Late Pleistocene Time Research Articles

From wolf to dog: Late Pleistocene ecological dynamics, altered trophic strategies, and shifting human perceptions

The immediate ancestors of modern domestic dogs emerged from wild wolves in latest Pleistocene times. In taking up life with people, they represent a lineage of wolves that escaped the extinction that struck a variety of animals at that time. Unlike wild wolves, animals that became well known apex predators of recent times, wolves that became dogs initially joined hunting-gathering people, many of whom functioned as apex predators. As such, those original dogs were equipped with meaningful behavioral compatibility with people, and some of them surely assisted hunting-gathering peoples with important hunting activities. Initial social compatibility between people and dogs was further refined as the Pleistocene gave way to the Holocene and the new dog population grew and expanded. Where people later developed agricultural economies, however, dogs transitioned with them as apex consumers, a fundamental change in trophic strategy. But in embarking on that new strategy dogs tended to become a less conspicuous part of people’s lives. Noteworthy exceptions to that generalization underscore the diversity of roles that dogs have played, and continue to play, in the human psyche.

Diet and habitat of mesomammals and megamammals from Cedral, San Luis Potosí, México

AbstractUsing carbon and oxygen isotopic relationships from dental enamel, diet and habitat were inferred for both mesomammals and megamammals that lived in Cedral (San Luis Potosi, north-central México) during Late Pleistocene time. δ13C and δ18O values show that bison, some horses and mammoth were eating C4 plants and lived in open areas, while tapir, camel and some llamas ate C3 plants and inhabited closed areas. All other studied herbivores (pronghorn, glyptodont, mylodont ground sloth, javelina, mastodon, and other llamas, horses and mammoth) had a C3/C4 mixed diet, living in areas with some percentage of tree coverage. On the other hand, American lion and dire wolf ate either C4 or mixed-diet herbivores, and short-faced bear ate C3 herbivores. At Cedral, more humid conditions existed than presently, allowing the presence of a forested area near the grassland.

Do magnetic fabrics of marine deposits preserve orbital forcing? A test case in the Southern Ocean, Antarctic Peninsula

The anisotropy of magnetic susceptibility (AMS), or magnetic fabric, of marine sediments is related to depositional current strength; higher AMS values indicate stronger currents. We have collected a 3.1 m.y. record of AMS data from the abyssal silts of Drift 4 (Ocean Drilling Program Site 1101) on the Pacific margin of the Antarctic Peninsula. Spectral analyses of these data show strong, uniform, 100 k.y. and 400 k.y. power in-phase with minima in Earth’s eccentricity throughout the long record. However, significant variability related to the 40 k.y. period of obliquity is absent. The unchanging strong 100 k.y. power and the apparent absence of 40 k.y. variability in the AMS record are in contrast to the behavior of most other paleoclimatic proxies for late Pliocene and Pleistocene time.

New exploration discoveries in a mature basin: offshore Denmark

Abstract In 2011, two discoveries were drilled by PA Resources in the Danish sector. The Broder Tuck 2/2A wells were drilled on a thrusted anticlinal structure, downdip of the apparently small U-1X gas discovery. The wells found an excellent quality gas reservoir within an interpreted Callovian lowstand incised valley containing braided fluvial and marginal-marine sandstones. A top and base seal are provided by mudstones of the over- and underlying transgressive systems tracts respectively. The development of a base seal is key to the presence of a potentially commercial resource downdip of a relatively unpromising old well. The Lille John 1/1B wells were then drilled on a salt diapir on which 1980s wells had encountered shallow oil shows. Lille John 1 found slightly biodegraded 34° API oil in Miocene sandstones at the uncommonly shallow depth of −910 m true vertical depth subsea (TVDSS). The reservoir is full to spill, whilst the trap developed intermittently through latest Miocene–Late Pleistocene times. It is interpreted that a deeper Chalk accumulation temporarily lost seal integrity owing to glacially induced stress or overpressure triggering top-seal failure or fault reactivation during and after latest Pleistocene diapir inflation. The wider hydrocarbon exploration implications of glaciation on stress, pore pressure and trap integrity appear to be underappreciated.

