Chronology Of Deposits Research Articles

Continental-scale drainage reorganization during Mesoproterozoic orogenesis: Evidence from the Belt Basin of western North America

The Mesoproterozoic Belt Basin of the northwestern United States and southwestern Canada contains a 5–20-km-thick metasedimentary succession deposited during an important transition in the Precambrian development of North America. Key unresolved issues for the Belt Basin include the chronology of deposition, sources of siliciclastic sediment, and regional paleogeography during Laurentian orogenesis. To address these topics, we acquired detrital zircon U-Pb geochronologic data for eastern exposures of the Belt-Purcell Supergroup in the Lewis thrust salient along the USA-Canada border. To define an integrated chronostratigraphic and provenance framework for the Belt Basin, we calculated maximum depositional ages and qualitatively and quantitatively compared our geochronologic data set to a compilation of Laurentian igneous and metamorphic zircon U-Pb ages using multidimensional scaling and an inverse Monte Carlo model. The results suggest a stratigraphic age range of ca. 1495–1380 Ma, constituting a depositional duration of ~115 m.y. with an average sediment accumulation rate of ~40 m/m.y. for the studied locality (extrapolated to ~155 m/m.y. for the basin depocenter). Variations in sediment provenance are expressed by three distinct intervals within the Belt-Purcell Supergroup. The lower Belt Supergroup succession (Waterton to lower Helena Formations; ca. 1495–1440 Ma) is dominated by Paleoproterozoic and Archean grains derived from the northeastern Canadian Shield. The middle Belt Supergroup succession (upper Helena to Sheppard Formations; ca. 1440–1420 Ma) displays mixed early Mesoproterozoic, late Paleoproterozoic, and Archean zircon age groups. The upper Belt Supergroup succession (Gateway to Roosville Formations; ca. 1420–1380 Ma) contains almost entirely late Paleo-proterozoic zircons sourced from the south (Yavapai-Mazatzal and Mojave crustal provinces). We interpret sediment provenance to reflect a continental-scale, fluvial drainage reorganization during middle Belt Supergroup deposition that can be linked to the recently recognized Picuris orogeny.

First insights into the age of the giant ice deposits in the Eisriesenwelt cave (Austria)

Frozen water is the most widespread type of ice present in ice caves and forms ice stalagmites and stalactites as well as floor ice, which is often several meters thick. Organic macroremains are commonly rare in this type of cave ice, which makes it difficult to establish a chronology and severely limits the use of such ice deposits as paleoenvironmental archives. Here, the chronology of such ice deposits in the inner part of the glaciated Eisriesenwelt, one of the world’s largest ice caves located in the European Alps of Austria, is determined by a combination of radiocarbon and 230Th dating of cryogenic calcite. The data suggest that this cave ice has formed over the last three millennia, with a marked increase in the average accumulation rate during the thirteenth century, coinciding with the onset of the Little Ice Age in the Alps. Data from a second site closer to the entrance suggests that large parts of this tourist cave were likely ice-free during the Medieval Warm Period and that a substantial part of the ice is probably a relic of the Little Ice Age. The current warming has already penetrated deeper into the cave than during the Medieval Warm Period, although air exchange during the warm season is restricted by a door at the cave entrance.

Development and chronology of the Late Jurassic shallow-water carbonate deposits of the Holy Cross Mountains area, central Poland

