Pollen In Sediments Research Articles

Millennial multi-proxy reconstruction of oasis dynamics in Jordan, by the Dead Sea

Vegetation reconstructions in the Dead Sea region based on sediment records are potentially biased, because the vast majority of them derive from the western side of the sea, and only focus on large areas and time spans, while little is known about extra-local (< 1,000 m radius) to local (< 20 m radius) changes. To fill this gap, we compared a vegetation survey with modern pollen assemblages from the “Palm Terrace” oasis ca. 300 m b.s.l. (below sea level), at the eastern edge of the Dead Sea. This revealed how the oasis vegetation is reflected in pollen assemblages. In addition, two sediment cores were collected from the centre and the edge of a mire at the oasis to reconstruct past vegetation dynamics. We analysed sedimentary pollen and microscopic charcoal, as well as the sediment chemistry by X-ray fluorescence (XRF) and conductivity, focusing on the past ~ 1,000 years. Pollen results suggest that mesophilous Phoenix dactylifera (date palm) stands and wetland vegetation expanded there around ad 1300–1500 and 1700–1900. During the past ca. 100 years, drought-adapted Chenopodiaceae gained ground, partly replacing the palms. Results from elemental analysis, especially of elements such as chlorine, provide evidence of enhanced evaporative salinization. Increasing desertification and the associated decline of mesophilous date palm stands during the past ca. 50 years is probably related to a decrease in annual precipitation and also corresponds to decreasing water levels in the Dead Sea. These have mainly been caused by increasing extraction of fresh water from tributaries and wells, mainly for local agriculture and industry. In the future, with hotter and drier conditions as well as increased use of water, oasis vegetation along the Dead Sea might be at further risk of contraction or even extinction.

Pollen and Foraminifera Approaches to Identify Sediment Sources In The River Mouth Mahakam East Kalimantan

The central role of Mahakam River in the construction of Mahakam Delta is to supply sediment from terrestrial to the river mouth. The river upstream comes from Mount Camaru and the downstream part terminate at Makasar Strait. The surrounding area of the river is overgrown by wet tropical flora that produces pollen. The existence pollen in river sediments as an indicator that sediment came from terrestrial, and foraminifera as an indicator that sediment came from marine. The ratio changes of pollen to foraminifera show that there were differences of sediment source supply. The study was conducted at the river mouth. A shallow core, 200 cm depth, composed of sand and mud and sandy mud, from it taken vertically 11 samples to be analyzed pollen and foraminifera. Sample preparation was using standard methods acetolysis. Meanwhile, sample preparation of foraminifera using Hydrogen Peroxide method. Pollen found at all samples, but foraminifera only found in 8 samples. The data indicating that sedimentation process in the mouth of a river not only gets sediment supplies from terrestrial but also from marine. The quantity of pollen and foraminifera varies vertically. The frequency of pollen much higher than foraminifera that indicates of source sediments dominance came from terrestrial which carried by Mahakam river current. Sonneratia caseolaris pollen continuously found in all samples. Stictogongylus vandiemensis is species foraminifera the most common that followed by Ramulina confossa, both of them come from the sea particularly from the shallow sea.

Analysis of Younger Dryas–Early Holocene pollen in sediments of Paisley Cave 2, south-central Oregon

ABSTRACTPollen analysis from Paisley Cave 2 (35LK3400), in Oregon has produced a record of climate change affecting the Summer Lake Sub-basin during a 7000-year period beginning at roughly 14,500 cal. yr. These sediments provide an opportunity to examine questions concerning human–environmental interaction at the end of the Pleistocene Epoch, during the Younger Dryas climatic event. The sediment deposits show a relatively unchanging early Holocene environment of predominantly xeric conditions with subalpine and marsh communities nearby. Additionally, there is little evidence of culturally significant use of any specific plant species. The data shows that the overall climatic conditions in the region were slightly cooler and perhaps wetter, just prior to the end of the Late Glacial, than today. These results provide important perspective on early settlement patterns and human ecology in the far western region of North America.

