Geochemistry of the Cretaceous-Tertiary transition boundary at Blake Nose (NW Atlantic): Cosmogenic Ni

The Cretaceous-Tertiary, (KT) boundary transition at the Blake Nose Plateau recovered by ODP Lea 171B (site 1049, hole A. core 17X. section 2) contains an ejecta bed (thickness ca. 17 cm) marking a late Cretaceous asteroid impact. The nature and geochemical composition of this bed imply that it originated mainly from the target rocks of the Chicxulub impact site (Yucatan Peninsula, Mexico). the site of the presumed asteroid impact. The ejecta bed of hole 1049A contains relatively high concentrations of Ni (up to 165 ppm) within the carbonate fraction. It is reasoned that this enhancement represents a sudden and rapid airfall of high cosmogenic Ni into he Blake Nose Basin. The source of the metal was the Chicxulub impacting (carbonaceous) chondrite. It is suggested that many calcareous planktons in the KT ocean surface water of the Blake Nose Plateau were probably vulnerable to the high influx of superacid rainfall and associated toxic metals (e.g., Ni) created by the impact

Electron spin resonance studies on titanium(III) chloride in aqueous 2-methyl- 2-butanol (z-amyl alcohol)

1039-1044On addition of small amounts of water (1% to 2%, v/v) to TiCl3 (0.02 M, pH 1.4 to 1.8) partially dissolved in t-amyl alcohol, an electron spin resonance signal (g0 = 1.9589 ± 0.0002) with well-resolved superhyperfine structure due to water protons is observed (the coupling constant equals 0.187 ± 0.003 mT). Confirmation of splitting to be due to water hydrogens has been obtained by using D2O in equivalent experiments. Aqueous solutions of Ti2(SO4)3, TiBr3 or TiI3 (0.01 M to 1.0 M, pH 0.8 to 1.8) saturated with t-amyl alcohol (ca. 5%, v/v) give no electron spin resonance signal. Addition of NaCl or LiCl (1.0 M) to these solutions produces a signal identical in hyperfine pattern and-close in the value of g factor (1.9580±0.0002) to that for TiCl3 solution. It is proposed that there are axial alkoxide and chloride ions and four equatorial water molecules in the first coordination sphere of this ESR-active Ti(III) complex ion. Approximate spin concentration measurements, made employing deuterated samples, indicate that maximum ESR signal intensity (at ca. 2% added water) represents only 15 ± 5% of the nominal Ti(III) that is present

Vanadium of petroleum asphaltenes and source kerogens (La Luna Formation, Venezuela): isotopic study and origin

High-resolution mass spectrometry indicates that the isotopic abundance of (50)vanadium (V) of the Late Cretaceous La Luna petroleum asphaltenes and related source kerogens of marine origin (both highly enriched with V GT 2000 ppm) is higher by about 3.5% than that of inorganic source (VOSO4.5H(2)O, Merck). Similar results are obtained with the isotopic analysis of the asphaltenes (containing high V) extracted from the floating asphalts (Dead Sea, Israel). We propose that the difference in the V-50/V-51 values between the La Luna petroleum asphaltenes/source kerogens and inorganic source can be best ascribed to the biological processing of the seawater V. The fact that the isotopic composition of V of the vary over a very narrow range (2.46-2.52) suggests an essentially same (or similar) and fixed (micro)biological source of V. Isotopic analysis was also extended to the methanol-soluble fractions of the La Luna asphaltic petroleums (DM-119/-120/-124) highly enriched with extractable (alkyl) vanadyl-porphyrins (VO2+-P). This analysis shows that the isotopic abundance of V-50 for the methanol-soluble fractions agrees (within the limits of experimental error) with those of the asphaltenes/kerogens. (C) 2002 Elsevier Science Ltd. All rights reserved

Copper and copper(II) porphyrins of the Cretaceous-Tertiary boundary at Stevns Klint (Denmark)

