Pleistocene Chronostratigraphy Research Articles

Late Pleistocene chronostratigraphy and biostratigraphy of Mentelle Basin and its implications for global correlation

An accurate and high-resolution age model in marine sediments is essential for reconstructing past oceanographic and climate changes. The southeastern Indian Ocean is an important component of oceanographic circulation and global climate. However, the integrated biostratigraphy for the Late Pleistocene interval is not well known in the region. To address this issue, we constructed a new chronology for International Ocean Discovery Program (IODP) Hole U1516B in the Mentelle Basin, offshore southwestern Australia. We employ planktonic foraminifera δ18O to construct an astronomically tuned age model for Hole U1516B. Biostratigraphic analysis was performed for Hole U1516B using planktonic foraminifera, nannofossils, radiolarian taxa and diatoms. Seven planktonic foraminifera events are recorded, including the PT1a and PT1b boundaries. Eight nannofossil events were recorded including the boundaries between CN14a, CN14b and CN15. The planktonic foraminifera datums marked in Hole U1516B are mostly synchronous with datums reported in the southern hemisphere but are diachronous with datums in the northern hemisphere. The nannofossil datums marked in Hole U1516B have a close affinity with globally reported datums but small inconsistencies are probably due to strong ecological control. The diatom events are inconsistent and only recorded in short intervals during interglacials and several key radiolarians taxa are absent.

Late Pleistocene eruptive recurrence in the post-collisional Mt. Hasan stratovolcanic complex (Central Anatolia) revealed by zircon double-dating

Mt. Hasan (3262 m) is the second highest stratovolcano in Central Anatolia, Turkey, and is considered active based on a ca. 9 ka explosive summit eruption that was arguably depicted in a Neolithic mural at the nearby Çatalhöyük archaeological site. Besides evidence for Holocene activity of Mt. Hasan, its eruptive chronostratigraphy and hazard potential remain poorly constrained. Here, we apply (U–Th)/He thermochronology in combination with U–Th–Pb crystallization ages (zircon double-dating), including a novel population-based approach to disequilibrium correction of (U–Th)/He data, in an attempt to determine the eruption ages of strategically sampled lavas and pyroclastic deposits and to refine the Late Pleistocene chronostratigraphy of Mt. Hasan.During the Late Pleistocene, Mt. Hasan erupted multiple interfingering andesitic lava flows along with block-and-ash-flows. Seven of these lava flows, typically the stratigraphically youngest in a particular segment around the two central vents of the volcano, yielded Late Pleistocene eruption ages between 91.9 ± 3.9 and 18.1 ± 2.4 ka (uncertainties stated at 1σ). An even younger block-and-ash-flow was deposited on the western flank of the volcano at 13.5 ± 1.5 ka, which together with a ca. 9 ka small-volume explosive summit eruption define the youngest activity at the main edifice of Mt. Hasan. Collectively, these data indicate a Late Pleistocene recurrence of at least one eruptive phase every ca. 5–15 ka. New volume estimates for the Quaternary edifice of ~130–180 km3 translate into an integrated long-term eruptive magma flux of ~0.3 km3/ka, which is just slightly higher than Late Pleistocene flux estimates based on lava flow geochronology and volumes determined by analysis of digital elevation models. This long-term eruptive flux estimate is similar to those of stratovolcanoes in continental arcs, indicating that eruptive productivity in post-collisional settings can match that of active continental margins. All Mt. Hasan eruptions, including the Holocene event, sampled zircon which crystallized coeval with earlier eruptive phases, indicating longevity of the magma plumbing system. Along with ongoing fumarole activity and evidence for mid-crustal low seismic velocity zones, this suggests that a subvolcanic magma reservoir remains active to the present day.

Pliocene and Pleistocene chronostratigraphy of continental sediments underlying the Altiplano at La Paz, Bolivia