The Late Jurassic shallow-water carbonates with intervening clayey-marly deeper-water deposits in the Holy Cross Mts. area formed over large bank of the elevated part of the Northern Tethyan Shelf during about 12 myr. They comprise three main successions (I, II and III) deposited partly in different environmental conditions, controlled by tectonic and climatic factors, and still preserved in the north-eastern margin, the north-western margin and the south-western margin of the Holy Cross Mountains. The history of sedimentation is presented according to the concept of the large tectono-stratigraphic units COK, LUK and KVB, which owe their origin to variable rates of tectonic subsidence, as introduced by Kutek (1994) for the area of central Poland. The studied deposits of the COK megasequence corresponding to the Upper Oxfordian and the Lower Kimmeridgian up to the Hypselocyclum Zone consist of coral limestones, various grained (including oolitic) limestones, and micritic limestones formed over the gradually enlarging shallow-water carbonate platform of the Holy Cross Mts. This platform was subsequently subdivided into two elevated areas, separated by a depressed zone in the middle, bounded by the Nowe Miasto–Iłża–Bałtów Fault Zone in the north-east and the Holy Cross Fault System in the south. The younger megasequence LUK with it strongly transgressive character marks the successive stages of the marine transgression which entered the central, lowered part of the area of the Holy Cross Mts. from the west, where it appeared already in the early Hypselocyclum Chron. It successively spread across the Holy Cross Mts. area towards the north-east and south bringing everywhere the deposition of various oyster lumachelles and marls with ammonites at the end of the Hypselocyclum Chron and during the Divisum Chron of the Early Kimmeridgian to the Acanthicum/Mutabilis Chron of the earliest Late Kimmeridgian. The following megasequence KVB is represented by the detrital lumachelles and chalky limestones with nereineids of the Eudoxus Chron of the Late Kimmeridgian marking the development of still younger shallow-water carbonate platform in the uplifted areas in the north-eastern and possibly the south-western margins of the mountains, allegedly subdivided by a deeper area of sedimentation of marly deposits. The youngest Late Jurassic deposits of the Holy Cross Mts., are very fragmentarily preserved, mostly because of Early Cretaceous uplift and erosion. They suggest an initial episode of complete drowning of the carbonate platform which became covered by marly deposits during the Early Tithonian, and the subsequent restoration of shallow-water carbonate sedimentation at the end of the Early Tithonian.

Penelusuran sisa-sisa Kerajaan yang hilang dibalik Letusan Gunung Tambora di Situs Doro Bente

The archaeological research in the Tambora Peninsula was initiated by the National Archaeological Research Center in 2006, and from 2008 onwards, it was continued by the Archaeological Office in Denpasar-Bali until 2021. Numerous archaeological pieces of evidence have been successfully excavated from Mount Tambora's pyroclastic material. Recent research has been focused on the Doro Bente Site on the Teluk Saleh Peninsula. The research aims to understand the sequence of historical events on settlement centers based on artifact evidence resulting from the eruption of Mount Tambora in 1815. The study employs qualitative, descriptive methods, and a geoarchaeological approach. Data acquisition involves excavation, surveys, and literature studies. Stratigraphic analysis is conducted to identify sediment matrices and understand the deposition sequence. Excavation activities have uncovered significant artifacts such as ceramic fragments, pottery, animal bones, and shell fragments. Micro-scale deposition chronology in excavation box B28U18 indicates that the three lower layers, the oldest, were deposited in a marine environment, followed by five layers of pyroclastic material from the 1815 eruption of Mount Tambora. The geographical factors and available natural resources make Sumbawa Island a focal point for Chinese and European attention from the 13th to the 19th centuries AD.

Last Glacial loess in Europe: luminescence database and chronology of deposition

Abstract. During the Last Glacial Period, the climate shift to cold conditions associated with changes in atmospheric circulation and vegetation cover resulted in the development of large aeolian systems in Europe. On a regional scale, many factors may have influenced dust dynamics, such as the latitudinal difference between the various aeolian systems and the variability of the sources of wind-transported particles. Therefore, the assumption that the timing of aeolian deposition is strictly synchronous in Europe does not seem to be the most plausible hypothesis and needs to be evaluated. To test this assumption, the chronology of loess deposition in different European regions was investigated by studying 93 luminescence-dated loess–palaeosol sequences with their data recalculated and compiled in a single comma separated values (*.csv) file: the ChronoLoess database. Our study shows that the two major aeolian systems, the Northern European Loess Belt (NELB) on the one hand and the systems associated with the rivers draining the Alpine Ice Sheet on the other hand, developed asynchronously. The significant deposition started at about 32 kyr b2k for the NELB vs. 42 kyr b2k for the perialpine loess and peaked about 2 millennia later for the former (21.8 vs. 23.9 kyr b2k, respectively). This shift resulted mainly from the time lag between the maxima of the Alpine and Fennoscandian ice sheets, which acted as the primary sources of fine-grained particles through glacial abrasion. The major geomorphic changes that resulted from the development and decay of the Fennoscandian and British–Irish ice sheets also played an important role. Particularly, ice sheet coalescence during the Last Glacial Maximum (LGM) diverted meltwater fluxes through the Channel River and provided vast amounts of glacial particles available for deflation in the western NELB. The period during which the maximum mass accumulation rate was reached for each loess–palaeosol sequence is relatively homogeneous in the NELB and ranges from 30 to 19 kyr b2k, whereas it is more scattered in the perialpine systems (>60 to 14 kyr b2k). This probably resulted from a combination of factors, including the asynchrony of maximum valley glacier advances and local geomorphic factors. The ChronoLoess database is available at https://doi.org/10.5281/zenodo.7728616 (Bosq et al., 2023).

