Reliable Chronological Framework Research Articles

Multiple age control of young nebkhas in the Mu Us dune field, north-central China

Nebkhas, a unique type of biogeomorphological aeolian landforms formed by sand accumulation around plants, are widely distributed in arid and semi-arid regions globally. Previous studies have highlighted the potential of nebkha sediments as valuable archives for understanding past climate and environmental changes. However, establishing a reliable chronological framework for nebkha sediments has posed challenges due to the lack of suitable dating methods. In this study, we applied both the quartz OSL and K-feldspar pIRIR150 protocols to date nebkha sediments from three different sites within the Mu Us dune field in north-central China. Internal checks indicate that the quartz OSL protocol is suitable for equivalent dose measurements, though age determinations for some quartz samples with weak luminescence signals may be subject to uncertainties. K-feldspar exhibits brighter signal intensity and a higher signal-to-noise ratio, making K-feldspar pIRIR150 ages reliable, particularly when residual doses are low, luminescence signals are stable, and dose recovery ratios are satisfactory. The results indicate that the luminescence ages derived from both the quartz OSL and K-feldspar pIRIR150 protocols are comparable, and these ages align with stratigraphic sequences and independent 137Cs dating results. Based on the established chronologies, our findings suggest that some large nebkhas in the southwestern Mu Us dune field likely originated 100–200 years ago, possibly in response to either climate-driven or human-induced aridification in this region.

An integrated chronological study on the Quaternary sedimentary sequences of the Yangtze River delta, China

The sedimentary sequences of the Yangtze River delta comprise important Quaternary records of tectonics, sea-level oscillation, and climatic change; however, analysis is hampered by a lack of a reliable chronological framework. In this paper, we present an integrated chronology for two sedimentary sequences (core ZKW2 and ZKW4) on the southern side of the Yangtze River delta, based on magnetostratigraphy and absolute methods (OSL, 14C, and ESR dating). The basal ages of the core ZKW2 and ZKW4 are ca. 2.25 Ma and 2.96 Ma, respectively. The integrated chronology indicates significant increases in the sedimentary accumulation rate at ∼0.15 Ma, rather than the Matuyama-Brunhes boundary as indicated by magnetostratigraphy alone. The observed sedimentary transition is possibly controlled by regional subsidence of the Zhe-Min Uplift, and climate evolution during the last interglacial period.

Radiocarbon chronology of sediments with implications for climatic events in Lop Nur, NW China

Radiocarbon dating has played a pivotal role in paleoclimate research, particularly in establishing chronological sequences for lake sediment. However, the persistent challenge of the radiocarbon reservoir effect has remained a notable concern when using 14C dating. While several methods have been developed address this issue, the spatiotemporal variability of the lake reservoir and their climatic implications on the occurrence of anomalous 14C dating results have frequently been overlooked in previous studies. Especially when dealing with lake sediments in arid regions of Central Asia, the impact of climate-induced sediment sources and watershed hydrology poses substantial challenges for 14C dating. In this study, we focused on sediment profile in the Lop Nur and established a reliable chronological framework for the late Holocene using a piecewise linear regression approach. By integrating climate data from the surrounding region and archaeological evidence, we reconstructed the hydrological and aeolian processes of Lop Nur spanning from 670 BCE to 1300 CE. Our findings suggest that the anomalies observed in dating results were closely associated with the presence of sand component with a reduced organic matter content. And the record reveals the occurrence of sandstorm events around 500 BCE and 300 BCE, with a significant increase in strength after 200 CE. This indicates a decrease in reservoir effects during the lake regression, due to increased aeolian inputs. Therefore, we proposed that the deposition of larger-sized sandstorm particles during lake regression is predominant reason for reduced absorption of surrounding aged organic matter, leading to the younger age observed.

