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Winter Wonderland Cave contains perennial ice associated with two types of cryogenic cave carbonate (CCC) formed during the freezing of water. CCCfine is characterized by relatively high δ13C values, whereas CCCcoarse exhibits notably low δ18O values indicating precipitation under (semi)closed-system conditions in a pool of residual water beneath an ice lid. Previous work has concluded that CCCcoarse forms during permafrost thaw, making the presence of this precipitate a valuable indicator of past cryospheric change. Available geochronologic evidence indicates that CCC formation in this cave is a Late Holocene or contemporary process, and field observations suggest that the cave thermal regime recently changed in a manner that permits the ingress of liquid water. This is the first documented occurence of CCCcoarse in the Western Hemisphere and one of only a few locations where these minerals have been found in association with ice. Winter Wonderland Cave is a natural laboratory for studying CCC genesis. [ABSTRACT FROM AUTHOR]

The Buckskin Gulch locality in Utah is a landmark example of compaction localization. The outcrop of this locality involves distinct stratigraphic heterogeneity and was exposed to complex loading history. It features multiple sets of deformation bands with different kinematics and orientation. Similar formations were seen in the Valley of Fire, Nevada, and the Orange quarry, France, among other localities. The formation of such complex structures, their propagation mechanisms, and frequency is affected by numerous local and ambient factors whose impacts are not yet fully understood. The simulation of the above‐mentioned localities is not feasible because of the limited amount of available information. This work, instead, investigates from a geomechanics standpoint how the interplay among material nonlinearity, outcrop stratigraphy, and loading history interconnects with specific spatiotemporal patterns of compaction band propagation. Our study shows that the system stratigraphy can be responsible for the emergence of coexisting compaction bands with different inclination and kinematics. Specifically, we show that stiffness contrasts induce nonlocal stress changes which may favor the initiation of secondary structures with different compaction localization characteristics. Furthermore, systems of inclined compaction bands induced by burial increase display secondary, noncontemporaneous sets of vertical compaction bands under the effects of postburial shortening. Our results indicate that stages of intermediate burial decrease prior to tectonic shortening can promote the formation of such complex systems. Despite the simplifications involved in our analyses, these findings show how geomechanics computations complement field observations and could provide a mechanics‐based validation of site‐specific reconstruction hypothesis. Key Points: Geomechanical modeling provides guidance to interpret complex field structures of localized compactionStiffness contrasts due to stratigraphic heterogeneity cause coexisting modes of compaction bands by inducing nonlocal secondary structuresPostburial tectonic shortening can induce noncontemporaneous, vertical compaction bands secondary to prior shear‐enhanced compaction bands [ABSTRACT FROM AUTHOR]

Slopes undergoing deep-seated gravitational deformation create surface landforms that, if trenched and dated, yield critical data on slope kinematics. The northern slope of Pic d'Encampadana descends steeply 800 m down into the glaciated Valira d'Orient of Andorra and has long been known for its numerous antislope scarps (sackungen), indicative of deep-seated gravitational slope deformation (DSGSD). We excavated three trenches across antislope scarps and their adjacent troughs to date the deformation structures and to infer slope kinematics. Trough deposits have been disrupted by normal and reverse faulting, with the largest fault zone underlying the antislope scarp and dipping into the slope at 40°-80°. Trenches in the troughs expose fining-upward sequences of strata from which we interpret several cycles of: (1) episodic downdropping along graben faults and deepening of the topographic trough, (2) filling the trough with marginal colluvial and axial sag-pond sediments, followed by (3) a hiatus of soil profile development. The average time between deformation events in any one trench in the past 12–15 ka is about 3–3.5 ka. Deformation seems to have begun first in the lower part of the northern slope (1935 m elevation) about 15.3 ka, and had spread to the upper parts of the slope (2320 m) by 11.6 ka. Deformation in the lower slope ceased after 5.5 ka, but continued higher on the slope into the mid-late Holocene. The youngest deformation dated (1.4–1.6 ka) occurred in the highest trench on the slope. This pattern of younger deformation with increasing elevation has been documented at several other sites and has been ascribed to an upslope-migrating extensional stress field which originated at the base of the slope from glacial oversteepening and end-glacial debuttressing. Unlabelled Image • Reconstruction of a deep slope failure movement chronology by trenching • Trenches were in closed depressions (troughs) formed by antislope scarps • Slope deformation episodes represented by faulting/folding of trough deposits • Deformation episodes began immediately post-LGM and recur every 3 to 3.5 kyr • 3D geometry of weak and strong rock units underlying the slope controls the style of deformation [ABSTRACT FROM AUTHOR]

Abstract Kettle holes are a circular-shape product of ice decay, and thus are strongly linked with young glacial landscapes. Once glaciation terminates, these holes transform either into wetland and lakes or occasionally into kettle-hole mires. Since an entire sediment sequence preserve in the kettle-holes, these provide an excellent settings to exploit any sensitive paleoenvironmental changes. Here, the kettle-hole mire located onto the Brda River outwash plain (Tuchola Forest) is explored towards a better understanding of local and global environmental trends in the Late Glacial – present day time frame. To fulfill this, multi-proxy study as geochemical, palynological and macrofossils analyses along with the radiocarbon dating are used. Therefore, this study allows to distinguish five phases of steep environmental gradients in the investigated mire, as follows: (1) paludification after glaciation, when dead-ice melted and long-term permafrost was degraded, (2) lake started to disappear in the Late Glacial, followed by a rich vegetation in the first part of the Holocene, (3) vegetation encroachment onto the lake in the first part of the Holocene, which consequently turned into an peat bog, (4) the late Holocene peat bog with a limited human influence, and finally (5) the peat bog with a major human impact along with acidification as related to sandy underlying sediments, leaching of calcium carbonate, recharge from precipitation and pine monoculture. As additionally apparent from this small ecosystem, both local (character of substrate sediments, morphology of the area, rate of permafrost melting, climate conditions and human activity) and regional (climate changes and human activity) are detectable. Nevertheless, the record of these changes is sometimes unclear. Highlights • Multi-proxy study of biogenic kettle-hole sediment in North Central Poland. • Kettle-hole developed in five phases in the Late Glacial – the Holocene time frame. • Record of vegetational and chemical changes in the kettle-hole sediments • Intensive erosion along with acidification took place. • A greater human impact at the end of the Atlantic [ABSTRACT FROM AUTHOR]

Abstract The study of two caves from the Serra do Ramalho region is here presented, this is one of the most important karstic areas in Brazil. A taxonomic analysis revealed 29 taxa including Xenarthra, Cetartiodactyla and Carnivora, ranging from Late Pleistocene to Early Holocene. Taphonomic studies reveal taphocoenosis consisting mainly of complete elements, without significant transportation, but also of transported elements, composing spatial-mixed, predominantly in situ-preserved assemblages. The predominance of Xenarthrans found within the caves is probably biased by a taphonomic pattern since these animals would have life habits related to cave environments, therefore with higher chances of preservation. There is evidence of accidental death of the scelidotheriines in Lapa dos Peixes cave, where entrapment of the animals during one or more events of river flooding is pointed as a hypothesis. Deposition took place within different periods of dry and humid climate incorporating bones in clastic and chemical deposits. Cycles of sedimentary deposition and reworking (erosion) may have acted in generating complex and overlapping depositional patterns with time averaging. During depositional phase, while the cave environment was occupied rather by Xenarthrans, parts of other animals were transported in the scope of fluvial systems and gravity loads, as well as by accidental falling or scavengers. The sedimentary deposits are currently being eroded by rain runoff in both caves, causing the reallocation of finer sediments to deeper conduits but the fossils keep close to their original location. This process is exposing a large amount of fossils, allowing extensive sampling which would be impossible with active excavations, since it would require an excessively longer time and damages to the caves. Highlights • Fossils naturally exposed by erosion were studied in two caves from Brazil. • 29 taxa, mostly Xenarthrans, were found with life habits related to caves. • Taphocoenosis mainly of complete elements, but also transported elements. • Dry and humid climates formed clastic and chemical deposits with time averaging. • Low energy erosive phase has transported fine sediments while keeping the fossils in place. [ABSTRACT FROM AUTHOR]

