The occurrences of sepiolite beds and nodules in alkaline and saline Miocene Eskisehir lake deposits provide unique examples of ancient lacustrine environments. Stockwork-type magnesite deposits, which were formed very close to the Miocene lake, served as parent rocks for sepiolite nodules (meerschaum). The Miocene succession consists of calcareous clay, clayey carbonate, dolomite, a gypsum-bearing calcareous clay series, siliceous tuffs, sepiolite beds, sepiolite-bearing dolomite, and basal conglomerates of ultramafic rocks. Sepiolite beds were deposited by direct precipitation from Si-supersaturated lake water under alkaline and saline conditions. They are underlain by a gypsum series. Organic matter-rich sepiolites suggest the presence of water stratification with anoxic bottom waters, which developed due to high sulphate input at the base from the ascending hydrothermal solutions along the fracture systems with extensive fresh water input near to the surface. Sepiolite nodules resulted from diagenetic replacement of magnesite pebbles at shallow burial under alkaline conditions in the vicinity of paleo-shorelines. Sepiolite beds were deposited in three ways: 1) black (up to 2.8 wt. % TOC) sepiolite beds rich in organic matter accumulated in an anaerobic paleoenvironment; 2) brown (about 0.5 wt. % TOC) sepiolite beds poor in organic matter, containing minor amounts of white, 2–6 mm long, discontinuous, and very soft dolomite laminae formed in a dysaerobic paleoenvironment; and 3) white dolomitic sepiolite beds in which dolomite content is about 20–40% in an aerobic paleoenvironment.

Cyclic dolomite and gypsum series indicate hypersaline-evaporative paleoenvironments with rapid changes in lake water chemistry. These cyclic evaporatic conditions are also related to cyclic changes in water depth. Based on X-ray powder diffraction data, except degree of crystallinity, no mineralogic difference was found between sepiolite in beds and nodules. SEM studies revealed fibers about 0.2 µm wide and up to 30 µm long in sepiolite beds; crystals less than 5 µm long with bent tips; and a more compacted appearance in sepiolite nodules.

The depositional history of the Bonneville Salt Flats, a perennial saline pan in Utah's Bonneville basin, has poor temporal constraints, and the climatic and geomorphic conditions that led to saline pan formation there are poorly understood. We explore the late Pleistocene to Holocene depositional record of Bonneville Salt Flats cores. Our data challenge the assumption that the saline pan formed from the desiccation of Lake Bonneville, the largest late Pleistocene lake in the Great Basin, which covered this area from 30 to 13 cal ka BP. We test two hypotheses: whether climatic transitions from (1) wet to arid or (2) arid to wet led to saline pan deposition. We describe the depositional record with radiocarbon dating, sedimentological structures, mineralogy, diatom, ostracode, and portable X-ray fluorescence spectrometer measurements. Gypsum and carbonate strontium isotope ratio measurements reflect changes in water sources. Three shallow saline lake to desiccation cycles occurred from >45 and >28 cal ka BP. Deflation removed Lake Bonneville sediments between 13 and 8.3 cal ka BP. Gypsum deposition spanned 8.3 to 5.4 cal ka BP, while the oldest halite interval formed from 5.4 to 3.5 cal ka BP during a wetter period. These findings offer valuable insights for sedimentologists, archaeologists, geomorphologists, and land managers.

Soft-sediment deformation structures (SSDS) were identified in proglacial lacustrine (glaciolacustrine) sediments dated to 25–24 ka in the Buivydžiai outcrop, situated 30 km north of Vilnius in east Lithuania. These sediments accumulated in front of the last Weichselian glaciation maximum. The SSDS originated due to sandy silt liquefaction that disrupted the decimeter-thick silty sand interlayer. A NW-SE trending Buivydžiai fault was mapped in the proximity (8 km) of the Buivydžiai outcrop. The fault is well traced by a dense drilling in the sediments of the preglacial Daumantai Formation in the basal part of the Quaternary cover and attributed to the earliest Pleistocene. Depth difference of the formation along the fault is ~5–8 m; the northern flank is relatively uplifted with respect to the southern flank. The Buivydžiai earthquake was most likely induced by formation of an elastic forebulge flexure of the Earth's crust in front of the ice sheet. The magnitude was evaluated ~M = 6.0–6.5 and was most likely of shallow hypocenter depth. Furthermore, the Bystritsa (Belarus) earthquake of magnitude M = 3.5–4.0 was registered in December 1908 to the east (12 km) of the Buivydžiai outcrop along the Buivydžiai fault, which points to recurrent seismic activity of this fault.

