Quaternary Glacial Events Research Articles

New evidence about the Palaeolithic peopling of the southern margin of the western Alps. The Colline novaresi area

The Colline novaresi area is located in the north-eastern part of Piedmont. The hills are formed by moraine deposits and fluvio-glacial lithologies originating from Quaternary glacial events, which in turn were affected by a process of fluvial terraces. This area has been known for decades for the presence of archaeological sites, among which the most studied belong to a time span ranging from the Copper Age to the Iron Age. In the 1980′s, a Mesolithic lithic assemblage (Castelnovian) was found during investigation activities and was object of a techno-typological analysis.The present work, within the limits imposed by the non-systematic recovery of surface collections, deals with the techno-typological study of lithic artefacts collected in the Colline Novaresi area. The main aim is to highlight aspects of the technological behaviour of the hunter-gatherer’s groups that inhabited the area, investigating the different exploitation strategies and the choices of the lithic resources.The absence of a stratigraphic context forces to base the identification of the different chronological horizons only on techno-typological criteria. Therefore, most of the lithic tools analysed remain indeterminate as far as this aspect is concerned, and sometimes only a generic distinction between Palaeolithic/Mesolithic and Neolithic is proposed. A most reliable chronological attribution is instead possible for retouched tools, Levallois cores and products and for laminar implements with clear technological attributes.The results obtained show that this area of Piedmont was inhabited during the Middle and Upper Palaeolithic, and an Epigravettian phase has also been recognized. A minority of the studied lithic tools refers to the Mesolithic. Considering that in the south-western margin of the alpine region the data on the Palaeolithic are very fragmentary, the technological study proposed here acquires importance in outlining a more precise scenario also for this part of the Italian peninsula.

Cosmogenic Cl-36 surface exposure dating of late Quaternary glacial events in the Cordillera de Talamanca, Costa Rica

AbstractGeomorphic evidence of past glaciation, such as U-shaped valleys, aretes, glacial lakes, and moraines, is preserved in the highland surrounding Cerro Chirripó in the Cordillera de Talamanca, Costa Rica. Previous work to establish a glacial chronology has focused on relative age dating of moraines and on radiocarbon dating of basal lake sediments to infer the timing of deglaciation. We used cosmogenic 36Cl surface exposure dating to constrain the ages of moraines within two formerly glaciated valleys, the Morrenas and Talari valleys. Forty-nine boulder samples were processed and measured from four moraine complexes in the Morrenas Valley and two moraine complexes in the Talari Valley. The exposure ages of these samples indicate a major glacial event occurred in this area from ~25 to 23 ka, broadly synchronous with the global last glacial maximum. Our results also indicate periods of glacial retreats and standstills from the deglacial period to the Early Holocene (~16–10 ka) before the complete disappearance of glaciers in this highland. These findings provide important insights into the glacial chronology and paleoclimate of tropical America.

Messinian Salinity Crisis and Quaternary glacial events shaped genetic diversification in Siculo-Maghrebian blister beetles (Coleoptera: Meloidae)

Messinian Salinity Crisis and Quaternary glacial events shaped genetic diversification in Siculo-Maghrebian blister beetles (Coleoptera: Meloidae)

Phylogeography of a widespread terrestrial vertebrate in a barely-studied Palearctic region: green toads (Bufo viridis subgroup) indicate glacial refugia in Eastern Central Asia

The phylogeography of western Palearctic species is relatively well studied, but data on Eastern Central Asia are scarce. We present one of the first data sets from a widespread terrestrial vertebrate (Bufo pewzowi) inhabiting Eastern Central Asian mountains and deserts to gain knowledge on its phylogeography in this region. We applied combined phylogenetic and demographic analyses to understand the evolutionary history using mitochondrial DNA D-loop variation of toads from 37 locations. Genetic structure of Bufo pewzowi is strongly affected by landscape: we found three haplotype groups in eastern Kazakhstan, Dzungaria and Tarim Basin, divided by the Tian Shan and Dzungarian Alatau ranges. A vicariant hypothesis may explain divergence among groups. The divergence time of the three major clades was estimated about 0.9 million years ago (confidence interval 0.5-1.4), and is discussed with respect to Quaternary uplifting and glaciation in the Tian Shan. Demographic analyses provided evidence for both historical bottlenecks and population expansions and suggested Pleistocene signatures. Glacial refugia were inferred in the Tarim Basin (around the Turpan depression), in southern Dzungaria (Urumqui region), at the northern foot of the Tian Shan (Gongnaisi) and perhaps at the Altai range (Terekti). Regional Post-Last Glacial Maximum dispersal patterns are proposed. A taxonomic hypothesis is presented. This study provides a detailed history of how a widespread terrestrial vertebrate responded to geological change and Quaternary glacial events in Eastern Central Asia and may have significance for future phylogeographic research in this understudied region.