Abstract The ages and sizes of landslides occurring in seismically active areas can be used to reconstruct the seismic history of the area and estimate the maximum moment magnitudes of past earthquakes. Here, we present a data set of 121 landslides discovered in northern Finland that were analyzed for their morphometric characteristics. We show that 89 debris slide type landslides in the data set are clustered close to known postglacial faults (PGFs) and thus provide information on the characteristics of postglacial paleoseismic events. By using empirical correlations between the landslide volume–area data and earthquake moment magnitude, we estimate maximum moment magnitudes M w ≈ 6.9–7.7 for postglacial earthquakes in the Suasselkä, Isovaara–Riikonkumpu, Venejärvi, and Vaalajärvi areas, where earlier estimates based on fault length and displacement have yielded magnitudes varying between M w ≈ 6.5 and 7.5. We also show that the landslides in northern Finland are located within a radius of 35 km from the closest known PGF and that sizes of the landslides decrease as a function of distance from PGFs, hence providing strong empirical evidence for their seismic origin. As far as we are aware, this is the first use of landside data in quantifying postglacial seismicity within the Fennoscandian Shield area. Highlights • 121 landslides from Finland were analyzed for morphology and paleoearthquake origin. • Debris slide type of landslides fulfills the criteria of being seismically-induced. • Landslide volume–area data indicate M w ≈ 6.9–7.7 postglacial earthquakes in Finland. • These estimates agree well with M w ≈ 6.5–7.5 estimates that are based on PGF ruptures. [ABSTRACT FROM AUTHOR]

Abstract The Selandian-Thanetian (S/Th) succession is extensively represented and well exposed along the eastern escarpments of the Kharga Oasis, Western Desert, encompasses the upper part of the Dakhla Formation, Tarawan Formation and the lower part of the Esna Formation. This study based on the qualitative and quantitative investigation of the planktonic and benthic foraminiferal assemblages aims to assess and specify the S/Th transition in terms of the biostratigraphic, paleoecologic and sequence stratigraphic analyses. The studied interval is subdivided into three 3rd order depositional sequences (Seq. 1, Seq. 2 and Seq. 3) separated by two sequence boundaries at the Dakhla/Tarawan (SB 1) and the Tarawan/Esna (SB 2) contacts, respectively. The S/Th boundary is placed at the Maximum Flooding Surface (MFS) of the second depositional sequence (Seq. 2) within the Tarawan Formation and lies at about 6 m above the base of a distinct thin layer related to the Mid-Paleocene Biotic Event (MPBE). The S/Th MFS is characterized by a relatively highest positive peak in the P/B ratio (90%) and the common occurrence of the bathyal benthic taxa. The reported MFS displays great correspondence with the eustatic sea-level related to the timing and extent that can be treated as a secondary criterion relevant for delineating and correlating the Selandian-Thanetian transition everywhere. Highlights • This work evaluates the Selandian-Thanetian transition. • The foraminiferal analyses are used to evaluate the paleoenvironmental conditions. • The studied interval is subdivided into three 3rd order depositional sequences. • The Selandian/Thanetian boundary is placed at the MFS of the second sequence. [ABSTRACT FROM AUTHOR]

Mineral magnetic studies of Holocene lake sediments recovered from Zaca Lake, in coastal southern California have yielded a 3000-year high-resolution record of terrestrial hydrologic variability and paleolimnology. Samples for magnetic analysis were obtained from an 8.73 m core recovered from the central region of Zaca Lake. Ages, constrained using a combined paleomagnetic and radiocarbon chronostratigraphy, yield sedimentation rates of 2–10 mm/yr with an average rate of 3 mm/yr over the 3000-year interval. Parameters reflecting decadal-scale variability in magnetic concentration (susceptibility, ARM, SIRM) and grain size (ARM/Chi) were measured every 2 cm. Additional rock magnetic tests on whole rock samples and magnetic separates indicate that magnetite and an iron sulfide are the chief magnetic carriers. Detailed analysis of the rock magnetic record reveals four major temporal intervals: 0–135 cm (~AD 2009–1757) the period of European settlement; 135–270 cm (~AD 1757–1275) the period of Native American, Chumash occupation of the watershed encompassing the bulk of the wet interval known as the little ice age (LIA); 270–600 cm (AD 1275–100) encompassing the drier Medieval Climate Anomaly (MCA); and 600–875 cm (2000–3000 ybp) an era dominated by a long interval of low magnetic mineral intensity and concentration that has been interpreted as a time of epic drought. Beginning with the cessation of drought conditions at Zaca Lake around ~2000 ybp, the magnetic proxy record of rock magnetic cyclicity and hydrologic variability shows a pronounced decadal to centennial-scale periodicity. We interpret these periodicities as oscillations between summer-dominated sedimentary sequences, characterized by whiting events with their resulting carbonate deposits, and winter dominated sedimentary sequences, typified by sulfide-rich clastics, reflecting lacustrine overturn and enhanced advection of detrital flux during winter storm events. The long-term variation of summer versus winter-dominated weather patterns reflects the climate variability of central California coast-ranges. [ABSTRACT FROM AUTHOR]

Uncertainty about controls on long-term carbon (C) and nitrogen (N) balance, turnover, and isotopic composition currently limits our ability to predict ecosystem response to disturbance and landscape change. We used a two-century, postglacial chronosequence in Glacier Bay, Alaska, to explore the influence of C and N dynamics on soil and leaf stable isotopes. C dynamics were closely linked to soil hydrology, with increasing soil water retention during ecosystem development resulting in a linear decrease in foliar and soil δ13C, independent of shifts in vegetation cover and despite constant precipitation across sites. N dynamics responded to interactions among soil development, vegetation type, microbial activity, and topography. Contrary to the predictions of nutrient retention theory, potential nitrification and denitrification were high, relative to inorganic N stocks, from the beginning of the chronosequence, and gaseous and hydrological N losses were highest at mid-successional sites, 140-165 years since deglaciation. Though leaching of dissolved N is considered the predominant pathway of N loss at high latitudes, we found that gaseous N loss was more tightly correlated with δ15N enrichment. These results suggest that δ13C in leaves and soil can depend as much on soil development and associated water availability as on climate and that N availability and export depend on interactions between physical and biological state factors. [ABSTRACT FROM AUTHOR]

Within the Egyptian Western Desert, the Kharga Oasis was a particularly favourable and highly frequented area during the Holocene thanks to a permanent ground water supply. The high concentration and accessibility of archaeological sites here allows the cultural and economic changes to be documented at a local scale, when northeastern Africa was experiencing strong climatic variations and the transition to a food production economy. An expansive program led by the Institut français d'archéologie orientale (IFAO) which included systematic survey, sampling collections, tests and stratigraphic excavations has dramatically increased the amount of data available concerning the prehistory of the Kharga Oasis. Typo-technological analyses focusing on the lithic industries, and other aspects of material culture, plus a series of 14C dates have led to the definition of four main successive cultural phases: Kharga A, B, C and D. This paper describes this proposal of a new archaeological sequence for human occupation in the Kharga Oasis and discusses its integration in the wider frame of Egypt and the Eastern Sahara. [ABSTRACT FROM AUTHOR]

Abstract Marine faunal remains from Grotta d'Oriente (Favignana Island, NW Sicily) offer invaluable snapshots of human-coastal environment interaction in the central Mediterranean from the Late Pleistocene to the Middle Holocene. The long-term shellfish and fish records reflect human exploitation of coastal environments undergoing considerable reorganizations during the postglacial sea level rise and the progressive isolation of Favignana from mainland Sicily. We detected an intensification of marine resource exploitation between ∼9.6 ka and ∼7.8 ka BP, which corresponds with the isolation of Favignana Island and, later on, with the introduction of early agro-pastoral economy in this region. We suggest that a higher investment in marine resource exploitation by late foragers and early farmers in NW Sicily was also supported by an increase in marine productivity in the south Tyrrhenian Sea in the Middle Holocene. [ABSTRACT FROM AUTHOR]

Abstract This paper discriminates the source of sediment supply (provenance), degree of chemical weathering, and redox conditions of Holocene sediments cored from the Ankobra and Pra estuaries of Ghana in the Gulf of Guinea using their geochemical characteristics. Considerable stratigraphical variations were observed in major element compositions in the sediments from both the Ankobra (Al 2 O 3 : 5.3–14.2%, SiO 2 : 75.9–88.2%, CaO: 0.3–1.2%, K 2 O: 0.5–1.2%) and the Pra (Al 2 O 3 : 7.8–16.9%, SiO 2 : 72.8–86.5%, CaO: 0.3–0.4%, K 2 O: 0.7–1.2%) estuaries. Elemental compositions were similar in both estuaries depicting similarities in their source rock characteristics. Some of the major and trace elements correlated significantly (r2 > 0.8) with Al 2 O 3 in the Pra estuary confirming their possible hydraulic fractionation. Geochemical classification showed the sediments from both estuaries were predominantly composed of sub-arkoses with only a few litharenites. The chemical index of alteration (CIA*), Chemical index of weathering (CIW*), plagioclase index of alteration (PIA*), the Index of compositional variability (ICV), the SiO 2 /Al 2 O 3 ratios and SiO 2 vs. (Al 2 O 3 +K 2 O + NaO), suggest high degrees of chemical weathering coinciding with warm climatic conditions in the source regions as well as sub-matured to mature estuarine sediments deposited under semi-arid to semi-humid conditions. The sediment geochemistry and discrimination diagrams denote similar continental signature derivatives of the sediments from both estuaries. Both sediments are likely derived from intermediate to felsic granitoid source rocks as well as from a quartzose sedimentary provenance formed in a passive continental margin. The Ni/Co and V/Cr ratios depict sediment deposition under oxic conditions through time in both estuaries. [ABSTRACT FROM AUTHOR]

