Palynological Record Research Articles

A remarkable Late Saalian (MIS 6) loess (dust) accumulation in the Lower Danube at Harletz (Bulgaria)

While numerous high-resolution studies concerning Last Glacial aeolian sequences are available for Europe, the approach of the penultimate glacial in this geographical area is still poorly developed. In order to bridge this gap, this study focuses on the Bulgarian sequence of Harletz, along the Danube River, where extremely high sedimentation rates allow the depiction of high-resolution signals during MIS 6. At Harletz in NW Bulgaria on the western bank of the Ogosta River (tributary of the Danube) a 20 m thick loess-palaeosols section was cleaned and sampled for a multi-disciplinary study and detailed pedostratigraphic approach. High-resolution continuous bulk sampling (5 cm) was carried out to characterise sedimentary grain size, magnetic properties (including magnetic susceptibility and its frequency dependence), colour reflectance (1 cm), and organic carbon. Geochronological control is based on 16 samples collected for OSL and MET-pIRIR dating. Using a cyclo-stratigraphic approach of the sequence combined with dating constraints provided by both MET-pIRIR dates and the age of a tephra layer occurring at a depth of 12 m within the main loess unit, we can demonstrate that the Harletz section exhibits a 10 m thick Late Saalian (Marine Isotope Stage 6, MIS 6) loess accumulation unique in Europe. The lower part of the main loess unit is 4 m thick and overlies a basal brown soil complex allocated to MIS 7, which includes an exceptionally thick (4 m) and detailed succession of loess and four incipient soil horizons never described in European loess until now. The closest and best-dated high-resolution palaeoenvironmental archive suitable for comparison comes from Lake Ohrid located about 400 km to the SW of Harletz. The Ohrid palynological record shows a progressive step-by-step evolution in climate and in environmental change during the transition between MIS 7 and MIS 6 from which a parallel with the Harletz pedosedimentary succession can be proposed. During the younger part of MIS 6 (160-129ka), steppe vegetation with abundant herbs (Artemisia) is dominant in the Lake Ohrid record, in good accordance with a global enhancement of aeolian dynamics, especially well recorded in sections located close to the Danube River from Serbia to Bulgaria and Romania (L2 loess). According to interpretations stemming from this study, the silts and fine sands building the Harletz loess section would have been transported from the Danube braided river system located (at that time) at about 4.5 km to the NW. Based on our data, the main loess units are characterised by a very low to a total absence of coarse sand particles. By contrast, during the Eemian interglacial (MIS 5e), and to a lesser extent throughout MIS 5 and during MIS 3 interstadials, the long distance transport of silt and fine sand particles is stopped and a weak aeolian sedimentation is likely driven by north-easterly winds transporting coarse sand grains from the proximal Ogosta River sandy banks. Finally, the weak development of Last Glacial loess (4 m max.) likely results from a rapid infilling of the sedimentary trap during the Saalian, then followed by a strong anthropogenic erosion of the topsoil and of the upper part of the loess profile since the Early Holocene (Neolithic).

Treeline composition and biodiversity change on the southeastern Tibetan Plateau during the past millennium, inferred from a high-resolution alpine pollen record

Climate variability has been impacting the terrestrial ecosystems. However, some important processes relating to the response of vegetation to climate change in alpine regions, such as treeline composition and associated plant diversity change, have not been well understood in terms of multi-centennial scales. Here, we present a well-dated high-resolution palynological record from Basomtso, southeastern Tibetan Plateau (TP), to discuss the vegetation change and the relevant climate forcing. Our results manifest that the treeline position, composition and plant diversity around Basomtso did change greatly during the past millennium. The cold events (ca. 720-650 cal yr BP and ca. 400-50 cal yr BP) were considered crucial to force these changes. Cold temperature limited the growth of trees in the high elevations and thus led to downslope movement of treeline and conspicuous decrease of dominant tree species. Space and resource released from the upper forest triggered shrub and herb taxa expanded to lower elevations and even new species can dispersed to this area and survived, leading to changes in vegetation composition and diversity. Although the climate warming is pronounced since the 20th century, treeline distribution, vegetation composition and species diversity seem have not been recovered from the previous cold period. And the vegetation succession in the mountains of the southeastern TP will probably develop slowly in the coming decades. Our results highlight the need for long-term climate and vegetation monitoring and analysis in order to better understand the regional dynamics of treeline movement and plant diversity change during climate transition period.

