Palynology

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Pine pollen under the microscope Palynologie-exemple.jpg
Pine pollen under the microscope
A late Silurian sporangium bearing trilete spores. Such spores provide the earliest evidence of life on land. Green: A spore tetrad. Blue: A spore bearing a trilete mark - the Y-shaped scar. The spores are about 30-35 mm across. Trilete spores.png
A late Silurian sporangium bearing trilete spores. Such spores provide the earliest evidence of life on land. Green: A spore tetrad. Blue: A spore bearing a trilete mark – the Y-shaped scar. The spores are about 30–35 μm across.

Palynology is the study of microorganisms and microscopic fragments of mega-organisms that are composed of acid-resistant organic material and occur in sediments, sedimentary rocks, and even some metasedimentary rocks. Palynomorphs are the microscopic, acid-resistant organic remains and debris produced by a wide variety of plants, animals, and Protista that have existed since the late Proterozoic. [2] [3]

Contents

It is the science that studies contemporary and fossil palynomorphs (paleopalynology), including pollen, spores, orbicules, dinocysts, acritarchs, chitinozoans and scolecodonts, together with particulate organic matter (POM) and kerogen found in sedimentary rocks and sediments. Palynology does not include diatoms, foraminiferans or other organisms with siliceous or calcareous tests. The name of the science and organisms is derived from the Greek Greek : παλύνω, translit.  palynō, "strew, sprinkle" and -logy ) or of "particles that are strewn". [3] [4]

Palynology is an interdisciplinary science that stands at the intersection of earth science (geology or geological science) and biological science (biology), particularly plant science (botany). Biostratigraphy, a branch of paleontology and paleobotany, involves fossil palynomorphs from the Precambrian to the Holocene for their usefulness in the relative dating and correlation of sedimentary strata. Palynology is also used to date and understand the evolution of many kinds of plants and animals. In paleoclimatology, fossil palynomorphs are studied for their usefulness in understanding ancient Earth history in terms of reconstructing paleoenvironments and paleoclimates. [3] [4]

Palynology is quite useful in disciplines such as Archeology, in honey production, and criminal and civil law. [3] [4] In archaeology, palynology is widely used to reconstruct ancient paleoenvironments and environmental shifts that significantly influenced past human societies and reconstruct the diet of prehistoric and historic humans. Melissopalynology, the study of pollen and other palynomorphs in honey, identifies the sources of pollen in terms of geographical location(s) and genera of plants. This not only provides important information on the ecology of honey bees, it also an important tool in discovering and policing the criminal adultriation and mislabeling of honey and its products. Forensic palynology uses palynomorphs as evidence in criminal and civil law to prove or disprove a physical link between objects, people, and places. [4] [5]

Palynomorphs

Palynomorphs are broadly defined as the study of organic remains, including microfossils, and microscopic fragments of mega-organisms that are composed of acid-resistant organic material and range in size between 5 and 500 micrometres. They are extracted from soils, sedimentary rocks and sediment cores, and other materials by a combination of physical (ultrasonic treatment and wet sieving) and chemical (acid digestion) procedures to remove the non-organic fraction. Palynomorphs may be composed of organic material such as chitin, pseudochitin and sporopollenin. [6]

Palynomorphs form a geological record of importance in determining the type of prehistoric life that existed at the time the sedimentary strata was laid down. As a result, these microfossils give important clues to the prevailing climatic conditions of the time. Their paleontological utility derives from an abundance numbering in millions of palynomorphs per gram in organic marine deposits, even when such deposits are generally not fossiliferous. Palynomorphs, however, generally have been destroyed in metamorphic or recrystallized rocks. [6]

Typical palynomorphs include dinoflagellate cysts, acritarchs, spores, pollen, plant tissue, fungi, scolecodonts (scleroprotein teeth, jaws, and associated features of polychaete annelid worms), arthropod organs (such as insect mouthparts), and chitinozoans. Palynomorph microscopic structures that are abundant in most sediments are resistant to routine pollen extraction. [6]