A loess-paleosol record of climate and vegetation change during the past 27,000 years from South-East of the Caspian Sea, Iran

Loess and paleosols are valuable terrestrial archives of past climate change in arid and semiarid Asia, yet most of the available records are located in central Asia and China, with only few records from western Asia. Here we report on a loess-paleosol sequence retrieved from the Gorgan Plain Southeast of the Caspian Sea that extends back to ca. 27,000 years ago. By combining palynological and micromorphological data with granulometry and magnetic properties in different horizons, we infer past changes in soil formation and vegetation composition, and the related climatic conditions. In order to set up a more reliable chronological framework, we applied luminescence and radiocarbon dating. Our results suggest a dry and cold glacial period characterized by steppe vegetation and loess deposition until about 24,000 years ago. Climate conditions during the Last Glacial Maximum (19–23,000 years ago) were relatively wet followed by a drying trend towards the end of the deglaciation. Our record suggests a relatively wet early Holocene but remains inconclusive for the late Holocene due to concurrent anthropogenic impact. We argue that changes in wintertime temperature and precipitation have been decisive in shaping the vegetation and soil formation in our study area during the Holocene, whereas changes in the position of the westerlies together with sea-level fluctuations of the Caspian Sea controlled the regional climate during the last glacial period.

Application of visual stratigraphy from line-scan images to constrain chronology and melt features of a firn core from coastal Antarctica

AbstractEstablishing an accurate chronology is crucial for interpretation of ice core-based climatic records. While high snow accumulation rates characterise coastal Antarctica, thus enabling recovery of highly resolved climatic records, summertime melting at such low-elevation sites offers challenges in establishing a reliable chronological framework through traditional approaches using the seasonality of stable water isotope and ionic proxy records. Here, we assess visual stratigraphy (VS) obtained from line-scan images as a proxy for annual layer counting in firn section (top 50 m) of the IND-36/B9 ice core (dated 1919–2016 CE) from the Djupranen Ice Rise in central Dronning Maud Land, East Antarctica. We also used these images to obtain melt history for the site and found that traditional thickness-based quantification of melt proportion results in significant overestimations. Since density has dominant control on VS profile over the firn section, we first used circulant single-spectrum analysis to remove the secular trend and then we extracted the seasonal VS signals attributed to dust and sea-salt inclusions. We find that melt layers do not significantly alter the VS records if masked during pre-processing. The age–depth model based on the reconstructed VS profile revealed an excellent match with identified time-markers within an uncertainty of ±2 years.

Determination of the optimized late Pleistocene chronology of a lacustrine sedimentary core from the Heqing Basin by geomagnetic paleointensity and its paleoclimate significance

Long and continuous lacustrine sedimentary sequences from SW China faithfully recorded the evolution of the Indian summer monsoon (ISM). However, the limited dating range (<50 ka) of 14C dating has restricted high-resolution research on the last glacial cycle.We presented a relative paleointensity (RPI) record from a lacustrine sedimentary core from the Heqing Basin to optimize its AMS 14C chronology. Detailed rock magnetic analyses indicated that SD and vortex state magnetite (and/or maghemite) was the dominant magnetic mineral of lacustrine sediments. Moderate variations in concentration-dependent (SIRM, ARM) and grain-size-dependent (ARM/SIRM) parameters satisfied the criteria for the RPI studies. Consequently, we determined the RPI by NRM20-40 mT/SIRM20-40 mT, where NRM20-40 mT denotes the NRM after demagnetization between 20 and 40 mT. Using 6 AMS 14C dates younger than 40 ka BP as constraints, 7 age control points were determined by correlating the lows in the RPI record with those of the target paleointensity stacks PISO-1500. We established a reliable chronological framework of the upper 11.1 m of the HQ drill core by binomial fitting based on the 7 RPI age control points and the climatic transition termination II. The consistent variations in our RPI curve and other global target paleointensity curves indicated that the optimized chronology was reliable.In our optimized chronology, the visible precession cycle in ARM/SIRM indicated that the ISM was a direct response to solar insolation during the last glacial cycle. The strong ISM suggested by the high content of Mesic conifers and tropical and subtropical trees during MIS 3 shifted to MIS 5a. Thus, the “MIS 3 Mega-paleolake” hypothesis in China, which was mainly deduced by the 14C age model, was challenged.