Continental sediments underlying the Altiplano plateau provide insight into the late Cenozoic evolution of the Central Andes. We characterize the magnetostratigraphy and lithostratigraphy of the upper part of this fill sequence along a transect extending southwestward from the Cordillera Real at La Paz, Bolivia, where it is best exposed. Multiple polarity reversals and the locally extensive, 2.74-Ma Chijini Tuff enable correlation between our six sections and three previously reported sections. The tuff ties the composite polarity sequence to the geomagnetic polarity time scale, demonstrating that the stratigraphic record extends from the latest Gilbert Chron (ca. 3.8 Ma) to the late Olduvai subchron (ca. 1.8 Ma), or possibly Jaramillo subchron (ca. 1.0 Ma). The sequence provides Earth's longest known record of low-latitude glaciation and the only record of Pliocene tropical glaciation. It includes evidence for 16 late Pliocene and Early Pleistocene glaciations, separated by interglacials of sufficient length (>103-104 a) to produce mature soil profiles. Successively larger ice caps formed directly before, during, and after the globally warm mid-Piacenzian (3.265–3.025 Ma), and throughout Plio-Pleistocene climate deterioration. The late Pliocene glacial units predate the onset of widespread Northern Hemisphere continental glaciation and in most cases unambiguously correspond to specific cool peaks of the astronomically tuned, benthic oxygen isotope (δ18O) record, including marine isotope stages MG2, M2, KM2, and G10. The glacial events broadly coincide with those nearer both poles, suggesting inter-hemispheric climate linkages. The early formation and subsequent expansion of ice caps beyond glacier margins of the Last Glacial Maximum suggest that the Cordillera Real likely attained its modern height before ca. 3.4 Ma. The number and timing of glaciations, and long-term sediment accumulation and incision rates suggest that the local Altiplano surface formed by ca. 1.8 Ma, after which headwaters of the Amazon River system breached the Cordillera Real and began to incise the fill sequence. The sequence spans at least 2 Ma before and during the first main pulses of the Great American Biotic Interchange, providing an important record of faunal migration. The arrival of savanna-adapted North American mammals in the Central Andes during this period points to the influence of glaciation on faunal migration in the southern tropics, similar to influences proposed in North and Central America.

A new MIS 3 radiocarbon chronology for Mochena Borago Rockshelter, SW Ethiopia: Implications for the interpretation of Late Pleistocene chronostratigraphy and human behavior

With excavated layers spanning a period from >49ka to ~36ka, Mochena Borago Rockshelter reveals a complex sequence of Late Pleistocene human occupation punctuated by volcanic events. Fifty-nine radiocarbon ages make Mochena Borago one of the best-dated Late Pleistocene archaeological sites in eastern and northeastern Africa. However, complex site formation processes, dramatic stratigraphic differences between non-contiguous excavation areas, and “outlier” dates that appear in various parts of Mochena Borago's sequence, complicate efforts to develop a secure and detailed chronology for local and regional behavioral changes. This article focuses on contiguous squares within the Block Excavation Area (BXA) trench at the northern end of the shelter. Bayesian modeling of thirty-seven dates from six major lithostratigraphic units within the BXA yields a revised series of age ranges; these differ from the previous age model (derived from weighted means) in subtle but important ways. Perspectives gained through Bayesian analysis stimulate more careful consideration of the complex site formation processes operating at Mochena Borago, the contextual integrity of the site's robust and distinctive flaked stone artifact assemblages (lithics), and potential correlations between lithic changes and environmental events that occur on local, regional, and global scales. As these factors come into focus, Mochena Borago can serve as an important chronological benchmark to better understand human behavior in eastern and northeastern Africa around the time of the second major dispersal of Homo sapiens.

Late Pleistocene chronostratigraphy and ice sheet limits, southern Ireland

The morpho-stratigraphic subdivision of the surficial glacial drifts of Ireland into ‘Older Drift’ and ‘Younger Drift’ is a long-standing convention in Irish Quaternary studies. Across southern Ireland a broad swath of terrain has traditionally been interpreted as Munsterian (penultimate glaciation) in age and large end moraine complexes bordering this zone of ‘Older Drift’ such as the ‘South Ireland End Moraine’ have long been regarded as marking the limit of the Late Midlandian (last glaciation) ice sheet. Sedimentary sequences exposed along the south coast of Ireland provide a window into the stratigraphy of the ‘Older Drift’ and have been studied for over a century. The present paper supports a fundamental revision of the traditional interpretation of ice sheet limits in southern Ireland and argues for an extensive last Irish Ice Sheet which covered much of the area of the Older Drift at the Last Glacial Maximum. The basis for this revision is threefold. Firstly, nineteen new optically stimulated luminescence (OSL) dates on the Courtmacsherry Raised Beach and overlying shallow marine sands demonstrate that on the south coast the beach and shallow marine sands formed during marine isotope stages 4–3. Secondly, AMS radiocarbon dates on reworked shells from the ‘Irish Sea Till’, demonstrate that this till and overlying ‘inland’ tills from central and SW Ireland were formed after ∼24calkaBP. Thirdly, new OSL dates of 24–21kaBP from deglacial outwash overlying the Irish Sea Till. Collectively these data are consistent with a last glaciation age for the glacigenic sequence along the south coast of Ireland, thus supporting a fundamental revision of the age of the Older (Munsterian) Drifts of southern Ireland. Most of southern Ireland was glaciated during the LGM and the moraine belts which have traditionally been interpreted as marking the last glacial limit such as the South Ireland End Moraine are reinterpreted here as recessional features formed during ice sheet retreat.

