Ken B. Anderson

The nature and fate of natural resins in the geosphere—II. Identification, classification and nomenclature of resinites

Abstract A classification scheme for resinites is proposed. Most resinites may be classified, on the basis of structural characteristics, into one of four classes. In order to exclude the effects of structural changes which reflect differences in the relative maturity of different samples, classifications are based on the structural character of the original resin from which the resinite was derived. In all samples characterized to date, this may be reasonably inferred from analytical data concerning the structure and composition of the individual sample. Class I resinites, which are by far the most abundant form of resinite in the geosphere, are derived from resins based primarily on polymers of labdatriene (diterpenoid) carboxylic acids, especially communic or ozic acids. Class II resinites are derived from resins based on polymers of sesquiterpenoid hydrocarbons, especially various isomers of cadinene. Class III resinites are natural polystyrenes. Class IV resinites are the least well characterized of the four resinite classes defined, but appear to be largely non-polymeric materials, dominated by sesquiterpenoids based on the cedrane carbon skeleton. Resinites belonging to Class I are further subdivided into three sub-classes on the basis of details of their composition. Class Ia resinites, which include succinite and related “Baltic ambers”, are derived from resins based primarily on communic acid and incorporate significant amounts of succinic acid into their macromolecular structure. Class Ib resinites are also derived from resins based primarily on communic acid, but do not contain succinic acid. Class Ic resinites are derived from resins based primarily on labdatrienoic acids of the enantio series, especially ozic and/or zanzibaric acids. The structure, origin, and identification of resinites of each class are discussed. The effects of maturation on the structure of Class I resinites, and the consequences of these changes for the recognition and classification of this form of resinite are also briefly discussed.

Moving Geochemical Transactions forward as an open access journal

Geochemical Transactions, the first online-only journal in geochemistry and environmental chemistry, is now the first major open access journal in this subject area. All issues of Geochemical Transactions, including the back content, will be fully and permanently available online to all, without a subscription charge. Copyright of all future articles will be retained by the authors. Geochemical Transactions remains the official journal of the Division of Geochemistry of the American Chemical Society. The generous support of the Division has made it possible to make the back content available without a subscription charge.

The nature and fate of natural resins in the geosphere—iii. re-evaluation of the structure and composition of highgate copalite and glessite

Abstract The results of GC-MS, Py-GC-MS and spectroscopic (solid state 13 C NMR) studies of the structure and composition of two resinites, viz. Highgate Copalite and Glessite , which have been previously described as “fossil elemi” are described. GC-MS analyses of Highgate Copalite establish that this resinite is composed of a simple mixture of diterpenoid resin acids and n -alkyl materials. Based on comparison of these data with similar data obtained by analysis of modern rosin, it is concluded that this resinite is most probably derived from the resin of an undetermined species of pine. In order to accomodate resinites of this general character, it is proposed that an additional class, viz: Class V, be added to the classification system for resinites which we have previously proposed (Anderson et al. , 1992). Py-GC-MS analysis of Glessite establish that this material is a typical Class Ia resinite closely related to Succinite (“normal” or “typical” Baltic Amber). It is concluded that the previously assigned structural character of these two resinites is open to question.

The nature and fate of natural resins in the geosphere—IV. Middle and Upper Cretaceous amber from the Taimyr Peninsula, Siberia—evidence for a new form of polylabdanoid of resinite and revision of the classification of Class I resinites☆

Abstract Analysis of three amber (resinite) samples collected from Middle and Upper Cretaceous sediments in the Taimyr Peninsula, Siberia, indicates that these materials are based on copolymers of biformene (I) and communol (II). These resinites represent a previously undescribed form of Class I (polylabdanoid) resinite. Definitions of the sub-classes of Class I resinites have been revised (generalized) to recognize the general relation between these samples and other Class Ib resinites, and to facilitate classification of polylabdanoid resinites which do not necessarily incorporate communic (or ozic) acids.

Cretaceous African life captured in amber.

Amber is of great paleontological importance because it preserves a diverse array of organisms and associated remains from different habitats in and close to the amber-producing forests. Therefore, the discovery of amber inclusions is important not only for tracing the evolutionary history of lineages with otherwise poor fossil records, but also for elucidating the composition, diversity, and ecology of terrestrial paleoecosystems. Here, we report a unique find of African amber with inclusions, from the Cretaceous of Ethiopia. Ancient arthropods belonging to the ants, wasps, thrips, zorapterans, and spiders are the earliest African records of these ecologically important groups and constitute significant discoveries providing insight into the temporal and geographical origins of these lineages. Together with diverse microscopic inclusions, these findings reveal the interactions of plants, fungi and arthropods during an epoch of major change in terrestrial ecosystems, which was caused by the initial radiation of the angiosperms. Because of its age, paleogeographic location and the exceptional preservation of the inclusions, this fossil resin broadens our understanding of the ecology of Cretaceous woodlands.

Low temperature steam reforming of methanol over layered double hydroxide-derived catalysts.

