•Pollen from sediments in Taiwan Strait originate from Taiwan and Southeastern China.•Dominance of Pinus reveals a cool, wetter climate with decreasing sea level in MIS4.•Dominance of herb and alpine ...conifers taxa signify a colder climate during LGM.•Holocene is dominated by Pinus and ferns, denoting the climate was comparable to the present day.
Studies on the reconstruction of long-term climatic and vegetation dynamics around the northern South China Sea (SCS) are limited. Therefore, this study was conducted to get a clear understanding of the paleoenvironmental significance around the Taiwan Strait in northern SCS. The chronology was based on the accelerator mass spectrometry (AMS) 14C dates of mixed planktonic foraminifera, then we compared and cross-validated the age–depth model based on the grain-size analysis and foraminifera data. Palynomorph data, including percentages and concentrations based on marine sediment cores (WQZK1, WQZK2, and WQZK3), were used to reconstruct the history of vegetation and climate changes and identify the provenance and transport mechanisms of pollen and spores. The findings indicated that fern spores dominated the interglacial period, suggesting intense summer monsoons during warm periods in marine isotope stages (MIS) 5–MIS 1. During MIS 5a, tropical and subtropical conifers with temperate components dominated, indicating the climate was comparatively warm at an increasing sea level. The lowest sea level subtly proved cooler and wetter climate, subsequently affecting a drastic increase of Pinus during MIS 4. Tropical and subtropical conifers dominated during the MIS 3, and the sea level increased comparatively to MIS 4, indicating warmer climate conditions. Pinus pollen and fern spores dominated MIS 1, implying that the paleoenvironment was comparable to the present day. Therefore, this study supports previous studies on the northern SCS region and suggests that a combination of pollen with other proxies provides a better understanding of vegetation and climatic dynamics in the past.
Loess sequences are widely distributed in semi-arid regions around the world, and are sometimes also located in coastal zones. The accumulations of coastal loess provide a valuable record of both ...climate and sea-level changes. Here we report sedimentological and high sampling resolution luminescence dating evidence for such changes from two loess sequences from the Shandong Peninsula and Miaodao Archipelago near the coast of Bohai Sea in northern China. Both the quartz optically stimulated luminescence (OSL) and K-feldspar post-infrared IRSL (pIRIR290) signals show consistent and satisfactory luminescence characteristics up to ∼100 ka, while the K-feldspar pIRIR290 ages provide age control up to ∼200 ka and are in stratigraphic order. With this fully independent age model, our results reveal that coastal loess accumulation is episodic with a high variability in apparent accumulation rates. After comparing with global and regional sea-level records, we find that the intervals with high accumulation rates coincide with global low sea-level stages, and that the loess sedimentary hiatuses indicated by nearly zero or very low accumulation rates at one site mainly correspond to global high sea-level stages, indicating the dominant role of global sea-level changes on coastal loess accumulation in the study area. We therefore conclude that regional marine regression mainly occurred during MIS 6, and MIS 5b to MIS 2, with extremely low regional sea levels possibly around 150 ka, 70–60 ka and 37–24 ka, while high sea-levels occurred during MIS 5e–5c and MIS 1. This study implies that coastal loess deposits with a good chronology could be used to constrain the timing of regional sea level change.
•We provide a robust, high-resolution luminescence age model for coastal loess.•Coastal loess in northern China was accumulated episodically during the past 200 ka.•The lowest sea levels occurred at 150, 70–60 and 37–24 ka in Bohai Sea, northern China.
