This paper aims to define the first chrono-cultural framework on the domestication and early diffusion of the opium poppy using small-sized botanical remains from archaeological sites, opening the ...way to directly date minute short-lived botanical samples. We produced the initial set of radiocarbon dates directly from the opium poppy remains of eleven Neolithic sites (5900-3500 cal BCE) in the central and western Mediterranean, northwestern temperate Europe, and the western Alps. When possible, we also dated the macrobotanical remains originating from the same sediment sample. In total, 22 samples were taken into account, including 12 dates directly obtained from opium poppy remains. The radiocarbon chronology ranges from 5622 to 4050 cal BCE. The results show that opium poppy is present from at least the middle of the sixth millennium in the Mediterranean, where it possibly grew naturally and was cultivated by pioneer Neolithic communities. Its dispersal outside of its native area was early, being found west of the Rhine in 5300-5200 cal BCE. It was introduced to the western Alps around 5000-4800 cal BCE, becoming widespread from the second half of the fifth millennium. This research evidences different rhythms in the introduction of opium poppy in western Europe.
The Andean highlands challenged but did not prevent human exploration and occupation starting in the Late Pleistocene. The timing and nature of these events is an ongoing area of research and debate ...for which reliable chronologies are required. Our goal is to revise the chronological framework of the Telarmachay rockshelter, a key site from the Andean highlands. To achieve this objective, we have conducted a new AMS dating programme utilizing 33 camelid bone samples from 6 archaeological layers and used a Bayesian modelling approach to determine the chrono-stratigraphy. Our chronology spans a greater than 5000 year sequence dated between 9.0–8.0 and 3.7–3.1 kyr BP, permitting reassessment of the antiquity and duration of the Telarmachay occupation, facilitating comparison with other sites, and allowing examination of domestic and symbolic practices in relation to Holocene climatic variation in the Central Andes. This study highlights the importance of the Junín area in the Andean highland occupation sequence. It also underlines the need for new radiocarbon dates to reassess previous data and directly date artifacts.
•New chronology for Telarmachay, a key site in the history of human occupation in Andean highlands.•A 4000-year sequence of human occupation from Early Holocene to Late Holocene.•Importance of the Puna of Junín region in the sequence of Andean highlands occupation.•Datation of domestic and symbolic practices are revised according to the new sequence chronology and climatic variation.•Illustration of the need for direct radiocarbon dating of artifacts.
U/Th data obtained on CaCO3 layers covering rock art at Nerja Cave (Spain) evidence erroneous ages and an inverse relation between uranium concentration and apparent ages. This open system behavior ...could be due to a mechanism causing uranium mobility, resulting in apparent ages being too old with respect to their real age. This article also questions recently published U/Th data on samples from Ardales, Maltravieso and La Pasiega caves (Spain) where a few U/Th ages older than 40 ka BP, suggested that cave art could be attributed to Middle Palaeolithic population (Hoffmann et al., 2018). For these caves, U/Th data also display an inverse relation between U content and ages, indicating possible uranium mobility and erroneous ages.
•U/Th data were obtained on CaCO3 layers covering rock art at Nerja cave (Spain).•Inverse relation between U content and ages, suggest U mobility and wrong ages.•An inverse relation between U content and U/Th exists for previously published data.•The validity of old U/Th ages on spanish rock art published previously is questioned.
We generated high-resolution biochronological records in the Mediterranean Sea covering the period extending to the Late-glacial. The present study is based on micropaleontological, sea-surface ...temperature (SST) and oxygen isotopic analyses performed along three well-dated deep-sea cores: REC1353, KET80–19 and MD84–641 recovered in the Siculo-Tunisian Strait, Tyrrhenian Sea and Levantine Basin, respectively. The quantitative distributional patterns of planktic foraminifera permitted to identify seven biozones based on the apparition and/or disappearance of the main specific taxa or by their noticeable abundance peaks. Abundance records display that major changes in planktic foraminiferal assemblages have a similar pattern mainly in central and western basins. In particular, four recognized bio-events can be used to establish or to improve the chronology of Mediterranean deep-sea cores. The comparison of the SST estimates and foraminiferal records with those of NGRIP ice-core shows a similarity between the Greenland climate and the Mediterranean hydrology. This indicates that the main climate changes recorded in the North Atlantic are globally in phase with those observed in the Mediterranean region.