Luminescence dating of a sedimentary sequence in the eastern North Yellow Sea

Sediments from the Yellow Sea (YS) are important archives for investigating the stratigraphic evolution in relation to global and regional sea-level changes. Here, the upper 40-m-thick interval of a 100-m-long drill core (NYS17), retrieved from the eastern North Yellow Sea (NYS), were studied to explore the late Quaternary sedimentary history in this region. To obtain reliable chronological framework of the core, we utilized multiple luminescence signals from sediments for dating. Coarse-grained (CG) and fine-grained (FG) quartz optically stimulated luminescence (OSL), and K-feldspar/polymineral post-infrared (IR) IR stimulated luminescence (pIRIR50/150) signals were analyzed to obtain age estimates for comparison. Primary results show that quartz OSL ages are consistent with the corrected ages of IR50 and pIRIR150 signals. Chronostratigraphy of core NYS17 presents two phases of rapid accumulation. One is at the interval of 35.6–29.8 m deep, as age controls of sedimentary stratigraphy are in the period of 135–130 ka, corresponding to Marine Isotope Stage (MIS) 6/5. Another occurs in the upper section (14.5–0.9 m) as luminescence ages are constrained between 11 and 9 ka. However, the overlying deposits after 9 ka seem to be very thin in the core site. This is likely attributed to the abundant terrestrial sediment supply during the early Holocene and following starvation after further rise of the sea level and transgression. In contrast, the MIS 5–2 interval remains far to be exactly defined in the core as no age constraint is available. Regionally, correlations of chronostratigraphy of our core with other collected cores from the YS and East China Sea, show comparable depositional records for both the late Pleistocene and Holocene sedimentary successions. These findings indicate that the spatiotemporal variations of sedimentary processes in the YS shelf were closely linked to global sea-level changes during the glacial-interglacial cycles.

The sedimentary succession of the last 2.25 Myr in the Bohai Strait: Implications for the Quaternary paleoenvironmental evolution of the Bohai Sea

The Bohai Strait connects the Bohai Sea with the Yellow Sea, allowing material and energy exchange between the seas. The sedimentary record in this region is important for reconstructing the Quaternary sea-level changes and environmental evolution in the Bohai Sea area; however, long sedimentary sequences with a reliable chronological framework from this area are scarce. We assessed the sedimentary characteristics, grain size, microfossils, accelerator mass spectrometry 14 C ages and optically stimulated luminescence ages of core BHS01 from the Bohai Strait. From these and previous paleomagnetic results, new insights into regional sea-level changes and environmental evolution in the Bohai Strait over the last 2.25 Myr are obtained. The sedimentology and environmental proxies (benthic foraminifera and marine ostracods) indicate that the sedimentary environment of the area around core BHS01 was mainly dominated by fluvial–lacustrine deposits from 2.25 to 0.89 Ma, and subsequently by alternating marine and fluvial deposits. Comparative analyses of the chronological and sedimentary results of core BHS01 with previous drilling records in the eastern marginal seas of China revealed that the Quaternary initial marine transgression of the Bohai Sea occurred no later than 0.89 Ma (latest early Pleistocene) since Quaternary. The initial transgression presumably resulted from the partial subsidence and disintegration of the Miaodao Islands Uplift with sea-level rise during this period or slightly earlier. This result is generally consistent with the timing of the Quaternary regional marine transgressive processes of the Yellow and Bohai seas; thus, we propose a conceptual model in which the first marine transgression of the Yellow Sea and the Bohai Sea during the Quaternary occurred no later than 1.66 Ma and 0.89 Ma, respectively. This study provides new evidence for understanding the Quaternary sea-level changes and regional environmental evolution in the Bohai Sea. • Paleoenvironmental evolution of the Bohai Strait since ~2.25 Ma reconstructed. • Quaternary initial transgression of the Bohai Sea occurred no later than 0.89 Ma. • Conceptual model for Quaternary transgressive processes of the study area proposed.