A multi-proxy shallow marine record for Mid-to-Late Holocene climate variability, Thera eruptions and cultural change in the Eastern Mediterranean

The River Nile catchment is considered the major source of nutrient-rich freshwater and sediment draining into the eastern Mediterranean Sea. Thus, exceptional high-resolution record from the Nile Littoral Cell likely traces changes in the Nile outflows related to climatic changes driven by the monsoonal system. This study used multi-proxy analyses combining sedimentological, geochemical and organic stable isotope data along with foraminiferal data in a southeastern Levantine inner shelf sedimentary sequence to understand Mid - to Late Holocene northeast African climate variability. The palynological record is used to reconstruct local scale changes in the regional vegetation related to the Mediterranean climate system. The analyzed records reveal multi-decadal to centennial pacing of paleoceanographic and paleoclimatic changes, with most prominent events recorded at 4.28, ∼3.6 and at 2.9 kyr BP.These transitional periods characterized by simultaneous high δ15N values and low total organic carbon (TOC) suggest drier climatic conditions, decrease in Nile discharge, leading to lower nutrient supply. A stable and arid climate during Mid-Late Holocene (∼4.5–3.6 cal kyr BP) associated with a weaker monsoon system as well as with a weaker Mediterranean climate system is indicated based on high and constant sedimentation rates (∼400 cm kyr−1), along with relatively stable values and only occasional weak fluctuations documented in all of the proxies. This climatic pattern is punctuated by a peak in maximum aridity at 4.28 kyr BP evidenced by low TOC value and low arboreal pollen (AP) and Artemisia/Chenopodiaceae (A/C) pollen ratios and the sharp decline in the abundance of benthic foraminifera Cribroelphidium poeyanum and Valvulineria bradyana. This change corresponds with the well-studied 4.2 kyr BP drought event in the Middle East, Mesopotamia and south Asia.During the late Holocene (∼3.6–2.8 cal. Kyr BP) the climate became unstable characterized by shifts between relatively wetter and drier conditions as evident in considerable fluctuations in all proxies. Maximum positive excursions of TOC values, C/N ratio along with high dominance of opportunistic foraminiferal species (e.g., Ammonia tepida) indicate northeast African wetter conditions and increased Nile discharge at 3.5, 3.3, 3.2 and 3.0 kyr BP. The distinct and abrupt transition from a stable to an unstable climate regime around 3.6 kyr BP may have been influenced by the Thera volcanic eruption. Thus, the sedimentary record investigated in this study may provide evidence for the impacts of this well-known volcanic eruption not just on the climate regime in the Levant but also on the ancient Near East and Egypt.

An 8500-year palynological record of vegetation, climate change and human activity in the Bosten Lake region of Northwest China

Palynological dataset for the XBWu-46 sediment core extracted from Bosten Lake at the south-eastern end of the Tian Shan, Northwest China, contains a climate record divided into three major intervals: a period of increasing aridity (ca. 8540–4000 cal. yr BP), a peak arid phase (ca. 4000 to 2000/1500 cal. yr BP), and an interval of increasing humidity towards the core top (ca. 60 cal. yr BP). Correlation with other climate proxies from different regions implies that hydrological conditions in Northwest China were governed by Asian summer monsoon precipitation during the early and middle Holocene and that the increase in humidity over the last two millennia was controlled by westerly-derived precipitation. Regional evidence for early human activities in the lake sediments starts to accumulate from the onset of the driest interval comprising records of enhanced charred grass fragment concentrations (since ca. 4350 cal. yr BP), and pollen of Cerealia type (since ca. 4000 cal. yr BP), Xanthium (since ca. 3700 cal. yr BP), and Cannabis type (since ca. 2500 cal. yr BP). These signals are likely related to early agro-pastoral populations of regional Andronovo Culture that, according to archaeological data, appeared in the south-eastern Tian Shan around 4000 cal. yr BP. In addition, increased Xanthium pollen and charred grass fragment abundances point to enhanced human impact linked to intensified Silk Road activities during the Han dynasty (206 BCE–220 CE).