•We present a high-resolution biochronological records in the Mediterranean Sea.•Seven biozones are identified basing on the distributional patterns of planktic foraminifera.•Four bio-events were recognized, and they should improve the chronology of Mediterranean cores.•A similarity between the global climate and the Mediterranean hydrology is observed.
The distributions of dissolved and particulate thorium isotopes (230Th and 232Th) were established in samples from the BONUS GoodHope (BGH) IPY-GEOTRACES cruise in the SE Atlantic sector of the ...Southern Ocean (36°S-13°E to 57°S-0°, Feb.–Mar. 2008). The distribution of total (dissolved + particulate) 232Th is dominated by the inputs from continental margins. The non-linear profiles of dissolved 230Th are interpreted as due to the southward upwelling of the isopycnal surfaces. However, total 230Th and 232Th versus salinity plots illustrate departures from binary mixing and provides evidence for non-conservative behavior of both isotopes along the section. We propose a model for total 230Th and 232Th scavenging and mixing along isopycnal surfaces. We use this model to estimate particle settling speeds and isopycnal eddy diffusion coefficients along the BGH section. Data-model comparison suggests particle settling velocities in the range of 400–700 m/y and isopycnal eddy diffusivity of the order of 2000 m2/s.
•Small deviations of thorium isotopes from a conservative behavior occurs during isopycnal mixing through the ACC.•An advection-diffusion-scavenging model along neutral density surface is applied to thorium isotopes.•Combining thorium isotopes allows constraining particle settling speeds and isopycnal mixing coefficients.
εNd and normalized Rare Earth Elements (REE) patterns of benthic and planktonic foraminifera and Fe‐Mn coatings precipitated on sediments have been investigated for the South China Sea (SCS) to (1) ...assess the reliability of the extraction of past seawater εNd in the SCS and to (2) reconstruct past hydrological changes during the last 25 kyr. Reductively cleaned mono‐specific planktonic foraminifera (Globigerinoides ruber) and mixed benthic foraminifera in core‐top sediments from 1500 to 2400 m display similar εNd values to those of the modern Pacific Deep Water (PDW) (εNd of −3.9 to −4.4). Furthermore, the εNd of the reductive cleaning solutions shows similar εNd values to ones obtained on cleaned foraminifera. Combined with PAAS‐normalized REE patterns, these results confirm that the oxidative and reductive cleaning procedure applied to foraminifera does not totally remove all of the Fe‐Mn coatings and that εNd values yielded by cleaned planktonic foraminifera retain the εNd imprint of the bottom and/or pore water. εNd values obtained from a leaching procedure carried out on the bulk non‐decarbonated sediments are comparable to the εNd values of the modern PDW, whereas a similar leaching procedure applied to decarbonated sediments reveals a bias due to contamination with Nd deriving from lithogenic particles. In core MD05‐2904, seawater εNd, reconstructed from planktonic foraminifera, indicates that the last glacial period is characterized by lower εNd (−5.2 ± 0.2 to −6.4 ± 0.3) than the late Holocene (−4.1 ± 0.2). Assuming that Nd input from river does not change strongly the εNd of the PDW of the northern SCS, these εNd variations suggest a higher relative proportions of southern‐sourced water in the deep water of the western subtropical Pacific Ocean during the last glacial period.
Key Points:
εNd of foraminifera investigated for the first time in the South China Sea
Improvement of the extraction of seawater Nd isotopes from marine sediments
Past hydrological changes in the subtropical Pacific for the last 25 kyr
Boron isotopes in marine carbonates are increasingly used to reconstruct seawater pH and atmospheric pCO2 through Earth’s history. While isotope ratio measurements from individual laboratories are ...often of high quality, it is important that records generated in different laboratories can equally be compared. Within this Boron Isotope Intercomparison Project (BIIP), we characterised the boron isotopic composition (commonly expressed in δ11B) of two marine carbonates: Geological Survey of Japan carbonate reference materials JCp‐1 (coral Porites) and JCt‐1 (giant clam Tridacna gigas). Our study has three foci: (a) to assess the extent to which oxidative pre‐treatment, aimed at removing organic material from carbonate, can influence the resulting δ11B; (b) to determine to what degree the chosen analytical approach may affect the resultant δ11B; and (c) to provide well‐constrained consensus δ11B values for JCp‐1 and JCt‐1. The resultant robust mean and associated robust standard deviation (s*) for un‐oxidised JCp‐1 is 24.36 ± 0.45‰ (2s*), compared with 24.25 ± 0.22‰ (2s*) for the same oxidised material. For un‐oxidised JCt‐1, respective compositions are 16.39 ± 0.60‰ (2s*; un‐oxidised) and 16.24 ± 0.38‰ (2s*; oxidised). The consistency between laboratories is generally better if carbonate powders were oxidatively cleaned prior to purification and measurement.
