marine cement crystals from the Alberta ...
Origin and evolution of formation waters, Alberta Basin, Western Canada Sedimentary Basin. II. Isotope systematics and water mixing
(Elsevier, 1990)
Isotopic measurements (Sr, O, D) on formation waters from the Alberta Basin have been made, covering a stratigraphic range from Devonian to Upper Cretaceous. These measurements, combined with chemical compositional trends, ...
Variability of early diagenesis in lake sediments: Evidence from the sedimentary geolipid record in an isolated tarn
(Elsevier, 1994-02-10)
A 0.5-m-long core of sediment from Coburn Mountain Pond, Maine, U.S.A., has provided a virtually undisturbed and continuous record of sediment deposition for the last 200 yr in this small, essentially pristine tarn. Organic ...
Heat capacities of Fe 2 O 3 -bearing silicate liquids
(Springer-Verlag, 1992-04)
Direct measurements of liquid heat capacity, using a Setaram HT1500 calorimeter in step-scanning mode, have been made in air on six compositions in the Na 2 O-FeO-Fe 2 O 3 -SiO 2 system, two in the CaO-FeO-Fe 2 O 3 -SiO 2 ...
Sulfidation of organic matter associated with gold mineralization, Pueblo viejo, Dominican republic
(Elsevier, 1990)
The Pueblo Viejo district is one of the largest producers of precious metals in the world, yielding more than 11,000 kg of Au annually. Gold mineralization at Pueblo Viejo is hosted in spilite, and coarse clastic and finely ...
Global comparisons of organic matter in sediments across the Cretaceous/Tertiary boundary
(Elsevier, 1990)
The Cretaceous/Tertiary (K/T) boundary is marked by extensive changes in the sedimentary fossil record of continental and marine life. Organic matter in sediments from above and below the K/T boundary has been studied to ...