A new species of stick insect, Diapheromera arena n.sp., from western Texas and New Mexico is the first new species of Diapheromera described from the United States in several decades. It lacks armature on the head of both sexes and has a unique apomorphy of a distinctly swollen third antennal segment that easily differentiates it from other species in that genus. Despite being broadly sympatric with Diapheromera velii Walsh, the occurrence of this new species only in areas of windblown sand and sand dunes appears to function as habitat separation between these two related stick insects at the local level. Despite the new species' relatively large geographic range, it is a rare taxon and much less common than Diapheromera velii in the same region. This new species is part of the specialized sandy environment ecosystem including endemic plants, other insects, and vertebrates in western Texas and New Mexico [ABSTRACT FROM AUTHOR]

We have studied the rock magnetic characteristics of 31 multicores and 7 gravity cores from deep-sea sediments of the distal Amazon Fan and Demerara Abyssal Plain. This study has permitted us to delineate the space/time pattern of Holocene physical sedimentation along the northeastern margin of South America associated with the Amazon River sediment plume. The rock magnetic variability is correlatable over the entire study region. This degree of correlation has permitted us to develop a composite picture of Holocene rock magnetic (and overall physical clastic) sedimentation. 26 radiocarbon dates have been combined with the rock magnetic correlations to provide a composite Holocene chronostratigraphy for that variability. We have built isopach maps of overall sedimentation for three windows in the Holocene (3000, 4500, and 7000 calendar years BP). The overall sedimentation in the center of our region is ~5 cm/kyr. But, sedimentation rates are faster closer to the coastline and associated with the distal clastic flux from the Amazon Plume. There is a secondary high in sediment accumulation under the North Brazil Current retroflection. Our maps suggest that the retroflection has been active at the millennial scale for at least the last 7000 years. We estimate that the mid-Holocene (~4.5–9000 calendar years BP) pattern of sedimentation was distinctly different from that of the last few thousand years. The clastic sediments were ~25% reduced in concentration (with the biogenic sediments similarly increased by ~25%), they were finer–grained, and significantly less rich in ferric iron phases (hematite/goethite). We think these three covarying clastic parameters are due to an interval of reduced clastic flux from the Amazon River Plume with a reduced proportion of Amazon Basin sediments (as opposed to Andes-derived sediments). We hypothesize this was due to significantly drier Amazon Basin environmental conditions during that time interval. [ABSTRACT FROM AUTHOR]

Abstract Soft-sediment deformation structures are preserved in clastic-biogenic varves of the Lake Nurmijärvi sequence from central-southern Finland. Deformation structures include centimeter-scale folding and faulting structures and larger convolute bedding, which are separated from the overlying undisturbed varved section by a turbidite dated at 7400 cal BP. The soft-sediment deformation provides evidence for postglacial seismic activity ca. 3500 years after the deglaciation of the study area. By screening the sizes of potential source faults for the event, the maximum earthquake moment magnitudes associated with the deformation structures were constrained to M W ≈ 5.1–6.9 with realistic 40% rupture scenarios, or up to M W ≈ 5.1–7.7 if more conservative scenarios are considered. The results of the study thus indicate a relatively high-magnitude postglacial seismic event in southern Finland, which adds to the evidence that the postglacial seismic activity was not just restricted to northern Fennoscandia, but was a more widespread phenomenon. The age of the Lake Nurmijärvi seismic event further demonstrates that high-magnitude seismic activity was not restricted to a relatively short period after deglaciation, but the period of high-magnitude postglacial seismic activity was much longer than previously thought. By assessing the orientations of faults that are presently active and using available focal mechanism data, our results suggest that strike-slip faulting may be a more important mechanism for the generation of both present-day and postglacial earthquakes in southern Finland than reverse faulting, which should further be accounted for in the assessment of long-term seismic hazards. Graphical abstract Unlabelled Image Highlights • Soft-sediment deformation structures (SSDS) in the Lake Nurmijärvi clastic-biogenic varved section are described. • Deformation structures we interpreted as seismically-induced and dated to 7400 cal BP • An earthquake of Mw ≈ 5.1–6.9 was calculated for the Nurmijärvi paleoseismic event. [ABSTRACT FROM AUTHOR]

There is evidence for early Pleistocene Homo in northern Europe, a novel hominin habitat. Adaptations enabling this colonisation are intriguing given suggestions that Homo exhibits physiological and behavioural malleability associated with a ‘colonising niche’. Differences in body size/shape between conspecifics from different climates are well-known in mammals, could relatively flexible size/shape have been important to Homo adapting to cold habitats? If so, at what point did this evolutionary stragegy arise? To address these questions a base-line for adaptation to climate must be established by comparison with outgroups. We compare skeletons of Japanese macaques from four latitudes and find inter-group differences in postcranial and cranial size and shape. Very small body mass and cranial size in the Southern-most (island) population are most likely affected by insularity as well as ecogeographic scaling. Limb lengths and body breadths show group differences that accord with the expectations of thermoregulation across the whole range of latitudes. Postcranial size appears to vary more than shape, yet there is also evidence that limb segments follow Allen's rule in the forelimb at least, suggesting differing climatic signals in different regions of the skeleton. In contrast to other intraspecific studies of catarrhine ecogeography, the results presented here demonstrate non-allometric latitudinal patterns in craniofacial shape in Japanese macaques, which align closely with what is seen in cold-adapted humans. These insights begin to provide a comparison for hominin adaptation to similar habitat diversity and the role of biological adaptation in shaping the evolution and dispersal of Homo species. [ABSTRACT FROM AUTHOR]

Trench excavations across the El Molino fault in the southeastern Pampean Ranges of central-western Argentina have revealed a deformation zone composed of opposite-verging thrusts that deform a succession of Holocene sediments. The west-verging thrusts place Precambrian basement over Holocene proximal scarp-derived deposits, whereas the east-verging thrusts form an east-directed fault-propagation fold that deforms colluvium, fluvial and aeolian deposits. Ages for exposed fault-related deposits range from 7.1 ± 0.4 to ~0.3 ka. Evidence of surface deformation suggests multiple rupture events with related scarp-derived deposits and a minimum of three surface ruptures younger than 7.1 ± 0.4 ka, the last rupture event being younger than 1 ka. Shortening rates of ~0.7 ± 0.2 mm/a are near one order of magnitude higher than those estimated for the faults bounding neighboring crustal blocks and are considered high for this intraplate setting. These ground-rupturing crustal earthquakes are estimated to be of magnitude M w  ≥ 7.0, a significant discrepancy with the magnitudes M w  < 6.5 recorded in the seismic catalog of this region at present with low to moderate seismicity. Results highlight the relevance of identifying primary surface ruptures as well as the seismogenic potential of thrust faults in seemingly stable continental interiors. [ABSTRACT FROM AUTHOR]

After retreat of the Cordilleran Ice Sheet (CIS) and subsequent glacio‐isostatic adjustment of the central coast of British Columbia (BC), Canada, a complex coastline emerged as relative sea level rapidly reached equilibrium and maintained stability over the end of the Late Pleistocene and Holocene. This study provides a late Quaternary reconstruction of the landscape evolution of a geographically distinct location on the central BC coast, northwest Calvert Island, which experienced a re‐advance of the CIS near the end of the Late Pleistocene and minimal subsequent relative sea‐level change. Geomorphological observations from LiDAR imagery, sedimentological and palaeoecological evidence from exposures, cores and shovel pits, and a robust luminescence and 14C‐based chronology spanning the last 15 000 years are used to reconstruct the landscape of northwest Calvert Island following CIS retreat. A single‐aliquot regenerative dose protocol that was developed specifically for luminescence dating of the sediments on Calvert Island was utilized in this study. Localized proglacial sedimentation was linked to the glacial re‐advance experienced at the end of the Late Pleistocene. Extensive coastal reconfiguration (e.g. rapid shoreline progradation of >1 m a−1) occurred in the absence of extensive RSL change, which was the main driver of coastal change elsewhere along the BC coast. Changes in climate, small magnitude changes in RSL, and fire all probably played a role in isolated aeolian landform development and stabilization in the study area. An important contribution of this study is the documentation of the multi‐disciplinary approach for reconstructing palaeogeography, using multiple geochronological methods, micro‐ and macro‐sedimentology, the palaeoecology inferred from both macro and microfossils (e.g. diatoms and foraminifers), stratigraphy, field mapping and remote sensing. In addition, these findings inform our understanding of the drivers of coastal sedimentary processes, particularly in the temperate coastal rainforest region of BC, and the role that fire may play in those processes. Coastal palaeogeography studies in the region will become increasingly important as discoveries of Late Pleistocene human habitation along the coastal migration route continue to be documented. [ABSTRACT FROM AUTHOR]

