Organic facies variation in the late Kimmeridgian of the Boulonnais area (northernmost France)

Recent studies of the upper Kimmeridgian of the Boulonnais area (northernmost France) have provided a sequence-stratigraphical framework that is here used to help interpret variations in sedimentary organic matter (OM) content and composition in response to fluctuations in relative sea-level. The organic facies are characterised using a combination of palynofacies, bulk organic geochemistry (TOC, Rock Eval pyrolysis, and sulphur data), and the particle-size distribution of the total palynological residues. The organic facies show a good correlation with the sequence stratigraphy, exhibiting peak TOC, HI, total S and Sorg values in the lithofacies deposited around the two MFS. The palynofacies in these intervals is characterised by a high content of fluorescent, orange, marine AOM. There is a strong correlation between the orange AOM and the total and organic sulphur contents. Similar positive correlations between orange AOM and organic sulphur have previously been observed in the distal organic-rich sediments of the Kimmeridge Clay Formation of Dorset (lateral time equivalents of the Boulonnais facies), but there the sulphur contents are lower, indicating that organic sulphur content of orange AOM is not fixed, suggestive of preservation-related parallel but not intrinsically related trends. The S data can be used to estimate an apparent burial efficiency and hence the proportion of the primary productivity preserved; this allows a rough estimate of palaeoproductivity. Model calculations suggest that for a sulphide retention of 30–70% and uncompacted sedimentation rate estimates in the range 5–10 cm/ka, the mean palaeoproductivity was in the range 52–175 gC/m2/a (up to 6% of which was preserved). Thus, if the preservation is high, as is the case for MFS, the palaeoproductivity does not need to be above average for shelf waters to produce a given TOC

Determining the WIMP mass using the complementarity between direct and indirect searches and the ILC

We study the possibility of identifying dark matter properties from XENON-like 100 kg experiments and the GLAST satellite mission. We show that whereas direct detection experiments will probe efficiently light WIMPs, given a positive detection (at the 10% level for $m_{\chi} \lesssim 50$ GeV), GLAST will be able to confirm and even increase the precision in the case of a NFW profile, for a WIMP-nucleon cross-section $\sigma_{\chi-p} \lesssim 10^{-8}$ pb. We also predict the rate of production of a WIMP in the next generation of colliders (ILC), and compare their sensitivity to the WIMP mass with the XENON and GLAST projects.Comment: 32 pages, new figures and a more detailed statistical analysis. Final version to appear in JCA

Weak lensing, dark matter and dark energy

Weak gravitational lensing is rapidly becoming one of the principal probes of dark matter and dark energy in the universe. In this brief review we outline how weak lensing helps determine the structure of dark matter halos, measure the expansion rate of the universe, and distinguish between modified gravity and dark energy explanations for the acceleration of the universe. We also discuss requirements on the control of systematic errors so that the systematics do not appreciably degrade the power of weak lensing as a cosmological probe.Comment: Invited review article for the GRG special issue on gravitational lensing (P. Jetzer, Y. Mellier and V. Perlick Eds.). V3: subsection on three-point function and some references added. Matches the published versio