Kinematics of late Quaternary slip along the Yabrai fault: Implications for Cenozoic tectonics across the Gobi Alashan block, China

The Yabrai range-front fault accommodates deformation within the middle Gobi Alashan block between the Tibetan Plateau and the Ordos block. As such, it provides the opportunity to examine the transition between contractional deformation associated with the growth of the Tibetan Plateau and extensional deformation across North China. Geomorphic mapping of the active fault trace and trench investigations reveal that the Yabrai range-front fault is composed of three segments of varying fault strike, but for which the sense of motion, scarp height, and slip history appear to be kinematically compatible along the fault. Displaced Holocene and late Pleistocene alluvial deposits indicate that the southwestern segment is characterized by oblique-normal displacement with a minor sinistral component, whereas the middle segment appears to exhibit nearly dip-slip normal displacement. In contrast, slip along the northeastern segment appears to be primarily sinistral strike-slip with a minor reverse component. Geomorphically fresh fault scarps are developed within late Pleistocene–Holocene alluvial fans and terraces along the southwestern and northeastern segments, whereas the middle segment of the fault defines the bedrock-alluvial contact along the range front. The 10Be exposure ages of displaced alluvial fans along the southwestern segment yield a throw rate of ∼0.1 mm/yr over late Pleistocene time. Lateral slip rates along the northeastern fault segment range between 0.23 ± 0.02 and 0.78 ± 0.12 mm/yr. Regionally, the orientation and sense of motion along the Yabrai range-front fault are consistent with NE-SW shortening, and we suggest that recent activity along this fault system reflects incipient deformation of the foreland at the northeastern margin of the Tibetan Plateau.

Late Pleistocene Tendürek Volcano (Eastern Anatolia, Turkey): I. Geochronology and petrographic characteristics of igneous rocks

The series of two papers presents a comprehensive isotope-geochronological and petrological-geochemical study of the Late Quaternary Tendurek Volcano (Eastern Turkey), one of the greatest volcanoes within the Caucasian—Eastern Anatolian segment of the Alpine foldbelt. The first article discusses the results of chronostratigraphic reconstruction and provides the main petrographic characteristics of the Tendurek’s igneous rocks. The K-Ar dating results show that the magmatic activity of the Tendurek Volcano developed in the Late Pleistocene time, over the period of the last 250 thousand years. Five discrete phases (I—250–200 ka, II—200–150 ka, III—150–100 ka, IV—100–70 ka, and V—<50 ka) of the youngest magmatism were identified in this study. The first two phases were represented by the fissure eruptions of alkaline basic lavas and subsequent formation of vast lava plateaus, the Caldiran and Dogubeyazit plains. In the following phases, the intermediate and moderately-acid volcanic rocks of mildly-alkaline or alkaline series started to dominate among the eruption products. According to their petrographic characteristics, the rocks of Tendurek Volcano are assigned to the alkaline association with Na-specifics (hawaiites-mugearites-benmoreites). The available geological, isotope-geochronological, and geomorphological data suggest that the Tendurek Volcano is potentially active. Nowadays, Tendurek reaches the caldera stage of its development.

Middle to Late Pleistocene dunefields in rocky coast settings at Cala Xuclar (Eivissa, Western Mediterranean): Recognition, architecture and luminescence chronology

This study focuses on cliff-front anchored and sand-ramp aeolian dune accumulations in Cala Xuclar, Eivissa (Ibiza), Western Mediterranean, during different sea level falling stages from Middle to Late Pleistocene times. Stratigraphic mapping, conventional lithostratigraphic logging and OSL datings are used to reconstruct dune formation and evolution. Facies analyses result in the identification of six sedimentary units, three of which correspond to dune deposits formed at MIS 6 (145 ka), MIS 5d-c (∼100 ka) and MIS 4 (77–73 ka) respectively. Additionally there is a beach deposit at (∼2 m above present msl, which resembles the MIS 5a. This study concludes that each dune system corresponds to a relatively low sea-level stand that exposed enormous amounts of marine carbonate sands that was transported inland by migrating dunes under strong north–westerly winds. Therefore, sea-level fall and the related sediment supply owe likely to be key factors in the formation of these aeolianites systems.