New insights through the palynological record of the Lower Cretaceous Lagarcito Formation, Argentina: Paleoenvironmental implications

The palynological content of the Lagarcito Formation at the East of the Sierras de Guayaguas, San Juan province, central-western Argentina, is analyzed. The study of the Albian palynoflora of the Lagarcito Formation at the La Yesera section, Sierras de Guayaguas, allowed the identification of 64 fossil taxa from eighteen productive samples. A detailed botanical assignation of the palynomorphs, and the statistical analysis of the palynoflora, was performed in order to characterize the local and regional plant distribution. Differences in the palynofloristic content of the three lacustrine episodes productive in palynomorphs, were discussed. At the base of the section, ferns and bryophyte spores dominate the palynoflora. The second and third lacustrine episode showed a prevalence of gymnosperms mainly represented by the monosulcate Cycadopites-Monosulcites complex. The freshwater algae corresponding to the aquatic community are abundant through the section. The presence of interstratified gypsum towards the top of each lacustrine episode indicates a drastical reduction in the lacustrine system due to high levels of evaporation. The comparison of the studied microflora with the palynoflora recovered from the La Cantera Formation in the same basin gave evidence of more humid conditions up in the stratigraphic column.

Palynological record of Holocene vegetation and climate changes in a high-resolution peat profile from the Xinjiang Altai Mountains, northwestern China

A high-resolution pollen record in a peat sequence from the Altai Mountains of Xinjiang, China, allows reconstruction of the regional vegetation and climate changes that occurred during the Holocene. Pollen distributions from the sequence indicate that the vegetation community in the Altai Mountains region transitioned through five general phases: forest and desert steppe, wet steppe, desert steppe, steppe, and finally forest and desert steppe. These vegetative phases imply that the regional climate changed from a cold and dry early Holocene to a warmer and wetter early-mid Holocene and then to a cold and rather dry mid-Holocene that was followed by a cool and wet late Holocene and finally by warm and dry conditions for the last millennium. These regional changes in climate are roughly consistent with local changes previously reconstructed from organic geochemical paleoclimate proxies in the same peat sequence by Zhang et al. (2016), but with some minor but important differences that reflect local factors.Regional comparisons reveal that the Holocene climate changes in the Altai Mountains are generally consistent with those of most arid central Asian regions that are influenced mainly by westerlies. However, they are out-of-phase with the climate histories of regions controlled by the Asian monsoons, indicating that the Asian monsoons did not extend to the high-altitude mountain regions of arid central Asia during the Holocene. We postulate that the regional Holocene moisture variations have been mainly modulated by NAO variations that affected transport of water vapor from the North Atlantic Ocean by the westerlies. Moreover, local factors that include topography of the mountains and glacial meltwater events in the high-altitude regions also contributed to the climate changes in the Altai Mountains. In addition, air temperatures related to summer insolation of the Northern Hemisphere might have played an important role in modulating moisture in the region, but only after the local montane ice-sheets had disappeared by the mid-Holocene.

A continental record of the Carnian Pluvial Episode (CPE) from the Mercia Mudstone Group (UK): palynology and climatic implications

The generally arid Late Triassic climate was interrupted by a wet phase during the mid-Carnian termed the Carnian Pluvial Episode (CPE). Quantitative palynological data from the Mercia Mudstone Group in the Wessex Basin (UK) reveal vegetation changes and palaeoclimate trends. Palynostratigraphy and bulk organic carbon isotope data allow correlation to other Carnian successions. The palynostratigraphy indicates that the Dunscombe Mudstone is Julian and the lowest part of the overlying Branscombe Mudstone Formation is Tuvalian. The Aulisporites acme characterizing the CPE in Tethyan successions and the Germanic Basin is missing in the UK. The quantitative palynological record suggests the predominance of xerophyte floral elements with a few horizons of increased hygrophytes. A humidity signal is not seen owing to the dry climate in central Pangea. Also, the signal might be masked by the overrepresentation of xerophyte regional pollen and the predominance of xerophyte hinterland flora. The bias towards regional pollen rain is enhanced by the potential increase in continental runoff related to seasonally humid conditions and differences in pollen production rates and transport mechanisms. The vegetation of British CPE successions suggests a more complex climate history during the Carnian, indicating that the CPE is not recognized by the same changes everywhere. Supplementary material: A detailed lithological log of the Strangman's Cove (Devon) outcrop with the description of the Mercia Mudstone Group lithostratigraphical units, a description of the laboratory techniques, seven photoplates with selected spores and pollen grains, a list of all identified palynomorphs, Excel sheets with the palynological and palynofacies counts, bulk organic carbon isotope ratios and total organic carbon values of the Strangman's Cove outcrop are available at https://doi.org/10.6084/m9.figshare.c.4138085