High levels of copper(II) (Cu2+) were found with the major part ( GT 90%) of the total Cu located in the smectite (Cu: 175 ppm) and kerogen (Cu: up to 1000 ppm) of the basal black marl of the Cretaceous-Tertiary (KT) boundary informal type sedimentary rock: the Fish Clay at Stevns Klint, Denmark. Anomalous abundance (4000 ppm) of the kerogen Cu2+-porphyrins in this marl was detected by electron spin resonance. A model is proposed in which the enormous acid rains (caused by the KT asteroid impact) washed out the humics (already enriched with Cu2+/Cu2+-porphyrins) of the top horizon of the nearby oxic soil into the Fish Clay Basin during the KT event. (C) 2000 Elsevier Science B.V. All rights reserved

Estimation of vanadyl porphyrin concentration in sedimentary kerogens and asphaltenes

We describe a new, rapid method for determining the concentration of vanadyl porphyrins (VO2+-P) associated with the kerogen of bituminous sedimentary rocks using electron spin resonance (ESR). The method is simple, straightforward and inexpensive. Several concentrations of a vanadyl (VO2+) standard dissolved in glycerol-lignite mixture were prepared. The VO2+ concentrations ranged from 100 to 1000 ppm. The anisotropic ESR spectra of both the standards and kerogen samples were recorded at room temperature and the integrated areas of the pre-selected ESR line (attributed to nuclear spin m(t) = -5/2) were computed. The concentrations of VO2+ found in the kerogen samples were calculated using the relative ratio of the integrated areas for the standards and the kerogen samples. The VO2+-P concentrations of the kerogen materials were then calculated using 350 as the mean molecular weight of these species. Quantitative determination of VO2+-P in the kerogen fractions in the range of 800-8000 ppm and higher is feasible by the method reported. The method of analysis was also extended to the asphaltene samples (enriched with VO2+-P) and a coal sample containing non-porphyrin VO2+ associated with its organic fraction. (C) 2000 Elsevier Science Ltd. All rights reserved

Classification of the asphalts and their source rock from the Dead Sea Basin (Israel): the asphaltene/kerogen vanadyl porphyrins

The asphaltenes of the asphalts from the Dead Sea Basin were examined for the occurrence of vanadyl porphyrins. These examinations demonstrate that the asphalts fall into two broad class types: one which exhibits a relatively high vanadyl porphyrins content ( GT 300ppm), and the other characterized with no vanadyl porphyrins ( LT 10 ppm). It is concluded that these asphalts belong to two distinct types and have separate origins. The kerogens isolated from the petroleum-source rock of the Dead Sea Basin were also analyzed. Two genetic types of kerogen appeared to exist: a marine one highly enriched with these pigments and a terrestrial one with no vanadyl porphyrins. For comparison, the asphaltenes of typical asphaltic crude oils from Western Venezuela and kerogen from their La Luna source rock were also examined. Previous detailed geochemical studies indicated that the La Luna kerogen is derived from marine organic matter source. These materials have higher concentrations of vanadyl porphyrins than the Dead Sea asphaltenes and kerogens are enriched with these compounds. Our results strengthen the potential of vanadyl porphyrins of both petroleum asphaltenes and source-rock kerogen for use in genetic and correlation studies. (C) 1998 Elsevier Science Ltd. AII rights reserved

Vanadyl porphyrins in sedimentary kerogens/asphaltenes: Estimation of the concentration

A new, rapid method for determining the concentration of vanadyl porphyrins (VO2+-P) associated with the kerogen of bituminous sedimentary rocks, using electron spin resonance (ESR) is described. The method is simple, straightforward and inexpensive. Several concentrations of a vanadyl (VO2+) standard dissolved in glycerol/lignite mixture were prepared. The VO2+ concentrations ranged from 100-1000 ppm. The anisotropic ESR spectra of both the standards and kerogen samples were recorded at room temperature and the integrated areas of the pre-selected ESR line (attributed to nuclear spin m(I) = -5/2) were computed. The concentrations of VO2+ found in the kerogen samples were calculated using the relative ratio of the integrated areas for the standards and the kerogen samples. The VO2+-P concentrations of the kerogen materials were then calculated using 450 as the mean molecular weight of these species. The quantitative determination of VO2+-P in the kerogen fractions in the range 800 ppm and 8000 ppm and higher is feasible by the method reported. The method of analysis was also extended to asphaltene samples (enriched with VO2+-P) and a coal sample containing associated with its organic fraction

