The Stardust spacecraft collected thousands of particles from comet 81P/Wild 2 and returned them to Earth for laboratory study. The preliminary examination of these samples shows that the nonvolatile portion of the comet is an unequilibrated assortment of materials that have both presolar and solar system origin. The comet contains an abundance of silicate grains that are much larger than predictions of interstellar grain models, and many of these are high-temperature minerals that appear to have formed in the inner regions of the solar nebula. Their presence in a comet proves that the formation of the solar system included mixing on the grandest scales.
The burial mound of Le Tumulus des Sables, southwest France, contains archaeological artefacts spanning from the Neolithic to the Iron Age. Human remains have been found throughout the burial mound, however their highly fragmented state complicates the association between the burial mound structure and the archaeological material. Radiocarbon dating and isotopic analyses of human teeth have been used to investigate the chronology, diet and mobility of the occupants. Radiocarbon dating shows that the site was used for burials from the Neolithic to Iron Age, consistent with the range of archaeological artefacts recovered. δ13C and δ15N values (from dentine collagen) suggest a predominately terrestrial diet for the population, unchanging through time. 87Sr/86Sr (on enamel and dentine) and δ18O (on enamel) values are consistent with occupation of the surrounding region, with one individual having a δ18O value consistent with a childhood spent elsewhere, in a colder climate region. These results showcase the complex reuse of this burial mound by a mostly local population over a period of about 2000 years.
Like elsewhere in Australia, the archaeology of northwest Queensland has focused on the antiquity of occupation and the continuity of that occupation through the Last Glacial Maximum (LGM), in an attempt to better understand the adaptive capabilities and strategies of early humans. Veth (1989, 1993) has hypothesised that the northwest Queensland savannah, as an important ‘corridor’ for the colonisation of Australia (e.g. Bird et al. 2005; Horton 1981), should contain ‘early’ sites; and furthermore that with the climatic deterioration associated with the LGM, such sites should fit one of two patterns: (1) they will be abandoned and display a cultural hiatus; or, (2) if located in resource-rich zones within catchments (‘local refuges’), they will continue to be utilised, though subsistence strategies will be modified to rely more heavily on locally available resources. The northwest Queensland sites of Colless Creek at Lawn Hill (Hiscock 1984, 1988), and GRE8 near Riversleigh (Slack 2007:218-251; Slack et al. 2004), both fit the second pattern, i.e. persistent occupation through the LGM with altered strategies to cope with increased aridity. However, outside these local refugia, sites pre-dating the LGM have not yet been located in the northwest Queensland savannah. For example, Mickey Springs 34 (Porcupine Gorge) provides evidence for human occupation from c.10,000 BP (Morwood 1990, 1992, 2002) and Cuckadoo Shelter in the Selwyn Ranges (Davidson et al. 1993) provides a near basal date of 15,270}210 BP; Veth (1989:87) argued that such sites reflect the post-LGM expansion of groups from refuges. The evidence available to date raises the question as to whether the wider northwest Queensland savannah corridor was indeed occupied in the pre-LGM period, when rainfall levels were higher and there was greater availability of surface water and food resources (cf. Hiscock and Wallis 2005).
Deep‐sea coral communities have long been recognized by fisherman as areas that support large populations of commercial fish. As a consequence, many deep‐sea coral communities are threatened by bottom trawling. Successful management and conservation of this widespread deep‐sea habitat requires knowledge of the age and growth rates of deep‐sea corals. These organisms also contain important archives of intermediate and deep‐water variability, and are thus of interest in the context of decadal to century‐scale climate dynamics. Here, we present Δ 14 C data that suggest that bamboo corals from the Gulf of Alaska are long‐lived (75–126 years) and that they acquire skeletal carbon from two distinct sources. Independent verification of our growth rate estimates and coral ages is obtained by counting seasonal Sr/Ca cycles and probable lunar cycle growth bands.
SUMMARY International Ocean Drilling Program (IODP) Expedition 341 recovered sediments from the south Alaska continental slope that preserves a well resolved and dated inclination record over most of the past ∼43 000 yr. The Site U1419 chronology is among the highest resolution in the world, constrained by 173 radiocarbon dates, providing the ability to study Palaeomagnetic Secular Variation (PSV) on centennial to millennial timescales. This record has an exceptionally expanded late Pleistocene sedimentary record with sedimentation rates commonly exceeding 100 cm kyr–1, while also preserving a lower resolution Holocene PSV record at the top. Natural and laboratory-induced magnetic remanences of U1419 u-channels from the 112-m-long spliced record were studied using stepwise AF demagnetization. Hysteresis loops were obtained on 95 and IRM acquisition curves on 9 discrete samples to facilitate magnetic domain state, coercivity and magnetic mineralogical determinations. Due to complexities related to lithology, magnetic mineralogy, and depositional and post-depositional processes, Site U1419 sediments are not suitable for palaeointensity studies and declination could not be robustly reconstructed. Progressive (titano-)magnetite dissolution with depth results in decreasing NRM intensity and signal-to-noise that is exacerbated at higher demagnetization steps. As a result, inclination measured after the 20 mT AF demagnetization step provides the most reliable directional record. Inclination appears to be well resolved with removal of just a few intervals influenced by depositional and/or sampling and coring deformation. The shipboard inclination stack from nearby IODP Site U1418, on a new age model developed from 19 radiocarbon dates on U1418 and 18 magnetic susceptibility-based tie-points to site survey core EW0408-87JC, verifies centennial to millennial scale variations in inclination observed in U1419. Comparisons with other independently dated records from the NE Pacific and western North America suggest that these sites likely capture regional geomagnetic variability. As such, this new high-resolution and well-dated inclination record, especially robust between 15 and 30 cal kyr BP, offers new geomagnetic insights and a regional correlation tool to explore this generally understudied part of the world.
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