Middle Miocene dinoflagellate cyst assemblages and changes in marine productivity in western Colombia

Changes in dinoflagellate assemblages indicate regional paleoceanographic events affecting western Colombia. Integration of palynomorph, planktonic foraminifera, and calcareous nannoplankton data from a 616 m thick outcrop section in the Ladrilleros-Juan Chaco region allows the construction of a detailed and reliable chronological framework and identification of marine high-productivity intervals. Results indicate marine deposition from middle (~15 Ma) to late (~10 Ma) Miocene. Dinoflagellate cyst assemblages are consistent with known regional assemblages and include more warm water taxa than cold ones. Correlation of the palynomorphs with the other microfossils studied allows calibration of the biostratigraphic ranges of seven species of dinoflagellate cysts commonly reported from tropical zones. The ratio between autotrophic and heterotrophic dinoflagellate cysts indicates an overall increase of paleoproductivity at ~13.8 Ma. Gonyaulacoid taxa dominate the lower interval (15–13.8 Ma), while peridinioid taxa dominate the upper segment (~13.8–10.5 Ma). This change coincides with the global cooling related to the growth of the Antarctic ice sheet (~14 Ma) and presumably increased the recurrence of events like La Niña in the equatorial Pacific. These conditions increased the primary productivity in the Pacific coastal region of northwestern Colombia, and four high-productivity intervals are tentatively correlated to the Mi3a, Mi-3b, Mi-4, and Mi-5 isotope events.

High-resolution palaeoenvironmental reconstruction at Zmajevac (Croatia) over the last three glacial/interglacial cycles

A high-resolution analysis of the Zmajevac loess-palaeosol sequence in East Croatia (Baranja) was performed with the purpose to get new insights into the palaeoenvironmental history during the last three glacial-interglacial cycles. The post-IR infrared stimulated luminescence signal of feldspar, stimulated at 290°C (thereafter pIRIR290) was used to establish a reliable chronological framework and revealed intensive sedimentation during (at least) the last 300 kyr, which was five times interrupted by climate optima resulting in the formation of soils (now palaeosols). The environmental magnetic measurements support the obtained luminescence chronology. Further chronological time control was reached by age modelling based on tie points from variations in frequency dependence of magnetic susceptibility and benthic δ18O variations from the LR04 stack of Lisiecki and Raymo (2005). The grain-size record provided information about the environmental conditions and dust accumulation. Additional palaeoenvironmental implications were provided by room temperature magnetic susceptibility and colourimetric analyses and revealed a continuously lower intensity of pedogenesis, coupled with constantly decreasing temperatures and precipitation from the oxygen isotope stage (OIS) 9 to the end of OIS 3. X-ray diffraction of the clay mineral fraction revealed chlorite, smectite and illitic material as dominant mineral phases. While clay minerals from loess are mostly detrital, smectite from palaeosols is partly of a pedogenic origin. The application of our multi-proxy approach, including relative and numerical dating techniques, provided new insights into a highly resolved terrestrial paleoenvironmental record of Eastern Croatia.

Dying in the Hallstatt Plateau: the case of wooden coffins from Iron Age necropolises in Mallorca (Balearic Islands, Western Mediterranean) and the difficulties in defining their chronology

Iron Age archaeology in Europe and the Mediterranean often faces significant difficulties to establish precise chronological frameworks by means of radiocarbon dating due to the so-called Hallstatt Plateau. This problem worsens in those archaeological sites excavated decades ago with a lack of stratigraphic control of the objects recovered. The archaeological studies carried out in Iron Age funerary contexts from Mallorca (Balearic Islands) are greatly affected by these two distorting factors. Therefore, it has been difficult to establish an accurate chronology for the origin and abandonment of certain individualization practices, such as the use of wooden coffins in collective necropolises. The goal of this paper is to overcome these limitations and to define the most reliable chronological framework for this funerary phenomenon by applying a multi-proxy approach. Thus, the chronological information provided by the detailed typological study of the material culture associated with the wooden coffins was connected to the results obtained from an extensive series of new radiocarbon dating of the wooden coffins. In addition, a wiggle-matching analysis (different 14C dates for the same wooden object corresponding to individual tree-rings) was also conducted in some wooden coffins in order to enhance the precision of the radiocarbon dates. Accordingly, the direct and indirect chronological information show that the use of wooden coffins in Mallorca started around 800–750 cal BC and was abandoned at c. 350–300 cal BC.