Molecular Tracing of the Origin of Six Different Plant Species in Bee Honey Using Real-Time PCR.

The quality of honey is significantly influenced by floral origin. Mislabeling floral species occurs frequently in bee honey products. To protect consumers from economic fraud and maintain a fair market environment, methods to identify floral species in honey are necessary. In our study, real-time PCRs were established, targeting six honey types mainly produced in China (canola, Chinese milkvetch, Chinese chaste tree, locust tree, litchi, and longan). Sensitivity testing on DNA from plant tissues exhibited LODs of about 0.5-5 pg/μL. For DNA extracts of pollen sediments from different honey species, LODs ranged from 13.6 to 403.2 pg/μL. In an experiment to determine the practical LODs of honey in which adulterant honey was spiked in the genuine honey, adulterant honey as low as about 0.1-0.5% was detected in 90-100% in 10 parallel tests. Additionally, pollen was spiked in the honey and stored under various conditions to investigate the migration of pollen DNA into the honey supernatant. Finally, the efficiency of our method was investigated by testing honey samples of unknown compositions from different geographic regions. Of the 159 honey samples that were supposed to be monofloral that had been collected in five provinces, a small portion were found to be contaminated with foreign pollen (7%). The methods proved to be specific, sensitive, and reliable in identifying the six plant species in honey, which would be a useful tool during the market supervision and QC of honey products.

Spatial distribution of allergenic pollen through a large metropolitan area.

For nearly a decade, the majority of the world's population has been living in cities, including a considerable percentage of people suffering from pollen allergy. The increasing concentration of people in cities results in larger populations being exposed to allergenic pollen at the same time. There is almost no information about spatial distribution of pollen within cities as well as a lack of information about the possible impact to human health. To obtain this increasing need for pollen exposure studies on an intra-urban scale, a novelty screening network of 14 weekly changed pollen traps was established within a large metropolitan area-Berlin, Germany. Gravimetric pollen traps were placed at a uniform street-level height from March until October 2014. Three important allergenic pollen types for Central Europe-birch (Betula), grasses (Poaceae), and mugwort (Artemisia)-were monitored. Remarkable spatial and temporal variations of pollen sedimentation within the city and the influences by urban local sources are shown. The observed differences between the trap with the overall highest and the trap with the overall lowest amount of pollen sedimentation were in the case of birch pollen 245%, grass pollen 306%, and mugwort pollen 1962%. Differences of this magnitude can probably lead to different health impacts on allergy sufferers in one city. Therefore, pollen should be monitored preferably in two or more appropriate locations within large cities and as a part of natural air quality regulations.

Modern pollen assemblages in topsoil and surface sediments of the Xingyun Lake catchment, central Yunnan Plateau, China, and their implications for interpretation of the fossil pollen record

Modern pollen data from topsoils and surface lake sediments are commonly used as modern analogues and as climate calibration data for reconstructing vegetation and climate history from fossil pollen profiles. However, the potential differences and biases in pollen assemblages from these two sample types, as well as the processes of pollen sedimentation in lake basins, have received relatively little attention. Here we present the results of the analysis of modern pollen assemblages in 10 surface sediment samples and 25 topsoil samples from Xingyun Lake and its catchment, a shallow alpine lake site in the central Yunnan Plateau, southwest China. The modern pollen assemblages from both types of samples are mainly composed of Pinus, evergreen and deciduous oaks, Alnus, Poaceae, Artemisia, Brassicaceae and Amaranthaceae, and are consistent with the modern vegetation. Although the pollen assemblages of topsoil samples vary with the type of modern local vegetation, in general they are representative in term of the composition of the main pollen taxa, with some significant differences in the case of some vegetation types. With regard to the surface lake sediment samples, the pollen assemblages are relatively constant with no significant changes with sample location and water depth. The main pollen taxa are Pinus (around 40%), Alnus (around 18%) and Poaceae (around 11%), with relatively high percentages of evergreen and deciduous oaks, Betula (2–4%), and low percentages of Ulmus, Rosaceae, Corylus, Cupressaceae, Euphorbiaceae, Myrica and Elaeagnaceae. This composition is a good representation of the main types of catchment vegetation. The relative uniformity of the pollen assemblages from the lake surface samples may partly result from the effect of currents in redistributing the pollen input to the lake by rivers and wind. Therefore, we suggest that it is better to use pollen data from surface lake sediments, rather than from topsoils from the lake catchment, for interpreting fossil pollen assemblages of lake sediment cores. Our results indicate that the pollen assemblages in a sediment core from any part of Xingyun Lake are likely to provide a reliable record of the regional vegetation history and thus climatic change. Our modern pollen results, together with modern pollen data from other surface lake sediment samples along a large altitudinal gradient from Yunnan to southwest Sichuan Province, were used to reanalyze fossil pollen assemblages during the Last Glaciation period at Xingyun Lake. The results show that the vertical vegetation belts decreased in altitude from late Marine Isotope Stage 3 (late MIS3) to the Last Glacial Maximum (LGM) and then increased during the Last Deglaciation.

