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Topics and sessions > Topic VIII - Type of lake: synthesis and advancesVIII-1-Tectonics, climate, ecology and geomorphology in rift lakesConveners
From deep-water long-lived lakes like Lake Tanganyika in the western East African Rift Valley (Neogene-Quaternary) to shallow rift lakes like those in France from the Paleogene, the sedimentary records of rift lakes can preserve 100s of thousands to even millions of years of evidence for changing climate and ecology. The long successions also inform us about tectonics, volcanism, and geomorphology as they relate to heat sources, erosion, sediment input, and lake-dam barriers due to volcanic flows. The dynamic balance between these factors ultimately determines lake chemistry, response to climate variability, authigenic and clastic facies compositions, (paleo)ecology, and stratigraphy. This session aims to explore the interplay between these major controls on extant rift lakes and ancient rift lake successions, with a focus on recognizing their variable influences and changing impacts through time.
VIII-2-Mountain lakes from extreme environments Conveners
Located away from human activities, mountain lakes in remote regions represent some of the least disturbed ecosystems in the world. In addition, these environments are extremely sensitive to global climate changes. Recent studies have shown that these ecosystems are crossing ecological thresholds in terms of physical, chemical and ecological states not previously observed. With the recent warming and projected trajectories of environmental change, lake records from remote areas are crucial to better understand how human activities and climatic changes impact the functioning of these ecosystems in order to make better decisions about the future in Earth. We welcome paleolimnological as well as contemporary limnological contributions at different time scales that supports the vision that remote lake ecosystems are excellent and unique sentinel ecosystems of global change.
VIII-3-Coastal lakes and lagoons: archives of past extreme-wave event, climate and environmental variations Conveners
Even if coastal lakes and or lagoons systems are a less studied environmental archives compared to other lacustrine systems, they provide valuable information on the reconstruction of rapid environmental changes under both terrestrial and marine forcing. Depending on their geomorphology (more or less connected to the ocean) and climate context (from tropics to high latitudes), many challenges are particular to this lacustrine system such as marine influence, high bioturbation, shallow water, evaporation or seasonal variation in salinity. In this session we encourage the presentation of studies on sediment in coastal lakes or lagoons to extract varying information at a range of different timescales (decadal to millennial) from marine submersions (tsunami, storm surge), sea-level fluctuations, anthropogenic impacts and climate variations (wet/dry periods) to ecological dynamics and water quality, with a focus on past geodynamic, climate and/or environmental forcing.
VIII-4-Lake Bourget and cousins: perialpine lakes as the cradles and future of limnogeology and paleolimnology Conveners
The specific shape of European Alps led to the onset of flexural basins both in front (west and north sides) at the back (east and south sides) of the chain. Subsequent geodynamics and glaciations maintained overdeepened basins pinched between the main chain and the foreland ones on the west and north sides and the vaster Po flexural basin on the east and south sides. During Quaternary interglacial periods those structural depressions are filled with waters giving bith to chaplet of lakes, the so-called perialpine lakes. Theses lakes’ sedimentary infilling present the particularity to be composed of a autochthonous carbonate fraction more or less diluted by the products of the Alps erosion, generally leading to the construction of massive deltas at the tributary outlets and to the deposition of hyperpycnites in the deeper basins. This particularitiy make them model scales of oceanic basins that attracted sedimentologists as early the 60s’. Nowadays those lakes continue to be under the scope of the limnogeologists and paleolimnologist questionning a renewed bunch of scientific questions and revisiting old ones with fresh ideas and groundbreaking new tools. With this session we aim at celebrating more than 50 years of scientific investigations of perialpine lakes since the pioneer works by the legends of our discipline up to the very latest developments. We hope to bring together key contribution by and about pioneers as well as by the vanguard of the generation of researchers. Any topic that can be treated using perialpine lake sediment is welcomed, as well as any technical approach from biology-based up to geophysics, including all the geochemists quiver of techniques. Depending on the success of this call-for-abstract, some contributions could be transformed into a dedicated short-course session prior or after the congress itself.