We describe aggregative microconchid (Lophophorata) tubes from the uppermost Permian (upper Changhsingian) and Lower Triassic (Olenekian) lacustrine and fluvial strata of the Tunguska and Kuznetsk basins and the southern Cis-Urals, Russia. These attach to clam shrimp carapaces, bivalve shells, terrestrial plant fragments and a horseshoe crab head shield, and also form their own monospecific agglomerations. Planispiral tubes of a wide size range (0.1–2.5 mm) create dense settlements on these firm substrates, which likely comprise multiple generations of the same species. These finds confirm that this extinct lophophorate group was inhabiting non-marine continental basins during latest Permian and earliest Triassic time, when they were major suspension feeders in such limnic ecosystems. Microconchids dispersed extensively and rapidly in the aftermath of the Permian–Triassic mass extinction into both marine and continental basins at low and moderately high latitudes, which were notably different in salinity, temperature, depth and redox conditions. This confirms that small lightly calcified microconchids were a genuine disaster eurytopic group, whose expansion may have been promoted by low predator pressure and low competition for substrate.

The mineralogy of the Neogene lacustrine facies of Pelitçik basin was investigated for the purpose of deriving the palaeoenvironmental parameters of this intervolcanic basin. The laboratory studies indicate that dolomite and K-feldspar are the major non-clay minerals in the study area, where plagioclase, analcime, fibrous zeolite and quartz are the minor constituents. Dolomites are found to be non-stoichiometric in chemistry. The clay fraction of the lacustrine facies is composed mainly of dioctahedral smectites. The smectites are rich in Al-Fe indicating a detrital origin. Illite comprises a minor contribution to the clay fraction, where chlorite and kaolinite are found in trace amounts. Based on dolomite stoichiometry and the mineral paragenesis found in the Pelitçik basin, the depositional conditions are suggested to have been a shallow, quiet, perennial lacustrine environment with fresh to slightly saline and slightly alkaline water chemistry. In addition, based on geological and mineralogical constraints, it is suggested that the water chemistry fluctuated during the deposition of the Pazar formation and the lake began its evolution with a hydrologically closed system and completed its evolution with a hydrologically open system.

Alkali- and Ca-rich smectites occur in association with Neogene lacustrine sedimentary rocks and high-K calc-alkaline volcanic rocks with compositions ranging from andesite to rhyolite in western Anatolia (Turkey). Major clay occurrences are associated predominantly with the Foça and Akçaköy ignimbrites and with the ignimbrites within the Rahmanlar pyroclastics. Experimental studies indicate that the main clay minerals present are Na- and Ca-smectite and subordinate illite, associated with silica polymorphs, trace clinoptilolite and chlorite. The authigenic minerals formed by weathering and metasomatic reactions between hot volcanic material and lake water. Smectite was produced as a result of argillic alteration of the volcanic glass and feldspars of the ignimbrites, Rahmanlar pyroclastics and reworked volcaniclastic sediments through chemical weathering and dissolution-precipitation processes and formed as authigenic phases both in terrestrial and nearby shallow lacustrine environments under prevalent humid or semi-humid climate during the Neogene.