Palynological Record of the History of Vegetation in the Sandy Areas of Southern Poland

A palynological analysis was made of the paleosoil (less than 20 cm in thickness) of the age of 4110 ± 110 BP which had formed on the top of river sediments and was subsequently covered with aeolian sands (3.6 m thick) of the so–called Bledow Desert. The results of the palynological analysis indicate: (1) the dominant role of pollen from lime (Tilia) among the tree species; (2) substantial amounts of pollen from maple (Acer); (3) a significant presence of pollen from heather (Ericaceae), and 4) an increase in the contribution of pollen from plants (including grains) associated with human activity. A comparison of data obtained with results from analyzing the contemporary pollen rain in different plant communities of the other parts of Poland indicates that during the formation stage of the Holocene soils in the Bledow Desert, the aforementioned tree species were dominant in the composition of forests and that the presence of a large contribution of pollen from lime and pollen in the soil was determined by their properties and ability to persist in the paleosol.

Vegetation response to exceptional global warmth during Oceanic Anoxic Event 2

The Cenomanian–Turonian Oceanic Anoxic Event (OAE2; ~94.5 million years ago) represents an episode of global-scale marine anoxia and biotic turnover, which corresponds to one of the warmest time intervals in the Phanerozoic. Despite its global significance, information on continental ecosystem response to this greenhouse episode is lacking. Here we present a terrestrial palynological record combined with marine-derived temperature data (TEX86) across an expanded OAE2 section from the Southern Provençal Basin, France. Despite high TEX86-derived temperature estimates reaching up to 38 °C, the continental hinterland did support a diverse vegetation, adapted to persist under elevated temperatures. A transient phase of climatic instability and cooling during OAE2 known as Plenus Cold Event (PCE) is marked by the proliferation of open, savanna-type vegetation rich in angiosperms at the expanse of conifer-dominated forest ecosystems. A rise in early representatives of Normapolles-type pollen during the PCE marks the initial radiation of this important angiosperm group.

Earliest evidence of caries lesion in hominids reveal sugar-rich diet for a Middle Miocene dryopithecine from Europe.

The formation of dental caries is mainly caused by dietary habits and therefore, may contain information for dietary reconstructions of fossil hominids. This study investigates the caries lesion in the 12.5 Ma old type specimen of Dryopithecus carinthiacus Mottl 1957 (Primates, Hominidae) from St. Stefan (Austria). Potential food sources are identified on associated palynological data, which allow conclusions about food quality, sugar availability and the hominid metabolism during the Middle Miocene. Using micro computed tomography (μCT) and scanning electron microscopy (SEM) we provide a detailed analysis and characterization of the individuals’ caries type. Its lesion is compared with a dataset of 311 wild chimpanzees, indicating morphological and etiological differences in caries formation between both species. The affected molar of D. carinthiacus reveals features known from severe dental caries in humans: (1) Cavitation with steep walls and smooth surface; (2) Reparative dentine at the roof of the pulp chamber; (3) Sclerotic dentine below the cavitation; (4) Association with dental calculus and (5) Unilateral usage of the healthy right tooth row. Its advanced primary caries, initiating on the intact enamel surface, indicates a frequent intake of highly cariogenic sugar-rich fruits, which likely exceeds the frugivory of extant chimpanzees. This finding corresponds with the associated palynological record, which infers a habitat with nearly year-round supply (9–10 months/year) of high quality foods (>carbohydrates; < fibers). Our conclusions challenge the model of a step-wise increase in dietary quality during hominid evolution and support the uricase hypothesis, which discusses the hominid autapomorphy of a fructose-based fat accumulation for periods of starvation. This model receives further validation by the identification of soft-tissue preservation, interpreted as fossilized white adipose cells, in the articulated hominid skeleton of Oreopithecus bamboli from Italy.