Palynofacies

A palynofacies is the complete assemblage of organic matter and palynomorphs in a fossil deposit. The term was introduced by the French geologist André Combaz  [ wikidata ] in 1964. Palynofacies studies are often linked to investigations of the organic geochemistry of sedimentary rocks. The study of the palynofacies of a sedimentary depositional environment can be used to learn about the depositional palaeoenvironments of sedimentary rocks in exploration geology, often in conjunction with palynological analysis and vitrinite reflectance. [7] [8] [9]

Palynofacies can be used in two ways:

History

Pollen core sampling, Fort Bragg, North Carolina Pollen core sampling.jpg
Pollen core sampling, Fort Bragg, North Carolina

Early history

The earliest reported observations of pollen under a microscope are likely to have been in the 1640s by the English botanist Nehemiah Grew, [10] who described pollen and the stamen, and concluded that pollen is required for sexual reproduction in flowering plants.

By the late 1870s, as optical microscopes improved and the principles of stratigraphy were worked out, Robert Kidston and P. Reinsch were able to examine the presence of fossil spores in the Devonian and Carboniferous coal seams and make comparisons between the living spores and the ancient fossil spores. [11] Early investigators include Christian Gottfried Ehrenberg (radiolarians, diatoms and dinoflagellate cysts), Gideon Mantell (desmids) and Henry Hopley White (dinoflagellate cysts).

1890s to 1940s

Quantitative analysis of pollen began with Lennart von Post's published work. [12] Although he published in the Swedish language, his methodology gained a wide audience through his lectures. In particular, his Kristiania lecture of 1916 was important in gaining a wider audience. [13] Because the early investigations were published in the Nordic languages (Scandinavian languages), the field of pollen analysis was confined to those countries. [14] The isolation ended with the German publication of Gunnar Erdtman's 1921 thesis. The methodology of pollen analysis became widespread throughout Europe and North America and revolutionized Quaternary vegetation and climate change research. [13] [15]

Earlier pollen researchers include Früh (1885), [16] who enumerated many common tree pollen types, and a considerable number of spores and herb pollen grains. There is a study of pollen samples taken from sediments of Swedish lakes by Trybom (1888); [17] pine and spruce pollen was found in such profusion that he considered them to be serviceable as "index fossils". Georg F. L. Sarauw studied fossil pollen of middle Pleistocene age (Cromerian) from the harbour of Copenhagen. [18] Lagerheim (in Witte 1905) and C. A.Weber (in H. A. Weber 1918) appear to be among the first to undertake 'percentage frequency' calculations.

1940s to 1989

The term palynology was introduced by Hyde and Williams in 1944, following correspondence with the Swedish geologist Ernst Antevs, in the pages of the Pollen Analysis Circular (one of the first journals devoted to pollen analysis, produced by Paul Sears in North America). Hyde and Williams chose palynology on the basis of the Greek words paluno meaning 'to sprinkle' and pale meaning 'dust' (and thus similar to the Latin word pollen). [19] The archive-based background to the adoption of the term palynology and to alternative names (e.g. paepalology, pollenology) has been exhaustively explored. [20] It has been argued there that the word gained general acceptance once used by the influential Swedish palynologist Gunnar Erdtman.

Pollen analysis in North America stemmed from Phyllis Draper, an MS student under Sears at the University of Oklahoma. During her time as a student, she developed the first pollen diagram from a sample that depicted the percentage of several species at different depths at Curtis Bog. This was the introduction of pollen analysis in North America; [21] pollen diagrams today still often remain in the same format with depth on the y-axis and abundances of species on the x-axis.