Background Tests and Improvements at LAC-UFF Aiming at Sample Size Reduction in Foraminifera 14C Measurement

Foraminifera are widely used in paleoclimatic and paleoceanographic studies, providing information about past ocean conditions. However, in order to use these tracers, it is essential to obtain an accurate chronology. Radiocarbon has proven to be a powerful tool in developing robust chronologies. Sample sizes of a few milligrams of carbonate material are needed for precise radiocarbon determination using accelerator mass spectrometry (AMS). In the specific case of paleoceanographic and paleoenvironmental studies, Foraminifera microfossils are the most important indicator of oceanic conditions. However, for establishing the chronology of deposition, sample availability is often limited. In AMS facilities using solid ion sources, such as the Radiocarbon Laboratory of the Universidade Federal Fluminense (LAC-UFF), in Brazil, CO2 samples need to be converted to graphite after physical and chemical pre-treatment to remove contamination. Reducing the sample sizes increases the relative contribution of contamination and can favor increased background levels. In this work, we tested different amounts of 14C-free carbonate samples as a means to evaluate the pattern of contamination. For the sealed tube Zn/TiH2 graphitization method, we tested prebaking the graphitization tubes and compared storage procedures. As a result, the background for regular-sized samples was decreased, and accurate measurement of carbonate samples containing ca. 0.5 mg C could be performed. Prebaked graphitization tubes can safely be stored in desiccator cabinets for up to 4 weeks. Foraminifera samples with mass as low as 1 mg (ca. 0.1 mg C) can now be measured at the LAC-UFF AMS facility, provided that C contamination can be estimated and corrected. The developments presented in this work allowed for the study of species-specific Foraminifera and other small-sized carbonate samples.

A long-term context for the 1663 Charlevoix CE earthquake interpreted from the postglacial landslide record in the Gouffre Valley, Quebec, Canada

This paper examines the distribution, stratigraphy and chronology of landslide deposits within the Gouffre Valley to provide a long-term context for the 1663 CE M 7.0–7.5 Charlevoix earthquake, Charlevoix-Kamouraska Seismic Zone (CKSZ), southern Quebec, Canada. Our mapping utilized a 1 × 1 m digital terrain model, and we interpreted deposit age and stratigraphy from 30 new AMS radiocarbon ages, supplemented by 51 regular radiocarbon ages and 23 dendrochronology ages compiled from previous studies. These data provide a robust chronological connection between the 1663 CE earthquake and large-scale landslide deposits that cover about 24 km2, extend about 20 km along the valley bottom, and originated from separate source areas. Eight, relatively small-scale (less than 0.48 km2), prehistoric landslide features are also present in the Gouffre Valley, including three dated landslides, aged between about 7950–7300, 6595–6087, and 1310–1200 cal BCE, a poorly-constrained deposit aged between 4782–4452 BCE and 1663 CE, and four landslides of unknown age. There is no evidence to support an earthquake trigger for any of these prehistoric landslides. Instead, the widespread deposits associated with the 1663 CE earthquake represent the only multi-event, landslide signature in the Gouffre Valley. This, in combination with a long gap between early postglacial and late Holocene mass movement activity in several nearby lakes, is consistent with the 1663 CE earthquake being the largest to occur in the CKSZ over the past about 10 ka.