Ice records provide new insights into climatic vulnerability of Central Asian forest and steppe communities

Forest and steppe communities in the Altai region of Central Asia are threatened by changing climate and anthropogenic pressure. Specifically, increasing drought and grazing pressure may cause collapses of moisture-demanding plant communities, particularly forests. Knowledge about past vegetation and fire responses to climate and land use changes may help anticipating future ecosystem risks, given that it has the potential to disclose mechanisms and processes that govern ecosystem vulnerability. We present a unique paleoecological record from the high-alpine Tsambagarav glacier in the Mongolian Altai that provides novel large-scale information on vegetation, fire and pollution with an exceptional temporal resolution and precision. Our palynological record identifies several late-Holocene boreal forest expansions, contractions and subsequent recoveries. Maximum forest expansions occurred at 3000-2800 BC, 2400-2100 BC, and 1900-1800 BC. After 1800 BC mixed boreal forest communities irrecoverably declined. Fires reached a maximum at 1600 BC, 200 years after the final forest collapse. Our multiproxy data suggest that burning peaked in response to dead biomass accumulation resulting from forest diebacks. Vegetation and fire regimes partly decoupled from climate after 1700 AD, when atmospheric industrial pollution began, and land use intensified. We conclude that moisture availability was more important than temperature for past vegetation dynamics, in particular for forest loss and steppe expansion. The past Mongolian Altai evidence implies that in the future forests of the Russian Altai may collapse in response to reduced moisture availability.

Long-term succession of aquatic plants reconstructed from palynological records in a shallow freshwater lake

Aquatic plants in shallow freshwater lakes play a key role in stabilizing ecological function and providing valuable ecosystem services, yet they are severely degraded worldwide. An improved understanding of long-term aquatic plant succession is critical to investigate the potential driving mechanisms and to facilitate ecological restoration. In this paper, we reconstructed changes in the aquatic plant community over the past century based on palynological records from Changdang Lake, Middle and Lower Yangtze River Basin (MLYB), China. Our results reveal that aquatic plants in Changdang Lake have undergone three clear phases: emergent macrophytes dominated the aquatic vegetation in the 1900s–1970s, submerged macrophytes in the 1970s–1990s, and floating macrophytes increasingly after the 1990s. Significant changes in the aquatic plant communities were caused by increasing anthropogenic pressures, such as damming and nutrient loading from agriculture, aquaculture, and urbanization after the Chinese economic reform. We argue that Changdang Lake is currently in a transition phase between a macrophyte-dominated state and an algae-dominated state. Our palynological record is different from many contemporary studies, which suggest submerged plants dominated most lakes in this region before the 1950s. We suggest that the return of the aquatic plants to their 1970s–1980s state would be a realistic target for lake restoration. Our results show that palynological records can reveal long-term dynamics of macrophytes in shallow lakes for sustainable lake restoration and management.

Evidence of sapropel S1 formation from Holocene lacustrine sequences in Lake Vrana in Dalmatia (Croatia)