Mg-silicate minerals (e.g., stevensite, kerolite, talc, sepiolite) play an important role in the construction of facies models in lacustrine and peri-marine environments because they are sensitive to changes in solution chemistry. However, the response of Mg-silicate mineralogy to changing aqueous chemistry is only broadly understood because the mechanisms underpinning the coprecipitation of Mg2+ and SiO2(aq) from surface water, and subsequent Mg-silicate crystallization, are unclear. Here we describe the results of experiments designed to systematically examine the effects of pH, Mg/Si and salinity of the parent solution on the nature of initially precipitated products. Structural interrogation of the products with X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and thermal analysis (TGA/DTA) allow comparison of synthetic products with naturally occurring crystalline counterparts. In general, Mg2+ and SiO2(aq) co-precipitation and nucleation of Mg-silicate layer structures first involves the rapid formation of 2:1 layers with trioctahedral occupancy and a mean coherent X-ray scattering domain between 1–2 unit cells with respect to the c axis. Well defined but diffuse hk reflections indicate two-dimensional growth, turbostratic stacking and highly variable interlayer hydration. Diffuse reflectance FTIR shows numerous structural similarities with stevensite, kerolite and sepiolite. However, TGA/DTA analysis indicates the presence of variable kerolite/stevensite interstratification not readily detectable through XRD analyses, as well as a significant degree of surface and interlayer hydration (e.g. 15–20 wt.%).

We observe a number of clear trends in the products with respect to solution chemistry. For example, at low salinity, kerolite-like products dominate at high Mg/Si and high pH, whereas sepiolite-like products are formed at lower pH and lower Mg/Si. At high salinity and high Mg/Si, stevensite-like products are favoured at high pH and kerolite-like products dominate at lower pH, whereas a decrease in Mg/Si of the solution leads to sepiolite-like products at low pH and only stevensite-like products at high pH. Higher pH leads to an increase in octahedral vacancies which favour stevensite-like products; this may result from a higher rate of two-dimensional tetrahedral sheet expansion relative to the octahedral sheet, as inferred from studies of silica oligomerization and brucite growth kinetics.

Together, our results indicate that the neoformation of Mg-rich silicates from solution may often begin with the rapid nucleation of hydrated 2:1 layers. Subsequent dehydration leads to progressive layer stacking order and could occur in response to wetting/drying cycles, prolonged exposure to high salinity solutions, or burial and heating. The surface and interlayer water associated with these products is undoubtedly an important source of diagenetic water in Mg-silicate-bearing successions, and the chemistry of this water upon later diagenesis should be a focus of future investigation.

The Rb, Sr, and Ti content, Rb/Sr ratio, grain size, magnetic susceptibility, and magnetic fabric in sediments of the BZK1 core were utilized to reconstruct the evolution of the climatic environment in the Chaohu Lake Basin between the last deglacial and the early Holocene. Multi-proxy analyses indicate that lacustrine sediments in Chaohu Lake clearly record the Bølling-Allerød interstadial, the Younger Dryas event and dry-cold climate events occurring between 10.7 cal ka BP and 10.5 cal ka BP. At approximately 15.6–14.8 cal ka BP, the waters became deeper and the climate turned cool. The climate subsequently shifted to a relatively humid period and the lake was largest from 14.8 to 12.8 cal ka BP. From 12.8 to 11.7 cal ka BP, the climate abruptly turned dry and cold and the lake shrank to its lowest level. During 11.7–10.7 cal ka BP, the climate became relatively humid but, from approximately 10.7 to 10.5 cal ka BP, suddenly reverted to a dry and cold state. These climatic change records suggest that lacustrine sediments from the Chaohu Lake Basin in the lower Yangtze region responded actively to global climate changes, comparable with the environmental records from stalagmites and other lacustrine sediments in the region.

The Ullum-Zonda tectonic depression located in the central Andes Precordillera records several lacustrine episodes from frequent natural damming of the San Juan River during the late Quaternary. We analyzed stratigraphic, geomorphic, and geologic data and obtained new radiocarbon ages for Paleolake Ullum-Zonda. Results show the existence of a late Pleistocene age (16.7–15.2 ka BP) unit and an early to middle Holocene (9475–7685 yr BP) unit. Subsurface data show lacustrine episodes were common during the late Pleistocene, with probably nine episodes occurring during that period. Two transgressive events are evident in the Holocene unit, dated to ~8420±30 and shortly after 7460±30 14C yr BP. The maximum extent of the paleolake occurred at 6930±30 14C yr BP, shortly before the lake desiccated. Fault propagation folds and growth strata in Quaternary alluvial deposits relate to the Villicum-Zonda Fault and may indicate early to middle Holocene activity for this fault. The deformation observed in an ancient shoreline of the paleolake could be related to middle to late Holocene activity of the Cerro Zonda Norte Fault at a mean vertical uplift rate of ~0.8 mm/yr in the hanging wall block.