Geophysical characterization of buried active faults: the Concud Fault (Iberian Chain, NE Spain)

The Concud Fault is a ~14-km-long active fault that extends close to Teruel, a city with about 35,000 inhabitants in the Iberian Range (NE Spain). It shows evidence of recurrent activity during Late Pleistocene time, posing a significant seismic hazard in an area of moderate-to-low tectonic rates. A geophysical survey was carried out along the mapped trace of the southern branch of the Concud Fault to evaluate the geophysical signature from the fault and the location of paleoseismic trenches. The survey identified a lineation of inverse magnetic dipoles at residual and vertical magnetic gradient, a local increase in apparent conductivity, and interruptions of the underground sediment structure along GPR profiles. The origin of these anomalies is due to lateral contrast between both fault blocks and the geophysical signature of Quaternary materials located above and directly south of the fault. The spatial distribution of anomalies was successfully used to locate suitable trench sites and to map non-exposed segments of the fault. The geophysical anomalies are related to the sedimentological characteristics and permeability differences of the deposits and to deformation related to fault activity. The results illustrate the usefulness of geophysics to detect and map non-exposed faults in areas of moderate-to-low tectonic activity where faults are often covered by recent pediments that obscure geological evidence of the most recent earthquakes. The results also highlight the importance of applying multiple geophysical techniques in defining the location of buried faults.

Rates and kinematics of active shortening along the eastern Qilian Shan, China, inferred from deformed fluvial terraces

AbstractIn the eastern Qilian Shan, a flight of fluvial terraces developed along the Jinta River valley are deformed across the Nanying anticline. Four individual fluvial terraces are preserved at different elevations above the river, and higher terrace treads are draped by systematically thicker aeolian loess. Optically stimulated luminescence dating of deposits at the base of the loess provides constraints on the timing of surface abandonment; terraces were abandoned at 69 ± 4 ka B.P. (T4), 57 ± 4 ka B.P. (T3), and between 34 ± 3 ka B.P. (T2), respectively. Differential GPS measurement of the terrace profile across the anticline allows reconstruction of subsurface fault geometry; we model terrace deformation above a listric thrust fault with a tip line at 2.2 ± 0.1 km depth and whose dip shallows systematically to 23 ± 3° at depth of 5.8 ± 1.1 km. Combining terrace ages with this model of fault geometry, we estimate a shortening rate of 0.8 ± 0.2 mm/a across the Nanying fold and a shortening rate of ~0.1 mm/a across the mountain front fault since ~70 ka B.P. This rate suggests that the frontal fault system along the eastern Qilian Shan accomplishes crustal shortening at rates of approximately 0.9 ± 0.3 mm/a during late Pleistocene time.

Late Quaternary benthic foraminifera and the Orinoco Plume

Abstract The bathyal benthic foraminiferal palaeoecology east of Trinidad is currently unknown. The area is oceanographically complex, comprising a pro-delta deep-sea fan building across a transpressional plate boundary. Outflow from the Orinoco River forms a high-productivity surface plume that abuts low-productivity water of the tropical western Atlantic Ocean across a laterally extensive but sharp front. The plume's areal extent differs between the rainy and dry seasons, which are governed by the position of the inter-tropical convergence zone (ITCZ). Upper Quaternary benthic foraminifera are examined in two ~ 4 m-long piston cores, taken near the eastern edge of the plume. CHIRP profiles show that core BGT086 (water depth 626 m) comprised in situ material throughout, while the lower part of core BGT096 (water depth 700 m) consisted of slumped material. Benthic foraminiferal assemblages in BGT086 were examined quantitatively, while those in BGT096 were examined qualitatively only for comparison. Core BGT086 shows a transition from a low-diversity, Cibicidoides pachyderma-dominated community with subdominant Cassidulina curvata to a later high-diversity, low-dominance Bulimina alazanensis–Osangularielloides rugosa–Epistominella exigua community. The former is indicative of low-productivity, and the latter of high-productivity, surface water. The restriction of E. exigua to the core's upper part may reflect a change from an aseasonal to a seasonal organic flux. The faunal change was detected by both SHE and cluster analyses and an assemblage turnover index (ATI). It may be related to either (a) expansion of the Orinoco plume due to northward migration of the ITCZ approximately 600 yr after the end of the Younger Dryas, (b) eastward progradation of the Orinoco Delta, which would in turn push the front of the Orinoco plume eastward, or (c) both. No other boundary detected was common to all three procedures. A boundary between 124 and 130 cm below the seafloor detected by SHE analysis might equate to the 8000–7500 yr BP meltwater pulse 1C. While some specialist species were restricted to the C. pachyderma or the B. alazanensis–O. rugosa–E. exigua communities, the percentage abundance of some others, concluded to be relative generalists (e.g., Bulimina aculeata and Sphaeroidina bulloides), varied little through the core. The undisturbed section of core BGT096 showed the same general faunal succession as core BGT086. The slumped material in this core was rich in Eponides regularis, which was rare elsewhere. This species shows that the allochthonous sediment was derived from the outer shelf and upper slope (100–400 m water depth) during Late Pleistocene time.