ESTATES OF THE MOSCOW NOBILITY OF THE 14th–15th CENTURIES IN THE PODOL (LOWER AREA) OF THE MOSCOW KREMLIN

The article provides a preliminary general description of the results of archaeological studies in wet cultural layers in the Tainitsky Garden of the Moscow Kremlin in 2020. The materials collected during the excavations are of exceptional interest for studying the stratigraphy and chronology of cultural deposits in Podol (lower) area and provide a rare opportunity (for the case of the Kremlin) of dating individual structures dendrochronologically. Moreover, the material adds considerable new evidence on the culture of Moscow and the social image of the owners of the Kremlin estates of the 14th–15th centuries AD. The construction in the investigated section of the Podol area since the middle of the 14th century AD was dense and the size of the estates is unknown. The inventory of found artefacts of the period under consideration contains both everyday household objects common for urban use and items associated with a prestigious lifestyle and military activities. Estates of the middle – second half of the 14th century AD can be considered as part of the Kremlin households of Timofey Vasilyevich Velyaminov or his closest relatives.

Middle Miocene paleoenvironmental change and paleoelevation of the Lunpola Basin, Central Tibet

The Tibetan region underwent diachronous differential rises during the Cenozoic era. Its elevation history is critical for understanding the processes of mountain building, and for evaluating its climatic effects on atmospheric circulations. However, knowledge of paleoenvironment and paleoelevation in different geological domains of the Tibetan Plateau is still limited. Here we provide chronology of lacustrine deposits of the Upper Dingqing Formation in the Lunpola Basin in Central Tibet, which yields a middle Miocene age (15–12 Ma). Both stable isotope and palynological records indicate a climatic transition at ∼13.8 Ma marked by a change towards a cooler and drier climate after the Middle Miocene Climate Transition driven by global climatic cooling. Pollen and spore assemblages suggest that the vegetation was dominated by mixed coniferous–broadleaved forest with some grasslands. New palynological elevation reconstructions constrained by the co-existence approach yield a maximum paleo-elevation of 3100–3600 m (average 3350 m) of the Lunpola Basin, which was consistent with a maximum elevation of 3400 m based on floating-leaf plants. Our new data do not support previous views that the Lunpola Basin achieved its current elevation as early as the late Eocene or early Oligocene, but instead we suggest there has been a rise of up to 1200 m since 12 million years ago. Our results bring new light on both the paleoenvironmental reconstructions and the paleo-elevation estimates of the Lunpola Basin, Central Tibet.

Targeted radiocarbon dating of animal bones from ritual wetland depositions in early Iron Age (Denmark)

The biography and chronology of ritual wetland deposits of animal bones has proven difficult to establish and has been based on the study and typology of associated groups of objects (ceramics and weapons) deposited at the same site. As a result, animal bone deposits are often generalised and perceived in plural, even though several sites exhibit evidence of multiple, clearly separate deposits of individual animals or animal parts. To surmount these shortcomings, this study presents and discusses the results of targeted radiocarbon dating of animal bone depositions from a number of well-established ritual wetland sites dated to the early Iron Age within the area of present-day Denmark. The study includes 154 radiocarbon dates from 10 different sites. The results confirm that the biography of ritual animal bone depositions in wetland sites is highly complex and indicate that the use of wetlands during the early Iron Age for ritualized deposition of animal bones lasted for up to 800 years from the 4th – 5th century BC. The study also shows that domestic animal species were preferred over wild animals, and it confirms that some species may have held a special significance. It is further suggested that some animal species were deposited in wetland ritual depositions for a longer period of time than others, and that some wetland sites were in use through multiple centuries, whereas others were not. All in all, the study suggests a complex and dynamic use of wetlands and animals as part of early Iron Age ritual life.