Many coasts feature sequences of Quaternary and Neogene shorelines that are shaped by a combination of sea-level oscillations and tectonics. We compiled a global synthesis of sea-level changes for ...the following highstands: MIS 1, MIS 3, MIS 5e and MIS 11. Also, we date the apparent onset of sequences of paleoshorelines either from published data or tentatively extrapolating an age for the uppermost, purported oldest shoreline in each sequence. Including the most documented MIS 5e benchmark, we identify 926 sequences out of which 185 also feature Holocene shorelines. Six areas are identified where elevations of the MIS 3 shorelines are known, and 31 feature elevation data for MIS 11 shorelines. Genetic relationships to regional geodynamics are further explored based on the elevations of the MIS 5e benchmark. Mean apparent uplift rates range from 0.01±0.01mm/yr (hotspots) to 1.47±0.08mm/yr (continental collision). Passive margins appear as ubiquitously uplifting, while tectonic segmentation is more important on active margins. From the literature and our extrapolations, we infer ages for the onset of formation for ~180 coastal sequences. Sea level fingerprinting on coastal sequences started at least during mid Miocene and locally as early as Eocene. Whether due to the changes in the bulk volume of seawater or to the temporal variations in the shape of ocean basins, estimates of eustasy fail to explain the magnitude of the apparent sea level drop. Thus, vertical ground motion is invoked, and we interpret the long-lasting development of those paleoshore sequences as the imprint of glacial cycles on globally uplifted margins in response to continental compression. The geomorphological expression of the sequences matches the amplitude and frequency of glacial cyclicity. From middle Pleistocene to present-day, moderately fast (100,000yrs) oscillating sea levels favor the development of well identified strandlines that are distinct from one another. Pliocene and Lower Pleistocene strandlines associated with faster cyclicity (40,000yrs) are more compact and easily merge into rasas, whereas older Cenozoic low-frequency eustatic changes generally led to widespread flat-lying coastal plains.
Current multi-proxy studies on a long sediment sequence preserved at Sokli (N Finland), i.e. in the central area of Fennoscandian glaciations, are drastically changing classic ideas of glaciations, ...vegetation and climate in northern Europe during the Late Pleistocene. The sediments in the Sokli basin have escaped major glacial erosion due to non-typical bedrock conditions. In this review, the Sokli record is compared in great detail with other long proxy records from central, temperate and northern, boreal Europe. These comprise the classic records of La Grande Pile (E France) and Oerel (N Germany) and more recently obtained records from Horoszki Duże (E Poland) and Lake Yamozero (NW Russia). The focus of the review is on pollen, lithology and macrofossil- and insect-based temperature inferences. The long records are further compared with recent proxy data from nearby terrestrial sites as well as with the rapidly accumulating high-resolution proxy data from the ocean realm. The comparison allows a re-examination of the environmental history and climate evolution of the Last Interglacial–Glacial (LI–G) cycle (MIS 5–2). It shows that environmental and climate conditions during MIS 5 (ca 130–70 ka BP) were distinctly different from those during MIS 4–2 (ca 70–15 ka BP). MIS 5 is characterized by three long forested intervals (broadly corresponding to MIS 5e, 5c, 5a), both in temperate and northern boreal Europe. These mild periods were interrupted by two short, relatively cold and dry intervals (MIS 5d and 5b) with mountain-centered glaciation in Fennoscandia. Millennial scale climate events were superimposed upon these longer lasting climate fluctuations. The time interval encompassing MIS 4–2 shows open vegetation. It is characterized by two glacial maxima (MIS 4 and 2) with sub-continental scale glaciation over northern Europe and dry conditions in strongly continental eastern European settings. High amplitude climate oscillations of millennial duration characterized the climate variability of MIS 3. Mild climate conditions in early MIS 3 caused large-scale deglaciation of the Fennoscandian Ice Sheet, and ice-free conditions with Betula-dominated vegetation (including tree birch) persisted over large parts of Fennoscandia, possibly interrupted by glaciation, during major part of MIS 3 till ca 35 ka BP. Overall, MIS 5 was mostly mild with warmest or peak interglacial conditions at the very start during MIS 5e. MIS 4–2 was mostly cold with most extreme or peak glacial conditions in the closing phase during MIS 2. This points to a subdivision of the last climate cycle into an early, overall mild interglacial half and a late, overall cold glacial half, each with duration of ca 50 ka. This review also shows that the climate variability in central and northern Europe during the LI–G cycle was mostly in degrees of continentality with major shifts in winter temperature and precipitation values; summer temperatures, on the other hand, remained largely unchanged. It points to the waxing and waning of sea-ice over the North Atlantic Ocean as a possible characteristic feature of the Late Pleistocene. The present compilation, based on long terrestrial sequences, high-resolution multi-proxy data from the oceans, and quantified paleo-climate data, strongly favors a definition of entire Marine Oxygen Isotope Stage 5 as the Last Interglacial similar as in the original marine stratigraphy and the stratigraphy at La Grande Pile in France. The proxy-based climate data places the start of the Last Glacial at the base of MIS 4 and the northwest European Pleniglacial. It shows that the division between the Eemian (MIS 5e) and the Early Weichselian (MIS 5d-a) is not useful, as not relevant from a climate point of view.