On the timing and forcing mechanisms of late Pleistocene glacial terminations: Insights from a new high-resolution benthic stable oxygen isotope record of the eastern Mediterranean

Benthic oxygen isotope records of deep marine sedimentary archives have yielded a wealth of information regarding ice sheet dynamics and climate change during the Pleistocene. However, since they often lack independent age control, these records are generally bound by a fixed phase relationship between orbital forcing and the climate response, e.g. ice volume changes. We present the first long (∼1.2 Ma) benthic oxygen isotope record from the eastern Mediterranean, based on ODP Sites 967 and 968, which clearly reflects the behavior of global climate on a glacial–interglacial scale throughout the late Pleistocene time period. The age model for our record is based on tuning the elemental ratio of titanium versus aluminum (Ti/Al) against insolation. The Ti/Al record is dominated by the precession-related changes in northern African climate, i.e. monsoonal forcing, and hence largely independent of glacial–interglacial variability. We found the largest offset between our chronology and that of the widely applied, open ocean stacked record LR04 (Lisiecki and Raymo, 2005) for TVII (∼624 ka), which occurred ∼9 kyr earlier according to our estimates, though in agreement with the AICC2012 δDice chronology of EPICA Dome C (Bazin et al., 2013). Spectral cross-correlation analysis between our benthic δ18O record and 65°N summer insolation reveals significant amounts of power in the obliquity and precession range, with an average lag of 5.5 ± 0.8 kyr for obliquity, and 6.0 ± 1.0 kyr for precession. In addition, our results show that the obliquity-related time lag was smaller (3.0 ± 3.3 kyr) prior to ∼900 ka than after (5.7 ± 1.1 kyr), suggesting that on average the glacial response time to obliquity forcing increased during the mid-Pleistocene transition, much later than assumed by Lisiecki and Raymo (2005). Finally, we found that almost all glacial terminations have a consistent phase relationship of ∼45 ± 45° with respect to the precession and obliquity-driven increases in 65°N summer insolation, consistent with the general consensus that both obliquity and precession are important for deglaciation during the Late Pleistocene. Exceptions are glacial terminations TIIIb, T36 and potentially T32 (and TVII T24 and T34), which show this consistent phase relationship only with precession (only with obliquity). Our findings point towards an early (>1200 ka) onset of the Mid Pleistocene Transition. Vice versa, the timing of TVII, which can only be explained as a response to obliquity forcing, indicates that the transition lasted until at least after MIS 15.

Late Quaternary history of the Vakinankaratra volcanic field (central Madagascar): insights from luminescence dating of phreatomagmatic eruption deposits