Analysis of 56 outcrop exposures in cut banks along the Nottawasaga River in southern Simcoe County, Ontario, Canada, has led to the identification of eight stratigraphic units (SU1-SU8) that represent a record of changing environmental conditions during deglaciation and exhibit strong controls on shallow groundwater flow in the region. The stratigraphic succession is floored by the Late Wisconsin Newmarket Till (SU1), which is locally overlain by ice-proximal debris flow deposits (SU2). These glacial sediments are overlain by glaciolacustrine silt rhythmites (SU3) that pass upwards into deltaic sand (SU4) and channelized fluviodeltaic sand and gravel (SU5). Lying above the fluvial deposits are widespread interbedded glaciolacustrine sands and silt (SU6), which coarsen up-section toward the ground surface. The succession is locally capped by fluviodeltaic (SU7) and younger fluvial (SU8) deposits. These SUs record sedimentary environments that existed during deglaciation of the region and provide insight into the evolution of glacial lakes Schomberg and Algonquin and the Nipissing phase of the upper Great Lakes. The environmental changes described from sediments along the Nottawasaga River provide insights into basin-scale events that occurred throughout the upper Great Lakes during deglaciation. Qualitative observations of groundwater discharge from sediments at outcrop faces are used to characterize the hydraulic function of the stratigraphic units as well as possible preferential groundwater flow pathways in the shallow subsurface. [ABSTRACT FROM AUTHOR]

Several stages are recognizable in landscape evolution along the Eastern Primorye coast, Kit Bay and its surrounding mountains in terms of climatic changes and related sea level fluctuations during the middle–late Holocene. The last 3.8–3.5 cal ka years were marked by a notable effect of the pyrogenic factor. The sea level rise at the maximum phase of the Holocene transgression led to the formation of lagoons at stream mouths, which underwent a complicated development. At that time, the coast’s principal topographic elements came into being, and the modern landscape’s pattern was laid on the coastal lowlands. The authors trace the changes in the vegetation in the process of short-term warmings and coolings. Korean pine appeared in the forests surrounding Kit Bay much earlier than in other regions of the Eastern Primorye. During the considered period, warmer phases were marked by increasing importance of broadleaf species, while at the cooler phases, a proportion of the Korean pine grew in the low mountains. In the last 2.3 cal ka, at greater elevations in the middle mountains, dark coniferous forests became more widespread, particularly spruce. At the same time, larch groves existed around the coastal sphagnum bog, probably due to seasonally frozen ground persisting for the greater part of a year. Extreme events with a considerable effect on the coastal landscape evolution include floods, whose frequency has been growing for the last 1.75 cal ka. Strong tsunamis are another factor influencing coastal evolution. Finally, changes in landscapes have been recorded related to human activities in the last few decades. [ABSTRACT FROM AUTHOR]

Geochemistry, sediment provenance, and the Holocene paleoenvironmental evolution of the Southern Po River coastal plain (Italy) were examined based on the geochemical analysis of 279 sediment samples from 35 cores. The Holocene succession is subdivided into four major facies associations: back‐barrier, transgressive barrier, shallow‐marine, and beach‐ridge deposits. Bulk chemical composition shows remarkable differences between facies associations, and the poly‐modal behavior in the related frequency curves suggests distinct sources of sediment. Using MgO and Ni as geochemical tracers, changes in sediment provenance were assessed with the aim to reconstruct the Holocene paleoenvironmental evolution of the area. The Po River and the Apenninic rivers represented the main sources of sediment during the early stages of transgression and highstand sea‐level conditions, whereas transgressive barrier and early shallow‐marine facies associations exhibit a clear North Adriatic river (eastern Alpine) provenance. The Holocene paleoenvironmental evolution of the study area, between about 10 ky and the present, indicates the presence of a bypass zone in front of the Po River mouth between 9 and 6 ky BP. At that time, sediment supplied by the North Adriatic rivers was transported southward by the longshore drift, bypassed the weak Po River influx and accumulated close to the Apennines. Comparison between Holocene facies associations and current back‐barrier and shallow‐marine sediments confirms that the present‐day basin circulation is similar to the one that acted during the last episode of sea‐level rise. [ABSTRACT FROM AUTHOR]

Ongoing glacial isostatic adjustment (GIA) due to surface loading (ice and water) variations during the last glacial cycle has been contributing to sea-level changes globally throughout the Holocene, especially in regions like Canada that were heavily glaciated during the Last Glacial Maximum (LGM). The spatial and temporal distribution of GIA, as manifested in relative sea-level (RSL) change, are sensitive to the ice history and the rheological structure of the solid Earth, both of which are uncertain. It has been shown that RSL curves near the center of previously glaciated regions with no ongoing surface loading follow an exponential-like form, with the postglacial decay times associated with that form having a weak sensitivity to the details of the ice loading history. Postglacial decay time estimates thus provide a powerful datum for constraining the Earth's viscous structure and improving GIA predictions. We explore spatial patterns of postglacial decay time predictions in Hudson Bay by decomposing numerically modeled RSL changes into contributions from water and ice loading effects, and computing their relative impact on the decay times. We demonstrate that ice loading can contribute a strong geographic trend on the decay time estimates if the time window used to compute decay times includes periods that are temporally close to (i.e. contemporaneous with, or soon after) periods of active loading. This variability can be avoided by choosing a suitable starting point for the decay time window. However, more surprisingly, we show that across any adopted time window, water loading effects associated with inundation into, and postglacial flux out of, Hudson Bay and James Bay will impart significant geographic variability onto decay time estimates. We emphasize this issue by considering both maps of predicted decay times across the region and site-specific estimates, and we conclude that variability in observed decay times (whether based on existing or future data sets) may reflect this water loading signal. [ABSTRACT FROM AUTHOR]

This paper reexamines the late Pleistocene to early Holocene transgressive succession (ca. 19.0-8.0 cal. k.y. B.P.) beneath the modern Changjiang delta plain, one of the world's great rivers, by means of a detailed process-oriented investigation of the sedimentary facies and stratigraphic architecture in two newly drilled cores (ZK01 and ZK02), supplemented by correlation with previous work and comparison with the modern deltaic deposits. Results suggest that the study interval, which has previously been considered to have accumulated in an estuary, instead represents a back-stepping delta. The target succession shows a general fining- and muddier-seaward trend for both the channel-bottom and adjacent tidal- or point-bar sediments, from coarse sand and gravels of the purely fluvial channel, through tide-influenced fluvial-channel deposits dominated by medium to coarse sand, to fine-grained sandy or muddy deposits of the (terminal) distributary channels, and finally to prodeltaic mud; the sand-dominated deposits that characterize transgressive estuary mouths are not present. The prodeltaic and delta-front deposits of the paleo- and modern Changjiang deltas display strong similarities, including the pervasive interbedding of tideand wave-generated fluid-mud deposits and muddy tidal-bar deposits, which are punctuated by terminal-distributary-channel facies that are not expected in an estuary. In more detail, three superimposed successions are recognized, each of which displays an upward-shallowing trend indicating a progradational nature, which is also indicated by the presence of seaward-dipping seismic reflectors in the correlative seaward part of this stratigraphic interval. The three successions show an overall retrogressive, fining-upward trend as a result of stepwise transgression like that seen in the Mississippi and Ganges-Brahmaputra River deltas. This architecture indicates that the large sediment supply of the Changjiang was able to keep pace with or exceed the rate of relative sea-level rise at certain times and locations during the later part of the postglacial transgression. We also propose that the maximum flooding surface occurred at ca. 9.0 cal. k.y. B.P., which is earlier than previously thought; this is also a reflection of the high rate of sediment input of the Changjiang, which causes a turnaround from net transgression to net progradation to occur when the rate of sea-level rise is higher. This study shows that we should not just simply interpret any transgressive succession in an incised valley as estuarine. This study provides significant new insights into the interpretation and sequence-stratigraphic reconstruction of ancient deltaic deposits, and it advances our understanding of the nature of tide-dominated delta successions. [ABSTRACT FROM AUTHOR]

Tephra (volcanic ash) layers have the potential to synchronise disparate palaeoenvironmental archives on regional to hemispheric scales. Highly productive arc regions, like those in East Asia, offer a considerable number of widespread isochrons, but before records can be confidently correlated using these layers, a refined and integrated framework of these eruptive events is required. Here we present the first high-resolution Holocene cryptotephra study in East Asia, using the Lake Suigetsu sedimentary archive in central Japan. The Holocene tephrostratigraphy has been extended from four to twenty ash layers using cryptotephra extraction techniques, which integrates the deposits from explosive eruptions from North Korea/China, South Korea and along the Japanese arc. This Lake Suigetsu tephrostratigraphy is now the most comprehensive record of East Asian volcanism, and the linchpin site for correlating sequences across this region. Major element glass geochemical compositions are presented for the tephra layers in the sequence, which have been compared to proximal datasets to correlate them to their volcanic source and specific eruptions. This study has significantly extended the ash dispersal of many key Holocene marker layers, and has identified the first distal occurrence of isochrons from Ulleungdo and Changbaishan volcanoes. Utilising the high-precision Lake Suigetsu chronology, we are able to provide constrained eruption ages for the tephra layers, which can be transferred into other site-specific age models containing these markers. This new framework indicates that several isochrons stratigraphically bracket abrupt climate intervals in Japan, and could be used to precisely assess the regional and hemispheric synchronicity of these events. [ABSTRACT FROM AUTHOR]