This paper presents new evidence from the Dhamar highlands, Yemen, of paleohydrologic response to fluctuations in Holocene climate. Stratigraphic, geochemical, and chronological analyses of highland peat and lacustrine deposits contribute to knowledge of the timing of early Holocene moisture changes on the Arabian Peninsula, providing a backdrop to understanding early cultural development in the Arabian highlands. The location of the Dhamar highlands, characterized by intermontane valleys surrounded by the highest mountains on the Arabian Peninsula and adjacent to the Indian Ocean is ideal for examining the influence of the Indian Ocean Monsoon (IOM) on the moisture history of this region. Fluctuations in the lacustrine and paleosol records of the Dhamar highlands reflect both local changes in paleohydrology and regional influences on the Holocene paleoclimatic conditions in southwest Arabia. In addition, a peat deposit with a radiocarbon age of 10,253 ± 10,560 cal yr BP documents some of the earliest Holocene high moisture conditions on the Arabian Peninsula.

Spores of the dung fungus Sporormiella have been suggested to indicate the presence, perhaps also the abundance of past megaherbivore populations. Nonetheless, basic studies demonstrating a correlation between Sporormiella concentration in lacustrine sediments and modern herbivore abundance are lacking. This study of Sporormiella representation in grazed and ungrazed landscapes provides supporting evidence for the application of Sporormiella as an indicator of megaherbivore presence and abundance in ancient landscapes. However, Sporormiella representation is spatially sensitive to the distance from the dung source. In lakes where Sporomiella are abundant in shoreline sediments, they decline sharply with increasing distance from the lake edge. Although this study provides supporting evidence for the application of Sporormiella as a proxy for herbivore presence and abundance, independent proxies should be applied in conjunction with Sporormiella to control for changes in lake size.

Palynological and sedimentological data from Lake Telmen, in north-central Mongolia, permit qualitative reconstruction of relative changes in moisture balance throughout the mid to late Holocene. The climate of the Atlantic period (7500–4500 yr ago) was relatively arid, indicating that Lake Telmen lay beyond the region of enhanced precipitation delivered by the expanded Asian monsoon. Maximum humidity is recorded between ∼4500 and 1600 cal yr B.P., during the Subboreal (4500–2500 yr ago) and early Subatlantic (2500 yr–present) periods. Additional humid intervals during the Medieval Warm Epoch (∼1000–1300 A.D. or 950–650 ago) and the Little Ice Age (1500– 1900 A.D. or 450–50 yr B.P.) demonstrate the lack of long-term correlation between temperature and moisture availability in this region. A brief aridification centered around 1410 cal yr B.P. encompasses a decade of cold temperatures and summer frost between A.D. 536 and 545 (1414–1405 yr B.P.) inferred from records of Mongolian tree-ring widths. These data suggest that steppe vegetation of the Lake Telmen region is sensitive to centennial- and decadal-scale climatic perturbations.

The form of microbialite accumulations is largely the product of environmental processes and microbial activity. Recent work has largely concentrated on the identification and classification of microbialites with little attention being paid to their environmental significance. This study describes the environmental distribution of the varied stromatolite forms recorded from the Middle Old Red Sandstone sequences of the Orcadian Basin. Comparisons are made with Triassic examples from East Greenland and modern microbialite accumulations. The Middle Old Red Sandstone of Northern Scotland was deposited in a predominantly lacustrine setting. Stromatolites are recorded from both steep basin margin coincident settings and lower gradient settings where the lake margin was distant from the basin margin. In the latter case stromatolite development is largely restricted to transgressive lacustrine sequences, during the deposition of which reduced rates of sedimentation resulted from the migration of sediment input points towards the basin margin. Stromatolite sheets, domal mounds, aligned mounds (and associated runnels), sand-cored stromatolite mounds and reefal stromatolite accumulations have been identified representing the transition from more sheltered to more exposed environments. In basin margin coincident settings stromatolite accumulation is restricted to areas of low sedimentation where microbialites coat boulders and pebbles. A model for the palaeoenvironmental distribution of the stromatolite forms described is proposed and is shown to be applicable to similar examples from the Triassic of East Greenland. It is suggested that this model may be more widely applicable to stromatolitic accumulations in similar lacustrine settings through large portions of the Phanerozoic.

