The Serinhisar-Acıpayam basin of western Anatolia hosts a Neogene alkaline lake which formed in some graben and semi-graben depression zones as a result of N–S tension. The basin is filled with fluvial and lacustrine sediments dominated by clayey materials. The filling of the basin with fine sediments and associated water level changes caused the development of swampy and/or semi-swampy, alkaline-lake environments where sepiolite, palygorskite, saponite and dolomitic sepiolite or palygorskite precipitated periodically in the basin. Sepiolite is predominant in the Kuyucak section and is intercalated with saponite-dominated levels, whereas saponite accompanied palygorskite at Kocapınar where basaltic volcanism occurred. The contacts between sepiolite-palygorskite and saponite levels are more or less sharp, reflecting rapid changes in the physicochemical conditions of the depositional environment. Micromorphological images reveal that both sepiolite and palygorskite grew as interwoven fibers or fiber bundles and masses where dolomite was absent, indicating direct precipitation from solution, whereas fibrous networks grew authigenically on and out of dolomite in dolomitic sepiolite and dolomitic palygorskite. Saponite is either green or reddish brown due to its organic material-rich content and derivation from products of basaltic volcanism. Synsedimentary basaltic volcanism was the main source of Fe and Al, whereas Si and Mg were derived from surrounding ultrabasic and detrital units and partly from the volcanism. It can be concluded that sepiolite, palygorskite and saponite formed either by direct precipitation from alkaline lake water or authigenically from interstitial pore-water between dolomite rhombs as controlled by concentration of Si, Mg, Al and Fe, rather than by mutual transformation.

Pliocene volcaniclastic lacustrine rocks of the Doğanbey formation in the Beyşehir region (central Anatolia) are composed of organic-matter-bearing claystone, clastic units and dolomite interbeds, suggesting an anaerobic, shallow swampy, lacustrine depositional environment. The depositional environment was subjected to periodic climatic change during which diagenesis occurred, and smectite, and locally palygorskite, were precipitated. Smectite flakes formed authigenically on feldspar and palygorskite fibers between dolomite rhombs and at the edges of smectite flakes. Increases in leaching of Na, K, Sr, Ba and Rb, increasing Al/Si ratios, and Fe with increasing degree of alteration reveal that hydration of volcaniclastic grains (feldspar, glass) by meteoric water — determined from O and H isotopic values — was the main cause of precipitation of beidellite and montmorillonite based on the tetrahedral charge/octahedral charge ratio, with average structural formulae of (Si7.72Al0.28)(Al3.20Fe0.53Mg0.25 Mn0.02Ti0.04) (Ca0.11Na0.09K0.11), and (Si7.88Al0.13)(Al3.18Fe0.53Mg0.18Mn0.02Ti0.05)(Ca0.11Na0.11K0.09), respectively. Therefore, the Doğanbey-area smectite is presumed to have formed by chemical weathering and dissolution-precipitation from feldspar and glass during diagenesis; palygorskite formed by direct precipitation from Mg-rich solutions during dolomitization, and by transformation from smectite in an alkaline lacustrine environment.

A high-resolution multiproxy lake sediment dataset, comprising lithology, radiography, μXRF elemental, magnetic susceptibility (MS), δ13C, and δ18O measurements since ca. AD 400 is presented in this study. Changes in lithology, radiography, magnetic susceptibility (MS), δ13C, and δ18O reflect wet/dry climate periods, whereas variability in log(Ca/K) can reflect warm/cold climate periods. Analyses of the multiproxy results allow the distinction of several climate periods, which may be associated with climatic phenomena such as changes in North Atlantic Oscillation (NAO) and/or solar activity. The influence of NAO−/NAO+ (negative/positive) is suggested to be related with the southward/northward displacement of the storm tracks resulting from the NAO−/NAO+ phases. For solar activity, the influence is explained through a direct increase in solar heating leading to calcite precipitation. The Dark Ages Cold Period (DACP, AD 450–750) reflects cold-dry climate conditions at this site, indicative of a positive North Atlantic Oscillation (NAO+) and low solar activity. The Medieval Climate Anomaly (MCA, AD 950–1250) exhibits wet-dry-wet and warm-cold-warm climate conditions. The wet/dry periods likely are associated with NAO−/NAO+, respectively, and the warm/cold period may reflect relatively high/low solar activity. The Little Ice Age (LIA, AD 1400–1850) is characterized by dry and cold climate conditions, suggesting the influence of NAO+ and low solar activity. Comparison of the results of this study with local and regional results suggests a generally similar climate pattern, which is indicative of similar climate mechanisms. The contradictions can be associated with age-related uncertainties, orographic differences, and/or other regional teleconnections.

