Pollen In Sediments Research Articles

Comparison of two concentration methods for pollen in minerogenic sediments

Abstract This study concerns a comparison of the conventional HF method and a method using ZnCl2 as a heavy liquid, combined with HF, for the concentration of pollen in minerogenic sediments. The investigation clearly shows that the ZnCl2 method is as accurate as the HF method and is superior as regards both the concentration and the preservation of pollen grains.

The last interglacial–glacial cycle, Clyde foreland, Baffin Island, N.W.T.: stratigraphy, biostratigraphy, and chronology

A study of the stratigraphic sequence (14C and amino acid age control), marine bivalve faunal changes, and palynology of buried soils and organic-rich sediment collected from the Clyde Foreland Formation in the extensive cliff sections of the Clyde foreland, eastern Baffin Island, N.W.T., suggests the following last interglacial – Foxe (last glaciation) glacial – present interglacial sequence.(1) Cape Christian Member (ca. 130 000 years BP?)Consists of the Sledgepointer till overlain by the Cape Christian marine sediments. In situ molluscan fauna, collected from the marine sediments, contain a moderately warm bivalve assemblage. A well-developed soil that formed on the marine sediments (Cape Christian soil) contains an interglacial pollen assemblage dominated by dwarf birch. U-series dates of > 115 000 and ca. 130 000 years BP on molluscs from the Cape Christian marine sediments suggest that they were deposited during the last interglaciation, here termed the Cape Christian Interglaciation. The development of a subarctic pollen assemblage in the Cape Christian soil has not been duplicated during the present interglaciation, suggesting higher summer temperatures and perhaps a duration well in excess of 10 000 years for the last interglaciation.(2) Kuvinilk MemberConsists of fossiliferous marine sediments, locally divided by the Clyde till into upper and lower units. The Clyde till was deposited by the earliest and most extensive advance of the Foxe (last) Glaciation. Kuvinilk marine sediments both under- and overlying the Clyde till contain the pecten Chlamys islandicus, indicating that the outlet glacier advanced into a subarctic marine environment. Amino acid ratios from in situ pelecypod shells abovę and below the Clyde till are not statistically different, but contrast markedly with ratios obtained from the same species in the Cape Christian Member. Organic horizons within the Kuvinilk marine sediments contain a relatively rich pollen assemblage, although 'absolute' counts are low.(3) Kogalu Member (> 35 00014C years BP)Sediments of the Kogalu Member unconformably overlie those of the Kuvinilk Member, but are of a similar character. The dominant sediments are marine in origin, but in places are divided into upper and lower units by the Ayr Lake till. Amino acid ratios from in situ shells above and below the Ayr Lake till are indistinguishable, but substantially less than those in the Kuvinilk Member, suggesting the two members are separated by a considerable time interval. Radiocarbon dates on shells in the Kogalu marine sediments range from 33 000 to 47 700 years BP, but these may be only minimum estimates. The sea transgressed to a maximum level 70–80 m asl, coincident with the glacial maximum. Subarctic marine fauna of interstadial–interglacial character occur within the Kogalu marine sediments.(4) Eglinton Member (10 000 years BP to present)A major unconformity exists between the Kogalu and Eglinton Members. Ravenscraig marine sediments were deposited during an early Holocene marine transgression–regression cycle; the oldest dates on these sediments are ca. 10 000 years BP. Locally a vegetation mat occurs at the base or within the Ravenscraig unit. Pollen from these beds is sparse, but indicates a terrestrial vegetation assemblage as diverse as that of today. There is no evidence that Laurentide Ice reached the foreland during the last 30 000 years. Eolian sands that overlie a soil developed on the marine sediments record a late Holocene climatic deterioration. Pollen in organic-rich sediments at the base of, and within, the eolian sands record a vegetation shift in response to climatic change.