The sediment core from Lake Vrana (between 1000 and 500 cm) on the eastern Adriatic coast was analyzed using palynological and geochemical approaches to detect environmental changes during the Holocene. The deepest sediments (between 1000 and 967 cm) in Lake Vrana could correspond to Late Pleistocene to Holocene transition. Although this interval is not dated, it is indicated by the palynological record. After that, the Holocene warming is evident and the observed dark layers are identified as Holocene sapropel S1, known in the eastern Mediterranean (10.8–6.1 cal kyr BP). Sapropelic layer S1a in Lake Vrana sediment core is evident between 905 and 790 cm and it ended at 7.9 cal kyr BP. It is formed in a very shallow freshwater ecosystem, dominated by cyanobacteria Gleocapsa and terrigenous detritus as a consequence of runoff. Periodically anoxic condition occurred. The geochemical signature of sapropelic layer S1a from Lake Vrana is consistent with post-depositional oxidation due to transition to the bottom water oxygenation evidenced in elevated Mn and Mn peak at the end of sapropelic layer S1a deposition. Sapropelic layer S1b, deposited between 7.4 and 6.4 cal kyr BP, is characterized by amorphous organic matter. The two sapropelic layers are separated by the horizon at 7.9–7.4 cal kyr BP, corresponding to the drier climate conditions, indicated by the presence of Poaceae, Ericaceae, Juniperus and Pistacia. This horizon reflects regional climatic cooling associated with reduced levels of precipitation that interrupted a period of generally higher precipitation. Based on geochemical data, Total organic carbon (TOC) and Nitrogen (N), the sapropelic layers are characterized by elevated values comparing to the rest of the core.The new records allow reconstruction of paleoenvironmental changes on land, which give insight into the processes and climate conditions that led to the formation of S1. The evidence indicates that: (i) S1 sapropelic layer in Lake Vrana sediments is an organic-poor deposit; (ii) the S1 period in the study area can be divisible into two sub-phases (S1a and S1b). The key factor that initiated the formation of S1 was increased discharge of freshwater into the Lake Vrana basin during warmer and wetter climate in the Early Holocene.

Centennial-scale vegetation dynamics and climate variability in SE Europe during Marine Isotope Stage 11 based on a pollen record from Lake Ohrid

To better understand climate variability during Marine Isotope Stage (MIS) 11, we here present a new, centennial-scale-resolution pollen record from Lake Ohrid (Balkan Peninsula) derived from sediment cores retrieved during an International Continental Scientific Drilling Program (ICDP) campaign. Our palynological data, augmented by quantitative pollen-based climate reconstructions, provide insight into the vegetation dynamics and thus also climate variability in SE Europe during one of the best orbital analogues for the Holocene. Comparison of our palynological results with other proxy data from Lake Ohrid as well as with regional and global climate records shows that the vegetation in SE Europe responded sensitively both to long- and short-term climate change during MIS 11. The chronology of our palynological record is based on orbital tuning, and is further supported by the detection of a new tephra from the Vico volcano, central Italy, dated to 410 ± 2 ka. Our study indicates that MIS 11c (∼424–398 ka) was the warmest interval of MIS 11. The younger part of the interglacial (i.e., MIS 11b–11a; ∼398–367 ka) exhibits a gradual cooling trend passing over into MIS 10. It is characterized by considerable millennial-scale variability as inferred by six abrupt forest-contraction events. Interestingly, the first forest contraction occurred during full interglacial conditions of MIS 11c; this event lasted for ∼1.7 kyrs (406.2–404.5 ka) and was characterized by substantial reductions in winter temperature and annual precipitation. Most notably, it occurred ∼7 ka before the end of MIS 11c and ∼15 ka before the first strong ice-rafted debris event in the North Atlantic. Our findings suggest that millennial-scale climate variability during MIS 11 was established in Southern Europe already during MIS 11c, which is earlier than in the North Atlantic where it is registered only from MIS 11b onwards.

Stratigraphy of the Northern Pulo do Lobo Domain, SW Iberia Variscides: A palynological contribution

We present palynological results from the northern sector of the Pulo do Lobo Domain, combining sections studied in Portugal and Spain. A total of 139 samples were studied, of which 56 are positive for palynology. The first age determination for the Pulo do Lobo Formation was achieved, indicating a mid-Frasnian age (Verrucosisporites bulliferus and Pustulatisporites rugulatus). The sediments of Peramora Mélange (Spain) yielded the same palyno-assemblage as that of the Pulo do Lobo Fm. and are interpreted as a part of this formation. The Ribeira de Limas Fm. also yielded mid-Frasnian miospore assemblages, indicating the same age as the Pulo do Lobo Fm. The Santa Iria and Horta da Torre formations present spore assemblages assigned to the late Famennian in both Portugal and Spain. The phyllites interbedded with the quartzites of the Alájar Mélange yielded a palyno-assemblage late Famennian in age that can be correlated to the Horta da Torre Fm. Therefore, the Alájar quartzites are interpreted as a lateral equivalent of the Horta da Torre Fm. in Spain. The palynological results obtained for the units of the northern sector of the Pulo do Lobo Domain are highly consistent and in agreement with stratigraphic mapping and structural interpretations. A detailed discussion of the palynological versus geochronological ages based on detrital zircons is included in this study. The palynological results and their comparison with the worldwide Upper Devonian palynological record suggest a close affinity with NW European palynofloras, placing the Pulo do Lobo Domain within the Avalonian paleobiogeographical province.