Seasonal patterns of pollen sedimentation in Lake Montcortès (Central Pyrenees) and potential applications to high-resolution paleoecology: a 2-year pilot study

Lakes with varved sediments are especially well suited for paleoecological study, from annual to even seasonal resolution. The interpretative power of such high-resolution paleoenvironmental reconstructions relies on the availability of modern analogs with the same temporal resolution. We studied seasonal pollen sedimentation in varved Lake Montcortès, Central Pyrenees (Spain), as a modern analog for high-resolution reconstruction of Late Holocene vegetation and landscape dynamics. Seasonal samples were obtained from sediment traps that were submerged near the maximum water depth for a 2-year period (fall 2013 to fall 2015). Seasonal pollen sedimentation was compared with meteorological variables from a nearby weather station. Bulk pollen sedimentation, dominated by Pinus (pine) and Quercus (oak), followed a clear seasonal pattern that peaked during the spring/summer, coinciding with maximum temperature and precipitation, minimum relative humidity and moderate winds from the SSE. Pollen sedimentation lags (PSL) were observed for most pollen types, as substantial amounts of pollen were found in the traps outside of their respective flowering seasons. Two pollen assemblages were clearly differentiated by their taxonomic composition, corresponding to spring/summer and fall/winter. This pattern is consistent with existing interpretation of the sediment varves, specifically, that varves are formed by two-layer couplets that represent the same seasonality as pollen. We concluded that pollen sedimentation in Lake Montcortès exhibits a strong seasonal signal in the quantity of pollen, the taxonomic composition of the pollen assembalges, and relationships between the pollen and meteorological variables. Thus, varved sediments provide a potentially powerful tool for paleoecological reconstruction at seasonal resolution. This method could be used not only to identify paleoenvironmental trends, but also to identify annual layers and therefore date sediments, even in the absence of evident sediment laminations. A satisfactory explanation of PSL will require further studies that examine internal lake dynamics and pollen production/dispersal patterns.

How palynology was born

Ecology Much of today's understanding of past ecosystems comes from studies of pollen in sediments, a field called palynology. In a Perspective, Birks et al. highlight the pioneering work of Lennart von Post, who published the first quantitative analysis of pollen. One hundred years ago, von Post

The effects of anthropogenic land cover change on pollen-vegetation relationships in the American Midwest

Abstract Fossil pollen assemblages provide information about vegetation dynamics at time scales ranging from centuries to millennia. Pollen-vegetation models and process-based models of dispersal typically assume stable relationships between source vegetation and corresponding pollen in surface sediments, as well as stable parameterizations of dispersal and productivity. These assumptions, however, are largely unevaluated. This paper reports a test of the stability of pollen-vegetation relationships using vegetation and pollen data from the Midwestern region of the United States, during a period of large changes in land use and vegetation driven by Euro-American settlement. We compared a dataset of pollen records for the early settlement-era with three other datasets of pollen and forest composition for two time periods: before Euro-American settlement, and the late 20th century. Results from generalized linear models for thirteen genera indicate that pollen-vegetation relationships significantly differ (p Fagus, Betula, Tsuga, Quercus, Pinus , and Picea . The estimated pollen source radius for the 8 km gridded vegetation data and associated pollen data is 25–85 km, consistent with prior studies using similar methods and spatial resolutions. Hence, the rapid changes in land cover associated with the Anthropocene affect the accuracy of ecological predictions for both the future and the past. In the Anthropocene, paleoecology should move beyond the assumption that pollen-vegetation relationships are stable over time. Multi-temporal calibration datasets are increasingly possible and enable paleoecologists to better understand the complex processes governing pollen-vegetation relationships through space and time.