Dating Iberian prehistoric rock art: Methods, sampling, data, limits and interpretations

Rock art dating has been one of the major challenges since its discovery and recognition. The methods have evolved through the last century, beginning with the study of superpositions and style until to the application of numeric methods since the 1990s. The aim of this paper is to evaluate and publish an up-to-date database of all of the numerical dates currently available for Iberian prehistoric rock art sites. For this purpose, the manuscript reviews all the methods applied so far to Iberian rock art discussing the limits, the sampling involved, and the problems affecting the results. After that, we present and discuss the most relevant results related to each cultural graphic tradition (Palaeolithic, Levantine, Schematic and Megalithic rock art) assessing their value and limitations. Finally, we reflect on the future of rock art dating: unfortunately most of the motifs are not dateble in numeric terms, meaning we still have to combine traditional with numerical methods; but also, we need to keep working on the problems affecting these methods to be able to create a more reliable chronological framework of use to address other issues such as group mobility, cultural networks, and reutilisation of symbolic elements, to name a few.

Chronology of a Holocene Core From the Pearl River Delta in Southern China

Establishing a reliable chronological framework for sediments is crucial to the reconstruction of evolution process of estuarine delta, and the study of regional paleoenvironmental history, e.g. sea level fluctuations due to global climatic changes. High resolution chronology is still very limited for Holocene sediments in the Pearl River delta (PRD) in southern China. This study tries to construct a detailed chronology for core DA of 37.7 m in depth by using luminescence (seven samples) and radiocarbon (fourteen samples) dating techniques. Our results indicate that both luminescence and radiocarbon dating methods are suitable for the Holocene sediments in the PRD and that sediments of core DA were deposited during 7.3-0.18 ka. The 14C age is generally older than the OSL age for the sediment at the similar depths, and the age difference increased from 0.45 ka at the depth of 21 m to 0.98 ka at the depth of 35 m. The reason that 14C ages are relatively older might be caused by the carbon-reservoir effect which requires further study. The sedimentation rate increased from 3.74 m/ka during 7.3-2 ka to 7.92 m/ka in the last 2 ka. The appearances of rusty stains in upper unit of the core revealed that the water level was gradually falling. After the formation of underwater sand body at about 2 ka, the sediment was subject to continuous shifting between submergence and exposure.

Sedimentary history of the coastal plain of the south Yellow Sea since 5.1 Ma constrained by high-resolution magnetostratigraphy of onshore borehole core GZK01

The thick sedimentary sequences of the East Asian continental shelves are archives of information on tectonics, sea-level fluctuations, flood plain evolution, and changes in the East Asian monsoon climate. However, long sedimentary sequences with a reliable chronological framework from this setting are scarce. Here, we present an integration of lithostratigraphic, rock magnetic, and magnetostratigraphic results for the sedimentary sequence of a 285.0 m core (GZK01) recovered from the northern Jiangsu coastal plain of the onshore South Yellow Sea, eastern China. Alluvial, fluvial, lacustrine, and marine deposits were identified according to lithofacies analysis, and detrital magnetite and hematite are the main magnetic carriers. The magnetostratigraphic results show that core GZK01 records the Brunhes, Matuyama, Gauss, and Gilbert chrons, and has an extrapolated basal age of ∼5.1 Ma. This record is the oldest sedimentary sequence yet reported from the continental shelf of the South Yellow Sea. Integrating the geochronological framework with changes in lithofacies, a conceptual model of the environmental evolution of the northern Jiangsu coastal plain is proposed. For a long interval during the Pliocene, the drilling area was a lacustrine environment. From the Late Pliocene to the Early Pleistocene, the disappearance of the paleolake and a transition to a fluvial and marine environment suggests the peneplanation of the northern Jiangsu coastal plain. Cumulative land-sea interactions since 0.8 Ma subsequently shaped the modern geomorphology. The observed process of sedimentary evolution was possibly controlled by regional tectonics and long-term climate changes.