The Quaternary Vakinankaratra volcanic field in the central Madagascar highlands consists of scoria cones, lava flows, tuff rings, and maars. These volcanic landforms are the result of processes triggered by intracontinental rifting and overlie Precambrian basement or Neogene volcanic rocks. Infrared-stimulated luminescence (IRSL) dating was applied to 13 samples taken from phreatomagmatic eruption deposits in the Antsirabe–Betafo region with the aim of constraining the chronology of the volcanic activity. Establishing such a chronology is important for evaluating volcanic hazards in this densely populated area. Stratigraphic correlations of eruption deposits and IRSL ages suggest at least five phreatomagmatic eruption events in Late Pleistocene times. In the Lake Andraikiba region, two such eruption layers can be clearly distinguished. The older one yields ages between 109 ± 15 and 90 ± 11 ka and is possibly related to an eruption at the Amboniloha volcanic complex to the north. The younger one gives ages between 58 ± 4 and 47 ± 7 ka and is clearly related to the phreatomagmatic eruption that formed Lake Andraikiba. IRSL ages of a similar eruption deposit directly overlying basement laterite in the vicinity of the Fizinana and Ampasamihaiky volcanic complexes yield coherent ages of 68 ± 7 and 65 ± 8 ka. These ages provide the upper age limit for the subsequently developed Iavoko, Antsifotra, and Fizinana scoria cones and their associated lava flows. Two phreatomagmatic deposits, identified near Lake Tritrivakely, yield the youngest IRSL ages in the region, with respective ages of 32 ± 3 and 19 ± 2 ka. The reported K-feldspar IRSL ages are the first recorded numerical ages of phreatomagmatic eruption deposits in Madagascar, and our results confirm the huge potential of this dating approach for reconstructing the volcanic activity of Late Pleistocene to Holocene volcanic provinces.

Tayassu pecari (Link, 1795) (Mammalia, Cetartiodactyla): comments on its South American fossil record, taxonomy and paleobiogeography

Tayassu pecari is widely distributed across the Neotropical region, from northern Argentina to south-eastern Mexico. However, its fossil record is scarce; it is recorded since the middle Pleistocene to Holocene in Argentina, Brazil and Uruguay. This paper aims to: (1) update the systematic synonymy of this species; (2) review and update its geographic chronologic distribution and provide a new Lujanian record of Tayassu pecari in Buenos Aires Province and (3) discuss the paleoenvironmental and paleobiogeographical implications of this record. Considering the quantitative analysis performed, the fossil here recorded clearly integrates the group of Tayassu pecari. This specimen corresponds to the first record of Tayassu pecari in the central-northern region of the Buenos Aires Province. During Late Pleistocene, Tayassu pecari was distributed southern to its recent range, probably evidencing different paleoenvironment conditions. This species is the better adapted peccary to tropical and subtropical rainforests, but may also be present in arid environments. Consequently, Tayassu by itself is insufficient to infer the prevailing environmental conditions. However, according to the fauna associated with the specimen described here, it is possible to infer an open or semi-open and arid or semi-arid environment for the central-northern Buenos Aires region by Late Pleistocene times.

West Timor: a key for the eastern Indonesian geodynamic evolution

Abstract Timor Island was at time considered as an example of “accretionary prism” linked to the collision between the Australian block and the Banda arc. However, its geological evolution is more complex. Five main superimposed structural units are distinguished in West Timor. The today structure is the result of three main tectonic events that occurred during the Late Oligocene, Late Early Pliocene and Late Pliocene-Early Pleistocene times, respectively. Our field investigations in the 1990 to 2000 decade completed with geochemical analyses and K-Ar datings (Jurassic and Miocene ages) of magmatism allow to precise the geodynamic evolution of Timor that can be summarized as follows: a first block was detached from Gondwana (unit 2) and drifted to the Asiatic margin until the Late Oligocene when it collided with the Asiatic active margin (unit 3). Then, the new block formed by both 2 and 3 units drifted to the south during the Miocene and the Early Pliocene until it collided with the Australian margin (ASM), by the Late Early Pliocene. Then, the Australian and Timor blocks moved together towards the North-North East during the Late Pliocene until they collided with the Banda fore-arc (unit 4). Later on (Pleistocene), Timor island was capped by the “autochthon” (unit 5) and then on (Quaternary?) by the Banda volcanic arc northward thrusted over the South Banda basin. Taking in consideration its close relationships with both the Australian plate and the Eurasian one. Timor may be considered as a key area for building this geodynamical scenario of Indonesia.

