Journal of Quaternary Science最新文献

The hypersaline Urmia Lake in NW Iran offers unique sedimentary environments sensitive to climate and environmental shifts, fostering coated grain formation and serving as a vital indicator of paleoenvironmental conditions. This study characterizes coated grains within a 25-m sediment core dating back to ~50 cal ka bp, assessing their significance through morphology, internal structures, mineralogy, and geochemistry. Coated grains in Urmia Lake exhibit concentric laminations, primarily calcite and aragonite, revealing alternating light carbonate-rich and dark organic-rich laminations. These reflect seasonal and long-term variations in water chemistry and biogenic production. Dry season algal blooms contribute to lamination, highlighting the interplay between seasonal climate fluctuations and the consequent lake water enrichment in calcium, carbonate, and bicarbonate ions. The diversity and abundance of coated grains indicate three main lake level fluctuation stages in the last ~50 cal ka: a lowering stage with dominant coated grains, a low lake level with dominant terrigenous fragments and minerals, and a high lake level with prominent Artemia urmiana fecal pellets. The role of the brine shrimp A. urmiana in coated grain formation involves absorbing calcium, carbonate, and bicarbonate ions and inhibiting coated grain formation during high lake levels while providing nuclei during lake lowering. An in-depth investigation of coated grains provides a chemical and biological formation framework, highlighting three main episodes in the lake's history.

The Sakarya, one of the longest rivers in northwest Anatolia, has significant geomorphological units along its course including terrace systems that have potential to reveal the tectonic and geomorphological evolution of the region. The aim of this research was to identify the processes that have influenced the formation of terrace systems based on regional and local tectonic activities during the Late Quaternary and effects of global climatic changes on levels of the Black Sea. In particular along the İnhisar–Osmaneli section of the Sakarya River, the terrace systems, which are determined at four different levels, are crucial in terms of illuminating the geomorphological development of the region during the Late Quaternary. Our optically stimulated luminescence results revealed three different ages of deposition: 158.03 ± 12.93, 150.97 ± 8.49 and 55.07 ± 4.57 ka (Middle–Late Pleistocene). This permitted calculation of a mean regional uplift rate of 0.18 ± 0.03 mm a^–1 since the Middle–Late Pleistocene. The younger terrace remnants correspond to Late Pleistocene Marine Isotope Stage (MIS) 3c (interstadial) and the older ones to Late Middle Pleistocene MIS 6b (interstadial). This implies that the Sakarya River accumulated floodplain sediments, now terraces, during relatively warm and humid periods. On the other hand, in cold and/or cold–warm transition periods, it created terraces by incision into the river bed. This interpretation implies that fluvial incision in the region was a response to regional uplift that has been continuing for at least the last 158 ka.

This paper proposes a new approach to quantitative geomorphology and paleopedology in the mid-Rhône valley (MRV) based on a compilation of geomorphological metadata from 25 tributaries of the Rhône river and subordinate floodbasins, including 51 geomorphological and paleopedological sites. This study compares two types of hydrogeomorphological data formalization: a temporal similarities analysis between paleosols and fluvial aggradation of sub-basins, and a quantitative analysis by summed probability distributions comparing floodplain stability and activity phases in cumulative density functions of categorized ¹⁴C and chronocultural dates. Alluvial chronologies at centennial to millennial time scales, coinciding with a modification in sedimentation rate, or river style, demonstrate temporal and spatial patterning of MRV alluviation, pedogenesis and erosion across the western Prealpine region, with detection of 24 main Holocene alternative periods (activity versus stability). To explore possible large-scale hydroclimatic teleconnections, the Holocene MRV results are aligned, and correlations are made, with those of a range of paleohydrological proxy studies from all Rhône drainage basins, Western Europe and the Mediterranean. The MRV rivers respond to the majority of Holocene rapid climatic changes and from 4000/3000 cal a bp to an accelerated sediment delivery and torrentiality from slopes and headwaters, which results in the development of sedimentary cascades from upstream to downstream in the Rhône valley to the delta (the main drivers are discussed in detail in in a companion paper to follow).

New material of Lutra simplicidens, a key species for understanding the evolution of Eurasian Lutrinae, is described from the English site of Corton (0.7‒0.6 Ma) and the Polish site of Żabia Cave (1.7‒1.5 Ma). Both records are represented by incomplete mandibles with partially preserved dentition. The record from Żabia Cave documents the presence of an older and more carnivorous Lutra simplicidens tamanensis. A less carnivorous Lutra simplicidens simplicidens was found in Corton. Both findings contribute valuable data on the evolutionary history of the species.

The Yabrai range-front fault (YRF) is a large-scale fault within the Alashan Block, located northeast of the Tibetan Plateau, which has undergone several surface rupture events on the southwestern and middle segments since the late Quaternary. As no relevant research has been conducted on the northeastern segment, paleoseismic data for this area are lacking, which restricts our overall understanding of the spatiotemporal and intensity distribution of strong earthquakes on the YRF. To address this problem, we conducted investigations based on trench wall interpretation and stratigraphic optically stimulated luminescence ages. Four paleoearthquakes were identified in the middle of the northeastern segment, and occurred after 11.6 ± 0.7 ka and between 11.6 ± 0.7 to 6.9 ± 0.5, 6.9 ± 0.5 to 4.8 ± 0.6 and 4.8 ± 0.6 to 3.9 ± 0.7 ka, respectively. Three paleoearthquake events, one of which occurred at around 23.6 ± 1.6 ka, were identified at the northeastern end of the fault. According to the spatiotemporal distribution of the ruptured events on the YRF, the middle segment may be a long seismic gap (~8 ka), and combined with the status of tectonic stress concentration, this segment can be regarded as a zone of high seismic probability with the ability to produce a magnitude 7.2 earthquake. Furthermore, from the late Pleistocene to early Holocene, cascading ruptures may have occurred on the middle and northeastern segments of the YRF, with magnitudes approaching 7.3. In terms of tectonic relationships, we suggest that the YRF and the Langshan piedmont fault are two independent faults even though they are connected.

We describe and analyze the glacial geomorphology and new ¹⁰Be cosmogenic surface exposure ages from moraines deposited before Marine Isotope Stage (MIS) 2 around Nevado de Chañi (24°4′ S, 65°45′ W), a north–south-trending massif located in the arid subtropical mountains of northwestern Argentina. We combine these data with previously published ages in order to establish a glacier chronology around the massif and the central Andes. The results show at least three phases of glacier expansions occurred before the global Last Glacial Maximum, (i) during MIS 6, (ii) close to the transition from MIS 4 to MIS 3, and (iii) during mid-late MIS 3. Based on a comparison of the timing of glacier advances with other glacial and paleoclimatic proxies elsewhere, we infer that glaciers grew in this arid region of the subtropical Andes during periods of reduced temperatures and wetter conditions, ultimately due to intensification of the South American Summer Monsoon. In contrast, during MIS 5 no glacial activity was recorded around the massif, and we infer that even if wetter conditions prevailed in the region the temperature was not sufficiently low to support glaciations.