Luminescence chronology of fluvial and aeolian deposits from the Emirate of Sharjah, UAE

AbstractQuaternary environments on the Arabian Peninsula shifted between pronounced arid conditions and phases of increased rainfall, which had a profound impact on Earth surface processes. However, while aeolian sediment dynamics are reasonably well understood, there is a lack of knowledge with regard to variability in the fluvial systems. Presented here are the findings from several locations within wadi drainage systems to the west of the Hajar Mountains (United Arab Emirates). The performance of optically stimulated luminescence dating using a customized standardized growth curve approach is investigated, showing that this approach allows reliable determination of ages by reducing the machine time required. Three main periods of fluvial activity occurred at 160–135, 43–34, and ca. 20 ka. Additional ages fall into the latest Pleistocene and Late Holocene. None of the ages coincides with major wet periods in SE Arabia that have been identified in stalagmites and by the deposition of lake sediments. It is shown that fluvial activity was partly contemporaneous (within the given time resolution) with phases of aeolian deposition and was almost continuous, but likely sporadic, during the Middle to Late Pleistocene. This highlights the need for regionally defined paleoenvironmental records to fully understand the response of dryland systems to long-term climatic change.

Deposition chronologies in a peat bog from Spitsbergen (High Arctic) using the 210Pb dating method

Deposition chronologies in a peat bog from Spitsbergen (High Arctic) using the 210Pb dating method

Chronology of Coastal Alluvial Deposits in The Ria de Coruña (NW Spain) Linked to the Upper Pleistocene Sea Level Regression

The Ria de Coruña (NW Spain) is a wide estuary recently formed by the flooding of the Mero fluvial valley lowlands during the last postglacial transgression. During the last glacial episode, with the sea level located more than 100 m below the current one, the final section of the Mero river and lateral tributaries contributed numerous deposits that the postglacial rise in sea level has partially flooded. Until now, the presence of these alluvial deposits disconnected from the main network by the Holocene marine transgression had been misinterpreted, especially for lack of an absolute chronology that would place them in an adequate paleoclimatic context. For the first time, a deposition age was assessed in this work by optically stimulated luminescence (OSL) dating back from 128 ka to 51 ka.

Robust prestack seismic facies analysis using shearlet transform-based deep learning

Abstract One of the primary purposes of seismic stratigraphy is to evaluate the components of seismic layer relationships within a depositional chronology. Prestack seismic images contain a wealth of information, such as variations in the offset and azimuth of a seismic event, and naturally produce higher-resolution seismic facies analysis results than poststack data. However, prestack data usually suffer from potential unreliability issues due to low signal-to-noise ratios. As this is often overlooked, the present facies analysis methods sometimes fail to extract accurate features from prestack images, which inevitably influences the facies analysis results. To address this issue, this article provides a robust data-driven technique for extracting offset-temporal features via shearlet transform-based deep convolution autoencoders (STCAEs). Unlike the present facies analysis in the time domain, STCAE can optimally represent prestack images at multiple scales and directions through the two-dimensional shearlet transform, which preserves fine edges while suppressing noise in prestack images. Subsequently, robust features are extracted from prestack images in a data-driven manner through a contractive convolutional autoencoder network. We compare our method with other advanced methods and demonstrate the advantages of the proposed approach in classifying seismic layers in prestack data.

High resolution luminescence chronology of coastal dune deposits near Chumphon, Western Gulf of Thailand

The development of coastal dunes is linked to environmental controls such as sea-level variability, climatic conditions, and coastal morphology. Understanding the spatial and temporal variations of dunes is crucial for predicting how coastal landscapes may react to future climate changes and sea-level rise. However, there are very few detailed studies on the longer time-scale evolution (centennial to millennial) of coastal dunes from subtropical and tropical regions. Here, we combine a high-resolution luminescence chronology with sedimentological analyses to study the depositional history of a transverse coastal dune located within the Bang Berd dune field, Western Gulf of Thailand. While luminescence dating of uniform aeolian deposits is normally straight forward, we observe strong variations in the natural dose rate which are likely explained by the enrichment of accessory minerals in some laminae. Deposition of the dune started at least around 3000 years ago and coincides with a regional sea level drop. Sedimentary structures indicate deposition occurring predominantly in relation to the northeasterly winter monsoon. As the sea-level rise and increased storm intensity in the future may lead to stronger erosion along the coast, this study is highlighting the importance of the Bang Berd dune system as natural protection against coastal inundation.