Pollen distribution in the northeast Pacific Ocean

Distributional patterns of palynomorphs in core tops from the continental margin of the northeast Pacific Ocean (30°–60°N lat 118°–150°W long) reflect the effects of fluvial and marine sedimentation as well as the distribution of terrestrial vegetation. Maximum pollen concentration (grains/cm 3 of marine sediment) occurs off the mouth of the Columbia River and off San Francisco Bay (the outlet of the San Joaquin and Sacramento Rivers) and appears to be coincident with areas of high terrigenous lutite deposition. The abundance of pollen and spores in shelf sediments is extremely variable with high concentrations typical only of the finest sediments. On the slope, rise and abyssal plain, pollen concentration shows a general decrease with distance from shore. This suggests that in the northeast Pacific pollen is transported into the marine environment primarily by rivers and that, in terms of sedimentation, pollen may be regarded as part of the organic component of fine-grained lutum. Pinus, the principal pollen component of marine sediment on the northeast Pacific margin, is concentrated adjacent to the major drainage systems of areas in which pine grows. Tsuga heterophylla, Picea, and Alnus, important components of the temperate conifer forest, are concentrated off the area of their optimal development, western Washington. Quercus, Sequoia, and Compositae concentrations are greater off the southern California coast where they are prominent in the vegetation. The relative (percent) abundance of most of these pollen taxa in marine sediments reflects a positive relationship to their distribution on land. Picea and Alnus are relatively more important north of 45°N, Tsuga heterophylla between 45°–50°N, and Quercus, Sequoia, and Compositae south of 40°N. Pine percentages increase seaward, from less than 10% of the pollen sum in shelf sediments to over 50% in sediments on the abyssal plain. This seems to indicate selective transport of pine pollen. Factor analysis of pollen data from the 61 core tops results in four pollen assemblages. Three of these assemblages ( Quercus-Compositae- Sequoia, Tsuga heterophylla-Pinus, and Alnus-Picea) reflect the distribution of vegetation on the adjacent continent, one ( Pinus) reflects primarily the effects of marine sedimentation.

Pollen grains in lake sediments: Pollen percentages in surface sediments from southern Michigan

Pollen in surface sediments from five lakes in southern Michigan shows evidence of differential deposition. In most lakes, pollen from ragweed occurs in a higher ratio to tree pollen in shallow-water sediment than in deep water. Pine and certain herbs with small pollen grains follow the same pattern. One very deep lake is an exception, with the ratio of ragweed to tree pollen highest in deep-water sediment. Pollen from local aquatics and from willow, which grows along the lake shore, is also unevenly distributed, occurring in highest frequencies near the parent plants. Pollen from deciduous trees, however, occurs in similar ratios at all sampling stations within each lake. Deciduous pollen occurs in uniform ratios, also in older sediment, deposited in the early 19th century, when the landscape was still forested. Percentages of deciduous tree pollen (as percent tree pollen) were compared among lakes. Single samples were taken for this purpose from the deepest part of each lake basin. Oak pollen percentages are higher in three lakes in western Washtenaw County than in three lakes in eastern Washtenaw County. This difference reflects a similar difference in present-day vegetation: second-growth oak forests grow near the lakes in the western half of the county, while all but 5% of the area in the eastern part of the county is farmland. (The difference in the ratio of farmland to forestland in the two parts of the county is not reflected clearly in the ratio of herb pollen to tree pollen, because there is so much variation within each lake.) In 140-year-old sediment, on the other hand, tree pollen percentages in the six samples are homogeneous as shown by a chi-square test. The homogeneity in sediment deposited before the forest was cleared is surprising, because witness-tree data from presettlement time show that the frequencies of tree species in the two areas were quite different. Pollen dispersal at that time must have been effective enough, to counteract differences over distances of a few tens of kilometers in the amounts and kinds of pollen produced by the vegetation.

Late Glacial History of the Upper Wallkill Valley, New York

Final Wisconsinan glaciation of the Wallkill Valley was accomplished by the Wallkill Valley lobe that advanced as far south as the Ogdens-burg-Culvers Gap moraine in New Jersey. As the ice margin retreated northward to the Pellets Island and New Hampton moraines, a proglacial lake was impounded with an outlet at 500 ft. Next, the ice margin retreated to the Wallkill moraine and a new lake outlet was established at 400 ft. Kettle ice in the New Hampton moraine then melted and drained into the 400 ft lake, and pollen sedimentation in New Hampton Bog No. 1 commenced. Analysis of the pollen spectra in New Hampton No. 1 indicates the presence of pollen subzones that are correlated with dated sequences in southern New England and southern New York. Correlation with the Herb Pollen Zone is based on the presence of cold climate indicator pollen even though nonarboreal pollen (NAP) comprises only 11 percent of the spectrum. A radiocarbon date of 12,850 ± 250 years B.P. between the A 1 -A 2 and A 3 subzones confirms correlation and suggests that sedimentation in the T 1 subzone began about 15,000 years B.P. Using the most recent sedimentation rate for Rogers Lake, the basal sediments are calculated to be 14,850 yrs old. A spruce rise in the T 2 subzone is tentatively correlated with the Rosendale re-advance in the Hudson Valley and the Middle-town re-advance in Connecticut. The initial advance into the Wallkill Valley is correlated with the early Woodfordian Kent glaciation of Ohio, Pennsylvania, and western New York. The mid-Woodfordian recessional deposits probably correlate in part with the Valley Heads drift of western New York.