Synoptic climate change as a driver of late Quaternary glaciations in the mid-latitudes of the Southern Hemisphere

Abstract. The relative timing of late Quaternary glacial advances in mid-latitude (40-55° S) mountain belts of the Southern Hemisphere (SH) has become a critical focus in the debate on global climate teleconnections. On the basis of glacial data from New Zealand (NZ) and southern South America it has been argued that interhemispheric synchrony or asynchrony of Quaternary glacial events is due to Northern Hemisphere (NH) forcing of SH climate through either the ocean or atmosphere systems. Here we present a glacial snow-mass balance model that demonstrates that large scale glaciation in the temperate and hyperhumid Southern Alps of New Zealand can be generated with moderate cooling. This is because the rapid conversion of precipitation from rainfall to snowfall drives massive ice accumulation at small thermal changes (1-4°C). Our model is consistent with recent paleo-environmental reconstructions showing that glacial advances in New Zealand during the Last Glacial Maximum (LGM) and the Last Glacial Interglacial Transition (LGIT) occurred under very moderate cooling. We suggest that such moderate cooling could be generated by changes in synoptic climatology, specifically through enhanced regional flow of moist westerly air masses. Our results imply that NH climate forcing may not have been the exclusive driver of Quaternary glaciations in New Zealand and that synoptic style climate variations are a better explanation for at least some late Quaternary glacial events, in particular during the LGIT (e.g. Younger Dryas and/or Antarctic Cold Reversal).

Cianobactérias e outros componentes das esteiras microbianas lisas da lagoa Pitanguinha, Região dos Lagos, Rio de Janeiro, Brasil

CYANOBACTERIA AND OTHER COMPONENTS IN THE SMOOTH MICROBIAL MATS FROM PITANGUINHA LAGOON, LAGOS REGION, RIO DE JANEIRO, BRAZIL. Pitanguinha Laggon is part of a set of small hipersaline lagoons known as Lagos region, placed in the northern Rio de Janeiro littoral, near Araruama city. They are genetically related to the last Quaternary glacial events and the sea level changes. The microbial mats formed around their margins are being affected by the advance of urbanisation and by salting exploration and are now threatened. The climatic conditions, with a semi-arid climate and warm temperatures stimulate the high evaporation rate. Many kinds of algalic mats growing up in their bottoms, associated with bioclastics and the lithified substrate of the lagoon. The composition of the smooth microbial mats and the associated organic rests are analyzed in this work. The study was carried out monthly on five sampling stations. The mats are stratified and filamentous forms dominante in the upper layer. Thirty seven species of cyanobacteria were identified, being Lyngbya aestuarii Liebman ex Gomont (1892) the more frequent. Specimens of Synechococcaceae Komarek and Anagnostidis, 1995 are the most abundant. Shells of bivalves, gastropods, foraminifers and ostracods occur together as associated bioclasts and have a critical role in the structure of the mats, being the source of calcium carbonate resulting from the chemically and physical action of the cyanobacteria over their skeletal remains. It attests that the cyanobacteria are the primary producers, located at the basis of the microbial food web in the microbial mats.

Pereletki and the initiation of glaciation in Siberia

Abstract Modern glaciers present in northern Siberia, adjacent to the Arctic Ocean littoral, develop through the gradual accumulation of windblown snow and firn in river valleys and other depressions. Such snow glaciers (“pereletki”) are largely ephemeral in nature, and produce landscapes dominated by nivation hollows and other snow-related landforms. Deposits associated with pereletki include nival, nival-solifluctionary, and fluvio-nival units. The modern pereletki are considered to represent an initial form of glaciation, and their development can be regarded as an analogue for the formation of nival deposits commonly attributed to a more extensive Sartanian glacial event. Late Quaternary glacial events in Siberia involved both alpine and piedmont glaciation, and widespread development of pereletki in lowland areas. Distinguishing between features and sediments produced by glacial ice, and those attributable to ephemeral pereletki, is necessary for accurate assessment of Late Quaternary glaciation in Siberia

Laurentide, cordilleran, and montane glaciation in the western Peace River — Grande Prairie region, Alberta and British Columbia, Canada

Geological investigations over the last decade in the western Peace River-Grande Prairie district of northwestern Alberta and northeastern British Columbia have provided important chronostratigraphic information regarding Laurentide, Cordilleran and Montane Quaternary glacial events. Numerous 14C age determinations, as well as stratigraphic and sedimentological analyses of numerous exposures, indicate that this area was first glaciated by Cordilleran ice sometime before the Late Wisconsinan. During the Late Wisconsinan, ca. 22,000–14,000 BP, Laurentide glacier ice covered much of the area. Between approximately 15,000 and 10,000 BP, Montane ice affected only the western part of the Peace region. There is no evidence for synchroneity of the ice advances and, therefore, no evidence for ice coalescence in this region. The resultant ‘ice-free-corridor’ was most likely a laterally fluctuating zone which existed during a several thousand year period in the Late Pleistocene. Climatic conditions along the ‘corridor’ during this period were probably unfavorable for human migration, but adequate for some plants and small animals. Numerous isolated areas along the western foothills of the northern Rocky Mountains, west of the Laurentide glaciation limit, were never glaciated during the Late Wisconsinan.

Quaternary glacial events in the Pyrenees from U-series dating of speleothems in the Niaux-Lombrives-Sabart caves, Ariège, France

Located at approximately 150 m above the present base level, the caves of Niaux, Lombrives and Sabart are an old drainage system, which worked between the Vicdessos and Ariege Valleys. In these caves, three successive sedimentary units were studied in detail. Each unit consists of two parts: the lower deposit is detrital, of fluvial origin, and testifies to a hydrological working of the conduit system; the upper deposit of each unit is mostly speleothems, corresponding to a draining of the conduits as the palcokarst evolved above base level. This is similar to the present environment of the caves. Only the speleothems from the upper part of each unit were dated by the 230Th/234 U method. The dates, from 27 samples, are in good agreement with Europe and North America data. The data from the middle (250 to 200 ka BP) and upper (90 to 20 ka BP) fluvial sediments correspond to major glacial events, which re-activated the karst system. Two further events resulted in a lack of carbonated sedimentation, the firs...