Mono- and bicyclic alkanes and diamondoid hydrocarbons in the Cretaceous/Tertiary boundary sediments at Kawaruppu, Hokkaido, Japan.

Abstract

Sixty-two mono-and 4 bicyclic alkanes, and 11 diamondoid hydrocarbons were detected in the Cretaceous-Tertiary (K/T) boundary sediments at Kawaruppu, Hokkaido, Japan. The monocyclic alkanes included series of n-alkylcyclohexanes, methyl-n-alkylcyclohexanes and n-alkylcyclopentanes, and other alkylcyclohexanes. The bicyclic alkanes included bicyclo[3.3.1]nonane, trans-decalin, and methyldecalins. The diamondoid hydrocarbons included adamantane, and methyl-and dimethyladamantanes, and diamantane and methyldiamantanes. These mono-and bicyclic alkanes were detected at a level of 0.001-0.1 nmol g -1 and the diamondoid hydrocarbons were at the same or one order magnitude less than those of the cyclic alkanes. Concentrations of all cyclic alkanes within the K/T boundary claystone were markedly small compared to those in the sediments above and below the claystone. The molecular distributions of nalkylcyclohexanes, methyl-n-alkylcyclohexanes and n-alkylcyclopentanes were relatively smooth within the claystone. On the other hand, those of n-alkylcyclohexanes and methyl-n-alkylcyclohexanes showed predominances from C 15 to C 18 and those of n-alkylcyclopentanes showed even carbon number predominances from C 16 to C 22 in the sediments above and below the boundary claystone. These characteristic features in concentration and molecular distribution within the boundary claystone are likely related to the large biomass extinction event at the end of the Cretaceous. Compositions of compounds among trimethylcyclohexanes, methylethylcyclohexanes, decalins, methyladamantanes, and methyldiamantanes were roughly constant over sedimentary sequence. This indicated that diagenetic effect to these compounds had been nearly constant over the sedimentary sequence.

Chemical and carbon isotopic evolution of hydrocarbons during prograde metamorphism from 100°C to 550°C: Case study in the Liassic black shale formation of Central Swiss Alps

“…The metamorphic samples have distinct n-alkylcyclopentane distributions with predominance of C 14 , C 16 , and to a lesser extend of the C 18 homologues. A similar n-alkylcyclopentane distribution was observed in the Cretaceous/Tertiary boundary sediments at Kawaruppu, Japan (Shimoyama and Yabuta, 2002). Comparison of the relative proportion of these n-alkylcyclopentanes (m/z 68 -69) vs. n-alkanes (m/z 70 -71) shows an increase of the n-alkylcyclopentanes at higher thermal stress.…”

Diamondoid Molecules

“…A full scan total ion chromatogram (TIC) of the sample is turned around from 100 m/z to 1000 m/z using molecular fragmentation spectrums (like Figure 14 for adamantane). With the availability of standard molecular fragmentation spectrums of diamondoids (like Figure 14 for adamantane) [81,82] diamondoids are identified in the sample.…”

High-pressure phase of natural fullerene C60 in iridium-rich Cretaceous–Tertiary boundary layers of Deccan intertrappean deposits, Anjar, Kutch, India

“…/j.gca.2007 Flaxbourne River (New Zealand). The presence of polycyclic-hydrocarbons, mono-and bicyclic alkanes, adamantine, diamantane, and methyldiamantanes in the KTB sediments at Kawaruppu was reported by Mita and Shimoyama (1999) and Shimoyama and Yabuta (2002). They attributed the concentration and molecular distribution to the large biomass extinction event at the end of the Cretaceous.…”

“…Absorption spectra of the soluble, as well as insoluble, carbon-extract from sample J in the 300-800 nm region. Yabuta, 2002). About 26 polycyclic aromatic hydrocarbons from naphthalene to coronene were reported from the KTB sediments at Kawaruppu, Hokkaido, Japan, indicating a possible combustion origin for these hydrocarbons in KTB clays (Shimoyama and Yabuta, 2002).…”