The Liaohe Delta in Northeast China is one of the ecologically important estuarine deltas in China. It has been formed via the accumulation of sediment discharged by four rivers in the Liaohe Plain that enter Liaodong Bay. Twenty-seven 30–40 m long cores recovered from the Liaohe Plain and Liaodong Bay were analyzed for sedimentary characteristics, grain size, foraminifera species, and ages determined by accelerator mass spectrometry (AMS) 14 C to document the stratigraphical sequence and the spatio-temporal evolution of the Liaohe Delta. Our results revealed that the sedimentary environments have evolved from fluvial, tidal flat/estuarine, to neritic and finally to a deltaic environment since the Late Pleistocene. The Holocene transgression arrived at the present coastline at ∼8500 cal a BP and flooded the maximum area of land at ∼7000 cal a BP. A deltaic environment prevailed in this area after 7000 cal a BP. Bounded by the modern Liaohe River mouth, the present deltaic sedimentary system can be divided into the eastern and western components. The rate of seaward progradation of the eastern paleocoastline was estimated to be ∼8.6 m/a since 7000 cal a BP; the eastern cores in the present coastline began receiving the deltaic sediments at ∼5000 cal a BP. The rate of seaward progradation of the western paleocoastline was estimated to be only ∼2.8 m/a since 7000 cal a BP. The coastline on the western side began accumulating deltaic sediments about 2000 years later than the eastern coastline. Depocenter shifting was hypothesized to be the reason for the spatial differences in the sedimentary processes. However, the change of sediment fluxes of the western rivers due to climate changes and ancient human impacts might be the reason for the differences of the temporal evolution of the eastern and western sedimentary systems in the Liaohe Delta. [ABSTRACT FROM AUTHOR]

Core 2011804-0010 from easternmost Lancaster Sound provides important insights into deglacial timing and style at the marine margin of the NE Laurentide Ice Sheet ( LIS). Spanning 13.2-11.0 cal. ka BP and investigated for ice-rafted debris ( IRD), foraminifera, biogenic silica and total organic carbon, the stratigraphy comprises a lithofacies progression from proximal grounding line and sub-ice shelf environments to open glaciomarine deposition; a sequence similar to deposits from Antarctic ice shelves. These results are the first marine evidence of a former ice shelf in the eastern Northwest Passage and are consistent with a preceding phase of ice streaming in eastern Lancaster Sound. Initial glacial float-off and retreat occurred >13.2 cal. ka BP, followed by formation of an extensive deglacial ice shelf during the Younger Dryas, which acted to stabilize the retreating margin of the NE LIS until 12.5 cal. ka BP. IRD analyses of sub-ice shelf facies indicate initial high input from source areas on northern Baffin Island delivered to Lancaster Sound by a tributary ice stream in Admiralty Inlet. After ice shelf break-up, Bylot Island became the dominant source area. Foraminifera are dominated by characteristic ice-proximal glaciomarine benthics ( Cassidulina reniforme, Elphidium excavatum f. clavata), complemented by advected Atlantic water ( Cassidulina neoteretis, Neogloboquadrina pachyderma) and enhanced current indicators ( Lobatula lobatula). The biostratigraphy further supports the ice shelf model, with advection of sparse faunas beneath the ice shelf, followed by increased productivity under open water glaciomarine conditions. The absence of Holocene sediments in the core suggests that the uppermost deposits were removed, most likely due to mass transport resulting from the site's proximity to modern tidewater glacier margins. Collectively, this study presents important new constraints on the deglacial behaviour of the NE Laurentide Ice Sheet, with implications for past ice sheet stability, ice-rafted sediment delivery, and ice−ocean interactions in this complex archipelago setting. [ABSTRACT FROM AUTHOR]

With the purpose of tracing the variations of the organic matter sources of sediments, a sample column (25.96 m in size) from the Hemudu Area of Hangzhou Bay was put through AMSC dating and biogeochemical analysis. TOC and TN presented similar variation trends, suggesting the same and stable sources of organic matter; the bad correlation between the grain size and TOC content indicated that the organic matter occurrence was neither controlled by the grain size nor the surface absorption of the fine particles, but it may has something to do with the complicated sedimentary hydrodynamic force, the input of organic matter and microbial action. Judging on the basis of C/N ratio and δC, the organic carbon in sediments was a mixture of terrigenous and marine organic carbon, testifying to the land-sea interaction characteristic of the study area. The indexes experienced abrupt changes at about 6.5 ka BP, when the lighter terrigenous organic carbon made an increased proportion to the heavier marine organic carbon. The phenomenon reflected the enclosure of the lagoon and the reduced exchange interactions with the seawater of open seas. [ABSTRACT FROM AUTHOR]

A multi-scale analysis of sedimentary carbonate facies and post-sedimentary diagenetic features of the Calcare di Base Formation, the precursor to evaporites in Upper Messinian successions of Northern Calabria and Central Sicily, has revealed their microbial bio-mediated origin. Massive to laminated microbial boundstones represent the most common sedimentary facies forming flat to low relief cm to m scale stromatolitic and thrombolitic bodies. The fabric of the micrite varies from peloidal to aphanitic, and almost always preserves filamentous bacteria which characterized the original microbial mat. The mat was dominated by sulphur-oxidizing bacteria belonging to the Thiotrichaceae, but there is evidence for a more complex community with sulphate- and/or nitrate-reducing bacteria, all being responsible for the mediation of the carbonate precipitation. Microbial boundstones are rich in pseudomorphs of Ca-sulphate and halite, which formed during the deposition of the microbial carbonate. Layers of primary gypsum are interbedded locally with carbonates suggesting the presence of restricted marine conditions. The stable O and C isotopic composition of the carbonates, that vary from dolomite to aragonite and calcite, suggests a complex interplay between arid to humid climatic changes, expressed cyclic interbedding of the carbonate with marl-marlstone. Later diagenetic events mainly consist of phreatic meteoric recrystallization and cementation. Although considered as diachronous, the microbial carbonates can be mapped out over a distance of more than 500 km across southern Italy; this indicates near-constant environmental conditions upon the central Mediterranean shelf at the beginning of the salinity crisis. Deposition of the extensive subaqueous microbial deposit that largely comprises the Calcare di Base is envisaged to have taken place across a shallow to moderate depth platform with local slopes into deeper water areas, where some resedimentation occurred. [ABSTRACT FROM AUTHOR]

Detailed field mapping of glacial and paraglacial landforms and optical dating from these landforms are used to reconstruct the early Holocene glaciation in the semi-arid region of Miyar basin, Lahaul Himalaya. The study identifies three stages of glaciation, of decreasing magnitude and termed, from oldest to youngest, the Miyar stage (MR-I), Khanjar stage (KH-II), and Menthosa advance (M-III). The oldest glacial stage (MR-I) has been established on the basis of detailed geomorphological evidence such as U-shaped valley morphology, trimlines, and truncated spurs. It is speculated to be older than the global Last Glacial Maximum (gLGM) based on the magnitude of DELA (Equilibrium-Line Altitude, 606m). No evidence of glacier expansion recorded from the basin correlates with the period of the gLGM. The second stage (KH-II) is well represented by extensive depositional features such as lateral and terminal moraines, drumlins, and lacustrine fills that have been constrained within 10 ± 1 to 6.6 ± 1.0 ka (Optically stimulated luminescence--OSL--ages), dating it to the early Holocene advance following the Younger Dryas cooling event. Exceptionally young glacial records of expansion are limited within a few hundred meters of the present termini of tributary glaciers and correlates with the 18th-century cooling event. Records of this glacial advance, termed the Menthosa advance, are clearly noticed in some tributary valleys. [ABSTRACT FROM AUTHOR]