Geomorphology of the Tsetseg Nuur basin, Mongolian Altai – lake development, fluvial sedimentation and aeolian transport in a semi-arid environment

The landform ensemble of the Tsetseg Nuur Basin in Western Mongolia provides an archive for periods of different geomorphologic processes induced by changing climate conditions during the Holocene and late Pleistocene times. The geomorphologic map of Tsetseg Nuur basin in the Mongolian Altai illustrates the spatial relation and interaction between different types of sedimentation in semi-arid regions of Central Asia. The map is an instrument to visualize the geomorphologic settings, providing valuable information to distinguish periods of geomorphologic processes and to analyze the landscape evolution. This enables the creation of a relative morphostratigraphy of periods with different hydrological environments, mainly marked by the stages of lake level evolution in an interior drainage basin. The relative chronology calculated from the map receives an absolute chronostratigraphy through radiometric dating from selected sections investigated during field-work.

Mud volcano origin of the Mottled Zone, South Levant

The Mottled Zone (MZ) or Hatrurim Formation, which occurs near the Levantine Transform in the South Levant, has been studied during the last 150 years but its origin remains debatable. Mottled Zone Complex/Complexes (MZC/MZCs) consist of brecciated carbonate and low-temperature calcium-hydrosilicate rocks, which include unusual high- and ultra-high-temperature low-pressure (HT-LP) metamorphic mineral assemblages. The MZ has been regarded as a product of combustion of bituminous chalks of the Ghareb Fm. of Cretaceous (Maastrichtian) age. In this paper we present detailed geographic, geomorphologic, structural and geological data from the MZCs of the South Levant, which show that the MZCs cannot be stratigraphically correlated with the Ghareb Fm., because MZC late Oligocene–late Pleistocene deposits occur within or unconformably, i.e., with stratigraphic hiatus, overlap both the late Cretaceous and, in places, Neogene stratigraphic units. We propose an alternative model for the formation of MZCs by tectonically induced mud volcanism during late Oligocene–late Pleistocene time. This model explains (i) the presence of dikes and tube-like bodies, which consist of brecciated exotic clastic material derived from stratigraphically and hypsometrically lower horizons; (ii) mineral assemblages of sanidinite facies metamorphism; (iii) multi-stage character of HT-LP pyrometamorphism; and (iv) multi-stage low-temperature hydrothermal alteration. High temperatures (up to 1500 °C) mineral assemblages resulted from combustion of hydrocarbon gases of mud volcanoes. Mud volcanism was spatially and structurally related to neotectonic folds and deformation zones formed in response to opening of the Red Sea rift and propagation of the Levantine Transform Fault. Our model may significantly change the prospects for oil-and-gas deposits in the region.

Where is the line? Phylogeography and secondary contact of western Palearctic coal tits (Periparus ater: Aves, Passeriformes, Paridae)

In this study, a phylogeographic scenario of the coal tit (Periparus ater) was reconstructed based on a fragment of the mitochondrial control region, and within- and between-population genetic diversity was analysed with a focus on the western Palearctic breeding range. We inferred a first pan-European delimitation of a postulated secondary contact zone among coal tits from the north-eastern Palearctic ater subspecies group and those from the south-western Palearctic abietum group. Generally, between-population differentiation was greatest in the Mediterranean range, which was explained by a greater separation in multiple Pleistocene refuge areas compared to the lower differentiation across the north-eastern Palearctic range. Genetic diversity indices were lowest on Mediterranean island populations as compared to continental populations. Pairwise ΦST values were highest among island populations and the Eurasian continent on the one hand and among the continental north-eastern ater and south-western abietum group on the other. Local co-occurrence of ater and abietum haplotypes was found all across Germany and in one Greek population. Molecular dating suggested that these two major subspecies groups separated from each other and from two further North African and Middle Eastern coal tit lineages during the early to mid-Pliocene. Successively, the Mediterranean region remained a centre of mainly insular diversification until late Pleistocene times including a long period of steady population growth. At the same time, at least four distinct genetic lineages emerged in eastern Eurasia, the nominate ater subspecies group being one of them. Finally, during the Holocene extant wide-range secondary contact in Europe was established via rapid westward range expansion from an East Asian refuge and via northeastward expansion from Mediterranean refuges.