•European and marine proxy data provides new insights in MIS 5–2 climate evolution.•Study divides last climate cycle into early (MIS 5) mild and late (MIS 4–2) cold part.•Changes in degree of continentality characterized climate variability during MIS 5–2.•Summer temperatures generally fluctuated only slightly during last climate cycle.•Minor ice-cover over N Europe during MIS 3 persisted until ca 35 ka BP.
In this work, three important Pleistocene sites of the Madrid basin located close to the junction of the Manzanares (PRERESA site) and the Jarama (Valdocarros site and Maresa quarry) rivers have been ...studied in order to improve the existing chronological framework of the basin and to clarify the geological evolution of these fluvial systems and their relationship with human occupations. To do so, Electron Spin Resonance (ESR) dating was applied to four fossil teeth and nine optically bleached quartz grain samples. Most of the obtained dates are consistent with the existing preliminary age estimates by biostratigraphy, luminescence (OSL and TL) or Amino Acid Racemization (AAR) dating. This ESR dating study suggests an age of Late Middle Pleistocene (early MIS6) for PRERESA site. At the Jarama valley (Valdocarros site and Maresa quarry), the Arganda I unit could be correlated to the MIS 9 and MIS10, the Arganda II unit seems to belong to MIS8 and MIS7 and the Arganda III to the MIS6.
One of the conventional ways to construct Late Quaternary chronostratigraphic frameworks for archaeology in southern Africa is through archaeological technocomplexes. This practice is more developed ...in South Africa and Lesotho than in the northern areas of the region. The Still Bay, Howiesons Poort, Robberg, Oakhurst, and Wilton technocomplexes are widely recognized, whereas more ambiguity is associated with the Bambata, Tshangula, Pietersburg, Mossel Bay, Sibudu, Sibudan and early Later Stone Age. Technocomplexes are frequently defined in relation to generalized, typological attributes from lithic assemblages excavated over several decades at different sites with various levels of resolution. This might lead to coarse-level data that do not necessarily relate to changes in culture, cognition, climate or the environment. Here the relationship between lithic technology and the palaeoenvironment is explored from a constrained chronostratigraphic context in two technocomplexes from the southern Cape coast, the Mossel Bay from Klasies River Main site, and the Oakhurst from Klipdrift Cave. Significant changes in the shore habitat are not reflected at technocomplex level, but lithic densities and dimensions of the products vary more closely with environmental shifts. Although a close relationship between Marine Isotope Stages and technocomplexes cannot be unambiguously demonstrated, some aspects of lithic technology seem to be sensitive to palaeoenvironmental change. Technocomplexes have heuristic value to identify cultural patterns through time and space and they are useful in determining where gaps in evidence occur. Ordering stone tool assemblages using technocomplexes remains one of the main ways to construct archaeological chronologies, especially when refined dating results are not available, and for exploring archaeological cultural developments against the backdrop of paleoclimate fluctuations, especially between MIS 6 and 1.
Analyses of Mg/Ca in planktonic foraminifera Globigerinoides ruber (white) tests were made to evaluate burial influences and preservation before reconstructing paleotemperatures. We studied samples ...from the eastern Gulf of Mexico marine sediment core EN32-18PC at a glacial-interglacial scale. The core chronology is based on planktonic foraminifera biostratigraphy and δ18OG. ruber stratigraphy, showing that the core spans the biozones V2 - Y and the Marine Isotope Stages (MIS) 9 to 4 (i.e., 319.3 to 66.0 ka). Based on Scanning Electron Microscopy (SEM) and LA-ICP-MS analysis of Mg/Ca, Sr/Ca, Mn/Ca, Fe/Ca, and Mn/Fe ratios, we found evidence of test alteration by early diagenesis. Some tests show material infillings, pore reduction, polygonal patterns between pores, and wall thickening by calcareous overgrowth. Values of Mg/Ca >6 mmol/mol and δ18O > 2‰ must be carefully evaluated before reconstructions. Values of Mn/Ca >0.6 mmol/mol and Fe/Ca >0.2 mmol/mol indicate the adherence of clays or coatings (Mn or Fe oxides). Nevertheless, we did not find evidence of severe diagenesis in the tests (like recrystallization or euhedral crystals grown by inorganic precipitates); thus, their alteration degree is incipient, and calcite overgrowth is the most severe diagenetic effect during MIS-6 and early MIS-5. After calculating paleotemperatures, we obtained SST values comparable to other cores in the region (i.e., 24 °C - 31 °C). The paleotemperature record fluctuates over MIS 9 to 5, in agreement with the insolation intensity cycle controlled by precession. However, suborbital trends could not be reconstructed due to the studied effects imprinted on the specimens.