Chronostratigraphic framework of the East China Sea since MIS 6 from geomagnetic paleointensity and environmental magnetic records

Abstract Continental shelf is a globally important reservoir for terrigenous sediments, and provides sediment transportation pathways that extend from the shoreline to abyssal basins. Due to the strong land-sea interaction in response to frequent sea level change during the late Quaternary and methods' constraint, it is a big challenge to establish a reliable chronostratigraphy on the continental margin with terrigenous sediments dominance. Relative geomagnetic paleointensity (RPI) is quite useful for high-resolution chronostratigraphy in Brunhes epoch. In this study, relative paleointensity record for a sediment core (SFK-1, 82.9 m) from the outer East China Sea (ECS) shelf was studied. Rock magnetic results show that coarse vortex state magnetite is the dominant magnetic carrier throughout the core and that these sediments generally meet the accepted criteria for constructing relative paleointensity (RPI) record. RPI was established by normalizing the natural remanent magnetization (NRM) with isothermal remanent magnetization (IRM), both after 30 mT alternating demagnetization. Further, our RPI record was correlated with PISO-1500 and 7 age tie points were obtained. An age model is established for SFK-1 core with a basal age of 165 ka by combining the radiocarbon dates, relative geomagnetic paleointensity, and tandem correlation of environmental magnetic parameters to foraminiferal stable oxygen isotopes, which provides a reliable chronological framework for the later paleoenvironmental studies of ECS. The consistency of RPI record of SFK-1 and other worldwide observations suggest that global-scale pattern of geomagnetic paleointensity behavior is also documented in the sediments of the East China Sea, and the RPI of SFK-1 can be used as a reference curve for the RPI studies of other cores of ECS area, and even the whole west Pacific margin seas.

Constraining the transgression history in the Bohai Coast China since the Middle Pleistocene by luminescence dating

Three phases of transgression have been identified in the Middle to Late Pleistocene sedimentary succession in the Bohai Sea, northern China, which is considered to be key information for understanding environmental evolution and marine-terrestrial interaction in the East Asia. However, the timing of these transgressions still remains controversial. In this study, luminescence dating was performed on a core drilled in the North Bohai Coast to establish a reliable chronological framework of the transgression-regression cycles. After validating the applicability of luminescence dating for the Bohai sediments, quartz optically stimulated luminescence (OSL) and K-feldspar post-infrared (IR) IRSL (pIRIR) signals with elevated temperatures at 150, 225 and 290 °C were employed for dating the sediment core. The quartz OSL signal used for the upper 25 m of the sediment core was well-bleached, yielding finite ages within ca. 50 ka, whilst the K-feldspar pIRIR225 signal was also well-bleached for the Pleistocene samples with an extended dating limit to ca. 300 ka. The luminescence ages of ca. 200 ka and ca. 7.0–0.2 ka indicated that the lowermost and uppermost of three transgression units likely represent sea-level highstand during Marine Isotope Stages (MIS) 7 and 1, respectively, which were also evidenced by the consistency between the reconstructed palaeo-topography elevation and the contemporaneous global mean sea-level. Our luminescence ages of the second transgressive unit suggest it has a MIS 3 origin, being consistent with previous studies, but this appears to be unlikely as the level of the unit is significantly above the interstadial sea-level in the MIS 3. Further high-resolution luminescence dating of the second transgression is thus required.

Examining the chronology of transgressions since the late Pleistocene in the Fujian coast, southeastern China

The chronological framework of late Pleistocene and Holocene transgressional strata along the Fujian coasts in southeastern China were examined using new 14C dates, OSL ages, and diatom data from cores drilled in Longhai. This location was chosen because previous studies in the region have interpreted the occurrence of MIS3, MIS2, and Holocene transgressions. Our study, and a critical review of previous studies, show that 14C dates of bulk samples from coastal areas tend to be erroneously older than the depositional age due to enhanced input of old carbon via erosion of Mesozoic basement rocks from mountainous inlands. Also, OSL dates of deltaic and fluvial sediments either vary widely due to unsuitable luminescence properties of quartz grains or tend to be older than true depositional ages due to partial bleaching. As such, the previously considered late Pleistocene transgression may have occurred in the Holocene. Overall, the early Holocene transgression is well documented along Fujian coast revealing largely consistent early Holocene sea level histories from northern and southern sectors of Fujian coast. However, late Pleistocene transgressions are not well preserved along Fujian coasts, likely due to pervasive erosion. Our examination of the chronology of transgression in Fujian coast suggests cautions for 14C dating of bulk samples and for OSL dating of sediments in fluvial-deltaic settings, and emphasizes the importance of establishing a reliable chronological framework for understanding relative sea level history in this region and in similar settings elsewhere.