We used a combination of radiocarbon and OSL dating in ice-proximal lacustrine silt and clay and outwash sand to estimate when ice of the Green Bay Lobe of the Laurentide Ice Sheet began retreating from its maximum position in south-central Wisconsin. The radiocarbon ages indicate that lakes had formed in the two tributary valleys by ~ 17.2 and 20.1 ka, respectively. The OSL ages indicate that the Green Bay Lobe was at its maximum position from about 26.4 ± 5.1 ka to 21.4 ± 3.3 ka. These data provide entirely new chronologic control on late Wisconsin (Marine Isotope Stage 2) glacial event in the upper Midwest, as well as the opportunity to directly compare radiocarbon and OSL ages in this setting.

Studies in submerged prehistoric archaeology have gained momentum in recent years with particular focus on the inundated landscapes of the European continental shelf. Although this renewed interest lies primarily in modern coasts and seas, there are a variety of differences between the submerged prehistoric archaeologies of inland and marine environments, ranging from questions of scientific research to heritage management to practical field methods. Some of these differences are the result of location, function, and period. Despite this, there exist similarities that, if ignored, risk increased marginalization of the archaeology of submerged landscapes from the greater field of prehistoric archaeology. A holistic evaluation of prehistoric archaeological landscapes must include inland waters and coastal zones and their relationships. Aquatic environments, viewed both as individual locations as well as continuous and connecting waterways, are introduced for their differences and similarities, and simplified examples of material and legislation are introduced in order to contextualize submarine sites and practices within the greater fields of prehistory and underwater archaeology.

The late Quaternary glacial history of the Amery Oasis, and Prince Charles Mountains is of significant interest because about 10% of the total modern Antarctic ice outflow is discharged via the adjacent Lambert Glacier system. A glacial thrust moraine sequence deposited along the northern shoreline of Radok Lake between 20–10 ka bp, overlies a layer of thin, aragonite crusts which provide important constraints on the glacial history of the Amery Oasis. The modern Radok Lake is fed by the terminal meltwaters of the alpine Battye Glacier. The aragonite crusts were deposited in shallow water of ancestral Radok Lake 53 ka bp, during the A3 warm event in Isotope Stage 3. Oxygen isotope (δ18O) analysis of the last glacial-age aragonite crusts indicates that they precipitated from freshwater with a δ18OSMOW composition of -36%, which is 8% more depleted than the present water (-28%) in Radok Lake. A regional oxygen isotope (δ18O) and elevation relationship for snow is used to determine the source of meltwater and glacial ice in Radok Lake during the A3 warm event. This relationship indicates that Radok Lake received meltwater from the confluence of both Battye Glacier ice and an expansion of grounded western Lambert Glacier ice in the Amery embayment.

The clastic sequence of the Ergiliin Zoo Formation stretches along the Mongolian–Chinese border in the southern Gobi Desert, Mongolia. Its members (Sevkhuul, Ergil) exposed in the Erdene Sum region are well known for their vertebrate remains of Late Eocene and Oligocene age. Based upon field work, the continental red beds were subdivided into four units described as (I) prodelta/mud-sand flat, (II) delta front, (III) delta plain and (IV) calcretes. All sub-environments are in a fluvial–lacustrine setting. Electronmicroprobe analysis, in addition to conventional thin-section examination, was applied to shed some light on the complex mineral association made up of light minerals (quartz, plagioclase, ternary feldspar, orthoclase, smectite, illite, rare palygorskite), heavy minerals (almandine–pyrope solid solution series, zoisite–epidote s.s.s.) and abundant goethite and carbonate minerals (calcite, dolomite). Igneous rocks being exposed in the source area have contributed to the formation of carbonate minerals and Mg-bearing sheet silicates during diagenesis. Higher up on the delta plain transitional between distal alluvial and deltaic deposits, fluids emerged from the distal alluvial–fluvial deposits and formed calcareous duricrusts. Drawing conclusions from the rock colour, the mineral assemblage and the palaeoecological data, the climatic conditions may be described as alternating wet and dry seasons, closely resembling those conditions of a modern savannah.