Cretaceous-Tertiary boundary layer at Stevns Klint (Denmark): copper and copper(II) porphyrins

High concentrations (up to 4000 ppm) of copper(rr) porphyrins have been detected in the kerogen of the Cretaceous/Tertiary (KT) boundary informal type sediment, the Fish Clay, at Stevns Klint, Denmark. These pigments have also been found in the Danish KT sediment at Nye Klov, which is about 300 kin away from Stevns Klint. However, copper(II) porphyrins cannot be detected in the Danich boundary rock of the Dania site, which is separated from Stevns Klint by about 200 kin. It is proposed that the kerogen copper(II) porphyrins are derived from humic materials of terrestrial (peat/soil) sources already enriched with these compounds, which were redeposited in the Danish KT boundary Basin. In addition, our results show that the kerogen copper(II) porphyrins are present, for comparison, in the Permian Kupferschiefer shale from Poland. The amounts are comparable to those in the Fish Clay kerogen. To our opinion, the same processes responsible for the kerogen copper(II) porphyrin enrichment have occurred in the Stevns Klint KT boundary sediment and in the Kupferschiefer

Classification of the asphalts and their source rock from the Dead Sea Basin (Israel): the asphaltene/kerogen vanadyl porphyrins

The asphaltenes of the asphalts from the Dead Sea Basin were examined for the presence of vanadyl porphyrins. These examinations demonstrated that the asphalts fall into two broad class types, one having a relatively high vanadyl prophyrins content ( GT 300 ppm) and the other characterized by no vanadyl porphyrins ( LT 10 ppm). It is concluded that these asphalts belong to two generic types and have separate origins. The kerogens isolated from the petroleum-source rock of the Dead Sea Basin were also analyzed. Two genetic types of kerogen appeared to exist, a marine one highly enriched with these pigments and a terrestrial one with no vanadyl porphyrins. For comparison, the asphaltenes of typical asphaltic crude oils from Western Venezuela and kerogen from their La Luna source rock were also examined. Previous detailed geochemical studies indicated that La Luna kerogen is derived from marine organic matter source. These materials have higher concentrations of vanadyl porphyrins than the Dead Sea asphaltenes and the kerogens are enriched with these compounds. Our results strengthen the potential of vanadyl porphyrins of both petroleum asphaltenes and source-rock kerogen for use in genetic and correlation studies

Electron spin resonance study of the kerogen/asphaltene vanadyl porphyrins: air oxidation

Thermal behavior of vanadyl porphyrins was studied by electron spin resonance during heating of the kerogens isolated from the La Luna (Venezuela), Maganik(Montenegro) and Serpiano (Switzerland) bituminous rocks at 150 and 250 degreesC for 1 to 20 days in the presence of air. During the thermal treatment of the kerogens the vanadyl porphyrins resonance signals decrease monotonically and become quite small after six days of heating. Concomitantly, new vanadyl signals appear, and, at longer heating times, dominate the spectrum. It is suggested that the secondary vanadyl species must have been formed from vanadyl porphyrins. Similar conversion of vanadyl porphyrins are observed under the same experimental conditions for the asphaltenes extracted from the La Luna and Serpiano rocks, and the floating asphalt from the Dead Sea (Israel). A comparison of the spin-Hamiltonian parameters for vanadyl porphyrins and vanadyl compounds obtained during pyrolysis of the kerogens/asphaltenes suggests that these are of non-porphyrin type. For comparison, a study was conducted on the Western Kentucky No. 9 coal enriched with vanadium (up to 800 ppm) from six mines. All coal samples show only the presence of predominant vanadyl-non-porphyrin compounds similar to those generated through laboratory heating of the kerogens/asphaltenes in air. In addition, some samples also contain a minor amount of vanadyl porphyrins. (C) 2001 Elsevier Science Ltd. All rights reserved