Age of the Most Extensive Glaciation in the Alps

Previous research suggested that the Alpine glaciers of the Northern Swiss Foreland reached their maximum extensive position during the Middle Pleistocene. Relict tills and glaciofluvial deposits, attributed to the Most Extensive Glaciation (MEG), have been found only beyond the extents of the Last Glacial Maximum (LGM). Traditionally, these sediments have been correlated to the Riss glaciation sensu Penck and Brückner and have been morphostratigraphically classified as the Higher Terrace (HT) deposits. The age of the MEG glaciation was originally proposed to be intermediate to the Brunhes/Matuyama transition (780 ka) and the Marine Isotope Stage 6 (191 ka). In this study, we focused on the glacial deposits in Möhlin (Canton of Aargau, Switzerland), in order to constrain the age of the MEG. The sediments from these deposits were analyzed to determine the provenance and depositional environments. We applied isochron-burial dating, with cosmogenic 10Be and 26Al, to the till layer in the Bünten gravel pit near Möhlin. Our results indicate that a glacier of Alpine origin reached its most extensive position during the Middle Pleistocene (500 ± 100 ka). The age of the MEG thus appears to be synchronous with the most extensive glaciations in the northern hemisphere.

Late Acheulean Lithic Assemblages From Locality 010 at Gürgürbaba Hill (Eastern Anatolia)

The province of Van in north-eastern Turkey served as a land bridge between Africa and Eurasia during the Palaeolithic. The region is of particular relevance for understanding the movement of hominins between these continents. This study concerns the lithic remains from a locality at Gürgürbaba Hill, named Locality 010, north of the village of Ulupamir (Erciş district). Locality 010 was dated to 311±32 kya by terrestrial cosmogenic nuclides method, which coincides with Marine Isotope Stage 9 (MIS 9), a Middle Pleistocene interglacial period. The assemblage from this site is attributed to the Late Acheulean and resembles that of the southern Caucasus. This similarity indicates that the artefacts from Locality 010 were probably produced by late Lower Palaeolithic technology in a broad sense. These findings suggest local adaptations of late Middle Pleistocene hominins to high plateau environments.

Reconstruction of Polyhalite Ore-Formed Temperature from Late Middle Pleistocene Brine Temperature Research in Kunteyi Playa, Western China

Kunteyi Salt Lake (KSL), located in the northwest of the Qaidam Basin (QB), is rich in polyhalite resources. However, there is no relevant research on the ore-formed temperature of polyhalite in nature, such as KSL. The homogenization temperature ( T h ) of salt mineral inclusions can directly reveal the form temperature of minerals. In view of the poor diagenesis of polyhalite in KSL, almost no polyhalite crystals are formed. Therefore, the ore-formed temperature of polyhalite in KSL is revealed by using the T h of fluid inclusions in halite associated with polyhalite as a substitute index. A total of 472 T h data from 34 halite samples and 34 maximum homogenization temperature ( T hMAX ) data ranged from 17.1°C to 35.5°C, among which 24 data were concentrated at 17-23°C and the average value is 22.1°C. Brine temperature of other salt lakes in QB and paleoclimate characteristics of the study area were combined. It suggests that the temperature conditions of polyhalite mineralization in the study area are generally low. However, under the overall low-temperature background, polyhalite seems to be easily enriched at relatively high temperature; for example, the content of polyhalite is generally high in the first relatively dry and hot salt-forming period, and the brine temperature at the peak stage of polyhalite at 45 m is relatively high, which indicates that the high temperature conditions promote the formation of polyhalite in KSL. As far as the overall relationship between temperature and polyhalite is concerned, polyhalite is deposited at both low temperature and relatively high temperature, which verifies the previous understanding that polyhalite is a mineral with wide temperature phase, and also shows that temperature has a limited effect on polyhalite formation under natural conditions. In addition, combined with the chemical composition of halite fluid inclusions, it is found that the concentration of Mg2+ in nature has an influence on the temperature measurement process. According to the previous experimental research, speculate that the actual temperature of ancient brine and ore-formed temperature of polyhalite in KSL are lower than the measured T h . The confirmation of the influence of Mg2+ on temperature measurement is convenient for more accurate reconstruction of the metallogenic temperature of evaporite such as polyhalite. The research on the ore-formed temperature of KSL polyhalite enriches and perfects the polyhalite mineralization theory and provides theoretical basis for the basic and applied research of polyhalite.

Millennial-scale oscillations in the Kuroshio–Oyashio boundary during MIS 19 based on the radiolarian record from the Chiba composite section, central Japan

Marine isotope stage (MIS) 19 is considered to be the best orbital analog for the present interglacial. Consequently, clarifying the climatic features of this period can provide us with insights regarding a natural baseline for assessing future climate changes. A high-resolution radiolarian record from 800 to 750 ka (MIS 20 to MIS 18) was examined from the Chiba composite section (CbCS) of the Kokumoto Formation, including the Global Boundary Stratotype Section and Point for the lower–middle Pleistocene boundary on the Boso Peninsula on the Pacific side of central Japan. Millennial-scale oscillations in the Kuroshio warm and Oyashio cold currents were revealed by the Tr index, which is estimated using a simple equation based on radiolarian assemblages. The estimated Tr values ranged between 0.1 and 0.8 for MIS 18 through MIS 19, with minimum and maximum values corresponding to values observed off present day Aomori (41°N) and the Boso Peninsula (35°N), respectively. The observed patterns tended to be synchronous with the total radiolarian abundance associated with their production. Multiple maxima in radiolarian abundance occurred during periods of the Oyashio expanded mode before 785 ka and during periods of Kuroshio extension after 785 ka in MIS 19. Such increases in radiolarian abundance with the Kuroshio extension during MIS 19 are likely related to improvements in nutrient and photic environments with the development of a two-layer structure along the Kuroshio–Oyashio boundary zone. A similar pattern of millennial-scale climatic changes was also recognized in a precipitation record from the Sulmona Basin in central Italy, suggesting a close relationship with the CbCS record as a result of a large-scale climate system similar to the Arctic Oscillation in the northern hemisphere.

The Early Paleolithic Go Da Site and the Bifacial Lithic Industries of Southeast Asia

The lithic industry of the stratified site Go Da in Central Vietnam is described, and its place among the contemporaneous Early Paleolithic sites of East and Southeast Asia is determined. Results of a morphological technotypological analysis of the Go Da assemblage are provided. Go Da is attributed to the An Khe-type sites situated in the eponymous area of Vietnam. Cores and tools were made from pebbles, less often from fl akes. Primary reduction focused on simple pebble cores with natural striking-platforms, whereas radial cores were less common. Predom inant among the tools are picks, scrapers of various modifi cations, choppers, and chopping tools, as well as denticulate and notched tools; also, bifaces occur. These tools belong to a single homogeneous industry, showing common features in primary reduction, preparation, and design of key artifacts. On the basis of analysis of the stratigraphic sequence of Go Da and the absolute date of 806 ± 22 ka BP, generated by the potassium-argon analysis of tektites, it is proposed that the site is older than other dated locations with the An Khe industry. Apparently, it resulted from a convergent evolution of the pebble-fl ake industry introduced by the fi rst wave of Homo erectus from Africa. Go Da and other An Khe sites likely belong to a vast habitation zone of Southeast Asian hominins with technologically and typologically similar industries dating to the boundary between the Lower and the Middle Pleistocene.