•LA-ICP-MS analyses in foraminifera unveil early diagenesis during MIS 9 to 5.•SEM analyses evidence clay infillings and calcite overgrowth.•Reconstructed SST values are within expected values at glacial-interglacial scale.
Palaeoshorelines and associated palaeo-coastal features are studied to reconstruct past sea level, climate, and depositional environments. Their identification typically depends on direct field ...observations and is therefore challenging in the marine environment, where the interpretation mostly relies on sparse geophysical data. This review presents, based on 118 published case studies, a summary of morphological evidence that can be used to identify submerged relict coastal features worldwide, using only geophysical data. Four coastal feature categories that can be used as palaeoshoreline indicators were identified: (1) beach ridges of wind and wave origin; (2) shoreface strata; (3) marine terraces; and (4) coral-reef terraces.
In light of this proposed classification, an area of ~200,000 km2 was investigated along the Rowley Shelf (North West Shelf, Australia), a carbonate-dominated platform, based on the integration of high-resolution bathymetry (i.e., seismic-derived bathymetry, satellite-derived bathymetry, multibeam echosounder bathymetry, spot depth soundings) and 2D reflection seismic lines. Relict features were discriminated from modern bedforms using five criteria: (1) stratigraphic position; (2) emersion features; (3) similarity with modern and published analogues; (4) integration of modern ocean conditions; and (5) evidence of early cementation. In total, over 500 submerged relict coastal features were identified, making this review the most comprehensive catalogue published to date.
Relict features are concentrated over specific depths, referred to as modal sea-level depths (MSLDs), which correspond to depths where the relative sea level remained stable over long periods of time. Nine MSLDs are observed at 20, 35, 50, 60, 70, 80, 90, 105 and 125 m below sea level. Each MSLD is the result of the accumulation of coastal features through multiple glacial/ interglacial cycles. Most of the features may nevertheless be related to the last glacial sea-level fall and were likely formed between Marine Isotopes Stages (MIS) 5 and 2.
The analysis of the submerged coastal features indicates that the overall shelf morphology is controlled by the distribution of these features, and that, while in a carbonate province, their formation is related to wind, tide, fluvial and wave processes. The higher concentration of relict fluvial-influenced features at shallower depths and of relict tide-influenced features at greater depths suggest that fluvial runoffs were limited during glacial periods. This, in turn, supports the hypothesis of a prevalent dry climate during glacial periods and in contrast, of a humid climate during interglacial periods. Finally, the study reveals that most modern coral reefs of the Rowley Shelf are growing on top of relict coastal features and that seabed ridges previously interpreted as drowned coral reefs are, in fact, likely to be relict coastal features formed through clastic processes.
Results from this study will support the identification of submerged palaeoshorelines on continental shelves around the globe and highlight the influence of associated relict coastal features on shelf morphologies. Additionally, this study provides new insights on processes shaping carbonate provinces.
The Last Abundant Appearance Datum of the endemic Southern Ocean diatom Hemisdiscus karstenii Jousé is dated at around 190,000 years Before Present, which provides a robust and convenient ...biostratigraphic marker to Late Pleistocene paleoceanographic studies. However, no prior studies have sought to understand what processes may have driven H. karstenii to extinction. We here present the first morphometric investigation of H. karstenii over Marine Isotope Stage (MIS) 10 to 6 (355,000 years to 150,000 years). The combination of these data to records of H. karstenii absolute abundances, Fragilariopsis kerguelensis biometry and absolute abundances, and southern high-latitude air and ocean temperatures over the past 355,000 years suggests that H. karstenii populations reduced their mean size and productivity in response to the rapid drop in temperatures across the MIS 7 to MIS 6 glacial inception. This prolonged cooling event may have pushed H. karstenii to its adaptive limit until it could not sustain physiological viability. The repetitive occurrence of very cold events during the early MIS 6 may have additionally prevented surviving populations of H. karstenii from re-establishing abundant communities leading to extinction late in MIS 6.
•First biometric study of the extinct diatom species Hemidiscus karstenii.•Smaller and less abundant H. kastenii are encountered during glacials than in interglacials.•LAAD of H. karstenii occurred during very harsh climate conditions.•Disappearance of H. karstenii during MIS 6 is due to its inability to adapt to very cold conditions.
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