The catalytic production of hydrogen by steam reforming of methanol (SRM) has been carried out over Mg/Al, Cu/Al, Co/Al, and Ni/Al layered double hydroxides (LDHs). The catalytic reactions were performed at temperatures of 150-400 C and atmospheric pressure. The most efficient catalyst was the Cu/Al LDH, which became active at {approx}230 C, with concomitant H{sub 2} production. The Ni/Al and Co/Al LDHs were also active in SRM, however, the activation temperature was significantly higher (315-320 C). No catalytic activity was observed for the Mg/Al LDH. Significant LDH decomposition occurred during the catalytic reactions. The reducibility of the divalent cations present in the LDH was a crucial parameter in determining the steam reforming activity of the catalysts. Pre-activation of the Cu/Al LDH by calcination in air (400 C), followed by reduction in dilute H2, did not significantly change the catalytic activity. The onset of H2 production was slightly lower for the pre-activated versus as-prepared Cu/Al LDH ({approx}218 C), also the CH{sub 3}OH conversion was 5-10% lower.

The nature and fate of natural resins in the geosphere. IX Structure and maturation similarities of soluble and insoluble polylabdanoids isolated from Tertiary Class I resinites.

Abstract Soluble polylabdanoids were isolated from five Tertiary Class I resinites by sequential extraction and were characterized by 13 C and 1 H NMR spectroscopy and Py–GC–MS. The structure and maturation characteristics of soluble extracts were strikingly similar to those observed for polylabdanoids in the native resinite. Soluble and insoluble materials undergo parallel geotransformation processes similar to those observed previously, including (i) exomethylene and total olefinic carbon depletion, (ii) double bond redistribution as indicated by ∑C14/∑C15 pyrolysis product ratios and (iii) A-ring defunctionalization. Resonances at 138 and 127 ppm in 13 C NMR spectra were shown to be those of aromatic and olefinic structures in mature samples, indicating that double bond content had been overestimated in the past. Proton NMR analyses have revealed several structural features previously unobserved. Resonances at 5.3 ppm of mature polymers were assigned to trisubstituted olefins in cyclized/cross-linked polylabdanoids. Further evidence in support of this pathway is derived from 13 C NMR spectra, from which an increase in aliphatic carbon content paralleling the loss of olefinic structures was observed.

Chemical signatures of fossilized resins and recent plant exudates.

Amber is one of the few gemstones based on an organic structure. Found over most of the world, it is the fossil form of sticky plant exudates called resins. Investigation of amber by modern analytical techniques provides structural information and insight into the identity of the ancient plants that produced the source resin. Mass spectrometric analysis of materials separated by gas chromatography has identified specific compounds that are the basis of a reliable classification of the different types of amber. NMR spectroscopy of bulk, solid amber provides a complementary classification. NMR spectroscopy also can be used to characterize modern resins as well as other types of plant exudates such as gums, gum resins, and kinos, which strongly resemble resins in appearance but have very different molecular constitutions.

Analysis of Fossil Resins from Axel Heiberg Island, Canadian Arctic

Ambers are well known and abundant in terrestrial sediments all over the world; however, due largely to the absence of definite morphological characteristics, the precise botanical origin of most amber samples, are at best, often a matter of speculation. This has severely restricted the usefulness of amber in paleobotanical and paleoecological interpretations. The molecular composition and structural characteristics of fossil resins however, may preserve evidence of their botanical origin, which could be of great value in both geochemical, paleobotanical, and paleoenvironmental studies. The remains of a number of exceptionally well-preserved Taxodiaceae-dominated swamp-forest communities have been identified in the sediments of the middle Eocene (45 million years old) Buchanan Lake Formation of Axel Heiberg Island, Canadian Arctic Archipelago. The amber collected from these ancient in situ forests provides a unique opportunity to characterize these resins chemically and taxonomically. Resinite associated with Metasequoia, Pinus and Pseudolarix has been characterized using Pyrolysis-Gas Chromatography-Mass Spectrometry. This method provides a direct analysis of the molecular structure and composition of the resin. In several cases, both bled resin and cone-resin samples have been characterized. The results of these analyses are presented and discussed. The implications of these results for the botanical origins of other ambers represented in the fossil record (including succinite) will also be discussed.

Branched aliphatic alkanes with quaternary substituted carbon atoms in modern and ancient geologic samples

A pseudohomologous series of branched aliphatic alkanes with a quaternary substituted carbon atom (BAQCs, specifically 2,2-dimethylalkanes and 3,3- and 5,5-diethylalkanes) were identified in warm (65°C) deep-sea hydrothermal waters and Late Cretaceous black shales. 5,5-Diethylalkanes were also observed in modern and Holocene marine shelf sediments and in shales spanning the last 800 million years of the geological record. The carbon number distribution of BAQCs indicates a biological origin. These compounds were observed but not identified in previous studies of 2.0 billion- to 2.2 billion-year-old metasediments and were commonly misidentified in other sediment samples, indicating that BAQCs are widespread in the geological record. The source organisms of BAQCs are unknown, but their paleobiogeographic distribution suggests that they have an affinity for sulfides and might be nonphotosynthetic sulfide oxidizers.