Characterization of Lower and Middle Pleistocene tephra beds in the southern plains of western Canada

Wellsch Valley tephra, near Swift Current, southwestern Saskatchewan, and Galt Island tephra, near Medicine Hat, southeastern Alberta, have been referenced in the literature since the 1970s, but little is available on their physical and chemical attributes – necessary information if they are to be recognized elsewhere. This study seeks to remedy this situation. Both have a calc-alkaline rhyolitic composition with hornblende, biotite, plagioclase, pyroxene, and Fe-Ti oxides being dominant. They have a similar composition but are not the same. Wellsch Valley tephra has a glass fission-track age of 0.75 ± 0.05 Ma, a reversed magnetic polarity, and was deposited at the close of the Matuyama Chron. Galt Island tephra has an age of 0.49 ± 0.05 Ma, a normal magnetic polarity, and was deposited during the early Brunhes Chron. Rich fossil vertebrate faunas occur in sediments close to them. Major- and trace-element concentrations in their glass shards indicate a source in the Cascade Range of the Pacific Northwest, USA, but differences in trace-element ratios suggest they are not consanguineous.

The late Matuyama glaciation in the southern European Alps

<p>The onset of Pleistocene glaciations in the European Alps represented a significant change in the palaeoenvironmental settings of this mountain range. The stratigraphy of the event was described in the subsoil of the Po Plain (Muttoni et al., 2003; Scardia et al., 2012) and is marked by a regional unconformity (namely “Red unconformity”, Muttoni et al., 2003) at 870 ka, in the final part of the Matuyama chron. Elsewhere, in the Alpine end-moraine systems the record of early stages of glaciations is scarce and cryptic. Spots of glacigenic deposits with reverse magnetic polarity were recognized only in the Ivrea (Carraro et al., 1991) and Garda (Cremaschi, 1987; Scardia et al., 2015) end-moraine systems, while deposits related to (peri)glacial environment were recorded along the Lombardian foothills (Scardia et al., 2010). The updated record of the Garda system shows the geometry of a late Matuyama glacier overrunning the piedmont plain with comparable size in respect to the LGM (Monegato et al., 2017). This indicates a fully glaciated Adige-Sarca catchment, one of the largest of the Alps, suggesting that the Alpine Ice Sheet reached one of its waxing climax during a late Matuyama cold stage (MIS20 or MIS22).</p><p> </p><p>References</p><p>Carraro et al. 1991, Boll. Museo Reg. Sc. Nat. Torino 9, 99-117.</p><p>Cremaschi 1987, Edizioni Unicopli, 306 pp.</p><p>Monegato et al. 2017, Scientific Reports 7, 2078.</p><p>Muttoni et al. 2003, Geology 31, 989-992.</p><p>Scardia et al. 2010, Quaternary Science Reviews 29, 832-846.</p><p>Scardia et al. 2012, Tectonics 31, TC6004.</p><p>Scardia et al. 2015, GSA Bulletin 127, 113-130.</p>

Neotectonics of the Pleistocene deposits in the northeast of Taman peninsula, the southern Asov sea region

Studies in paleomagnetism, structural geology, and paleontology (mammals, molluscs, palynology) in the coastal sections of the Taman Peninsula north-eastern part (2017–18) resulted in definition of three sedimentary members. The sandy and clayey lower member (I) formed at 2.1–1.7 Ma. It contains a normally magnetised zone within deposits of reversed polarity correlated to the Olduvai Subchron and the Matuyama Chron. The middle member (II) is composed of the basal pebbles overlain by sands. The reversely magnetised deposits hosting the Sinyaya Balka site, the type locality of the Tamanian faunal complex, is correlated to the basal bed of the middle member II. The overlying sands are normally magnetised (Jaramillo Subchron) in the lower part and show reverse polarity (late Matuyama Chron) in the upper part. The member II is dated in the range of 1.3–0.78 Ma. The silty upper member (III) represents Middle-Late Pleistocene. The dissimilar displacement degree of the members reflect developmental stages of the Quaternary deformation. The member I is characterised by dip angles up to 70° is fragmented by faults into blocks. The member II filled the relief of the eroded surface of the Member I and also displaced by faults. The faulting separated the bone-bearing body of the Taman faunal complex as a rock land-slide. The attitude of the member III outline an anticline with a gentle south-western and a steeper north-eastern limbs eroded by land-slides and marine abrasion. During its entire life the anticline was affected by mud volcanism. The anticline continues its development at the present stage.

Palaeoenvironmental and climatic inferences from the late early Pleistocene lacustrine deposits in the eastern Tiberino Basin (central Italy)

Within the Neogene-Quaternary evolution of the Mediterranean intermountain basins, the eastern Tiberino Basin provides new multifaceted chronological, biostratigraphic, palaeoecological, and palaeoenvironmental information, appreciably improving the knowledge of palaeoenvironmental and climate conditions during the middle-late Matuyama Chron (late early Pleistocene). Shallow to relatively deep lacustrine deposits and alluvial plain deposits, magnetostratigraphically calibrated, hold malacofaunas, ostracofaunas, and carpological remains, as well as a pollen record. Palaeocarpological remains widely originated from the local (azonal) vegetation of waterlogged environments. Nonetheless, some taxa show transitional morphology between possibly extinct Pliocene-Pleistocene forms and living taxa. The pollen record highlights a conifer-dominated forest phase, indicating a temperate-wet interglacial period, well aligned inside the schemes for the same latitudinal band. The abundance of tree taxa currently absent from the Italian peninsula points to pre-Jaramillo late early Pleistocene biostratigraphical characters, here compared to other sections from central Italy, and contributes to a better definition of modes and timing of their disappearance in southern Europe. Malacofaunas and ostracods, still with late early Pleistocene features, together with Charophyte, mark repeated fluctuations in energy, temperature, and chemical composition of water. The overall record identifies an incipient diachronous cooling trend, for the first time recognized in southern Europe.

Magnetostratigraphic dating of the Linyi Fauna and implications for sequencing the mammalian faunas on the Chinese Loess Plateau

The Chinese Loess Plateau (CLP) in North China is an important terrestrial archive that witnessed the environmental changes and mammal and early human evolution in Asia over the past 2.6 Ma. Establishing precise ages for the Pleistocene faunas on the CLP is critical for better understanding of these environmental, biological, and archaeological issues. Here we report a new magnetostratigraphic record that places age constraints on the Linyi Fauna on the southeastern CLP. Our investigated 170-m-thick Linyi section mainly consists of two portions: (1) an overlying eolian Quaternary loess-paleosol sequence and (2) underlying fluvial-lacustrine sand and silty clay. Paleomagnetic results suggest that the composite section records the Brunhes chron, Jaramillo and Olduvai subchrons, and successive reverse polarity portions of the intervening Matuyama chron. The Linyi Fauna is located between Jaramillo and Olduvai subchrons in the fluvial-lacustrine interval, with an estimated age of ~1.5–1.6 Ma. Combining previously dated faunas, we establish a Pleistocene magnetochronology spanning from 2.54 to 0.65 Ma for the faunas on the CLP.