Characteristics of pollen in surface sediments from the southern South China Sea and its paleoclimatic significance

We investigated pollen distributions in surface sediments of the southern South China Sea (SCS) and their relation to seabed topography and the environment of the terrigenous sources. In this study, we analyzed 62 surface sediment samples collected from the SCS through modern pollen analysis methods. The results of our study can be summarized as follows. (1) trilete spores dominate the pollen and spore spectrum, which reflects the dominance of ferns in the Nansha Island vegetation. Similar pollen characteristics were found for different periods of high sea level and global warming after 12Ma in ODP site 1143 and site 18287 in the southern South China Sea. Most pollen and spores on the Kalimantan Island coast are produced by herbaceous plants and trees, while few trilete spores produced by ferns are present. Furthermore, similar pollen characteristics were found for different periods of low sea level and global cooling in ODP site 1143 and site 18287. (2) Through an analysis of pollen samples from a transect line extending from the northwest to the southeast, the complex terrain of the Nansha Islands was observed to be unsuitable for pollen migration through ocean currents. Pollen counts in samples collected near the southern Nansha Islands decreased gradually from the east and west continental shelf areas to the central basin area. However, the same analysis confirmed that the Nansha Trough facilitates the entry, dispersal, and storage of pollen from external sources. (3) Principal component analysis (PCA) of samples collected from two different water depths in the southern SCS demonstrates that trilete spores and monolete spores in 4 samples near the Mekong River with water depths of <200m are transported primarily by river flow. Conversely, pollen and spores mainly transported by rivers near Kalimantan Island were found at water depths of >200m. However, analysis of samples from the northern SCS in a previous study obtained different results.

From wetland to commercial centre: the natural history of Wyspa Spichrzów (“Granary Island”) in medieval Gdańsk, northern Poland

This paper describes the analyses of pollen, non-pollen palynomorphs, macroremains and geochemistry in sediments from archaeological excavations at Wyspa Spichrzow (“Granary Island”) in Gdansk, northern Poland. The aim of this study was to reconstruct the environmental conditions in this part of the town in the period preceding its occupation and during its transformation with the establishment of a trade centre and an increasing number of granaries, warehouses and workshops. The results show that this area was originally covered by wetlands typical of river oxbows, with a landscape formed by alder woods, shallow pools of water, fens and patches of wet meadows. Around the 9th–10th centuries, a distinct lowering of the groundwater table reduced the pools, and the alder stands also reduced. These changes coincided with the Medieval Climatic Anomaly. Drying of the ground could have been an important factor enabling expansion of settlement in the Gdansk area. Between the 10th and 13th–14th centuries, the area around the investigated sites was probably used as pasture, as shown by high frequencies of coprophilous fungal spores. A large representation of cereal pollen and pollen and macroremains of field weeds reflects crop transport and storage on the island from ca. the 13th/14th centuries in the northern part of the area and the 15th/16th centuries in its southern part. The increasing human impact caused development of a rich flora associated with human activities, habitat enrichment by nitrogen and phosphorus, and heavy metal pollution from the beginning of the 13th century.