Paleolimnology provides information on the past chemical, physical and biological nature of water bodies. In polar regions, where global climatic changes can be exacerbated compared with lower latitudes, the science has become important for reconstructing past changes and in so doing, predicting possible effects of future changes. Owing to the association of life with water bodies, particularly stable water bodies sustained over many millennia, paleolake regions on the surface of Mars are of exobiological importance. In this mini-review, we use experience gathered in the High Arctic to describe the importance of paleolimnology in the Earth's polar regions as it pertains to the future application of this science to robotic and human exploration missions to the planet Mars.

The study is based on over 170 bivalve specimens collected in the last seven years by three independent collectors in basal Westphalian D strata at Piesberg Quarry, near Osnabrück, northern Germany. All the material has come from the roof shales of either the Bänkchen or the Dreibänke coal, 25 m above it, most of it from above the Dreibanke coal. Both faunal bands have closely similar sediments, shells and floral associations, mainly of hydrophyllic plants, including those that characterise waterlogged swamps. The palaeoenvironments were, on average, of low energy deltaic lakes.

Both faunal bands constitute life assemblages of small, sparse Anthraconaia mingled with abundant plants and plant debris in richly carbonaceous shale with a variable carbonate content. Siphonal and pedal gapes of the valves indicate that the bivalves lived in a steeply burrowing position probably below the surface of the sediments. After death most valve pairs lay with their median planes parallel to the bedding planes of the sediment. Later overlying pressure, normal to bedding planes and varying according to the time of carbonate formation, led to a pattern of breakdown of the convexity of the shells essentially the same as that found in larger Anthraconaia in Westphalian B. In both cases it appears that lateral profiles of shells have been unaffected by vertical crushing. It is therefore reasonable to treat the profiles of uncrushed and vertically crushed shells together.

On the basis of measurements and morphology two groups of shells have been distinguished at Piesberg, that of Anthraconaia pruvosti (Tchernychev) Weir, comprising about 96 per cent of the fauna, and the remainder Anthraconaia piesbergensis sp. nov. Each is illustrated by a variation diagram or pictograph and is in part defined by growth equations in terms of shell length, height and anterior end. The small A. piesbergensis, which also yields evidence of posterior gape, is formally described. Anthraconaia pruvosti, which has not been previously recorded in Germany, shows extremely wide variation with a number of new varieties, but all intergrade with previously known varieties of this species and include Anthraconaia weissiana (Geinitz). The mean size of the shells is half that of the holotype, from northern France, but size ranges are comparable with those from the U.K. The mode of the fauna lies around small, elongate, subtriangular shells with nearly straight to slightly reflected ventral margins.

The elements of the Piesberg fauna fall into place stratigraphically in the sequence of Anthraconaia faunas in Westphalian C to late Westphalian D, mainly in the southern part of the U.K. Moreover, very small, scarce shells recently described above No. 10 coal, late Westphalian D at Writhlington, Somerset, U.K., appear related to A. piesbergensis. At this horizon they had different associates and a different palaeohabitat from those of the larger Anthraconaia pringlei (Dix & Trueman) which succeeded A. pruvosti. It is therefore likely that A. piesbergensis may have occupied a different palaeoecological niche from that of A. pruvosti and that A. piesbergensis was collected from a horizon slightly different from those yielding A. pruvosti at Piesberg Quarry, possibly from a fauna which lived in shallower water.

Re-figuring of uncrushed, excellently preserved material of Anthraconaia aff. pruvosti from late Westphalian C of Pembrokeshire, SW Wales, reveals new evidence of the musculature of the genus Anthraconaia. There is also clear evidence of siphonal and pedal gapes in closed valves, both being features previously unrecognised in Anthraconaia, and characteristic, to date, only of Westphalian late C and D Stages in Germany and the U.K.