Core OL-97A, retrieved from the depocenter of Owens Lake, represents a depositional history spanning the past 1000 yr. Among the 17 elements analyzed in the acid-leachable fractions of 315 salt-free samples (at ∼3 yr/sample), Mg and Li, which come chiefly from authigenic Mg-hydroxy-silicates, were found to have concentration variations reflecting lake salinity and climatic changes during the past. A total of 231 isotopic measurements on carbonates from the same samples in the upper 181 cm show that δ18O and δ13C values range from −5.66 to 0.12‰ (PDB) and 1.38 to 4.28‰ (PDB), respectively. The rate of change with time in δ18O records the rate of change in lake's volume due to climate fluctuations, whereas variations in δ13C reflect mainly variations in biological productivity, nutrient supply, and dissolved carbonate in the lake. Results indicate an effectively dry climate between A.D. 950 and 1220, corresponding to the Medieval Climatic Anomaly (a warm period in northern Europe), during which Owens Lake approached playa conditions. Wet climates prevailed during A.D. 1220–1480, producing relatively large and deep lakes. Beginning about A.D. 1550, the regional climate turned colder but had frequently oscillating precipitation. Six wet/dry cycles with ∼50-yr duration occurred between A.D. 1480 and 1760, during the later half of which Owens Lake became a playa. Since ∼A.D. 1880, the lake level has steadily dropped from its historic high stand under strong impact of human activity.

Authigenic calcite silts at Wadi Midauwara in Kharga Oasis, Egypt, indicate the prolonged presence of surface water during the Marine Isotope Stage 5e pluvial phase recognized across North Africa. Exposed over an area of ∼ 4.25 km2, these silts record the ponding of water derived from springs along the Libyan Plateau escarpment and from surface drainage. The δ18O values of these lacustrine carbonates (− 11.3‰ to − 8.0‰ PDB), are too high to reflect equilibrium precipitation with Nubian aquifer water or water of an exclusively Atlantic origin. Mg/Ca and Sr/Ca of the silts have a modest negative covariance with silt δ18O values, suggesting that the water may have experienced the shortest residence time in local aquifers when the water δ18O values were highest. Furthermore, intra-shell δ18O, Sr/Ca, and Ba/Ca analyses of the freshwater gastropod Melanoides tuberculata are consistent with a perennially fresh water source, suggesting that strong evaporative effects expected in a monsoonal climate did not occur, or that dry season spring flow was of sufficient magnitude to mute the effects of evaporation. The input of a second, isotopically heavier water source to aquifers, possibly Indian Ocean monsoonal rain, could explain the observed trends in δ18O and minor element ratios.

Coprolites of four distinct shapes, cylindrical, discoidal, beaded and irregular masses, are described from 11 horizons within Bed 16 of the Foulden sequence. These coprolites are composed of either phosphatic or claystone material, although they have not been analysed mineralogically or chemically. Their producers appear to have been fish, probably both nektonic predators and nekto-benthonic scavengers or detritus feeders.

Ostracods are poorly preserved and of two broad types, thick shelled paraparchitids including Shemonaella scotoburdigalensis and thin shelled podocopids, possibly species of Carbonita or Cavellina. This ostracod assemblage represents a conservative ‘carbonaceous fades’ fauna which occurs widely in plant-rich sediments in lower Carboniferous (Courceyan) sequences of northern England and southern Scotland. Other microfauna includes spirorbid worm tubes, fish scales, arthropod cuticle fragments, spat of myalinid bivalves, plant fragments and spores. No significant changes in the vertical distribution of the microfauna could be detected.

The microfauna indicates a general fresh to brackish water lacustrine or lagoonal environment possibly with access to quasi-marine conditions.