Environmental change in Guanabara Bay, SE Brazil, based in microfaunal, pollen and geochemical proxies in sedimentary cores

The exponential development of human activities during the last century has caused a negative impact on all environmental compartments, including coastal areas. Guanabara Bay-SE Brazil has been subjected to significant environmental pollution from increasing urban and industrial development in the last few decades. The major sources of pollution included municipal wastewater, deforestation, urban runoff and industrial effluents. A sediment deposit constitutes a continuous record of the history of a waterbody and its catchment in a chronological sequence, where the information contained in each sediment stratum provides a more or less clearly defined image of a period in the ecosystems history. In the present study, we have investigated the environmental change in the last decades using recent sediments cores along the coastal area of Guanabara Bay. Geochemical trends in coastal sediment depth profiles have been extensively used as indicators of historical pollution, especially when combined with the analysis of biological remains (foraminifera and pollen) in sediments have provided valuable information on respective contribution of terrestrial and anthropogenic inputs into coastal bays. Three sediment cores (∼200 cm long) were taken from different areas inside Guanabara bay were interpreted based on sedimentological, foraminifera, pollen, geochemical and historical data for the last 5000 years. High concentrations of metals (Pb, Ni, Cu, Cr, Zn and Mn) were observed in the three sediment cores over approximately the last hundred years. This is also matched by an increase over time in the foraminifera species Ammonia tepida and a decline in the species Buliminella elegantissima. A. tepida is commonly found in restricted and highly polluted environments, whereas, B. elegantissima is more sensitive to environmental deterioration. Pollen analysis shows a gradual decrease in forest and mangrove vegetation since the European settlement and an increase in field vegetation that has accelerated in recently, together with the introduction of exotic species.

Holocene vegetation succession and responses to climate change in the northern sector of Northeast China

Sediment pollen samples from the Huola Basin in the northern sector of northeast China, and surface pollen samples from its environs, were analyzed to reconstruct accurately the historical response of vegetation to climate change since 9100 cal yr BP. Pollen analysis of the Huola Section indicates that vegetation experienced a transformation from early-mid Holocene warm-cold mixed vegetation to late Holocene cold-temperate vegetation. From 9100 to 6000 cal yr BP, the study area was warmer and moister than at present, developing Corylus, Carpinus, Pinus, Picea, Betula and Larix-dominated forests. Two cooling events at 6000–5000 and 3500–2500 cal yr BP led to a decrease in Corylus, Carpinus and other warmth-loving vegetation, whereas cold temperate forests composed of Larix and Betula expanded. After 2500 cal yr BP, Larix and Betula dominated cold-temperate vegetated landscapes. The Holocene warm period in NE China (9100–6000 cal yr BP) suggests that such warming could have resulted in a strengthening of the influence from East Asian Summer Monsoon on northernmost NE China and would have benefited the development of warm-temperate forest vegetation and an improved plant load, which also provides the similarity model for the possible global warming in the future.

Pollen-detected altitudinal migration of forests during the Holocene in the mountainous forest–steppe ecotone in northern China

Distributed on the margin of the influence of the Asian monsoon, the forest–steppe ecotone in northern China is sensitive to climate change. Previous paleovegetation reconstructions in this region have led to inconsistent explanations of paleovegetation dynamics across sites. We hypothesized that the patterns observed are related to altitudinal migration of forests across mountains in this region. We combined eight lake sediment pollen records to explain how three forest types dominated by the tree genera Pinus, Quercus, and Betula changed in response to temporal and spatial monsoon changes within the forest–steppe ecotone during the Holocene. Modern pollen assemblages showed that areas with large altitude range could support more forests, which was further confirmed by the spatial patterns of late-Holocene forest distribution under dry climate. Our results confirmed that altitudinal migration of forests might exist in this region. This kind of altitudinal migration of forests under different altitudinal ranges could help to explain the inconsistent patterns observed in arboreal pollen across sediment cores as well as the non-linear response of horizontal forest distribution in relation to climate change.