A STUDY ON POLLEN DISPERSAL AND SEDIMENTATION IN THE WESTERN PART OF THE NETHERLANDS

SUMMARY The interpretation of palynological data into a history of the plant communities in a region requires (1) the estimation of the pollen density in the samples, (2) the knowledge of the relative representation rates of the vegetation elements in the pollen spectra and (3) a careful distinction between air-borne and water-borne pollen because of their different recording values. In the present article, a method is described for pollen density determination which is convenient when cores have to be analysed consisting of peat, gyttja and clastic sediments. This method involves the addition of a foreign pollen. Examples are given of the variation which may occur in the pollen density of sediments in a horizontal series of samples. In three cores the pollen densities were determined and the use of this additional information for the interpretation of the analysis data is demonstrated. In a number of nature reserves a comparison was made between the composition of the local stand of vegetation and the pollen sedimentation. To this purpose moss samples were analysed. The representation of the plant communities was generally found to be fair. The dispersal of water-borne pollen was studied by a comparison of the regional vegetation types with the pollen precipitated on river banks and tidal flats; there was also made a series of analyses of the pollen content of the water, which shows that the seasonal variations are so small that the pollen which is precipitated from the water in the regions investigated is not representative for the regional vegetation type. The pollen which is deposited in such conditions may originate from three different sources: (1) the local or regional stand of vegetation, (2) forests or other plant communities in remote upstream areas and (3) peat or gyttja layers or other pollen containing deposits which are eroded by the water currents. A number of examples of these dispersal mechanisms is described in this article. In a few cases it is demonstrated how the determination of pollen density may contribute to the solution of the problem, in which proportion these three dispersal mechanisms have been responsable for the presence of the pollen in the sediment under investigation.

Palynomorphs as Indicators of Nearshore and Offshore Features in Modern Sedimentary Basins: ABSTRACT

Distribution of pollen, spores, cuticles, tracheids, as well as dinoflagellates, hystrichospheres, microforaminifers, and certain other microplankton, may be used within certain limitations to identify or assist in determining sedimentary environments and ancient paleogeographic patterns. Special consideration is given to the modifying influence of marine circulation, currents, tides, etc. on patterns of distribution. Configuration and restrictions of basin and shorelines, patterns of surface or near-surface circulation resulting from prevailing wind regimes (resulting in localized areas of upwelling in different seasons), submarine canyons, and other such agencies and features cause significant modifications on distribution patterns of palynomorphs. Direction, strength, and season of prevailing winds and storms exert some control in distribution of pollen and spores. Down-wind distribution areas show decreasing frequency from source areas. Dilution of palynomorph concentrations in the vicinity of deltas and channels, where an abundant supply of terrigenous sediments is accumulating, seems to lower absolute frequencies of palynomorphs only in main channels and very near the shore. Differential susceptibility to decay, which characterizes these entities, makes it difficult to depend on the presence or absence of particular pollen of plants which make up the communities on the coastal plains to identify nearshore position. Use of total number of spores and pollen in sediments, to determine positions of former shorelines, should be amplified with a consideration of type of sediment at the sampling site and the nature of thanatocoenoses of marine faunas and algae. Cuticles and tracheids are extremely abundant in fine sediments near the shore and decrease offshore. Cuticular fragments greater than 1 millimeter in diameter usually are not carried or are destroyed within a few miles of shore; tracheids greater than 50µ and finer cuticles are deposited in decreasing numbers 50-100 miles offshore. Some kinds of palynomorphs increase in relative frequency, compared with total pollen and spores, with increasing distance offshore. Mangrove and pine are typical of this group. Herbaceous pollen generally is more abundant near the shore. Comparison is made of results of studies of palynomorphs in modern bottom sediments in the Gulf of California, Gulf of Paria, Mediterranean Sea, Sea of Okhotsk, and Gulf of Mexico for the purpose of indicating proximity to shorelines and deltas. End_of_Article - Last_Page 460------------