1990s to the 21st century

Pollen analysis advanced rapidly in this period due to advances in optics and computers. Much of the science was revised by Johannes Iversen and Knut Fægri in their textbook on the subject. [22]

Methods of studying palynomorphs

Chemical preparation

Chemical digestion follows a number of steps. [23] Initially the only chemical treatment used by researchers was treatment with potassium hydroxide (KOH) to remove humic substances; defloculation was accomplished through surface treatment or ultra-sonic treatment, although sonification may cause the pollen exine to rupture. [14] In 1924, the use of hydrofluoric acid (HF) to digest silicate minerals was introduced by Assarson and Granlund, greatly reducing the amount of time required to scan slides for palynomorphs. [24]

Palynological studies using peats presented a particular challenge because of the presence of well-preserved organic material, including fine rootlets, moss leaflets and organic litter. This was the last major challenge in the chemical preparation of materials for palynological study. Acetolysis was developed by Gunnar Erdtman and his brother to remove these fine cellulose materials by dissolving them. [25] In acetolysis the specimen is treated with acetic anhydride and sulfuric acid, dissolving cellulistic materials and thus providing better visibility for palynomorphs. [26]

Some steps of the chemical treatments require special care for safety reasons, in particular the use of HF which diffuses very fast through the skin and, causes severe chemical burns, and can be fatal. [27]

Another treatment includes kerosene flotation for chitinous materials.

Analysis

Once samples have been prepared chemically, they are mounted on microscope slides using silicon oil, glycerol or glycerol-jelly and examined using light microscopy or mounted on a stub for scanning electron microscopy.

Researchers will often study either modern samples from a number of unique sites within a given area, or samples from a single site with a record through time, such as samples obtained from peat or lake sediments. More recent studies have used the modern analog technique in which paleo-samples are compared to modern samples for which the parent vegetation is known. [28]

When the slides are observed under a microscope, the researcher counts the number of grains of each pollen taxon. This record is next used to produce a pollen diagram. These data can be used to detect anthropogenic effects, such as logging, [29] traditional patterns of land use [30] or long term changes in regional climate [31]

Applications

Palynology can be applied to problems in many scientific disciplines including geology, botany, paleontology, archaeology, pedology (soil study), and physical geography:

See also

Related Research Articles

<span class="mw-page-title-main">Forensic palynology</span> Forensic application of the study of particulate matter

Forensic palynology is a subdiscipline of palynology, that aims to prove or disprove a relationship among objects, people, and places that may pertain to both criminal and civil cases. Pollen can reveal where a person or object has been, because regions of the world, countries, and even different parts of a single garden will have a distinctive pollen assemblage. Pollen evidence can also reveal the season in which a particular object picked up the pollen. Recent research into forensic palynology has seen advancements in DNA barcoding from pollen, to the level of singular pollen molecules, allowing DNA profiles to be created from singular palynomorphs, streamlining the efficiency and accuracy of taxonomic identification.

<span class="mw-page-title-main">Acritarch</span> Microfossils

Acritarchs are organic microfossils, known from approximately 1800 million years ago to the present. The classification is a catch all term used to refer to any organic microfossils that cannot be assigned to other groups. Their diversity reflects major ecological events such as the appearance of predation and the Cambrian explosion.

<span class="mw-page-title-main">Paleobotany</span> Study of organic evolution of plants based on fossils

Paleobotany, also spelled as palaeobotany, is the branch of botany dealing with the recovery and identification of plant remains from geological contexts, and their use for the biological reconstruction of past environments (paleogeography), and the evolutionary history of plants, with a bearing upon the evolution of life in general. A synonym is paleophytology. It is a component of paleontology and paleobiology. The prefix palaeo- or paleo- means "ancient, old", and is derived from the Greek adjective παλαιός, palaios. Paleobotany includes the study of terrestrial plant fossils, as well as the study of prehistoric marine photoautotrophs, such as photosynthetic algae, seaweeds or kelp. A closely related field is palynology, which is the study of fossilized and extant spores and pollen.

<span class="mw-page-title-main">Micropaleontology</span> Branch of paleontology that studies microfossils

Micropaleontology is the branch of paleontology (palaeontology) that studies microfossils, or fossils that require the use of a microscope to see the organism, its morphology and its characteristic details.