Characteristics for the recognition of Pliocene and early Pleistocene marker tephras in central Japan

Abstarct Numerous widespread tephra layers of late Pleistocene and Holocene age have been known since the early 1970s and greatly contribute to palaeoenvironmental reconstruction in the Japan islands and adjacent seas. However, the mapping of older tephra deposits has developed more slowly. Recent progress in describing many tephras occurring in the Pliocene and early Pleistocene uplifted marine and terrestrial deposits has resulted both from developments in the characterization of their component phases, their radiometric and geomagnetic dating and from an enhanced knowledge of their distribution. This study has constructed tephra correlations using the trace element composition of volcanic glass determined by ICP-AES analysis. Consequently, many widespread tephra layers of Pliocene and early Pleistocene age have been identified and can now be correlated extensively in central Japan. This paper catalogs these tephras, and provides the fundamental criteria for the establishment of a regional Pliocene–Pleistocene chronostratigraphy in central Japan.

Lithology and stratigraphy of loess-soil series and cultural layers of Late Paleolithic campsites in Eastern Europe

Comparative analysis of the Late Paleolithic cultural layer occurrence in different regions of the East European Plain provided new materials on the Late Pleistocene chronostratigraphy. A majority of known sites are located within the areas of Late Pleistocene loess of eolian origin. It is not uncommon that loess forms only the upper member of the enclosing deposits overlying the cultural layer. Numerous radiocarbon dates available at present not only allow definition of the age of the sites themselves, but also elucidation of the sequence of changes in climate and environments reflected in horizons of paleosols and cryogenic formations. The sedimentary series enclosing the Late Paleolithic cultural layers differ from the surrounding area in completeness of stratigraphic record and in sequence of cycles of sedimentogenesis. The ground surface at the campsites was stable at the time when eolian sedimentation on the surrounding areas was gaining in intensity. It is not inconceivable that the sites were chosen for human dwelling due to this specific feature.

Pleistocene chronostratigraphy in Estonia, southeastern sector of the Scandinavian glaciation

Abstract Pleistocene chronostratigraphy in Estonia is based on 29 studied sites/sections, the dating of which covers a span from approximately 200 ka BP to the Pleistocene—Holocene chronostratigraphic boundary, and a local varved clay chronology for eastern Estonia, which enables tentative correlation of Lateglacial (LG) events to Finnish and Swedish varve chronologies. Analysis of existing and unpublished data was used to review the current Pleistocene chronostratigraphy and particularly the history of Weichselian Cold Stage in Estonia. OSL ages from fluvial deposits that included the Korvekula (Holsteinian) or Rongu (Eemian) continental interglacial deposits revealed that the pre-Weichselian interglacial deposits were glacially dislocated during the Weichselian. Available OSL/TL and 14 C dates and new 14 C AMS ages of mammoth bones indicate ice-free conditions between 105 and 68 ka BP and a comparatively mild Middle Weichselian between 43 and 22 ka BP. The LG chronology indicates in general rapid (average 110 m/yr) deglaciation of the territory between ca 14.7 and 12.7 ka BP. The duration of the Late Weichselian glaciation in Estonia ranged between 7.3 and 9.3 ka.

Re‐interpretation of the Meikirch pollen record, Swiss Alpine Foreland, and implications for Middle Pleistocene chronostratigraphy

AbstractThe Meikirch drilling site in the Swiss Midlands north of Bern is re‐interpreted using a combination of sedimentological logging, pollen analyses and luminescence dating. The sedimentary sequence comprises about 70 m of lacustrine deposits, overlain by about 39 m of coarse glacial outwash interpreted to represent at least two independent ice advances. Pollen analyses of the apparently complete limnic sequence reveal a basal late glacial period followed by three warm phases that are interrupted by two stadial periods (Meikirch complex). The warm periods were previously correlated with the Holsteinian and Eemian Interglacials. According to luminescence dating, and with consideration of evidence for Middle Pleistocene climate patterns at other central European sites, a correlation of the Meikirch complex with marine isotope stage (MIS) 7 is now proposed. If this correlation is correct, it implies the presence of three intervals with interglacial character during MIS 7. However, the late Middle Pleistocene vegetational features of the Meikirch complex show significant differences when compared with the pollen record from the Velay region, central France. Possible explanations for this discrepancy are distinct Middle Pleistocene patterns of atmospheric circulation over central Europe and a different distribution of vegetation refugia compared to the Eemian Interglacial and the Holocene. Copyright © 2005 John Wiley & Sons, Ltd.