Palynology of the Morro do Chaves Formation (Lower Cretaceous), Sergipe Alagoas Basin, NE Brazil: Paleoenvironmental implications for the early history of the South Atlantic

The break-up of Gondwana and the origin of related source rocks and reservoir intervals of the Brazilian coastal basins are being increasingly studied in the last decades. In this context the Sergipe-Alagoas Basin, which lies to the north of the Campos Basin hydrocarbon province, becomes relevant for the completeness of its depositional sequences. This paper presents, for the first time, the detailed palynological record from the Morro do Chaves Formation, located at the InterCement Quarry, near São Miguel dos Campos, Alagoas. The analysis of samples from the mudstone intervals of the unit mainly composed by coquinas has enabled new biostratigraphic, paleoenvironmental and paleogeographic interpretations of the evolution of the South Atlantic. The occurrence of the species Dicheiropollis etruscus, with a vertical distribution ranging from the Berriasian to the Barremian, supports the late Barremian age for the lowermost part of the Morro do Chaves Formation, traditionally interpreted as having been deposited in a lacustrine environment, close to herbaceous plants, surrounded by remote mountainous areas with arboreal vegetation. The occurrence of algae phycomata of the Class Prasinophyceae, associated with Scenedesmus and Botryoccocus, organisms that tolerate some salinity in its uppermost part, together with other biotic and abiotic data, corroborate the possibility of relating the Morro do Chaves Formation to a marine and/or brackish depositional environment, which may have resulted from a marine flooding in the northern sector of the Sergipe-Alagoas Basin during Early Cretaceous times. The results of this work support a paleogeographic model characterized by an episodic input of Tethyan waters towards the north of the South American continent.

Implications for conifer glacial refugia and postglacial climatic variation in western Beringia from lake sediments of the Upper Indigirka basin

A c. 13 800 cal. a BP palynological record from Tschuch'ye Lake (eastern Yakutia), when combined with other palaeobotanical records from western Beringia, supports previous conclusions that Larix and Pinus pumila spread from multiple cryptic refugia during the Lateglacial period and middle Holocene, respectively. The antiquity and spatial distribution of Larix in many of these records suggest that full‐glacial landscapes probably had a small but important tree component. The Tschuch'ye record further indicates the absence of a Younger Dryas climatic reversal and is in accord with the preponderance of other data from western Beringia, which indicate warmer than present climates between c. 12 900 and 9100 cal. a BP. The subsequent spread of Pinus pumila, which has similar temperature requirements as Larix, denotes a shift to wetter but still warm climates during the middle Holocene, with palynological data suggesting optimal conditions in far western areas of western Beringia c. 7000–5000 cal. a BP. The postglacial occurrence of relatively warm/dry and warm/wet intervals is consistent with results of a regional climate‐model simulation that indicates warmer than present temperatures and decreased effective moisture at 11 000 cal. a BP and persistence of warm conditions but with greater moisture and longer growing season at 6000 cal. a BP.

Did mangrove communities exist in the Late Cretaceous of the Kristianstad Basin, Sweden?