Luminescence chronology of loess-palaeosol deposits in the Central Shandong Mountains region: Provenances and paleoclimate implications

The loess-palaeosol deposits of the Central Shandong Mountains (CSM) to the east of the Chinese Loess Plateau (CLP) potentially provide valuable archives for the reconstruction of East Asian monsoon patterns. However, compared to the abundant attention given to the loess layer, fewer studies have explored the palaeosols documenting the processes and characteristics of interglacial climate changes. The high-resolution chronologies and provenances of the palaeosol in the CSM area are still unclear. In this work, the luminescence ages and paleoclimate proxies in the Shaozhuang (SZ) and Focun (FC) sections were studied, by combining detrital zircons U–Pb ages from the loess-palaesosol in Jingbian, Licheng, Focun, Pianguan and Dongming Yellow River sediments. Quartz single-aliquot regenerative dose protocol (SAR) and K-feldspar post-infrared IRSL (pIRIR 290 ) dating results were obtained in the SZ (8.0 ± 1.1 ka −50.8 ± 2.7 ka) and FC (3.8 ± 0.3 ka—144.0 ± 7.8 ka) sections to develop the most detailed CSM region chronologies to date. The analyzed grain sizes and detrital zircon U–Pb ages suggest that the provenance of the CSM loess was dominated by local Yellow River sediments. The palaeosols observed in the field in these two sections were composed of both aggradation soils deposited in the interglacial period and non-aggradation soil formed by the weathering and leaching of the underlying loess. We found evidences for the presence of non-aggradation soils as indicated the relatively high 5–16 μm particle percentages, relatively low chemical index of alteration (CIA) values and the percentages of >63 μm particles compared to those of the overlying palaeosol layers. Nevertheless, the loess-palaeosol deposits in the CSM are still the product of the East Asian monsoon and global climatic variations, as the deposits have recorded the glacial-interglacial cycles.

Luminescence dating reveals a rapid response to climate change of fluvial terrace formation along the Ani River, northeastern Japan, during the last glacial period

Fluvial terraces along the middle reaches of many Japanese rivers were formed during the last glacial period as a result of changes in sediment discharge related to cooler temperatures and/or reduced water discharge because of lower precipitation. The influence of climate change on these fluvial terraces is not yet fully understood because most previous studies lacked detailed reconstructions of the chronology of terrace development. This study provides a detailed luminescence chronology of fluvial terrace deposits along the Ani River, northeastern Honshu, Japan, and compares that chronology to paleoclimatic records. Eight samples for luminescence dating were obtained from an outcrop of terrace deposits (∼10 m thick) in the Ani River valley. The fading-corrected infrared stimulated luminescence (IRSL) ages are consistent with the fading-corrected post-IR IRSL ages for some samples, which suggests that fading corrections were effective despite the higher fading rates of the IRSL signal. However, for the other samples, the post-IR IRSL ages are significantly older than the fading-corrected IRSL ages due to incomplete bleaching. The pulsed IRSL signals are close to field saturation for older samples, which might have resulted in a greater variation of the ages. Fading-corrected IRSL ages demonstrate periods of rapid aggradation during 105–90 ka and 75–60 ka. Comparison of terrace development with paleoclimatic records indicates that the two periods of fluvial deposition correspond to decreases in precipitation caused by weakened East Asian summer monsoon precipitation and possibly decreases in temperature. The results of this study show that the Ani River responded rapidly to climate change on a time scale of a few tens of thousands of years during the last glacial period.

ESR dating of optically bleached quartz grains from Plio-Pleistocene to Holocene coastal dune deposits (Wilderness-Knysna area, South Africa): a comparison with luminescence