Water well logs and vibracores recovered from the lower Manawatu valley record the facies architecture, morphostratigraphy, and sedimentary evolution of this drowned river incised-valley estuary over the past c. 30,000 years. The Manawatu incised-valley estuary was rapidly infilled during the Holocene, and as a result preserves a complete record of Holocene estuary evolution. The base of the Holocene fill is marked by fluvial gravels deposited by the Manawatu River during the lowstand of the Last Glacial Maximum. The gravels are overlain by back-stepping transgressive fluvial silts and clays. The transgressive fluvial unit is present only in the lower reaches of the valley due to accelerated sea-level rise during the latter stages of the marine transgression. Large volumes of transgressive marine sediment were delivered to the mouth of the valley by rising sea-levels during the early Holocene, forming a large subaqueous tidal delta. This delta accreted and subsequently evolved to form a subaerial barrier in the mid-Holocene, as sea-levels stabilised during the sea-level highstand. The central basin of the estuary was rapidly infilled by marine and fluvial sediment, and consequently lacks the mud facies characteristic of less-rapidly-evolved estuaries. The transition from the sandy central basin estuarine environment to the overlying floodplain environment was extremely rapid. In some locations in the valley the transitional fluvial bay-head delta is missing completely, while in most locations it is present only as a very thin deposit, indicative of this rapid environmental transition. Infilling of the estuarine central basin was extremely rapid, taking only 2000–2700 years. The unique features of the Manawatu estuary's evolutionary history are interpreted to primarily reflect the rapid infilling of the palaeo-estuary driven by the high rates of sediment supplied to the valley from both marine and fluvial sources. [ABSTRACT FROM AUTHOR]

This paper presents the geological and morphological evolution of the prograded Cassino barrier during the middle and late Holocene. A special focus is given on the presentation and discussion of records of environmental changes that occurred during barrier progradation. The results demonstrated that variable rates of progradation were produced by environmental changes that affected the coastal sediment budget, such as changes in the wave climate. The total progradation of 18 km recorded for the Cassino barrier is probably the highest extension of progradation registered for a ridge plain associated with a coastal barrier. Sea-level changes during barrier progradation were accessed by the high difference between the degree of compaction of the foredune and backshore/foreshore deposits detected by the drilling system applied in this study and were confirmed by the limit of those deposits, which were also revealed by GPR records. During most of the time of barrier progradation, an overall sea-level fall of approximately 2 ± 1 m occurred. Six sets of relict foredune ridges were identified, and the limits between them were well marked by ridge truncations and the formation of transgressive dune sheets (TDS). Optically stimulated luminescence ages show that the TDS were formed under the driest climate conditions, with age periods very close to 3.8, 3.5, 1.9, 1.5, 0.22 and 0.09 ka ago, interspersed with ages of known wetter conditions in southern Brazil. The modern phases of TDS formation, with ages varying from 0.25 to 0.22 ka ago, were coincident with the time period of the younger pulse of the Little Ice Age (LIA), which was characterized by arid and cold conditions in southern South America. A comparison with prograded barriers located 350 to 600 km to the north suggests the existence of teleconnections, with phases of TDS and parabolic dunes that formed with a time interval of approximately 405 to 583 years. [ABSTRACT FROM AUTHOR]

Source-to-sink tracing of very fine sand supplied to a controversial lower Holocene deltaic lobe in the northeastern Marmara Sea was undertaken using SEM backscatter mapping and quantitative ‘mineral liberation analysis’ of very fine sand fractions. Forty-two samples from the Kurbağalıdere, Göksu, Golden Horn and Riva watersheds, and from Oligo-Miocene outcrops along the southwestern Black Sea coast, show that each of these potential sources has a distinct mineralogical fingerprint. Comparison with 11 samples from the lower Holocene delta and 19 samples from the overlying mud drape show that no single source can account for the mineral proportions in the sand fractions of these depositional sinks, but a mixed provenance provides good matches. For the deltaic lobe, quantitative mixing based on 250,000 Monte Carlo simulations suggests ~ 50% contribution from Oligo-Miocene successions of the southwestern Black Sea coast and inner shelf, ~ 20% contribution from the Göksu stream, and minor contributions from other sources including the Kurbağalıdere stream. This balance of source contributions continued to supply the Holocene mud drape until ~ 6 cal ka, after which local sources became more important. It is hypothesized that unconsolidated sediment from a number of watersheds was parked along the coast of the Neoeuxine Lake and in the paleo-Bosphorus valley during the MIS 2 lowstand. A rising Neoeuxine Lake, possibly swollen by glacial outburst floods from the Altay region of Central Asia, flushed ~ 0.5 km 3 of this sediment through the Strait of Bosphorus to the deltaic lobe and permitted it to rapidly advance into the Marmara Sea, which at that time was rising ~ 1 m each 100 yr. Provenance of the lower portion of the Holocene mud drape is consistent with continued Black Sea outflow throughout the deposition of sapropel M1 in the Marmara Sea. [ABSTRACT FROM AUTHOR]

The sedimentary record in large marine embayments holds important information on Holocene environmental and sea-level changes. This paper investigates the evolution of a large subtropical marine embayment, Maputo Bay, in southern Mozambique. Using a combination of sediment cores, stable isotope data, seismic reflection profiling and 14 C dating, we show complex back-barrier changes during the Holocene and link these to stepped rises in sea level. Our data reveal a sea-level “slowstand” followed by an abrupt rise that we correlate with the 8.2 ka global rise in sea level. Sedimentological, isotope and seismic evidence point to a subsequent slowstand interspersed by two punctuated rises in sea level that formed clear tidal ravinement surfaces. Sedimentary changes in the embayment are primarily forced by sea-level change, whereby tidal ravinement surfaces sandwich normal regressive packages formed via marginal progradation and shallowing of the system during “slow-” or still-stands. Large marine embayment systems hold great potential in unravelling relative sea-level change. Axiomatically, this reduces their utility as archives of climate-change. [ABSTRACT FROM AUTHOR]

The temporal pattern of postglacial rock-slope failure in a glaciated upland area of Ireland (the western margin of the Antrim Lava Group) was evaluated using both 36 Cl exposure dating of surface boulders on run-out debris and 14 C dating of basal organic soils from depressions on the debris. The majority of the 36 Cl ages (~ 21–15 ka) indicate that major failures occurred during or immediately following local deglaciation (~ 18–17 ka). Other ages (~ 14–9 ka) suggest some later, smaller-scale failures during the Lateglacial and/or early Holocene. The 14 C ages (2.36–0.15 cal ka BP) indicate the very late onset of organic accumulation and do not provide close limiting age constraints. Rock-slope failure during or immediately following local deglaciation was probably in response to some combination of glacial debuttressing, slope steepening and paraglacial stress release. Later failures may have been triggered by seismic activity associated with glacio-isostatic crustal uplift and/or permafrost degradation consequent upon climate change. The 36 Cl ages support the findings of previous studies that show the deglacial - Lateglacial period in northwest Ireland and Scotland to have been one of enhanced rock-slope failure. [ABSTRACT FROM AUTHOR]

Slip rates represent the average displacement across a fault over time and are essential to estimating earthquake recurrence for probabilistic seismic hazard assessments. We demonstrate that the slip rate on the western segment of the Puente Hills blind thrust fault system, which is beneath downtown Los Angeles, California (USA), has accelerated from ~0.22 mm/yr in the late Pleistocene to ~1.33 mm/yr in the Holocene. Our analysis is based on syntectonic strata derived from the Los Angeles River, which has continuously buried a fold scarp above the blind thrust. Slip on the fault beneath our field site began during the late-middle Pleistocene and progressively increased into the Holocene. This increase in rate implies that the magnitudes and/or the frequency of earthquakes on this fault segment have increased over time. This challenges the characteristic earthquake model and presents an evolving and potentially increasing seismic hazard to metropolitan Los Angeles. [ABSTRACT FROM AUTHOR]

Coastal plain stratigraphy is often over looked in paleo–sea-level reconstructions because carbonate sediments do not precisely constrain former sea level. Pacific Island sedimentology provides an invaluable record of geomorphic and environmental consequences of coastal evolution in response to changes in sea level and local tectonics. A series of coastal auger cores obtained from eastern ʻUpolu reveal a subsurface carbonate sand envelope predominately composed of coral and coralline algae derived from the reef framework. Coupling the sedimentological record with geophysical models of Holocene sea level, we identify a critical value (0.3–1.0 m) during the falling phase of the sea-level high stand (1899–2103 cal yr BP) that represents the transition from a transgressive to a regressive environment and initiates coastal progradation. Correlating the critical value with time, we observe nearly a millennium of coastal plain development is required before a small human population is established. Our findings support previous studies arguing that Sāmoa was colonized by small and isolated groups, as post–mid-Holocene drawdown in regional sea level produced coastal settings that were morphologically attractive for human settlement. As future sea level approaches mid-Holocene high stand values, lessons learned from Pacific Island sedimentological records may be useful in guiding future decisions related to coastal processes and habitat suitability. [ABSTRACT FROM AUTHOR]