Previous inferences of oyster-dominated communities occupying mangrove-like depositional settings in the Kristianstad Basin, Sweden, during the late early Campanian are reassessed. A significant percentage of oysters (Acutostrea incurva) from the Belemnellocamax mammillatus zone in Bed 3 at Åsen bear indentations on their left valves indicating attachment to plant axes. Many of these axes bear morphological features characteristic of the distal subaerial portions of woody plant branches and appear to have been rafted into the marine environment rather than representing in situ mangrove stems and roots. Foraminiferal assemblages recovered from sediment within the oyster body cavities differ from modern mangrove-community associations by the absence of siliceous agglutinated Foraminifera, the presence of diverse and relatively abundant Lagenida, relatively common triserial Buliminida, and a notable percentage of planktonic taxa. Chondrichthyan teeth assemblages from the same beds are similarly incompatible with the interpretation of a mangrove depositional environment based on comparisons with the distribution of related extant taxa. Apart from oyster shells and belemnite rostra, these beds are notably depauperate in diversity and abundance of macroinvertebrate remains compared with coeval carbonate shoal and rocky shoreline assemblages from the same basin. The collective palaeontological and sedimentological evidence favours an inner neritic sandy-substrate setting, but not nearshore or mangrove-like depositional environment for the oyster-rich Bed 3 at Åsen. The absence of mangrove-like assemblages at Åsen is consistent with the development of modern mangrove ecosystems much later (during the Maastrichtian and Cenozoic) based on the global palynological record.

The Quaternary plant fossil record from the volcanic Azores Archipelago (Portugal, North Atlantic Ocean): a review

Plant fossils are known from the Azores Islands, yet poorly studied. We present a comprehensive bibliographical review for the archipelago. A first pre-scientific reference dates from late fifteenth century, while the first scientific description was reported in 1821, accounting for trunks in pyroclastic units and silicified plants within hydrothermal deposits. Throughout the second-half of the nineteenth century and the first-half of the twentieth century, prospection by naturalists and geological mapping work, led to the discovery and description of plant fossils in most islands. From the 1970s onwards, the taxonomic interest ceased, and plant fossils were used mainly for 14C dating. Recently, sediment cores from lakes and peatlands were used for palaeoecological reconstructions and to measure anthropogenic impacts. Generally, plant fossils are younger than 50 ka, although older fossils may exist. Azorean plant fossils include somatofossils of leaves, stems, logs and seeds preserved as impressions, compressions, adpressions, permineralizations, lava tree casts and mummifications. The taphonomy of macrofloral elements is usually related to explosive volcanic activity, while palynological record is associated with lake sediments and peat bogs. The persistence in palaeobotanical and palaeopalynological studies will decisively contribute to disentangle the paleodiversity, palaeoecology, and add crucial information on insular plant phylogeny and biogeography.

Holocene vegetation and climate evolution of Corpus Christi and Trinity bays: Implications on coastal Texas source-to-sink deposition

The Texas coastline stretches 595km across almost 4° of latitude and is home to diverse coastal vegetation assemblages, yet only a handful of studies have documented the climate and vegetative change of this region through the Holocene. We provide a detailed palynological record of Holocene climate for coastal Texas, based upon three subaqueous sediment cores from Corpus Christi Bay and Trinity Bay. Cluster analysis and correspondence analysis were used to investigate changes in palynological assemblages through time within each core. Common to both bays are nonarboreal taxa including Asteraceae (mainly Ambrosia and Helianthus), Chenopodium, Poaceae, and arboreal taxa such as Carya, Pinus, and Quercus. Our record shows that the coastal environments of central Texas began a transition from herbaceous (nonarboreal) dominated vegetation to arboreal vegetation as early as 8.4ka within Corpus Christi Bay, and 3.8ka within Trinity Bay. We note flooding events at 8.2, 5.4, and 3.6ka in Corpus Christi Bay, and at 1.7, 1.2, and 0.8ka in Trinity Bay. These events were caused by storms, sea level changes including flooding of relict river terraces, and changes in sediment delivery to the bays. The pollen record also shows evidence for changes in fluvial discharge to Corpus Christi Bay at 4.1 and 2.2ka, and at 1.8ka in Trinity Bay. We also see Zea mays in Trinity Bay, indicating local Native American agriculture. We observe no significant changes during the middle Holocene Climatic Optimum, and subtle but not statistically significant evidence of more variable climate oscillations than other records from more interior sites in Texas available for the late Holocene. This indicates that coastal Texas’ climate has operated semi-independently from central Texas regions, and was primarily driven by a coast-wise gradient of precipitation and evapotranspiration.