Long-term man–environment interactions in the Bolivian Amazon: 8000 years of vegetation dynamics

Only few studies documenting the vegetation history of the Llanos de Moxos, one of the largest seasonally flooded wetland areas in South America, are available and little is known about the environmental impact of pre-Columbian settlements. We use radiocarbon-dated terrestrial plant macrofossils to establish a sound chronology and palynological analyses to reconstruct the vegetation and fire history of the Lago Rogaguado area. The sedimentary pollen and spore record suggests that wetland and wooded savannah (Cerrado) environments occurred around the lake between 8100 and 5800 cal BP. Fire activity was high during this period and was probably connected to the dry Cerrado environments. The pollen evidence suggests early plant cultivation (Zea mays, Annonaceae and Cucurbitaceae) from 6500 cal BP onwards, which is significantly earlier than hitherto assumed for Amazonia. Gallery forests expanded after 5800 cal BP, when fire activity strongly declined. Forest expansion intensified around 2800 cal BP and continued until 2000 cal BP, when forest cover reached its maximum and fire activity its minimum. The late-Holocene forest expansion to the south and the decrease of fire activity may have resulted from a climatic shift to moister conditions (possibly a shorter dry season). New crops (e.g. Avena-type) or adventive plants (e.g. Rumex acetosella-type) document the impact of European economies after ca. 500 cal BP. Land use intensity remained rather stable over the most recent centuries, arguing against a collapse of settlements in response to the arrival of Europeans, as reconstructed from other Amazonian pollen records.

Artemisia pollen-indicated steppe distribution in southern China during the Last Glacial Maximum

The Last Glacial Maximum (LGM) was the coldest period during the previous 20,000years. There have been different points of views on steppe distribution during the LGM period in southern China, partly due to the different interpretations of Artemisia occurrences. To make a reliable interpretation of the pollen fossil Artemisia, the modern distribution of Artemisia species and the relationship of pollen with climate and vegetation over a large spatial scale in China was thoroughly analyzed. Information about Artemisia species and pollen distributions used in this paper were collected from published works completed by other researchers as well as ourselves. The southern limit of steppe vegetation during the LGM period was interpreted from the published contour map of Artemisia pollen percentages during the LGM. Artemisia species in China are mostly distributed either in the horizontally distributed steppe regions or in the vertically distributed desert-steppe in the desert region, which indicates a cold and dry climate. The steppe is a distribution center of Artemisia pollen. Fractions of Artemisia in surface pollen assemblages are lower in both the desert and the temperate forest. Neither high Artemisia species cover nor high percentages of Artemisia pollen were found in the coast areas of China. Twenty-five percent of Artemisia pollen in sediments might indicate a local occurrence of steppe vegetation. Percentages of Artemisia pollen in the subtropical and tropical forest are less than 10%. A close relationship between Artemisia pollen and temperate steppe in China is demonstrated. The southern edge of the steppe vegetation during the LGM might be along the middle reach of the Yangtze River. Our results support the hypothesis that the isolated high fraction of Artemisia pollen along the northern edge of the South China Sea was transported from a large source area.

Geophysical features influence the climate change sensitivity of northern Wisconsin pine and oak forests.

Landscape-scale vulnerability assessment from multiple sources, including paleoecological site histories, can inform climate change adaptation. We used an array of lake sediment pollen and charcoal records to determine how soils and landscape factors influenced the variability of forest composition change over the past 2000 years. The forests in this study are located in northwestern Wisconsin on a sandy glacial outwash plain. Soils and local climate vary across the study area. We used the Natural Resource Conservation Service's Soil Survey Geographic soil database and published fire histories to characterize differences in soils and fire history around each lake site. Individual site histories differed in two metrics of past vegetation dynamics: the extent to which white pine (Pinus strobus) increased during the Little Ice Age (LIA) climate period and the volatility in the rate of change between samples at 50-120 yr intervals. Greater increases of white pine during the LIA occurred on sites with less sandy soils (R² = 0.45, P < 0.0163) and on sites with relatively warmer and drier local climate (R² = 0.55, P < 0.0056). Volatility in the rate of change between samples was positively associated with LIA fire frequency (R² = 0.41, P < 0.0256). Over multi-decadal to centennial timescales, forest compositional change and rate-of-change volatility were associated with higher fire frequency. Over longer (multi-centennial) time frames, forest composition change, especially increased white pine, shifted most in sites with more soil moisture. Our results show that responsiveness of forest composition to climate change was influenced by soils, local climate, and fire. The anticipated climatic changes in the next century will not produce the same community dynamics on the same soil types as in the past, but understanding past dynamics and relationships can help us assess how novel factors and combinations of factors in the future may influence various site types. Our results support climate change adaptation efforts to monitor and conserve the landscape's full range of geophysical features.