<span class="mw-page-title-main">Chitinozoan</span> Group of marine microfossils

Chitinozoa are a group of flask-shaped, organic walled marine microfossils produced by an as yet unknown organism. Common from the Ordovician to Devonian periods, the millimetre-scale organisms are abundant in almost all types of marine sediment across the globe. This wide distribution, and their rapid pace of evolution, makes them valuable biostratigraphic markers.

<span class="mw-page-title-main">Microfossil</span> Fossil that requires the use of a microscope to see it

A microfossil is a fossil that is generally between 0.001 mm and 1 mm in size, the visual study of which requires the use of light or electron microscopy. A fossil which can be studied with the naked eye or low-powered magnification, such as a hand lens, is referred to as a macrofossil.

<span class="mw-page-title-main">Ganapathi Thanikaimoni</span> Indian botanist and palynologist (1938–1986)

Ganapathi Thanikaimoni, often referred to as Thanikaimoni was an Indian palynologist.

<span class="mw-page-title-main">Lennart von Post</span>

Ernst Jakob Lennart von Post was a Swedish naturalist and geologist. He was the first to publish quantitative analysis of pollen and is counted as one of the founders of palynology. He was a professor at Stockholm University 1929–1950.

Cryptospores are microscopic fossilized spores produced by embryophytes. They first appear in the fossil record during the middle of the Ordovician period, as the oldest fossil evidence for the colonization of land by plants. A similar category is miospores, a term generally used for spores smaller than 200 μm. Both cryptospores and miospores are types of palynomorphs.

Dinocysts or dinoflagellate cysts are typically 15 to 100 μm in diameter and produced by dinoflagellates as a dormant, zygotic stage of their lifecycle, which can accumulate in the sediments as microfossils. Organic-walled dinocysts are often resistant and made out of dinosporin. There are also calcareous dinoflagellate cysts and siliceous dinoflagellate cysts.

<span class="mw-page-title-main">Gunnar Erdtman</span>

Otto Gunnar Elias Erdtman was a Swedish botanist and pioneer in palynology. With the publication of his 1921 thesis in German, pollen analysis became known outside Scandinavia. Erdtman systematically studied pollen morphology and developed the method of acetolysis in pollen studies. His handbook An introduction to pollen analysis was instrumental in the development of the discipline. In 1948, he created the palynological laboratory at the Swedish Museum of Natural History in Stockholm. He headed the laboratory until 1971, from 1954 with the title of professor.

<span class="mw-page-title-main">Small carbonaceous fossil</span>

Small carbonaceous fossils (SCFs) are sub-millimetric organic remains of organisms preserved in sedimentary strata.

Alfred Eisenack was a German paleontologist. He was a pioneer of micropaleontology and palynology. His botanical and mycological author abbreviation is "Eisenack".

Francisca Oboh-Ikuenobe is a geologist from Ubiaja in Esan South East Local Government Area of Edo State. She was born August 1962 She specialises in palynology and sedimentology, and is Professor of Geology in the Department of Geosciences and Geological and Petroleum Engineering, and Associate Dean of Academic Affairs in the College of Engineering and Computing, Missouri University of Science and Technology.

<span class="mw-page-title-main">Duntulm Formation</span>

The Duntulm Formation is a sedimentary geologic formation deposited in the Inner Hebrides, Scotland. The formation was previously known as the 'Lower Ostrea Beds', and dates to the Bathonian stage of the Middle Jurassic. The formation is noted for its highly fossiliferous oyster beds, which compose of the species Praeexogyra hebridica. The sedimentary sequence also forms part of the Great Estuarine Group.

<span class="mw-page-title-main">Rosemary Askin</span> New Zealand geologist

Rosemary Anne Askin, also known as Rosemary Askin Cully, is a New Zealand geologist specialising in Antarctic palynology. She was a trailblazer for women in Antarctic science, becoming the first New Zealand woman to undertake her own research programme in Antarctica in 1970.