VIII-5-Deep-time carbonate-rich lacustrine systems Conveners
With recent significant progress taking place in the study of ancient continental carbonates and the understanding that they are represented by diverse and complex facies associations, we have thought about bringing the continental carbonate working community together. Lacustrine carbonates record the interplay of several biological, physical, and chemical factors acting at different time scales, embracing very different aspects, from the microbiota crucial role in autochthonous precipitation up to sediment delivery load to the paleolake. Such interactions make them a robust tool of reconstruction of ancient lake basins, particularly from deep-time geologic records. Recent advances include refining the understanding of the role of groundwater in carbonate-rich paleolakes precipitation and the standardization of carbonate-rich palustrine facies associated with lacustrine systems; also, the modelling of paleoclimate trends from geochemistry proxies from continental carbonates. Detailed characterization of some climate milestones is also possible through multiproxy approaches. Because we acknowledge the complexity of these systems we would like to invite colleagues to share contributions about any aspects of ancient carbonate-rich lake basins such as sedimentology, mineralogy, geochemistry, paleontology, and their geodynamic context. Both single- and multiproxy studies, spanning different scales, are welcome. The session is conceived to encompass studies on fluvio-deltaic-lacustrine, palustrine and wetland subenvironments as well; and a variety of facies associations, including those formed in saline conditions. We encourage contributions focused in the obstacles encountered too, to bring interesting discussions on how to move forward in the discipline. Recent carbonate lacustrine system contributions will be accepted if they pinpoint keys to improve ancient lake basin understanding, such as modern analogues for particular processes or subenvironments.
VIII-6-Imprints of natural and anthropogenic environmental changes in crater lakes Conveners
Crater lakes hold important value as sites of cultural heritage and geoheritage. These unique aquatic ecosystems can also provide a valuable window into environmental transitions at both local and global scale. Due to their distinctive morphology, these closed systems have the potential to accumulate continuous, high-resolution records of environmental variability. Yet others are highly volatile systems bearing evidence of abrupt environmental changes. This session invites a wide variety of contributions discussing natural or human imprints in the physicochemical or biological features of the water column and/or the sedimentary record of crater lakes. Potential topics include, but are not limited to, patterns and consequences of climate variability – from long-term trends to short-term fluctuations and from recent times to the distant past – as well as of a suite of human perturbations affecting these peculiar systems. The session is open to research contributions drawing on paleolimnological time-series, modern observation, experimentation or modeling, and welcomes especially research integrating multiple approaches.
VIII-7-Current and past lakes in planetary bodies of the solar system, and their terrestrial analogues on Earth Conveners
This session will cover the geomorphology, sedimentology and physico-chemical environment of lakes in planetary bodies of the solar system, namely on Mars and Titan. We welcome studies on Mars focusing on paleolakes and their environment of deposition from orbital or in-situ rover data, as well as those focusing on current subglacial lakes. Studies on Titan can include space probe data analysis or theoretical studies on chemical species present in current lakes. We also welcome studies on planetary analogues on Earth that would bring to light on some of the landforms observed on planetary bodies.
VIII-8-Arctic paleolimnology across permafrost « limnoscapes » Conveners
Lakes and ponds are extremely abundant in high latitude regions, especially across Arctic permafrost landscapes which are in rapid transition in response to climate change. These freshwater ecosystems act as unique environmental sentinels, integrating and recording environmental changes – past and present – in their basins and bottom sediments, providing information on thermokarst and other processes occurring in their surrounding catchments. This session aims at bringing together paleolimnologists working or interested in high latitude permafrost « limnoscapes », over timescales from the recent past to the entire Holocene and beyond. Presentations from all fields of Arctic paleolimnology are welcome, including physico-chemical investigations of lacustrine archives to biostratigraphy, as well as remote sensing and modelling studies. The session will focus on presenting the current state-of-the-science and fostering exchanges between researchers examining all aspects of lake and pond ecosystem processes and dynamics over various time spans and across widespread geographic regions of the circumpolar North.
VIII-9-Linking varved sediment records to changing lake systems Convenor
Varves, annual laminations deposited at the bottom of lakes, can reflect past changes through their physical and chemical composition as well as through microfossil assemblages preserved in the seasonal layers. Each lake system is unique and the high temporal resolution, over centennial and millennial scales, enables linking processes mediating past changes within the lake system and its catchment with varve composition. The varved record provides, thus, information on forcing factors such as climate conditions, evolution of the local landscape and anthropogenic impacts. This session welcomes scientific contributions that investigate varved records, from short-term monitoring to long-term reconstructions, to understand how lakes and regional environments responded to external forcing. This session is organized by the Varve Working Group (PAGES) and aims to discuss varved records from diverse lake systems and illuminate the potential of varve research to inform adaptation strategies and mitigate adverse climatic or environmental changes.
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