Palynology of the surface sediments of Great Bahama Bank, as related to water movement and sedimentation

Approximately 130 samples of surface sediment from a series of traverses on the Great Bahama Bank and from other locations in the Bahamas were analyzed palynologically in this study. The investigation was undertaken as an aid to geologic studies of the Bahamas, especially with reference to sedimentation patterns. Fossil pollen and other maceration-resistant microfossils are present in fair abundance in the Bahama surface sediment. The distribution of pine pollen has proved especially significant. This large, buoyant pollen type, once delivered to the water, remains suspended therein for long periods and is eventually deposited in the sediment as a rather sensitive response to hydrographic features on the Bank, especially water turbulence. Analysis of residues from centrifuged sea water west of Andros Island has shown that in July, 1959, five months after the flowering time of pine, samples of the water contained as much as 2,000 pine-pollen grains/100 1 of water. Pine pollen in the water northwest of Andros Island was most abundant at the very edge of the Bank, showing an apparently inverse relationship to distribution of pine pollen in the sediment. The fact that proximity of source is not a prime factor in pine-pollen sedimentation on the Bank is shown by concentrations of pine pollen in sediment near Eleuthera Island, which has no pines, and by the concentration of high values northwest of Andros, in a zone limited on the margins by low values. This distribution is obviously explicable in terms of sedimentation patterns, not source. Pollen highs are regularly found in the sediment from the leeward sides of the larger islands, where water turbulence is minimal and the sediment is prevailingly fine grained. “Microforaminiferal” chitinous inner tests do not show this limitation but are found in abundance in sediment at some stations where pollen highs are not found. The suggested explanation is that the Foraminifera before our maceration treatment are calcareous and are typically bottom dwellers, and hence they are deposited more or less in situ rather than being swept about freely on the Bank. Charts are presented which show distribution of pine pollen, other types of pollen, “microforaminiferal” inner tests, hystrichosphaerids, and HCl-insoluble (organic) residues. The possibility is pointed out that analysis of maceration-resistant microfossils in ancient carbonate banks might yield valuable information about water movements and sedimentation trends during deposition of the bank sediment.

The problem of reworked pollen and spores in marine sediments

Some pollen-and-spore assemblages found in ocean-bottom sediments contain many reworked plant microfossils. In the search for a method to separate the recycled pollen grains and spores from the primary assemblage recovered from Pleistocene and Recent ocean-bottom-core samples, it was found that morphologically distinct Tertiary and older pollen grains and spores accept Safranin O stain differently than do most of the Pleistocene or younger plant microfossils in the same assemblage. Variations in stain acceptance may be a reflection of exine-chemistry changes that took place during the reworking process. High percentages of reworked pollen and spores in sediments formed during periods of continental glaciation are thought to be the result of increased erosion resulting from base-level lowering. Large numbers of recycled plant microfossils in Pleistocene and even pre-Pleistocene sediments may be indicative of decreasing base levels associated with orogenic movements or former periods of continental glaciation. Secondary plant microfossils can offer important clues on the location of the source areas of marine sediments.

Spores, pollen, diatoms and provenance of the Agentine basin sediments

The Argentine Basin is unique in that it contains the largest abyssal sediment deposit in the world, with a mean sediment thickness of about 2 km. In order to investigate the stratigraphy and rate of deposition of the sediments within reach of available cores, pollen, spores and diatoms were studied. The pollen stratigraphy is characterized by the occurrence of three types of pollen spectra, two of which indicate the alternation of glacial and interglacial stages, and the third one representing the postglacial stage. This interpretation is confirmed by a study of the relative abundance of “cold” and “warm” water diatoms in the cores. The rate of postglacial sedimentation ranges from 0 to 5.8 cm/10 3 years and that of the last glacial from 2(?) to 13.8 cm/10 3 years in the cores investigated. The latter rate, which appears rather high for land-derived lutites, may be related to the increase in exposed area of the South American continent west of the narrow submerged shelf, and to greater erosion and stronger winds and currents during low stands of sea level. Of interest is the predominance of such arid-climate indicators as Chenopodiaceae and Ephedra pollen in sediments of the glacial stages, suggesting the existence of large arid regions east of the Andes during times of low sea level. The interglacial stages, on the other hand, are characterized by relatively large areas of humid vegetation, primarily Podocarpus-Nothofagus forest and moorland. Available data suggest that pollen grains and fine-grained land-derived clastic sediments are transported by streams, ocean currents and turbidity currents in essentially the same manner, and therefore the hypothesis is adopted that the provenance of the pollen and spores is related to the provenance of the lutites in which the plant microfossils occur. The provenance of the bulk of the Quaternary lutites appears to be south of the Rio de la Plata, with only a minor contribution from the drainage basin of the river.