The postglacial European colonization history has come into the focus of biogeographical interest and the study of phylogenetic relatedness within and between regional faunas and floras has proven to be an effective tool for the reconstruction of postglacial colonization trajectories. In the present study, we used a faunal compilation of 2078 European springtail species and data on taxonomic relatedness to investigate whether phylogenetic diversity increases along the gradients from southern glacial refugia towards northern Europe and also whether glacial refugia are phylogenetically segregated, as predicted by models of glacial evolutionary processes and postglacial colonization. In addition, we investigated whether species of restricted range sizes differ in phylogenetic diversity from widespread species as expected by niche models. Proportions of species with restricted range size were highest in glacial refugia, particularly in Spain, as well as on Northern European islands. We found contrasting latitudinal gradients of phylogenetic diversity decreasing in widespread species and increasing in restricted species. Endemic relatedness was negatively correlated with island size. Peaks of phylogenetic diversity in the Pannonian regions and on islands far north indicate a faunal contribution from several glacial refugia and additional refugia north of the Alps, respectively. High phylogenetic clustering in the Iberian Peninsula corroborates models of glacial speciation pulses within major refugia. [ABSTRACT FROM AUTHOR]

The Sechura Desert provides a unique example of a vast palaeo-lagoon system on the Peruvian coast that was active during the first millennium AD. Reconstruction of coastal evolution is made possible by the good resolution of the sedimentary records of the Las Salinas Noroeste coastal plain. Evidence from morphostratigraphy and sedimentary facies indicates marked environmental diversity between the 3rd and the 8th centuries AD and a wide variability of sedimentary dynamics: lagoon foreshores received alternately fine distal marine sediments and coarser continental sediments in pro-deltaic sheets. Evaporation phases periodically occurred in these foreshores causing the formation of salt crusts. After a last high water level in the 8th century AD, the lagoon ultimately dried out and remains dry today. The malacofauna and sedimentary facies indicate that marine marshes bordered by vegetation, perhaps mangrove, developed in the higher parts of these lagoons. This palaeogeography is explained by the progressive build-up of a sand bar which started at least in the middle Holocene. From the 3rd to 8th centuries AD, the lagoon had limited connection to the sea in its northern end and hosted a warm-water and productive ecosystem that was exploited by pre-Hispanic populations. Wetter conditions in the Andes and occasional El Niño rainfalls maintained the lagoon during this period. The freshwater input likely stopped in the 8th century AD, which led to the closing of the shore bar under the influence of the longshore drift rapidly followed by the drying up of the lagoon, and the abandonment of the archaeological site. [ABSTRACT FROM AUTHOR]

Dust deposition in two ombrotrophic peatlands (Baie and Ile du Havre peatland (IDH) bogs) of the Estuary and Gulf of the St. Lawrence in eastern Canada was reconstructed using elemental geochemistry. The rare earth elements (REEs) and other lithogenic element concentrations were measured by ICP-oES and Q-ICP-MS along two peat cores spanning the last 4000 years. Principal component analyses on the geochemical profiles show that REEs display the same behavior as Al, Ti, Sc, and Zr, all conservative elements, which suggests that REEs are immobile in the studied peat bogs and can be used as tracers of dust deposition. Plant macrofossils were also used to infer past environmental and humidity changes. The dust fluxes were reconstructed using the sum of REEs (ΣREE). The range of dust deposition varies from 0.2 to 3.8 g m−2 yr−1 in the Baie bog, while the IDH bog shows lower fluxes ranging between 0.1 and 1.2 g m−2 yr−1. The highest dust fluxes in the Baie bog were recorded from 1750–1000 cal. BP to 600–100 cal. BP and occur at the same time as periods of high variability in the macrofossil record (i.e. successive layers dominated by Sphagnum or Ericaceae). The timing of these events in the dust and macrofossil records also corresponds to documented cold periods. These two periods have been identified as episodes of climatic instability, which could have been caused by changes in the wind regime. [ABSTRACT FROM AUTHOR]

This study investigated the influence of sea-level and climate changes on the decreased fluvial aggradation and subsequent widespread peat initiation in the middle to late-Holocene in the Ishikari lowland, which is a coastal floodplain formed in response to the postglacial sea-level change. By introducing a new approach to separately evaluate the rates of organic and clastic sediment input, we demonstrated that the peat began to form when the fluvial sedimentation rate was significantly decreased (less than 0.6 mm/yr), while plant macrofossil analysis suggested that lowering of water level is also important to the peat initiation. Such changes in sedimentary environment may be associated with the abrupt abandonment of crevasse splays. The concentrated ages of the peat initiation around 5600–5000, 4600–4300, and 4100–3600 cal. BP suggest that an allogenic control promoted the abandonment of crevasse splays, and different onset ages can be explained by different fluvial responses of the Ishikari River and its tributaries. The abandonment of crevasse splays could result from sea-level fall or decreased precipitation. While submillennial sea-level fluctuations coincident with the peat initiation have not been reported in coastal lowlands of Japan, the close comparison of the onset ages and decreased precipitation recorded in a stalagmite from China, which represents the strength of the East Asian summer monsoon (EASM), suggests that decrease in precipitation led to the abandonment of crevasse splays. Our results may indicate that similar fluvial responses might be common in other coastal floodplains affected by the EASM. [ABSTRACT FROM AUTHOR]

Palaeoecological and archaeological studies have demonstrated that human populations have long inhabited the moist forests of central Africa. However, spatial and temporal patterns of human activities have hardly been investigated with satisfactory accuracy. In this study, we propose to characterize past human activities at local scale by using a systematic quantitative and qualitative methodology based on soil charcoal and charred botanical remains. A total of 88 equidistant test-pits were excavated along six transects in two contrasting forest types in southern Cameroon. Charred botanical remains were collected by water-sieving and sorted by type (wood charcoals, oil palm endocarps and unidentified seeds). A total of 50 Accelerator Mass Spectrometry 14C dates were also obtained. Results showed that charred macroremains were found at multiple places in the forest, suggesting scattered human activities, which were distributed into two main periods (Phase A: 2300–1300 BP; Phase B: 580 BP to the present). Charred botanical remains indicated two types of land-use: (1) domestic, with oil palm endocarps most often associated with potsherds (villages) and (2) agricultural, with charcoal as probable remnant of slash-and-burn cultivation (fields). Oil palm endocarp abundance decreased with distance from the identified human settlements. Our methodology allowed documenting, at high resolution, the spatial and temporal patterns of human activities in central African moist forests and could be applied to other tropical contexts. [ABSTRACT FROM AUTHOR]

We present simulations for the late-Holocene glacier advances in the Hailuogou catchment, Gongga Shan, in attempts to test the glacier sensitivity to climate changes and constrain the climate conditions that support these glacier advances. We use a coupled mass-balance and ice-flow model parameterized using empirical glaciological and climatological data to simulate the glacier extents by fitting modeled glaciers to corresponding glacial landforms. The glacier sensitivity test showed that in the Hailuogou catchment, glacier area expands increasingly quickly until 4°C cooling, beyond which decreased expansion occurs up to at least 5°C cooling, but the modeled glacier volume increases steadily up to 5°C with an approximate linear rate being 1.1 × 109 m3/0.5°C. The temperatures were estimated to be 1.9–3.1°C, 1.5–2.6°C, and 1.0–2.2°C cooler than present for the respective Guanjingtai, Hailuogou, and ‘Little Ice Age’ (‘LIA’) Maximum glacial stages, considering a realistic precipitation field being 80–120% of present value. Model results also suggested that the Hailuogou catchment was covered by glaciers of 64.1, 59.3, and 53.8 km2 and ice volumes of 8.79 × 109, 7.99 × 109, and 6.92 × 109 m3 in the Guanjingtai, Hailuogou, and ‘LIA’ Maximum glacial stages, respectively. These findings help to understand the relationships between glacier dynamic and climate change and the hydrological evolution in the Hailuogou catchment. We therefore encourage using the model as a powerful tool to retrieve past ice extents and evaluate their related climate conditions on the vast Tibetan Plateau. [ABSTRACT FROM AUTHOR]

The late Pleistocene Holocene stratigraphic architecture on the northeastern Brazilian continental shelf off the Parnaíba Delta has been explored by high-resolution seismic profiles. The seismic surveys reveal the widespread distribution of incised valleys of different size in offshore continuation of the present-day Parnaiba delta. According to morphology two channel types can be distinguished: U-shaped channels in the eastern part and V-shaped channels in the western part. The stratigraphic successions were grouped into four seismic units separated by different seismic boundaries. The characteristics of the seismic boundaries and internal reflectors of the seismic units were used to distinguish between marine and riverine deposits. The incised-valleys architectural elements were used to link sedimentation processes and variations in base level from late Pleistocene channel avulsion and channel infill in the lowermost course of the paleo-Parnaíba River to marine sediments of the present-day inner shelf. The change of the depositional environments in relation to deglacial sea-level rise is compared to incised valley infills of the Mekong River and Red River systems in Southeast Asia. [ABSTRACT FROM AUTHOR]