Key Points
The boron isotopic composition (δ11B) of two biogenic carbonate reference materials was measured in ten laboratories.
Unprecedentedly good interlaboratory consistency for both carbonate materials.
Gentle oxidative pre‐treatment of biogenic carbonates led to better overall consistency between laboratories.
The comparison between different climate model simulations of water hosing experiments under glacial conditions points toward diverging responses in Sea Surface Temperature changes (SST) especially ...in the Southeast Pacific (SEP). This suggests that reconstituting the latitudinal SST gradient in the SEP is a critical parameter for a better understanding of the mechanisms behind the abrupt climatic events since the last glacial period. Here we present, high-resolution records of SST, using planktonic foraminiferal assemblages and alkenone temperature reconstructions and stable oxygen and carbon isotopes from three deep-sea sediment cores along a latitudinal transect off the southern Chilean coast. This allowed us to reconstruct the variations of the latitudinal SST gradient and the Subtropical Front movements in the SEP. The SST results suggest a clear Antarctic timing consistent with the bipolar seesaw control, especially during the late glacial and the deglaciation. Our records do not suggest a complete oceanic heat transfer signal, highlighting the implication of an atmospheric component in the heat transfers between the two hemispheres, controlled by the latitudinal movements of the intertropical convergence zone in the Atlantic and the associated weaker South Pacific westerly split jet. Furthermore, our records indicate variable conditions during the Holocene, and also emphasize the influence of local fresh water inputs from the Patagonian ice sheet and/or precipitation on the SST fresh water input estimates along the Chilean margin (North and South of 49° S) from the onset of the deglaciation until 8 kyr cal. BP.
•Sea surface temperature reconstruction since the last 22 kyr (Southeast Pacific).•Temperature were reconstructed using planktonic foraminifera assemblage counts and alkenones data.•Melting of Patagonian Ice-Sheets influenced coastal temperatures.•Latitudinal temperature gradient shows the migrations of the subtropical front.•The movements of the subtropical front respond to the bipolar seesaw.
Climatic and oceanographic changes, as occurring at a glacial–interglacial scale, may alter the environmental conditions needed for the development of prolific cold-water coral reefs and mounds. ...Studies constraining the temporal distribution of cold-water corals in the NE Atlantic suggested the cyclic changes of the Atlantic Meridional Overturning Circulation as the main driver for the development and dispersal of cold-water coral ecosystems. However, conclusions were hindered by lack of data from the NW Atlantic. Aiming to overcome this lack of data, the temporal occurrence of cold-water corals in the Cape Lookout area along the southeastern US margin was explored by U-series dating. Furthermore, the local influence of the regional water masses, namely the Gulf Stream, on cold-water coral proliferation and occurrence since the Last Glacial Maximum was examined. Results suggest that the occurrence of cold-water corals in the Cape Lookout area is restricted to interglacial periods, with corals being present during the last ~7kyr and also during the Eemian (~125ka). The reconstructed local environmental conditions suggest an offshore displacement of the Gulf Stream and increased influence from the Mid-Atlantic Bight shelf waters during the last glacial period. During the deglacial sea level rise, the Gulf Stream moved coastward providing present-day-like conditions to the surface waters. Nevertheless, present-day conditions at the ocean sea floor were not established before 7.5calka BP once the ultimate demise of the Laurentide ice-sheet caused the final sea level rise and the displacement of the Gulf Stream to its present location. Occasional presence of the Gulf Stream over the site during the Mid- to Late Holocene coincides with enhanced bottom current strength and a slightly higher bottom water temperature, which are environmental conditions that are favorable for cold-water coral growth.
•Cold-water corals in the Cape Lookout area (NW Atlantic) occur during interglacials.•Coral colonization is related to environmental changes driven by the Gulf Stream.•Holocene occurrence is related to enhanced currents and temperatures above 6°C.
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