Reviving extinct Mediterranean forest communities may improve ecosystem potential in a warmer future

The Mediterranean Basin is the region of Europe most vulnerable to negative climate‐change impacts, including forest decline, increased wildfire, and biodiversity loss. Because humans have affected Mediterranean ecosystems for millennia, it is unclear whether the region's native ecosystems were more resilient to climate change than current ecosystems, and whether they would provide sustainable management options if restored. We simulated vegetation with the LandClim model, using present‐day climate as well as future climate‐change scenarios, in three representative areas that encompass a broad range of Mediterranean conditions and vegetation types. Sedimentary pollen records that document now‐extinct forests help to validate the simulations. Forests modeled under present climate closely resemble the extinct forests when human disturbance is limited; under future scenarios, characterized by increased temperatures and decreased precipitation, extinct forests are projected to re‐emerge. When combined with modeling, paleoecological evidence reveals the potential of native vegetation to re‐establish under current and future climate conditions, and provides a template for novel management strategies to maintain forest productivity and biodiversity in a warmer and drier future.

Temperature profile around a basaltic sill intruded into wet sediments

The transfer of heat into wet sediments from magmatic intrusions or lava flows is not well constrained from field data. Such field constraints on numerical models of heat transfer could significantly improve our understanding of water–lava interactions. We use experimentally calibrated pollen darkening to measure the temperature profile around a basaltic sill emplaced into wet lakebed sediments. It is well known that, upon heating, initially transparent palynomorphs darken progressively through golden, brown, and black shades before being destroyed; however, this approach to measuring temperature has not been applied to volcanological questions. We collected sediment samples from established Miocene fossil localities at Clarkia, Idaho. Fossils in the sediments include pollen from numerous tree and shrub species. We experimentally calibrated changes in the color of Clarkia sediment pollen and used this calibration to determine sediment temperatures around a Miocene basaltic sill emplaced in the sediments. Results indicated a flat temperature profile above and below the sill, with T >325°C within 1cm of the basalt-sediment contact, near 300°C at 1–2cm from the contact, and ~250°C at 1m from the sill contact. This profile suggests that heat transport in the sediments was hydrothermally rather than conductively controlled. This information will be used to test numerical models of heat transfer in wet sediments on Earth and Mars.

Palynological analysis of extinct herbivore dung from Patagonia, Argentina

Dung pollen studies can contribute information to the paleodiet and paleoenvironmental knowledge during the Pleistocene–Holocene transition. In this study, pollen analysis of extinct megaherbivore dung dated at 10,530 ± 620 BP was performed. Random samples from extinct herbivore dung, level 18, were collected from the archaeological excavation Cerro Casa de Piedra 7 (CCP7) (Argentine Patagonia). These samples were ascribed to ground sloths, Family Mylodontidae. Pollen extraction was carried out by acetolysis. The results were compared with microhistological analyses of feces and with sedimentary pollen analysis of the site. The diet items mainly consisted of Poaceae together with Apiaceae, Caryophyllaceae, Apiaceae Azorella type, Asteraceae subf. Asteroideae, Nassauvia, Perezia, Acaena, Ericaceae/Empetrum and Ephedra. A taxonomic coincidence between the palynological and microhistological analyses that permitted the determination of diet items was observed. The Poaceae and Apiaceae dominance allows supposing the grass steppe and the Nothofagus undergrowth as food areas for megaherbivores. The greater diversity of pollen grains in feces than in sediments due to the contribution of taxa with zoophilous pollination (regularly scarce or absent in sedimentary studies) demonstrates the value of dung analysis to paleoenvironmental reconstructions.