Comments on Higham and Heep (2017): ‘Reply to: “In the eye of the beholder: contextual issues for Bayesian modelling at the middle-to-upper Palaeolithic transition”, by Discamps, Gravina and Teyssandier (2015)’

ABSTRACTIn a response to our initial demonstration of the extreme sensitivity of Bayesian models for the Western European Middle-to-Upper Palaeolithic transition, Higham and Heep attempt to refute some of our arguments. They maintain that our modifications to their individual site models bear no meaningful impact and hence Higham et al.’s overall conclusion of a Mousterian-Châtelperronian coexistence in France remains valid. Such a scenario would considerably alter current perceptions of late Neanderthal cultural dynamics and potential interactions with modern human groups across Western Europe. Given the role of the Châtelperronian in on-going discussions concerning the final Neanderthals, establishing a reliable chronological framework for this techno-complex is fundamental. In addition to the high susceptibility of Bayesian models to even minor modifications, we maintain that secure, taphonomically tested contexts are the necessary prerequisite for model construction. We would like to take this opportunity to quickly address several of their context-specific criticisms and their general misinterpretation of the overall aim of our original critique.

Late Quaternary palaeoenvironmental reconstruction of sediment drift accumulation in the Malta Graben (central Mediterranean Sea)

The Malta Graben is a deep tectonic depression in the Sicily Channel, bounded by NW–SE normal faults and filled by thick Pliocene–Quaternary deposits. A previous analysis of a giant piston core (LC09) from the Malta Graben had revealed a wide range of sedimentary features (carbonate turbidites, bioturbated mud and scours), although the chronostratigraphic constraint of the stacking pattern has remained elusive. After establishing a reliable chronological framework based on seven radiocarbon dates for a shorter core from the Malta Graben (ANSIC03-735), a down-core analysis of planktonic foraminifer and coccolith abundance, stable isotopes and sediment grain size was carried out. Since the last glacial maximum, palaeoenvironmental conditions (surface fertility and deep chlorophyll maximum during the last glacial and the Younger Dryas; warm and oligotrophic water masses, with a deep nutricline and intense winter mixing during the Holocene) as well as selected calcareous plankton taxa trends and peaks seem to be similar to those reported for other central and western Mediterranean sites, possibly in spite of a unique response of these areas to late Quaternary climatic fluctuations. Four distinct layers, each tens of centimetres thick, are barren of foraminifers but not of coccoliths. Morphobathymetric data as well as new high-resolution and high-penetration seismic profiles show that prolonged contouritic activity has persisted on the western side of the Malta Graben. It is thus likely that layers barren of foraminifers are due to the overflow of fine-grained (clayey) material beyond drift channel dikes.

Magnetic stratigraphic dating of marine hydrogenetic ferromanganese crusts

Deep-sea hydrogenetic ferromanganese crusts are both potential polymetallic resources and records of long-term environmental changes. For palaeoceanographic studies, it is important to construct a detailed and reliable chronological framework. Here, we report the results of a detailed magnetostratigraphic and rock magnetic study of four hydrogenetic Fe-Mn crusts from the Pacific Ocean (PO-01), South China Sea (SCS-01, SCS-02) and Indian Ocean (IO-01). Two groups of characteristic remanent magnetization directions were defined with nearly antipodal normal and reversed polarities for samples PO-01, SCS-01 and SCS-02, indicating a primary record of the Earth’s magnetic field. The magnetostratigraphic framework, established via correlation with the Geomagnetic Polarity Time Scale 2012, implies growth rates of 4.82 mm/Ma, 4.95 mm/Ma, 4.48 mm/Ma and 11.28 mm/Ma for samples PO-01, SCS-01, SCS-02 and IO-01, respectively. Rock magnetic measurements revealed that the Fe-Mn crust samples from the Pacific Ocean and Indian Ocean were dominated by low coercivity, non-interacting, single-domain (SD) magnetite particles, whereas the South China Sea samples were dominated by SD/pseudo-single-domain (PSD) particles. Multidomain (MD) magnetite may also be present in all samples.