Use of Reworked Pollen and Spores for determining the Pleistocene - Recent and the Intra-Pleistocene Boundaries

DURING July of 1962 a two-year palynological investigation of continental shelf and ocean bottom sediments off the eastern coast of the United States was undertaken. (Samples were made available through the courtesy of Lamont Geological Observatory and Woods Hole Oceano-graphic Institution.) Later, samples from a suite of cores collected between Argentina and the Mid-Atlantic Ridge were also added to this investigation of pollen and spore distribution in marine sediments. A total of 349 samples from 21 cores was collected by me. All samples collected were processed and examined. Only three of the 21 cores sampled proved to be completely barren of pollen and spores. All the other cores contained at least some productive samples and in many of the cores most of the processed samples yielded pollen and spores.

Ephedra Pollen in Sediments of the Great Lakes Region

Ephedra spp. and Sacrobatus vermiculatus are common shrubs of dry, open sites in western North America today. Pollen of these plants has been found in surface collections in Minnesota, at high altitudes in the Rocky Mountains, and on an atmopheric slide exposed at 1,500 m over eastern Iowa. These demonstrations of long range carriage of pollen plus the fact that Ephedra pollen grains found at 13 sites in the Midwest are not restricted to the Late—Glacial but not found throughout the Postglacial sequence negate a widely held view the Ephedra was part of the periglacial flora of the Great Lakes region.

On the theory of pollen analysis

A consideration of the theoretical relationship between vegetational percentages and the percentages of pollen in sediments makes it obvious that where species differ in the amounts of pollen they contribute to sediments, pollen diagrams cannot be interpreted quantitatively by means of traditional methods. Under ideal conditions it should be possible, however, to interpret fossil pollen percentages objectively by means of correction for observed differences in pollen contribution. This method is described and demonstrated by its application to the Pine Pollen Zone in a pollen diagram from Vermont. The results imply that our previous subjective vegetational and climatic interpretation of this zone has been without validity. The departures of the real situation from the conditions of an ideal model are used to illustrate a general discussion of some of the subtle but potentially important sources of error that must be evaluated before pollen analysis can be used as a reliable paleoecologic technique.

The problem of rebedded pollen in late-glacial sediments at Taunton, Massachusetts

The occurrence of pollen of tree genera not found in the modern flora of the United States and Canada in late-glacial sediments from the Williams Street bog near Taunton, Massachusetts, is considered evidence of contamination of the sediments with secondary pollen rebedded from pre-Quaternary deposits. Nearby varved clays also contain these pollen types, and because the local till contains little if any pollen, it is concluded that the secondary pollen was carried in glacial meltwater from the vicinity of Tertiary deposits 23 mi. to the NE. The late-glacial bog sediments were apparently contaminated either directly by meltwater streams, or through the erosion and redeposition of meltwater stream deposits. As the secondary pollen spectrum cannot be determined with certainty, it is impossible to interpret the mixed secondary and primary pollen spectrum contained in the late-glacial sediments.

POLLEN PROFILES FROM THE QUEEN CHARLOTTE ISLANDS, BRITISH COLUMBIA

Five peat sections were excavated from muskegs on Langara, Graham, and Moresby Islands of the Queen Charlottes with the primary purpose of reconstructing the postglacial plant succession and associated climatic and physiographic alterations. A secondary purpose was to support or disprove the geological and zoological data favoring the existence of refugia in which biota survived from preglacial or interglacial time. The oldest pollen record tends to support this contention. The record is older than any derived from sections heretofore studied on the northwest coast. Twenty-three plant entities are represented in the bottom sediments below the lodgepole pine maximum which in these other sections marks the oldest peat. In addition, 27% of the coniferous pollen at the base of the section is constituted of climax forest trees, thus implying the presence of long-established forest when pollen sedimentation began. The number and kinds of pollen in the basal peat favor the interpretation that vegetation persisted in refugia through at least the last glaciation. The pollen profiles further corroborate earlier findings for changes in land–sea level relations and for the following postglacial climatic sequence: early cool-moist, warmer and drier (thermal maximum), and late cooler and wetter.