Pliocene and Pleistocene Chronostratigraphy and Paleoenvironment of the Central Arctic Ocean, Using Deep Water Agglutinated Foraminifera

Deep-water agglutinated foraminifera (DWAF) were studied from Cores PS2177-5, PS2200-5, PS2212-3 and PS2185-6; from the R/V POLARSTERN ARK-VIII/3 Cruise in the central Arctic Ocean. The sediments were non-calcareous containing a sparse assemblage of eleven DWAF species. A chronostratigraphic framework is presented for Cores PS2200-5 and PS2185-6. Paleoenvironmental data suggests a bathyal environment (2000-4000m) affected by water masses in the Arctic Ocean. The taxonomy of all of the DWAF found is presented and illustrated. A new species of the Family Trochamminidae; Trochammina lomonosovensis n. sp. is described and illustrated.

High-Precision Late Pleistocene Chronostratigraphy of a Gulf Coast Shelf-Edge Delta: ABSTRACT

High-Precision Late Pleistocene Chronostratigraphy of a Gulf Coast Shelf-Edge Delta: ABSTRACT

Analyse pollinique du remplissage pleistocène inférieur et moyen de la grotte du Vallonnet (Roquebrune — Cap-Martin, Alpe-Maritimes)

Palynologie analysis of lower and middle pleistocene filling of Vallonnet cave, has allowed to show three great climatic stages. Inside bottom of stalagmitic floor and beach deposits, an important wooded shelter determines a hot and wet climate similar to an interglacial climate. At the level of unconsolidated filling, steppic feature of lands cape seems correspond to cool, but little damp climate of a glacial period. In the sealing stalagmite, pollens of individualized wooded shelter suggest the return of a temperate hot damp climate, probably contemporaneous with a new interglacial stage. Occurence of a single exotic taxon (Pterocarya) at the basis of diagram, does not allow to precisely assign the different stages of cave filling in the lower pleistocene chronostratigraphy.

Vegetation and its Environment in Denmark in the Early Weichselian Glacial (Last Glacial)

The present work deals with the layers found above certain Eemian Interglacial fresh-water deposits in Denmark. Earlier investigations at these sites had indicated a "Lower Temperate Stage" and an "Upper Temperate Stage" separated by clay layers ("Middle Bed"). The existence of an upper temperate stage has been doubled by some authors. The "Lower Temperate Stage" is now usually considered the Eemian Interglacial, and the post-Eemian layers have been referred to the Last Glacial of Northern Europe, or the Weichselian Glacial, which may be defined as the time interval, which separated the Eemian Interglacial from the Postglacial. Methods of investigation are described in the chapters II-III. The basis for establishing the pollen diagrams is discussed, and it is maintained that the pollen zones should be considered bio-stratigraphic units. Problems in the identification of pollen grains and spores are discussed, and selected identifications are mentioned briefly. Statistical observations are mentioned in a special part. Chapter IV deals with the individual sites investigated, and their sediments and pollen diagrams. It can be shown that certain layers earlier referred to the "Upper Temperate Stage" contain abundant plant fossils rebedded from the Eemian Interglacial layers, but layers of interstadial character also occur. The segregation of the secondary (rebedded) elements in the fossil floras, and zonation of the pollen diagrams are discussed. The chapter on the earlier vegetation and its environment includes a discussion of various problems in palaeoenvironmental analysis. The vegetation and indications of temperature, precipitation and soil conditions in the various pollen zones are discussed. A list of remains of higher plants referred to the pollen zones is presented with indications of their probable primary or secondary status. The primary flora is compared with the Danish Late-Glacial flora. The chapter on climatic development and chronology deals first with principles of Pleistocene chrono-stratigraphy. The author supports the opinion that climatic changes may serve as chronological limits. Glacials and interglacials constitute main stages, and stadials and interstadials are considered substages within the glacials. Vegetational succession and climatic changes within the sequence studied are summarized in table 24 (p. 115). The limit between the Eemian Interglacial and the Weichselian Glacial is distinguished as a large decrease of temperature. The Rodebæk and the Brørup Interstadials, two interstadials within the early Weichselian Glacial, are delimited by temperature changes. Some of the layers earlier referred to the "Upper Temperate Stage" mentioned above belong to the Brørup Interstadial. The probable composition of the vegetation in Northern Europe in the early Weichselian Glacial is mentioned. A development similar to the Danish sequence occurred in the Netherlands, and various plant-bearing deposits from Germany, Poland and England can be correlated with these sequences. Finally, radiocarbon dates are mentioned. The Amersfoort (Rodebæk) Interstadial is dated at 64 000 years before present, and the Brørup Interstadial at 59 000 years before now. Other "old" dates from Germany, England and Italy are mentioned. The results corroborate Emiliani's palaeotemperature curve.