Hydroxy-interlayered vermiculite genesis in Jiujiang late-Pleistocene red earth sediments and significance to climate

To understand the paleoclimatic significance of the red earth sediments in Jiujiang, southern China, hydroxy-interlayered vermiculite (HIV) in the deposits was investigated using X-ray diffraction (XRD), chemical extraction, and high resolution transmission electron microscopy (HRTEM). The XRD results indicated that the clay mineral assemblages of the sediments are mainly illite, kaolinite, HIV, vermiculite, with minor illite-HIV mixed-layer clays. The 1.41-nm reflection did not expand after Mg saturation and glycerol solvation, but it shifted to 1.38nm and 1.20nm when the samples were heated to 350°C and 550°C, respectively. The 1.41-nm spacing showed partial collapse after K+ saturation at 80°C in association with the reinforcement of the 1.0nm reflection. Collapse of the HIV (001) spacing was related to the release of Al, Mg, and Ca from the interlayer after KCl extraction. The Al was probably present as hydroxy-Al in HIV interlayers before being released. The HRTEM image revealed 1.4-nm lattice fringes interstratified with illite 1.0nm fringes and two illite lattice fringes merged into one HIV fringe. This suggests that the HIV clays in Jiujiang soils resulted from illite weathering. The shift of a small X-ray diffraction reflection between 1.0 and 1.4nm for an air-dried and glycerol-solvated sample to 0.997nm after heating at 550°C indicated the presence of an irregularly interstratified illite–HIV mineral. The common occurrence of HIV minerals in the Jiujiang red earth sediments suggests a climate with frequent wet and dry cycles prevailed during late-Pleistocene time.

Evolution of an Alpine over-deepened valley (Upper Enns Valley, Austria) within the context of geomorphic and tectonic expressions

In the study area, the Eastern Alps have been under surface uplift since Early Miocene times. Furthermore, Quaternary processes as uplift and cyclic glaciations likely interfere with neotectonic activity as the Upper Enns Valley is bounded to the Salzach-Enns strikeslip fault. The interplay between differential uplift and denudation and glacial carving results in a present-day diversity of morphology. An asymmetric drainage pattern with short northern tributaries to the Upper Enns Valley and long southern ones suggests N-ward tilting of the entire region. Provenance analysis of the Upper Pleistocene Ramsau Conglomerate on the northern valley slope indicates primarily a derivation from the basement terrain of the Niedere Tauern located to the south of the Enns Valley. The transport from the southern side of the valley and the presence of a terrace at 1,100 m allows the assumption that the Upper Enns Valley was filled up to that elevation during Late Pleistocene times. The suggested continuity of the southern planation surfaces and the top of the Ramsau Conglomerate (ca. 1,100 m a.s. l.) is interpreted to represent a relic former valley bottom. An intercalated coal seam in the conglomerate dated back to 53.3 kyr. by 14C method (uncalibrated) is a crucial element to reconstruct the evolution of the valley. Geomorphological and sedimentological investigations coupled with a fluvial landscape along a major strike-slip fault allowed developing the morphogenetic history of the Upper Enns Valley (Austria).

Glacial, fluvial and volcanic landscape evolution in the Laguna Potrok Aike maar area, Southern Patagonia, Argentina

We describe the Pleistocene evolution of the landscape in the Laguna Potrok Aike area in southern Patagonia, Argentina, based on a geomorphological survey. Basaltic eruptions generated tablelands and scoria cones between the Late Miocene and Middle Pleistocene, and phreatomagmatic eruptions produced maars during Middle and Late Pleistocene time. The first glaciations during the Early Pleistocene generated a gently undulating to flat landscape that was affected by cryogenic processes; they are documented but not dated. Outwash surfaces indicate that the Greatest Patagonian Glaciation was multi-phased. The eruption that produced Potrok Aike maar truncated terrace levels dating to a Middle Pleistocene glaciation. The abundance of maars dating to this time may be linked to large amounts of water associated with meltwater streams and permafrost. The landscape in the Potrok Aike area has changed little since the Middle Pleistocene and only minor modifications of landforms have occurred due to cryogenesis, moderate fluvial incision, mass wasting and eolian activity.