<span class="mw-page-title-main">Marne di Monte Serrone</span> Geological formation in Italy

The Marne di Monte Serrone is a geological formation in Italy, dating to roughly between 181 and 178 million years ago, and covering the early and middle Toarcian stage of the Jurassic Period of central Italy. It is the regional equivalent to the Toarcian units of Spain such as the Turmiel Formation, units in Montenegro, such as the Budoš Limestone and units like the Tafraout Formation of Morocco.

The Blanowice Formation is a geologic formation in Częstochowa, Poland. It is late Pliensbachian-Lowermost Toarcian age. Plant fossils have been recovered from this formation. Along with the Drzewica Formation is part of the Depositional sequence IV-VII of the late lower Jurassic Polish Basin. Deposits of sequences IV, V, VI and VII make up the Blanowice Formation, being all four sequences are of Pliensbachian age, documented by megaspores (Horstisporites). On the upper strata, “sub-coal beds" cover the sequence VII-lower VIII, while the uppermost part of VIII is identified with the Ciechocinek Formation. The Blanowice Formation has been known for decades thanks to the abundant plant fossils and plant roots, but mostly due to the Blanowice Brown Coals, where the oldest Biomolecules found worldwide have been recovered. The Mrzygłód mine dinocyst assemblage is taxonomically undiversified, containing specimens that are good age indicators allowing relatively precise suggestion of its age. Luehndea spinosa, with a single recovered specimen spans between the Late Pliensbachian (Margaritaus) to the Lowermost Toarcian (Tenuicostatum). Other ocal dinocysts such as Mendicodinium range Late Pliensbachian–Aalenian, a wider stratigraphic range. The lower part of the formation is coeval in age with the Gielniów Formation and Drzewica Formation, Lobez Formation and Komorowo Formation (Pomerania), Olsztyn Formation, the lower part of the Rydeback Member of the Rya Formation, lower Fjerritslev or Gassum Formation, lower and middle Sorthat Formation (Bornholm), Neringa Formation (Lithuania). The upper part is coeval with the lowermost upper Rydeback Member, upper Gassum Formation and lower Lava Formation (Lithuania).

<span class="mw-page-title-main">Sorthat Formation</span>

The Sorthat Formation is a geologic formation on the island of Bornholm, Denmark and in the Rønne Graben in the Baltic Sea. It is of Latest Pliensbachian to Late Toarcian age. Plant fossils have been recovered from the formation, along with several traces of invertebrate animals. The Sorthat Formation is overlain by fluvial to lacustrine gravels, along with sands, clay and in some places coal beds that are part of the Aalenian-Bathonian Bagå Formation. Until 2003, the Sorthat Formation was included as the lowermost part of the Bagå Formation, recovering the latest Pliensbachian to lower Aalenian boundary. The Sorthat strata reflect a mostly marginally deltaic to marine unit. Large streams fluctuated to the east, where a large river system was established at the start of the Toarcian. In the northwest, local volcanism that started in the lower Pliensbachian extended along the North Sea, mostly from southern Sweden. At this time, the Central Skåne Volcanic Province and the Egersund Basin expelled most of their material, with influences on the local tectonics. The Egersund Basin has abundant fresh porphyritic nephelinite lavas and dykes of lower Jurassic age, with a composition nearly identical to those found in the clay pits. That indicates the transport of strata from the continental margin by large fluvial channels of the Sorthat and the connected Röddinge Formation that ended in the sea deposits of the Ciechocinek Formation green series.

<i>Palynodinium</i> Extinct genus of dinoflagellate cysts

Palynodinium is an extinct genus of organic-walled dinoflagellate cyst. It is a fossil species of dinoflagellate cyst used to demarcate the K/Pg boundary, which marks the terminal Cretaceous and the extinction of the dinosaurs. Palynodinium grallator was among the microfossils which lead to the recent discovery of the K/Pg event record in marine sediments of the northeast Pacific.

References

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