Background: Distributions of European fish species were shaped by glaciations and the geological history of river networks until human activities partially abrogated the restrictions of biogeographical regions. The nearby origins of the Rhine, Rhone, Danube and Po rivers in the Swiss Alps allow the examination of historical and human-influenced patterns in fish genetic structure over a small geographic scale. We investigated these patterns in the widespread European chub (Squalius cephalus) from the Rhone, Rhine and Danube catchments and its proposed southern sister species Italian chub (Squalius squalus) from the Po catchment. Results: A phylogenetic tree constructed from mitochondrial Cytochrome b and COI sequences was consistent with earlier work in that it showed a separation of European chub and Italian chub, which was also reflected in microsatellite allele frequencies, morphological traits and shape differences quantified by geometric morphometrics. A new finding was that the predominant mitochondrial haplotype of European chub from the Rhine and Rhone catchments was also discovered in some individuals from Swiss populations of the Italian chub, presumably as a result of human translocation. Consistent with postglacial recolonizations from multiple refugia along the major rivers, the nuclear genetic structure of the European chub largely reflected drainage structure, but it was modified by watershed crossings between Rhine and Rhone near Lake Geneva as well as between Danube and Rhine near Lake Constance. Conclusion: Our study adds new insights into the cyprinid colonization history of central Europe by showing that multiple processes shaped the distribution of different chub lineages around the Swiss Alps. Interestingly, we find evidence that cross-catchment migration has been mediated by unusual geological events such as drainage captures or watershed crossings facilitated by retreating glaciers, as well as evidence that human transport has interfered with the historical distribution of these fish (European chub haplotypes present in the Italian chub). The desirable preservation of evolutionarily distinct lineages will thus require the prevention of further translocations. [ABSTRACT FROM AUTHOR]

Cui, Z.; Schulz-Bull, D.E.; Hou, Y.; Xia, Z., and Waniek, J.J., 2016. Geochemical characteristics and provenance of Holocene sediments (core STAT22) in the Beibu Gulf, South China Sea. Geochemical investigations of the core sediments STAT22 from the Beibu Gulf, South China Sea, were carried out to understand the provenance of the Holocene sediments. Geochemical indices of La/Co, La/Sc, and Zr/Ti ratios, combined with distribution patterns of rare earth elements, suggest that the western Hainan Island was the main provenance of the core sediments. The eastern Qiongzhou Strait was also an important source of the sediments at the core location, but its contributions varied spatially and temporally with strait formation and evolution. With the opening of the Qiongzhou Strait, the provenance and hydrodynamic conditions of the Beibu Gulf underwent a significant change. Around 4500 YBP, the materials from the eastern area of the Qiongzhou Strait were transported into the study area and hence became one of the important sources for the core sediments. In contrast, Red River contributed little to the core sediments during the entire Holocene. Thus, with sea-level fluctuation, the depositional environment in the Beibu Gulf significantly changed during the Holocene. [ABSTRACT FROM AUTHOR]

In this article, the author comment on a study conducted by J. Bourgois and colleagues on cosmogenic isotope concentration data for the postglacial evolution of Lago General Carrera/Buenos Aires, Argentina. Topics discussed include velocities of postglacial rebound following the appearance of shorelines, elevation of shorelines by using Shuttle Radar Topography Mission (SRTM) data, and effect of climate change on endorheic lakes.

The Ombrone palaeovalley was incised during the last glacial sea-level fall and was infilled during the subsequent Late-glacial to Holocene transgression. A detailed sedimentological and stratigraphic study of two cores along the palaeovalley axis led to reconstruction of the post-Last Glacial Maximum valley-fill history. Stratigraphic correlations show remarkable similarity in the Late-glacial to early-Holocene succession, but discrepancy in the Holocene portion of the valley fill. Above the palaeovalley floor, about 60 m below sea-level, Late-glacial sedimentation is recorded by an unusually thick alluvial succession dated back to ca 18 cal kyr bp. The Holocene onset was followed by the retrogradational shift from alluvial to coastal facies. In seaward core OM1, the transition from inner to outer estuarine environments marks the maximum deepening of the system. By comparison, in landward core OM2, the emplacement of estuarine conditions was interrupted by renewed continental sedimentation. Swamp to lacustrine facies, stratigraphically equivalent to the fully estuarine facies of core OM1, represent the proximal expression of the maximum flooding zone. This succession reflects location in a confined segment of the valley, just landward of the confluence with a tributary valley. It is likely that sudden sediment input from the tributary produced a topographic threshold, damming the main valley course and isolating its landward segment from the sea. The seaward portion of the Ombrone palaeovalley presents the typical estuarine backfilling succession of allogenically controlled incised valleys. In contrast, in the landward portion of the system, local dynamics completely overwhelmed the sea-level signal, following marine ingression. This study highlights the complexity of palaeovalley systems, where local morphologies, changes in catchment areas, drainage systems and tributary valleys may produce facies patterns significantly different from the general stratigraphic organization depicted by traditional sequence-stratigraphic models. [ABSTRACT FROM AUTHOR]

Detrital zircons from Holocene beach sand and igneous zircons from the Cretaceous syenite forming Cape Sines (Western Iberian margin) were dated using laser ablation - inductively coupled plasma - mass spectrometry. The U-Pb ages obtained were used for comparison with previous radiometric data from Carboniferous greywacke, Pliocene-Pleistocene sand and Cretaceous syenite forming the sea cliff at Cape Sines and the contiguous coast. New U-Pb dating of igneous morphologically simple and complex zircons from the syenite of the Sines pluton suggests that the history of zircon crystallization was more extensive ( ca 87 to 74 Ma), in contrast to the findings of previous geochronology studies ( ca 76 to 74 Ma). The U-Pb ages obtained in Holocene sand revealed a wide interval, ranging from the Cretaceous to the Archean, with predominance of Cretaceous (37%), Palaeozoic (35%) and Neoproterozoic (19%) detrital-zircon ages. The paucity of round to sub-rounded grains seems to indicate a short transportation history for most of the Cretaceous zircons ( ca 95 to 73 Ma) which are more abundant in the beach sand that was sampled south of Cape Sines. Comparative analysis using the Kolmogorov-Smirnov statistical method, analysing sub-populations separately, suggests that the zircon populations of the Carboniferous and Cretaceous rocks forming the sea cliff were reproduced faithfully in Quaternary sand, indicating sediment recycling. The similarity of the pre-Cretaceous ages (> ca 280 Ma) of detrital zircons found in Holocene sand, as compared with Carboniferous greywacke and Pliocene-Pleistocene sand, provides support for the hypothesis that detritus was reworked into the beach from older sedimentary rocks exposed along the sea cliff. The largest percentage of Cretaceous zircons (< ca 95 Ma) found in Holocene sand, as compared with Pliocene-Pleistocene sand (secondary recycled source), suggests that the Sines pluton was the one of the primary sources that became progressively more exposed to erosion during Quaternary uplift. This work highlights the application of the Kolmogorov-Smirnov method in comparison of zircon age populations used to identify provenance and sediment recycling in modern and ancient detrital sedimentary sequences. [ABSTRACT FROM AUTHOR]

Carbonate pedofeatures of three chernozemic soils developed from loesslike loams in the foreststeppe zone of Lipetsk oblast under fallow plot (Luvic Chernozem (Clayic, Pachic)) and under forest (Calcic Chernozem (Clayic, Pachic)) and in the steppe zone of Dnepropetrovsk oblast (Calcic Chernozem (Episiltic, Endoclayic, Pachic)) were studied in the field and laboratory with the use of a set of methods, including the radiocarbon method, mass spectrometry, and micro- and submicromorphology. The morphological diversity of carbonate pedofeatures in these soils was represented by carbonate veins, coatings, disperse carbonates (carbonate impregnations), soft masses (beloglazka), and concretions. In the forest-steppe soils, disperse carbonates and soft masses were absent. The radiocarbon age of carbonate pedofeatures in the forest-steppe soils varied within a relatively narrow range of 3-4.3 ka cal BP with a tendency for a younger age of carbonate concretions subjected to destruction (geodes). In the steppe chernozem, this range was larger, and the C ages of different forms of carbonate pedofeatures were different. Thus, soft masses (beloglazka) had the age of 5.5-6 ka cal BP; disperse carbonates, 17.5-18.5 ka cal BP; and hard carbonate concretions, 26-27 ka cal BP. Data on δC demonstrated that the isotopic composition of carbon in virtually all the 'nonlabile' carbonate pedofeatures does not correspond to the isotopic composition of carbon of the modern soil organic matter. It was shown that the studied chernozemic soils are polygenetic formations containing carbonate pedofeatures of different ages: (a) recent (currently growing), (b) relict, and (c) inherited pedofeatures. The latter group represents complex pedofeatures that include ancient fragments integrated in younger pedofeatures, e.g., the Holocene soft carbonate nodules with inclusions of fragments of the ancient microcodium. [ABSTRACT FROM AUTHOR]