Five Plio-Pleistocene to Holocene aeolian quartz samples from the coastal dune deposits of the Wilderness-Knysna area (South Africa) previously dated by OSL were selected for ESR dating. Samples were processed following the Multiple Centre approach and using the Multiple Aliquot Additive dose method. Aluminium (Al) and Titanium (Ti) signals were systematically measured in all samples. Our study shows that ESR results obtained for Middle Pleistocene to Holocene samples may be strongly impacted by (i) the presence of a significant high frequency noise in the ESR spectra acquired for the Ti signals and (ii) the choice of the fitting function employed. In particular, if not taken into account, very noisy spectra can lead to a significant overestimation of the true ESR intensity measured for the Ti–H signal. These sources of uncertainty are however not sufficient to remove the ESR age overestimations. Consequently, our results indicate that the Al and Ti ESR signals of these quartz samples have not been fully reset during their aeolian transport. While this work contributes to improve our understanding of the ESR method applied to quartz grains, and especially of the potential and limitations of the Ti signals, it also provides additional baseline data to illustrate the existing variability among quartz samples of different origins or sedimentary context. Our results are consistent with previous studies by confirming that the Ti–H signal shows the best potential for the evaluation of low dose values (<100 Gy for these samples), whereas it becomes inappropriate for the higher dose range, and the Ti–Li–H (option D sensu Duval and Guilarte, 2015) should be used instead. Beyond the methodological outcome, this ESR dating study also provides a useful addition to the existing chronology of the aeolian deposits in this region. In particular, new (and possibly) finite numerical age results were obtained for the two oldest samples, constraining the aeolianite landward barrier dune and the coversand formations to the MIS 10-8 and Pliocene, respectively.

Professor Kenneth John Gregory (1938–2020): The career, contributions and legacy of an eminent geographer and fluvial geomorphologist

AbstractThis paper provides the editorial to accompany a Special Issue of Earth Surface Processes and Landforms produced to honour the memory of Professor Ken Gregory, a key figure in late 20th‐ and early 21st‐century geography and geomorphology. It provides an overview of Ken Gregory's career in research, teaching, and university administration, and elaborates on his key research contributions and legacy across geography and geomorphology. Ten interrelated research themes are identified where Ken made particular impacts: (1) river catchment processes and process–form relationships; (2) wood in rivers; (3) anthropogenic impacts on rivers and catchments; (4) approaches to river management that better respect natural processes; (5) public perceptions of rivers; (6) quantitative palaeohydrology; (7) chronology of river floods and deposits; (8) key physical geography/geomorphology concepts and their metrics; (9) the nature of the discipline of physical geography; and (10) concepts in physical geography teaching. These themes provide a framework to introduce the papers in this Special Issue. Through his publications, leadership style, personality, and positive influence on the many people with whom he interacted, Ken Gregory has left a legacy that will continue to inspire present and future generations of geographers and geomorphologists.

Luminescence chronology of Late Quaternary palaeo-lake deposits from the Upper Alaknanda Basin, Uttarakhand, India: Implication to palaeoclimate and depositional settings

• A paleo-lake deposit is reported from Upper Alaknanda Basin in the Badrinath Valley. • OSL dating reveals 1st phase of sedimentation between 21.6 ± 4.7 to 10.5 ± 1.4 ka. • Two phases of paleo-lake formation and outburst observed in the Badrinath Valley. • Higher sedimentation characterise warm and wet periods (ca. 19 to 15 ka; 11 to 10 ka). • Lower sedimentation rate , rhythmite and varve deposits correspond to a colder period (ca. 22 to 19 ka, and around 15 ka). Lakes downstream of the glaciers receive glacial meltwater and sediment supply resulting in formation of thick succession of lacustrine deposits. In this work, we have identified one such palaeo-lake deposit in the Upper Alaknanda Basin, close to Badrinath town. The sediments are of lacustrine origin; however the continuity is broken by intermittent fluvial deposits, which indicate changes in the depositional environment. We used Optically Stimulated Luminescence (OSL) dating to develop a robust chronology of the palaeo-lake deposit. Grain size analyses of sediments were carried out to understand the depositional environment, and morphometric analysis of the valley was conducted to obtained clues about the neotectonic activities in the region. The OSL ages show that the deposition of the lake sediments occurred between 21.6 ± 4.7 ka to 10.5 ± 1.4 ka. Two phases of paleo-lake deposit and subsequent outburst is established from the OSL age, grain size distribution and on the basis of field observations. The high sedimentation rate in the upper part of the deposit indicates an increase in the monsoonal rainfall and glacial retreat post Younger Dryas event. The colder periods are represented by varves and rhythmites, while the warmer periods are represented by thick laminated sand. This study indicates that the glaciers in the Upper Alakanada Basin responded to the fluctuations in the palaeo-climate.